Artículos Publicados

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

Fuente: Scopus.

Artículos 2022

Distributed generation in low-voltage DC systems by wind energy in the Baja California Peninsula, Mexico
Rodolfo Farías Miranda1 , Nadia Maria Salgado Herrera2 , Osvaldo Rodríguez Hernández2 , Juan Ramón Rodríguez Rodríguez3 , Miguel Robels 2 , Dante Ruiz Robles4 , Vicente Venegas Rebollar1
1 Tecnológico Nacional de México, Campus Morelia
2 Universidad Nacional Autónoma de México, Instituto de Energías Renovables
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Nacional Autónoma de México, Escuela Nacional de Estudios Superiores Unidad Juriquilla

Keywords: Distributed renewable energy access, Low-voltage direct current, Wind energy conversion system, Dual active bridge, Small signal model, Real-time validation
Abstract: Mexico's national electric grid comprises ten regional systems, with one isolated in the south of the Baja California Peninsula. In addition, providing electricity access remains a challenge in the country. Therefore, distributed renewable energy solutions are relevant to satisfy the electricity demand and promote grid development. Distributed renewable energy access (DREA) based on a wind energy conversion system integrated into low-voltage direct current (LVDC) networks is presented. The DREA is analysed and simulated under wind speed conditions measured and recorded for one year at Baja California Sur. A representative variability is applied to five type-4 wind turbines based on wind speed turbulence intensity analysis. The generated power is transferred through a bidirectional dual active bridge converter, controlled by a novel small-signal model using a single closed-loop proportional-integral control, owing to its modularity, power density, and ability to transfer power from LVDC to high-voltage direct current. The effectiveness and robustness of the proposed DREA are assessed via a complete mathematical model, corroborated by the simulation results in MATLAB-Simulink®, and validated by experimental results using the real-time simulator Opal-RT Technologies® and laboratory prototyping. The results indicate a DC-link voltage compensation and integration of a power capacity of 150 kW in the LVDC networks with an efficiency of 94%.
The Risk Atlas of Mexico City, Mexico: a tool for decision-making and disaster prevention
Natural Hazards
David Alberto Novelo Casanova1 , Gerardo Suárez 1 , Enrique Cabral Cano1 , Enrique Antonio Fernández Torres1 , Óscar Arturo Fuentes Mariles2 , Emre Havazli 3 , Miguel A. Jaimes 2 , Erika D. López Espinoza4 , Ana Lillian Martín Del Pozzo1 , Wendy V. Morales Barrera5 , Hipólito L. Morales Rodríguez2 , Amiel Nieto Torres1 , Sergio R. Rodríguez Elizarrarás5 , Darío Solano Rojas6 , Víctor M. Velasco Herrera1
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 University of Miami, Rosenstiel School of Marine and Atmospheric Science
4 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
5 Universidad Nacional Autónoma de México, Instituto de Geología
6 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Mexico City, Hazard, Vulnerability, Risk, Risk Atlas, Disaster prevention, Mexico
Abstract: We present a Risk Atlas of Mexico City based on a Geographical Information System (RA-GIS). We identified the prevalent social risk to the more relevant hazards in Mexico City (CDMX): earthquakes, volcanic eruptions, floods, landslides, forest fires, and land subsidence. A total of 274 shape-file maps were generated in this project. Seismic hazard was estimated for return periods (RP) of 20, 125, 250, and 475 years. Three areas in central and northwestern CDMX were identified along the Younger Chichinautzin Monogenetic Volcanic Field with a high probability of forming a new volcano. Subsidence is concentrated to the east and southeast of CDMX, where subsidence rates are among the highest worldwide. Flooding events were estimated for RP of 2, 5, 10, 50, and 100 years, and most of them are concentrated in the central and northern sectors of the city. During the dry season (December–April), southern CDMX has very high probability of forest fire occurrence. There is high susceptibility of landslides on the west and southwest of the city. The goals of this RA-GIS are to provide a tool to the local and federal authorities and all organizations responsible for disaster prevention and mitigation to: (1) improve the knowledge of the potential physical and social impact of local hazards; (2) provide elements for disaster prevention, mitigation, preparedness, and response; (3) benefit decision-makers with robust risk data; (4) provide information for land-use planning; and (5) support further research to reduce the impact of disasters caused by natural phenomena.
Secured telemedicine of medical imaging based on dual robust watermarking
The Visual Computer
David Mata Mendoza1 , Manuel Cedillo Henández1 , Francisco Javier García Ugalde2 , Antonio Cedillo Hernández3 , Mariko Nakano Miyatake4 , Héctor Pérez Meana3
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación
4 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias

Keywords: Digital watermarking, Information security, DICOM imaging, Authentication, Detachment avoidance
Abstract: Medical information management has progressed in the last few years because of the advances in information technologies. Nowadays, it is possible to share medical images among specialists geographically distant to interpret, discuss, and get improved diagnostics. However, any alteration of transmitted image metadata may lead to issues related to information security, such as detachment and authentication. Detachment refers to link the data of an electronic patient record to an incorrect medical image, while authentication aims to identify the image source. These security problems are critical as they may cause the loss of sensitive data or wrong medical diagnoses. Digital watermarking is an emerging technique that faces these security problems as it allows to embed the metadata directly into the medical image. This paper proposes a hybrid and robust watermarking technique to prevent detachment and authenticate medical images. The quantization index modulation algorithm under dither modulation in conjunction with forwarding error correction is used to embed relevant metadata as a robust-imperceptible watermarking to avoid detachment. The visible-imperceptible watermarking paradigm, whose use is an innovation in medical images, is applied to insert a second watermark in the spatial domain to perform authentication. The experimental results show the contribution of the proposed scheme and its efficiency regarding robustness and imperceptibility.
Numerical-analytical solutions of the fractional point kinetic model with Caputo derivatives
Annals of Nuclear Energy
Marco A. Polo Labarrios1 , Francisco Antonio Godínez Rojano2 , Sergio Quezada García3
1 Universidad Iberoamericana, Departamento de Física y Matermáticas
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Reactor dynamics, Fractional neutron point kinetic equations, Anomalous diffusion exponent, Caputo fractional derivative, Laplace Transform method, Chebyshev polynomials
Abstract: Novel solutions to the fractional neutron point kinetic equations in terms of Caputo derivatives are obtained for three different cases: 1) constant reactivity; 2) cold startup process of a Pressurized Water Reactor; and 3) start-up of a nuclear reactor. Numerical-analytical solutions for the first and second cases are achieved via Laplace transform technique with Talbot's method for the numerical inversion of the transformed equations. Analytical solutions for the third case are constructed by a collocation method using Chebyshev polynomials. The solutions predict inertia effects observed as a growth in neutron density up to reaching a peak and then a gradual decrease followed by a series of oscillations until reaching a steady state. This behavior, on the one hand, is accentuated as the fractional order decreases, and on the other hand, it is reconciled with the fact that the propagation speed of the neutrons within the reactor is finite.
Power System Coherency Detection from Wide-Area Measurements by Typicality-Based Data Analysis
IEEE Transactions on Power Systems
Lucas Lugnani 1 , Mario Roberto Arrieta Paternina2 , Daniel Dotta 1 , Joe H. Chow 3 , Yilu Liu 4
1 University of Campinas, Department of Electrical Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Rensselaer Polytechnic Institute, Department of Electrical Computer and Systems Engineering
4 University of Tennessee, Department of Electrical Engineering

Keywords: Coherency, clustering, data-driven, WAMS, statistical typicality
Abstract: This paper presents a new data-driven methodology for power system coherency identification of generator and non-generator buses. This methodology is exclusively based on intrinsic statistical properties extracted directly from observations, without any prior assumption of the probability distribution function (PDF) for the data. The main advances of this proposal are: ( i ) gathering of statistical information from the data itself despite scenarios where the PDF may change (different inverter-based load and generation scenarios, load levels of the system, and changes in topology); and ( ii ) assignment of buses into coherent areas without any tuning of parameters, nor manually labeling of huge amounts of training data. This new method, called typicality-based data analysis (TDA), is applied to the correlation metric of the distance between dynamic responses of buses, either voltage angles or frequencies. Simulated signals from a benchmark power system with cases considering the presence of non-synchronous generation and islanding conditions, and real data associated with generation trips in the U.S. Eastern Interconnection are used to corroborate the methodology effectiveness.
A Novel GaN-Based Solid-State Circuit Breaker with Voltage Overshoot Suppression
IEEE Transactions on Industrial Electronics
Gabriel E. Mejía Ruiz1 , Mario Roberto Arrieta Paternina1 , Alejandro Zamora Méndez2 , Julio Cesar Rosas Caro3 , Guillermo Bolivar O.4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
3 Universidad Panamericana, Facultad de Ingeniería
4 Corporación Universitaria Minuto de Dios, Facultad de Ingeniería

Keywords: Gallium nitride FETs, overcurrent protection, short-circuit protection, solid-state circuit breaker, voltage overshoot suppression, snubber circuit
Abstract: This paper proposes a novel ultra-Fast self-powered bidirectional solid-state circuit breaker (SSCB) with voltage overshoot suppression that uses gallium nitride (GaN) switches with very low conduction losses. This SSCB can be used in low and medium AC/DC networks for both short-circuit protection and overcurrent protection. An exhaustive methodology for RCD snubber design applied to SSCBs is provided. A comprehensive review of the technical literature is presented exhibiting that the proposed SSCB reduces conduction losses and detection time in comparison with other similar SSCBs. The performance features of the proposed SSCB are verified through the functional tests that are carried out employing a hardware-implemented prototype. Experimental results confirm that our proposal is able to detect and process the short-circuit failure in 282ns; the authors have not found any faster results in the literature.
Modeling a multi-layered blockchain framework for digital services that governments can implement
Journal of Intelligent & Fuzzy Systems
Fernando Rebollar 1 , Rocío Aldeco Pérez2 , Marco A. Ramos 1
1 Universidad Autónoma del Estado de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: The general population increasingly uses digital services, meaning services which are delivered over the internet or an electronic network, and events such as pandemics have accelerated the need of using new digital services. Governments have also increased their number of digital services, however, these digital services still lack of sufficient information security, particularly integrity. Blockchain uses cryptographic techniques that allow decentralization and increase the integrity of the information it handles, but it still has disadvantages in terms of efficiency, making it incapable of implementing some digital services where a high rate of transactions are required. In order to increase its efficient, a multi-layer proposal based on blockchain is presented. It has four layers, where each layer specializes in a different type of information and uses properties of public blockchain and private blockchain. An statistical analysis is performed and the proposal is modeled showing that it maintains and even increases the integrity of the information while preserving the efficiency of transactions. Besides, the proposal can be flexible and adapt to different types of digital services. It also considers that voluntary nodes participate in the decentralization of information making it more secure, verifiable, transparent and reliable.
A System Identification-Based Modeling Framework of Bidirectional DC-DC Converters for Power Grids
Journal of Modern Power Systems and Clean Energy
Gabriel E. Mejía Ruiz1 , Mario Roberto Arrieta Paternina1 , Juan Ramón Rodríguez Rodríguez1 , Juan Manuel Ramírez Arredondo2 , Alejandro Zamora Méndez3 , Guillermo Bolivar O.4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
4 Corporación Universitaria Minuto de Dios, Facultad de Ingeniería

Keywords: Dual active bridge, eigensystem realization algorithm, generalized average model, power converters identification, power converter modeling
Abstract: This paper proposes a systematic identification framework founded on the eigensystem realization (ER) to precisely model electronic power converters. The proposed framework furnishes an energy-based optimal reduction method to precisely identify the power converters' dynamics from simulated or actual raw data measured at the converter's ports. This approach does not require any prior knowledge of the topology or converter internal parameters to derive the system modal information. The proposed method's accuracy and feasibility are exhaustively evaluated via simulations and practical tests on a software-simulated and hardware-implemented dual activebridge (DAB) converter under steady-state and transient conditions. After different comparisons against the Fourier series-based generalized average model, the switching model, and experimental measurements; the proposed method attains a root mean square error less than 1% concerning the actual raw data and a computational effort reduction of 8.6 times regarding the Fourier-based model.
An analytical Survey of Attack Scenario Parameters on the Techniques of Attack Mitigation in WSN
Wireless Personal Communications
Karen Ávila 1 , Paul Sanmartin 2 , Daladier Jabba Molinares1 , Javier Gómez 3
1 Universidad del Norte,
2 Universidad Simón Bolívar,
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Security, WSN, Attacks in wireless sensor networks, IoT, Sybil, Wormhole, Selective forwarding, Sinkhole
Abstract: Wireless sensor networks (WSN) were cataloged as one of the most important emerging technologies of the last century and are considered the basis of the Internet of Things paradigm. However, an undeniable disadvantage of WSN is that the resources available for these types of networks, such as processing capacity, memory, and battery, are usually in short supply. This limitation in resources implements security mechanisms a difficult task. This work reviews 93 recent proposals in which different solutions were formulated for the different attacks in WSN in the network layer; in total, 139 references were considered. According to the literature, these attacks are mainly Sybil, wormhole, sinkhole, and selective forwarding. The main goal of this contribution is to present the evaluation metrics used in the state of the art to mitigate the Sybil, wormhole, sinkhole, and selective forwarding attacks and show the network topologies used in each of these proposals.
Multivariable binary adaptive control using higher-order sliding modes applied to inertially stabilized platforms
European Journal of Control
Andrei Battistel 1 , Tiago Roux Oliveira1 , Víctor Hugo Pereira Rodrigues1 , Leonid Fridman Golredich2
1 State University of Rio de Janeiro, Department of Electronics and Telecommunication Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Binary model reference adaptive control, Higher-order sliding modes exact differentiators, Multiple-input and multiple-Output systems, Global stability-tracking, Inertially stabilized platforms
Abstract: This paper presents an extension of the Binary Model Reference Adaptive Control (BMRAC) for uncertain multivariable (square) systems with non-uniform arbitrary relative degrees using only output feedback and its application to inertially stabilized platforms using a two degree of freedom gimbal as actuator. The BMRAC is a robust adaptive strategy with good transient performance, thus useful for uncertain systems, and the multivariable framework is suitable to deal with mechanical unbalances. Using a newly proposed differentiator with dynamic gains based on higher-order sliding mode, the proposed controller achieves global and exact tracking. To illustrate the effective of the proposed solution, simulations are presented using real-word data obtained from an instrumented vehicle in an irregular ground.
Continuous Sliding-Mode Output-Feedback Control for Stabilization of a Class of Underactuated Systems
IEEE Transactions on Automatic Control
Luis Ovalle 1 , Héctor Ríos 1 , Miguel Llama 1 , Leonid Fridman Golredich2
1 Instituto Tecnológico de la Laguna, División de Estudios de Posgrado e Investigación
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Underactuated Systems, Output-Feedback Stabilization, Sliding-Mode control
Abstract: This paper presents a robust output-feedback control scheme for the stabilization of a class of non-linear underactuated mechanical systems in presence of coupled disturbances. The scheme is based on the so-called coupled sliding-mode control, i.e., no transformation into the normal form is required. The proposed output approach is composed of a Super-Twisting Controller and a High-Order Sliding-Mode Observer that robustly stabilize the origin of the system asymptotically. All of the results are proven by Lyapunov approaches. The proposed approach is validated by means of simulations and experimental results on a 4 degrees of freedom (DOF) underactuated crane.
Conditions of self-oscillations in generalized Persidskii systems
IEEE Transactions on Automatic Control
Jian Wang 1 , Jesús Mendoza Avila2 , Denis Efimov 3 , Alexander Aleksandrov 4 , Leonid Fridman Golredich2
1 Hangzhou Dianzi University, School of Automation
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Villenueve d'Ascq, Nord Europe Center
4 St. Petersburg State University, Faculty of Applied Mathematics

Keywords: Lyapunov methods, Oscillators, Stability analysis, Nonlinear dynamical systems, Trajectory, Robustness, Sliding mode control
Abstract: For a class of generalized Persidskii systems, whose dynamics are described by superposition of a linear part with multiple sector nonlinearities and exogenous perturbations, the conditions of practical stability, instability and oscillatory behavior in the sense of Yakubovich are established. For this purpose the conditions of local instability at the origin and global boundedness of solutions (practical input-to-state stability) are developed in the form of linear matrix inequalities. The proposed theory is applied to investigate robustness to unmodeled dynamics of nonlinear feedback controls in linear systems, and to determine the presence of oscillations in the models of neurons.
Adaptive sliding mode control with guaranteed performance based on monitoring and barrier functions
International Journal of Adaptive Control and Signal Processing
Víctor Hugo Pereira Rodrigues1 , Liu Hsu 1 , Tiago Roux Oliveira2 , Leonid Fridman Golredich3
1 Federal University of Rio de Janeir, Department of Electrical Engineering
2 State University of Rio de Janeiro, Department of Electronics and Telecommunication Engineering
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: barrier function, monitoring function, norm observer and global tracking, output feedback, slidingmode control
Abstract: This paper proposes a new adaptive sliding mode control approach via output feedback for a class of nonlinear systems. The sliding-mode based controller can deal with parametric uncertainties and (un)matched disturbances with unknown upper bounds. Finite-time convergence of the tracking error to a predefined neighborhood of the origin of the closed-loop system is proved with guaranteed transient and steady-state performance. Basically, the novelty of our result lies on combining two important adaptation tools: monitoring and barrier functions. The adaptation process is divided into two stages, where an appropriate monitoring function allows for the specification of performance criteria during the transient phase, while the barrier function ultimately confines the tracking error within a small residual set in steady state. Simulation results including an application to Anti-lock Braking System illustrate the advantages of the proposed adaptive control strategy.
Unit commitment for multi-terminal VSC-connected AC systems including BESS facilities with energy time-shifting strategy
International Journal of Electrical Power & Energy Systems
Juan S. Guzmán Feria1 , Luis Miguel Castro González1 , José Horacio Tovar Hernández2 , Néstor González Cabrera1 , Guillermo Gutiérrez Alcaraz2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico de Morelia, Posgrado en Ingeniería Eléctrica

Keywords: AC/DC networks, Battery energy storage systems, Mixed-integer linear programming, Shift factors, Unit commitment, VSC stations
Abstract: This paper proposes a novel modelling framework for Unit Commitment (UC) studies in multi-terminal VSC-connected AC grids. Battery Energy Storage Systems (BESS) are also considered with an energy time-shifting strategy whose charge and discharge modes are defined within the 24-hour planning horizon to promote a high competition level of energy trading in the power grid. The entire transmission network is formulated by shift factors and power losses of AC/DC branches and VSC units are included by piecewise linear functions. Thus, this novel UC approach retains a mixed-integer linear programming model with a high modelling versatility for arbitrary hybrid power grids accommodating any number of VSC stations and BESS units. The method described in this paper enables the optimal generation scheduling combined with the charge and discharge BESS modes. Its applicability is confirmed using two case studies, one featuring a four-terminal VSC-HVDC system with two BESS, and another characterised by seven VSC-connected AC systems with five BESS. To validate the proposed method, results are compared against those furnished by the classic UC representing the network through nodal equations. It is concluded that both methods favourably agree with each other as the errors are inferior to 2%. The usefulness of the proposed method to the real-time operation of AC/DC grids with BESS facilities is valuable.
Decentralized robust state estimation of multimachine power systems
International Journal of Electrical Power & Energy Systems
Natanael Vieyra Valencia1 , Jesús Álvarez 2 , Paul Rolando Maya Ortíz3
1 Universidad Nacional Autónoma de México, Posgrado en Ingeniería Eléctrica
2 Universidad Autónoma Metropolitana, Departamento de Procesos e Hidráulica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Decentralized dynamic state estimation, Multimachine power system, Nonlinear interconnected system, Geometric estimator, Extended kalman filter, Synchronous generator
Abstract: The problem of online estimating the states of nonlinear (NL) Multimachine Power Systems (MPSs) is addressed within a constructive framework that combines notions and tools from electrical engineering and nonlinear estimation theory. First, the standard NL centralized model is realized as a set of linear decentralized robustly observable models, with augmented states that capture nonlinearity, parameter error, and intermachine state interaction. Then, based on the observability property of the decentralized model, a robustly convergent linear Geometric (Luenberger-like with integral action) estimator with simple tuning is constructed. With respect to previous MPS estimation techniques, the novelties are: (i) from a theoretical perspective, the comprehensiveness of the methodology, with model design, solvability in terms of observability, and robust functioning criteria coupled with a simple tuning scheme, and (ii) from an industrial applicability viewpoint, an online computation load considerably smaller than the one of the NL Extended Kalman Filter (EKF), and a tuning scheme appreciably simpler than the one of the NL sliding mode perturbation observer (SMPO). The proposed design methodology is illustrated through numerical simulation with a representative case example.
Doubly conjugate asymptotic analysis for the temperature and electric fields in a combined gel and stratum corneum system
International Journal of Thermal Sciences
Edgar Ali Ramos Gómez1 , 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: Skin electroporation, Joule heating effect, Conjugate double problem, Theoretical predictions
Abstract: In the present work, we study with the aid of regular perturbation techniques under what physical conditions, the thermal and electrical simultaneous interactions that occur between a gel and a stratum corneum of the skin, can operate in direct contact to avoid possible damage to the human skin. This doubly conjugate asymptotic analysis was formulated in terms of a pair of dimensionless conservation equations for the energy and electrical charge in each medium and it was solved by using asymptotic perturbation techniques, identifying a dimensionless parameter, denoted as , that measures the competition of electrical conductivities in the two medium affected by the electrical pulse. Because the electrical conductivity of the stratum corneum is very small, this parameter assumes usually very large values compared with unity and the theoretical predictions show the relevance that this parameter has on the increment of the temperature in both media. Therefore, we consider that this parameter can guide a positive performance of this class of medical treatments based on electric signals because delimits, under transient conditions, up to where the simultaneous presence of thermal and electrical effects control the reversible skin electroporation. The asymptotic analysis was validated with experimental data of other authors and a numerical solution of the full governing equations.
Large diurnal wind variability over the western and northern Campeche Bank caused by the low latitude of the Yucatan Peninsula and its interaction with Easterlies
Atmospheric Research
María Eugenia Allende Arandía1 , Jorge Zavala Hidalgo2 , Rosario Romero Centeno2 , Gemma L. Franklin 1 , Nidia Taylor Espinosa2 , María Elena Osorio Tai3
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ciencias de la Atmósfera y Cambio Climático
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Large wind variability, Easterlies, Diurnal signal, Campeche Bank, Breeze extension, Breeze circulation cell
Abstract: The northern and western Campeche Bank have an intense diurnal cycle with a significant offshore extension. Wind observations along the coast of the southern Gulf of Mexico, confirm that the breeze phenomenon occurs with great intensity and extension. To analyze this mesoscale phenomenon, a numerical simulation of high spatial-temporal resolution was performed using the Weather Research and Forecasting model (WRF). Diurnal wind components were fitted to a sinusoidal function, and the resulting parameters were used to obtain monthly elliptical hodographs. The greatest amplitude of the diurnal signal occurred in April, at the cays and islands, whereas in the continental region the amplitude of the diurnal component was greatest on the northern and western coasts of the Yucatan Peninsula. The large amplitude of this diurnal wind component is determined by a combination of different factors: the latitude, the geographical configuration of the southern Gulf of Mexico, the orography, the dominant easterly winds, and the development of an intense thermal contrast. Regarding the analysis of the wind components, a strong asymmetry was found between the sea-breeze and the land-breeze. Sea breeze winds are intense over the ocean, exceeding 10 ms-1 at 100 km from the coastline. The friction effect over land is also perceptible, reducing the wind magnitude by more than 6 ms-1. The formation of a breeze cell circulation with opposing easterly winds creates a strong convergence zone. It was found that the Yucatan Peninsula location, due to its relatively low latitude and altitude, in combination with the predominant easterly winds, favors these dynamics.
Numerical simulation data and FORTRAN code to compare the stress response of two transversely isotropic hyperelastic models in ABAQUS
Data in Brief
Carlos Castillo Méndez1 , Armando Ortiz Prado1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Finite element, UMAT subroutine, Hyperelasticity, Anisotropic invariants
Abstract: We present the numerical simulation data obtained by implementing a user material subroutine (UMAT) in the finite element commercial package ABAQUS. The simulation data correspond to the stress response of two transversely isotropic hyperelastic models on homogeneous and non-homogeneous deformations. First model is proposed in the co-submitted article [1] and depends on both anisotropic invariants ( and ) to describe the fiber reinforcement. The second model is the Holzapfel-Gaser-Ogden (HGO) model described in [2], that only depends on the anisotropic invariant . Since the first model is not found in the ABAQUS material library, we present a FORTRAN code for a UMAT subroutine. In addition, we introduce in detail the steps to implement the material models using the attached files in ABAQUS.
Determination of optimal electrochemical parameters to reproduce copper artistic patina on quaternary alloys
Materials Letters
Jesús Rafael González Parra1 , Alba Covelo Villar1 , Miguel Ángel Hernández Gallegos1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Patina, Electrochemical impedance spectroscopy, Bronze, Corrosion, Surfaces
Abstract: A copper patina provides both a pleasing aesthetical appearance and corrosion protection to artistic artworks so the electrochemical features for restoring metallic artifacts need to be studied. In this study, the potentiodynamic scan rate consisting of 0.5, 1, 3, 5, 7 10 mV/s to develop artistic patinas on a quaternary copper alloy was studied. The results obtained by SEM/EDS indicate that the patina on the surface is a porous layer mainly composed of copper/chloride corrosion products. The X-Ray analysis identified the formation of nantokites and atacamites depending on the scan rate that was applied. The morphology appearance shows a greenish patina and a more porous structure for scan rates lower than 5 mV/s. Polarization curves and electrochemical impedance spectroscopy determined that the corrosion protection increases at lower scan rates due to higher barrier properties of the patina layer.
An asymptotic and algebraic estimation method of harmonics
Electric Power Systems Research
Francisco Beltrán Carbajal1 , Rubén Tapia Olvera2 , Antonio Valderrabano González3 , Hugo Yáñez Badillo4
1 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Panamericana, Facultad de Ingeniería
4 Tecnológico de Estudios Superiores de Tianguistenco, Departamento de Investigación

