Facultad de Ingeniería / Artículos Publicados

Artículos publicados por académicos de la Facultad de Ingeniería en revistas arbitradas e indexadas.

Fuente: Scopus.

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Artículos 2018

Characterization of superficial modification of ferrous rusted substrates subjected to dechlorination-electrochemical process
Journal of Adhesion Science and Technology
https://doi.org/10.1016/j.segan.2022.100658
Jesús Rafael González Parra¹ , Alba Covelo Villar¹ , R. J. Ramírez ¹ , A. Tejeda ² , A. Ortega ³ , Miguel Ángel Hernández Gallegos¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
³ Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares

Keywords: Carbon steel, SEM, X-ray diffraction, rust, dechlorination
Abstract: Preservation of archaeological artefacts after their removal from saline media is a difficult task due to the chloride content of the oxide layers which are unstable in atmospheric conditions, especially if the relative humidity exceeds 85%. For this reason, removal of chlorides from rust layers is one of the priorities of conservationists or restorers of historical artefacts. However, removal of chloride ions is not an easy procedure because of the many considerations involved in the process. In this research, artificially pre-rusted iron samples and an actual historical cannonball were subject to a dechlorination process in a potassium hydroxide solution to measure constant chloride release in a bulk solution. After the chloride removal process, a commercial protective layer was applied to the rust for stabilization purposes. It was calculated that the kinetics of the dechlorination process is driven by diffusion behaviour following Fick’s second law. When this diffusion process prevails, the dechlorination extraction affects the integrity of rust layers as is demonstrated with scanning electron microscopy and X-ray diffraction analyses. It was proven that the chloride removal procedure causes the studied iron layers to stiffen, provoking superficial modification and, in some cases, fractures of the rust. By means of electrochemical impedance spectroscopy it was calculated that the magnitude of the positive effect of the dechlorinated samples depends on the protective features of the rust. Therefore, this research reveals that an efficient chloride removal procedure depends on the electrochemical properties of the dechlorination process and the initial morphology of the iron rust.

Initial verification of AZNHEX hexagonal-z neutron diffusion code with MCNP6 for two different study cases
Progress in Nuclear Energy
https://doi.org/10.1016/j.pnucene.2018.03.017
Juan Galicia Aragón¹ , Juan Luis François Lacouture¹ , Guillermo Elías Bastida Ortiz¹ , Cecilia Martín del Campo¹ , Julio Amhed Vallejo Quintero¹ , Edmundo Del Valle Gallegos²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Instituto Politécnico Nacional, Escuel Superior de Física y Matemáticas

Keywords: Neutron diffusion code, Reactor analysis, Hexagonal-z geometry, Finite element method
Abstract: The core of the AZTLAN Mexican reactor analysis platform consists of a thermo-hydraulic code (AZTHECA), a neutron transport code (AZTRAN) and two neutron diffusion codes, namely AZKIND and AZNHEX. These codes are currently in the testing phase by simulating a variety of fuel assemblies and nuclear reactor cores to compare and verify their results with those obtained by codes globally used in the nuclear community such as SERPENT, CASMO/SIMULATE, MCNP and others. The main objective of this task is to improve future versions of the AZTLAN platform codes to obtain reliable results for the user. To verify the current version of AZNHEX neutron diffusion code, two cases were considered. The simulation of a WWER-440 fuel assembly was the first case analyzed, and the second case was the core of a sodium-cooled fast reactor in steady state, with control rods fully withdrawn. The comparison and verification of the results (neutron multiplication factor, axial and radial power distributions and radial neutron flux distribution) for both cases were done employing MCNP6 Monte Carlo code. Certain deviations were found between AZNHEX and MCNP6, since AZNHEX is a diffusion code and it is being compared against a Monte Carlo code. However, it is shown that the results provided to the user are reliable since they exhibit a good degree of fidelity.

Recycling of Amazonian detrital zircons in Mixteco terrane, Southern Mexico: Paleogeographic implications during Jurassic - early Cretaceous and Paleogene times
Journal of South American Earth Sciences
https://doi.org/10.1016/j.jsames.2018.02.011
Gilberto Silva Romo¹ , Claudia Cristina Mendoza Rosales¹ , Emiliano Campos Madrigal¹ , Axél Morales Yáñez¹ , Alam Israel De la Torre González¹ , Juan Iván Nápoles Valenzuela¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Cosoltepec block, Ayú complex, Sedimentary facies, Alluvial fan
Abstract: In the northeastern Mixteco terrane of southern Mexico, in the Ixcaquixtla-Atzumba region, the recycling of Amazonian detrital zircons records the paleogeography during the Mesozoic period in the context of the breakup of Pangea, a phenomenon that disarticulated the Sanozama-La Mora paleo-river. The clastic units of southern Mexico in the Ayuquila, Otlaltepec and Zapotitlán Mesozoic basins, as well as in the Atzumba Cenozoic basin, are characterized by detrital zircon contents with ages specific to the Amazonian craton, ranging between 3040 and 1278 Ma. The presence of zircons of Amazonian affinity suggests a provenance by recycling from carrier units such as the La Mora Formation or the Ayú Complex. In the area, the Ayú and Acatlán complexes form the Cosoltepec block, a paleogeographic element that during Early Cretaceous time acted as the divide between the slopes of the paleo-Gulf of Mexico and the paleo-Pacific Ocean. The sedimentological characteristics of the Jurassic-Cenozoic clastic successions in the Ixcaquixtla-Atzumba region denote relatively short transport in braided fluvial systems and alluvial fans. In this way, several basins are recognized around the Cosoltepec block. At the southeastern edge of the Cosoltepec block, the Ayuquila and Tecomazúchil formations accumulated in the Ayuquila continental basin on the paleo-Pacific Ocean slope. On the other hand, within the paleo-Gulf of Mexico slope, in the Otlaltepec continental basin, the Piedra Hueca and the Otlaltepec formations accumulated. The upper member of the Santa Lucía Formation accumulated in a transitional environment on the southwestern shoulder of the Zapotitlán basin, as well as on the paleo-Gulf of Mexico slope. In the Ayuquila basin, a marine transgression is recognized that advanced from south to north during the Late Jurassic. At the northeastern edge of the Cosoltepec block, we propose that the Santa Lucía formation attests to a transgression from the paleo-Gulf of Mexico during the Early Cretaceous. Thus, the Cosoltepec block flood occurred during the Albian-Cenomanian, as recognized by the Cipiapa Limestone accumulation. The subsequent uplift of the region and its incorporation into the continental slope is attested by the Atzumba Formation, which offers further evidence of the content of Amazonian detrital zircons recycled from the Ayú Complex. The Atzumba Formation accumulated as alluvial fans during the Paleogene at the hanging wall of the Chazumba fault, which displaced the Cosoltepec block. That is, the detrital zircons in the clastic successions of the Ixcaquixtla-Atzumba region bear indirect testimony to the origin and Amazonian affinity of the Ayú Complex and/or other lithodemes of the Acatlán Complex.

A new method of simulating volcanic eruption column formation and dispersion of ejected ash clouds
Meteorological Applications
https://doi.org/10.1002/met.1679
F. Espinosa Arenal¹ , Rubén Ávila Rodríguez² , S.S. Raza ³
¹ Universidad Veracruzana, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Pakistan Institute of Engineering and Applied Sciences, Faculty of Engineering

Keywords: eruption column modelling, volcanic ash, turbulent dispersion, atmospheric modelling
Abstract: A new Eulerian-Lagrangian model is developed to predict the formation of eruption columns, and the long range transport and dispersion of volcanic ash clouds in the atmosphere. The model capability is tested by presenting the atmospheric dispersion of ash clouds released during two eruptions of the Popocatepetl volcano in Mexico. The atmospheric wind predictions were made by using the Eulerian regional atmospheric modelling system (RAMS), which is well tested over the Mexico region. Two Lagrangian models were also employed: (1) an eruption column formation model and (2) a Lagrangian stochastic deterministic (LSD) particle dispersion model. In a LSD model, the continuous plume is simulated by several puffs (clouds) successively released in the atmosphere. (1) The influence of the wind on the eruption column, (2) the transport and dispersion of the ash cloud and (3) the concentration of volcanic ash using a smoothed particle hydrodynamics technique are reported. This is thought to be a unique combination of mathematical prediction models and would be of interest to the broader scientific community. The formation of the eruption column is compared with ground observations, while the long range trajectory of the ash clouds is compared with images based on satellite data, qualitatively. In both cases the agreement within the observed and simulated plume shape was found to be satisfactory which indicated the suitability of the Eulerian wind prediction model (RAMS) in the region as well as that of Lagrangian models employed in the study.

An alternative algorithm for the linearization process of transmutation and decay networks
Computer Physics Communications
https://doi.org/10.1016/j.cpc.2018.04.024
Carlos Antonio Cruz López¹ , Juan Luis François Lacouture¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bateman equation, Linear method, Burnup, Linearization, Depth- First-Search, Transmutation and decay networks
Abstract: To modeling the changes occurring in the nuclear reactor’s fuel composition, it is necessary to solve a coupled system of first order differential equations, known as the Bateman equations. Nowadays, there are two main methods to accomplish this task: the linear chain method and the matrix exponential method. The general procedure for the linear chain method consists in breaking a transmutation network into independent depletion chains (also known as "linear chains”) and then solving each one analytically. The common way to build these linear chains is using a Depth-First-Search (DFS) algorithm, which consists in finding every possible path in a network, tracking the decay and transmutation reactions for a set of isotopes until one stable appears or there is no more information to continue. At this point, the algorithm moves backwards searching a branch or an untraveled path, and then the procedure is repeated. In the present work, an alternative new algorithm for building linear chains is developed, which uses a special notation and reduces the problem of finding paths to the problem of ordering a sequence of characters. Unlike the DFS, the algorithm developed has not a backward routine, but it has a "fill” procedure instead. The last property decreases the computation time spent in build linear chains and is useful with cyclic chains. We carry out a comparative analysis including computational schemes based on the running time of the algorithms, versus the length of the linear chains built. We considered two kinds of networks: (1) where the initial element is a heavy isotope that undergoes fission reaction and (2) where the first element is a fission product. In all the practical scenarios the proposed algorithm is faster than the DFS’s, nevertheless when the values of the chain’s length are large enough, the running times converge, being necessary to use a more complex and advanced sorting method.

Middle Jurassic ankylosaur tracks from Mexico
Boletín de la Sociedad Geológica Mexicana
http://dx.doi.org/10.18268/BSGM2018v70n2a8
Rubén A. Rodríguez De la Rosa¹ , María Patricia Velasco De León² , Javier Arellano Gil³ , Diego Enrique Lozano Carmona²
¹ Universidad Autónoma de Zacatecas, Unidad Académica de Ciencias de la Tierra
² Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Zaragoza
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Ankylosauria, Tetra podosaurus, Ichnology, Middle Jurassic, Oaxaca, Mexico
Abstract: A track-bearing locality in one of the shores of the Ñumí River, near the City of Tlaxiaco, northwestern Oaxaca, southern Mexico, preserves the footprints of sauropod and theropod dinosaurs; it is located within the stratigraphic sequence of the Zorrillo-Taberna Indiferenciadas Formation, of Middle Jurassic (Bajocian) age. A well-preserved manus-pes set of ankylosaurian affinity (Tetrapodosaurus) is preserved on a rock block from this formation. These tracks are preserved as convex hyporeliefs. The pes impression is tetradactyl, with ventrally curved toe tips, suggesting that these were deeply impressed in the sediment. Manus impression is pentadactyl, with short and blunt digits. A curved structure preserved together with these footprints is herein interpreted to be a tail drag. The stratigraphic unit from whence this block came was identified and two additional ankylosaurian tracks, were found preserved in situ as natural sandstone casts. An isolated handprint, has the same features that fit the ankylosaurian hand morphology; however, some features such as a medio-lateral concavity are indicative of the presence of a well-developed palmar pad, and could suggest the functional mechanics of the ankylosaurian manus. The Zorrillo-Taberna Indiferenciadas Formation is a coal-bearing formation; after the global record, ankylosaur footprints are concentrated in coal-bearing and floodplain facies, thus suggesting, that at least the North American Ankylosauria were adapted to similar paleoecological conditions from Middle Jurassic to Early Cretaceous times. It represents the second report of ankylosaurian tracks from Mexico and the southernmost record of the ichnogenus Tetrapodosaurus in North America. In this way, it suggests a geographic continuum in the record of the Ankylosauria to southern North America during Middle Jurassic times. With their Middle Jurassic age, these footprints represent the oldest ankylosaurian ichnofossils known to date.

Pulsatile electroosmotic flow in a microchannel with asymmetric wall zeta potentials and its effect on mass transport enhancement and mixing
Chemical Engineering Science
https://doi.org/10.1016/j.ces.2018.03.051
I. Medina ¹ , M. Toledo ¹ , Federico Méndez Lavielle² , Oscar Eladio Bautista Godínez¹
¹ Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Mass transport, Pulsatile electroosmotic flow, Asymmetric zeta potentials, Mixing and separation
Abstract: In this work, we analyze theoretically the mass transport of a neutral solute in a pulsatile electroosmotic flow (PEOF), circulating in a parallel flat plate microchannel whose walls are characterized by asymmetric zeta potentials. The microchannel is connected to a two reservoirs having different concentrations. To analyze the mass transport in the PEOF, the Debye-Hückel approximation is assumed, and the electric potential in the Debye length is obtained from the Poisson-Boltzmann equation. Then, using the momentum and concentration equations, the flow and concentration fields are analytically determined for the periodic stage. Such field distributions depend principally on three dimensionless parameters: an angular Reynolds number, the Schmidt number, and the ratio between the half height of the channel and the Debye length. For obtaining insight on the physical aspects of the studied phenomenon, an asymptotic solution is additionally obtained in the limits of small and large values of the angular Reynolds number. Some important results derived from this analysis show the conditions for which the mass transport of a neutral solute can be enhanced and the circumstances whereby mixing of species is achieved.

Towards a Formalization of a Framework to express and Reason About Software Engineering Methods
Computing and Informatics
https://doi.org/10.4149/cai_2018_1_109
Miguel Ehécatl Morales Trujillo¹ , Hanna Jadwiga Oktaba² , Francisco Hernández Quiroz² , Boris Escalante Ramírez¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Facultad de Ciencias

Keywords: Software engineering, situational method engineering, ontology, description logics, ESSENCE, KUALI-BEH
Abstract: Software Engineering is considered a knowledge-intensive discipline, in which knowledge creation, collection and sharing is an uninterrupted process. However, a large part of this knowledge exists in a tacit form and depends on practitioners. Therefore defining a mechanism to transform tacit knowledge into explicit one is of upmost importance. This paper presents a formalization approach to represent Software Engineering practitioners' tacit knowledge, which is related to their ways of working, as a set of explicit statements. The formalization is based on KUALI-BEH, which is a normative kernel extension of ESSENCE formal specification, and consists of three parts: an ontology to share a common representation of knowledge as a set of concepts; a Situational Method Engineering based algebra that represents well-defined method properties and operations; and a knowledge representation of the ontology and algebra using Description Logics. The main objectives of this initial formalization are to improve communication among humans and machines, computational inference and reuse of knowledge.

Ultrafine gradient microstructure induced by severe plastic deformation under sliding contact conditions in copper
Materials Characterization
https://doi.org/10.1016/j.matchar.2018.02.017
Carlos Gabriel Figueroa ¹ , Rafael Schouwenaars Franssens² , Jacinto Cortés Pérez¹ , Roumen Petrov ³ , Leo Kestens ³
¹ Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Aragón
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Ghent University, EEMMeCS Department

Keywords: Sliding contact, Copper, Severe plastic deformation, Grain refinement, Recrystallisation, Nanohardness
Abstract: Sliding contact induces severe plastic deformation (SPD) at the surface of ductile materials and induces a microstructural gradient associated to a significant increase of hardness toward the surface. This gradient allows observing all stages of grain refinement in SPD, as illustrated here by the analysis of polycrystalline electrolytic copper tested in a coaxial tribometer. Materials tested in the cold-rolled state and after annealing were characterised by high-resolution electron backscattering diffraction and nano-indentation. The incremental plastic strain produces an ultrafine microstructure in the top layers, which gradually changes to the original size in unaffected material. In cold-rolled material, an intermediate recrystallised layer is observed. The separation of the Misorientation Angle Distribution (MAD) in a low-angle portion and a high angle portion allows characterising the accumulation of strain induced misorientation, while the Kernel Average Misorientation (KAM) provides information on the evolution of substructure at the finest levels. The results point toward a process where strain-induced effects compete continuously with recrystallisation, except for the surface layer in the cold-rolled material, where dynamic recrystallisation is dominant. Combining the information from KAM and subgrain size distribution, the measured hardness can be explained as a combination of grain size and dislocation hardening.

Adaptive dynamical tracking control under uncertainty of shunt DC motors
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2018.07.033
Francisco Beltrán Carbajal¹ , Rubén Tapia Olvera² , Irvin López García¹ , Daniel Guillen ³
¹ Universidad Autónoma Metropolitana, Unidad Azcapotzalco
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias

Keywords: DC motor, Velocity control, Neural networks, Variable torque, Uncertainty
Abstract: A new adaptive velocity trajectory tracking control scheme for nonlinear shunt DC electric motors subjected to unmeasurable variable load torque and parametric uncertainty is proposed. Artificial neural networks and dynamical tracking error compensators are synergically combined to avoid dependence on detailed mathematical models of uncertain nonlinear systems and significantly improve the controller robustness and efficiency. The introduced robust tracking control approach can efficiently adapt to diverse uncertain operating scenarios. A priori knowledge or real-time estimation of disturbances and system parameters are unnecessary. The proposed output feedback dynamical tracking control can be extended to a wide class of controllable electric power systems operating under uncertainty. Analytical and numerical results prove the robust and efficient performance of the dynamical tracking control.

Dissipative approach to sliding mode observers design for uncertain mechanical systems
Automatica
https://doi.org/10.1016/j.automatica.2017.10.016
W. Alejandro Apaza Pérez¹ , Jaime Alberto Moreno Pérez² , Leonid Fridman Golredich¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Sliding-mode observers, Velocity observers, Nonlinear observers, Dissipative observers
Abstract: A class of nonlinear uncertain mechanical systems with the Coriolis term, is considered. Since these systems generally do not satisfy the bounded-input-bounded-state property, a global sliding-mode observer with theoretically exact finite-time convergence using dissipative properties, is proposed.

Electrochemical characterization of PVA/SA nanofibers obtained by electrospinning processing
Surface and Interface Analysis
https://doi.org/10.1002/sia.6412
Alba Covelo Villar¹ , Karla Gómez ¹ , María del Pilar Corona Lira¹ , Alejandro Cuauhtémoc Ramírez Reivich¹ , Miguel Ángel Hernández Gallegos¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: biomaterials, cross-linking, EIS, nanofiber, sodium alginate
Abstract: Sodium alginate (SA), a linear polysaccharide which is present in different forms, is commonly used for tissue engineering. One of the main challenges of using SA in tissue engineering consists of the fabrication of nanoparticles/nanofibres for cell culture scaffolds. Because SA has been developed for medical purposes, it is necessary to measure, among others, the electrochemical properties because they provide information of biological activity related to metabolic behaviour. This work focuses on the measurement, interpretation, and characterization of electrochemical properties by means of electrochemical impedance spectroscopy of SA electrospun fibres mixed with poly(vinyl alcohol) (PVA) at different PVA/SA concentration ratios (3.5, 4, and 5 wt.%). To stabilize the PVA/SA systems, a calcium chloride solution was used for the cross-linking process. The electrochemical impedance spectroscopy results show that PVA/SA nanofibres immersed in calcium chloride react instantly and the dielectric properties of the PVA/SA system change until the cross-linking process is stabilized in time. The overall cross-linking time depends on the PVA/SA ratio which means, the more SA concentration mixed in PVA solution, the shorter the cross-linking time needed for a stabilization plateau. The 5 wt.%, PVA/SA gives not only the highest impedance values after cross-linking treatment, but also the more constant and reproducible electrochemical features in time, in conjunction with a more homogeneous, compact and low porous nanofibre.

Influencia del aporte sedimentario del río Cozoaltepec en la anidación de tortugas en la playa La Escobilla, Oaxaca, en el Pacífico mexicano
Hidrobiologica
https://hidrobiologica.izt.uam.mx/index.php/revHidro/article/view/1108
Mayumi Amparo Cabrera Ramírez¹ , Arturo Carranza Edwards² , Enrique Quintero De Leonardo²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología

Keywords: análisis textural, arribazón, perfil de playa, playa La Escobilla, tortuga golfina
Abstract: Antecedentes. La Escobilla es una playa arenosa que constituye el principal sitio de anidación de la tortuga golfina (Lepidochelys olivacea) en la costa mexicana. Los estudios relacionados con el hábitat de estos organismos permiten establecer estrategias de conservación dentro de las cuales es necesario conocer los parámetros físicos que afectan las arribazones. Objetivos. Este estudio determinó las características texturales de los sedimentos litorales y la morfología de la playa con el fin de evaluar sus posibles relaciones con las anidaciones de esta especie. Métodos. Se colectaron muestras de sedimento en las zonas de infraplaya, mesoplaya y supraplaya a lo largo de 15 km de playa; se realizaron levantamientos topográficos de perfiles de playa, y se obtuvieron los parámetros texturales de Mzf (tamaño gráfico promedio) y sf (clasificación gráfica inclusiva). Resultados. Las zonas de mesoplaya y de supraplaya con pendiente suave del orden de 2° a 4°, tamaño de grano de arenas medias (1f a 2f) y la apertura de la barra arenosa por la desembocadura del río Cozoaltepec en época de lluvias parecen favorecer las anidaciones. Conclusiones. Las zonas con mayores sitios de anidación se encuentran a una distancia de 2.3 km hacia el este del río Cozoaltepec, donde aparentemente la morfología de la playa es más adecuada, ya que su pendiente no es demasiado alta y la playa es suficientemente amplia para las anidaciones. Además, en esa localidad se presentó el mayor número de arribazones de las tortugas.

Modeling and analysis of LTE connectivity in a high mobility vehicular environment
Computers and Electrical Engineering
https://doi.org/10.1016/j.compeleceng.2018.04.007
Andres Burbano Abril¹ , Robert Edwards ² , Víctor Rangel Licea¹ , Raúl Aquino Santos³ , Miguel López Guerrero⁴ , Roy Kalawsky ² , Mohammadreza Behjati ²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Loughborough University, 5G Research Centre
³ Universidad de Colima, Escuela e Telemática
⁴ Universidad Autónoma Metropolitana, Unidad Iztapalapa

Keywords: Benchmarking, Channel Quality Indicator, Finite-state Markov chain, LTE, Vehicular environment
Abstract: Long-Term Evolution (LTE) technology has several features that make it an attractive alternative to be used in vehicle-to-infrastructure communications for intelligent transportation systems. However, before LTE can be widely used in this context, a number of analyses must provide convincing evidence that critical network functions (e.g. resource allocation strategies) yield adequate performance. To this end, in this work, we introduce a Markov-chain based model for LTE downlink channel quality, a prime factor affecting performance. Our model comes from the analysis of a large number of measurements of LTE Cell-Specific Reference Signals that were collected through a crowdsourcing application on a motorway in the UK. The model is intended to be used in performance evaluation studies and we exemplify its use with a case study, where we estimate the downlink transmission capacity of an LTE network. We also discuss other potential applications.

Nonlinear frequency response based adaptive vibration controller design for a class of nonlinear systems
Mechanical Systems and Signal Processing
https://doi.org/10.1016/j.ymssp.2017.03.017
Suresh Thenozhi ¹ , Yu Tang Xu²
¹ Universidad Autónoma de Querétaro,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Adaptive control, Convergence analysis, Cubic damping, Frequency response function, Satellites, Vibration control
Abstract: Frequency response functions (FRF) are often used in the vibration controller design problems of mechanical systems. Unlike linear systems, the FRF derivation for nonlinear systems is not trivial due to their complex behaviors. To address this issue, the convergence property of nonlinear systems can be studied using convergence analysis. For a class of time-invariant nonlinear systems termed as convergent systems, the nonlinear FRF can be obtained. The present paper proposes a nonlinear FRF based adaptive vibration controller design for a mechanical system with cubic damping nonlinearity and a satellite system. Here the controller gains are tuned such that a desired closed-loop frequency response for a band of harmonic excitations is achieved. Unlike the system with cubic damping, the satellite system is not convergent, therefore an additional controller is utilized to achieve the convergence property. Finally, numerical examples are provided to illustrate the effectiveness of the proposed controller.