Keywords: Harmonic distortion, Harmonic estimation, On-line parameter estimation, Algebraic identification
Abstract: A new on-line and time-domain parameter estimation approach of harmonics in electric power system signals is introduced. The developed parametrical identification perspective is based on asymptotic and algebraic estimation techniques, and vibrating signal modeling. Specified harmonics and DC offset component of some measured distorted oscillating signal are reconstructed asymptotically. In this fashion, closed-form explicit formulae to compute into a small window of time, algebraically, on-line and in time-domain, the parameters of amplitude, frequency and phase of harmonics are then derived. Analytical, numerical and experimental results of six and twelve pulses converter reveal the effectiveness and efficiency of the proposed selective estimation approach for harmonics and corresponding parameters of measured oscillating electric signals into an operating frequency bandwidth. Among others, synchronization of power converters or switches to grid without the use of filtering can be achieved with this strategy.
Thermodiffusive effect on the local Debye-length in an electroosmotic flow of a viscoelastic fluid in a slit microchannel
International Journal of Heat and Mass Transfer
A. Hernández 1 , José Carlos Arcos Hernández1 , J. Martínez Trinidad1 , Oscar Eladio Bautista Godínez1 , Salvador Sánchez 2 , Federico Méndez Lavielle3
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Local Debye-length, Thermodiffusion, Viscoelastic fluid, Electroosmotic flow, Soret effect
Abstract: This work theoretically studies the influence of the thermodiffusive effect on the local Debye length thickness in a purely electroosmotic flow in a parallel flat plate microchannel. An imposed electric field between the ends of the microchannel interacts with an ionized viscoelastic fluid causing Joule heating, which induces a temperature gradients along the microchannel, affecting the fluid’s physical properties, and in a notable manner, the ionic distribution into the electric double layer (EDL), resulting in thermodiffusion. Consequently, an induced pressure field counterbalances the axial variation of the plug-like electroosmotic velocity to maintain the fluid mass continuity. Also, the ionic distribution and electrical potential based on the non-isothermal Poisson-Boltzmann equation are modified. To estimate the local Debye length thickness, the coupled set of the Poisson-Boltzmann, momentum, and energy equations are solved numerically in the limit of the lubrication approximation theory (LAT). Our results indicate that the thermodiffusion has an important effect on the thickness of the local Debye-length, particularly in the warm zone of the fluid. Besides, the ionic response to thermal fields is given by a positive Soret coefficient, which indicates that the ionic particles move from warm to cold regions in the fluid, giving place to a thinner Debye length and lower ionic concentration around the warming zone; this migration of ions confirms that the dimensionless mass-flow rate is affected with the Soret coefficient compared with the non-thermodiffusion case.
Neutronic and thermohydraulic analysis of a SMR-PWR core with TRISO fuel based on a 2n multifactorial analysis
Nuclear Engineering and Design
Jesús Rosales 1 , Juan Luis François Lacouture1 , Annie Ortiz 2 , Carlos García 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de La Habana, Insituto Superior de Tecnologías y Ciencias Aplicadas

Keywords: SMR, TRISO, Packing fraction, Serpent, Ansys CFX
Abstract: The study of small modular reactors has generated increasing interest in recent years in the international scientific community. Their applications and versatility make them an attractive option among candidates considered in generation III+ and IV. Additionally, the modeling and study of TRISO fuel in PWR-type modular reactors constitutes a challenge and opens new possibilities for its use. In this work, new studies are carried out on the conceptual design of SMR with TRISO fuel. Through a multifactorial statistical analysis, the influence of the enrichment, the packing fraction, and the kernel size on the multiplicative properties of the TRISO fuel is quantitatively evaluated. Once done, a core configuration is established with the aim that it can remain critical for approximately four years, without the need of refueling. Based on two models, one neutronic in Serpent and one thermohydraulic in Ansys CFX, the performance of the designed reactor is studied, and the results obtained when using a packing matrix composed of graphite and other composed of SiC are compared. To carry out this simulation, power correlations as a function of the height of the fuel assembly and temperature-dependent correlations are obtained for the fuel zone that is composed of the TRISO particles dispersed in the packing matrices. Temperature distributions in the fuel, clad, gap and coolant for the critical assembly were obtained.
Role of anisotropic invariants in numerically modeling soft biological tissues as transversely isotropic hyperelastic materials: A comparative study
International Journal of Non-Linear Mechanics
Carlos Castillo Méndez1 , Armando Ortiz Prado1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Anisotropic invariants, Soft tissues, Hyperelasticity, Transversely isotropic, Finite element
Abstract: Fiber-reinforced biological soft tissues are often modeled as anisotropic hyperelastic materials. Four strain invariants can be used to define a strain energy function for soft tissues reinforced with a single fiber family: two isotropic invariants and two anisotropic invariants . Invariant is often omitted in the strain energy functions to simplify the problem mathematically. In this study, the implications of using only or the use of both anisotropic invariants in the numerical modeling of soft tissues were analyzed. A simple modification to the Holzapfel–Gasser–Ogden (HGO) model is proposed by adding a term that contains invariant . Material parameters were calculated by fitting the models with experimental data of uniaxial traction in the tibialis anterior tendon tissue of rats. General analytical solutions for the simple load scenarios were obtained. Such solutions are taken as a reference point to measure the precision of the numerical results obtained in the finite element simulations. The main differences between the models were observed in the shear behavior. The proposed model predicts three different shear responses (two responses with fiber reinforcement and one isotropic response), while the HGO model predicts two equal isotropic responses and only one with fiber reinforcement. Two sets of simple shear experimental data on a fiber-reinforced elastomer material were used to verify the shear stress prediction of the models. The experimental data show that the three shear behaviors are different; thus, the HGO model offers a limited description of the shear behavior. Furthermore, analytical solutions and experimental data suggest that invariant is related to the elastic energy of the fibers when the material is subjected to shear in a direction parallel to the fibers. The models for non-homogeneous deformations were also compared. For this comparison, an irregular geometry was implemented in ABAQUS, and the traction and shear conditions were simulated by changing the fiber inclination. The most critical difference was found when the shear was parallel to the direction of the fiber and the minor difference when the fiber was at 45° to the load force.
Gamma-ray flux measurement and geotechnical studies at the selected site for the LABChico underground laboratory
The European Physical Journal Plus
Alexis Aguilar Arevalo1 , Xavier Bertou 2 , Carlos Canet Miquel3 , Miguel Angel Cruz Pérez4 , Alexander Deisting 5 , Adriana Dias 5 , Juan Carlos D' Olivo 1 , Francisco Favela Pérez1 , Estela A. Garcés 6 , E. González García7 , Adiv González Muñoz6 , Jaime Octavio Guerra Pulido7 , Javier Mancera Alejandrez7 , Daniel José Marín Lámbarri6 , A. M. Martínez Mendoza6 , Mauricio Martínez Montero1 , Jocelyn Monroe 5 , Sean Paling 8 , Simon Peeters 9 , Paul Scovell 8 , Cenk Türkoglu 9 , I. G. Vallejo Castillo7 , Eric Vázquez Jáuregui6 , Joseph Walding 5
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares
2 Centro Atómico Bariloche,
3 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
4 Universidad Nacional Autónoma de México, Programa de Posgrado en Ciencias de la Tierra
5 University of London, Royal Holloway
6 Universidad Nacional Autónoma de México, Instituto de Física
7 Universidad Nacional Autónoma de México, Facultad de Ingeniería
8 Boulby Mine, Boulby Underground Laboratory
9 University of Sussex, Department of Physics and Astronomy

Abstract: The ?-ray flux inside La Quaalude mine, the selected site for the construction of the underground laboratory LABChico in Mexico, is reported for energies below 3 MeV. Data were recorded with a 0.669 kg thallium-activated sodium iodide (NaI) crystal detector deployed for 3.6 hr. The detector response was calculated via Monte Carlo simulations with GEANT4 and validated against point-like calibration sources, and the ?-ray spectrum was extracted using an unfolding technique. The ?-ray flux above 250 keV and below 3 MeV is 0.1768 ?/cm2/s. The two most intense ?-rays in the natural radioactive background, 40K and 208Tl, were identified. The flux measured for these isotopes is 0.0363 ± 0.0020 ?/cm2/s and 0.0016 ± 0.0005 ?/cm2/s, respectively. A ?-ray spectrometry analysis of rock samples showed 674.0 ± 2.0 Bq/kg, 24.0 ± 0.1 Bq/kg, and 17.7 ± 0.2 Bq/kg, of 40K, 232Th, and 238U, respectively. These results are compared with deep underground facilities such as SURF, SNOLAB, Boulby, Modane, and Gran Sasso, with differences observed mainly due to the rock composition. Geotechnical studies of the mine and its rock composition are also reported.
Electroosmotic flow in a thin microchannel under the influence of some thermal electrokinetic effects
Journal of the Brazilian Society of Mechanical Sciences and Engineering
Edgar Ali Ramos Gómez1 , César Treviño 2 , Federico Méndez Lavielle1 , José Joaquín Lizardi Del Ángel3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ciencias
3 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: Electrokinetics effects, Joule heating, Variable properties
Abstract: In this work, we predict for a laminar electroosmotic flow in a thin microchannel, the impact that has some non-isothermal electrokinetics effects when the Debye length and the fluid viscosity are both temperature-dependent functions. The motion of the electroosmotic flow is caused with the aid of an external and uniform electric field. The presence of this electric source over the fluid pattern translates into continuous action of the Joule heating, causing a non-isothermal electroosmotic flow. The influence of the above non-isothermal effects conducts to include important temperature gradients in the momentum equations such that induced pressure gradients along the microchannel are established which in turn changes drastically the velocity field. Relevant variables such as the dimensionless volumetric flow rate show different values in comparison with the purely isothermal electroosmotic flow.
Risk assessment of land subsidence and associated faulting in Mexico City using InSAR
Natural Hazards
Enrique Antonio Fernández Torres1 , Enrique Cabral Cano1 , David Alberto Novelo Casanova1 , Darío Solano Rojas2 , Emre Havazli 3 , Luis Salazar Tlaczani1
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 California Institute of Technology, Jet Propulsion Laboratory

Keywords: Land subsidence, InSAR, Risk assessment, Socioeconomic vulnerability, Surface faults, México
Abstract: Land subsidence and associated faulting have affected Mexico City (CDMX), Mexico, for more than 100 years. However, despite the extensive research on land subsidence in CDMX, very few investigations focus on characterizing its socioeconomic risk due to land subsidence. In this article, we present Mexico City’s socioeconomic risk map due to land subsidence and associated faulting, combining our data from a land subsidence characterization based on InSAR processing with a socioeconomic vulnerability assessment. Our results show two high subsidence velocity areas. The largest area is located in the northeast sector of CDMX and the neighboring State of Mexico suburbs, where the maximum subsidence rate reaches up to 423 mm/year. We also found that 40.4% of the total cumulative length of land subsidence-associated faults correspond to high 15.6% and very high 24.8% classes of subsidence horizontal gradient. Our results demonstrate a spatial correlation between areas of high subsidence rate and horizontal gradient with high and very high socioeconomic vulnerability zones. Under this scenario, 9% of the urbanized areas, about 70.7 km2, are exposed to high and very high land subsidence socioeconomic risk where approximately 12.6% of the CDMX population lives.
Arsenic and lead in the soils of San Antonio–El Triunfo mining district, B.C.S., México: a human health risk assessment
Environmental Earth Sciences
Ernesto Hernández Mendiola1 , Francisco Martín Romero1 , Diana Meza Figueroa2 , Griselda Berenice Hernández Cruz3 , L. Gerardo Martínez Jardines1 , Violeta Espino Ortega3
1 Universidad Nacional Autónoma de México, Instituto de Geología
2 Universidad Nacional Autónoma de México, Laboratorio Nacional de Geoquímica y Mineralogía
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bioaccessibility, Geoavailability, Solid particles, Fine soil fraction, Carcinogenic and non-carcinogenic risks, Arsenic, Lead
Abstract: The MD SA-ET in Baja California Sur, Mexico, had over 200  years of intermittent mining activities. Studies in the area have reported Pb, Cd, Zn, and As dispersion from waste to soils, sediments, and groundwater, suggesting that even after all this time, biogeochemical processes have not completely mitigated the risk. Furthermore, evaluating how the fine particles in soils could control the human health risk by geochemical and mineralogical mechanisms has not yet been initiated. This study discusses the geoavailability and bioaccessibility based on the environmental and human health risks in an arid environment where the population is currently exposed to abandoned mining waste. The results show that urban soils (US) and stream sediments (SS) have very high total concentrations of As and Pb, but with low geoavailability, suggesting low environmental risk. Despite this, bioaccessibilities up to 100% were observed for As and Pb in the US, suggesting high risks for the inhabitants of San Antonio and El Triunfo towns. The blood Pb levels and the carcinogenic risk for As exposure assessed here show maximum values of 115.77 µgPb  dL-1 and 85 × 10–4, respectively, which exceed the recommended limits according to USEPA. Chemical identification of microparticles (< 250  µm) by SEM–EDS shows bright metal solids with high iron content, commonly interpreted as iron oxide. However, it was possible to identify microparticles (< 5  µm) rich in Fe associated with ultrafine particles (< 1  µm) with high Pb and As contents. We conclude that differences between the geoavailability and bioaccessibility for soils and sediments in this study indicate that the solid microphases (possible Fe-oxides and oxyhydroxides) present in the fine soil fraction from MD SA-ET may control the geoavailability and bioavailability of As and Pb, as well as the environmental and human health risks.
Remote sensing-aided rainfall–runoff modeling in the tropics of Costa Rica
Hydrology and Earth System Sciences
Saúl Arciniega Esparza1 , Christian Birkel 2 , Andrés Chavarría Palma2 , Berit Arheimer 3 , José Agustín Breña Naranjo4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 University of Costa Rica, Department of Geography and Water and Global Change Observatory
3 Swedish Meteorological and Hydrological Institute,
4 Comisión Nacional del Agua, Instituto Mexicano de Tecnología del Agua

Abstract: Streamflow simulation across the tropics is limited by the lack of data to calibrate and validate large-scale hydrological models. Here, we applied the process-based, conceptual HYPE (Hydrological Predictions for the Environment) model to quantitatively assess Costa Rica's water resources at a national scale. Data scarcity was compensated for by using adjusted global topography and remotely sensed climate products to force, calibrate, and independently evaluate the model. We used a global temperature product and bias-corrected precipitation from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) as model forcings. Daily streamflow from 13 gauges for the period 1990–2003 and monthly Moderate Resolution Imaging Spectroradiometer (MODIS) potential evapotranspiration (PET) and actual evapotranspiration (AET) for the period 2000–2014 were used to calibrate and evaluate the model applying four different model configurations (M1, M2, M3, M4). The calibration consisted of step-wise parameter constraints preserving the best parameter sets from previous simulations in an attempt to balance the variable data availability and time periods. The model configurations were independently evaluated using hydrological signatures such as the baseflow index, runoff coefficient, and aridity index, among others. Results suggested that a two-step calibration using monthly and daily streamflow (M2) was a better option than calibrating only with daily streamflow (M1), with similar mean Kling–Gupta efficiency (KGE ~ 0.53) for daily streamflow time series, but with improvements to reproduce the flow duration curves, with a median root mean squared error (RMSE) of 0.42 for M2 and a median RMSE of 1.15 for M1. Additionally, including AET (M3 and M4) in the calibration statistically improved the simulated water balance and better matched hydrological signatures, with a mean KGE of 0.49 for KGE in M3–M4, in comparison to M1–M2 with mean KGE < 0.3. Furthermore, Kruskal–Wallis and Mann–Whitney statistical tests support a similar model performance for M3 and M4, suggesting that monthly PET-AET and daily streamflow (M3) represents an appropriate calibration sequence for regional modeling. Such a large-scale hydrological model has the potential to be used operationally across the humid tropics informing decision-making at relatively high spatial and temporal resolution.
Flow patterns of multiple axial-radial impellers for potential use in aerated stirred tanks
Chemical Engineering & Technology
David Posadas Navarro1 , Carlos Alberto Palacios Morales2 , Abel Blancas Cabrera3 , Mauricio A. Trujillo Roldán4 , Martín Salinas Vázquez4 , Gabriel Ascanio 1
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomédicas
4 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Aerated stirred tank, axial-radial impeller, flow fields, fluid mechanics, PIV
Abstract: The hydrodynamics of a stirred tank equipped with multiple hybrid impellers (ARIs) has been experimentally characterized. They were coaxially placed to agitate a viscous Newtonian fluid under gassed conditions. Experiments were performed using the particle image velocimetry technique (PIV) and flow fields were reported in terms of the velocity magnitude, vertical currents, turbulent intensity, and strain rates. For comparison purposes, impellers providing radial flow (Rushton turbines) and axial flow (pitched blade turbines) were also tested. Results show that hybrid impellers provided a uniform flow distribution throughout the tank at moderate strain rates, which make them an attractive alternative for fermentation processes with shear-sensitive cultures and viscous liquids.
A Hamiltonian control approach for electric microgrids with dynamic power flow solution
Sofía Ávila Becerril1 , Gerardo Espinosa Pérez1 , Juan E. Machado 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 University of Groningen, Faculty of Science and Engineering

Keywords: Microgrid control, Passivity-based control, Hamiltonian systems
Abstract: In this paper, a control scheme for islanded electric microgrids is proposed. Exhibiting a dynamical structure and based on passivity, cascaded systems, and input-to-state stability arguments, the asymptotic stability properties of the closed-loop system are formally established to guarantee that voltage regulation and a power network balance are achieved. In contrast to other approaches, the controller design considers the differential–algebraic structure of the system obtained by the explicit inclusion of the network’s dynamic, the existence of both a grid-forming and grid-following nodes, and the highly nonlinear structure of the power balance equations.
Implications of unconventional oil and gas development on groundwater resources
Current Opinion in Environmental Science & Health
Saúl Arciniega Esparza1 , Antonio Hernández Espriú1 , Michael Young 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 The University of Texas at Austin, Jackson School of Geosciences

Keywords: Shale gas, Hydraulic fracturing, Groundwater, Water stress
Abstract: An intensification of water use per well for hydraulic fracturing (HF) has been observed in different regions of the U.S. during the last 20 years. Water-scarce regions undergoing the most intensive unconventional reservoir development also face water and wastewater management issues to support HF activities. In this review, we analyze the current state of water use related to HF, focusing on the implications of shale gas development on groundwater resources within water-limited regions in the U.S. Recent concerns of HF water management highlight the importance of wastewater treatment and reuse to decrease the dependence on freshwater sources and to minimize the hazards of wastewater disposal.
Non-isothermal effects in the slippage condition and absolute viscosity for an electroosmotic flow
European Journal of Mechanics - B/Fluids
Edgar Ali Ramos Gómez1 , César Treviño 2 , José Joaquín Lizardi Del Ángel3 , Federico Méndez Lavielle1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ciencias
3 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: Electroosmotic flow, Joule effect, Non-isothermal effects, Slip condition
Abstract: In this work, we have developed a novel asymptotic analysis using perturbation techniques for an electroosmotic flow in a rectangular microchannel, considering that the absolute viscosity is a function of temperature; a situation that affects also the slip condition at the walls of the microchannel, . The physical importance of this temperature dependence is based on the presence of the applied external electric field on the electrolyte solution, which originates the Joule heating effect that disturbances the isothermal hydrodynamic behavior. The above leads to a significant increase of the volumetric flow rate for this non-isothermal condition in comparison to the purely isothermal electroosmotic flow. This result is simultaneously controlled by the heat losses to the ambient and the slip effect: the lower the presence of the heat dissipation mechanism on the outer walls of the microchannel and the higher the sliding condition, the higher the values of the volumetric flow rate. The above trend differs substantially from the isothermal case and finds its justification in the recognition of the presence of the Joule heating effect that induces significant longitudinal and transverse temperature gradients along the microchannel. Considering the proper limitations of the asymptotic analysis, we compare the present asymptotic results with a full numerical solution of the governing equations, which are composed of the continuity, momentum, and energy equations for the electrolyte flow, together with the Poisson–Boltzmann.
A new telesurgery generation supported by 5G technology: benefits and future trends
Procedia Computer Science
Emmanuel Mendoza Navarro1 , Adrielly Nahomee Ramos Álvarez1 , Francisca Irene Soler Anguiano1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Telesurgery, 5G, Robotic System
Abstract: Telesurgery is a medical practice that has been developed for the last two decades. The idea is very simple, a highly trained surgeon performs a surgical intervention on a patient while being away from the operating room. The surgery execution is done through two principal equipment: a robotic one installed in the operating room and a remote station from which the surgeon controls the robot. The communication between both parties is established through a specialized internet connection. The research and development of these remote surgery systems have been revolutionizing the medicine praxis due to its multiple benefits. During the last years, these systems have substantially improved many of their main limiting aspects, furthermore, the incorporation of 5G technology is a booster in telesurgery possibilities. Nonetheless, telesurgery benefits are not available for everyone because telesurgery requires high-cost equipment incorporation, specialized facilities and staff. This is the main reason for which health systems in developing countries dismiss its application. As a result, this paper explains telesurgery with a brief historical review and future trends of this technology and also presents a value proposition that may facilitate telesurgery practice in remote medical units. Focusing on the implementations and benefits that 5G technology can provide to the development of telesurgery as a development opportunity medical praxis linked to the accelerated growth of high-speed networks in the connected world.
Cognitive evaluation of capital structure: Effect of cognitive factors on the debt ratio in Mexican construction industry
Contaduría y Administración
José Anselmo Pérez Reyes1 , Ananya Rajagopal 2 , Montserrat Reyna Miranda2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Anáhuac, Facultad de Economía y Negocios

Keywords: capital structure, cognitive finance, cost of capital, debt ratio, decision-making process, leverage
Abstract: This study analyzes the impact of the construct of the capital structure on the observed debt ratio of an organization, in terms of the new approach of Cognitive Finance (Pérez et al, 2019) within the construction industry in Mexico. Using exploratory factor analysis and structural equation model (SEM), latent variables of capital structure from the responses to an instrument applied to 154 CFOs of construction companies in Mexico. Then a non-parametric correlation test is performed, to measure the impact of each latent variable on the observed debt-to-equity ratio. The study finds that concerns about the political environment, the trust from clients and suppliers, among other variables, have an impact in the decision-making process of construction CFOs related to the debt-to-equity ratio, in addition to those variables stablished by Traditional Financial Theory. The results suggest that unobservable variables must be considered to gain a deeper understanding of the decision-making process and that an integral vision to consider the study of the motivations that are behind of the observable financial behavior is necessary.
Physical and chemical evolution of the largest monogenetic lava field in the Central Andes: El Negrillar Volcanic Field, Chile
Journal of Volcanology and Geothermal Research
Daniela Parra Encalada1 , Patricia Larrea 1 , Camila Loaiza 1 , Rubén Cartagena 1 , Sergio Salinas 2 , Benigno Godoy 1 , Pablo Grosse 3 , Petrus Le Roux 4
1 Universidad de Chile, Facultad de Ciencias Físicas y Matemáticas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Fundación Miguel Lilo,
4 University of Cape Town, Department of Geological Sciences

Keywords: Mafic to intermediate volcanism, Paleoreconstruction, Volumetric rates, Morphometric and rheological calculations, Altiplano-Puna plateau, Central Volcanic Zone
Abstract: El Negrillar volcanic field is one of the most voluminous monogenetic volcanic fields so far identified in the Central Volcanic Zone (CVZ) of the Andes: its lava field comprises 84 eruptive phases from 35 small eruptive centers. The study of this volcanic field offers a unique opportunity to assess the volumetric, morphometric, rheological, and compositional evolution of the effusive activity in an entire monogenetic cluster; the great extent and exposure of these small eruptive centers is difficult to observe in other monogenetic volcanoes from the Central Volcanic Zone, as they normally appear as isolated vents or in small clusters (< 3 eruptive centers) with less associated eruptive phases. Our methodology utilizes GIS mapping tools to outline the different eruptive phases of El Negrillar to create a detailed lava flow map, allowing us to estimate the volume emitted by each eruptive center. This analysis was also possible through the paleoreconstruction of the buried lava flows, allowing the determination of the variation in the magma supply. This yielded a total bulk volume of ~7.6 km3 (6.8 km3 DRE, considering the low vesicle abundance of the eruptive products), which exceeds by more than one order of magnitude the volume emitted by other monogenetic centers from the Salar de Atacama region (e.g., El País lava flow, Tilocálar Norte, Tilocálar Sur, La Albondiga and Cerro Overo). We also determined the composition of the entire effusive activity of El Negrillar; andesitic magmas represent more than 46 vol% of the lava field. We identify three main clusters (i.e., Northern El Negrillar (NEN), Central El Negrillar (CEN), and Southern El Negrillar (SEN)), that revealed a compositional variation together with a change in the calculated morphometrical and rheological parameters, implying the existence of a local trend within the monogenetic lava field. The NEN cluster represents the most differentiated magmatism in the field, characterized by amphibole-rich lavas with almost absent olivine, and the highest crystallinity and vesicle content, which led to an effusive activity sustained for more than 3 years, with lava accumulation predominating over its transport, leading to the shortest and thickest flows of the field. The presence of “cauliflower shape bombs” in an early stage of one of its eruptive centers indicates that the NEN cluster may have been influenced by environmental factors leading to an early explosive episode during its activity. On the contrary, the SEN cluster represents the less differentiated magmatic activity of the field, characterized by olivine-rich lavas with almost absent amphibole, low crystallinity, and poor vesicles content, which along with a large magma supply led to effusive activity sustained for approximately two years where the lava flows achieved the longest distances in the field. The CEN cluster is compositionally closer to the SEN, but morphometrical and rheologically resembling to the NEN, suggesting that it represents an intermediate behavior between the other two clusters.
Power system coherency assessment by the affinity propagation algorithm and distance correlation
Sustainable Enegy, Grids and Networks
José Ortiz Bejar1 , Mario Roberto Arrieta Paternina2 , Alejandro Zamora Méndez3 , Lucas Lugnani 4 , Eric Téllez 5
1 Universidad Michoacana de San Nicolás de Hidalgo,
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
4 University of Campinas, Department of Electrical Engineering
5 Centro de Investigación e Innovación en Tecnologías de la Información y Comunicación,

Keywords: Coherency, Affinity propagation, Clustering, Phasor measurement units, Frequency, Slow coherency
Abstract: This paper assesses the coherency in power systems employing the affinity propagation (AP) algorithm with different distance metrics and quality measurements. This assessment allows determining the appropriate metric to cluster a frequency dataset that possesses coherent patterns. Thanks to the AP method does not require initialization for the number of clusters, its convergence characteristics guaranteed by the optimization process, and its capacity for using different distance metrics as input, the AP is adopted to identify and distinguish such coherent patterns that embody the collective motion of an operative area in a power system. The AP method is a data-driven method that uses an affinity matrix as input, i.e., the square matrix computed with pairwise distances. Since the distance function significantly impacts the quality of the resulting clustering, this contribution evaluates three different distance metrics, distance correlation, and the results are compared using four cluster indexes. The data collection is constituted by a set of frequency signals and the representative objects are the nodes identified as the center of each operative area. This contribution presents experimental results using simulated signals with added noise and real event signals captured by 94 PMUs. We found that our proposed strategy achieves highly competitive results for identifying coherent generator and non-generator buses in large-scale power systems.
Advanced three-stage photovoltaic system phasor model for grid integration dynamic studies
Solar Energy
Jesús H. Sánchez 1 , Luis Miguel Castro González1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Electrical network, DC/DC boost converter, Dynamic simulations, Phasor modeling, Photovoltaic systems, Voltage source converter
Abstract: As the penetration of photovoltaic (PV) generation increases at different system voltage levels, their impact on the power grid operation and control is more important to analyze. Hence, suitable PV models must be developed with which it is possible to carry out dynamic analysis for fair-sized electrical networks. This is a demanding task, computationally-wise, for detailed switching-based PV models using small numerical integration steps required by the associated power electronic devices. In this sense, an advanced three-stage PV system phasor model is proposed in this paper whose hallmark resides in the proper characterization of the PV arrays and DC/DC converter through a nonlinear potential regression technique in combination with the generatrix method. As a result, the PV operating surfaces, as function of irradiance and temperature, can be determined and used for the calculation of virtual resistances relating to the PV optimal operation and internal power losses. The virtual resistances are seamlessly combined with a developed AC/DC converter phasor model for efficient dynamic simulations of electrical networks. The new PV model has been thoroughly validated using Simscape Electrical of Simulink where an electrical network with one PV system is dynamically simulated. The outcomes of the developed model are compared to those obtained from switching-based PV models based on different maximum power tracking strategies, i.e., the incremental conductance (IC) and perturbation and observation (P&O) algorithms. The impact of the PV system on the power grid operation and the accuracy of results are assessed, demonstrating that the proposed model favorably agrees with the benchmark switching-based PV models as errors inferior to 2 % are obtained. Furthermore, it is confirmed that the new PV system model enables faster dynamic simulations than what it is possible to achieve with switching-based models since it is 28.82 times faster than the PV model based on the IC algorithm and 31.80 times faster than that using the P&O technique.
Study of a current multilevel converter as an interconnection element for PV systems
Ain Shams Engineering Journal
Rafael Jesús Hernández 1 , V. Cárdenas 2 , Gerardo Espinosa Pérez3 , R. Álvarez Salas1 , H. Miranda Vidales1
1 Universidad Autónoma de San Luis Potosí, Facultad de Ingeniería
2 Universidad Autónoma de San Luis Potosí, Centro de Investigación y Estudios de Posgrado
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Current source converter, Multilevel current rectifier, PV system
Abstract: The present paper focuses on the use of the Multilevel Current Rectifier topology as an interconnection element between PV systems and the network or loads. In order to properly use the converter in connection with the PV system, several subjects such as the compatibility with the maximum power point tracking and the compatibility between the converter and the PV array must be taken into account. Compatibility between the converter and the PV array can be achieved by ensuring at least the maximum power point is a point that the converter can work with. In this sense, this work focuses on the operating conditions to guarantee the compatibility with the PV array. The main results are an analytical and experimental characterization of the operating range of the system using the Multilevel Current Rectifier. This operating range has a precision of 1%. Leading to the conclution that not only the converter is a viable option, but also that the theory and methodology used can be extrapolated to another topologies.
On the modelling of DC microgrids for steady-state power flow studies
Electric Power Systems Research
Luis Miguel Castro González1 , Cristóbal Ramírez Ramos1 , Jesús H. Sánchez 1 , Daniel Guillén Aparicio2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Tecnológico de Monterrey, Ingeniería Eléctrica y Electrónica

Keywords: BESS, Cogeneration, Distributed generation, Power flows, Microgrids, PV systems, Wind generators
Abstract: This paper introduces a comprehensive modelling framework for power flow studies of DC microgrids (MG). Suitable AC/DC and DC/DC converter models based on voltage source converters and dual-active bridges are firstly derived. In turn, these are seamlessly combined with battery energy storage systems (BESS) and distributed generators (DG) such as cogeneration, wind generators and photovoltaic systems to give rise to a complete MG representation. The hallmark of this formulation is that all MG component models are derived following basic principles of operation in steady-state in such a way that their internal variables are calculated during the iterative process. The method features a unified formulation through the widely-used power injection concept. For validity purposes, a 13-node MG comprising three DG, two DC/DC converters and one BESS is studied considering both grid-connected and island operation modes. The same MG model was implemented in Matlab/Simscape Electrical using detailed models. Both solutions are shown to agree well with each other since errors inferior to 1% and 2% were obtained for nodal voltages and power flows, respectively. A 118-bus MG including 15 DG units, 5 DC/DC converters and 4 BESS was additionally studied to confirm the practicality of the new approach in larger MG facilities.
Data science - time series analysis of oil & gas production in mexican fields
Procedia Computer Science
María de los Ángeles Sánchez Morales1 , Francisca Irene Soler Anguiano1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Oil, Gas, Production, Time Series Analysis, Seasonal, Non-Seasonal Methods, ARIMA, SARIMA Methods
Abstract: Nowadays, large industries of financial, technological, manufacturing, energetic, and service sectors have accomplished the incorporation of Data Science in their operations, processes, and work structures, obtaining significant improvements in their productivity and service potentials. Whereby the oil and gas industry should not be foreign to this science that aids the decision-making processes using the acquired information by extracting massive, structuring data, combining statistics, mathematics, and informatics. Since the variations in petroleum and gas offer and demand are strongly related to the changes in prices, the use of Data Science intends to administer and reduce the risks provoked by the processes and decisions related to every step of the industry’s chain value. Oil and gas exploration, extraction, development, and production generate considerable amounts of data created by different means, lacking order and precision. Hence, data analysis provides formality to the experiments in this area, improving productivity alternatives and creating innovation opportunities. The present paper objective is to comprehend the production fluctuation trends to understand the possible behaviour of future productions in three Mexican fields with the highest petroleum and gas production, Maloob, Zaap, and Ayatzi for petroleum and Ku, Akal, and Maloob for gas, through the application of a Time Series Analysis to each one of them.
Short-term generation capacity expansion planning considering multi-terminal VSC[sbnd]HVDC links using a linear programming framework improved by shift factors
Electric Power Systems Research
Luis Miguel Castro González1 , Néstor González Cabrera1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: AC/DC systems, Generation capacity expansion planning, VSC-HVDC links, Linear programming, Shift factors
Abstract: This paper describes the modelling of short-term generation capacity expansion planning (GCEP) for multi-terminal VSC-based HVDC transmission systems. The GCEP formulation is based on a mixed-integer linear programming (MILP) framework where transmission losses are considered by piecewise linearisation. As opposed to existing methods, the present GCEP formulation is based on shift factors which enable the representation of the hybrid AC/DC grids including VSC stations. This way new power generation investments can be efficiently determined at any of the VSC-connected AC systems. This new method lies in sharp contrast with the so-called classic GCEP method where the system nodal power balances are formulated using the voltage phase angles as decision variables thus increasing the model complexity. Indeed, to determine the GCEP investments, the present model aimed to multi-terminal HVDC links only uses AC/DC transmission line losses, power generations and projected generating power plants as decision variables. The new GCEP formulation is compared to the classic method using two compelling multi-terminal VSCsingle bondHVDC test systems for validity and applicability purposes. Results show that the proposed formulation reduces the simulation running time by more than 80%, compared to the standard model, accompanied by acceptable accuracy of results since errors inferior to 5% are obtained.
A new angular velocity observer for attitude tracking of spacecraft
ISA Transactions
Eduardo Espíndola López1 , Yu Tang Xu1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Angular velocity observer, Contraction analysis, Global exponential convergence, Separation property, Spacecraft
Abstract: This paper proposes a new angular velocity observer for attitude tracking of spacecraft based on contraction analysis. The observer is designed in the inertial reference frame via estimating the inertial angular momentum to avoid the square term of the angular velocity when the spacecraft dynamics is expressed in the body frame. It employs a continuous angular-velocity dependent innovation term generated by means of a simple first-order linear filter, instead of a discontinuous attitude-dependent innovation term commonly used in angular velocity observer designs, resulting in a smooth behaviour. The global exponential convergence is achieved. Moreover, when combined with the exponentially convergent tracking controller devised in this paper, it gives an overall system with exponential stability relying on a separation property. Finally, a switching function with hysteresis is introduced to stabilize the closest equilibrium in the configuration space, achieving the global exponential stability. Numerical simulations are included to illustrate the performance of the proposed observer in the closed loop, comparison with similar results, and robustness verification under inertia parameter uncertainties and noisy measurements.
Reversible Data Hiding with a New Local Contrast Enhancement Approach
Eduardo Fragoso Navarro1 , Manuel Cedillo Hernández2 , Francisco Javier García Ugalde1 , Robert Morelos-Zaragoza Ascanio3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
3 San Jose State University, College of Engineering

Keywords: Contrast enhancement, histogram shifting, information security, image processing
Abstract: Reversible data hiding schemes hide information into a digital image and simultaneously increase its contrast. The improvements of the different approaches aim to increase the capacity, contrast, and quality of the image. However, recent proposals contrast the image globally and lose local details since they use two common methodologies that may not contribute to obtaining better results. Firstly, to generate vacancies for hiding information, most schemes start with a preprocessing applied to the histogram that may introduce visual distortions and set the maximum hiding rate in advance. Secondly, just a few hiding ranges are selected in the histogram, which means that just limited contrast and capacity may be achieved. To solve these problems, in this paper, a novel approach without preprocessing performs an automatic selection of multiple hiding ranges into the histograms. The selection stage is based on an optimization process, and the iterative-based algorithm increases capacity at embedding execution. Results show that quality and capacity values overcome previous approaches. Additionally, visual results show how greyscale values are better differentiated in the image, revealing details globally and locally.
Thermal analysis using induction and concentrated solar radiation for the heating of metals
Results in Engineering
Armando Rojas Morin1 , Yolanda Flores Salgado2 , Omar Álvarez Brito3 , Alejandro Jaramillo Mora1 , Arturo Barba Pingarrón1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Dirección General de Tecnologías de la Información y Comunicación
3 Universidad Nacional Autónoma de México, Instituto de Energías Renovables

Keywords: Solar energy and electric induction coupling, Metal piece heating, Exergy analysis
Abstract: It is described the thermal analysis of a cylindrical workpiece involving the coupling of two heat sources. Induction heating was applied, which generated Eddy currents that circulated through the workpiece and heated the material surface. Also, concentrated solar energy heating was applied at the top of the workpiece, which generated a heat flux from the Fresnel lens concentrator. The formulation for the transient heat transfer analysis is presented. A numerical simulation for solving Maxwell's equations along with coupled and transient heat transfer conditions was developed using COMSOL Multiphysics®. The temperature distribution of the cylindrical workpiece was obtained, and the heating time was also determined. Subsequently, we compared this simulation and the experimental test. The experimental results show that for the coupling induction and concentrated solar energy, the temperature reaches its maximum faster than induction or concentrated solar energy alone. This kind of proposed alternative system can be useful for time and energy reduction for industrial heat treatments like annealing, precipitation hardening, quenching and tempering, isothermal treatments of ferrous and non-ferrous alloys.
Analysis of the effect of cationic ratio Bi3+/Fe3+ on the magnetic and multiferroic properties of BiFeO3 nanoparticles synthesized using a sonochemical-assisted method
Ceramics International
R.L. Palomino Resendiz1 , Ana María Bolarín Miró1 , F. Pedro García 2 , Félix Sánchez De Jesús1 , J.P. Espinós Manzorro3 , Claudia Alicia Cortés Escobedo4
1 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad de Sevilla, Instituto de Ciencia de Materiales de Sevilla
4 Instituto Politécnico Nacional, Centro de Investigación e Innovación Tecnológica

Keywords: Multiferroic ceramic, Bismuth ferrite (BiFeO3) nanoparticles, Magnetoelectric materials, Sonochemical synthesis, X-ray photoelectron spectroscopy
Abstract: This study examined the effects of the cationic ratio of Bi3+/Fe3+ via X-ray photoelectron spectroscopy (XPS) on the magnetic and multiferroic properties of BiFeO3 nanoparticles synthesized using a sonochemical-assisted method. X-ray diffraction revealed the successful synthesis of single-phase BiFeO3 powder after annealing the sonicated material at 723 K. The powder was composed of agglomerates of rounded particles with a mean particle size of 35 nm. XPS was performed to determine the Bi3+/Fe3+ ratio as a function of the heat treatment process and its relationship with secondary phases, which can modulate the magnetic properties of the nanopowders. The cationic ratio obtained by XPS confirmed that the powders obtained at 623 and 923 K have excess Bi3+ and Fe3+, respectively, which induces the formation of Bi24Fe2O39 and Bi2Fe4O9 as the majority phases. Powder annealing at 723 K revealed a ferromagnetic order with specific magnetization of 1.8 Am2/kg. This ferromagnetic behavior was preserved after applying spark plasma sintering (SPS) at 923 K. By contrast, conventional sintering at 1023 K promotes antiferromagnetic order. In addition, the dielectric properties of the ceramic material of the sintered powders showed a behavior related to a typical ferroelectric material.
Interaction between long water waves and two fixed submerged breakwaters of wavy surfaces
Wave Motion
Eric Gustavo Bautista Godínez1 , S. Bahena Jiménez1 , A. Quesada Torres1 , Federico Méndez Lavielle2 , E. Arcos 3
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Tecnológico de Estudios Superiores de Huixquilucan, División de Ingeniería Civil