Barrier function-based adaptive sliding mode control
Automatica
https://doi.org/10.1016/j.automatica.2018.03.078
Hussein Obeid ¹ , Leonid Fridman Golredich² , Salah Laghrouche ¹ , Mohamed Harmouche ³
¹ Universite Bourgogne Franche-Comté/UTBM,,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Université Paris Saclay, Laboratoire des signaux et systemes

Keywords: Sliding mode, Adaptive control, Barrier functions
Abstract: In this paper, a new barrier function-based adaptive strategy is proposed for first order sliding mode controller. This strategy is applied to a class of first order disturbed systems whose disturbance is bounded with unknown boundary. The proposed barrier strategy can ensure the convergence of the output variable and maintain it in a predefined neighborhood of zero independent of the upper bound of the disturbance, without overestimating the control gain.

Cox modified model to describe the time evolution of a drop deformation for high viscosity drops in simple shear flow
International Journal of Multiphase Flow
https://doi.org/10.1016/j.ijmultiphaseflow.2018.02.003
Carlos Escalante Velázquez¹ , Israel Yescas Rosas² , Marco Reyes ³ , Enrique Geffroy ²
¹ Centro de Ingeniería y Desarrollo Industrial,
² Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Transient drop deformation, Simple shear flow, High viscous drops
Abstract: In this work a modification of Cox's model for the deformation of a highly viscous drop is presented, which describes accurately the period of the oscillations during transient deformations. It is demonstrated that the oscillation period depends not only on the shear rate as predicted by Cox model but also on the viscosity ratio. This modified model is obtained from the analysis of numerical simulations of drop deformation using the boundary element method, while the experimental results are those obtained in quasi-simple shear flow generated in a two roll mill (2TRMs) device, as well as experimental data available in the literature. The predictions of the periods match very well with experimental data.

Design and prototyping medium-frequency transformers featuring a nanocrystalline core for DC-DC converters
Energies
https://doi.org/10.3390/en11082081
Dante Ruiz Robles¹ , Vicente Venegas Rebollar¹ , Adolfo Anaya Ruiz² , Edgar Lenimirko Moreno Goytia¹ , Juan Ramón Rodríguez Rodríguez³
¹ Instituto Tecnológico de Morelia, División de Estudios de Posgrado e Investigación
² Instituto Tecnológico de Morelia, Ingeniería Eléctrica
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: medium frequency transformer, design methodology, nanocrystalline core, DAB
Abstract: Medium frequency transformers (MFTs) are a key component of DC–DC dual active bridge (DAB)-type converters. These technologies are becoming a quintessential part of renewable energy solutions, such as photovoltaic systems and wind energy power plants, as well as in modern power grid interfaces functioning as solid-state transformers in smart-grid environments. The weight and physical dimensions of an MFT are key data for the design of these devices. The size of an MFT is reduced by increasing its operating frequency. This reduction implicates higher power density through the transformer windings, as well as other design requirements distinct to those used for conventional 60/50 Hz transformers, therefore, new MFT design procedures are needed. This paper introduces a novel methodology for designing MFTs, using nanocrystalline cores, and tests it using an MFT–DAB lab prototype. Different to other MFT design procedures, this new design approach uses a modified version of the area-product technique, which consists of smartly modifying the core losses computation, and includes nanocrystalline cores. The core losses computation is supported by a full analysis of the dispersion inductance. For purposes of validation, a model MFT connected to a DAB converter is simulated in Matlab-Simulink (The MathWorks, v2014a, Mexico City, Mexico). In addition, a MFT–DAB lab prototype (1 kVA at 5 kHz) is implemented to experimentally probe further the validity of the methodology just proposed. These results demonstrate that the analytic calculations results match those obtained from simulations and lab experiments. In all cases, the efficiency of the MFT is greater than 99%.

Design of a System for Determinig the Temperature in the Presence of Magnetic Fluid a magnetic field
International Journal of Electronics Communication and Computer Engineering (IJECCE)
https://www.ijecce.org/index.php/issues?view=publication&task=show&id=1307
Fátima Moumtadi ¹ , Pavel Adolfo Figueroa Rodríguez¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Infrared Sensor, Semiconductor Sensor, Thermocouple, Magnetic Fluid
Abstract: The temperature increase curve is useful for the characterization of magnetic fluids which are used as a source of hyperthermia for cancer treatment or drug delivery. The present work was designed and implemented an electronic temperature measurement with an infrared sensor, a thermocouple and type sensor zener for magnetic fluids in the presence of an alternating magnetic field. The curve of temperature increase versus time was obtained. With the temperature curve and changing the concentration of nanoparticles fluid, curve specific absorption coefficient C_S in function of the concentration of ? nanoparticles was obtained.

Geochemical and petrological insights into the tectonic origin of the Transmexican Volcanic Belt
Earth-Science Reviews
https://doi.org/10.1016/j.earscirev.2016.12.006
Arturo Gómez Tuena¹ , Laura Mori ² , Susanne Straub ³
¹ Universidad Nacional Autónoma de México, Centro de Geociencias
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Columbia University, Lamont-Doherty Earth Observatory

Keywords: Subduction, Mantle, Continental crust, Arc magmatism, Mexico, Transmexican Volcanic Belt
Abstract: The Transmexican Volcanic Belt (TMVB) is the magmatic expression of one of the most complex convergent margins on the planet, and as such constitutes a prime location for testing emerging hypotheses on arc magma genesis and its influence on continental crust formation. By coupling an extensive geochemical and petrological database with an improved stratigraphic and geophysical framework, in this contribution we will examine the compositional diversity of the TMVB from the perspective of changes in subduction zone geometry and crustal thickness, as well as within the context of more subtle tectonic processes such as lithospheric foundering, slab detachment, fore-arc subduction erosion, crustal relamination and diapiric exhumation. We will illustrate that the compositional variability of mafic magmas across the region is an inherited characteristic of a geochemically enriched pre-subduction background mantle wedge, which has been variably overprinted by diverse chemical fluxes released from the slab at different thermal conditions. We will argue that the volumetrically dominant intermediate magmas in Mexico — from andesite to dacite and even some rhyolite — represent primary melts from hybrid slab and mantle sources, with no perceptible compositional influences from the overlying continental crust. These interpretations depart from conventional models that invoke intra-crustal differentiation and contamination of basalt to create intermediate magmas, and therefore have important implications to understanding the genesis of global continents.

Integral sliding-mode observation and control for switched uncertain linear time invariant systems: a robustifying strategy
Asian Journal of Control
https://doi.org/10.1002/asjc.1661
Rosalba Galván Guerra¹ , Leonid Fridman Golredich² , Rafael Iriarte ² , Juan Eduardo Velázquez Velázquez¹ , Martin Steinberger ³
¹ Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Graz University of Technology, Institute of Automation and Control

Keywords: Sliding modes, switched system, output feedback
Abstract: A robustifying methodology for switched systems with matched and unmatched uncertainties/perturbations and autonomous location transitions is presented. We avail of such methodology to design a control strategy based on integral sliding modes, thereby ensuring theoretically exact compensation of the matched uncertainties/perturbations and the minimization of the effects of the unmatched ones. An output integral sliding-mode control technique, based on a switched algebraic hierarchical observer is also proposed. This approach allows the theoretically exact compensation of the matched uncertainties/perturbations right after the first moment. The proposed approach is illustrated via numerical simulations.

Métodos de integración numérica de Newton aplicados en un problema de manejo de embalses
Ingeniería Investigación y Tecnología
http://dx.doi.org/10.22201/fi.25940732e.2018.19n2.016
Maritza Liliana Arganis Juárez¹ , Jesús Javier Cortés Rosas² , Miguel Eduardo González Cárdenas² , Víctor Damián Pinilla Morán² , Alfonso Salazar Moreno² , Salvador García Burgos²
¹ Universidad Nacional Autónoma de México, Instituto de Ingeniería
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Esquemas de integración numérica de Newton, esquema trapecial, esquema de simpson 1/3, esquema de simpson 3/8, volumen de almacenamiento de un embalse
Abstract: En este trabajo se presenta un estudio de caso para aplicar los conceptos de integración numérica de utilidad en las ciencias básicas de ingeniería. Se obtuvo el volumen de almacenamiento en un embalse, usando los esquemas de integración numérica de Newton (Trapecial, Simpson 1/3 y Simpson 3/8) a partir de los datos del tránsito de avenidas por el embalse de la presa "Las Cruces”, del proyecto hidroeléctrico de la Comisión Federal de Electricidad en el que se consideró como hidrograma de entrada la avenida de diseño para la obra de excedencias. Los resultados de los volúmenes calculados se compararon con los que reportó el programa que realiza el tránsito de la avenida, obteniéndose resultados conservadores con los métodos de integración Newton, respecto a la integración a través de rectángulos que realiza el programa de tránsito de la Comisión Federal de Electricidad.

Performance of CMORPH, TMPA, and PERSIANN rainfall datasets over plain, mountainous, and glacial regions of Pakistan
Theoretical and Applied Climatology
https://doi.org/10.1007/s00704-016-2027-z
Yawar Hussain ¹ , Frédéric Satgé ² , Muhammad B. Hussain ³ , Hernán Martínez Carvajal⁴ , Marie-Paule Bonnet ⁵ , Martín Cárdenas Soto⁶ , Henrique Llacer Roig² , Gulraiz Akhter ⁷
¹ University of Brasilia, Department of Civil and Environmental Engineering
² University of Brasilia, Institute of Geosciences
³ University of Lahore, Department of Physics
⁴ Universidad Nacional de Colombia, Facultad de Minas
⁵ Observatory for Environmental Change, Mixed Laboratory International
⁶ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁷ Quaid-i-Azam, Department of Earth Sciences

Keywords:
Abstract: The present study aims at the assessment of six satellite rainfall estimates (SREs) in Pakistan. For each assessed products, both real-time (RT) and post adjusted (Adj) versions are considered to highlight their potential benefits in the rainfall estimation at annual, monthly, and daily temporal scales. Three geomorphological climatic zones, i.e., plain, mountainous, and glacial are taken under considerations for the determination of relative potentials of these SREs over Pakistan at global and regional scales. All SREs, in general, have well captured the annual north-south rainfall decreasing patterns and rainfall amounts over the typical arid regions of the country. Regarding the zonal approach, the performance of all SREs has remained good over mountainous region comparative to arid regions. This poor performance in accurate rainfall estimation of all the six SREs over arid regions has made their use questionable in these regions. Over glacier region, all SREs have highly overestimated the rainfall. One possible cause of this overestimation may be due to the low surface temperature and radiation absorption over snow and ice cover, resulting in their misidentification with rainy clouds as daily false alarm ratio has increased from mountainous to glacial regions. Among RT products, CMORPH-RT is the most biased product. The Bias was almost removed on CMORPH-Adj thanks to the gauge adjustment. On a general way, all Adj versions outperformed their respective RT versions at all considered temporal scales and have confirmed the positive effects of gauge adjustment. CMORPH-Adj and TMPA-Adj have shown the best agreement with in situ data in terms of Bias, RMSE, and CC over the entire study area.

Procedures to determine the principal directions of kinematic performance in serial robots
Robotica
https://doi.org/10.1017/S0263574718000620
Ociel Flores Díaz¹ , Ignacio Juárez Campos¹ , Jorge Carrera Bolaños²
¹ Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Mecánica
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Principal velocity directios, serial mechanic systems, manipulability ellipses, maps of principal directions, systematic procedures
Abstract: Assume that the end-effector of a serial mechanism with n-degrees of freedom arrives at the position p0, where it can change arbitrarily the direction of its movement. The physical conditions imply that this change in direction also alters its velocity. The kinematic performance ellipse represents the velocities according to the new direction of the system, and thus solving the problem of which direction will correspond to a maximum or minimum (principal directions) magnitude of the corresponding velocity. In this paper, a new procedure to calculate these principal directions is presented and contrasted with two of the most common procedures employed in the field. All three procedures are considered in some detail, in order to understand their underlying concepts and, therefore, gain a deeper understanding of the physical situation. They are all proved in standard examples.

A 3D Hermite-based multiscale local active contour method with elliptical shape constraints for segmentation of cardiac MR and CT volumes
Medical & Biological Engineering & Computing
https://doi.org/10.1007/s11517-017-1732-9
Leiner Barba Jiménez¹ , Boris Escalante Ramírez¹ , Enrique Vallejo Venegas² , Fernando Arámbula Cosío³
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Hospital Ángeles del Pedregal, Cardiología
³ Universidad Nacional Autónoma de México, Centro de Ciencias Aplicadas y Desarrollo Tecnológico

Keywords: Hermite transform, directional and multiscale analysis, active cotour, cardiac MR/CT volumes, left ventricle segmentation
Abstract: Analysis of cardiac images is a fundamental task to diagnose heart problems. Left ventricle (LV) is one of the most important heart structures used for cardiac evaluation. In this work, we propose a novel 3D hierarchical multiscale segmentation method based on a local active contour (AC) model and the Hermite transform (HT) for LV analysis in cardiac magnetic resonance (MR) and computed tomography (CT) volumes in short axis view. Features such as directional edges, texture, and intensities are analyzed using the multiscale HT space. A local AC model is configured using the HT coefficients and geometrical constraints. The endocardial and epicardial boundaries are used for evaluation. Segmentation of the endocardium is controlled using elliptical shape constraints. The final endocardial shape is used to define the geometrical constraints for segmentation of the epicardium. We follow the assumption that epicardial and endocardial shapes are similar in volumes with short axis view. An initialization scheme based on a fuzzy C-means algorithm and mathematical morphology was designed. The algorithm performance was evaluated using cardiac MR and CT volumes in short axis view demonstrating the feasibility of the proposed method.

A seismogeodetic amphibious network in the Guerrero Seismic Gap, Mexico
Seismological Research Letters
https://doi.org/10.1785/0220170173
Víctor M. Cruz Atienza¹ , Yoshihiro Ito ² , Vladimir Kostoglodov ¹ , Vala Hjörleifsdóttir ¹ , Arturo Iglesias Mendoza¹ , Josué Tago Pacheco³ , Marco Calò ¹ , Jorge Real Pérez¹ , Allen Husker ¹ , Ide Satoshi ⁴ , Takuya Nishimura ² , Masanao Shinohara ⁴ , Carlos Mortera Gutierrez¹ , Emmanuel Soliman García² , Kido Motoyuki ⁵
¹ Universidad Nacional Autónoma de México, Instituto de Geofísica
² Kyoto University, Disaster Prevention Research Institute
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁴ Kyoto University, School of Science
⁵ Tohoku University, Research Center for Prediction of Earthquakes and Volcanic Eruptions

Keywords: earthquakes, East Pacific, Guerrero Mexico, Northeast Pacific, Pacific Ocean, Mexico, North Pacific, Middle America Trench, tectonics
Abstract: The historical record of large subduction earthquakes in Guerrero, Mexico, reveals the existence of an ~230-km length segment below the coast where no major rupture has occurred in the past 60 years. Reliable quantification of the hazard associated with such a seismic gap is urgently needed for risk mitigation purposes by means of state-of-the-art observations and modeling. In this article, we introduce and quantitatively assess the first seismogeodetic amphibious network deployed in Mexican and Central American soils that will provide the opportunity to achieve this goal in the near future. Deployed in 2017, the network is the result of a collaborative effort between Mexican and Japanese scientists. It consists of 15 onshore broadband and 7 ocean-bottom seismometers, 33 Global Positioning System (GPS) stations, 7 ocean-bottom pressure gauges, and 2 GPS-acoustic sites, most of them installed within the Guerrero seismic gap. Initial data from the network revealed the occurrence of a 6-month-long slow-slip event in Guerrero, starting in May and ending in October 2017. To illustrate the performance of the various instruments, we also present the first ocean-bottom pressure and GPS-acoustic measurements in Mexico; the latter was obtained by means of an autonomous Wave Glider vehicle. The ground motion of the devastating 19 September 2017 Mw 7.1 earthquake in central Mexico is presented as well. Nominal resolution of the seismogeodetic network is estimated through different synthetic inversion tests for tomographic imaging and the seismic coupling (or slow-slip) determination on the plate interface. The tests show that combined onshore and offshore instruments should lead to unprecedented results regarding the seismic potential (i.e., interface coupling) of the seismic gap and the Earth structure from the Middle America trench up to 70-km depth across the Guerrero state.

Electroosmotic pumping between two immiscible electrical conducting fluids controlled by interfacial phenomena
Journal of Applied Fluid Mechanics
https://dx.doi.org/10.29252/jafm.11.03.27778
Adelaido Ildefonso Matías Domínguez¹ , Oscar Eladio Bautista Godínez² , Federico Méndez Lavielle¹ , Juan P. Escandón Colín²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Immiscible conducting fluids, Electroosmosis, Circular microcapillary, Maxwell stress, Interfacial stress
Abstract: In this study, the isothermal electroosmotic flow of two immiscible electrical conducting fluids within a uniform circular microcapillary was theoretically examined. It was assumed that an annular layer of liquid adjacent to the inside wall of the capillary exists, and this in turn surrounds the inner flow of a second liquid. The theoretical analysis was performed by using the linearized Poisson-Boltzmann equations, and the momentum equations for both fluids were analytically solved. The interface between the two fluids was considered uniform, hypothesis which is only valid for very small values of the capillary number, and shear and Maxwell stresses were considered as the boundary condition. In addition, a zeta potential difference and a charge density jump were assumed at the interface. In this manner, the electroosmotic pumping is governed by the previous interfacial effects, a situation that has not previously been considered in the specialized literature. The simplified equations were nondimensionalized, and analytical solutions were determined to describe the electric potential distribution and flow field in both the fluids. The solution shows the strong influence of several dimensionless parameters, such as µr, er, , and , and , on the volumetric flow. The parameters represent the ratio of viscosity, the ratio of electric permittivity of both fluids, the dimensionless zeta potential of the microcapillary wall, the dimensionless charge density jump and charge density between both fluids, and the electrokinetic parameters, respectively.

Fluid dynamics in naturally fractured tectonic reservoirs
Journal of Petroleum Exploration and Production Technology
https://doi.org/10.1007/s13202-017-0320-8
Nelson Barros Galvis¹ , Fernando Samaniego Verduzco² , Héber Cinco Ley²
¹ Instituto Mexicano del Petróleo,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Extensional and tectonic fractures, Cole–Hopf transformation, Couette’s and Darcy’s flow, Fluid dynamics, Nonlinear fluid flow, Analytical solution
Abstract: This study presents analytical models for naturally fractured tectonic reservoirs (NFTRs), which essentially correspond to type I fractured reservoirs, including the effects of the nonlinear gradient term for radial flow, single phase (oil), for constant rate in an infinite reservoir. Using an exact solution of Navier–Stokes equation and Cole–Hopf transform, NFTRs have been modeled. Our models are applied for fissured formations with extensive fractures. Smooth and rough extension fractures were analyzed using single and slab flow geometries. The motivation for this study was to develop a real and representative model of a NFTR, with extension fractures to describe its pressure behavior. A discussion is also presented with field examples, regarding the effect of a quadratic gradient term and the difference between the nonlinear and linear pressure solutions, comparing the Darcy laminar flow equation, with the exact solution of the Navier–Stokes equation applied to the diffusion equation and boundary conditions in wellbore.

On-line estimation of switched reluctance motor parameters
International Journal of Adaptive Control and Signal Processing
https://doi.org/10.1002/acs.2877
Missie Aguado Rojas¹ , Paul Rolando Maya Ortíz² , Gerardo Espinosa Pérez²
¹ Université Paris-Sud,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: parameter estimation, parameter identification, switched reluctance motor modeling, switched reluctance motors
Abstract: This paper addresses the problem of on-line parameter estimation of switched reluctance motors and provides, to the best of the authors' knowledge, the first result that takes into account the dynamics of both electrical and mechanical subsystems. Based on a widely-used standard model of the motor and establishing a reasonable structure for modeling the unknown load torque, a linear parametric model is derived and a 2-stage identification scheme is proposed and implemented with the recursive least-squares algorithm with forgetting factor. It is assumed that stator voltages and currents and rotor position and speed are available through measurements. Numerical simulations and experimental tests are included for a 3-phase 12/8 switched reluctance motor. The results show a good performance of the proposed methodology, and the estimated parameters are validated through their use in a closed-loop control scheme. Key features of the proposed solution are that it does not rely on locked-rotor tests nor does it assume previous knowledge of the magnetization curves of the motor. The estimation scheme is intended to improve the performance and efficiency of currently available control algorithms, and it is potentially useful for the design of selfcommissioning switched reluctance drives, ie, drives that can automatically adjust the controller parameters for a wide range of motors and loads.

Performance Comparison of PI Controllers for PMSM Using Bio-Inspired Algorithms
IEEE Latin America Transactions
https://doi.org/10.1109/TLA.2018.8327429
Omar Aguilar Mejía¹ , Raúl Sosa Cortés² , Carlos Enríquez Ramírez³ , José Luis Templos Santos² , Hertwin Minor Popocatl¹ , Rubén Tapia Olvera⁴
¹ Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrados
² Universidad Politécnica de Tulancingo, División de Investigación y Posgrado
³ Universidad Politécnica de Tulancingo, División de Ingenierías
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bio-inspired models, PI controller, PMSM, Swarm intelligence
Abstract: A Proportional-Integral (PI) controller is a system designed to diminish the error between the desired reference value and the measured variable of the process to be regulated. The PI controller works according to two input parameters that must be calculated by a tuning process. In this work, the process is performed using intelligent swarm algorithms to seek for optimal parameters of PI controller. Three reactive, nature-inspired algorithms (bat, whale optimization and cuckoo search), were used to tune the PI controller. The control scheme based on linear regulators is used to improve the performance of the permanent magnet synchronous motor (PMSM) and to regulate the rotor speed to a desired reference value. In order to validate the effectiveness of the controller, simulation is performed under constant load condition, varying load condition and varying set speed conditions of the PMSM.

Uniform fragility spectra for the performance-based seismic design of structures considering variabilities in structural properties
Earthquake Engineering & Structural Dynamics
https://doi.org/10.1002/eqe.3038
Mauro Niño Lázaro¹ , Gustavo Ayala ² , Saúl López ³
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería
³ Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Acatlán

Keywords: performance-based seismic design, uniform fragility design spectra, variable structural properties
Abstract: This paper presents a new methodology based on structural performance to determine uniform fragility design spectra, i.e., spectra with the same probability of exceedance of a performance level for a given seismic intensity. The design spectra calculated with this methodology provide directly the lateral strength, in terms of yield- pseudo-accelerations, associated with the rate of exceedance of a specific ductility characterizing the performance level for which the structures will be designed. This procedure involves the assessment of the seismic hazard using a large enough number of seismic records of several magnitudes; these records are simulated with an improved empirical Green function method. The statistics of the performance of a single degree of freedom system are obtained using Monte Carlo simulation considering the seismic demand, the fundamental period, and the strength of the structure as uncertain variables. With these results, the conditional probability that a structure exceeds a specific performance level is obtained. The authors consider that the proposed procedure is a significant improvement to others considered in the literature and a useful research tool for the further development of uniform fragility spectra that can be used for the performance-based seismic design and retrofit of structures.

Velocity observer design for the consensus in delayed robot networks
Journal of the Franklin Institute
https://doi.org/10.1016/j.jfranklin.2018.07.001
Marco Antonio Arteaga Pérez¹ , Emmanuel Nuño ²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad de Guadalajara, Centro Universitario de Ciencias Exactas e Ingeniería

Keywords:
Abstract: The consensus problem for networks of multiple agents consists in reaching an agreement between certain coordinates of interest using a distributed controller. It may be desirable that all the agents find a consensus at a given desired leader coordinate (Leader Follower Consensus Problem LFCP), or it may be only necessary that they agree at a certain coordinates value (Leaderless Consensus Problem LCP). Consensus has many practical applications in robot networks systems, where the interconnection of the agents may present variable time delays, hence rendering the stability analysis and control design more complex. Another problem that may arise is the possible lack of velocity measurements. In this work, a Proportional plus damping injection (P + d) controller together with a linear velocity observer is introduced. Our approach is able to solve both the LFCP and the LCP in networks of robots modeled as undirected weighted graphs with unknown asymmetric (bounded) variable time delays. Local (semi global) asymptotic stability is proven and simulation results are provided to test the performance of the proposed scheme.