Keywords: Long waves, Plate, Wavy surface, Domain perturbation method, Wave reflection
Abstract: In this work, we carried out an asymptotic analysis, up to the second order in a regular expansion, of the interaction between linear long waves and two submerged breakwaters of wavy surfaces, which obey a sinusoidal profile. The governing equations are expressed in their dimensionless version. The boundary conditions at the breakwaters surfaces are non-homogeneous; therefore, they are linearized using the domain perturbation method. Breakwaters with wavy surfaces generate larger reflection coefficient values than those obtained for breakwaters with flat surfaces. The largest values of this coefficient are obtained when the breakwater’s length is of the same order of magnitude as the wavelength. The asymptotic solution is compared with classical analytical solutions and the results are in good agreement. The present asymptotic solution can be used as a practical reference for the selection of the geometric configuration of a submerged floating breakwater under shallow flow conditions.
Volume reduction of water samples to increase sensitivity for radioassay of lead contamination
Applied Water Science
Alexis Aguilar Arevalo1 , Carlos Canet Miquel2 , Miguel Angel Cruz Pérez3 , Alexander Deisting 4 , Adriana Dias 4 , Juan Carlos D' Olivo 1 , Francisco Favela Pérez1 , Estela A. Garcés 5 , Adiv González Muñoz5 , Jaime Octavio Guerra Pulido6 , Javier Mancera Alejandrez6 , Daniel José Marín Lámbarri5 , Mauricio Martínez Montero1 , Jocelyn Monroe 4 , Sean Paling 7 , Simon Peeters 8 , Paul Scovell 7 , Cenk Türkoglu 8 , Eric Vázquez Jáuregui5 , Joseph Walding 4
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares
2 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
3 Universidad Nacional Autónoma de México, Programa de Posgrado en Ciencias de la Tierra
4 University of London, Royal Holloway
5 Universidad Nacional Autónoma de México, Instituto de Física
6 Universidad Nacional Autónoma de México, Facultad de Ingeniería
7 Boulby Mine, Boulby Underground Laboratory
8 University of Sussex, Department of Physics and Astronomy

Keywords: Lead-210, Lead in drinking water, World Health Organisation, Radioassay, Volume Reduction
Abstract: The World Health Organisation (WHO) presents an upper limit for lead in drinking water of 10 parts per billion ppb. Typically, to reach this level of sensitivity, expensive metrology is required. To increase the sensitivity range of low-cost devices, this paper explores the prospects of using a volume reduction technique of a boiled water sample doped with Lead-210 (210 Pb), as a means to increase the solute’s concentration. 210Pb is a radioactive lead isotope and its concentration in a water sample can be measured with e.g. High Purity Germanium (HPGe) detectors at the Boulby Underground Germanium Suite. Concentrations close to the WHO limit have not been examined. This paper presents a measurement of the volume reduction technique retaining 99±(9)% of 210Pb starting from a concentration of 1.9×10-6 ppb before reduction and resulting in 2.63×10-4 ppb after reduction. This work also applies the volume reduction technique to London tap water and reports the radioassay results from gamma counting in HPGe detectors. Among other radio-isotopes, 40K, 210Pb, 131I and 177Lu were identified at measured concentrations of 2.83×103 ppb, 2.55×10-7 ppb, 5.06×10-10 ppb and 5.84×10-10 ppb in the London tap water sample. This technique retained 90±50% of 40K. Stable lead was inferred from the same water sample at a measured concentration of 0.012 ppb, prior to reduction.
Needle path planning in semiautonomous and teleoperated robot-assisted epidural anaesthesia procedure: A proof of concept
The International Journal of Medical Robotics and Computer Assisted Surgery
Daniel Haro Mendoza1 , Fernando Pérez Escamirosa2 , Diego Pineda Martínez3 , Víctor J. González Villela1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
3 Universidad Nacional Autónoma de México, Facultad de Medicina

Keywords: Epidural anaesthesia procedure, needle path planning, percutaneous procedure, semiautonomous robot
Abstract: Background Epidural anaesthesia is a Percutaneous Procedure (PP) which plays a crucial role in surgical procedures, where accurate needle insertion is still challenging. The objective of this work is to present a Tuohy needle path planning, which allows an anaesthesiologist to drive semiautonomously, with the assistance of a teleoperated robot, the tip of the needle during this PP. Methods We capture, analysed and modelled the anaesthetist hands' motion during the execution of this procedure, by synthetising, programing and simulating a parametrised and normalised kinematic constrains dependent on an insertion variable in a virtual robot. Results Two preoperative path planning models were obtained, which provide a teleoperated robot with kinematic constraints to semiautonomously drive a Tuohy needle in the epidural anaesthesia procedure. Conclusions A semiautonomous robot can assist in the execution of this PP using the kinematic constraints obtained from the study of the movement of a specialist's hands.
Study of the in vitro degradation and characterization of the HaCat keratinocytes adherence on electrospun scaffolds based polyvinyl alcohol/sodium alginate
Journal of Applied Polymer Science
Albanelly Soto Quintero1 , Patricia González Alva1 , Alba Covelo Villar1 , Miguel Ángel Hernández Gallegos1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Biodegradable, degradation, porous materials, biocompatibility, electrochemistry
Abstract: Biomaterial scaffolds house and direct cells to grow, exposing them to appropriate growth factors. Most of them are designed to degrade at a controlled rate as the new host tissue replaces them. Here, we show that scaffolds obtained through electrospinning of PVA with 3.5, 4.0, and 5.0 wt% of SA showed a gradual degradation rate under physiological conditions during 100 days of incubation. This behavior is proportional to the SA concentration used, with a mass loss of (41%, 47%, and 49% for each system) after 60 days. Moreover, the dielectric properties (EIS) of the scaffolds correlate with their degradation rate throughout the exposition period (100 days), as indicated by the observed decrease in resistance over time. The 4.0 wt% system showed the lowest capacitance value (1.5 10–5 F) and the highest resistance (4.6106 ohm-cm2) behavior among all concentrations. Additionally, the morphological analysis through SEM and AFM showed a shrank in the surface morphology after the degradation process and determined the degree of roughness (Ra). Higher roughness prior to the cytocompatibility test promoted increased proliferation and adhesion of HaCat cells, as observed in the 4.0 wt% PVA/SA system (1422 nm Ra). These biomaterials have great potential in wound dressing applications.
Effect of curing post-treatment time on mechanical properties and stress distribution of adhesively bonded dissimilar steel-aluminum joints
The International Journal of Advanced Manufacturing Technology
Celso Eduardo Cruz González1 , Benjamín Vargas Arista2 , Saúl Daniel Santillán Gutiérrez3 , Arturo Barba Pingarrón3 , Isidro Guzmán Flores4
1 Centro de Ingeniería y Desarrollo Industrial, Dirección de Ingeniería Mecánica
2 Tecnológico Nacional de México, Instituto Tecnológico de Tlalnepantla
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Autónoma de Coahuila, Facultad de Sistemas

Keywords: Adhesive bonding, Dissimilar joints, Curing, Single lap shear testing, Adhesive fracture
Abstract: Adhesive bonding is a joining technology gaining popularity in automotive and aeronautic industries because it allows weight reduction, adhesive bonds and adhesive dissimilar materials joining which could be part of assembly to be welded to other structure, resulting in thermal cycle that could affect mechanical properties. Dissimilar joints between plates of dual-ten 590/600 dual phase high strength steel and AA6061T6-590 aluminum alloy bonded by MP55420 adhesive were analyzed by means of computational stress analysis, single lap shear testing, failure analysis, thermo-gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Results indicated that after curing at 175 °C during 75 and 120 min, stiffness (measured as Young modulus) increased, ductility was reduced, two principal decomposition stages of mass loss were located from 200 to 500 °C in TGA graphs, and there was no significant change in adhesive chemistry considering FTIR curves. Moreover, maximum load of single lap shear specimens was reduced, color adhesive changed from bright to dark amber, as well as joints failed by adhesive mechanism surpassing shear-strain limit as curing time increased. Computational stress analysis showed that peak normal and shear stresses were generated on both edges of adhesive joints after post-treatment time increased.
Evidence of magnetodielectric coupling in bismuth doped lanthanum ferrite obtained by high-energy ball milling
Physica B: Condensed Matter
Lucía I. Olivares Lugo1 , Félix Sánchez De Jesús1 , O. Rosales González1 , 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: Bi doped LaFeO3, Multiferroic material, Dielectric properties, Perovskite, LaFeO3, Magnetodielectric coupling
Abstract: In this study, the effects of Bi3+ doping of LaFeO3 on the crystal structure and the multiferroic properties of La1-xBixFeO3 (0.0 = x = 0.5, ?x = 0.1) are analyzed. Moreover, the magnetodielectric coupling in these materials is discussed. At low doping levels (x = 0.3 mol), the orthorhombic LaFeO3 stabilizes, and at high bismuth contents (x = 0.4), the orthorhombic BiFeO3 is formed, which was confirmed by determining the Néel temperature (623 K–823 K). The magnetic behavior of the samples shows antiferromagnetic order for all compositions. All the samples showed high relative permittivity values, which increased by doping with Bi3+. Furthermore, the presence of Bi decreased the dielectric dissipation factor, which is attributed to low-crystal-structure distortion. Finally, magnetodielectric coupling in these multiferroic materials is reported for the first time, as observed through changes in the relative permittivity under different applied fields and frequencies.
Exergy analysis of the Mexican energy sector
Sustainable Energy Technologies and Assessments
Daniel Alejandro Pacheco Rojas1 , Gabriel León De los Santos1 , Cecilia Martín del Campo1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Exergy analysis, Energy quality, Exergy Factor, Energy sector analysis, Sustainability indicators
Abstract: This paper proposes a step-by-step, replicable methodology for analyzing the exergy characteristics of a country’s energy system. It introduces a set of indicators comparable to those commonly used to describe national energy systems: (1) exergy intensity (2) exergy destruction per capita, (3) exergy destruction per gross domestic product (GDP), (4) exergy efficiency, and (5) exergetic cost. The energy efficiency of the energy sector in Mexico was roughly 20% lower than energy efficiency, with substantially less improvement over the 15 years from 2013 to 2018. This difference arises from a strong dependency on fossil fuels and associated exergy destruction, which is not immediately apparent when taking only an energy perspective. The economic value of exergy destruction could represent 2.9 % of GDP in Mexico. A decreasing trend in the final exergy consumption is not necessarily reflected in lower exergy destruction. Those indicators provide information about the Jevons’ paradox. And it points to substantial room for efficiency improvements in the energy sector, with important implications for greenhouse gas emissions. Applying the exergy perspective will allow policymakers to understand better opportunities to unlock new efficiencies and improve the sustainability of Mexico’s energy system and those of other countries.
Comparison of Estimates of the Excitation Force for Fault Diagnosis in a Wave Energy Converter
Alejandro González Esculpi1 , María Cristina Verde Rodarte1 , Paul Rolando Maya Ortíz2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fault diagnosis, excitation force estimation, unknown input observer, wave energy converter, renewable energy
Abstract: This work analyzes the effect of estimating the excitation force in a model-based fault diagnosis (FD) of a wave energy converter (WEC). This force is a non-measurable variable related to the elevation of the sea waves at the location of the floater through a non-causal kernel function. Hence, two strategies are studied here: real-time estimates from predicted wave elevation and smoothed estimates from available measurements. To compare the performance of FD schemes based on each estimate, one considers faults in the damping subsystems of a WEC based on the Archimedes wave swing prototype. The FD scheme is also composed of an unknown input observer for fault detection and an estimator of the magnitude of the faults. Numerical simulations with irregular sea waves show improved diagnosis with smoothed estimates of the excitation force, at the expense of introducing some time delay.
Thermal impact induced by the environment in the transport of heavy oils in offshore insulated pipelines: Evaluation of heat transfer
Journal of Petroleum Science and Engineering
R. Flores Quirino1 , O. Pastor Reyes1 , Juan Pablo Aguayo Vallejo1 , Gabriel Ascanio 1 , Federico Méndez Lavielle2 , José Federico Hernández Sánchez1 , Salvador Sánchez 1
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Viscous flow, Conjugate heat transfer, Insulated pipeline, Thermal dependent properties, Dynamic viscosity, Heavy oil
Abstract: In this work, the non-isothermal transport of heavy oils in offshore insulated pipelines is theoretically analyzed. Here, because heavy oils show poor thermostability in terms of the dynamic viscosity, the evaluation of the two physical phenomena involved in the mentioned process (flow hydrodynamics and heat transfer) must be carried out in a coupled manner. In addition, if the performance of this type of transport system is considered, and a novel numerical approach is employed, the present mathematical formulation allows defining the relationship between flow assurance and the thermal impact induced by certain environmental conditions. The above is the main contribution of this work, which is achieved by obtaining the results considering an eigenvalue condition, and making the numerical scheme a useful tool to determine an adequate thermal shielding. First, the heat transfer in the transport system is estimated for given thermal–hydrodynamic conditions, and then, the numerical algorithm corrects the thermal shielding (insulation thickness) in such a way that the flow rate is preserved. In summary, the main results indicate that, when a section of the pipeline has a deficient thermal shielding, the flow hydrodynamics receives a considerable thermal impact, causing a significant reduction in the flow rate. Instead, when the thermal shielding is improved, the flow rate increases as the heat flux that is emitted by the pipeline to the environment is confined. Unfortunately, introducing a strong thermal shielding along the entire length of the pipeline implies an excessive use of thermal insulation (cost–benefit); therefore, rational and adequate use of thermal insulation barriers is the most appropriate condition. Such a conclusion is demonstrated by comparing the two study cases using the same amount of thermal insulation (value of the Graetz–Nusselt relationship); here, the flow rate increases more than double for the case as the thermal shielding is numerically corrected, in comparison to the case when the thermal insulation thickness is constant.
Modelling of renewable energy power plant controllers for steady-state studies using an extended power flow formulation
International Journal of Electrical Power & Energy Systems
Rubén A. Reyes Zamora1 , Pedro F. Rosales Escobedo1 , Luis Miguel Castro González2 , Judith Paniagua Ramírez1 , A. Ruelas 1 , A. Acuña 1 , J. A. Suastegui 1
1 Universidad Autónoma de Baja California, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Droop control, Power flow analysis, Power plant controllers, PV power plants, Wind power plants
Abstract: The increasing penetration of large-scale wind and photovoltaic plants has created new challenges for the secure and reliable operation of power systems. To face these challenges, these renewable plants are composed of numerous inverter-based resources that use centralized controllers to satisfy grid code requirements related to frequency and voltage control, both under dynamic and steady-state conditions. In this paper, an extended power flow formulation is proposed for the steady-state modelling of power plant controllers along with their power flow controls including those associated with droop control, suitable for any plant topology and number of regulation devices. The effectiveness of this modelling approach is validated against WECC generic models using dynamic simulations in PSS®E. For this purpose, a 13-bus 5-generator test system representing a 100-MW renewable power plant is studied. The accuracy of the introduced formulation is demonstrated since it presents absolute errors smaller than 0.2% between both fundamentally different methods. Additionally, the well-known IEEE RTS-96 test system is used to model 29 power plant controllers with 93 generators, thus showing the practicality of the proposed formulation. It can be envisaged that this timely tool is valuable for power system operation and expansion planning considering large-scale variable renewable energy power plants.
A Lipschitz continuous sliding mode control for implicit systems
European Journal of Control
Praveen Babu 1 , Debbie Hernández 2 , Bijnan Bandyopadhyay 3 , Leonid Fridman Golredich4
1 Indian Institute of Technology Bombay, Systems and Control Engineering
2 Instituto Tecnológico de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias
3 Indian Institute of Technology, Systems and Control Engineering
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Implicit systems, Sliding mode control, Sliding surface, Lipschitz continuous control
Abstract: In this paper, implicit systems with uncertain input matrix subjected to matched Lipschitz disturbances are considered. For such kind of systems a Lipschitz continuous control, achieving admissible solutions for implicit systems is proposed. The developed methodology consists of two steps. In the first step a stable sliding surface is designed after transforming the original system into a regular like form. Then a first order sliding mode controller through an integrator is designed which will ensure finite-time convergence to the sliding manifold and the exponential convergence to the origin in spite of the presence of Lipschitz disturbances and uncertain input matrix.
Hydrodynamic cavitation through a bio-inspired fast-closing plunger mechanism: experiments and simulations
Bioinspiration & Biomimetics
Francisco Antonio Godínez Rojano1 , José Enrique Guzmán Vázquez1 , Martín Salinas Vázquez1 , Rogelio Valdés 2 , Carlos Alberto Palacios Morales3 , Oscar Chávez 4
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Iberoamericana, Departamento de Estudios en Ingeniería para la
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituto Tecnológico de Chihuahua, División de Estudios de Posgrado e Investigación

Keywords: Hydrodynamic, cavitations, bio-inspired, fast-closing plunger mechanism, experiments, simulations
Abstract: Experimental and numerical results are reported for the internal and external flow fields evolving in a bio-inspired snapping plunger. The experimental evidence underlines the nature of the dynamic-coupling between the processes taking place inside and outside the device. Two main structures dictate the properties of the external flow field: a strong jet which is followed by a vortex ring. Internally, complex patterns of cavitating structures are simultaneously produced in the chamber and the venturi-like conduit. We find the cavitation cycle to be suitably described by the Rayleigh–Plesset model and, thus, proceed to characterize the coupling of both fields in terms of the fluctuations of the velocity. All main parameters, as well as the energy released to the fluid during the collapse, are found to be within the same order-of-magnitude of previously known experimental results for isolated bubbles of comparable size.
Experimental Study of the Influence of CH4 and H2 on the Conformation, Chemical Composition, and Luminescence of Silicon Quantum Dots Inlaid in Silicon Carbide Thin Films Grown by Remote Plasma-Enhanced Chemical Vapor Deposition
ACS Omega
Rodrigo León Guillén1 , Ana Luz Muñoz Rosas1 , Jesús A. Arenas Alatorre1 , Juan Carlos Alonso Huitrón2 , Ana Laura Pérez Martínez3 , Arturo Rodríguez Gómez1
1 Universidad Nacional Autónoma de México, Instituto de Física
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: Silicon carbide (SiC) has become an extraordinary photonic material. Achieving reproducible self-formation of silicon quantum dots (SiQDs) within SiC matrices could be beneficial for producing electroluminescent devices operating at high power, high temperatures, or high voltages. In this work, we use a remote plasma-enhanced chemical vapor deposition system to grow SiC thin films. We identified that a particular combination of 20 sccm of CH4 and a range of 58–100 sccm of H2 mass flow with 600 °C annealing allows the abundant and reproducible self-formation of SiQDs within the SiC films. These SiQDs dramatically increase the photoluminescence-integrated intensity of our SiC films. The photoluminescence of our SiQDs shows a normal distribution with positive skewness and well-defined intensity maxima in blue regions of the electromagnetic spectrum (439–465 nm) and is clearly perceptible to the naked eye.
Physical impact of a surfactant on the nonlinear oscillations of a microbubble considering a dynamic surface tension and subject to an external acoustic field
Physical Review Fluids
César Yepez Terreros1 , Jorge Luis Naude De la Llave1 , Federico Méndez Lavielle1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: The dynamics of microbubbles under the action of external acoustic forces has become particularly important in several applications. In this work, we are particularly interested in studying the transport of surfactant molecules to the surface of an oscillating microbubble, considering the impact that the dynamic surface tension and temporal evolution of the radius of the microbubble has when an acoustic pressure as a driving force is used to promote the nonlinear oscillations. The resulting governing equations to predict the radius of the microbubble and the evolution of the surfactant at the surface are written in dimensionless form. For these equations, we identify two fundamental dimensionless parameters: the Gibbs elasticity E, and the cohesive (or repulsive) parameter K. Using the physical domain 0=E=10 and -13.2=K=13.2, and considering that the diffusive Péclet number is large, as occurs in some applications, the surfactant concentration equation is solvable by using a similarity transformation, whereas the Rayleigh-Plesset-type equation that includes the influence of the previous parameters E and K is solved by the fourth-order Runge-Kutta method. When the numerical predictions are compared with the well-known cases E=K=0, strong deviations reveal that the oscillation mechanisms can be significantly altered.
Impact of viscous dissipation on the conjugate heat transfer between the walls of a porous microchannel
Physica Scripta
Ian Guillermo Monsivais Montoliu1 , Federico Méndez Lavielle1 , José Joaquín Lizardi Del Ángel2 , Edgar Ali Ramos Gómez1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: Microchannel heat sinks, viscous dissipation, freefem
Abstract: In this work, the finite element method was used to study numerically the viscous dissipation that occurs when a Newtonian fluid circulates through a porous microchannel that operates as a heat sink, in which a constant heat flux is applied from the outer walls of the porous microchannel into the fluid. Taking into account that this is a conjugate problem, where the temperature fields of both the porous medium and the wall are unknown, there are two well-known asymptotic limits in the literature that allow us to obtain the solution for this problem: the first one is the thermally thick wall limit $\left(\gamma /{\beta }_{w}^{2}=1\right)$, which has been widely studied previously by other authors; the second one is the thermally thin wall limit $\left(\gamma /{\beta }_{w}^{2}=25\right)$, where the longitudinal effects of heat conduction in the microchannel wall are considerably more important than the ones occurring in the transverse direction. Therefore, in this study, we analyze the competition between these effects and viscous dissipation, as well as the influence that both have on the temperature profiles of the fluid and the wall. The results show that for Br = 0.1, a notable temperature increase occurs in the system, which offers interesting results that have not been reported in the literature yet, because from ? = 0.6 (Br = 0.1), there is a higher temperature in the center of the microchannel than in the vicinity of the wall; that is, the fluid temperature is higher at ? = 0 with respect to the temperature value at ? = 1. This situation becomes more evident as the Brinkman number increases; for example, for Br = 1, the temperature in the center of the microchannel increases up to 23% with respect to the fluid temperature at the wall. Finally, the decrease of the Darcy number does not have a considerable effect on the temperature profiles.
Development and characterization of sealed anodizing as a corrosion protection for AA2024-T3 in saline media
Materials Today Communications
Alba Covelo Villar1 , Sandra Rodil 2 , X. R. Nóvoa 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 de Vigo, ENCOMAT Grupo

Keywords: Anodized aluminum, Sealants solutions, Fluoropolymer, Corrosion protection, XPS, SECM
Abstract: In the present investigation, a new processing route of anodized aluminum AA2024 was developed by incorporating a hydrophobic top sealant to increase the anti-corrosion properties of the substrate in saline media. Different sealant solutions (boiling water, potassium dichromate, and cerium nitrate) were used after the sealing treatment. The surface structure was characterized by water contact angle, atomic force microscopy (AFM), and scanning electron microscopy (SEM) measurements, while the composition was assessed by X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) evaluated the anticorrosive properties. The microhardness properties were assessed with Vickers testing. Each hydrophobic treatment notably improved the corrosion resistance of the AA2024; however, the cerium nitrate system obtained the best results, given that the morphology of the hydrophobic structure generated lower surface defects with high impedance values and, consequently, very low current. The microhardness properties were positively increased after the surface modification, thus, the hydrophobic sealant improved simultaneously both electrochemical and mechanical properties. The XPS identified the presence of fluorotriethoxysilane as the chemical compound responsible for the hydrophobic properties.
Finite-Time State Observer for a Class of Linear Time-Varying Systems With Unknown Inputs
IEEE Transactions on Automatic Control
Jorge Dávila Montoya1 , Markus Tranninger 2 , Leonid Fridman Golredich3
1 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación
2 Graz University of Technology, Institute of Automation and Control
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Robust observers, finite-time observers, time-varying systems, unknown inputs, high-order sliding modes
Abstract: A finite-time observer for a class of linear time-varying systems with bounded unknown inputs is presented in this note. The design of the observer exploits structural properties of the system and, through a linear operator, allows applying the robust exact differentiator in a block form without requiring additional stabilizing terms. The proposed observer provides an exact estimate of the states after a finite transient time despite the possible instability of the system and the effects of bounded unknown inputs.
Contextual Isotope Ranking Criteria for Peak Identification in Gamma Spectroscopy Using a Large Database
IEEE Transactions on Nuclear Science
Alexis Aguilar Arevalo1 , Xavier Bertou 2 , Carlos Canet Miquel3 , Miguel Angel Cruz Pérez4 , Alexander Deisting 5 , Adriana Dias 5 , Juan Carlos D' Olivo 1 , Francisco Favela Pérez1 , Estela A. Garcés 6 , Adiv González Muñoz6 , Jaime Octavio Guerra Pulido7 , Javier Mancera Alejandrez7 , Daniel José Marín Lámbarri6 , Mauricio Martínez Montero1 , Jocelyn Monroe 5 , Sean Paling 8 , Simon Peeters 9 , Paul Scovell 8 , Cenk Türkoglu 9 , Eric Vázquez Jáuregui6 , Joseph Walding 5
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares
2 Centro Atómico Bariloche,
3 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
4 Universidad Nacional Autónoma de México, Programa de Posgrado en Ciencias de la Tierra
5 University of London, Royal Holloway
6 Universidad Nacional Autónoma de México, Instituto de Física
7 Universidad Nacional Autónoma de México, Facultad de Ingeniería
8 Boulby Mine, Boulby Underground Laboratory
9 University of Sussex, Department of Physics and Astronomy

Keywords: Gamma-ray spectroscopy, heuristic algorithms, isotope identification, ranking
Abstract: Isotope identification is a recurrent problem in ? spectroscopy with high-purity germanium detectors. In this work, new strategies are introduced to facilitate this type of analysis. Five criteria are used to identify the parent isotopes making a query on a large database of ? lines from a multitude of isotopes producing an output list whose entries are sorted so that the ? lines with the highest chance of being present in a sample are placed at the top. A metric to evaluate the performance of the different criteria is introduced and used to compare them. Two of the criteria are found to be superior than the others: one based on fuzzy logic and another that makes use of the ? relative emission probabilities. A program called histoGe implements these criteria using an SQLite database containing the ? lines of isotopes which was parsed from WWW Table of Radioactive Isotopes. histoGe is Free Software and is provided along with the database so they can be used to analyze spectra obtained with generic ? -ray detectors.
Design, Growth, and Characterization of Crystalline Copper Oxide p-Type Transparent Semiconductive Thin Films with Figures of Merit Suitable for Their Incorporation into Translucent Devices
Crystal Growth and Design
María del Pilar Aguilar Del Valle1 , Luis Fernando Garrido 1 , Juan Carlos Alonso Huitrón2 , Luis Augusto Terrones Pacheco1 , Héctor Cruz Manjarrez1 , José Reyes Gasga1 , Ana Laura Pérez Martínez3 , Arturo Rodríguez Gómez1
1 Universidad Nacional Autónoma de México, Instituto de Física
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: The development of high-performance p-type transparent conductive oxides (TCOs) is a scientific challenge. Cupric oxide (CuO) and cuprous oxide (Cu2O) are attractive candidates for manufacturing p-type TCOs due to their optoelectronic properties. However, tailoring the copper oxide optical absorption and sheet resistance using scalable and simple synthesis methods is not easy. This work presents a straightforward and highly reproducible methodology based on DC sputtering plus thermal treatments to manufacture copper oxide p-type TCOs with optimal figures of merit. We demonstrate that a low-temperature long-time annealing is capable of changing the conductivity and average transmittance of a determined copper oxide TCO. Our proposed long thermal treatment produces a decrease in the TCO average transmittance from 82 to 67%, but, in return, it generates an increment in the conductivity of 3 orders of magnitude from 2.5 × 10–5 S/cm up to 0.048 S/cm. We estimate that these p-type TCOs could be used to build diverse translucent experimental devices where a p–n heterojunction is required.
Finding evidence of an ancient platform through magnetometry in Huexotla, Central Mexico
Archaeological Prospection
Denisse L. Argote Espino1 , Alberto Juárez Osnaya1 , Alejandro García Serrano2
1 Instituto Nacional de Antropología e Historia, Dirección de Estudios Arqueológicos
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Archaeological prospection, Central Mexico, geophysical survey, Huexotla, magnetometry, sacred precinct
Abstract: The archaeological zone of Huexotla, east of Mexico Basin, was part of the Acolhuacan lordship, associated to the Mexica domain in the Postclassical period. In this site, several structures have been partially explored, some of which are open to the public. Recent explorations led to the hypothesis that the structures of La Estancia, the Wall and the Community were part of a more complex space that formed the Sacred Precinct of the city. In order to test this postulate, magnetometry was conducted in three areas of the site. By processing Total Field and Vertical Gradient magnetic data, we were able to identify and understand the distribution of underground features like walls, floors and platforms, aiding in the determination of potential excavation areas. Processing the magnetic data with the application of the analytic signal operator allowed more information to be acquired for the recognition of structures of interest. The geophysical results were correlated with the outcomes of archaeological excavations in three structures, confirming the existence of architectural patterns that were not previously detected and supporting the thesis proposed for the ceremonial enclosure.
Journal of Applied Research and Technology
Ricardo Yáñez Valdez1 , Jorge A. Téllez Galván1 , Marcelo López Parra1 , Leonardo Urbiola Soto1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Chatter, cutting force, parallel kinematic machine, parallel mechanism, stability lobe diagram
Abstract: Machine tool chatter causes machining instability, surface roughness, and tool wear in metal cutting processes. A stability lobe diagram based on the theory of regenerative vibration is an effective tool to predict and control the chatter. This paper presents the advances in the mechanical design of a parallel kinematic machine tool. The features that make it ideal for machining tasks, and that make unique in its own way, are highlighted. In addition, the description of the progress of this work will be focused on the analysis of the stability limitation for machining systems to derive the stability lobe diagram with modal analysis of the spindle. A vibratory model is developed by adding cutting forces and including analytical equations for the depth of cut and for the cutting speeds, both depending on the frequency of vibration. A step-by-step procedure provides a stability lobe diagram. The results show that it is relatively easy to provide a relationship between depth of cut and spindle speed. In turn, it makes it easy to compare machining processes under different cutting parameters and conditions.
Fully Developed Temperature Profile for a Power-Law Laminar Nanofluid Flow in a Circular Duct Subject to a Uniform Heat Flux
Nanoscience and Technology: An International Journal
Jorge Armando Ojeda 1 , Federico Méndez Lavielle2
1 Universidad de Colima, Facultad de Arquitectura y Diseño
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Nanofluid, power-law, circular duct, convection, laminar flow
Abstract: In the present work, we develop a theoretical analysis of a fully developed laminar nanofluid flow in a circular duct in a steady state subject to a uniform heat flux condition. The rheological behavior of the base fluid is described with the aid of the power-law model and the nanofluid properties such as dynamic viscosity, thermal conductivity, density, and specific heat are assumed as constants for a fixed value of the volumetric fraction. An analytical solution can be obtained based on the mean temperature concept. The Nusselt number was defined and depends on the dimensionless parameter of the viscosity and the power-law index. The main results reveal that for a maximum value of the volumetric fraction, the Nusselt number decreases drastically for shear-thinning base fluids, whereas for shear-thickening base fluids it tends asymptotically to a constant value. For an increase in the volumetric fraction value, the dimensionless velocity profiles have shown lower values for shear-thinning base fluids and the dimensionless temperature profiles present a greater difference between the dimensionless wall temperature and the nanofluid stream temperature.
Assessment of vulnerability to water shortage in the municipalities of Mexico City
Boletin de la Sociedad Geologica Mexicana
Alma R. Huerta Vergara1 , Saúl Arciniega Esparza2 , Adrián Pedrozo Acuña3 , Arnoldo Matus Kramer4 , Eduardo Vega López5
1 Universidad Nacional Autónoma de México, Posgrado en Ciencias de la Sostenibilidad
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Comisión Nacional del Agua, Instituto Mexicano de Tecnología del Agua
4 ITHACA Environmental,
5 Universidad Nacional Autónoma de México, Facultad de Economía

Keywords: Water vulnerability, water supply, exposure, adaptive capacity, urbanization, Mexico City.
Abstract: Water issues in Mexico City have been severe during the last years due to population increase, forcing external water sources to meet water demands. This research aims to evaluate the evolution of water vulnerability in the sixteen municipalities of Mexico City in the years 2005, 2010, and 2015. This vulnerability has increased in the last decades due to the combination of several problems such as lack of maintenance in the water infrastructure (eg. water leaks), aquifer overexploitation, uncontrolled city growth, rainwater and wastewater expelled from the basin without the intention of using it. For the vulnerability assessment we used a combination of indicators that respond to its three dimensions: 1). Exposure (urbanization, population, and economic units), 2). Sensitivity (reports of leaks, shortages, and poor water quality) and 3). Adaptive capacity (wastewater treatment, water availability, and GDP). The municipalities identified with very high vulnerability in the three years of study (2005, 2010, and 2015) were Iztapalapa, Gustavo A. Madero, and Tlalpan joined these during 2015. In contrast, those with the lowest vulnerability were Milpa Alta, Magdalena Contreras, and Cuajimalpa; the latter stepped down from having Low to Very Low vulnerability between 2005 and 2010-2015. Between these two classifications, we have the Municipalities that reveal high, moderate, and low vulnerability. The results highlight that all municipalities must prevent water leaks to achieve increasingly sustainable management of the liquid, especially Gustavo A. Madero, Iztapalapa, and Tlalpan. Suggesting that harmonized action among all of them will help accelerate goal achievement. Still, citizen action will play a leading role in maintaining care and water usage levels when promoted and encouraged adequately. At the end of the lecture, the reader would be able to discuss if a series of social elements (like the indicators proposed in this work) construct water vulnerability or depend on the quantity of water the cities receive. Also, they will understand their role in water management and have factors to evaluate vulnerability in other regions.
Electromechanical Modes Identification Based on an Iterative Eigenvalue Decomposition of the Hankel Matrix
IEEE Transactions on Power Systems
Alejandro Zamora Méndez1 , Rodrigo Reyes De Luna2 , José Antonio De la O Serna 3 , Joe H. Chow 4 , Mario Roberto Arrieta Paternina5
1 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
2 Universidad Autónoma de Nuevo León, Ingeniería Eléctrica
3 Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica
4 Rensselaer Polytechnic Institute, Department of Electrical Computer and Systems Engineering
5 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Electromechanical oscillations, eigenvalue decomposition, Hankel matrix, time-frequency representation, nonstationary signals
Abstract: This paper proposes a novel strategy to precisely extract modal patterns from non-stationary multi-component signals associated with electromechanical oscillations in large-scale power systems. The strategy is composed of two stages: (i) a time-frequency representation (TFR) method; and (ii) an energy-based operator. The former is equipped with a multivariate and iterative eigenvalue decomposition of the Hankel matrix (IEVDHM) that captures the swing dynamics as a mono-component signal criterion is fulfilled, meanwhile the latter instantaneously estimates the modal information (damping and frequency) through the discrete energy separation algorithm (DESA) that implements the discrete-time energy operators derived from the Teager-Kaiser energy operators (TKEO). The attained results and their comparisons with state-of-the-art techniques confirm the effectiveness and performance of the proposed strategy to demodulate synthetic, simulated and real oscillating signals, even under high noisy conditions, and to be a useful tool for off-line contingency analysis thanks to the capability of differentiating concurrent modes with close frequencies.
On Active Vibration Absorption in Motion Control of a Quadrotor UAV
Francisco Beltrán Carbajal1 , Hugo Yañez Badillo2 , Rubén Tapia Olvera3 , Antonio Favela Contreras4 , Antonio Valderrabano González5 , Irvin López García1
1 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
2 Tecnológico Nacional de México, Tecnológico de Estudios Superiores de Tianguistenco
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Tecnológico de Monterrey, Escuela de Ingeniería y Ciencias
5 Universidad Panamericana, Facultad de Ingeniería

Keywords: Vibration control, dynamic vibration absorbers, aerial vehicles; quadrotor, motion tracking control
Abstract: Conventional dynamic vibration absorbers are physical control devices designed to be coupled to flexible mechanical structures to be protected against undesirable forced vibrations. In this article, an approach to extend the capabilities of forced vibration suppression of the dynamic vibration absorbers into desired motion trajectory tracking control algorithms for a four-rotor unmanned aerial vehicle (UAV) is introduced. Nevertheless, additional physical control devices for mechanical vibration absorption are unnecessary in the proposed motion profile reference tracking control design perspective. A new dynamic control design approach for efficient tracking of desired motion profiles as well as for simultaneous active harmonic vibration absorption for a quadrotor helicopter is then proposed. In contrast to other control design methods, the presented motion tracking control scheme is based on the synthesis of multiple virtual (nonphysical) dynamic vibration absorbers. The mathematical structure of these physical mechanical devices, known as dynamic vibration absorbers, is properly exploited and extended for control synthesis for underactuated multiple-input multiple-output four-rotor nonlinear aerial dynamic systems. In this fashion, additional capabilities of active suppression of vibrating forces and torques can be achieved in specified motion directions on four-rotor helicopters. Moreover, since the dynamic vibration absorbers are designed to be virtual, these can be directly tuned for diverse operating conditions. In the present study, it is thus demonstrated that the mathematical structure of physical mechanical vibration absorbers can be extended for the design of active vibration control schemes for desired motion trajectory tracking tasks on four-rotor aerial vehicles subjected to adverse harmonic disturbances. The effectiveness of the presented novel design perspective of virtual dynamic vibration absorption schemes is proved by analytical and numerical results. Several operating case studies to stress the advantages to extend the undesirable vibration attenuation capabilities of the dynamic vibration absorbers into trajectory tracking control algorithms for nonlinear four-rotor helicopter systems are presented.
Effect of oils on the transmission properties of a terahertz photonic crystal
Applied Optics
Dahí Ludim Hernández Roa1 , Yesenia A. García Jomaso1 , Neil C. Bruce 1 , Jesús Garduño Mejía1 , Oscar Pilloni 2 , Laura Oropeza Ramos3 , Carlos Gerardo Treviño Palacios4 , César L. Ordoñez Romero5 , Armando M. Velázquez Benítez1 , Naser Qureshi 1
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituto Nacional de Astrofísica Óptica y Electrónica,
5 Universidad Nacional Autónoma de México, Instituto de Física

Abstract: The transmission properties of a photonic crystal immersed in several different oils have been characterized using terahertz time domain spectroscopy in the spectral range of 0.3–1.5 THz. As in previous works, oil samples can be distinguished using terahertz transmission measurements. When the same oils are introduced into a photonic crystal, we find that the effective refractive index of the photonic crystal is sensitive to the properties of the oils and shows differences not seen in bulk measurements. These effects are described in detail and have potential applications in both the sensing of very small volumes of oils and in the fine control of the refractive indices of photonic crystals.
Estudio numérico-experimental del campo de velocidades en un canal rectangular con curvatura compuesta y ancho variable en 2DH
Tecnología y Ciencias del Agua
José Luis Aragón Hernández1 , Christian Alberto Caballero Coranguez2 , Amado Abel Jiménez Castañeda2 , Moisés Berezowsky Verduzco2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Canal curvo, modelación numérica bidimensional horizontal, hidrodinámica, turbulencia, separación de flujo
Abstract: Se presenta un análisis de la aproximación obtenida con los sistemas de modelación matemática HEC-RAS, Iber y Telemac–Mascaret para el cálculo del campo de velocidades en un canal de sección rectangular con curvatura compuesta y ancho variable; en el canal se desarrollaron corrientes secundarias y separación de flujo; los tres modelos son de uso libre y se basan en la hipótesis de flujo bidimensional horizontal (2DH). Se utilizan las ecuaciones de Saint Venant en cada modelo matemático para calcular la hidrodinámica y la turbulencia. El campo de velocidades se determina a partir de mediciones físicas en un canal de laboratorio con un velocímetro Doppler acústico (Micro-ADV 16 MHz) y se compara con los campos de velocidades calculados con los sistemas de modelación matemática (HEC-RAS, Iber y Telemac–Mascaret). Se presenta un análisis de errores, con el objetivo de determinar el grado de aproximación obtenido con cada sistema de modelación, y la discusión de los factores y fenómenos observados en el laboratorio, esto permite tener conocimiento sobre la complejidad en la naturaleza de los flujos turbulentos en canales con curvaturas fuertes. Se encontró que los tres modelos, en general, tienen un comportamiento similar y aceptable, con una aproximación promedio superior al 93 %; en cambio, en un análisis por sección, en una zona de recirculación, se observó separación del flujo y alta turbulencia (procesos físicos de la dinámica del fluido que los modelos empleados no pueden reproducir de forma adecuada); la aproximación promedio disminuye hasta el 82.5 %.
Effect of heat treatment on friction and tribolayer formation in copper
Tribology International
Carlos Gabriel Figueroa Alcántara1 , Rafael Schouwenaars Franssens1 , Roumen Petrov 2 , Leo Kestens 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Ghent University, EEMMeCS Department

Keywords: Adhesive wear, Sliding friction, Surface structure, Plastic contact
Abstract: This work analyses the effect of annealing conditions on tribolayer formation in copper under dry sliding conditions. Cold rolled material and samples annealed during 15, 30 and 45 min at 600 °C show an increase in grain size, decrease in hardness and increase in toughness and ductility with time. Electron backscattered diffraction maps describe the severe plastic deformation of a nanostructured tribolayer. Friction coefficients decrease with annealing times, while surface damage diminishes. Wear is lower in the softer material. This is explained by the energy required to produce surface damage, in combination with the energy transmitted to the substrate by friction.
Stress corrosion cracking of the slip-ring connectors of a 2 MW wind turbine
Engineering Failure Analysis
Edgar Isaac Ramírez Díaz1 , Carlos Gabriel Figueroa Alcántara1 , Jorge L. Romero 1 , Efraín Ramos 1 , Rafael Schouwenaars Franssens1 , Armando Ortiz Prado1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Wind turbine, OFHC copper, Stress corrosion cracking, Atmospheric corrosion
Abstract: The failure of the connectors between the slip ring and rotor of a 2 MW wind turbine was investigated. Visual inspection, low magnification stereomicroscopy and scanning electron microscopy showed the presence of highly branched transgranular cracks. The cracks are in zones of increased stress, as demonstrated by finite elements. The observations show that the failure is caused by stress corrosion cracking (SCC). Fourier transform infrared spectroscopy (FTIR) was used to characterise the insulating varnish of the slip ring. Tropical climate conditions cause the wetting of the components and with a close-by livestock plant is a source of NH3 contamination. Corrections to the design and manufacturing process of the slip rings were suggested to increase the life expectancy of the generator, although the selection of an insulating varnish with higher resistance to environmental exposure is probably the most efficient manner to reduce the incidence of this phenomenon in the future.
Numerical simulation of a flow induced by the high-speed closure of a bioinspired claw
Journal of Fluid and Structures
Martín Salinas Vázquez1 , Francisco Antonio Godínez Rojano1 , William Vicente 1 , José Enrique Guzmán Vázquez1 , José Valdés 2 , Carlos Alberto Palacios Morales2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Large Eddy Simulation, Claw closure, Cavitation, Shrimp, Immersed boundaries
Abstract: We present the numerical simulations of the flow in a simple mechanical device inspired by the snapping-claw mechanism of alpheidae shrimps. The simulations were based on the entropically damped artificial compressibility (EDAC) method. The governing equations of fluid dynamics were discretized using high-order spatial and temporal schemes. The solid bodies were modeled on the computational domain by using the immersed boundaries method. High-speed video and Particle Image Velocimetry (PIV) measurements of the flow generated in a physical model were used to validate the numerical results. Based on these, we were able to explain the behavior of the flow during the entire length of the closing of the device’s claw and moments after. A simple model was also implemented to predict the steam dynamics. The experimental results confirmed the numerical results. The cavitation process in the mechanical device was correctly modeled and understood.
Practical Mathematical Model for the Evaluation of Main Parameters in Polymer Flooding: Rheology, Adsorption, Permeability Reduction, and Effective Salinity
ACS Omega
Javier Rosado Vázquez1 , José Luis Bashbush Bauza1 , Simón López Ramírez1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Permeability, Polymer solutions, Polymers, Redox reactions, Viscosity
Abstract: Polymer flooding is one of the most used chemical enhanced oil recovery (CEOR) technologies worldwide. Because of its commercial success at the field scale, there has been an increasing interest to expand its applicability to more unfavorable mobility ratio conditions, such as more viscous oil. Therefore, an important requirement of success is to find a set of design parameters that balance material requirements and petroleum recovery benefits in a cost-effective manner. Then, prediction of oil recovery turns out to handle more detailed information and time-consuming field reservoir simulation. Thus, for an effective enhanced oil recovery project management, a quick and feasible tool is needed to identify projects for polymer flooding applications, without giving up key physical and chemical phenomena related to the recovery process and avoiding activities or projects that have no hope of achieving adequate profitability. A detailed one-dimensional mathematical model for multiphase compositional polymer flooding is presented. The mathematical formulation is based on fractional flow theory, and as a function of fluid saturation and chemical compositions, it considers phenomena such as rheology behavior (shear thinning and shear thickening), salinity variations, permeability reduction, and polymer adsorption. Moreover, by setting proper boundary and initial conditions, the formulation can model different polymer injection strategies such as slug or continuous injection. A numerical model based on finite-difference formulation with a fully implicit scheme was derived to solve the system of nonlinear equations. The validation of the numerical algorithm is verified through analytical solutions, coreflood laboratory experiments, and a CMG-STARS numerical model for waterflooding and polymer flooding. In this work, key aspects to be considered for optimum strategies that would help increase polymer flooding effectiveness are also investigated. For that purpose, the simulation tool developed is used to analyze the effects of polymer and salinity concentrations, the dependence of apparent aqueous viscosity on the shear rate, permeability reduction, reversible–irreversible polymer adsorption, polymer injection strategies on petroleum recovery, and the flow dynamics along porous media. The practical tool and analysis help connect math with physics, facilitating the upscaling from laboratory observations to field application with a better-fitted numerical simulation model, that contributes to determine favorable scenarios, and thus, it could assist engineers to understand how key parameters affect oil recovery without performing time-consuming CEOR simulations.
Optimizing Broadband Emission in 2D Halide Perovskites
Chemical Engineering & Technology
Carina Pareja Rivera1 , Julio A. Morán Muñoz1 , Ana Paulina Gómora Figueroa2 , Vojtech Jancik 3 , Brenda Vargas 1 , Joelis Rodríguez Hernández4 , Diego Solis Ibarra1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Química
4 Centro de Investigación en Química Aplicada,