A Suite of Exercises for Verifying Dynamic Earthquake Rupture Codes
Seismological Research Letters
https://doi.org/10.1785/0220170222
Ruth A. Harris ¹ , Michael Barall ² , Brad Aagaard ¹ , Shou Ma ³ , Daniel Roten ³ , Kim Olsen ³ , Benchun Duan ⁴ , Dunyu Liu ⁴ , Bin Luo ⁴ , Kangchen Bai ⁵ , Jean Paul Ampuero ⁵ , Yoshihiro Kaneko ⁶ , Alice Agnes Gabriel ⁷ , Kenneth Duru ⁷ , Thomas Ulrich ⁷ , Stephanie Wollherr ⁷ , Zheqiang Shi ⁸ , Eric Dunham ⁹ , Sam Bydlon ⁹ , Zhenguo Zhang ¹⁰ , Xiaofei Chen ¹⁰ , Surendra Nadh Somala¹¹ , Christian Pelties ⁷ , Josué Tago Pacheco¹² , Víctor M. Cruz Atienza¹³ , Jeremy Edward Kozdon ¹⁴ , Eric Daub ¹⁵ , Khurram Aslam ¹⁵ , Yuko Kase ¹⁶ , Kyle Withers ¹⁷ , Luis Dalguer ¹⁸
¹ United States Geological Survey,
² Invisible Software,
³ San Diego State University, Department of Geological Sciencies
⁴ Texas A&M University, Department of Geology & Geophysics
⁵ California Institute of Technology, Seismological Laboratory
⁶ GNS Science,
⁷ Ludwig Maximilians Universität München, Department of Earth and Environmental Science
⁸ Tokio Marine Technologies LLC, Risk Modeler
⁹ Stanford University, Department of Geophysics
¹⁰ Southern University of Science and Technology, Department of Earth and Space Sciences
¹¹ Indian Institute of Tecnology Hyderabad, Department of Civil Engineering
¹² Universidad Nacional Autónoma de México, Facultad de Ingeniería
¹³ Universidad Nacional Autónoma de México, Instituto de Geofísica
¹⁴ Naval Postgraduate School, Department of Applied Mathematics
¹⁵ University of Memphis, Center for Earthquake Research and Information
¹⁶ National Institute of Advanced Industrial Science and Technology , Geological Survey of Japan
¹⁷ United States Geological Survey, Geologic Hazards Science Center
¹⁸ Swissnuclear,

Keywords: data processing, earthquakes, faults
Abstract: We describe a set of benchmark exercises that are designed to test if computer codes that simulate dynamic earthquake rupture are working as intended. These types of computer codes are often used to understand how earthquakes operate, and they produce simulation results that include earthquake size, amounts of fault slip, and the patterns of ground shaking and crustal deformation. The benchmark exercises examine a range of features that scientists incorporate in their dynamic earthquake rupture simulations. These include implementations of simple or complex fault geometry, off-fault rock response to an earthquake, stress conditions, and a variety of formulations for fault friction. Many of the benchmarks were designed to investigate scientific problems at the forefronts of earthquake physics and strong ground motions research. The exercises are freely available on our website for use by the scientific community.

An online algebraic estimation approach of parameters and variable mechanical torque in shunt DC motors
International Transactions on Electrical Energy Systems
https://doi.org/10.1002/etep.2474
Francisco Beltrán Carbajal¹ , Rubén Tapia Olvera² , Omar Aguilar Mejía³ , Antonio Favela Contreras⁴ , Irvin López García¹
¹ Universidad Autónoma Metropolitana, Unidad Azcapotzalco
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrado
⁴ Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias

Keywords: adaptive control, parametric estimation, shunt DC motor, torque estimation
Abstract: Classical control design methods have been successfully applied to several practical engineering systems for regulation tasks around a desired equilibrium operation state. Nevertheless, real-time information of some system parameters and mechanical torque could be required to guarantee an efficient and robust control performance for variable operation conditions. In this paper, an online and algebraic scheme is proposed for simultaneous estimation of parameters and variable mechanical load torque for nonlinear shunt DC motors. An adaptive PI velocity tracking control scheme is also described to verify the effectiveness and efficiency of the parametric estimation approach. Control dynamic gains are computed online by applying a B-spline neural network algorithm. Computational simulation results confirm the fast estimation of parameters and variable mechanical torque.

Applications and Contributions of Physics to the Surface Treatment Process of Materials. Part I. Thermal Spray Processes
European Journal of Engineering Research and Science
https://doi.org/10.24018/ejers.2018.3.4.676
Omar Álvarez Brito¹ , Arturo Barba Pingarrón² , Raúl Valdéz Navarro² , R. González ² , Alba Covelo Villar² , Miguel Ángel Hernández Gallegos² , R. Rojas ²
¹ Universidad Nacional Autónoma de México, Instituto de Energías Renovables
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Applications of Physics, Surface Treatment of Materials, Thermal Spray Process
Abstract: The objective of these two works is to show how a series of principles and concepts of Physics are applied (which are taught in the areas of Basic Sciences in Engineering careers), in various processes that are used to modify the surface of materials and thus provide them with improved properties particularly related to wear, fatigue and corrosion resistance, with the purpose that engineering students have greater evidence of practical applications and, therefore, of the importance of Physics for development of these technologies. As an example, in this first article, the Thermal Spray processes are presented and it is shown how Physics concepts are applied and have a prominent role both in the design and in the construction of the equipment with which they are made, as well as in the own generation of surface treatments. This is intended to give a sample and evidence the usefulness of Physics in this type of process to both students and teachers.

Applications and Contributions of Physics to the Surface Treatment Process of Materials. Part II. Other Treatments
European Journal of Engineering Research and Science
https://doi.org/10.24018/ejers.2018.3.4.677
Omar Álvarez Brito¹ , Arturo Barba Pingarrón² , R. Rojas ² , R. González ² , Raúl Valdéz Navarro² , Alba Covelo Villar² , Miguel Ángel Hernández Gallegos²
¹ Universidad Nacional Autónoma de México, Instituto de Energías Renovables
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Applications of Physics, Surface Treatment of Materials, Use of Concentrated Energy
Abstract: In this second part another group of processes of surface treatment of materials in which has been employed a series of principles of the Physics are reviewed. Using technologies that employ these principles it is possible to modify the surface of materials in order to obtain improvements in their behavior, specially in regard to increasing their corrosion, wear or fatigue resistance. In particular, this work describes the processes of flame and induction hardening, surface treatments using laser beam, treatments that use concentrated solar energy and finally the processes of physical vapor deposition. All of them of industrial application, with the exception of the use of concentrated solar energy which, however, has an important potential due to the current situation of the renewable energies.

Control of Bilateral Teleoperators with Time-Delays Using Only Position Measurements
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.3903
Emmanuel Nuño ¹ , Marco Antonio Arteaga Pérez² , Gerardo Espinosa Pérez²
¹ Universidad de Guadalajara, Centro Universitario de Ciencias Exactas e Ingeniería
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: bilateral teleoperators, robot control, time delays
Abstract: A major drawback in the control of bilateral teleoperators is time delays. The nature of the communication channel that interconnects the local and the remote manipulators imposes these delays, which can be time-varying. Several commercially available robots do not incorporate velocity sensors, and velocities are usually estimated using dirty derivatives. In this paper, we are interested in the control of bilateral teleoperators with variable time delays and without requiring velocity measurements. The proposal makes use of a second-order dynamical controller that backpropagates damping to the local and the remote manipulators. If sufficient damping is injected in the controller and under the common passivity assumption of the human operator and the environment, it is proved that position errors and velocities are bounded. Invoking Barbalat's lemma, when the human and the environment do not inject forces in the system, it is shown that position error and velocities globally asymptotically converge to zero. A simulation comparison with other two control techniques shows the performance of the novel proposal. Experimental results evidence the robustness of the proposed scheme to interconnecting time delays.

Design of a Hearing Auxiliary for Bilateral Hypoacusia
International Journal of Engineering Science and Research Technology
https://doi.org/10.5281/zenodo.1165570
Alan Castañeda Ramírez¹ , Fátima Moumtadi ¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bilateral Hypoacusia, auditory aid, audio amplifier, three band equalizer, hearing aid
Abstract: In this work a box type hearing aid was designed as a convenient and low cost alternative for people with bilateral hearing loss. The hearing aid will be equipped with the following stages: a microphone to receive the acoustic signals, a preamplifier with automatic gain control to protect the user from excessive sounds, a 3-band equalization (bass, mid and treble) for each ear canal, a volume control for each and finally a 3.5mm jack output for the user to equip this device, with the headphones of his choice.

Lyapunov-based design for a class of variable-gain 2nd-sliding controllers with the desired convergence rate
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.4310
Emmanuel Cruz Zavala¹ , Jaime Alberto Moreno Pérez² , Leonid Fridman Golredich³
¹ Universidad de Guadalajara, Centro Universitario de Ciencias Exactas e Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: finite-time stability, fixed-time stability, Lyapunov-based methods, second-order sliding mode control, variable-gain controllers
Abstract: The aim of this paper is to propose a novel family of variable-gain second-order sliding mode controllers capable of dealing with uncertainties and disturbances that grow with the state. The proposed family provides exact compensation of perturbations having a known upper bound and generalizes some sliding controllers reported in the literature. A novelty of this work is that the designer is able to choose the desired convergence rate: semiglobal/global finite-time or fixed-time. The analysis and control design is completely based on a strict Lyapunov function, leading to an effective procedure to tune the gains.

Prograding low-density turbidite systems and oil traps at the Lower Paleogene Chicontepec Foreland Basin, East-Central Mexico
Ingeniería Investigación y Tecnología
http://dx.doi.org/10.22201/fi.25940732e.2018.19n4.035
Joaquín Eduardo Aguayo Camargo¹ , Noé Santillán Piña¹ , Javier Arellano Gil¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Gulf of Mexico, tertiary basin, tectonics, stratigraphy, gravity flows, sedimentary facies, oil trapping
Abstract: The Lower Paleogene Chicontepec Foreland Basin at the southern region of the Tertiary Tampico-Misantla Basin at East-Central Mexico, resulting from the loading pressure of the uplifted and thrust-folded front of the Sierra Madre Oriental, on the passive, unfolded and thermally in subsidence Cretaceous basement, during the northeastward tectonic stresses from the Laramide Orogeny, against the Tuxpan Island eastern. The foreland basin consists stratigraphically of complex low density turbidite systems, being their detached and non-channelized outer-fan lobe facies the most conspicuous, composite by disperse and discontinue sandy lenses with tight and highly cemented calcareous lithofacies, micro-fractured and with micro-vugs by dissolution. The hydrocarbons flowed vertically from the underlay Cretaceous and Upper Jurassic rocks through the NW-SE dextral transpressive strike-slip fault planes and fractures, then spread laterally toward the micro-fractured sandy lenses and within the unconformable erosive surfaces, bounding the depositional systems (systems tracts), at different levels of the Chicontepec stratigraphic column, in a hybrid petroleum system with low permeability unconventional reservoirs.

‘Illuminating’ the interior of Kukulkan's Pyramid, Chichén Itzá, Mexico, by means of a non-conventional ERT geophysical survey
Journal of Archaeological Science
https://doi.org/10.1016/j.jas.2017.12.006
Andrés Tejero Andrade¹ , Denisse L. Argote Espino² , Gerardo Cifuentes Nava³ , Juan Esteban Hernández Quintero³ , René E. Chávez Segura³ , Alejandro García Serrano¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Instituto Nacional de Antropología e Historia, Dirección de Estudios Arqueológicos
³ Universidad Nacional Autónoma de México, Instituto de Geofísica

Keywords: ERT, Pyramid of Kukulkan, Constructive phases, Chichén Itzá, Mexico
Abstract: Chichén Itzá, located in the north-central portion of the Yucatán Peninsula, is one of the major pre-Hispanic cities established in the southern lowlands of Mexico. The main objective of this investigation was to "unveil” the interior of the pyramid of El Castillo, also known as the Temple of Kukulkan, an emblematic structure in this archaeological site. To that end, 828 flat electrodes were deployed around each of the 9 bodies that compose the pyramid, including the base of the structure. A dataset consisting of 37,548 observations was obtained. A precise topographic control for each electrode was carried out and introduced in the inversion model. The mathematical process to compute a final 3D model was made possible by taking 9 observation levels (33,169 measurements) into account, due to computational limitations. The results showed the existence of two older pyramids within the main Mayan building and provided important information regarding our understanding of this Mayan civilization. Future archaeological studies in the older substructure could reveal information about early settlement on this site, its evolution in time and its cultural influences.

A Comparative Study on Discrete Shmaliy Moments and Their Texture-Based Applications
Mathematical Problems in Engineering
https://doi.org/10.1155/2018/1673283
Germán González ¹ , Rodrigo Nava ² , Boris Escalante Ramírez¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Luxembourg Institute of Science and Technology,

Keywords:
Abstract: In recent years, discrete orthogonal moments have attracted the attention of the scientific community because they are a suitable tool for feature extraction. However, the numerical instability that arises because of the computation of high-order moments is the main drawback that limits their wider application. In this article, we propose an image classification method that avoids numerical errors based on discrete Shmaliy moments, which are a new family of moments derived from Shmaliy polynomials. Shmaliy polynomials have two important characteristics: one-parameter definition that implies a simpler definition than popular polynomial bases such as Krawtchouk, Hahn, and Racah; a linear weight function that eases the computation of the polynomial coefficients. We use IICBU-2008 database to validate our proposal and include Tchebichef and Krawtchouk moments for comparison purposes. The experiments are carried out through 5-fold cross-validation, and the results are computed using random forest, support vector machines, naïve Bayes, and k-nearest neighbors classifiers.

Asymptotic Solution for the Reflection of Long Water Waves by Asymmetric Convergent/Divergent Harbours
Journal of Coastal Research
https://doi.org/10.2112/JCOASTRES-D-16-00224.1
A. Mora ¹ , Eric Gustavo Bautista Godínez² , Federico Méndez Lavielle³ , M. Barbosa López⁴
¹ Tecnológico de Estudios Superiores de Ecatepec,
² Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁴ Instituto Politécnico Nacional, ESIME

Keywords: asymmetric harbour, long wave, Slender harbour, wave reflection
Abstract: In this work, formulas for the reflection and transmission coefficients of linear long water waves propagating along a slender harbour composed of an asymmetric convergent/divergent region connected to uniform inlet and outlet regions are obtained. The governing equation is solved using the Wentzel-Kramers-Brillouin singular perturbation technique. A better sheltering function of the harbour is found for a divergent harbour with asymmetric variations in width. For convergent harbours, the largest values of the reflection coefficient are obtained for the limit in which the length of the harbour is of the same order of magnitude as the wavelength. A zero-reflection phenomenon occurs for a convergent symmetric harbour with a linearly varying width and a parabolic depth profile. The results reveal that in the presence of a linear transition in either width or depth, the reflection coefficients exhibit oscillating behaviour. The present mathematical model is compared with a simple numerical solution and with another analytical solution expressed in terms of Bessel functions. The formulas are also checked by considering an energy identity, which is satisfied to very good accuracy. Therefore, the deduced formulas can serve as a preliminary means of identifying which harbour geometries can significantly amplify or attenuate the amplitudes of water waves.

Cenozoic magmatism of the Sierra Madre del Sur and tectonic truncation of the Pacific margin of southern Mexico
Earth-Science Reviews
https://doi.org/10.1016/j.earscirev.2017.01.010
Dante J. Morán Zenteno¹ , Barbara M. Martiny ¹ , Luigi Solari ² , Laura Mori ³ , Laura Luna González¹ , Enrique Alejandro González Torres³
¹ Universidad Nacional Autónoma de México, Instituto de Geología
² Universidad Nacional Autónoma de México, Centro de Geociencias
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Southern Mexico, Sierra Madre del Sur, Margin truncation, Subduction erosion, Chortís
Abstract: In southern Mexico, the Sierra Madre del Sur (SMS) preserves the record of a long-lived magmatic arc that vanished diachronically during Paleogene-early Miocene time, decreasing in age to the southeast. The magmatic record consists of a coastal plutonic belt dominated by granites and granodiorites with minor mafic and intermediate intrusions and an inland volcanic belt dominated by intermediate and silicic volcanic centers. The juxtaposition of the plutonic belt with the trench indicates the removal of most of the Paleogene forearc during the Oligocene. Abundant evidence indicates that subduction erosion played a significant role in the reconfiguration of the continental margin of southern Mexico following cessation of magmatism. This is evident in the subsidence of continental segments contiguous to the present trench and the loss of lower continental crust as inferred from the present shape of the wedge, as well as in the estimations of the former crustal thickness based on geobarometry of the exposed levels of plutonic complexes. The Late Cretaceous-Cenozoic decreasing age trend in the SMS shows three time intervals in which magmatism ceased at different rates. The general southeastward younging trend of magmatism, as well as the left-lateral shear zones of the central and coastal zones of the Sierra Madre del Sur, in combination with constraints imposed by the prevalent model of the Caribbean plate evolution have been invoked to consider the Chortís block as the removed segment during margin truncation. The main drawbacks of this model are the mismatch in the chronology of migmatitic complexes of northern Chortís and the Xolapa terrane in the continental margin of southern Mexico, and the presence of the Late Cretaceous to present unperturbed marine sequence in the Gulf of Tehuantepec in the assumed trajectory of the Chortís block. These considerations and the subduction erosion evidence suggest a more complex scenario than having Chortís juxtaposed immediately adjacent to the present-day margin. There are alternative possibilities to explain removal of the forearc, ranging from a western provenance for the Chortís block, as has been suggested in other models, to intermediate positions for Chortís with a more southern trajectory with respect to the present-day trench. Such a trajectory would leave a broad zone with shear strain structures more susceptible to removal by subduction erosion after the passage of the trench-trench transform triple junction. This would reconcile the evidence of subduction erosion and the indications of the northwestern provenance of the Chortís block.

Current-Sensorless VSC-PFC Rectifier Control with Enhance Response to Dynamic and Sag Conditions Using a Single PI Loop
IEEE Transactions on Power Electronics
https://doi.org/10.1109/TPEL.2017.2749213
Mario A. Santoyo Anaya¹ , Juan Ramón Rodríguez Rodríguez² , Edgar Lenimirko Moreno Goytia¹ , Vicente Venegas Rebollar¹ , Nadia María Salgado Herrera³
¹ Instituto Tecnológico de Morelia, División de Estudios de Posgrado e Investigación
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Eléctrica

Keywords: Rectifiers, Voltage control, Reactive power, Power quality, Proposals, Switches, Modulation
Abstract: This paper presents the design, modeling, implementation, and experimental results of an advanced current-sensorless control scheme for voltage source converter-power factor correction rectifiers. This proposal is aimed to reduce the complexity of the control while maintaining desirable features for ac/dc conversion, such as unity power factor, low total harmonic distortion in input current, continuous regulation of the dc voltage even facing ac voltage sags and dynamic load changes. Unlike other proposals, this scheme has a single feedback proportional-integral loop, uses few mathematical operations, and the dq0 reference frame is not included in the control scheme. These characteristics simplify the implementation of the proposed control thus improving its efficiency. The theoretical analysis and simulation validate the technical feasibility of the proposed control, and finally, various cases of study and experimental results obtained with a laboratory scale-down prototype are presented to confirm the viability and performance of the control.

Neutronic study of an ASTRID-like fast reactor core with thorium-based fuel
Nuclear Engineering and Design
https://doi.org/10.1016/j.nucengdes.2018.09.007
Daniel Escorcia Ortiz¹ , Juan Luis François Lacouture¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: ASTRID, Thorium, Sodium fast reactors, Breeding
Abstract: In this work the utilization of thorium was investigated in a sodium-cooled ASTRID-like fast reactor core. Two thorium fueled strategies were analyzed and compared with the reference core in which the fuel vector is composed of a mixture of U-Pu MOX fuel. For the first strategy, all uranium isotopes in the fertile zone (depleted uranium) were replaced by a mixture of 232Th/233U, leaving the fissile zone with the U-Pu MOX composition. For the second strategy, the whole core, that is, the fertile and fissile zones were loaded with a mixture of 232Th/233U. The Monte Carlo MCNP6 code with the ENDF/B-VII.0 cross section library was used to perform the calculations. Six neutronic parameters were analyzed for each fuel strategy: the neutron energy spectrum, the effective neutron multiplication factor (keff) for an operating cycle of 365 days, the Doppler constant, the reactivity effect of the coolant density, the effective delayed neutrons fraction (ßeff) and the shutdown margin. The main isotopes evolution and the radial power distribution were also analyzed. Results show that the energy spectrum is harder with high thorium fraction, i.e. in the case with 232Th/233U in the whole core. The behavior of keff along the operating cycle of the reference core and that of the case with 232Th/233U in the fertile zone is very similar, getting the second one a slightly higher keff at the end of cycle. The keff with 232Th/233U in the whole core has a significant loss in reactivity and need further research. As for the isotopes, in the reference core 239Pu is bred, the same happens with 233U in the core with 232Th/233U in the fertile zone. This does not happen with 232Th/233U in the whole core. The Am and Cm actinides concentrations are lower with 232Th/233U in the fertile zone than in the reference core and are completely absent with 232Th/233U in the whole core. For all the configurations the Doppler constant and the reactivity effect of coolant density behave well, as the keff drops with temperature raise or with void raise. In the case of sodium voiding, a better performance is observed with 232Th/233U in the whole core. The power distribution is alike in all core configurations, having a ring with the higher power in the outer fuel region. The full 232Th/233U fuel configuration have the more even power distribution. All core configurations have similar ßeff and show a satisfactory shutdown margin, as it is higher than 1% dk/k at the beginning of cycle.

Time-Domain Numerical Simulation of Electronic Circuits and Surface Acoustic Wave Devices using their Admittance Parameters
IEEE Transactions on computer-aided design of integrated circuits and systems
https://doi.org/10.1109/TCAD.2018.2818732
Jaime Octavio Guerra Pulido¹ , Pablo Pérez Alcaraz¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Integrated circuit modeling, Delay lines, Surface acoustic waves, Oscillators, Surface acoustic wave devices, Electronic circuits, Time-domain analysis
Abstract: We present a method to calculate the transient response of electronic circuits when these contain elements whose behaviors are given by their admittance matrices in the frequency domain. After describing this method in detail, an amplifier with resistive networks and interdigital transducers using specific input signals was proposed to test the method, and these results agreed when compared with those obtained with a simulation program with integrated circuit emphasis (SPICE)-based program. Besides, the simulation of two oscillators are presented; the first has a feedback network consisting of serial-connected equivalent circuits of crystals, and the second uses a feedback network with a surface acoustic wave (SAW) delay line. For the first oscillator, the waveforms obtained using this method and a SPICE-based program considering two different numerical integration methods were compared, and they looked similar, but all signals have different rise times because these simulations are very sensitive to inherent numerical errors. The simulation of a SAW delay line oscillator and its input and output voltages and currents were obtained, and its fundamental frequency was 77.77 MHz. These simulated results were validated experimentally through the oscillation frequency, which was found using the $-parameters of the amplifier and the delay line and an oscillation criterion, and it was measured directly in the circuit. The experimental oscillation frequencies were 76.9 and 77.5 MHz, respectively, and the errors between simulation and experimentation were approximately 1%.

Valorization of Metallurgical Slag for the Treatment of Water Pollution: An Emerging Technology for Resource Conservation and Re-utilization
Journal of Sustainable Metallurgy
https://doi.org/10.1007/s40831-018-0158-4
Bertha María Mercado Borrayo¹ , José Luis González Chávez² , Rosa María Ramírez Zamora¹ , Rafael Schouwenaars Franssens³
¹ Universidad Nacional Autónoma de México, Instituto de Ingeniería
² Universidad Nacional Autónoma de México, Facultad de Química
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Waste water, Drinkable water, Copper slag, Ferrous slag, Advanced oxidation processes, Sorption
Abstract: Valorization of metallurgical slag as a material for the treatment of polluted water resources has a threefold environmental impact and enhances the sustainability of both the metallurgical industry and water-treatment processes. Firstly, the amount of waste slag to be disposed of is reduced; secondly, expensive chemical reagents required for water treatment are saved; thirdly, water resources, which are unfit for human consumption or irrigation, can be accessed. This paper reviews the use of iron, steel, and copper slag in environmental applications. While this may include air and soil remediation, the focus is on water pollution control, demonstrating the effectiveness of slag for the removal of inorganic, organic, and biological contaminants. Iron and steel slags are mainly used as sorbents or as reagents for the co-precipitation of contaminants. Copper slag finds applications in advanced chemical oxidation processes with high efficiency. The corresponding methods are emerging technologies, which are developed to minimize the costs (investment, operational, and maintenance) of pollutant removal and are often focused on small-scale processes or local treatments, which are important in the sustainable development of local communities in developing economies.