Abstract: Broadband and white-light emitting materials are sought after for applications such as phosphors and LEDs. Some two-dimensional (2D) halide perovskites are promising candidates in this realm. Nevertheless, optimizing their photoluminescence quantum efficiency (PLQY) is highly challenging. Herein, we show a new strategy for optimizing the efficiency of the broadband emission of 2D halide perovskites. Specifically, we show that by a combination of halide bonds and halide mixing, the PLQYs of a novel family of materials with the formula (Br-PEA)2PbBrxCl4–x (Br-PEA = 4-bromo phenethylammonium) can be improved by one order of magnitude, from 3 to 25%; this approach could be useful to many other 2D perovskites.
Analysis of the equivalent plastic displacement influence on chip morphology during the orthogonal cutting process using CEL modeling
International Journal of Advanced Manufacturing Technology
Mark Vargas 1 , Edgar Isaac Ramírez Díaz1 , Osvaldo Ruiz Cervantes1 , Carlos Reyes Ruiz 1 , Armando Ortiz Prado1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Orthogonal cutting, chip morphology, finite element modeling, CEL analysis
Abstract: Machining is one of the more widely used manufacturing processes in the industry, for this reason, several studies have focused on predicting the effect of variables related to it. In this work, the effect of the equivalent plastic displacement on the orthogonal cutting process, using coupled Lagrangian–Eulerian (CEL) analysis was studied. The workpiece was considered Eulerian solid material to simulate its interaction with the cutting tool and thus, predict material separation and chip morphology. In the present model, the chip morphology was evaluated in terms of the equivalent plastic displacement, segmented chip formation was achieved without the necessity to apply a method of mesh separation and undeleting elements during the calculation solution, which represents an important advantage over the purely Lagrangian method. Additionally, the cutting forces, contact length, angle of the cutting plane, as well as stress, strain, and temperature distribution were obtained.
A SLAM system based on Hidden Markov Models
Informatics and Automation
Oscar Fuentes 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: localization, SLAM, robot navigation, mapping, Hidden Markov Model, sensor
Abstract: Methods of simultaneous localization and mapping (SLAM) are a solution for the navigation problem of service robots. We present a graph SLAM system based on Hidden Markov Models (HMM) where the sensor readings are represented with different symbols using a number of clustering techniques; then, the symbols are fused as a single prediction, to improve the accuracy rate, using a Dual HMM. Our system’s versatility allows to work with different types of sensors or fusion of sensors, and to implement, either active or passive, graph SLAM. A graph-SLAM approach proposed by the International’s Karto Robotics in Cartographer, the nodes represent the pose of the robot and the edges the constraints between them. Nodes are usually defined according to contiguous nodes except when loop closures are detected where constraints for non-contiguous nodes are introduced, which corrects the whole graph. Detecting loop closure is not trivial; in the ROS implementation, scan matching is performed by Sparse Pose Adjustment (SPA). Cartographer uses an occupancy map in order to estimate the position where the map representation is done via Gmapping. The Toyota HSR (Human Support Robot) robot was used to generate the data set in both real and simulated competition environments. In our SLAM representation, we have wheel odometry estimate according to initial position of the robot, a Hokuyo 2D Lidar scan for observations, and a signal control and a world representation is estimated. We tested our system in the kidnapped robot problem by training a representation, improving it online, and, finally, solving the SLAM problem.
Sparse-Map: automatic topological map creation via unsupervised learning techniques
Advanced Robotics
Jesús Hernández 1 , Jesús Savage Carmona1 , Marco Negrete 1 , Luis Contreras Toledo2 , Carlos Sarmiento 1 , Oscar Fuentes 1 , Hiroyuki Okada 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Tamagawa University, Advance Intelligence and Robotics Research Center

Keywords: Robot mapping, mobile robot navigation, spatial clustering, unsupervised learning
Abstract: Most robots use 2D occupancy grid maps for navigation, localization, and path-planning. This model is flexible and allows to represent any geometrical shape with finite accuracy. However, this dense representation imposes high memory requirements and does not generalize well to 3D environments. We present a task-based map compression technique useful for path-planning and navigation in indoor environments for service robots where, from a point cloud of 3D map features, we calculate a number of clusters based on their spatial position and generate a sparse 3D representation of the environment. Moreover, we propose several metrics to assess the quality and performance of a map representation, and we tested our proposal using a series of point-cloud benchmarks and clustering techniques where our method has a comparable performance using a fraction of the memory footprint than the baselines. Finally, we have released our system as a Robot Operating System (ROS) based open source library.
Hermite Transform Based Algorithm for Detection and Classification of High Impedance Faults
IEEE Access
Daniel Guillen 1 , Jimena Olveres 2 , Vicente Torres García3 , Boris Escalante Ramírez3
1 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Classification, distribution grids, fault detection, Hermite transform, high impedance faults, multiresolution analysis, photovoltaic systems
Abstract: This work proposes a new algorithm to classify high impedance faults (HIFs) in distribution systems. HIFs can be represented by small current magnitudes with non-linear variations, which complicate their detection in distribution grids. The proposed method uses the Hermite transform (HT) as a signal processing technique that offers several advantages, one of the more important being the ability to analyze the signal at multiple resolution levels and at different frequency bands thanks to their filter functions based on Gaussian derivatives. The Hermite coefficients are used to extract signal features that allow efficient identification of the transient behaviour related to HIFs and other typical faults. In this sense, a multichannel approach based on the Hermite transform is proposed to classify different types of faults and HIFs. This analysis is carried out in a distribution network considering photovoltaic (PV) systems considering three different classifiers, which are also used to compare our results with the discrete wavelet transform (DWT) as signal decomposition model; the comparison suggests that our proposal presents better performance discriminating HIFs from typical faults.
Personalized protocol and scoring scale for functional electrical stimulation of the hand: A pilot feasibility study
Technology and Health Care
Jessica K. Camacho Zavala1 , Ana Laura Pérez Martínez1 , Jorge A. Mercado Gutiérrez2 , Mario Gutiérrez 2 , Josefina Gutiérrez Martínez2 , A. Valeria Aguirre Güemez3 , Fresnedo Quinzaños Jimena3 , Javier Pérez Orive1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", División de Investigación en Ingeniería Médica
3 Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", División de Rehabilitación Neurológica

Keywords: Electric stimulation, upper extremity, motor activity, electrodes, rehabilitation, technology
Abstract: Complex personalized Functional Electrical Stimulation (FES) protocols for calibrating parameters and electrode positioning have been proposed, most being time-consuming or technically cumbersome for clinical settings. Therefore, there is a need for new personalized FES protocols that generate comfortable, functional hand movements, while being feasible for clinical translation. OBJECTIVE: To develop a personalized FES protocol, comprising electrode placement and parameter selection, to generate hand opening (HO), power grasp (PW) and precision grip (PG) movements, and compare in a pilot feasibility study its performance to a non-personalized protocol based on standard FES guidelines. METHODS: Two FES protocols, one personalized (P1) and one non-personalized (P2), were used to produce hand movements in twenty-three healthy participants. FES-induced movements were assessed with a new scoring scale which comprises items for selectivity, functionality, and comfort. RESULTS: Higher FES-HSS scores were obtained with P1 for all movements: HO (p= 0.00013), PW (p= 0.00007), PG (p= 0.00460). Electrode placement time was significantly shorter for P2 (p= 0.00003). Comfort scores were similar for both protocols. CONCLUSIONS: The personalized protocol for electrode placement and parameter selection enabled functional FES-induced hand movements and presented advantages over a non-personalized protocol. This protocol warrants further investigation to confirm its suitability for developing upper-limb rehabilitation interventions with clinical translational potential.
Neutronic assessment of a PWR-type SMR core with TRISO particles using mixed-oxide fuel strategies
Progress in Nuclear Energy
Jesús Rosales 1 , Juan Luis François Lacouture1 , Carlos García 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de La Habana, Insituto Superior de Tecnologías y Ciencias Aplicadas

Keywords: SMR, TRISO, SERPENT, MOX fuel
Abstract: The global transition towards a CO2-free energy economy will be possible to the extent that nuclear energy has the capacity to produce energy safely with a proper waste management. The use of Small Modular Reactors, Light Water Reactors-type can solve these problems due to their safety advantages and accumulated operational experience. To achieve a high proliferation resistance, it is proposed that these reactors have extended fuel cycles and for this, the use of Mixed-Oxide (MOX) fuels within Tri-structural Isotopic (TRISO) particles can improve the nuclear waste management, as well as the safety of these reactors. This paper evaluates the performance of a PWR-type SMR core, using TRISO particles, composed by recycled plutonium, in mixtures with depleted uranium and thorium as fertile materials. One-third of the fuel assemblies that make up the reactor core are composed by mixed oxide fuels whereas the rest of the fuel assemblies by UO2. A comparison of four MOX fuel strategies is carried out with a standard full-UO2 cycle, in terms of cycle length, burnup and safety parameters at the end of a cycle of approximately four years. The results show that the use of these compositions meets the safety requirements and variants such as the one that uses plutonium from multiple reprocessing has a well-suited performance for this reactor, compared to the standard UO2 cycle.
Assessment of Chemical Risks Associated with Hydrometeorological Phenomena in a Mexican Port on the Gulf of Mexico
Journal of Marine Science and Engineering
Guadalupe Isabel Lara Carvajal1 , Rodolfo Sosa Echeverría2 , Víctor Magaña 3 , Georgina Fernández Villagómez1 , Jonathan D. W. Kahl 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ciencias de la Atmósfera y Cambio Climático
3 Universidad Nacional Autónoma de México, Instituto de Geografía
4 University of Wisconsin-Milwaukee, School of Freshwater Science

Keywords: risk assessment; storage tanks; extreme wind; port facility; NaTech (natural–technological)
Abstract: Accidents in port areas in the Gulf of Mexico have had great economic costs, since this is an area exposed to extreme phenomena. Tropical cyclones or cold fronts, also known as Tehuantepecers, result in intense winds and waves that impact the coastal infrastructure. The chemical risk associated with extreme winds and waves for the fuel storage tanks of the facility of the Port of Veracruz, the main Mexican port in the Gulf of Mexico, was evaluated with a historical analysis of accidents as a tool to identify significant factors in disasters and establish risk acceptance criteria. It was found that the critical hazard threshold for Veracruz corresponds to winds stronger than 160 km/h (44 m/s) that may result in coastal waves of more than 5 m high. The vulnerability to these phenomena was calculated with the vulnerability index (VI), considering the structural, functional, and chemical factors in the infrastructure, including exposure levels. By means of a risk matrix, it was determined that gasoline storage tanks have a moderate chemical risk, since exposure to the extreme wind wave hazard is low, and diesel tanks are at low risk. These assessments are important elements to consider in the expansion plans for the Port of Veracruz.
Generalized Super-Twisting for Control Under Time- and State-Dependent Perturbations: Breaking the Algebraic Loop
IEEE Transactions on Automatic Control
Hernan Haimovich 1 , Leonid Fridman Golredich2 , Jaime Alberto Moreno Pérez3
1 Centro Internacional Franco-Argentino de Ciencias de la Información y de Sistemas, CONICET-UNR
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Disturbance-tailored, perturbations, sliding-mode control (SMC), super-twisting (ST) algorithm
Abstract: Application of sliding-mode control strategies based on (generalized) super-twisting (ST) algorithms in the presence of time- and state-dependent perturbations is highly challenging. One of the difficulties lies in the occurrence of a kind of algebraic loop; the bounds required for control design require bounds on the control variable, which itself depends on the control to be designed. Existing results were able to partially solve this problem by means of one form of generalized ST, provided that some perturbation-related functions admit constant bounds. In this article, we provide an important generalization by employing disturbance-tailored ST ideas. The current results allow for far greater applicability, since the bounds required need not be constant as long as their growth can be related to the sliding variable.
Photovoltaic Energy Conversion System Integrated Into Unbalanced Distribution Electrical Networks Through Hardware in the Loop
IEEE Journal of Emerging and Selected Topics in Power Electronics
Sergio Fernando Rodríguez Contreras1 , Nadia Maria Salgado Herrera2 , Miguel Robles 2 , Juan Ramón Rodríguez Rodríguez1 , Néstor González Cabrera1 , Mario Alberto Santoyo Anaya3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Energías Renovables
3 Tecnológico Nacional de México,

Keywords: Hardware in the loop (HIL), photovoltaic energy conversion system (PVECS), power electronics converters, real-time simulation, renewable energies, unbalanced distribution electrical networks
Abstract: In this article, a real-time, hardware in the loop (HIL) and experimental photovoltaic energy conversion system (PVECS) integrated into unbalanced distribution electrical networks is presented. Commonly, the three-phase voltages are not balanced, because the input–output of single-phase loads in low and medium voltage networks. In this context, the photovoltaic (PV) systems integration under the dq0-Frame control operation scheme, tend to generate current deformations. In contrast, a new control technique for PVECS interconnection is validated in a HIL scheme, even in the presence of unbalanced voltage. This new technique is considered simple and easy to implement, since it consists of a single PI control loop, guaranteeing reliable operation under unbalances voltage events. Thus, preserving favorable characteristics, such as: 1) always balanced currents; 2) low harmonic distortion; 3) unit power factor; and 4) Compliance with the rules of the network code. The PVECS effectiveness is assessed by complete mathematical model, the simulation results are evaluated using MATLAB-Simulink (MATLAB r2018, Mathworks, Natick, MA, USA), and the experimental results are validated with a small-scale prototype operating in a HIL environment and the real-time simulator Opal-RT Technologies (Montreal, QC, Canada); integrating a power capacity of 15 kW in distribution networks.
Current Source Topologies for Photovoltaic Applications: An Overview
Oscar Miguel Rodríguez Benítez1 , Juan Antonio Aqui Tapia2 , Isaac Ortega Velázquez1 , Gerardo Espinosa Pérez1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Acuity Brands Lighting de México,

Keywords: photovoltaic (PV) systems, current-fed, multi-stage converter, current source converter, reliability
Abstract: Current source topologies have several advantages compared to conventional voltage systems. Their inherent voltage-boosting function, intrinsic short-circuit protection, no electrolytic capacitor, direct-current control, continuous input current, and high reliability make them exceptional candidates for power generation systems, particularly for photovoltaic applications. This study provides an overview of the current source topologies for multi-stage photovoltaic grid-connected systems by comparing the number of components, performance, power-decoupling techniques, efficiency, and frequency operation. The overview reveals gain, performance, energy quality and lifetime improvements, thereby providing current source systems as an attractive alternative for renewable applications.
Método eficiente para integrar los costos de la generación eólica en el modelado de la expansión de la capacidad de generación
IngenIería InvestIgacIón y tecnología
Néstor González Cabrera1 , Luis Osvaldo Martínez Lara2 , Vicente García Torres1 , Nadia Herrera Salgado3 , Juan Ramón Rodríguez Rodríguez1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Posgrado de postgraduados en ingeniería en energías
3 Universidad Nacional Autónoma de México, Instituto de Energías Renovables

Keywords: Generación eólica, expansión de la generación, planeación, sistemas eléctricos de potencia.
Abstract: En este trabajo se presenta un método eficiente para integrar los costos operativos de la capacidad de la generación eólica, que incluya la red eléctrica linealizada, obteniendo una curva hipotética horaria capaz de representar el comportamiento de los generadores eólicos para su integración al modelo de planificación de expansión de la capacidad de generación. Finalmente, se integrará el modelo de la red eléctrica y la curva hipotética horaria al modelo de planificación de la expansión de la capacidad de generación y se estudiará su impacto técnico económico de considerar diversos agrupamientos para el modelado del aerogenerador. La metodología implementada mostró resultados eficientes al incorporar curvas hipotéticas horarias de la velocidad del viento al modelo de expansión de la capacidad de la generación, sin la necesidad de considerar la distribución de probabilidad de la velocidad del viento, logrando reducir los tiempos de simulación en un 99 % respecto a considerar todo el periodo de operación anual, esto permite ahorrar recursos computacionales y analizar el comportamiento de la generación eólica y su implicación económica en un sistema eléctrico.
Reluctance-Based Circuit for High-Temperature Superconductor Generator Lumped-Parameter Model
IEEE Transactions on Magnetics
Alejandro Baez Muñoz1 , Frédéric Trillaud Pighi2 , Juan Ramón Rodríguez Rodríguez1 , Luis Miguel Castro González1 , Rafael Escarela Pérez3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Autónoma Metropolitana, Unidad Azcapotzalco

Keywords: Magnetic equivalent circuit (MEC), numerical analysis, rotating machines, superconducting (SC) coils
Abstract: The present work addresses the ongoing development of a mesh-based magnetic equivalent circuit (MEC) to estimate the magnetic flux distribution in a superconducting hybrid rotating synchronous machine, superconducting (SC) rotor, and conventional stator. The MEC is to be integrated in an existing thermoelectric lumped-parameter machine model for the transient simulation of High Temperature Superconductor (HTS) field coil synchronous generator (SG) in the dq0 frame of reference. It will allow the inclusion of the magnetic flux density inside the definition of the non-linear resistance of the superconductor in addition to the already-present temperature and current. The objective is to gain further accuracy on the coupled thermal and electromagnetic behavior of superconducting hybrid machines during partial or total loss of the superconducting state. In the present work, the MEC is benchmarked against a Finite Element Model (FEM). It is shown that the MEC can provide proper magnitude of the magnetic flux density over the HTS winding achieving a good estimation of the magnetic response of the field winding by taking into account the penetration of current within the superconductor. The case study is a 100-MVA hydroelectric HTS field coil SG considering a field current ramp.
Neural Adaptive Robust Motion-Tracking Control for Robotic Manipulator Systems
Daniel Galván Pérez1 , Hugo Yañez Badillo2 , Francisco Beltrán Carbajal3 , Iván de Jesús Rivas Cambero1 , Antonio Favela Contreras4 , Rubén Tapia Olvera5
1 Universidad Politécnica de Tulancingo, Departamento de Posgrado
2 Tecnológico Nacional de México, Tecnológico de Estudios Superiores de Tianguistenco
3 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
4 Tecnológico de Monterrey, Escuela de Ingeniería y Ciencias
5 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: active disturbance rejection; artificial neural networks; laser manufacturing; manipulator robot; trajectory tracking control
Abstract: This paper deals with the motion trajectory tracking control problem based on output feedback and artificial neural networks for anthropomorphic manipulator robots under disturbed operating scenarios. This class of manipulator robots constitutes nonlinear dynamic systems subjected to disturbance torques induced mainly by work payload. Parametric uncertainty and possible dynamic modeling errors stand for other kind of disturbances that can deteriorate the efficiency and robustness of the tracking of controlled nonlinear robotic system trajectories. In fact, the presence of unknown dynamic disturbances is unavoidable in industrial robotic engineering systems. Therefore, for high-precision applications, such as laser cutting, marking, or welding, effective control schemes should be designed to guarantee adequate motion profile tracking planned on this class of disturbed nonlinear robotic system. In this context, a new adaptive robust motion trajectory tracking control scheme based on output feedback and artificial neural networks of anthropomorphic manipulator robots is presented. Three-layer B-spline artificial neural networks and time-series modeling are properly exploited in the design of novel adaptive robust motion tracking controllers for robotic applications of laser manufacturing. In this way, dependency on detailed nonlinear mathematical modeling of robotic systems is considerably reduced, and real-time estimation of uncertain dynamic disturbances is not required. Furthermore, several cases studies to demonstrate the motion planning tracking control robustness for a class of MIMO nonlinear robotic systems are described. blue Insights for the extension of the introduced output-feedback adaptive neural control design approach for other architecture of nonlinear robotic systems are depicted.
An Adaptive Scheme to Improve Prony’s Method Performance to Estimate Signal Parameters of Power System Oscillations
IEEE Transactions on Instrumentation and Measurement
Rubén Tapia Olvera1 , Daniel Guillen 2 , Francisco Beltrán Carbajal3 , Luis Miguel Castro González1
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 Autónoma Metropolitana, Unidad Azcapotzalco