A generalized passivity-based control approach for power compensation in distribution systems using electrical energy storage systems
Journal of Energy Storage
https://doi.org/10.1016/j.est.2018.01.018
Oscar Danilo Montoya Giraldo¹ , Alejandro Garces ² , Gerardo Espinosa Pérez³
¹ Universidad Tecnológica de Bolivar,
² Universidad Tecnológica de Pereira,
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Electrical energy storage systems (EESS), Generalized mathematical model, Interconnection and damping assignment passivity-based control (IDA-PBC), Supercapacitor energy storage (SCES), Superconducting magnetic energy storage (SMES)
Abstract: This paper presents a generalized interconnection and damping assignment passivity-based control (IDA-PBC) for electric energy storage systems (EESS) such as: superconducting magnetic energy storage (SMES) and supercapacitor energy storage (SCES). A general framework is proposed to represent the dynamical behavior of EESS interconnected to the electrical distribution system through forced commutated power electronic converters. A voltage source converter (VSC) and a pulse-width modulated current source converter (PWM-CSC) are used to integrate SCES and SMES systems to the electrical power systems respectively. The proposed control strategy allows active and reactive power interchange between the EESS and electric distribution grids independently, guaranteeing globally asymptotically convergence in the sense of Lyapunov via Hamiltonian formulation. Simulation results show the effectiveness and robustness of the generalized IDA-PBC to operate EESS as active and reactive power compensator in order to improve operative conditions in power distribution grids under balanced and unbalanced conditions.

A Perceptive Approach to Digital Image Watermarking Using a Brightness Model and the Hermite Transform
Mathematical Problems in Engineering
https://doi.org/10.1155/2018/5463632
Boris Escalante Ramírez¹ , Sandra Luz Gómez Coronel²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas

Keywords:
Abstract: This work presents a watermarking technique in digital images using a brightness model and the Hermite Transform (HT). The HT is an image representation model that incorporates important properties of the Human Vision System (HVS), such as the analysis of local orientation, and the model of Gaussian derivatives of early vision. The proposed watermarking scheme is based on a perceptive model that takes advantage of the masking characteristics of the HVS, thus allowing the generation of a watermark that cannot be detected by a human observer. The mask is constructed using a brightness model that exploits the limited sensibility of the human visual system for noise detection in areas of high or low brightness. Experimental results show the imperceptibility of the watermark and the fact that the proposed algorithm is robust to most common processing attacks. For the case of geometric distortions, an image normalization stage is carried out prior to the watermarking.

Comparative neutronic study of homogeneous and heterogeneous thorium fuel based core design in a lead-cooled fast reactor
Annals of Nuclear Energy
https://doi.org/10.1016/j.anucene.2017.12.022
Luis Carlos Juárez Martínez¹ , Juan Luis François Lacouture²
¹ Universidad Nacional Autónoma de México, Instituto de Energías Renovables
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Lead cooled fast reactor, Adiabatic reactor, Nuclear core design, Thorium, SERPENT
Abstract: In the present work the utilization of thorium is investigated in a lead-cooled fast reactor. Two thorium fuel strategies were analyzed: a homogeneous and a heterogeneous mixture of 232Th were set in the European Lead-cooled Fast Reactor core model. For this, the Monte Carlo Serpent-2.27 code and the JEFF-3.1 cross section library were used to perform the calculations. Three neutronic parameters were analyzed for each fuel strategy: the effective neutron multiplication factor (keff) for a cycle of 900 days, the Doppler constant and the reactivity effect of coolant density. With the homogeneous mixture of 232Th the neutron multiplication factor increases during the whole operating cycle (900 days), allowing a longer fuel cycle, keeping negative values for the Doppler constant and the reactivity effect of coolant density, with -692 pcm and -148 pcm, respectively. On the other hand, the addition of 232Th heterogeneously in the core showed that there is the necessity to have a reactivity excess around 2.2% Δk to fulfill the same fuel operating cycle. Even when there is a ThO2 blanket zone, the 233U production is not enough to increase the keff value and to enlarge the fuel operating cycle. Otherwise, the Doppler constant and the reactivity effect of coolant density are also negative values.

Contracting angular velocity observer for small satellites
IEEE Transactions on Aerospace and Electronic Systems
https://doi.org/10.1109/TAES.2018.2829360
Rafael Chávez Moreno¹ , Yu Tang Xu¹ , Juan Carlos Hernández ¹ , Haibo Ji ²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² University of Science and Technology of China, Automatic Control Department

Keywords: Observers, Trajectory, Attitude control, Angular velocity, Noise measurement, Synchronization, Convergence
Abstract: This paper addresses the problem of estimating the angular velocity given noisy attitude measurements for attitude control in small satellites. Based on contraction analysis, a set of global exponentially convergent observers, namely, reduced-order, complete-order, and synchronized observers is designed. Simulations and experimental results are presented to illustrate their performance.

Design of a Hypoxia Device Detector with Wireless Alert
International Journal of Engineering Science and Research Technology
https://doi.org/10.5281/zenodo.1207055
Teo Cortés ¹ , Fátima Moumtadi ¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: SPO2, oxygen saturation, oxyhemoglobin, deoxyhemoglobin, pulse oximeter
Abstract: In the present work, the development of a non-invasive pulse oximeter is proposed, which will send a warning message in possible case of hypoxia. The oximeter will generate a red light and an infrared light, both lights will be reflected on the skin and captured by a photodiode, that signal will be processed in a microcontroller for calculating the oxygen saturation in the blood (SPO2). That will happen by making a comparative between the light absorbed by oxyhemoglobin and deoxyhemoglobin. In such a way that if SPO2 is below the normal medical parameters, the device will be able to send an alert to another similar device by wireless communication. This device has been proposed to be used by people with cardiopulmonary problems, people who are under anesthesia, as well as people who work in places at high altitudes, such as mountain climbers.

On the maximum operating frequency of prosthetic heart valves
Biomedical Physics & Engineering Express
https://doi.org/10.1088/2057-1976/aacc2e
Carlos Alberto Palacios Morales¹ , José Enrique Guzmán Vázquez² , A. Beltrán ³ , Leopoldo Ruiz Huerta⁴ , A. Caballero Ruiz⁴ , Roberto Zenit ³
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería
³ Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
⁴ Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología

Keywords: prosthesis, heart valves, accelerated testing, mechanical limits
Abstract: A criterion is presented to evaluate the maximum pulsating flow frequency beyond which prosthetic heart valves cease to properly operate. The idea is tested with the experimental measurements obtained with an biological Edwards-Carpenter valve type model. It is found that beyond a certain characteristic frequency, the valve is no longer capable of fully operating in a cyclic manner. Furthermore, based on data recently reported by other authors, this preliminary comparison suggests that for a wide range of materials, leaflet sizes and operating conditions prosthetic heart valves might fail to properly operate for frequencies beyond 4.5 Hz (or 240 ppm).

Pulsatile electroosmotic flow of a Maxwell fluid in a parallel flat plate microchannel with asymmetric zeta potentials
Applied Mathematics and Mechanics
https://doi.org/10.1007/s10483-018-2328-6
M. Peralta ¹ , Oscar Eladio Bautista Godínez¹ , Federico Méndez Lavielle² , Eric Gustavo Bautista Godínez¹
¹ Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: pulsatile electroosmotic flow (PEOF), flat plate microchannel, asymmetric zeta potential, Maxwell fluid
Abstract: The pulsatile electroosmotic flow (PEOF) of a Maxwell fluid in a parallel flat plate microchannel with asymmetric wall zeta potentials is theoretically analyzed. By combining the linear Maxwell viscoelastic model, the Cauchy equation, and the electric field solution obtained from the linearized Poisson-Boltzmann equation, a hyperbolic partial differential equation is obtained to derive the flow field. The PEOF is controlled by the angular Reynolds number, the ratio of the zeta potentials of the microchannel walls, the electrokinetic parameter, and the elasticity number. The main results obtained from this analysis show strong oscillations in the velocity profiles when the values of the elasticity number and the angular Reynolds number increase due to the competition among the elastic, viscous, inertial, and electric forces in the flow.

Validated artificial neural networks in determining petrophysical properties: A Case study from Colombia
Interpretation
https://doi.org/10.1190/INT-2018-0011.1
Ursula Iturrarán Viveros¹ , Andrés M. Muñoz García² , Jorge O. Parra ³ , Josué Tago Pacheco⁴
¹ Universidad Nacional Autónoma de México, Facultad de Ciencias
² Instituto Tecnológico Metropolitano de Medellín,
³ JPGeosciences,
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: attributes, neural networks, clastic, facies, layered
Abstract: We have applied instantaneous seismic attributes to a stacked P-wave reflected seismic section in the Tenerife field located in the Middle Magdalena Valley Basin in Colombia to estimate the volume of clay Vclay and the density ? at seismic scale. The well logs and the seismic attributes associated to the seismic trace closer to one of the available wells (Tenerife-2) is the information used to train some multilayered artificial neural networks (ANN). We perform data analysis via the gamma test, a mathematically nonparametric nonlinear smooth modeling tool, to choose the best input combination of seismic attributes to train ANNs to estimate Vclay and ?. Once the ANNs are trained, they are applied to predict these parameters along the seismic line. From the continuous estimations of Vclay, we distinguish two facies: sands for Vclay<0.5 and shales when Vclay=0.5. These estimations confirm the production of the Mugrosa C-Sands zone, and we draw the brown shale that correlates with the high-amplitude attributes and the yellow sand that correlates with the low-amplitude attributes. Using the well-log information for VP and the facies classification (also in the well log), two cubic polynomials that depend on time (or depth) are obtained, one for sands and the other for shales, to fit the VP. These two cubic polynomials and the facies classification obtained from the Vclay at the seismic scale enable us to estimate VP at the seismic scale. To validate the 2D VP and ? predicted data, a forward-modeling software (the Kennett reflectivity algorithm) is used. This model calculates synthetic seismograms that are compared with the real seismograms. This comparison indicates a small misfit that suggests that the VP and ? images are representing the reservoir description characteristics and the ANN method is accurate to map these parameters.

A B-Spline Framework for Smooth Derivative Computation in Well Test Analysis Using Diagnostic Plots
Groundwater
https://doi.org/10.1111/gwat.12579
Josué Tago Pacheco¹ , Antonio Hernández Espriú¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: In the oil and gas industry, well test analysis using derivative plots, has been the core technique in examining reservoir and well behavior over the last three decades. Recently, diagnostics plots have gained recognition in the field of hydrogeology; however, this tool is still underused by groundwater professionals. The foremost drawback is that the derivative function must be computed from noisy field measurements, usually based on finite-difference schemes, which complicates the analysis. We propose a B-spline framework for smooth derivative computation, referred to as Constrained Quartic B-Splines with Free Knots. The approach presents the following novelties in relation to methodological precedents: (1) the use of automatic equality derivative constraints, (2) a knot removal strategy and (3) the introduction of a Boolean shape parameter that defines the number of initial knots to choose. These can lead to evaluate both simple (manually recorded drawdown measurements) and complex (transducer measured records) datasets. Furthermore, we propose an additional shape preserving smoothing preprocess procedure, as a simple, fast and robust method to deal with extremely noisy signals. Our framework was tested in four pumping tests by comparing the spline derivative with regards to the Bourdet algorithm, and we found that the latter is rather noisy (even for large differentiation intervals) and the second derivative response is basically unreadable. In contrast, the spline first and second derivative led to smoother responses, which are more suitable for interpretation. We concluded that the proposed framework is a welcome contribution to evaluate reliable aquifer tests using derivative-diagnostic plots.

Adaptation of Levant's Differentiator Based, on Barrier Function
International Journal of Control
https://doi.org/10.1080/00207179.2017.1406149
Hussein Obeid ¹ , Leonid Fridman Golredich² , Salah Laghrouche ¹ , Mohamed Harmouche ³ , Mohammad Ali Golkani ⁴
¹ Universite Bourgogne Franche-Comté/UTBM,,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Université Paris Saclay, Laboratoire des signaux et systemes
⁴ Graz University of Technology, Institute of Automation and Control

Keywords: Levant's differentiator, sliding-mode control, adaptive control
Abstract: An algorithm for adaptation of Levant's differentiator (LD) gains is designed for the case when the upper bound of second derivative of base signal exists but it is unknown. The barrier function is employed in this algorithm in order to adapt both gains of LD. Thanks to its feature, from the initial time moment it can be guaranteed that the error of estimation of signal belongs to a predefined vicinity of zero. Moreover, the proposed barrier algorithm can ensure the convergence of LD to some vicinity of the first derivative. This barrier adaptation enjoys two main advantages: it ensures a fast convergence and could indicate that LD does not converge in the case of noisy signal.

An Evolutive Linear Kinematic Source Inversion
Journal of Geophysical Research: Solid Earth
https://doi.org/10.1029/2017JB015388
Hugo Sánchez Reyes¹ , Josué Tago Pacheco² , Ludovic Métivier ¹ , Víctor M. Cruz Atienza³ , Jean Virieux ¹
¹ Universite Grenoble Alpes, Institut des Sciences de la Terre
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Universidad Nacional Autónoma de México, Instituto de Geofísica

Keywords: linear inverse formulation, kinematic source inversion, hierarchical evolutive model parametrization, source inversion validation, Kumamoto earthquake
Abstract: We present a new hierarchical time kinematic source inversion method able to assimilate data traces through evolutive time windows. A linear time domain formulation relates the slip rate function and seismograms, preserving the positivity of this function and the causality when spanning the model space: taking benefit of the time-space sparsity of the rupture model evolution is as essential as considering the causality between rupture and each record delayed by the known propagator operator different for each station. This progressive approach, both on the data space and on the model space, does require mild assumptions on prior slip rate functions or preconditioning strategies on the slip rate local gradient estimations. These assumptions are based on simple physical expected rupture models we foresee. Successful applications of this method to a well-known benchmark (Source Inversion Validation Exercise 1) and to the recorded data of the 2016 Kumamoto mainshock (Mw=7.0) illustrate the advantages of this alternative approach of a linear kinematic source inversion. This stabilized overparameterized optimization of a linear forward problem has a potential extension to stochastic inversion in a Bayesian framework in the future to assess uncertainties on kinematic source inversions, which is more difficult to investigate under nonlinear formulations.

Dispersion coefficient in an electro-osmotic flow of a viscoelastic fluid through a microchannel with a slowly varying wall zeta potential
Journal of Fluid Mechanics
https://doi.org/10.1017/jfm.2018.11
José Carlos Arcos Hernández¹ , Federico Méndez Lavielle² , Eric Gustavo Bautista Godínez¹ , Oscar Eladio Bautista Godínez¹
¹ Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: low-Reynolds-number flows, lubrication theory, micro-/nano-fluid dynamics
Abstract: The dispersion coefficient of a passive solute in a steady-state pure electro-osmotic flow (EOF) of a viscoelastic liquid, whose rheological behaviour follows the simplified Phan-Thien–Tanner (sPTT) model, along a parallel flat plate microchannel, is studied. The walls of the microchannel are assumed to have modulated and low ?? potentials, which vary slowly in the axial direction in a sinusoidal manner. The flow field required to obtain the dispersion coefficient was solved using the lubrication approximation theory (LAT). The solution of the electric potential is based on the Debye–Hückel approximation for a symmetric electrolyte. The viscoelasticity of the fluid is observed to notably amplify the axial distribution of the effective dispersion coefficients due to the variation in the ?? potentials of the walls. The problem was formulated for two cases: when the Debye layer thickness (EDL) was on the order of unity (thick EDL) and in the limit where the thickness of the EDL was very small compared with the height of the microchannel (thin EDL limit). Due to the coupling between the nonlinear governing equations and the sPTT fluid model, they were replaced by their approximate linearized forms and solved in the limit of ?? using the regular perturbation technique. Here ?? is the amplitude of the sinusoidal function of the ?? potentials. Additionally, the numerical solution of the simplified governing equations was also obtained for ?? and compared with the approximate solution, showing excellent agreement for ?? . Note that the dispersion coefficient primarily depends on the Deborah number, on the ratio of the half-height of the microchannel to the Debye length, and on the assumed variation in the ?? potentials of the walls.

DSPWM multilevel technique of 27-levels based on FPGA for the cascaded DC/AC power converter operation
International Transactions on Electrical Energy Systems
https://doi.org/10.1002/etep.2479
Nadia María Salgado Herrera¹ , J. Aurelio Medina Ríos¹ , Roberto Tapia Sánchez¹ , Olimpo Anaya Lara¹ , Juan Ramón Rodríguez Rodríguez²
¹ Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Eléctrica
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: cascaded DC/AC converters, DSPWM, FPGA, multilevel H-bridges
Abstract: In this paper, a digital sinusoidal pulse width modulation (DSPWM) multilevel technique of 27-levels based on field programmable gate array (FPGA) is introduced, as an alternative to control of the direct current/alternating current multilevel power converters. The implementation of this technique with an FPGA XC3S500E model is achieved in the Xilinx Spartan-3E FPGA platforms. An experimental prototype is implemented by 3-cascaded H-bridges controlled by the DSPWM multilevel technique, generating high efficiency, low cost, and lower harmonic content. The efficiency of the DSPWM multilevel technique using R, RL, RC, and RLC loads connected to the power network is verified.

Flow and air conditioning simulations of computer turbinectomized nose models
Medical & biological engineering & computing
https://doi.org/10.1007/s11517-018-1823-2
José Eduardo Pérez Mota¹ , Francisco Javier Solorio Ordaz¹ , Jaime Gonzalo Cervantes De Gortari¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Unsteady nasal airflow, computer partial turbinectomy, nasal surgery simulation
Abstract: Air conditioning for the human respiratory system is the most important function of the nose. When obstruction occurs in the nasal airway, turbinectomy is used to correct such pathology. However, mucosal atrophy may occur sometime after this surgery when it is overdone. There is not enough information about long-term recovery of nasal air conditioning performance after partial or total surgery. The purpose of this research was to assess if, based on the flow and temperature/humidity characteristics of the air intake to the choana, partial resection of turbinates is better than total resection. A normal nasal cavity geometry was digitized from tomographic scans and a model was printed in 3D. Dynamic (sinusoidal) laboratory tests and computer simulations of airflow were conducted with full agreement between numerical and experimental results. Computational adaptations were subsequently performed to represent six turbinectomy variations and a swollen nasal cavity case. Streamlines along the nasal cavity and temperature and humidity distributions at the choana indicated that the middle turbinate partial resection is the best alternative. These findings may facilitate the diagnosis of nasal obstruction and can be useful both to plan a turbinectomy and to reduce postoperative discomfort.

Learning-based frequency response function estimation for nonlinear systems
International Journal of Systems Science
https://doi.org/10.1080/00207721.2018.1498555
Suresh Thenozhi ¹ , Yu Tang Xu²
¹ Universidad Autónoma de Querétaro,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Neural network, nonlinear frequency response, non-parametric modelling, RBF, support vector machines
Abstract: In this paper, we perform the nonlinear frequency response function (FRF) estimation for a class of nonlinear systems. Two non-parametric estimation techniques are considered: radial basis function neural network (RBF-NN)-based estimation and support vector machine (SVM)-based estimation. Based on the system's available observations, the proposed estimation models are used to predict its frequency response. Simulation results are provided to demonstrate the model implementation. Finally, a comparative study is carried out to evaluate the effectiveness of the RBF-NN and SVM schemes, which has demonstrated that the SVM outperformed RBF-NN in the FRF estimation.

Sistema de registro y monitoreo cardíaco a distancia para embrión de gallina
Journal de Ciencia e Ingeniería
https://jci.uniautonoma.edu.co/2018/2018-1.pdf
Fátima Moumtadi ¹ , Alexis Robles Becerra¹ , Ángel Lambertt Lobaina²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Anáhuac, Facultad de Ingeniería

Keywords: Sensor, monitor cardíaco, embrión de gallina, base de datos.
Abstract: Debido al constante desarrollo de los métodos utilizados en la incubación además del aumento en el volumen de producción de aves de corral y pruebas realizadas a embriones de pollo, es necesario monitorear los embriones correspondientes a un lote de huevos seleccionados para su inspección. Uno de los parámetros de interés es la actividad cardíaca. Diversos trabajos se han realizado utilizando algunos métodos como el balistocardiograma que se basa en detectar los movimientos del embrión por acción del bombeo de la sangre o el acustocardiograma, que mediante el cambio de presión producido entre el interior del huevo y el exterior se pueden obtener datos de la actividad cardíaca. Para monitorear la actividad cardíaca, se diseñó e implementó un prototipo no invasivo que se encarga de la adquisición de la señal cardíaca por medio de emisor y receptor infrarrojo, la señal es acondicionada y procesada para posteriormente ser guardados en una base de datos y mostrados en una página web.

A multiphase active contour model based on the Hermite transform for texture segmentation
Optics, Photonics, and Digital Technologies for Imaging Applications V
https://doi.org/10.1117/12.2306541
Erik Carbajal Degante¹ , Jimena Olveres ² , Boris Escalante Ramírez¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas

Keywords: human visual system, hermite transform
Abstract: Texture is one of the most important elements used by the human visual system (HVS) to distinguish different objects in a scene. Early bio-inspired methods for texture segmentation involve partitioning an image into distinct regions by setting a criterion based on their frequency response and local properties in order to further perform a grouping task. Nevertheless, the correct texture delimitation still remains as an important challenge in image segmentation. The aim of this study is to generate a novel approach to discriminate different textures by comparing internal and external image content in a set of evolving curves. We propose a multiphase formulation with an active contour model applied on the highest energy coefficients generated by the Hermite transform (HT). Local texture features such as scale and orientation are reflected in the HT coefficients which guide the evolution of each curve. This process leads to the enclosure of similar characteristics in a region associated with a level set function. The efficiency of our proposal is evaluated using a variety of synthetic images and real textured scenes.

A Novel Method to Estimate the Reaching Time of the Super-Twisting Algorithm
IEEE Transactions on Automatic Control
https://doi.org/10.1109/TAC.2018.2812789
Richard Seeber ¹ , Martin Horn ¹ , Leonid Fridman Golredich²
¹ Graz University of Techonology, Institute of Automation and Control
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Perturbation methods, Eigenvalues and eigenfunctions, Sliding mode control, Estimation, Lyapunov methods, Upper bound, Electronic mail
Abstract: The super-twisting algorithm is a well-known technique in the field of sliding mode control or observation. In this contribution, an exact analytic expression for this algorithm's finite reaching time in the unperturbed case is derived. Based on this derivation, a novel estimation for the upper bound of the algorithm's reaching time the presence of perturbations is presented. The considered perturbations may be composed of additive components that are either Lipschitz continuous in time or Hölder continuous in the sliding variable. Both analytically and in the course of numerical examples the new strategy is shown to yield significant improvements compared to existing reaching time estimates.

A Simple Spectral Observer
Mathematical and Computational Applications
https://doi.org/10.3390/mca23020023
Lizeth Torres Ortiz¹ , Javier Jiménez Cabas² , José Francisco Gómez Aguilar³ , Pablo Pérez Alcaraz⁴
¹ Universidad Nacional Autónoma de México, Instituto de Ingeniería
² Universidad de la Costa, Departamento de Ciencias de la Informática y Electrónica
³ Tecnológico Nacional de México, Centro Nacional de Investigación y Desarrollo Tecnológico
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: signal processing, Fourier series, state observer, Short Time Fourier Transform, time-frequency analysis
Abstract: The principal aim of a spectral observer is twofold: the reconstruction of a signal of time via state estimation and the decomposition of such a signal into the frequencies that make it up. A spectral observer can be catalogued as an online algorithm for time-frequency analysis because is a method that can compute on the fly the Fourier Transform (FT) of a signal, without having the entire signal available from the start. In this regard, this paper presents a novel spectral observer with an adjustable constant gain for reconstructing a given signal by means of the recursive identification of the coefficients of a Fourier series. The reconstruction or estimation of a signal in the context of this work means to find the coefficients of a linear combination of sines a cosines that fits a signal such that it can be reproduced. The design procedure of the spectral observer is presented along with the following applications: (1) the reconstruction of a simple periodical signal, (2) the approximation of both a square and a triangular signal, (3) the edge detection in signals by using the Fourier coefficients, (4) the fitting of the historical Bitcoin market data from 1 December 2014 to 8 January 2018 and (5) the estimation of a input force acting upon a Duffing oscillator. To round out this paper, we present a detailed discussion about the results of the applications as well as a comparative analysis of the proposed spectral observer vis-à-vis the Short Time Fourier Transform (STFT), which is a well-known method for time-frequency analysis.

Acid drainage neutralization and trace metals removal by a two-step system with carbonated rocks, Estado de Mexico, Mexico
Environmental Earth Sciences
https://doi.org/10.1007/s12665-018-7248-2
José Enrique Santos Jallath¹ , Francisco Martín Romero² , Rosario Iturbe Argüelles³ , Angélica Cervantes Macedo¹ , Juan Goslinga Arenas¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Geología
³ Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Acid drainage treatment, Limestone and phyllite rock, Trace metals adsorption, Phyllosilicates alteration, Fe and Al precipitation
Abstract: The following study is carried out in a mine of Mexico where acid drainage is produced. At the site, two types of rock which contain calcite are present, graphitic phyllite and limestone, and their use is proposed in a treatment system. Acid drainage contains dissolved Al, Cd, Cu, Fe, Mn and Zn, as well as high concentration of sulphates. By means of shaking tests conducted using flasks, the efficiency of the proposed two-step treatment was evaluated, first using phyllite to remove Fe and Al and then limestone to remove Cu, Cd, Mn and Zn. During the tests performed using phyllite, a pH = 6.00–6.16 was reached, and 100% of Al, Fe and Cu was removed. During the second step, using limestone, a pH = 7.77–8.39 was achieved and 100% of Cd, 95–99% of Zn and 74–89% of Mn were removed. Sediment characterization indicates that Al and Fe precipitate as hydroxysulphates, Cu removal mainly occurs by sorption in iron hydroxysulphates, while Cd, Mn and Zn are mostly removed by adsorption in clay phases formed by alteration of phyllosilicates contained in rock.

Effects of concentrated solar irradiation on allotropic transformations of AISI 316 stainless steel
Revista de Metalurgia
https://doi.org/10.3989/revmetalm.133
Omar Álvarez ¹ , Armando Rojas ² , Arturo Barba Pingarrón² , Camilo A. Arancibia ¹ , Jorge Álvarez ³ , Dulce V. Melo ⁴ , Carlos E. Arreola ¹
¹ Universidad Nacional Autónoma de México, Instituto de Energías Renovables
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Instituto Tecnológico y de Estudios Superiores de Monterrey, Departamento de Ingeniería y Arquitectura
⁴ Instituto Tecnológico y de Estudios Superiores de Monterrey, Departamento de Mecatrónica

Keywords: Acero inoxidable, Austenítico, Ferrita-Δ obtenida, Irradiación solar concentrada, Transformaciones alotrópicas
Abstract: Se investiga la transformación de fases que pueden ocurrir en un acero austenítico (AISI 316) mediante la demostración de la aparición de ferrita-Δ que se obtiene en ciclos iniciales de calentamiento usando irradiación solar concentrada (ISC) a magnitudes necesitadas para obtener temperaturas de operación de sistemas de tipo torre central. Cuatro especímenes de acero inoxidable AISI 316 cortados de una misma pieza, fueron expuestos a ISC en el Horno Solar de Alto Flujo Radiativo de la Universidad Nacional Autónoma de México para desarrollar el ciclado térmico. El acero AISI 316 fue seleccionado por ser reportado entre los materiales más baratos usado en receptores de ISC. Pruebas de resistencia a la tensión monotónica demostraron que no existe un efecto relevante del ciclado térmico en las propiedades mecánicas resultantes. Las transformaciones de fase fueron caracterizadas usando microscopía óptica, difracción de rayos X, y microscopía electrónica de barrido con espectroscopía de dispersión de energía de rayos X. La aparición de la fase de ferrita-Δ fue la principal diferencia entre los especímenes tratados con ISC y dos especímenes de referencia. La fracción UV de la ISC demostró tener el potencial de lograr estas transformaciones de fase a una temperatura cercana a los 630 °C.

Output-Feedback Variable Gain Super-Twisting Algorithm for Arbitrary Relative Degree Systems
International Journal of Control
https://doi.org/10.1080/00207179.2017.1401230
Tiago Roux Oliveira¹ , Víctor Hugo Pereira Rodrigues¹ , Antonio Estrada ² , Leonid Fridman Golredich³
¹ State University of Rio de Janeiro, Department of Electronics and Telecommunication Engineering
² Center for Engineering and Industrial Development,
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Uncertain nonlinear systems, variable structure systems, higher order sliding-mode control, exact differentiators, output feedback, global/semi-global stability
Abstract: This paper presents an output-feedback control strategy based on the variable gain super-twisting algorithm. The proposal achieves robust global/semi-global exact tracking results for plants with arbitrary relative degree. This is ensured in spite of parametric uncertainties and disturbances that may be state-dependent and time-varying. The construction of such controller is based on a (non)homogeneous higher order sliding-mode differentiator with dynamic gains. The gain adaptation schemes for the controller and differentiator are based on norm observers to overcome the lack of state measurement. The continuous nature of the obtained control signal alleviates the chattering phenomenon. The stability properties of the proposed controller are demonstrated by means of a Lyapunov function-based analysis. The theoretical results are verified through a simulation example, and experimentally tested on a seesaw module.

Special Issue on Differentiators
International Journal of Control
https://doi.org/10.1080/00207179.2018.1487580
Markus Reichhartinger ¹ , Denis Efimov ² , Leonid Fridman Golredich³
¹ Graz University of Technology, Institute of Automation and Control
² Villenueve d'Ascq, Nord Europe Center
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: Real-time differentation is an old and important problem with a variety of control applications. Examplarily consider the design of output-feedback controllers. Therein differentiators are often used to obtain additional system information. Proportional-Derivative controllers may be regarded as a very special case of this application.

Analysis of surface waves recorded at a mass movement in Brasilia, Brazil: An implication in hazard mitigation
Geociências
https://www.revistageociencias.com.br/geociencias-arquivos/37/volume37_2.html
Yawar Hussain ¹ , Hernán Martínez Carbajal² , Martín Cárdenas Soto³ , Rogério Elias Uagoda Soares⁴
¹ University of Brasilia, Department of Civil and Environmental Engineering
² Universidad Nacional de Colombia, Facultad de Minas
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁴ University of Brasilia, Department of Geography

Keywords: HVSR, MASW, SPD, Noise Interferometry, Empirical Green Function
Abstract: Ever increasing urbanization over the thick and less cohesive soil of the Federal District (DF) – Brazil, has increased area's vulnerability to natural hazards, especially the soil erosion and mass movement. This preliminarily study applied noise based geophysical techniques like power spectral density (PSD), horizontal to vertical spectral ratio (HVSR), multichannel analysis of surface waves (MASW) and noise interferometry to a mass movement in Brasilia for the understating of geodynamic processes working in the background of these hazards. Here obtained results show a uniform stratigraphic peak at 2 Hz observed on all HVSR curves, a four layered shear wave section was obtained by MASW. Dispersion curve (frequency vs phase velocity) shows first and second fundamental modes at frequencies of 5 and 25 Hz, respectively. Noise correlograms show time delay larger than +- 0.5 sec on the waveforms of ZR (vertical-radial) component, mainly in acausal part. Relative velocity changes calculated by stretching technique show anomalous trends in response to rainfall events. Follow research will focus on the detection of possible changes in noise records within mass movement mainly related to natural triggering factors (rainfall and river erosion) under more controlled data conditions.

Efficient method for the real-time contingency analysis of meshed HVDC power grids fed by VSC stations
IET Generation, Transmission and Distribution
https://doi.org/10.1049/iet-gtd.2017.1104
Luis Miguel Castro González¹ , Enrique Acha Daza² , Juan Ramón Rodríguez Rodríguez¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Tampere University of Technology, Department of Electrical Engineering

Keywords: HVDC power convertors, HVDC power transmission, power grids
Abstract: An efficient method for the real-time contingency analysis of meshed high-voltage direct current (HVDC) power grids fed by voltage source converter (VSC) stations is introduced here. A linearised AC/DC grid model is initially determined considering the control strategies of the various VSC units. This lays the foundations for the determination of linear sensitivity factors with which the contingency analysis is carried out to evaluate the real-time N -1 criterion in AC/DC grids, as demanded by system control centres. Distribution and power-injection factors are subsequently derived for efficiently assessing the impact of AC/DC transmission line outages and load/generator disconnections on the HVDC grid. Conversion factors are also derived to estimate the impact of the loss of VSC stations on the AC/DC network, this being another inherent contribution of this work. The efficiency and validity of this timely approach, which finds practical applicability to the real-time operation of HVDC power grids, is confirmed using a meshed DC network fed by three VSC stations. The disconnection of AC and DC transmission lines, generators, and VSC stations are dynamically simulated using Simulink and their post-disturbance steady-state conditions are compared against those computed by the introduced method where it is confirmed that both solutions concur very well with each other.

Enhancement in Curie Temperature in Ytrium Iron Garnet by doping with Neodymium
Materials
https://doi.org/10.3390/ma11091652
Esperanza Baños López¹ , Félix Sánchez De Jesús¹ , Claudia Alicia Cortés Escobedo² , Arturo Barba Pingarrón³ , Ana María Bolarín Miró¹
¹ Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
² Instituto Politécnico Nacional, Centro de Investigación e Innovación Tecnológica
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: NdxY3-xFe5O12, rare earth doped YIG, yttrium iron garnet, Y3Fe5O12, Curie temperature
Abstract: The effect of the substitution of Y3+ by Nd3+ on the structural and magnetic properties of neodymium-doped yttrium iron garnet, NdxY3-xFe5O12 with x in the range of 0–2.5, is presented. Oxide powders of Fe2O3, Nd2O3, and Y2O3 were mixed in a stoichiometric ratio and milled for 5 h using high-energy ball milling, before being uniaxially pressed at 900 MPa and annealed at 1373 K for 2 h to obtain NdxY3-xFe5O12 (0 = x = 2.5). It was found that the mechanical milling of oxides followed by annealing promotes the complete structural formation of the garnet structure. Additionally, the X-ray diffraction patterns confirm the complete introduction of Nd3+ into the garnet structure with a neodymium doping concentration (x) of 0–2.0, which causes a consistent increment in the lattice parameters with the Nd3+ content. When x is higher than 2.0, the yttrium orthoferrite is the predominant phase. Besides, the magnetic results reveal an increase in the Curie temperature (583 K) as the amount of Nd3+ increases, while there was enhanced saturation magnetization as well as modified remanence and coercivity with respect to non-doped YIG.

Experiences and Proposals for the Application of Concentrated Solar Energy in the Processing of Materials
Modern Environmental Science and Engineering
https://doi.org/10.15341/mese(2333-2581)/06.04.2018/008
Omar Álvarez Brito¹ , Arturo Barba Pingarrón² , Armando Rojas ² , Alfonso Vázquez ³ , Gloria Rodríguez ⁴ , Raúl Valdéz Navarro²
¹ Universidad Nacional Autónoma de México, Instituto de Energías Renovables
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Consejo Superior de Investigaciones Científicas, Centro Nacional de Investigaciones Metalúrgicas
⁴ Universidad de Castilla La Mancha, ETS Ingenieros Industriales

Keywords: solar energy assisted processes, low environmental impact manufacturing proposals
Abstract: Different experiences described are related to research works based on the application of concentrated solar energy (CSE). The experiences described are associated with quenching processes, layer generation processes by means of powder melting (cladding), self-propagated synthesis to obtain intermetallics, the formation of nitride layers of titanium in an atmosphere of Nitrogen, nitriding of steel and cast iron, the sintering of metals and ceramics, some processes of reduction of oxides and of welding, allotropy of metallic solid solutions; every one using CSE as the heat source. There are also experiences related to hybrid heat source processes such as electric induction and CSE hardening. At the end of the description, an evaluation of all these possibilities is carried out and proposals are issued on those that seem most promising and viable at this time. We believe that CSE has a very promising future as an important resource to be used in industrial processes according to the needs of a better environment, as a relevant way to reduce energy consumption taking advantage of the unique opportunities offered.

Identification of coherent trajectories by modal characteristics and hierarchical agglomerative clustering
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2017.12.029
Mario Roberto Arrieta Paternina¹ , Alejandro Zamora Méndez² , José Ortiz Bejar³ , Joe H. Chow ⁴ , Juan Manuel Ramírez Arredondo⁵
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
³ Universidad Michoacana de San Nicolás de Hidalgo,
⁴ Rensselaer Polytechnic Institute, Department of Electrical Computer and Systems Engineering
⁵ Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados

Keywords: Coherency, Hierarchical agglomerative clustering, Inter-area modes, Modal identification, Slow coherency
Abstract: This paper introduces a novel method to identify coherent generators using the inter-area modal characteristics of power systems. The key idea is to extract the inter-area modes from the simulated data and then to apply a clustering strategy. Thus, the proposed method consists of extracting the phase of the oscillatory modes via a modal identification technique and applying a hierarchical agglomerative clustering technique together with the Elbow's method to gather the phases of each mode, enabling to provide coherent trajectories of generators. The proposed method uses a Taylor-Fourier filtering strategy to remove noises and nonlinearity in the time evolution of coherent generators. Simulated signals with noise added are used for assessing the proposition. Results corroborate the proposed strategy for identifying coherent trajectories in large-scale power systems.

Detection of life threatening ventricular arrhythmia using digital taylor fourier transform
Frontiers in Physiology
https://doi.org/10.3389/fphys.2018.00722
Rajesh Kumar Tripathy ¹ , Alejandro Zamora Méndez² , José Antonio De la O Serna ³ , Mario Roberto Arrieta Paternina⁴ , Juan Gregorio Arrieta Paternina⁵ , Ganesh R. Naik ⁶
¹ Siksha 'O' Anusandhan Deemed to be University, Faculty of Engineering and Technology
² Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
³ Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁵ Sanatorio Güemes,
⁶ Western Sydney University, MARCS Institute

Keywords: life threatening arrhythmia, Taylor-Fourier transform, magnitude and phase features, LSSVM, radial basis function kernel, classifier performance
Abstract: Accurate detection and classification of life-threatening ventricular arrhythmia episodes such as ventricular fibrillation (VF) and rapid ventricular tachycardia (VT) from electrocardiogram (ECG) is a challenging problem for patient monitoring and defibrillation therapy. This paper introduces a novel method for detection and classification of life-threatening ventricular arrhythmia episodes. The ECG signal is decomposed into various oscillatory modes using digital Taylor-Fourier transform (DTFT). The magnitude feature and a novel phase feature namely the phase difference (PD) are evaluated from the mode Taylor-Fourier coefficients of ECG signal. The least square support vector machine (LS-SVM) classifier with linear and radial basis function (RBF) kernels is employed for detection and classification of VT vs. VF, non-shock vs. shock and VF vs. non-VF arrhythmia episodes. The accuracy, sensitivity, and specificity values obtained using the proposed method are 89.81, 86.38, and 93.97%, respectively for the classification of Non-VF and VF episodes. Comparison with the performance of the state-of-the-art features demonstrate the advantages of the proposition.

Temporal variations of nucleosides and nucleotides in rabbit milk
Nucleosides, Nucleotides and Nucleic Acids
https://doi.org/10.1080/15257770.2018.1494278
Erika Navarrete ¹ , Georgina Díaz ¹ , Rodrigo Montúfar Chaveznava² , Ivette Caldelas ¹
¹ Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomédicas
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Circadian rhythms, maternal cyclical cues, maternal milk, nucleoside and nucleotide profiles
Abstract: Nucleotides and nucleosides have a preeminent role in physiological and biochemical processes for newborns, the major source of these during early development is the breast milk. Different biomolecules exhibit daily fluctuations in maternal milk that could transfer temporal information that synchronize newborn circadian system. As a first approach, we characterized the diurnal profile of nucleotides and nucleosides contained in maternal milk of rabbits during the first week of lactation. It is possible that some nucleosides, such as adenosine, play a relevant role in setting up the emerging circadian rhythmicity, whereas uridine and guanosine could participate in the maintenance of rhythmicity.

Higher order sliding-mode observers with scaled dissipative stabilisers
International Journal of Control
https://doi.org/10.1080/00207179.2016.1269951
W. Alejandro Apaza Pérez¹ , Leonid Fridman Golredich¹ , Jaime Alberto Moreno Pérez²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Sliding-mode observer, dissipative observer, nonlinear systems
Abstract: This paper proposes a global theoretically exact finite-time convergent observer for a class of nonlinear systems, which are not necessarily bounded-input-bounded-state with respect to the unknown inputs. With this aim, a scaled dissipative stabiliser is suggested ensuring that the highest derivative of the output estimation error is independent from the stabiliser gains. After this, a higher order sliding-mode differentiator with the gains adjusted to the upper bound of the unknown inputs is applied achieving finite-time convergence.

Karst Detection Beneath the Pyramid of El Castillo, Chichen Itza, Mexico, by Non-Invasive ERT-3D Methods
Scientific Reports
https://doi.org/10.1038/s41598-018-33888-9
René E. Chávez Segura¹ , Andrés Tejero Andrade² , Gerardo Cifuentes Nava¹ , Denisse L. Argote Espino³ , Juan Esteban Hernández Quintero¹
¹ Universidad Nacional Autónoma de México, Instituto de Geofísica
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Instituto Nacional de Antropología e Historia, Dirección de Estudios Arqueológicos

Keywords: Engineering, Solid Earth sciences
Abstract: Currently, archaeologists perform excavations determined by previous geophysical studies to accurately establish the prospective targets and minimize site disturbance. Among others, one of the methods most widely employed is the Electrical Resistivity Tomography (ERT-2D, -3D). However, investigation of the subsoil of archaeological buildings is not possible to carry out with traditional geophysical methods, because the structure itself prevents it. Therefore, it is necessary to design non-invasive special arrays capable of characterizing the subsoil of such buildings, while preserving their historical context. Here we show how this procedure combined with sequences of resistivity observations at depth allowed us to detect a low resistivity body beneath the pyramid of El Castillo in Chichen Itza (Mexico). This feature may be associated with a cavity (karst) partially filled with sweet water. On the other hand, a natural cavity was discovered under El Osario pyramid (south of El Castillo), at the end of the 19th century. Therefore, this pyramid was also studied to validate the effectiveness of this methodology, obtaining outstanding results. This method provides an interesting procedure to investigate the subsoil of archaeological structures for unveiling evidences that allow specialists to understand the religious meaning of these temples.

Super Twisting Algorithm in presence of time and state dependent perturbations
International Journal of Control
https://doi.org/10.1080/00207179.2016.1269952
I. Castillo ¹ , Leonid Fridman Golredich¹ , Jaime Alberto Moreno Pérez²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Sliding modes, super-twisting algorithm
Abstract: In this paper, generalized Super-Twisting Algorithm is applied to a class of systems whose perturbation and uncertain control coefficient are time- and state-dependent. A non-smooth strict Lyapunov function is used to obtain the conditions for the global finite-time stability and to estimate the time of convergence.

Continuous sliding-mode control for singular systems
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.4094
Debbie Hernández ¹ , Leonid Fridman Golredich¹ , Mohammad Ali Golkani ²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Graz University of Technology, Institute of Automation and Control

Keywords: continuous sliding-mode control, higher-order sliding mode control, implicit systems, robustness, singular systems, uncertain singular systems
Abstract: Singular systems with matched Lipschitz perturbations and uncertainties are considered in this paper. Since continuous solutions of an impulse-free singular system require continuous input signals, a two-step continuous sliding-mode control strategy to compensate matched Lipschitz perturbations and uncertainties in singular systems is proposed. Our suggested methodology is tested in a singular representation of a DC motor pendulum of relative degree two. The performance of the proposed strategy is assessed by comparing the accuracy, in both cases, with and without considering small noise in the output, obtained through other continuous sliding-mode control, and reconstruction/compensation of perturbations and uncertainties techniques.

Crystal structure and magnetic properties of cerium-doped YIG: Effect of doping concentration and annealing temperature.
Journal of Alloys and Compounds
https://doi.org/10.1016/j.jallcom.2017.09.304
Esperanza Baños López¹ , Claudia Alicia Cortés Escobedo² , Félix Sánchez De Jesús¹ , Arturo Barba Pingarrón³ , Ana María Bolarín Miró¹
¹ Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
² Instituto Politécnico Nacional, Centro de Investigación e Innovación Tecnológica
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Ce doped YIG, CeO2-YIG, YIG magnetic properties, YIG crystal structure, Iron garnet, Mechanochemical processing
Abstract: We present a study of the effect of the substitution of Y3+ by Ce3+ on the crystal structure and magnetic properties of cerium-doped yttrium iron garnet (YIG), CexY3-xFe5O12 (0 = x = 0.5), which was synthesized using high-energy ball milling. In particular, we aimed to study the effect of the cerium concentration and the annealing temperature on the crystal structure and magnetic properties of the Ce-doped YIG. Fe2O3, Y2O3, and Ce2(CO3)3 were mixed in a stoichiometric ratio, milled for 5 h, and annealed at different temperatures, from 1000 to 1400 °C. The X-ray diffraction pattern confirmed the presence of CeO2 as a secondary phase, together with the formation of the YIG structure, at all studied temperatures and compositions. A complete solid solution of Ce3+ in the garnet structure was obtained for the samples annealed at 1400 °C. Increasing the Ce3+ content resulted in a consistent decrease in the saturation magnetization and a slight decrease in the coercivity, resulting from the insertion of Ce3+ into the YIG structure and the presence of CeO2 as a secondary phase.

Ground-Motion Simulation by the Empirical Green's Function Method with a Source Defined by Two Corner Frequencies and a Two-Stage Summation Scheme
Bulletin of the Seismological Society of America
https://doi.org/10.1785/0120170184
Mauro Niño Lázaro¹ , Gustavo Ayala ² , Mario Ordaz ²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: acceleration, aftershocks, earthquakes, epicenters, geologic hazards, Green function, ground motion, Mexico, Mexico City earthquake 1985, natural hazards, numerical analysis, peak ground acceleration
Abstract: This article presents a procedure that is meant for the generation of catalogs of synthetic inslab earthquake ground motions. The procedure is based on the Green’s function method, an empirical method that considers an improved two-stage summation scheme of the basic signals emitted by the source. The proposed procedure takes into account that rise time and the acceleration spectrum of a signal originated at a known source S(ω) is more precisely described by an empirical source spectrum characterized by two corner frequencies ωa and ωb than it would be by the usual method where it is described by a single corner frequency. For the formulation of the probability density function of the rupture time, delays of the N cells in which the source of the simulated signal are discretized, and the definition of the empirical source spectrum is implemented using the aforementioned summation scheme. It is assumed that the extended area of the source is concentrated at a point and that the rupture duration is defined in accordance with its size. To illustrate the application of this procedure, the simulation of synthetic records of three different earthquakes events for several sites in Mexico is carried out. The results are validated via a statistical comparison of the response and Fourier acceleration spectra of the synthetic ground motions with the actual spectra of the real earthquake records from the three events considered as targets. Also, a comparison of the response spectra for the SCT station located in the lakebed zone of Mexico City with the single-stage and the enhanced two-stage procedure is presented. The latter comparison shows that signals simulated with the proposed procedure reproduce the amplification effects in the 1.4–5 s range in their response spectra in a better manner; this is also observed on real records, such as the east–west (E-W) component, which was registered at the SCT station during the 19 September 1985 Michoácan earthquake.

In-depth analysis of the capacitive filtered half wave rectifier
Computer Applications in Engineering Education
https://doi.org/10.1002/cae.22071
Jaime Octavio Guerra Pulido¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: differential equations solutions, diode, numerical simulation, piecewise linear approximation, RC filter, Rectifiers
Abstract: Undergraduate textbooks of Electronics Engineering courses commonly present the half-wave rectifier using a simplistic approach based on the linearization of an exponential equation to calculate the voltages in the circuit. However, these equations only apply when the time constant of the circuit is much larger than the period of the input signal and those equations for the case in which this condition is not met, are not presented. Herein, the most common equations in the literature are resumed. Next, the circuit is analyzed using three models of the diode and, for each one, a set of equations has been obtained to calculate the voltages, currents and times of the circuit. To apply these equations, the discharging time of the capacitor must be calculated through the solution of a transcendental equation. Nowadays, the computational tools to make this task easily are common and this should not be a challenge anymore. Also, performing these analyses could improve the understanding of the students and their capability to analyze circuits with diodes. Two examples are proposed to compare the equations proposed with the numerical solutions and the equations found in literature. Errors between the results obtained with the equations and the numerical simulations are less than 1% for the ripple, average and RMS voltages and maximum and repetitive average currents when the constant-drop model is used. The RMS current had an error of 6% because the conduction time of the diode is larger than that expected because of the nonlinear behavior of the diode.

THD Reduction in Wind Energy System Using Type-4 Wind Turbine/PMSG Applying the Active Front-End Converter Parallel Operation
Energies
https://doi.org/10.3390/en11092458
Nadia Maria Salgado Herrera¹ , David Campos Gaona¹ , Olimpo Anaya Lara² , Aurelio Medina Rios³ , Roberto Tapia Sánchez³ , Juan Ramón Rodríguez Rodríguez⁴
¹ University of Strathclyde, Institute for Energy and Environment
² University Of Strathclyde , Institute for Energy and Environment
³ Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Eléctrica
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: active front-end converter, back-to-back converter, permanent magnet synchronous generator (PMSG), THD, type-4 wind turbine, wind energy system, Opal-RT Technologies®
Abstract: In this paper, the active front-end (AFE) converter topology for the total harmonic distortion (THD) reduction in a wind energy system (WES) is used. A higher THD results in serious pulsations in the wind turbine (WT) output power and several power losses at the WES. The AFE converter topology improves the capability, efficiency, and reliability in the energy conversion devices, by modifying a conventional back-to-back converter, from using a single voltage source converter (VSC) to use pVSC connected in parallel, the AFE converter is generated. The THD reduction is achieved by applying a different phase shift angle at the carrier of digital sinusoidal pulse width modulation (DSPWM) switching signals of each VSC. To verify the functionality of the proposed methodology, the WES simulation in Matlab-Simulink® (Matlab r2015b, Mathworks, Natick, MA, USA) is analyzed, and the experimental laboratory tests using the concept of rapid control prototyping (RCP) and the real-time simulator Opal-RT Technologies® (Montreal, QC, Canada) is achieved. The obtained results show a type-4 WT with a total output power of 6 MVA, generating a THD reduction up to 5.5 times of the total WES current output by Fourier series expansion.