Keywords: Adaptive order, neural networks (NNs), parameter estimation, power oscillations, Prony’s method
Abstract: This work introduces a new methodology based on neural networks (NNs) and Prony’s method to estimate the signal parameters during power oscillations related to transient phenomena caused by severe perturbations. Power system dynamic analysis becomes essential to establish reliability indices under critical conditions; these indices are commonly based on signal parameters estimated at different points throughout the power system. In this context, the proposed approach offers several advantages due to the adaptability of NNs. The proposed formulation is first analyzed with a signal model with different oscillating components. This technique is validated for a wide range of conditions, where the results show good accuracy to carry out the estimation of the signal parameters such as frequency and damping. In addition, the proposed method is validated using a multimachine power system with four synchronous generators considering different operating conditions that result in power oscillations; comparison results against the fast Fourier transform (FFT), conventional Prony’s method, matrix pencil method, and Prony combined with Haar transform are included to prove the effectiveness of the proposed approach. Quantitative indexes, which exhibit the performance of the proposal, are presented to duly demonstrate the evolution of new adaptive scheme.
Resultados experimentales del control de un sistema de teleoperación bilateral de robots con retardos variantes en el tiempo
Revista Iberoamericana de Automática e Informática industrial
Mauro Gilberto López 1 , Marco Antonio Arteaga Pérez1 , Alejandro Gutiérrez Giles2 , Emmanuel Nuño 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados
3 Universidad de Guadalajara, Centro Universitario de Ciencias Exactas e Ingeniería

Keywords: Teleoperadores bilaterales, diseño de observadores, retardos variantes en el tiempo, correspondencia cinemática retardada
Abstract: Los sistemas bilaterales de teleoperación son útiles en una amplia gama de tareas que pueden resultar peligrosas o inaccesibles para un humano. Sin embargo, cuando aparecen retardos variantes en el tiempo en el canal de comunicación, ya no se puede garantizar una transparencia perfecta. En cambio, se pueden perseguir otros objetivos de control, como la correspondencia cinemática entre los robots local y remoto. Además, dado que la mayoría de los robots disponibles comercialmente no están equipados con sensores de velocidad, para garantizar un cierto nivel de transparencia o correspondencia cinemática, el controlador no puede depender de las mediciones de velocidad. Este artículo está enfocado en presentar los resultados experimentales de un esquema robusto ante los retardos en el tiempo para manipuladores no lineales conectados a través de un canal de comunicación. Las ventajas principales del esquema propuesto son: i) no es necesario conocer los parámetros dinámicos de los manipuladores, ii) no es necesario imponer restricciones acerca del comportamiento del operador humano y de la superficie remota, iii) se obtiene una estimación de velocidades através de un filtro lineal de segundo orden, iv) un término que garantiza el seguimiento de fuerza fue agregado al esquema. Con el objetivo de mostrar el buen desempeño del esquema propuesto, se reportan un conjunto de experimentos que se han llevado a cabo entre diferentes ciudades de México utilizando Internet como canal de comunicación.
A continuous terminal sliding mode algorithm for robot manipulators: an application to force control
International Journal of Control
Lauro F. Vázquez Alberto1 , Marco Antonio Arteaga Pérez1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Super twisting algorithm; force control; robot manipulators; high friction effects
Abstract: The problem of hybrid position/force control on rigid surfaces with high friction effects is considered in this letter. The controller is based on a Continuous Terminal Sliding Mode Algorithm (CTSMA), which allows to obtain a high tracking performance for industrial robot manipulators with DC motors. When the desired trajectory corresponds to the geometric constraint of a rigid surface, then an additional PI term can be included in the control law to achieve force tracking perpendicular to the surface, while friction effects are rejected by the CTSMA, thus leading to a notorious performance improvement. To the best of the authors' knowledge this is the first time that this technique is used for this particular goal. In case the robot manipulator does not own DC motors as actuators, the algorithm can be complemented with the knowledge of the inertia matrix to make the result applicable to any kind of rigid robots. Both simulation and experimental results are presented and the outcomes are compared with a GPI control/observer approach. The Root Mean Square Errors (RMSE) are computed to show objectively the advantages of the proposed solution.
Robust Multi-Model Predictive Control via Integral Sliding Modes
IEEE Control Systems Letters
Rosalba Galván Guerra1 , Gian Paolo Incremona 2 , Leonid Fridman Golredich3 , Antonella Ferrara 4
1 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo
2 Politecnico di Milano, Informazione e Bioingegneria
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 University of Pavia, Dipartimento di Ingegneria Industriale e dell’Informazione

Keywords: Sliding mode control, model predictive control, multi-model systems, uncertain systems
Abstract: This letter presents a novel optimal control approach for systems represented by a multi-model, i.e., a finite set of models, each one corresponding to a different operating point. The proposed control scheme is based on the combined use of model predictive control (MPC) and first order integral sliding mode control. The sliding mode control component plays the important role of rejecting matched uncertainty terms possibly affecting the plant, thus making the controlled equivalent system behave as the nominal multi-model. A min-max multi-model MPC problem is solved using the equivalent system without further robustness oriented add-ons. In addition, the MPC design is performed so as to keep the computational complexity limited, thus facilitating the practical applicability of the proposal. Simulation results show the effectiveness of the proposed control approach.
Editorial: Machine Learning and Deep Learning for Physiological Signal Analysis
Frontiers in Physiology
Rajesh Kumar Tripathy 1 , Mario Roberto Arrieta Paternina2 , José Antonio De la O Serna 3
1 Birla Institute of Technology and Science,
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica

Keywords: Machine learning, deep learning, physiological signals, accuracy, sensitivity
Abstract: The machine learning (ML) and deep learning (DL) methods play an essential role in developing automated diagnostic systems for the accurate detection of various diseases using physiological signals (Yin et al., 2017). These methods are also used for emotion recognition, cognitive workload assessment, brain-machine interface, and other applications using physiological signals (Varshney et al., 2021; Maheshwari et al., 2021; Radhakrishnan et al., 2021; Tripathy et al., 2018). The advances of wearable technology and the internet of things (IoT) enable real-time monitoring of patients’ health status using physiological sensor data (Zhou et al., 2020). The ML and DL models are deployed on these intelligent healthcare systems for automated and real-time patient monitoring. The goal of this special issue on Machine Learning and Deep Learning of Physiological Signal Analysis was to disseminate the articles related to the (a) application of ML and DL for cardiovascular signal processing, (b) application of ML and DL for neural signal processing, (c) the use of ML and DL for affective computing, (d) application of ML and DL to bioinformatics, (e) ML and DL applications to human gait analysis and fatigue monitoring. In this special issue, ten papers have been submitted, and each of these papers was reviewed by at least two reviewers. Based on the reviewer’s feedback, seven papers are published in this special issue of the Frontiers in Physiology journal.
Power system coherency recognition and islanding: Practical limits and future perspectives
IET Energy Systems Integration
Harold R. Chamorro 1 , Edgar Gómez Díaz2 , Mario Roberto Arrieta Paternina3 , Manuel A. Andrade 2 , Emilio Barocio 4 , José L. Rueda 5 , Francisco González Longatt6 , Vijak K. Sood 7
1 KTH Royal Institute of Technolog,
2 Universidad Autónoma de Nuevo León,
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad de Guadalajara, CUCEI
5 Delft University of Technology, Department of Electrical Sustainable Energy
6 University of South-Eastern Norway,
7 Ontario Tech University,

Abstract: Electrical power systems are continuously upgrading into networks with a higher degree of automation capable of identifying and reacting to different events that may trigger undesirable situations. In power systems with decreasing inertia and damping levels, poorly damped oscillations with sustained or growing amplitudes following a disturbance may eventually lead to instability and provoke a major event such as a blackout. Additionally, with the increasing and considerable share of renewable power generation, unprecedented operational challenges shall be considered when proposing protection schemes against unstable electro-mechanical (e.g. ringdown) oscillations. In an emergency situation, islanding operations enable splitting a power network into separate smaller networks to prevent a total blackout. Due to such changes, identifying the underlying types of oscillatory coherency and the islanding protocols are necessary for a continuously updating process to be incorporated into the existing power system monitoring and control tasks. This paper examines the existing evaluation methods and the islanding protocols as well as proposes an updated operational guideline based on the latest data-analytic technologies.
Fast hierarchical coordinated controller for distributed battery energy storage systems to mitigate voltage and frequency deviations
Applied Energy
Gabriel E. Mejía Ruiz1 , Mario Roberto Arrieta Paternina1 , Felix Rafael Segundo Sevilla2 , Petr Korba 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Zurich University of Applied Sciences,

Keywords: Coordinated control, Eigensystem realisation algorithm, Battery energy storage systems, Hierarchical control, Distributed energy resources
Abstract: This paper proposes a novel hierarchical optimal control framework to support frequency and voltage in multi-area transmission systems, integrating battery energy storage systems (BESSs). The design is based on the coordinated active and reactive power injection from the BESSs over conventional synchronous generator-based control for fast and timely mitigation of voltage and frequency deviations. The principle of this new idea is to use two hierarchical schemes, one physical and one logical. The objective of the first scheme prioritises the power injection from the BESSs installed in the area where a contingency occurs, consequently reducing the disturbance of the dynamics in the neighbouring areas. In the second scheme, operational rules for aggregated BESSs in each are incorporated, increasing the safety of the asset. The proposed approach exploits the advantages of time-synchronised measurements, the eigensystem realisation algorithm (ERA) identification technique, the optimal linear quadratic Gaussian (LQG) controllers and a new aggregating agent that coordinates the power injection of BESSs in a hierarchical and scalable scheme to precisely regulate frequency and voltage of modern transmission grids, increasing their reliability and stability. The feasibility and robustness of the proposal is demonstrated using simulated scenarios with significant load changes and three-phase, three-cycle faults on a modified Kundur-system with four interconnected areas, mitigating frequency and voltage contingencies in less than 450 ms.
Acceleration of the order of convergence of a family of fractional fixed-point methods and its implementation in the solution of a nonlinear algebraic system related to hybrid solar receivers
Applied Mathematics and Computation
Anthony Torres Hernández1 , Fernando Brambila Paz1 , Rodrigo Montúfar Chaveznava2
1 Universidad Nacional Autónoma de México, Facultad de Ciencias
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fractional operators, Group theory, Order of convergence, Fractional calculus of sets
Abstract: This paper presents one way to define an uncountable family of fractional fixed-point methods through a set of matrices that can generate a group of fractional matrix operators, as well as one way to define groups of fractional operators that are isomorphic to the group of integers under the addition, and shows one way to classify and accelerate the order of convergence of the family of proposed iterative methods, which may be useful to continue expanding the applications of the fractional operators. The proposed method to accelerate the order of convergence is used in a fractional iterative method, and with the obtained method are solved simultaneously two nonlinear algebraic systems that depend on time-dependent parameters, and that allow obtaining the temperatures and efficiencies of a hybrid solar receiver. Finally, two uncountable families of fractional fixed-point methods are presented, in which the proposed method to accelerate convergence can be implemented.
Management Model for University-Industry Linkage Based on the Cybernetic Paradigm: Case of a Mexican University
International Journal of Information Technologies and Systems Approach
Yamilet Nayeli Reyes Morales1 , Javier Suárez Rocha1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: This paper presents a management model that describes the attributions of the different actors that work together in the realization of university-industry linkage projects, as well as the relations between these actors. The construction of the model was carried out based on the systemic and cybernetic approaches. The Management Model for University-Industry Linkages was used in the implementation of seven projects, which allowed the validation of its potential as a tool to monitor and regulate the process of project execution, guaranteeing the satisfactory fulfillment of the established objectives. One of the limitations of the model is that its functional structure responds to the management of the institution's linkage projects only for the knowledge field of engineering and that these projects are carried out through a system or organization linking the university with the industry, which can lead to duplication of activities or lack of coordination between the areas that carry out linking activities for the entire educational institution.
Experiencias y propuestas para la enseñanza a distancia de dos asignaturas optativas, del área de materiales, a estudiantes de ingeniería
Arturo Barba Pingarrón1 , Dayi Gilberto Agredo Díaz2 , Jesús Rafael González Parra1 , Alba Covelo Villar1 , Miguel Ángel Hernández Gallegos1 , Raúl Valdéz Navarro1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional de Colombia, Facultad de Ingeniería

Keywords: enseñanza de materiales; enseñanza a distancia; recursos didácticos; aprendizaje significativo
Abstract: La enseñanza, en pandemia, se ha modificado y los procesos a distancia han tomado un lugar importante. Este trabajo describe que estrategias se generaron para conseguir un aprendizaje con resultados apropiados, bajo estas condiciones. Se relatan diversas experiencias y un grupo de propuestas para estudiantes de la carrera de ingeniería mecánica, de dos asignaturas optativas (Ingeniería de Superficies, Temas Selectos de Materiales), en enseñanza a distancia. Se describen los recursos utilizados, las formas de evaluación empleadas y se presentan evidencias del aprendizaje alcanzado. Con ello, se consiguió una participación creciente de los alumnos y un adecuado nivel de aprendizaje. El propósito de este trabajo es contribuir a la labor docente de profesores en la enseñanza de Materiales, en educación a distancia, compartiendo las alternativas descritas y usadas en estas dos asignaturas, lo cual, en alguna medida, puede trasladarse a otras y realizar una reflexión sobre sus virtudes y limitaciones.
Paleomagnetism of the La Mora Formation: Late Triassic-Late Jurassic paleolatitudinal record for Southern Mexico and its Gondwanan disconnection
International Geology Review
Cecilia I. Caballero Miranda1 , Bernardo I. García Amador1 , Luis M. Alva Valdivia1 , Gilberto Silva Romo2 , Arnaldo Hernández Cardona1 , Alam Israel De la Torre González2 , Rosario Peralta Salazar3
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Petroanalisis, S.A. de C.V.,

Keywords: Red beds paleomagnetism, Late Triassic-Late Jurassic Pangea, AMS paleo-fluvial system, Mixteca terrane, peri-Gondwanan blocks
Abstract: A comprehensive paleomagnetic study of the La Mora Formation fluvial sediments, presumably deposited during the Late Triassic-Early Jurassic, over the Mixteca terrane, allows us to document the most likely Early Mesozoic paleoposition of the Acatlán-Oaxaquia block among the mosaic of peri-Gondwanan blocks just before and during Pangea break-up. The oxide microscopy and the rock magnetic studies confirm that the magnetic carrier is titanomagnetite, hematite partially to almost totally replacing titanomagnetite (maghemite), and pigmentary hematite, in varying proportions related to dominant facies along the sedimentary sequence. Paleomagnetic results indicate that chemical remanent magnetization was acquired at during a time-lapse from the last steps of deposition to the burial and weakly deformation stage during the Late Jurassic (ca. 160 Ma). The mean paleolatitudes in flattening, unflattening, and geographic coordinate inclinations are: 7.6°N ± 1.6°, 9.8°N ± 1.7° and 11.1°N ± 1.6°, in comparison to the current latitude that is 18°N. However, a southern paleoposition of the La Mora Formation for the Late Triassic, is indicated from detrital zircon provenance ages from Amazonian craton sources, suggesting that the Acatlán-Oaxaquia block was juxtaposed to the northwestern Gondwana corner (i.e. NW South America), close to 7°S ± 2°. Therefore, we reported ca. 1800 ± 220 km of northward transport of the Acatlán-Oaxaquia block during the Late Triassic to Late Jurassic Pangea break-up. Last, the magnetic anisotropy susceptibility (AMS) indicates a primary origin magnetic fabrics with a slight syn-sedimentary tectonic overprint that agree with the Amazonian westward paleo-fluvial system.
A biomass waste evaluation for power energy generation in Mexico based on a SWOT & Fuzzy-logic analysis
International Journal of Sustainable Energy Planning and Management
Mariana Hernández Escalante1 , Cecilia Martín del Campo1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Waste, Bioenergy, SWOT analysis, Fuzzy logic, Indicative planning.
Abstract: Power energy generation in Mexico based on bioenergy is currently insignificant. However, the potential for taking advantage of biomass resources in the country is considerable. This article aims to evaluate the use of biomass waste for the Mexican energy transition in the near future. The methodology starts by identifying sites with biomass waste and establishing the conversion processes needed to produce electricity for each type of biomass. A SWOT analysis was implemented to define the criteria for evaluating all options on the same basis. The opinion of experts in energy systems was collected to assign the priority to each criterion. A fuzzy-logic inference system was formulated to assess the options based on the quality of their attributes. The output obtained from the fuzzy analysis is a sustainability prioritisation of all options. We analysed a case study for the Baja California Sur (BCS) region, and the results show the prioritisation ranking of 24 alternatives regarding the sustainable use of bioenergy in the region and we made a proposal of an indicative plan to introduce bioenergy in the region from now until 2032. If the indicative plan were implemented, 61% of the power demand of BCS could be covered with bioenergy by 2032.
The late Holocene Nealtican lava-flow field, Popocatépetl volcano, central Mexico: Emplacement dynamics and future hazards
The Geological Society of America Bulletin
Israel Ramírez Uribe1 , Claus Siebe 1 , Magdalena Oryaëlle Chevrel2 , Dolors Ferres 3 , Sergio Salinas 4
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Université Clemont Auvergne, Laboratoire Magmas et Volcans
3 Universidad Nacional Autónoma de México, Escuela Nacional de Ciencias de la Tierra
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: Popocatépetl, one of the most hazardous volcanoes worldwide, poses significant threats for nearby populations in central Mexico. Therefore, it is important to reconstruct its eruptive history, including estimates of lava-flow emplacement times and their rheological properties. These studies define possible future eruptive scenarios and are necessary to mitigate the risk. Stratigraphic studies of the cal 350–50 B.C. Lorenzo Plinian pumice sequence indicate that effusive activity (Nealtican lava-flow field) occurred shortly after explosive activity, reflecting drastic changes in the eruptive dynamics. It was likely due to the efficient degassing of the magma during the Plinian phase and a decrease of magma ascent and decompression rates. Magma mixing, fractional crystallization, and a minor crust assimilation are the processes controlling the differentiation of the Nealtican lavas. We used lava chemical and mineralogical composition to estimate lava-flow viscosities, and used high-resolution elevation data to estimate emplacement times. Results indicate that lava viscosities of andesites and dacites ranged from 109 to 1012 Pa·s and emplacement durations were between ~1 and ~29 years, depending on the flow unit and morphological method employed. Considering the entire volume of emitted lava (4.2 km3) and a mean output rate of ~1 m3/s to ~15 m3/s, we estimated that the effusive phase that produced the Nealtican lava-flow field may have lasted ~35 years. This eruption had a considerable impact on pre-Hispanic settlements around the volcano, whose population exodus and relocation probably contributed to the rise of important cities in central Mexico, such as Teotihuacán and Cholula.
Modelamiento y simulación de una planta de recuperación de plata con tiourea
Rubén Robles Ramos1 , Mauricio Joaquín Reyna Robledo1 , Dandy Calla Choque1 , José Enrique Santos Jallath1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Modelamiento, Simulación, Plata, Tanques de lixiviación
Abstract: Algunos residuos generados en operaciones metalúrgicas tienen elementos metálicos de interés, por lo que pueden ser reprocesados para darle un valor adicional a la operación. Este trabajo presenta el modelamiento y simulación de tanques de lixiviación para la recuperación de plata con tiourea y oxalato a partir de jarositas que son uno de los principales desechos del procesamiento del zinc. Se usaron modelos de primer orden y se seleccionó el de mejor ajuste para la evaluación de la velocidad de lixiviación en tanques con agitación continua (CSTR). Finalmente se presentan los resultados obtenidos en la simulación del proceso con ayuda del software Matlab-Simulink® por medio de bloques de subsistemas.
Trajectory tracking control for autonomous underwater vehicle with disturbances and input saturation based on contraction theory
Ocean Engineering
Caipeng Ma 1 , Yu Tang Xu2 , Ming Lei 1 , Dapeng Jiang 1 , Wanzhen Luo 1
1 Sun Yat-Sen University, School of Ocean Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Trajectory tracking, Extended state observer, Actuator saturation, Singular perturbation system, Contraction theory
Abstract: Autonomous underwater vehicle (AUV) is a complex nonlinear system and its control is accompanied by various challenges. This paper focuses on the three dimensional (3D) trajectory tracking control of a fully-actuated AUV in the presence of model uncertainties, unmeasured velocity, time-varying external disturbance and input saturation. First, taking the model uncertainties and external disturbances as the total disturbances, an extended state observer (ESO) is designed to estimate the unmeasured velocity and total disturbances. Then, the saturated controller based on contraction theory and its application in singular perturbation system (SPS) is obtained so that the AUV tracks the desired trajectory and avoids exceeding the limit of the actuator. The estimation error, tracking error and the error between the ideal controller and the actual controller are analyzed by contraction theory, and the explicit bounds of these errors are given. At last, comparative numerical simulations are provided to show the effectiveness of the ESO and the advantages of the saturated controller.
Friction factor analysis for a nanofluid circulating in a microchannel filled with a homogeneous porous medium
Fluid Dynamics Research
Francisco Fernando Hernández Figueroa1 , Federico Méndez Lavielle1 , José Joaquín Lizardi Del Ángel2 , Ian Guillermo Monsivais Montoliu1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: friction factor, porous media, nanofluids, microchannels
Abstract: This work presents the numerical solution for different velocity profiles and friction factors on a rectangular porous microchannel fully saturated by the f low of a nanofluid introducing different viscosity models, including one nanofluid density model. The Darcy-Brinkman-Forchheimer equation was used to solve the momentum equation in the porous medium. The results show that the relative density of the fluid, the nanoparticle diameters and their volumetric concentration have a direct influence on the velocity profiles only when the inertial effects caused by the presence of the porous matrix are important. Finally, it was found that only viscosity models that depend on temperature and nanoparticle diameter reduce the friction factor by seventy percent compared to a base fluid without nanoparticles; furthermore, these models show a velocity reduction of even ten percent along the symmetry axis of the microchannel.
Spatial Fractional Darcy’s Law on the Diffusion Equation with a Fractional Time Derivative in Single-Porosity Naturally Fractured Reservoirs
Fernando Alcántara López1 , Carlos Fuentes 2 , Rodolfo Gabriel Camacho Velázquez3 , Fernando Brambila Paz1 , Carlos Chávez 4
1 Universidad Nacional Autónoma de México, Facultad de Ciencias
2 Instituto Mexicano de Tecnología del Agua,
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Autónoma de Querétaro, Centro de Investigación del agua