Output Feedback Continuous Twisting Algorithm
Automatica
https://doi.org/10.1016/j.automatica.2018.06.049
Tonametl Sanchez ¹ , Jaime Moreno ¹ , Leonid Fridman Golredich²
¹ Universidad Nacional Autónoma de México, Instituto de Ingeniería
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Sliding mode control, Lyapunov function
Abstract: Two output feedback controllers based on the Continuous Twisting Algorithm are provided. In those controllers, the state observers are based on the first and the second order Robust Exact Differentiators. The stability of the closed loops is proven through input-to-state stability properties. In the case of the second order differentiator, the conservation of homogeneity allows the output feedback scheme to preserve the robustness and accuracy properties of the state feedback Continuous Twisting Algorithm. In the same case, a smooth homogeneous Lyapunov function is constructed for the closed loop. A separation principle in the design of the controller and the observers is established. A qualitative analysis of the performance of the controllers in the presence of noise in the measurement is carried out. One of the schemes is used for output feedback control of a class of nonlinear systems.

Theoretical analysis of non-linear Joule heating effects on an electroosmotic flow with patterned surface charges
Physics of Fluids
https://doi.org/10.1063/1.5051175
Salvador Sánchez ¹ , Gabriel Ascanio ¹ , Federico Méndez Lavielle² , Oscar Eladio Bautista Godínez³
¹ Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords:
Abstract: In this work, non-linear Joule heating effects induced on an electroosmotic flow with patterned surface charges driven inside of a slit microchannel are analyzed. Here, the movement of the fluid is controlled by placing electro-thermal forces, which are induced through an imposed longitudinal electric field, E0, and the wall electric potential generated by electrodes inserted along the surface of the microchannel wall. For this analysis, the physical properties of the fluid are included as known functions, which depend on the temperature. Therefore, in order to determine the flow, temperature, and electric potential fields together with their simultaneous interactions, the governing equations have to be solved in a coupled manner. For a strong Joule heating, the non-isothermal flow regime reveals that with the presence of thermal gradients, the local electro-thermal and viscous forces, F???? and F???v,?, are affected in a sensible manner, which results in changes in the flow pattern causing the interruption or intensification of recirculations along the microchannel. In parallel, increments of flow rate or pressure are observed due to electro-thermal interactions associated with the mentioned thermal dependence of the physical properties; here the corresponding effects induced in those regions where thermal gradients are located prevail. The present analytical formulation allows determining the local electro-thermal rotational moment, M?, which clearly reveals the fundamental importance of when thermal gradients interact with the electric and flow fields. Thus, the local electro-thermal rotational moment can be used to interpret alterations in the flow pattern linked to the temperature rise.

Timing of the Cenozoic basins of Southern Mexico and its relationship with the Pacific truncation process: Subduction erosion or detachment of the Chortís block
Journal of South American Earth Sciences
https://doi.org/10.1016/j.jsames.2018.01.007
Gilberto Silva Romo¹ , Claudia Cristina Mendoza Rosales¹ , Emiliano Campos Madrigal¹ , Yoalli Bianii Hernández Marmolejo¹ , Orestes Antonio De la Rosa Mora¹ , Alam Israel De la Torre González¹ , Carlos Bonifacio Serralde¹ , Nayelly López García¹ , Juan Iván Nápoles Valenzuela¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fault basin, Magmatic zircon, Margin truncation, Fault system, Strike slip fault
Abstract: In the central sector of the Sierra Madre del Sur in Southern Mexico, between approximately 36 and 16 Ma ago and in the west to east direction, a diachronic process of the formation of ~north-south trending fault-bounded basins occurred. No tectono-sedimentary event in the period between 25 and 20 Ma is recognized in the study region. A period during which subduction erosion truncated the continental crust of southern Mexico has been proposed. The chronology, geometry and style of the formation of the Eocene Miocene fault-bounded basins are more congruent with crustal truncation by the detachment of the Chortís block, thus bringing into question the crustal truncation hypothesis of the Southern Mexico margin. Between Taxco and Tehuacán, using seven new Laser Ablation- Inductively-coupled plasma mass spectrometry (LA-ICP-MS) U-Pb ages in magmatic zircons, we refine the stratigraphy of the Tepenene, Tehuitzingo, Atzumba and Tepelmeme basins. The analyzed basins present similar tectono-sedimentary evolutions as follows: Stage 1, depocenter formation and filling by clastic rocks accumulated as alluvial fans and Stage 2, lacustrine sedimentation characterized by calcareous and/or evaporite beds. Based on our results, we propose the following hypothesis: in Southern Mexico, during Eocene-Miocene times, the diachronic formation of fault-bounded basins with general north-south trend occurred within the framework of the convergence between the plates of North and South America, and once the Chortís block had slipped towards the east, the basins formed in the cortical crust were recently left behind. On the other hand, the beginning of the basins’ formation process related to left strike slip faults during Eocene-Oligocene times can be associated with the thermomechanical maturation cortical process that caused the brittle/ductile transition level in the continental crust to shallow.

Observer Design for the Synchronization of Bilateral Delayed Teleoperators
European Journal of Control
https://doi.org/10.1016/j.ejcon.2018.06.001
Marco Antonio Arteaga Pérez¹ , Marisol Morales ¹ , Mauro López ¹ , Emmanuel Nuño ²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad de Guadalajara, Centro Universitario de Ciencias Exactas e Ingeniería

Keywords: Bilateral teleoperators, Observer design, Time delays, Synchronization
Abstract: Bilateral teleoperators are widely used in several applications such as surgical robots and underwater vehicles. However, due to the long distance between the local and remote manipulators, time delay arises over the communication channel, so that neither exact tracking position nor perfect transparency can be achieved. In free movement, most control approaches are meant to guarantee consensus or to synchronize the local and the remote robots by inducing periodic position trajectories. In constrained motion, the human operator can only have some telepresence feeling but not perfect transparency. Furthermore, most algorithms are designed assuming that joint velocities are available, while sometimes this is not the case and it is desirable to estimate joint velocities through an observer. In this work, a novel teleoperation controller–observer scheme is introduced that does not make use of velocity measurements and, more importantly, does not require the exact knowledge of the dynamical model. This scheme has the following properties: (a) in free motion and without a human operator, the local and the remote manipulators tend either to a periodic trajectory or to a particular position, thus achieving either synchronization or position consensus; (b) when a human operator moves the local robot, the remote manipulator tracks the commanded position with the corresponding delay; (c) in constrained motion, the human operator has some feeling of telepresence. Experimental results are provided to validate the proposed algorithm.

Role of the substrate on the growth of silicon quantum dots embedded in silicon nitride thin films
Materials Chemistry and Physics
https://doi.org/10.1016/j.matchemphys.2018.01.032
Arturo Rodríguez Gómez¹ , Marisa Moreno Rios² , Ramiro García García¹ , Ana Laura Pérez Martínez³ , José Reyes Gasga¹
¹ Universidad Nacional Autónoma de México, Instituto de Física
² Instituto Tecnológico de Pachuca,
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Substrate chemistry, Substrate surface profile, Silicon quantum dots, RPECVD, HRTEM
Abstract: By using a remote plasma enhanced chemical vapor deposition system, we grow a silicon rich silicon nitride thin film on the surface of five different substrates: silicon wafer, fused silica, highly oriented pyrolytic graphite, muscovite mica and potassium chloride. By means of high-resolution transmission electron microscopy we studied the influence that each substrate has on the auto-formation of silicon quantum dots (=4.2 nm) embedded in the grown film. We conjecture that the growth of the film is carried out by the formation of highly reactive intermediates that are chemisorbed on the substrate surface. We conclude proposing the hypothesis that the substrate surface profile has minimal influence on the growth of a silicon nitride thin film that can embed silicon quantum dots.

Optimisation and simulation of an e-bike manufacturing system: the case of a small assembly factory
International Journal of Service and Computing Oriented Manufacturing
https://doi.org/10.1504/IJSCOM.2018.091618
Pedro González Hernández¹ , Aida Huerta Barrientos¹ , Idalia Flores De La Mota¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: electric bicycles, sustainable transportation, optimisation via simulation, manufacturing throughput, discrete event-simulation, Anylogic™, decision-making, OpQuest™
Abstract: The production possibilities of electric bicycles range from simple assemblies to in-plant production of main components such as the engine or frame. In Mexico, small companies were the first to produce e-bikes; however, this sector faces the lack of theoretical tools for the design and implementation of their manufacturing systems. The purpose of this study was to develop a simulation model of an e-bike manufacturing system that maximises the system productivity. The model was developed using the DES methodology proposed by Jerry Banks and was implemented in Anylogic™ software. The design and analysis of experiments was performed using Minitab® software. The simulation time was defined according to the user, so the working time was 160 hours per month, producing a daily unit. The results indicated that the maximum system productivity was 300 units per year. The best times achieved were: 2.35 units per hour, for the material flow, for welding 1 h, for the turning process 0.58 h and finally for the electrical assembly 0.66 h.

Study of the effect of pipe materials and mixing phenomenon on trihalomethanes formation and diffusion in a laboratory-scale water distribution network
Water Science and Technology: Water Supply
https://doi.org/10.2166/ws.2017.103
Rojacques Mompremier ¹ , Óscar Arturo Fuentes Mariles¹ , Kebreab Ghebremichael ² , Ana Elisa Silva Martínez³ , José Elías Becerril Bravo¹
¹ Universidad Nacional Autónoma de México, Instituto de Ingeniería
² University of South Florida, Patel College of Global Sustainability
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: laboratory-scale, mixing, trihalomethanes (THM), water distribution network
Abstract: The objective of this study was to evaluate the factors that affect the formation and diffusion of disinfection by-products, especially trihalomethanes (THM), in a laboratory-scale water distribution network constructed with three different pipe materials. Sampling locations were chosen on the basis of residence time, pipe material and mixing zone. Water samples were collected and analyzed for temperature, pH, total organic carbon, turbidity, free chlorine and THM. Experiments were carried out where two different flow directions at cross junctions were studied. It was observed that for incoming flow at 90° with varying flow rate, mixing was shown to be incomplete where inflows tend to bifurcate rather than mix completely. For two incoming flows in opposing direction (180°), solute mixing has shown to be perfect due to the collision of the fluid streams. The results demonstrated how THM concentration can greatly vary in the same water distribution network due to the impact of pipe material, residence time and the outcome of mixing at cross junctions.

On Short-circuit Current Calculations Including Superconducting Fault Current Limiters (ScFCLs)
IEEE Transactions on Power Delivery
https://doi.org/10.1109/TPWRD.2018.2800732
Luis Miguel Castro González¹ , Daniel Guillen ² , Frédéric Trillaud Pighi³
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
³ Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Superconducting transmission lines, Resistance, Superconducting films, Superconducting integrated circuits, Fault currents, Circuit faults, Superconducting epitaxial layers
Abstract: This paper introduces a novel modeling approach for short-circuit studies incorporating superconducting fault current limiters (ScFCLs). The conventional formulation for short circuit studies, based on symmetrical components, has been extended to include the nonlinear limiting features of the ScFCL. Indeed, this is a novel iterative modeling method that has been derived from the classical calculations of short circuits. The operating point of the ScFCL is computed in the abc reference frame, while the solution of the whole network, including all of its components, is achieved using symmetrical components. The ScFCL model, which includes various parallel-connected superconducting tapes, is derived for the positive, negative, and zero sequences. Given that the resistance of the ScFCL is nonlinear and depends on the current flow, an iterative process is used to carry out short-circuit calculations. To validate the proposed method, radial and meshed distribution networks were studied. The solutions derived from the proposed approach and the ones obtained from the electromagnetic transient software Alternative Transients Program-Electromagnetic Transients Program were compared with both solutions agreeing very well with each other. The standard IEEE 14-bus test system, slightly modified to include two ScFCLs, was additionally simulated to demonstrate the practicality of the new approach in larger networks.

Revisiting groundwater overdraft based on the experience of the Mancha Occidental Aquifer, Spain
Hydrogeology Journal
https://doi.org/10.1007/s10040-018-1735-0
Pedro Martínez Santos¹ , S. Castaño Castaño² , Antonio Hernández Espriú³
¹ Universidad Complutense de Madrid, Facultad de Ciencias Geológicas
² Centro de Estudios y Experimentación de Obras Públicas, Centro de Estudios de Técnicas Aplicadas
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Socio-economic aspects, Overdraft, Groundwater management, Climate change, Spain
Abstract: Aquifers provide a reliable freshwater source in arid and semiarid regions, where droughts are common and irrigated crops present significant water requirements, so intensive pumping is generally needed. Over-extraction leads to dropping water tables, which in turn threatens the survival of groundwater-dependent ecosystems and water supplies. This calls for strategies to channel hydrological, environmental, agricultural, political and social change. Based on the experience of the Mancha Occidental aquifer, Spain, this paper explores some of the complexities of managing groundwater, dealing with the long-term changes that intensive groundwater use has generated in the region. The Mancha experience shows how environmental conservation may drive social and economic change at the regional scale for periods spanning several decades. What makes this case study unique, however, is the combination of social and environmental conflicts, most of which stem from the prevalence of illegal water use, and their detrimental effect on Ramsar wetlands. The situation exposed a paradox, namely that subsidies for farmers to cut down on water use were actually detrimental to the welfare of groundwater-dependent ecosystems. The unexpected (and timely) occurrence of extreme rainfall events in recent times, after 40 years of ineffective management measures and sustained environmental degradation, enabled the aquifer and its associated wetlands to recover spectacularly to a near-pristine condition. As groundwater-dependent wetlands are highly sensitive ecosystems, it is concluded that it is up to society to decide how much environmental damage can be tolerated in exchange for the social and economic benefits of groundwater-based development.

The breed and burn nuclear reactor: A chronological, conceptual, and technological review
International Journal of Energy Research
https://doi.org/10.1002/er.3854
Roberto López Solís¹ , Juan Luis François Lacouture²
¹ Instituto Nacional de Investigaciones Nucleares,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: bread and burn, depleted uranium, fast nuclear reactor, sustainability, traveling wave reactor
Abstract: Currently about 11% of the world's energy is produced in nuclear power plants; this implies the processing of uranium in order to enrich it to be suitable for "burning” in a nuclear reactor. Besides other environmental and monetary costs involved in the whole nuclear fuel cycle, the enrichment process has the disadvantage of producing depleted uranium as a sub-product that has no wide use and is essentially stockpiled. One strategy to deal with this issue is to design a nuclear reactor that can run mostly on depleted uranium by breeding its own fissile fuel from it. Even though this concept could sound innovative or new, the truth is that it has been in the thought of the nuclear engineers since the 50s. In the present paper, the breed & burn (B&B) reactor concept is reviewed, as well as its origins, evolution up to present, and its main technical features. The objectives of this review are as follows: (1) to summarize the history of the development of B&B reactors, (2) to compare different B&B concepts based on a systematic approach under selected technical features, and (3) to bring out current trends and future directions on this technology. It is expected that this review will help the nuclear engineering community in general, and newcomer researchers in the field, to get an overview about the B&B reactors and how to direct a research in this direction.

Seismic imaging and attribute analysis of chicxulub crater central sector, Yucatán platform, Gulf of Mexico
Geologica Acta
http://dx.doi.org/10.1344/GeologicaActa2018.16.2.6
Iza Canales García¹ , Jaime Urrutia Fucugauchi² , Joaquín Eduardo Aguayo Camargo¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Geofísica

Keywords: Chicxulub Crater. Structure. Stratigraphy. Seismic attributes. Yucatán Platform. Gulf of Mexico
Abstract: Chicxulub Crater, formed ~66Ma ago by an asteroid impact on the southern Gulf of Mexico, is the best preserved of the three large multi-ring basins in the terrestrial record. The crater structure is characterized by a semi-circular concentric ring pattern, marking the crater basin, peak ring, terrace zone and basement uplift. Analysis of a grid of 19 seismic reflection profiles using seismic attributes, marker horizons, contour surfaces and 3-D views is used to investigate the stratigraphy of the central zone. We used interactive software and routine applications to map the impact breccias, breccia-carbonate contact and post-impact carbonates. Four horizons marked by high-amplitude reflectors representing high-impedance contrasts were identified and laterally correlated in the seismic images. Complex trace attribute analysis was applied for petrophysical characterization. Surface contour maps of base and top of stratigraphic packages were constructed, which mapped the impactites and post- and pre-impact carbonate stratigraphy. Basin floor, marked by the contact between the impact breccias and overlying carbonates is shown by laterally discontinuous high-amplitude reflectors. Discontinuous scattered reflectors interpreted as the upper breccias beneath the crater floor, have an average thickness of ~300msm. The Paleogene sedimentary units are characterized by multiple reflectors with lateral continuity, which contrast with the seismic response of underlying breccias. The basal Paleocene sediments follow the basin floor relief. Upwards in the section, the carbonate strata are characterized by horizontal reflectors, which are interrupted by a regional unconformity. Onlap/downlap packages over the unconformity record a period of sea level change.

The Mexican National Seismological Service: An Overview
Seismological Research Letters
https://doi.org/10.1785/0220170186
Xyoli Pérez Campos¹ , Víctor Hugo Espíndola¹ , Jesús Pérez ¹ , Jorge Estrada ¹ , Caridad Cárdenas Monroy¹ , Delia Bello ¹ , Adriana González López¹ , Daniel González Ávila¹ , Moisés Gerardo Contreras Ruiz¹ , Rafael Maldonado ¹ , Yi Tan ¹ , Iván Rodríguez Rasilla¹ , Miguel Ángel Vela Rosas¹ , José Luis Cruz ¹ , Arturo Cárdenas ¹ , Fernando Navarro Estrada¹ , Alejandro Hurtado ¹ , Antonio de Jesús Mendoza Carbajal¹ , Edgar Montoya Quintanar² , Miguel A. Pérez Velázquez²
¹ Universidad Nacional Autónoma de México, Instituto de Geofísica
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: earthquakes, Mexico, faults
Abstract: The Servicio Sismológico Nacional (SSN, Mexican National Seismological Service) has a history of 107 yrs. In the last 13 yrs, the SSN has gone through a significant modernization process, involving the installation of new broadband stations with colocalized accelerometers, seismometers, and Global Positioning System (GPS) receivers. New collaborations with other Mexican regional networks helped increase the number of stations from which the SSN receives data. In this article, we present the current backbone broadband network configuration; data flow from the stations to the automatic and manual publication of the earthquake location and magnitude; and the seismic catalog, which includes more than 105,000 events since 1900. A clear example of the successful performance of this network is the recording of the 8 September 2017 Mw 8.2 earthquake, located in the Gulf of Tehuantepec. We present the signals of 52 of the 63 SSN broadband stations that recorded the event in real time. This earthquake represents the largest recorded in Mexico by a comprehensive national network.

Proposal of Criteria for the Evaluation of Precision and Force in Hand Prostheses
Journal of Mechanics in Medicine and Biology
http://dx.doi.org/10.1142/S0219519418500100
Julio Díaz Montes¹ , Jesús Manuel Dorador González²
¹ Universidad Autónoma del Estado de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Prosthesis evaluation, prosthesis precision, prosthesis force, evaluation criteria, prosthetic hands
Abstract: There are indicators useful to measure the grasp quality of prostheses, two of them are the force that can be reached, and the precision needed to grasp an object. It is important to evaluate force and precision in hand prostheses because these characteristics are directly related to its performance and to the activities that can be done with it. Nowadays, there are no available criteria to evaluate these two characteristics. Existing criteria can be applied only in particular situations and can be applied only to a few prosthetic devices to obtain a general evaluation. This paper presents a proposal for criteria able to evaluate precision and force in-hand prosthetic devices. These criteria have three main original characteristics: Each system in the prosthesis is evaluated individually; quantitative information about its performance is obtained; the criteria can be used for evaluating most of the existing prosthetic devices. In order to show the application and use of the criteria the evaluation of two devices is presented: CDMIT© and SmartHand©. Prosthesis evaluation results show that both prosthesis have some particular aspects that can be improved, and thus reach a higher force and better precision. Criteria presented in this paper serve for stablishing a framework useful for compare several prosthesis in various aspects.

A Phasor Estimation Algorithm based on Hilbert Transform for P-class PMUs
Advances in Electrical and Computer Engineering
https://doi.org/10.4316/AECE.2018.03013
José Roberto Razo Hernández ¹ , Martin Valtierra Rodriguez² , David Granados Lieberman¹ , Guillermo Tapia Tinoco¹ , Juan Ramón Rodríguez Rodríguez³
¹ Instituto Tecnológico Superior de Irapuato, Facultad de Ingeniería Electromecanica
² Universidad Autónoma de Querétaro, Facultad de Ingeniería campus San Juan del Río.
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: error compensation, Hilbert space, IEEE Standards, phasor measurement unit, power systems
Abstract: Phasor measurement units (PMUs) play an important role in many applications of power systems. In order to ensure a reliable performance, the phasor estimation algorithm has to satisfy a set of requirements stated in the IEEE Standard C37.118.1, which establishes the test conditions and requirements for steady-state and dynamic conditions. There, two classes of performance, P and M, can be found. In general, P-class is intended for applications that require fast response and M-class is used when greater precision is necessary. In this paper, a novel algorithm based on Hilbert transform for phasor estimation in compliance with the IEEE standard C37.118.1 for P-class is proposed. Advantages of the proposal are a fast response and a low computational burden due to the HT implementation as a low-order filter of one cycle. Further, two low-complex strategies of compensation are proposed. The proposal is validated using all the test conditions specified in the IEEE Standard C37.118.1. Besides that, real voltage and current signals of an electrical system are analyzed. The obtained results demonstrate that the new proposal can meet all the requirements for P-class performance.

Colorectal cancer: Causes and evidence of chemopreventive treatments
Current Pharmaceutical Biotechnology
https://doi.org/10.2174/1389201020666181226112712
Emmanuel Pérez Escalante¹ , Raquel Cariño Cortés² , Eduardo Fernández Martínez² , Mario Ortiz ² , Víctor Manuel Muñoz Pérez² , Isabel Sánchez Crisóstomo² , Luis Jiménez Ángeles³
¹ Universidad Autónoma del Estado de Hidalgo, Departamento de Alimentos
² Universidad Autónoma del Estado de Hidalgo, Departamento de Medicina
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Colorectal cancer, chemoprevention, molecular mechanisms, natural compounds, carcinogenic compounds, microbiota
Abstract: Background: Colorectal cancer (CRC) is the second and third most frequent cancer in women and men, respectively; indeed, CRC is placed as the fourth world's most deadly cancer (after lung, liver, and stomach cancer). The incidence of CRC is strongly influenced by nutrition and the high fat/high carbohydrate Western-style diet. CRC is one of the most intensively studied cancer types, partly because of its high prevalence, but also because of the existence of its precursor lesions, tubular or villous adenomas, and more recently serrated adenomas. The morphological steps in the adenomacarcinoma sequence have been elucidated at a molecular level, which allow the identification of the genes responsible for CRC. Review and Conclusions: The main aim of this review is to provide data regarding the pathophysiological characteristics, molecular mechanisms as well as carcinogenic and chemopreventive agents for CRC, with emphasis on evidence supporting their efficacy. These compounds may modulate multiple signaling pathways involved in cell proliferation and apoptosis in transformed cells, they also enhance the host immune system and favor an effective treatment. Despite promising results from experimental studies, only a limited number of these compounds have been tested in clinical trials. The mechanistic spectrum and specificity of the action of phytochemicals represent a complex and evolving field of research.

Real-power economic dispatch of AC/DC power transmission systems comprising multiple VSC-HVDC equipment
International Journal of Electrical Power & Energy Systems
https://doi.org/10.1016/j.ijepes.2018.11.018
Luis Miguel Castro González¹ , José Horacio Tovar Hernández² , Néstor González Cabrera¹ , Juan Ramón Rodríguez Rodríguez¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Instituto Tecnológico de Morelia, Programa de Graduados e Investigación en Ingeniería Eléctrica (PGIIE)

Keywords: AC/DC power systems, Lagrange multipliers, Incremental transmission loss, Real-power economic dispatch, VSC-HVDC equipment, VSC stations
Abstract: This paper presents a practical approach for the real-power economic dispatch of AC/DC power transmission systems formed by VSC-HVDC equipment. It uses the Lagrange multipliers method combined with a comprehensive representation of the AC/DC power system. The power losses of the AC systems, DC grid and power converters are considered in this novel formulation by using incremental transmission loss factors. For realistic solutions, the different control strategies of the power converters forming any VSC-based power grid are considered. Interestingly, this approach permits to conclude that the AC grids coupled to converters charged with DC voltage control define the nodal marginal prices in the DC network, and in turn, the energy prices in the VSC-connected passive grids are inherited from the DC network. Overall, this modelling approach yields great flexibility to model any arbitrary VSC-based HVDC power grid interconnecting various AC systems. The developed method has been validated using a two-terminal VSC-HVDC network interconnecting two otherwise independent AC grids. Its results are compared against those obtained by the sequential quadratic programming method available in the optimisation toolbox of Matlab©, with both solutions exhibiting differences inferior to 0.30% in the total generation costs, therefore concurring very well between each other. The practicality of this approach is also demonstrated by carrying out the real-power economic dispatch of an AC/DC transmission system comprising seven VSC units which give rise to a thirteen-node DC grid.

A new method to assess the contribution of VSC-HVDC connected wind farms to the primary frequency control of power networks
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2017.08.011
Luis Miguel Castro González¹ , Enrique Acha Daza²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Tampere University of Technology, Department of Electrical Engineering

Keywords: DFIG, PMSG, Primary frequency control, Newton–Raphson method, Post-disturbance conditions, Power imbalances, Wind farms, Variable speed wind turbines, VSC-HVDC links
Abstract: This paper introduces a new method to assess the contribution of VSC-HVDC connected wind farms to the primary frequency control (PFC) of power networks. This is a formulation that enables the estimation of the post-disturbance conditions of the power system, including its electrical frequency, after the incidence of power imbalances, where various VSC-HVDC connected wind farms may be simultaneously simulated. As opposed to a full dynamic simulation, which may be time-consuming, the developed method resorts to modelling all power system components for the PFC time frame by using enhanced steady-state power-flow models which are solved for a power system operating point that agrees well with the operating conditions of the network after the action of the PFC. Therefore, models of DFIG and PMSG are first derived by following a proposed procedure for the determination of the frequency regulation of the wind turbines, often called statism, whose value varies with the wind speed, as opposed to that of conventional power plants which is constant. Because the power reserve of the wind generators is used to counteract the frequency deviations in the AC power network, a VSC-HVDC link model is also developed which enables a free power transfer to conform to the output power of the wind farm. The proposed method is validated using a 9-bus power system comprising a 120-MW VSC-HVDC connected wind farm and whose results are compared against those computed by a full time-domain dynamic simulation, obtaining a very good agreement between the two quite distinct approaches where, for instance, the post-disturbance system frequency computed by the proposed method only differs by 0.092% with respect to that obtained by the full dynamic simulation. The IEEE 57-bus test system, slightly modified to incorporate two VSC-HVDC connected wind farms, is also simulated to show that the impact of the frequency regulation of the wind farms on the PFC may be assessed in a very quick, effective manner.

Telemanipulation of cooperative robots: a case of study
International Journal of Control
https://doi.org/10.1080/00207179.2017.1313455
Javier Pliego Jiménez¹ , Marco Antonio Arteaga Pérez²
¹ CICESE, División de Física Aplicada
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Telemanipulation, adaptive control, force control, cooperative robots
Abstract: This article addresses the problem of dexterous robotic grasping by means of a telemanipulation system composed of a single master and two slave robot manipulators. The slave robots are analysed as a cooperative system where it is assumed that the robots can push but not pull the object. In order to achieve a stable rigid grasp, a centralised adaptive position-force control algorithm for the slave robots is proposed. On the other hand, a linear velocity observer for the master robot is developed to avoid numerical differentiation. A set of experiments with different human operators were carried out to show the good performance and capabilities of the proposed control-observer algorithm. In addition, the dynamic model and closed-loop dynamics of the telemanipulation is presented.

Analysis and design of systems driven by finite-time convergent controllers: practical stability approach
International Journal of Control
https://doi.org/10.1080/00207179.2016.1255354
Antonio Rosales ¹ , Yuri Shtessel ¹ , Leonid Fridman Golredich²
¹ The University of Alabama, Department of Electrical and Computer Engineering
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Finite-time convergence, sliding-mode control, frequency-domain analysis, stability margins
Abstract: A concept of the practical stability margins for systems driven by finite-time convergent (FTC) controllers, including sliding-mode/higher order sliding-mode (HOSM) controllers, is proposed. These margins are based on the system's tolerance to self-sustained oscillations with certain amplitude and frequency limits. The practical stability margins are introduced as the maximal gain increase or/and the maximal phase lag added to the frequency characteristic of the linear part of the open-loop system that yields acceptable loss of system's stability/performance in terms of admissible parameters of self-sustaining oscillations. It is proposed using the describing function-harmonic balance technique for the identification of the practical stability margins. To ensure the desired practical stability margins, linear dynamics compensators are designed and added in cascade to FTC controllers. The proposed approach is verified on numerous examples.

Geology and radiometric dating of Quaternary monogenetic volcanism in the western Zacapu lacustrine basin (Michoacán, México): implications for archeology and future hazard evaluations
Bulletin of Volcanology
https://doi.org/10.1007/s00445-018-1193-5
Nanci Reyes Guzmán¹ , Claus Siebe ¹ , Magdalena Oryaëlle Chevrel² , Marie Noëlle Guilbaud¹ , Sergio Salinas ³ , Paul Layer ⁴
¹ Universidad Nacional Autónoma de México, Instituto de Geofísica
² Université Clemont Auvergne, Laboratoire Magmas et Volcans
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁴ University of Alaska, Department of Geology and Geophysics

Keywords: Zacapu basin, Michoacán-Guanajuto volcanic field, Quaternary, Monogenetic cluster, Radiocarbon, 40Ar/39Ar dating, Malpaís
Abstract: The Zacapu lacustrine basin is located in the north-central part of the Michoacán-Guanajuato volcanic field (MGVF), which constitutes the west-central segment of the Trans-Mexican Volcanic Belt. Geological mapping of a 395 km2 quadrangle encompassing the western margin of the basin, 40Ar/39Ar and 14C radiometric dating, whole-rock chemical and petrographic analyses of volcanic products provide information on the stratigraphy, erupted volumes, age, and composition of the volcanoes. Although volcanism in the MGVF initiated since at least 5 Ma ago, rocks in the western Zacapu lacustrine basin are all younger than ~ 2.1 Ma. A total of 47 volcanoes were identified and include 19 viscous lava flows (~ 40 vol.%), 17 scoria cones with associated lava flows (~ 36 vol.%), seven lava shields (~ 15 vol.%), three domes (~ 6 vol.%), and one maar (~ 2 vol.%). Erupted products are dominantly andesites with 42 km3 (~ 86 vol.%) followed by 4 km3 of dacite (~ 8 vol.%), 1.4 km3 of basaltic trachy-andesite (~ 3 vol.%), 1 km3 of basaltic andesite (~ 2 vol.%), and 0.14 km3 of rhyolite (~ 0.3 vol.%). Eruptive centers are commonly aligned ENE-WSW following the direction of the regional Cuitzeo Fault System. Over time, the high frequency of eruptions and consequent accumulation of lavas and pyroclastic materials pushed the lake’s shore stepwise toward the southeast. Eruptions appear to have clustered through time. One cluster occurred during the Late Pleistocene between ~ 27,000 and ~ 21,300 BC when four volcanoes erupted. A second cluster formed during the Late Holocene, between ~ 1500 BC and ~ AD 900, when four closely spaced monogenetic vents erupted forming thick viscous ‘a’a to blocky flows on the margin of the lacustrine flats. For still poorly understood reasons, these apparently inhospitable lava flows were attractive to human settlement and eventually became one of the most densely populated heartlands of the pre-Hispanic Tarascan civilization. With an average eruption recurrence interval of ~ 900 years during the Late Holocene the western Zacapu lacustrine basin is one of the most active areas in the MGVF and should hence be of focal interest for regional volcanic risk evaluations.

A Semi-global Exponentially Convergent Tracking Controller for Robot Manipulators using Position Feedback
IFAC-PapersOnLine
https://doi.org/10.1016/j.ifacol.2018.07.304
Pablo Becerra Morales¹ , Yu Tang Xu¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Modular design, nonlinear controller, contraction analysis, robot manipulator, semi-global exponential convergence
Abstract: A modular design of tracking controller for robot manipulators using only position feedback based on contraction analysis is provided. A global exponentially convergent state-feedback tracking controller and a semi-global exponentially convergent reduced-order observer are devised separately first. Then the semi-global exponentially convergent position feedback controller is obtained by combining the controller/observer modules in a certainty equivalence fashion without the redesign of these modules. It is showed that this controller presents a simpler gain tuning than those based on Lyapunov or passivity theory. Numerical simulations are carried out to illustrate the theoretical results and to verify the controller performance.

A motion-planning system for a domestic service robot
Trudy SPIIRAN
https://doi.org/10.15622/sp.60.1
Marco Negrete ¹ , Jesús Savage Carmona¹ , Luis Contreras Toledo²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Tamagawa University, Advance Intelligence and Robotics Research Center

Keywords: autonomous navigation, behavior-based robotics, domestic service robots, path planning
Abstract: Service robots are intended to help humans in non-industrial environments such as houses or offices. To accomplish their goal, service robots must have several skills such as object recognition and manipulation, face detection and recognition, speech recognition and synthesis, task planning and, one of the most important, navigation in dynamic environments. This paper describes a fully implemented motion-planning system which comprehends from motion and path planning algorithms to spatial representation and behavior-based active navigation. The proposed system is implemented in Justina, a domestic service robot whose design is based on the ViRBot, an architecture to operate virtual and real robots that encompasses serveral layers of abstraction, from low-level control to symbolic planning. We evaluated our proposal both in simulated and real environments and compared it to classical implementations. For the tests, we used maps obtained from real environments (the Biorobotics Laboratory and the Robocup@Home arena) and maps generated from obstacles with random positions and shapes. Several parameters were used for comparison: the total traveled distance, the number of collisions, the number of reached goal points and the average execution speed. Our proposal performed significantly better both in real and simulated tests. Finally, we show our results in the context of the RoboCup@Home competition, where the system was successfully tested.

On Short-circuit Current Calculations Including Superconducting Fault Current Limiters (ScFCL)
IEEE Transactions on Power Delivery
https://doi.org/10.1109/TPWRD.2018.2800732
Luis Miguel Castro González¹ , Daniel Guillén Aparicio² , Frédéric Trillaud Pighi³
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Tecnológico de Monterrey, Ingeniería Eléctrica y Electrónica
³ Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Fault currents, Newton-Raphson method, nodal impedance matrix, short-circuit studies, superconducting fault current limiters (SCFCL), symmetrical components
Abstract: This paper introduces a novel modeling approach for short-circuit studies incorporating superconducting fault current limiters (ScFCLs). The conventional formulation for short circuit studies, based on symmetrical components, has been extended to include the nonlinear limiting features of the ScFCL. Indeed, this is a novel iterative modeling method that has been derived from the classical calculations of short circuits. The operating point of the ScFCL is computed in the abc reference frame, while the solution of the whole network, including all of its components, is achieved using symmetrical components. The ScFCL model, which includes various parallel-connected superconducting tapes, is derived for the positive, negative, and zero sequences. Given that the resistance of the ScFCL is nonlinear and depends on the current flow, an iterative process is used to carry out short-circuit calculations. To validate the proposed method, radial and meshed distribution networks were studied. The solutions derived from the proposed approach and the ones obtained from the electromagnetic transient software Alternative Transients Program-Electromagnetic Transients Program were compared with both solutions agreeing very well with each other. The standard IEEE 14-bus test system, slightly modified to include two ScFCLs, was additionally simulated to demonstrate the practicality of the new approach in larger networks.

SAR analysis of the Larsen-C A-68 iceberg displacements
International Journal of Remote Sensin
https://doi.org/10.1080/01431161.2018.1508921
Flavio Parmiggiani ¹ , Miguel Moctezuma Flores² , Lorenzo Guerrieri ¹ , M. L. Barragliere ³
¹ Institute of Atmospheric Sciences and Climate, Bologna
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Italian Space Agency, COSMO-SkyMed Mission

Keywords:
Abstract: The fracture of the Larsen C ice shelf, which has been continuously monitored since the final months of 2016, started to grow rapidly in 2017 and, in February 2017, only a 20 km ice strip kept a huge section of the shelf attached to the Antarctic Peninsula. The final collapse, expected in 2017, occurred indeed between July 10 and July 12, with a loss of an area of some 6,000 km2, corresponding to about 9–12% of the entire shelf. Following US National Ice Center (NIC) criteria, the calved iceberg was named ‘A-68’. Responding to the ASI ‘COSMO-SkyMed Open Call for Science Initiative’, this paper presents a study of the initial phase of iceberg A-68 melting process and drifting trajectory. The analysis covers a period of six months and makes use of a set of COSMO-SkyMed ScanSAR Huge images.

Development and characterization of hydrophobic anodized aluminum layer to act as a long-lasting protective film in corrosion
Surface and Interface Analysis
https://doi.org/10.1002/sia.6437
Rebecca Jaimes ¹ , Alba Covelo Villar¹ , Sandra Rodil ² , María del Pilar Corona Lira¹ , Alejandro Cuauhtémoc Ramírez Reivich¹ , Miguel Ángel Hernández Gallegos¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales

Keywords: ?-irradiation, anodized aluminum, fluoropolymer, hydrophobicity
Abstract: This work focuses on the development of a novel hydrophobic process for anodized aluminum AA2024-T3 which consists of a combination of corrosion inhibitors: sodium metavanadate with a ?-irradiated fluoropolymer. The anodizing films, formed in sulfuric acid media, were sealed by using different aqueous solutions such as boiling water, potassium dichromate, and cerium nitrate. The corrosion resistance results obtained by electrochemical impedance spectroscopy (EIS) showed that samples sealed with Ce(NO3)3 had a higher average value of total impedance of 1011 O cm2 obtained at low frequencies in 0.1 M NaCl solution. Water contact angle measurements revealed best results at 128.8°. X-ray photoelectron microscopy in conjunction with scanning electron microscopy indicated the formation of a layer of fluoro compound above the anodized aluminum. X-ray diffraction, infrared spectroscopy, and differential scanning calorimetry demonstrated thermal modifications of the ?-irradiated fluoropolymer.

Characterization of superficial modification of ferrous rusted substrates subjected to dechlorination-electrochemical process
Journal of Adhesion Science and Technology
https://doi.org/10.1080/01694243.2017.1409854
Jesús Rafael González Parra¹ , Alba Covelo Villar¹ , R. J. Ramírez ¹ , A. Tejeda ² , A. Ortega ³ , Miguel Ángel Hernández Gallegos¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
³ Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares

Keywords: Carbon steel, SEM, X-ray diffraction, rust, dechlorination
Abstract: Preservation of archaeological artefacts after their removal from saline media is a difficult task due to the chloride content of the oxide layers which are unstable in atmospheric conditions, especially if the relative humidity exceeds 85%. For this reason, removal of chlorides from rust layers is one of the priorities of conservationists or restorers of historical artefacts. However, removal of chloride ions is not an easy procedure because of the many considerations involved in the process. In this research, artificially pre-rusted iron samples and an actual historical cannonball were subject to a dechlorination process in a potassium hydroxide solution to measure constant chloride release in a bulk solution. After the chloride removal process, a commercial protective layer was applied to the rust for stabilization purposes. It was calculated that the kinetics of the dechlorination process is driven by diffusion behaviour following Fick’s second law. When this diffusion process prevails, the dechlorination extraction affects the integrity of rust layers as is demonstrated with scanning electron microscopy and X-ray diffraction analyses. It was proven that the chloride removal procedure causes the studied iron layers to stiffen, provoking superficial modification and, in some cases, fractures of the rust. By means of electrochemical impedance spectroscopy it was calculated that the magnitude of the positive effect of the dechlorinated samples depends on the protective features of the rust. Therefore, this research reveals that an efficient chloride removal procedure depends on the electrochemical properties of the dechlorination process and the initial morphology of the iron rust.

MSP: Providing location privacy in WLAN networks with a MAC Swapping Protocol
Computer Networks
https://doi.org/10.1016/j.comnet.2018.03.030
Oscar Arana ¹ , Francisco Javier García Ugalde² , Javier Gómez ² , Víctor Rangel Licea²
¹ Universidad Nacional Autónoma de México, Instituto de Investigación en Matemáticas Aplicadas y Sistemas
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Location privacy, MAC exchange, Anonymity, Location estimation
Abstract: Location privacy has been widely studied in the context of location-based services (LBS). However, a far more serious location privacy threat arises when malicious eavesdroppers listen to wireless transmissions from an unsuspecting mobile user in order to pinpoint his location and figure out his identity. This new scenario is known as location estimation (LE). While there are several strategies to mitigate the threats posed by LBS scenarios, only a few researchers deal with countermeasures for LE scenarios. This paper proposes MSP, a MAC Swapping Protocol that allows two mobile users to discreetly exchange their MAC addresses without malicious eavesdroppers being able to detect it. In this way, although potential eavesdroppers can still pinpoint the location of a transmitting node, they will get its identity wrong. Over time, MSP eliminates the eavesdroppers’ ability to link the position and identity of a transmitting source. In contrast to related research, the identity exchange in MSP takes into account information from the mobile users’ physical and MAC layers simultaneously, so an attack in one layer does not expose the identity exchange in the other layer. In order to provide location privacy, MSP uses two algorithms. The first algorithm works at the physical layer, allowing two mobile nodes to decide when and where to exchange their MAC addresses. The second algorithm uses virtual interfaces to guarantee that the identity exchange does not exhibit any abnormal behavior at the MAC layer. Test-bed and simulation experiments demonstrate that MSP is able to guarantee location privacy even with attackers eavesdropping at the physical and MAC layers simultaneously.

Student course evaluation: a process-based approach
Australasian Journal of Engineering Education
https://doi.org/10.1080/22054952.2018.1557099
Engelberth Soto Estrada¹ , Ann Godelieve Wellens Purnal² , Jairo Gómez Lizarazo¹
¹ EIA University, Department of Civil Engineering
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Student evaluation of teaching, process analysis, teaching effectiveness, Colombia
Abstract: One of the most commonly used forms of educational evaluation is by means of student surveys. In Colombia, as in all countries of Latin America, student course evaluations in higher education remain focused on teaching performance, while the results of these instruments are frequently used as an indicator (and in some cases the only indicator) of quality and effectiveness of both undergraduate and postgraduate programmes. This article argues that the teacher-centred evaluation provides insufficient information to improve the quality of higher education. Therefore, a process-based evaluation model (PBEM) is proposed for a Colombian university offering engineering programmes. The PBEM is intended to provide reliable information on teaching effectiveness, but also about other factors influencing teaching and learning such as course design. The PBEM was designed in accordance with the EIA University’s pedagogical model, which encompasses competencies, values, and key areas of transversal learning. The implementation of the instrument started in 2015. Since then, more than 2500 lecture groups have been evaluated. This article addresses some key issues and challenges related to the implementation of this evaluation model.

Super-Twisting Algorithm in presence of time and state dependent perturbations
International Journal of Control
https://doi.org/10.1080/00207179.2016.1269952
I. Castillo ¹ , Leonid Fridman Golredich¹ , Jaime Alberto Moreno Pérez²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Sliding modes, super-twisting algorithm
Abstract: In this paper, generalized Super-Twisting Algorithm is applied to a class of systems whose perturbation and uncertain control coefficient are time- and state-dependent. A non-smooth strict Lyapunov function is used to obtain the conditions for the global finite-time stability and to estimate the time of convergence.

Reduced light transmission in an optical fiber embedded in a reinforced concrete beam under flexural loading
Journal of Optical Technology
https://doi.org/10.1364/JOT.85.000570
J. E. González Tinoco¹ , Héctor J. Guzmán Olguin¹ , Sergei Khotiaintsev ¹ , María C. López Bautista¹ , M. A. Zúñiga Bravo¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fiber optic sensors, Light beams, Light transmission, Multimode fibers, Optical fibers, Optical sensing
Abstract: The cause for the decrease in light transmission in optical fibers embedded in reinforced concrete beams with flexural deformation was investigated. It was determined that optical fibers in such beams have multiple bends as a result of chaotic movement of gravel particles during the shrinkage of the concrete mixture. The results of field and model experiments are presented, which indicate that the probable reasons for the decrease in light transmission in optical fibers embedded in reinforced concrete beams, observed when the latter are bent, are local changes in the parameters of the optical fibers in regions with sharp bends accompanying beam deformation.

Response spectra generation using a fractional differential model
Soil Dynamics and Earthquake Engineering
https://doi.org/10.1016/j.soildyn.2018.09.006
Armando Hermosillo Arteaga¹ , Miguel Pedro Romo Organista² , Roberto Magaña Del Toro²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Motion equation, Earthquake, Response spectrum, Response spectra generation, Fractional derivative, Fractional differential equation
Abstract: Over the past three decades, fractional calculus has been of increasingly interest to geotechnical researchers for studying time-dependent problems such as those that arise in Rheology. From previous investigations on Rheology (i.e., [1,2]) it has been shown that the accuracy requirements and the merits of hereditary phenomena with long memory make the fractional calculus an attractive mathematical tool for developing constitutive models. Although the advantages of this mathematical tool were mainly brought out by applying it to rheological problems, the authors are certain that fractional calculus can be used as alternative to integer models for evaluating design response spectra to carry out aseismic structural designs. Accordingly, this paper presents an alternative to generating response spectra of recorded or synthetic time histories using fractional differential equations (FDEs). As it is well known an acceleration response spectrum is the locus of the absolute value of maxima response accelerations of a single degree of freedom system (SDFS) for different natural periods and at a constant damping. A loci of response spectra is developed repeating the above mentioned computations for a set of different damping values. As broadly known, the equation of motion of the simple oscillator is obtained from the equilibrium of inertia, damping, elastic forces and dynamic excitation. This force equilibrium equation yields to a second order differential equation. In this paper only the first order derivative (velocity) of the second order differential equation of motion for the single degree of freedom system is considered fractional. Varying the order of the first order derivative (velocity) influences directly the damping capacity and tangentially the stiffness of the simple oscillator. Accordingly, its natural frequency and spectral ordinates of its response will be modified. As will be shown in the paper these modifications lead to more severe seismic conditions raising the question on the appropriateness of current design spectra specified in construction building codes and used in practice. Pondering this issue, the authors considered that it would be of great interest to use a fractional differential equation to model the simple damped oscillator and develop an alternative way to compute response spectra, particularly if these are more critical than those computed by currently used procedures. Thus, in this work a fractional differential equation (FDE) is used to generate response spectra of a number of recorded acceleration time histories. Furthermore, it is shown that the exponent a of the velocity term (dx/dt into dax/dta) of the FDE can be expressed in terms of the SDFS stiffness and damping parameters providing the exponent a physical meaning. Also, it is shown that the SDFS damping ratio is frequency dependent.

Contraction analysis for fractional-order nonlinear systems
Chaos, Solitons & Fractals
https://doi.org/10.1016/j.chaos.2018.10.030
Marcos Ángel González Olvera¹ , Yu Tang Xu²
¹ Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fractional-order Systems, Stability, Convergence Analysis, Contraction Analysis, Nonlinear Fractional-Order Systems
Abstract: In this work we present a novel platform for analysis of fractional-order nonlinear systems that, from a differential analysis as well as contraction analysis point of view, gives the sufficient conditions for the mutual convergence of nearby trajectories whose distance decrease asymptotically bounded by a Mittag-Leffler vanishing function. Particular cases, such as partial contraction and contraction to a linear manifold are studied. Applications to stability analysis, adaptive control, observer design and synchronization of chaotic fractional-order systems are derived in order to demonstrate the effectiveness of the proposed paradigm.

Closing Gaps for Aircraft Attitude Higher Order Sliding Mode Control Certification via Practical Stability Margins Identification
IEEE Transactions on Control Systems Technology
https://doi.org/10.1109/TCST.2017.2753162
Chandrasekhara Bharath Panathula¹ , Antonio Rosales ² , Yuri Shtessel ³ , Leonid Fridman Golredich⁴
¹ The University of Alabama in Huntsville, Department of Electrical and Computer Engineering
² Instituto Tecnológico de Estudios Superiores de Monterrey, Campus Ciudad de México
³ The University of Alabama, Department of Electrical and Computer Engineering
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Aircraft control, frequency domain analysis, practical stability margins, sliding mode control (SMC)
Abstract: In this paper, the conventional aircraft control system certification approach based on phase margin (PM) and gain margin (GM) is extended to higher order sliding mode (HOSM) controllers. The proposed practical stability PM (PSPM) and the practical stability GM (PSGM) are used to quantify the HOSM control system robustness to unmodeled dynamics. The tools/algorithms for the identification of PSPM and PSGM are developed using describing function-harmonic balance method. A design algorithm of a cascade dynamic compensator for a dynamically perturbed HOSM control system is presented and can be used to satisfy required practical stability margins. The theoretical developments are illustrated and validated on controlling the attitude of an F-16 aircraft.

Fault detection and classification in transmission lines based on a PSD index
IET Generation, Transmission and Distribution
https://doi.org/10.1049/iet-gtd.2018.5062
Daniel Guillen ¹ , Mario Roberto Arrieta Paternina² , José Ortiz Bejar³ , Rajesh Kumar Tripathy ⁴ , Alejandro Zamora Méndez⁵ , Rubén Tapia Olvera² , Eric Téllez ⁶
¹ Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
² Universidad Nacional Autónoma de México, Facultad de Ingeniería
³ Universidad Michoacana de San Nicolás de Hidalgo,
⁴ Birla Institute of Technology and Science,
⁵ Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
⁶ Centro de Investigación e Innovación en Tecnologías de la Información y Comunicación,

Keywords:
Abstract: This study deals with the faults’ detection and classification in AC transmission lines based on power spectral density (PSD), introducing PSD in time and frequency for analysing transient information under faulted conditions. The discrete wavelet transform is used for scaling current signals in time–frequency at different decomposition levels by approximation and detail coefficients. Then, a wavelet-covariance matrix is shaped with the aim to obtain its PSD, being this the key to detect and classifying faults. Results show that the proposed method attains the detection in a short time and the classification is accomplished via the Hellinger distance, whose straightforward implementation is carried out in this study. The classification process is compared adopting different classifiers to cope with a set of signals in a time frame. Finally, the proposal is extensively assessed using real and simulated signals stemming from multiple fault cases of radial and interconnected power grids.

Memristor Based on the Contact of Two Metal Balls
IEEE Sensors Journal
https://doi.org/10.1109/JSEN.2018.2864585
Julio C. García Paniagua¹ , Pablo Roberto Pérez Alcázar²
¹ Universidad Autónoma Metropolitana, Unidad Iztapalapa
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Memristor, basic circuit element, fingerprints of memristor, memristive flux-charge, pinched hysteresis loop, v-i characterization
Abstract: The memristor was postulated as the fourth passive element in 1971. However, since the implementation of the Hewlett-Packard (HP) memristor in 2008, the role of the memristor as an element of an electrical circuit has not been explored as much as other passive elements, such as the resistor, capacitor, or inductor. This paper shows the characterization in dc and ac of a structure based on two metal balls in contact. The behavior of the device approaches three distinctive features that a memristor must have, as described by Chua. With the obtained results, we can consider that the proposed structure qualifies as a memristor and constitutes a representative of the fourth basic passive element of an electrical circuit.

Slippage effect on the dispersion coefficient of a passive solute in a pulsatile electro-osmotic flow in a microcapillary
Physical Review Fluids
https://doi.org/10.1103/PhysRevFluids.3.084503
Jaime Ernesto Muñoz ¹ , José Carlos Arcos Hernández² , Oscar Eladio Bautista Godínez² , Federico Méndez Lavielle³
¹ Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos
² Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: The hydrodynamic dispersion of a neutral solute released into a pulsatile electro-osmotic flow in a microcapillary that is affected by slippage at the wall (modeled by the Navier slip condition) is studied theoretically. The long-time Taylor dispersion is analytically derived using the homogenization method with multiple scales. The results indicate that the effective dispersion coefficient depends on a dimensionless slip length, an angular Reynolds number, the amplitude of the oscillatory component of the external electric field, and an electrokinetic parameter that relates the radius of the microcapillary with the Debye length. Our results suggest that in the presence of the Navier slip condition, the dispersivity is maximized by up to two orders of magnitude compared with that obtained through the classical no-slip condition.

Fractional-Order Closed-Loop Model Reference Adaptive Control for Anesthesia
Algorithms
https://doi.org/10.3390/a11070106
Gerardo Navarro Guerrero¹ , Yu Tang Xu¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Anesthesia; fractional systems; adaptive control
Abstract: The design of a fractional-order closed-loop model reference adaptive control (FOCMRAC) for anesthesia based on a fractional-order model (FOM) is proposed in the paper. This proposed model gets around many difficulties, namely, unknown parameters, lack of state measurement, inter and intra-patient variability, and variable time-delay, encountered in controller designs based on the PK/PD model commonly used for control of anesthesia, and allows to design a simple adaptive controller based on the Lyapunov analysis. Simulations illustrate the effectiveness and robustness of the proposed control.

Finite Element Evaluation for Adhesive Joints Dissimilar Material (Steel - Aluminum)
DYNA
https://doi.org/10.6036/8619
Celso Eduardo Cruz González¹ , Alexandre Jamiloux ² , Saúl Daniel Santillán Gutiérrez³ , Pedro González García⁴ , José Jaime Taha Tijerina⁵ , Rodrigo Romero ⁶ , Hugo Gámez Cuatzin⁴
¹ Centro de Ingeniería y Desarrollo Industrial, Dirección de Ingeniería Mecánica
² SIGMA Clemont, Campus des Cézeaux
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁴ Centro de Ingeniería y Desarrollo Industrial,
⁵ Tecnológico Nacional de México, Instituto Tecnológico de Tlalnepantla
⁶ METALSA, Departamento de Tecnología

Keywords: Adhesive, finite element simulation, stress distribution, scanning electron microscopy, foil strain gauge
Abstract: In the automotive industry the demand for the reduction of CO2 emissions and environmental issues has generated regulations such as the CAFE (Corporate Average Fuel Economy). One critical point to be addressed is the weight reduction, this can be achieved by the substrate combination that can provide light weight, strength and stiffness. Adhesive bonding, is a technology in which one of its advantages is that it can join dissimilar materials. However, for the safe operation of bonded components, it is necessary to know their mechanical behavior in order to establish suitable operating parameters. The present manuscript presents a finite element analysis for dissimilar metal (aluminum-steel) adhesive bonded joints with different adhesives (methyl methacrylate, one and two component epoxy) and different thicknesses (3.9 and 2.9 mm). The substrates and adhesives were characterized to obtain a positive identification of the material and to feed the ABAQUS® software employed in the finite element analysis. In order to validate the model, lap shear tests were performed on samples bonded with the adhesives mentioned before. To verify the amount plastic strain, strain gauges were used bonded near the overlap area. Finally, post-fracture analyzes were used to analyze the type of failure. The results, provide information related to the mechanical behavior and stress distribution of the joints. It was revealed, that the strength of the joint depends on the type of adhesive and that the shear strength is not affected by the ductility of the adhesive. Additionally, the average normal stresses are greater in the edges of the adhesive joint and are responsible for the generation of the crack as could be verified in the post-fracture analysis. Finally, extensometer analysis suggested that higher stress was concentrated in the aluminum adherend without surpassing the yield stress.

On-line estimation of switched reluctance motor parameters
International Journal of Adaptive Control and Signal Processing
https://doi.org/10.1002/acs.2877
Missie Aguado Rojas¹ , Paul Rolando Maya Ortíz² , Gerardo Espinosa Pérez²
¹ Université Paris-Sud,
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: This paper addresses the problem of on-line parameter estimation of switched reluctance motors and provides, to the best of the authors' knowledge, the first result that takes into account the dynamics of both electrical and mechanical subsystems. Based on a widely-used standard model of the motor and establishing a reasonable structure for modeling the unknown load torque, a linear parametric model is derived and a 2-stage identification scheme is proposed and implemented with the recursive least-squares algorithm with forgetting factor. It is assumed that stator voltages and currents and rotor position and speed are available through measurements. Numerical simulations and experimental tests are included for a 3-phase 12/8 switched reluctance motor. The results show a good performance of the proposed methodology, and the estimated parameters are validated through their use in a closed-loop control scheme. Key features of the proposed solution are that it does not rely on locked-rotor tests nor does it assume previous knowledge of the magnetization curves of the motor. The estimation scheme is intended to improve the performance and efficiency of currently available control algorithms, and it is potentially useful for the design of selfcommissioning switched reluctance drives, ie, drives that can automatically adjust the controller parameters for a wide range of motors and loads.

Indirect IDA-PBC for active and reactive power support in distribution networks using SMES systems with PWM-CSC
Journal of Energy Storage
https://doi.org/10.1016/j.est.2018.03.004
Oscar Danilo Montoya¹ , Walter Gil González² , Alejandro Garcés ³ , Gerardo Espinosa Pérez⁴
¹ Universidad Tecnológica de Bolívar,
² Institución Universitaria Pascual Bravo, Facultad de Ingeniería
³ Universidad Tecnológica de Pereir,
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Active and reactive power compensation, Distribution systems, Interconnection and damping assignment passivity-based control, Pulse-width-modulated current source converter, Superconducting magnetic energy storage
Abstract: In this paper an indirect interconnection and damping assignment passivity-based control (IDA-PBC) applied to the three-phase superconducting magnetic energy storage systems (SMES) is proposed to support active and reactive power in distribution systems. The SMES is connected to the distribution network using a pulse-width-modulated current source converter (PWM-CSC), due to its intrinsic current features that are more natural for controlling the current of a superconducting coil. A Hamiltonian function is selected as an hyperboloid representation taking into account the open loop dynamics of the system. The indirect control strategy is used to decouple the dynamical behavior between ac and dc side of the system, which allows to control active and reactive power independently in the ac side, while the dc side of the converter is employed as a supervisor controller for active power interchange. Simulation results demonstrate the efficiency and robustness of the proposed control methodology applied on a low-voltage distribution network under different operative conditions where the tracking errors were less than 6.2%.

Laboratory Tests of Single Frequency Networks with ATSC on Commercial Receivers
IEEE Latin America Transactions
https://doi.org/10.1109/TLA.2018.8358652
Mario Alberto Hernández Flores¹ , Jaime Huerta ² , Víctor García Garduño¹ , José María Matías Maruri¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² ,

Keywords: Advanced Television Systems Committee, ATSC, digital terrestrial television, DTT, laboratory tests, SFN, single frequency network
Abstract: This paper presents the results of laboratory tests simulating the reception in a Single Frequency Network (SFN) with ATSC on commercial receivers. The results of the commercial receivers are important because the viability of the SFNs with ATSC depends mainly of the performance of the receivers. Additionally, the basic implications of the results on the SFNs design are presented. Mexico officially adopted ATSC for Digital Terrestrial Television (DTT) service more than 10 years ago, but the analog transmissions stopped until December 31, 2015. The results of these tests can contribute to the planning of SFNs with ATSC. ATSC does not use OFDM modulation unlike others DTT systems. For this reason, the operation of a SFN with ATSC depends primarily on receiver equalizer capabilities. However, the performance of the receivers have improved over the years. The tests focus on the relationship between power and delay of the two signals received on the SFN, and the methodology includes the simulation of three reception environments: without multipath, outdoor reception and indoor reception.

Open- and Short-Circuit Fault Identification for a Boost dc/dc Converter in PV MPPT Systems
Energies
https://doi.org/10.3390/en11030616
Diego Rivelino Espinoza Trejo¹ , Ernesto Bárcenas ¹ , José E. Hernández ¹ , Guillermo Bossio ² , Gerardo Espinosa Pérez³
¹ Universidad Autónoma de San Luis Potosí, Región Altiplano
² Universidad Nacional de Río Cuarto, Applied Electronics Group
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fault diagnosis; photovoltaic systems; mppt; boost dc/dc converter
Abstract: This paper proposes a fault identification system for short and open-circuit switch faults (SOCSF) for a dc/dc converter acting as a Maximum Power Point Tracker (MPPT) in Photovoltaic (PV) systems. A closed-loop operation is assumed for the boost dc/dc converter. A linearizing control plus a Proportional-Derivative (PD) controller is suggested for PV voltage regulation at the maximum power point (MPP). In this study, the SOCSF are modeled by using an additive fault representation and the fault identification (FI) system is synthesized departing from a Luenberger observer. Hence, an FI signal is obtained, which is insensitive to irradiance and load current changes, but affected by the SOCSF. For FI purposes, only the sensors used in the control system are needed. Finally, an experimental evaluation is presented by using a solar array simulator dc power supply and a boost dc/dc converter of 175 W in order to validate the ideas this study exposes.

Design and synthesis of a 2 DOF 9-bar spatial mechanism for a prosthetic thumb
Mechanism and Machine Theory
https://doi.org/10.1016/j.mechmachtheory.2017.12.001
P. E. Ávila Hernández¹ , Francisco Cuenca Jiménez¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Optimal synthesis, Kinematic synthesis, Prosthetic thumb, Spatial mechanism
Abstract: In the last two decades, different prosthetic hands have been developed. However, little attention has been given to thumb designing. This paper presents the design and kinematic synthesis of a new 2 DOF 9-bar spatial mechanism that can be used as a prosthetic thumb focused on emulating the 5 movements of human thumb joints. The mechanism replicates the movements of the interphalangeal (IP), metacarpophalangeal (MCP) and carpometacarpal (CMC) joints, with the limitation that only the movements of the CMC joint are independent and the movements of the remaining joints are dependent on CMC movements. All the links of the mechanism are contained within an anthropomorphic shape, and its tip is capable of generating a 3D surface as working envelope. These features are the result of combining the mathematical representation of a deep knowledge of the kinematics and anthropometry of the thumb with techniques of optimal synthesis and spatial mechanisms design.

Analysis and characterization of the normal gait phases of walking Warmblood horses as a tool for the diagnosis of lameness
Pesquisa Veterinária Brasileira
https://doi.org/10.1590/1678-5150-PVB-4496
Lázaro Morales Acosta¹ , Armando Ortiz Prado¹ , Víctor Hugo Jacobo Armendáriz¹ , Raide Alfonso González Carbonell²
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad de Camagüey "Ignacio Agramonte Loynaz",

Keywords: Gait; horses; Warmblood; lameness; photogrammetry; accelerometry; equine; limb injuries; clinics
Abstract: Horses with lameness modify gait behavior, but when it is subtle, it may not be possible to identify it clinically. The objective of this research is to characterize the normal gait phases of walking Warmblood horses by combining photogrammetry and accelerometry to monitor lameness to indicate a structural or functional disorder in the extremities. The study was conducted in 23 adult male Warmblood horses. Photogrammetry was used to identify the kinematic variables of the limbs and the markers path over time; triaxial accelerometers were used to capture the orthogonal acceleration components. It was determined that only 10 horses showed a normal gait pattern, there was a 43% correspondence between the expert´s judgment and the diagnostic techniques. According to the Stashak classification of the gait phases, cycle phases to forelimb were 34/4/8/13/41, while for hind limb were 54/11/8/8/19 (% of the stride). The range of motion (ROM) of the neck, knee and fetlock joints was 45.52±5.63°, 196.04±19.7° and 209±11.52° respectively. A combination of experimental methods was used to identify the phases of gait cycle of healthy horses. There was a correspondence in the location of the points of maximum displacement of the limbs with both techniques. More detailed information on the limbs movement was obtained using the accelerometer technology. These methods are applicable to other conditions either outdoors or in the lab.

Conjugate thermal creep flow in a thin microchannel
International Journal of Thermal Sciences
https://doi.org/10.1016/j.ijthermalsci.2017.10.012
Ian Guillermo Monsivais Montoliu¹ , José Joaquín Lizardi Del Ángel² , Federico Méndez Lavielle¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: Microchannels, Thermal creep, Conjugate heat transfer, Rarified effects
Abstract: In the present work, we analyze asymptotically and numerically the conjugate heat transfer between a rarified gas flow and the lower wall of a thin horizontal microchannel. The laminar motion of the gas is originated only by the thermal creep or transpiration effect on the lower wall of the microchannel. It is well known the need to impose, in general, a variable temperature regime at the lower wall to induce the transpiration effect. Usually, it can be reached by setting a linear temperature profile as a boundary condition. However, in our case, we prefer to avoid this simplification taking into account that in practical applications, the temperature profile at the lower wall can be unknown. This case can occur, for instance, in a heat sink or a similar device with a well defined heat dissipation rate. Under this physical configuration, we can assume then that the bottom or external face of this heat sink with finite thermal conductivity is exposed to a uniform heat flux. On the other hand, the upper wall of the microchannel is subjected to a prescribed condition. The above conditions are sufficient to consider the simultaneous or conjugate heat transfer analysis of the heat conduction equation for the heat sink and the mass, momentum and energy equations for the gaseous-phase. Resulting governing equations are written in dimensionless form, assuming that the Reynolds number associated with the characteristic velocity of the thermal creep and the aspect ratio of the microchannel, are both very small. The velocity and temperature profiles for the gas phase and the temperature profiles for the solid wall are predicted as functions of the involved dimensionless parameters and the main results confirm that the phenomenon of conjugate thermal creep exists whenever the temperature of the lower wall varies linearly or nonlinearly.

Speed Control of PMSM using nature-inspired algorithms
IEEE Latin America Transactions
https://doi.org/10.1109/TLA.2018.8327429
Omar Aguilar Mejía¹ , Raúl Sosa Cortés² , C. Enriquez Ramírez³ , José Luis Templos Santos² , Hertwin Minor Popocatl¹ , Rubén Tapia Olvera⁴
¹ Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrados
² Universidad Politécnica de Tulancingo, División de Investigación y Posgrado
³ Universidad Politécnica de Tulancingo, División de Ingenierías
⁴ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bio-inspired models, PI controller, PMSM, Swarm intelligence
Abstract: A Proportional-Integral (PI) controller is a system designed to diminish the error between the desired reference value and the measured variable of the process to be regulated. The PI controller works according to two input parameters that must be calculated by a tuning process. In this work, the process is performed using intelligent swarm algorithms to seek for optimal parameters of PI controller. Three reactive, nature-inspired algorithms (bat, whale optimization and cuckoo search), were used to tune the PI controller. The control scheme based on linear regulators is used to improve the performance of the permanent magnet synchronous motor (PMSM) and to regulate the rotor speed to a desired reference value. In order to validate the effectiveness of the controller, simulation is performed under constant load condition, varying load condition and varying set speed conditions of the PMSM.

Seguridad e integración energética con Estados Unidos: de la confianza a la incertidumbre
Norteamérica Revista Académica del CISAN - UNAM
https://doi.org/10.22201/cisan.24487228e.2018.2.322
Víctor Rodríguez Padilla¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Seguridad energética, integración energética, México, Estados Unidos.
Abstract: Se analiza el proceso de integración energética con Estados Unidos, afectado por el deterioro de la relación bilateral y la incertidumbre que acompaña a Donald Trump en la Casa Blanca. El marco de referencia es la teoría de la seguridad energética y el método de análisis histórico lógi-co. Se destaca la creciente dependencia de los combustibles importados, a la que ha llevado el abandonó de criterios de autosuficiencia. Se concluye que alentar las importaciones y profundi-zar la integración van en línea con las reformas de mercado y la asociación estratégica con ese país, pero es una estrategia de alto riesgo por la excesiva dependencia a la que se ha llegado. No se requiere descartar los intercambios comerciales con Estados Unidos para mejorar la seguri-dad energética, pero sí tomar medidas precautorias frente a un suministro de energía que ha dejado de ser confiable.

Petróleo y minería: México en la senda del extractivismo
Mexican Studies / Estudios Mexicanos
https://doi.org/10.1525/msem.2018.34.3.279
Víctor Rodríguez Padilla¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Extractivismo, fiscalidad, legislación, minería, petróleo.
Abstract: En este artículo se analiza de manera empírica la política mexicana en materia de extracción de petróleo, gas natural y otros minerales para discernir su naturaleza y alcance. Se concluye que el aprovechamiento de estos recursos se inscribe en un esquema extractivista que beneficia primordialmente a las empresas del ramo y se aleja del neoextractivismo practicado por gobiernos progresistas en América Latina. Asimismo, se señala que el extractivismo petrolero se ha potenciado con la liberalización de 2013–2014. En este marco, la degradación ambiental, las tensiones sociales y el agotamiento prematuro del patrimonio geológico son considerados como males menores de un progreso irrenunciable.

Influence of the roughening method, joint configuration and adhesive thickness on the shear strength of ferritic stainless steel surfaces joined by methyl methacrylate
Revista de Metalurgia
https://doi.org/10.3989/revmetalm.120
Celso Eduardo Cruz González¹ , José D. Mosquera Artamonov² , Saúl Daniel Santillán Gutiérrez³ , Hugo Gámez Cuatzin⁴
¹ Centro de Ingeniería y Desarrollo Industrial, Dirección de Ingeniería Mecánica
² Universidad Autónoma de Nuevo León, Facultad de ingeniería Mecánica y Eléctrica
³ Universidad Nacional Autónoma de México, Facultad de Ingeniería
⁴ Centro de Ingeniería y Desarrollo Industrial,

Keywords: Design of experiments, Joint configuration, Methyl methacrylate, Shear strength, Surface roughening
Abstract: Surface roughening, joint configuration, and adhesive thickness were selected as factors to analyze, by using a 23 design of experiments, the adhesive joint of AISI 430 steel using Methyl Methacrylate. Scanning electron microscopy observations, roughness-contour measurement and wettability analysis were performed on the adherents to analyze the adhesion, roughness, surface contour and shear strength on the adhesion tests. The statistical analysis yields that the most significant variable was the surface finishing for an adjusted R2 of 90%. The difference of shear stress of 20.69 and 12.67 MPa was obtained for the mechanical and chemical roughening respectively, since the difference in wettability was around 78 and 113° for the same surface finishing. According to analyze the combination of factors for a shear stress of 21.80 MPa are mechanical roughening, single lap joint and glass beads.

Automatic remeshing algorithm of triangular elements during finite element analyses
Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería
https://doi.org/10.23967/j.rimni.2017.5.003
Armando Hermosillo Arteaga¹ , Miguel Pedro Romo Organista² , Roberto Magaña Del Toro² , Jorge Carrera Bolaños¹
¹ Universidad Nacional Autónoma de México, Facultad de Ingeniería
² Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Finite element, automatic remeshing, geotechnics, shallow strip foundation, numerical analysis
Abstract: In this paper an automatic remeshing algorithm of triangular finite elements is presented. It is well known that the element sizes of the mesh play an important role in modeling the continuum, particularly when notable material properties differences exist in contiguous areas of the medium. In such cases, the mesh must be fine enough in such areas in order to obtain reliable results. Therefore, in this paper is advanced an algorithm to carry out automatic remeshing of local areas where the “remeshing” criteria is activated to refine the mesh accordingly. Herein the proposed algorithm integrated into a two dimensional finite element computer program is used to analyze a classical geotechnical problem to show the importance of locally refining the mesh and to demonstrate that regardless of the geometric characteristics of the initial mesh, the algorithm yields practically equal results. Computations with the proposed method are compared with the corresponding close form solutions, whenever available, to show the usefulness and reliability of the remeshing algorithm. Furthermore, to show the algorithm’s versality, the initial loading boundary conditions considered for the cases included in this paper are modified in order to show how the automatic local remeshing is capable of adapting the initial mesh configuration into a new one as a function of the new boundary conditions. As shown in the paper, the final resulting meshes for both load boundary conditions considered are appreciably dissimilar from each other, which leads to somehow different results.

An advanced exergy analysis based on the dysfunction and malfunction methodology for a combined cycle power plant: a Mexican case study
International Journal of Exergy
https://doi.org/10.1504/IJEX.2018.093902
R. Herrera ¹ , Federico Méndez Lavielle²
¹ Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Zaragoza
² Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Thermoeconomic diagnosis, exergy, cycle power, irreversibility
Abstract: The present work studies the irreversibilities and inefficiencies of a combined power plant. The analysis predicts the malfunction and dysfunction distributions for a typical system located in Mexico. The study was conducted by first performing the energy balances of the system using the first law of thermodynamics. The concept of exergetic unit cost was then used to calculate the corresponding exergy destruction of the plant. And finally, structural theory and symbolic thermoeconomic analysis for constructing the malfunction and dysfunction conditions of the plant, showing clearly that for the combined cycle the irreversibilities are basically increased through the dysfunctions. The previous analysis shows the following results: the total increment of the irreversibility for the present cycle is 19879.33 kW, which represents about 3.5% of the fuel exergy required taking into account data of design; and the subsystems with the greatest dysfunctions correspond to both gas compressors.