Keywords: Weyl fractional derivative; Caputo fractional derivative; fractal porous media; naturally fractured reservoir
Abstract: Due to the complexity imposed by all the attributes of the fracture network of many naturally fractured reservoirs, it has been observed that fluid flow does not necessarily represent a normal diffusion, i.e., Darcy’s law. Thus, to capture the sub-diffusion process, various tools have been implemented, from fractal geometry to characterize the structure of the porous medium to fractional calculus to include the memory effect in the fluid flow. Considering infinite naturally fractured reservoirs (Type I system of Nelson), a spatial fractional Darcy’s law is proposed, where the spatial derivative is replaced by the Weyl fractional derivative, and the resulting flow model also considers Caputo’s fractional derivative in time. The proposed model maintains its dimensional balance and is solved numerically. The results of analyzing the effect of the spatial fractional Darcy’s law on the pressure drop and its Bourdet derivative are shown, proving that two definitions of fractional derivatives are compatible. Finally, the results of the proposed model are compared with models that consider fractal geometry showing a good agreement. It is shown that modified Darcy’s law, which considers the dependency of the fluid flow path, includes the intrinsic geometry of the porous medium, thus recovering the heterogeneity at the phenomenological level.
Accurate Analytical Model and Evaluation of Wi-Fi Halow Based IoT Networks under a Rayleigh-Fading Channel with Capture
Hamid Taramit 1 , José Jaime Camacho Escoto2 , Javier Gómez 2 , Luis Orozco Barbosa3 , Abdelkrim Haqiq 4
1 Hassan First University of Settat, Faculty of Sciences and Techniques
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad de Castilla-La Mancha, Albacete Research Institute of Informatics
4 , Faculty of Sciences and Techniques

Keywords: performance evaluation; renewal theory; stochastic process; IEEE 802.11ah; RAW mechanism; capture effect; Internet of things
Abstract: The IEEE 802.11ah standard, marketed as Wi-Fi Halow, introduces a new channel access mechanism called the Restricted Access Window (RAW), aiming to provide connectivity for the Internet of Things (IoT) applications over broad areas. RAW aspires to alleviate the contention by splitting the channel access into periods and allocating each period to a given group of stations. This paper develops an analytical framework based on Probability and Renewal theories for modeling and evaluating an IEEE 802.11ah-based network implementing the RAW mechanism. We consider a Rayleigh-fading channel with the presence of the capture effect: a realistic scenario for IoT networks deployed in dense urban environments. Considering a single-hop scenario of stations randomly distributed around an Access Point (AP) and the power attenuation of transmitted packets, we model the channel access under capture awareness. As the RAW mechanism presents a time-limited contention for channel access, we develop a counting process that tracks transmissions up to the end of the contention time interval. Henceforth, we evaluate the network performance in terms of throughput. We meticulously validate the derived analytical results through extensive campaigns of discrete-event simulations. Our study evaluates the impact of different parameters on the overall performance, including the contention time, the number of stations, the number of groups, and the capture threshold. We henceforth study the impact of the capture effect on enhancing the network performance under the grouping feature introduced by the RAW mechanism. This work contributes to developing an analytical modeling framework to evaluate the performance of time-limited random access mechanisms accurately and can be an excellent basis for proposing practical scheduling algorithms to configure the RAW mechanism under non-ideal channel conditions.
PPAASS: Practical Power-Aware Duty Cycle Algorithm for Solar Energy Harvesting Sensors
IEEE Access
Ariel Cinco Solis1 , José Jaime Camacho Escoto2 , Luis Orozco Barbosa3 , Javier Gómez 2
1 Universidad Nacional Autónoma de México, Instituto de Investigación en Matemáticas Aplicadas y Sistemas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad de Castilla-La Mancha, Albacete Research Institute of Informatics

Keywords: Energy harvesting, energy management, green IoT, Internet of Things, solar energy
Abstract: Energy-harvesting sensor networks promise unlimited operation throughout time, benefiting ongoing monitoring applications. However, most energy sources, such as sunlight, vary over time and do not guarantee constant power delivery to a device. In addition, these devices lack a battery with the necessary capacity to store enough energy to operate when harvesting is impossible. Thus, managing energy consumption becomes essential for any device to function correctly. This article proposes PPAASS (Practical Power-Aware Algorithm for Solar Sensors), a novel algorithm that allows devices to change their duty cycle to maximize the use of harvested energy based on the device’s battery backup level and solar irradiance predictions. The algorithm was evaluated through simulations performed in Python and with different solar irradiance conditions depending on the season of the year. PPAASS shows a higher average duty cycle than other algorithms in the literature while maintaining a few changes in the duty cycle, which makes it ideal for constant monitoring applications. Furthermore, the implementation of the algorithm shows that the real-time duty cycle adaptation allows a device to react quickly to energy harvesting prediction failures and take full advantage of all the harvested energy. Our experimental results showed that PPAASS provided devices with power availability at all times while reducing to a maximum of 15% the time the system did not harvest all the solar energy because the battery was full.
12 Years of Area Variation by the Drygalski Ice Tongue as Measured With COSMO-SkyMed
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Miguel Moctezuma Flores1 , Flavio Parmiggiani 2 , Lorenzo Guerrieri 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Institute of Atmospheric Sciences and Climate, Bologna

Keywords: Ice, image segmentation, remote sensing, synthetic aperture imaging
Abstract: One important coastal polynya around Antarctica is Terra Nova Bay (TNB) polynya. Its formation and persistence are due to the combined effect of katabatic winds, regional ice conditions, and the Drygalski Ice Tongue (DIT). The combined effect of these elements arranges a delicate balance in TNB. To evaluate the interacting elements, we focused our attention on the DIT, one of the largest ice tongues in Antarctica. The DIT is a 70-km long tongue, which juts out like a pier from the icy land into northern McMurdo Sound of Antarctica's Ross Dependency. The analysis presented in this article was carried out using Cosmo-SkyMed (CSK) images. The methodology developed for the analysis consists of three steps: 1) DIT shape enhancement, 2) fuzzy Bayesian segmentation which associates the analyzed set of pixels with a binary label field, and 3) parametric representation of the shape of the DIT to compare the area of the ice tongue as it was 12 years ago and as it is today. The computed mean value of the DIT surface velocity was 703 m y -1 . To estimate the closeness of the derived parameter to the true value, using a statistical approach, the 95% confidence interval for the true mean value is 703 ± 4.236 m y -1 . Our analysis confirms a trend of advance. That is, after the significant calving events of the tongue in 2005 and 2006, the DIT has resumed its normal growth, and its length has increased by 12% in the last 12 years.
Enhancing Grid Integration and Design of Low Speed PMSGs by Exploiting SRF-PLL-based Sensorless Control and Holistic Modeling
IEEE Transactions on Energy Conversion
Gabriel E. Mejía Ruiz1 , José Manuel Ramos Guerrero1 , Mario Roberto Arrieta Paternina1 , Javier De la Cruz Soto2 , Alejandro Zamora Méndez3 , Paul Pedraza 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Nacional de Electricidad y Energias Limpias, Gerencia de Control, Electrónica y Comunicaciones
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
4 Universidad del Estado de Morelos,

Keywords: PMSG, wind turbine, back to back, phase locked loop, mechanical design
Abstract: This paper proposes a holistic co-design framework with a low-cost approach for a permanent magnet synchronous generator (PMSG) that enables to optimizes both the electromagnetic and mechanical design, in conjunction with the injection of the maximum available power towards the power grid through a controlled electronic back-to-back converter. The proposed sensorless controller includes a hybrid PLL with a dynamically adjustable tabulated gains system and a feedforward frequency estimator. These add-ons allow to precisely track the speed and angle of the rotor shaft for near-zero speeds. This methodology includes the development of analytical models for the structural, magnetic and electrical components. The efficiency and performance of the machine and controller is verified by simulation under different load conditions and high angular speed variability of a 1.5kW scale prototype in JMAG® and Matlab & Simulink™ environments, reaching an efficiency of 80%.
Cover Image
Journal of Applied Polymer Science
Albanelly Soto Quintero1 , Patricia González Alva1 , Alba Covelo Villar1 , Miguel Ángel Hernández Gallegos1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: The cover image created by Albanelly Soto-Quintero and colleagues shows fluorescence micrographs of HaCat cell adhesion on PVA/SA scaffolds mats prepared with varying concentrations of SA (3.5, 4.0, and 5.0 wt%). Many cells can be seen attached to the surface of the mats after 7 days of culture. Interestingly, a slight change in the SA concentration changes the pattern of cell adhesion. Cells attached to the 3.5 wt% SA scaffolds show well-defined round clusters, whereas the 4.0 wt% and 5.0 wt% SA show a homogenous distribution over the surface while maintaining their characteristic cuboidal shape.
Caracterización estructural de recubrimientos químicos Ni-P-Al2O3 tratados térmicamente
Tópicos de Investigaión en Ciencias de la Tierra y Materiales
Arturo Barba Pingarrón1 , Alba Covelo Villar1 , Miguel Ángel Hernández Gallegos1 , Dayi Gilberto Agredo Díaz2 , Raúl Valdéz Navarro1 , Jesús Rafael González Parra1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional de Colombia, Facultad de Ingeniería

Keywords: Recubrimientos químicos compuestos de Niquelado químico, Tratamiento térmico, Endurecimiento por precipitación, Difracción de Rayos X, Microdureza
Abstract: En este trabajo se presentan los resultados del estudio de los cambios microestructurales que ocurren en recubrimientos químicos de níquel sobre un sustrato de aluminio, sin partículas y con la adición de partículas de óxido de aluminio, tal como se depositan y posteriores a la aplicación de un tratamiento térmico a 300 °C y 400 °C, durante una hora. La caracterización de los revestimientos obtenidos se realizó mediante microscopía electrónica de barrido, microscopía interferométrica, microdureza, microanálisis y difracción de rayos X. Los recubrimientos experimentan, luego del tratamiento térmico aplicado, un cambio estructural que los lleva, de una condición inicial amorfa a una condición cristalina, acompañado de un proceso de endurecimiento por precipitación que provoca un incremento de la microdureza de los recubrimientos. Se observa, asimismo, que la presencia de las partículas de óxido de aluminio, en la proporción empleada, no tiene efecto relevante en las transformaciones estructurales de los depósitos, respecto al revestimiento sin partículas.
Dynamic mathematical heat transfer model for two-phase flow in solar collectors
Case Studies in Thermal Engineering
Heriberto Sánchez Mora1 , Sergio Quezada García2 , Marco A. Polo Labarrios2 , Ricardo Isaac Cázares Ramírez3 , Alejandro Torres Aldaco3
1 Instituto Politécnico Nacional,
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma Metropolitana, Unidad Iztapalapa

Keywords: Heat transfer fluid, Water, Parabolic trough collector, Thermal efficiency
Abstract: In the present study, a dynamic heat transfer model is developed for two-phase flow through the absorber tube of linear solar collectors, where the heat transfer fluid is water. The model considers that thermophysical properties, such as viscosity, thermal conductivity, densities, and specific heat, depend on temperature; this dependency is reflected in the value of the convective heat transfer coefficient. The governing partial differential equations for the fluid are solved using the finite difference method in an explicit scheme, the heat transfer equation for the absorber tube uses an implicit scheme, whose solution is implemented in C++ compiler. The model is validated with experimental data from a solar collector using a Solar Fresnel Reflector type, with an error related to the steam quality lower than 4.28% at the outlet of the collector and a better fit with the temperature profile through the collector in comparison with previous studies. The results show that as the phase change occurs, increasing the quality of steam in the absorber tube, the collector efficiency decreases. This is due to that the convective heat transfer coefficient of the absorber decreases, since the thermophysical properties of the liquid-steam mixture do not favor heat transfer.
Partitions among elastic waves for dynamic surface loads in a layered medium
Geophysical Journal International
José Piña Flores1 , Martín Cárdenas Soto1 , Antonio García Jerez2 , Francisco José Sánchez Sesma3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de Almería, Departamento de Química y Física
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Body waves, Surface waves and free oscillations, Wave propagation
Abstract: The relationship between the Green's function and the average correlations of the elastic displacements within a diffuse field has been firmly established. The energies of horizontal and vertical motion in such a field are proportional to the imaginary part of the corresponding diagonal components of the Green's tensor for coincident source and receiver. Given this remarkable connection, we examine the partitions of elastic waves due to dynamic horizontal and vertical surface loads in a layered elastic media. The elastic radiation characteristics for horizontally layered media are much more complicated than for the homogeneous half-space. While the corresponding power partitions of the different types of waves in a half-space do not vary with respect to frequency, even in an elastic medium consisting of layers over a half-space, the modal structure shows strong variations in the frequency, mainly around the main peak and the minimum of the horizontal-to-vertical spectral ratio. Using a test model with a moderately high impedance contrast, we find that most of the energy density of the horizontal displacements is concentrated in the fundamental mode of the Love waves, reaching ~80 per cent of the power in the horizontal components. The vertical displacement of the P-SV body waves reaches a maximum of ~85 per cent, while the fundamental mode of Rayleigh waves reaches a maximum of ~99 per cent of the available power in the vertical motion. With this analysis, it is possible to analyze the multimodal effects in the dispersion diagrams and explicitly relate the partition of the energy density with the dispersion curves and the horizontal-to-vertical spectral ratio under the diffuse field assumption.
Optimization of Y3Fe5O12 based layered structures for quasi-optic spin wave elements
Journal of Magnetism and Magnetic Materials
José R. Fragoso Mora1 , Oleg Kolokoltsev 1 , César L. Ordoñez Romero2 , Naser Qureshi 1 , Alexander Martynyuk 3 , María del Carmen Horrillo 4 , Daniel Matatagui 4
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
2 Universidad Nacional Autónoma de México, Instituto de Física
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituto de Tecnologías Físicas y de la Información,

Keywords: Yttrium iron garnet, Spin waves, Losses, Magnonics, Multilayer magnetic structure
Abstract: We present theoretical and experimental results on the losses and confinement of spin waves (SW) in a Ferromagnetic/Normal Metal/Air/Ferrite multilayer structure. The above structure can be used for the creation of a desired topology of static magnetic field in a thin ferrite film, used as SW waveguide. It is shown that a screening Normal Metal (NMe) layer, inserted between SW waveguide and ferromagnetic (FM) layer, significantly decreases the SW losses caused by a lossy FM. It is also shown that the SW amplitude increases within the air gap (d) between a Ferrite film and NMe layer, when the gap satisfies the relation kd = 1, where k is SW wavenumber. The power flow density at Ferrite/Air interface is maximal when d is equal to a quarter wavelength of SW.
Damping coefficient by long waves—viscoelastic mud–current interaction
Physics of Fluids
A. Quesada Torres1 , Eric Gustavo Bautista Godínez1 , Federico Méndez Lavielle2
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Newtonian fluids, Fluid mechanics, Equations of fluid dynamics, Viscoelasticity, Mathematical modeling, Shear modulus, Hydrodynamics, Internal waves, Vector fields
Abstract: In this work, we study the damping of long linear waves propagating on a thin mud layer, which obeys a viscoelastic behavior, in the presence of a marine current; two cases are considered: (1) a current traveling in an opposite way to the wave propagation and (2) in the same way to the wave propagation. We obtain an asymptotic solution to the dimensionless governing equations, which allows identifying the competition between the different mechanisms involved to gain insight into the physics by which coastal mud responds to water waves. To determine the shear stresses into the viscoelastic mud, we have used the well-known Maxwell rheological model. At the interface watermud, we assume the presence of a small Stokes’ layer, and this condition allows us to consider the continuity of shear stresses and velocities at the interface. The effects of the mud physical parameters as well as the hydrodynamics impact of the water waves on the damping coefficient, fluid velocities, and shear stresses and on the free surface elevation are analyzed. The results show that the maximum value of the damping coefficient occurs when the mud thickness is of the same order of magnitude as the Stokes’ layer and for increments of the current magnitude traveling in an opposite way to the wave propagation. The asymptotic solution is compared with solutions reported in the specialized literature and the results adjust properly.
Technical Considerations for the Conformation of Specific Competences in Mechatronic Engineers in the Context of Industry 4.0 and 5.0
Eusebio Jiménez López1 , Francisco Cuenca Jiménez2 , Gabriel Luna Sandoval3 , Francisco Javier Ochoa Estrella4 , Marco Antonio Maciel Monteón3 , Flavio Muñoz 4 , Pablo Alberto Limón Leyva5
1 Universidad Tecnológica del sur de Sonora, Departamento de Investigación y Desarrollo
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Estatal de Sonora, Departamento de Ingeniería Industrial y Manufactura
4 Tecnológico Nacional de México, Instituto Superior Técnico de Cajeme
5 Instituto Tecnológico de Sonora, Departamento de Electromecánica

Keywords: Industry 4.0; competency-based education; cyber-physical systems; specific competencies; engineering education
Abstract: The incursion of disruptive technologies, such as the Internet of Things, information technologies, cloud computing, digitalization and artificial intelligence, into current production processes has led to a new global industrial revolution called Industry 4.0 or Manufacturing 4.0. This new revolution proposes digitization from one end of the value chain to the other by integrating physical assets into systems and networks linked to a series of technologies to create value. Industry 4.0 has far-reaching implications for production systems and engineering education, especially in the training of mechatronic engineers. In order to face the new challenges of the transition from manufacturing 3.0 to Industry 4.0 and 5.0, it is necessary to implement innovative educational models that allow the systematic training of engineers. The competency-based education model has ideal characteristics to help mechatronic engineers, especially in the development of specific competencies. This article proposes 15 technical considerations related to generic industrial needs and disruptive technologies that serve to determine those specific competencies required by mechatronic engineers to meet the challenges of Industry 4.0 and 5.0.
Barrier Function-Based Adaptive Lyapunov Redesign for Systems Without A Priori Bounded Perturbations
IEEE Transactions on Automatic Control
Christopher D. Cruz Ancona1 , Manuel A. Estrada 1 , Leonid Fridman Golredich1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Adaptive control, barrier function, Lyapunov redesign, sliding modes, uncertain systems
Abstract: The problem of an adaptive Lyapunov redesign is revisited for a class of systems without a priori knowledge of the function majoring nonlinear uncertainties and disturbances. An adaptive barrier function-based gain for unit control is proposed, ensuring an arbitrary a priori predefined uniform ultimate bound for solutions despite the presence of uncertainties and disturbances. The usage of positive semi-definite barrier function generates a continuous control signal adjusting the chattering, when the perturbations are decreasing to zero.
Assessment of Cracking in Masonry Structures Based on the Breakage of Ordinary Silica-Core Silica-Clad Optical Fibers
Applied Sciences
Sergei Khotiaintsev 1 , Volodymyr Timofeyev 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Faculty of Electronics

Keywords: structural health monitoring; seismic assessment; detection of structural cracks; masonry buildings; optical fiber; distributed optical fiber sensors
Abstract: This paper presents a study on the suitability and accuracy of detecting structural cracks in brick masonry by exploiting the breakage of ordinary silica optical fibers bonded to its surface with an epoxy adhesive. The deformations and cracking of the masonry specimen, and the behavior of pilot optical signals transmitted through the fibers upon loading of the test specimen were observed. For the first time, reliable detection of structural cracks with a given minimum value was achieved, despite the random nature of the ultimate strength of the optical fibers. This was achieved using arrays of several optical fibers placed on the structural element. The detection of such cracks allows the degree of structural danger of buildings affected by earthquake or other destructive phenomena to be determined. The implementation of this technique is simple and cost effective. For this reason, it may have a broad application in permanent damage-detection systems in buildings in seismic zones. It may also find application in automatic systems for the detection of structural damage to the load-bearing elements of land vehicles, aircraft, and ships.
Bi-Homogeneous Observers for Uncertain 2-DOF Mechanical Systems
IEEE Control Systems Letters
Oscar Texis Loaiza1 , René Meléndez 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, homogeneity in the bi-limit, predefined-time convergence, observers for nonlinear systems.
Abstract: A global, bi-homogeneous, observer for a class of 2-DOF mechanical systems with Coriolis and centrifugal forces, dry and viscous frictions and non-vanishing bounded uncertainties/perturbations is proposed, ensuring predefined upper bound of convergence time.
Power generation cell driven by osmotic pressure in microchannels with hydrophobic surfaces and viscoelectric effects
Journal of Physics D: Applied Physics
Guillermo Sánchez 1 , Federico Méndez Lavielle1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Electric power generation, streaming potential, viscoelectric effect, hydrophobic surfaces, semi-impermeable membrane
Abstract: A theoretical study that explores power generation via streaming potential and osmotic gradients is proposed. The system is compounded by an osmotic membrane that has different saline concentrations on each side. This concentration gradient promotes a volumetric flux rate inside a microchannel with parallel plates whose surfaces are made of modified hydrophobic fumed silica, thus, the no-slip condition is no longer sustained. Aside from these characteristics, we consider viscoelectric effects in the analysis. The set of equations is written in dimensionless variables, which are solved with integrodifferential methods, permitting us to obtain semi-analytical solutions for velocity, pressure fields, and the most important: the electric potential generated for the system. This setup converts concentration gradients into electric energy in the form of streaming potential. Besides, we demonstrate that hydrophobic surfaces promote a greater induced streaming potential, nonetheless, for high potentials appears a saturation phenomenon which avoids the growth of the induced electric potential no matter how large the slip-conditions could be.
Acoustic streaming in Maxwell fluids generated by standing waves in two-dimensional microchannels
Journal of Fluid Mechanics
Carlos Vargas 1 , I. Campos Silva2 , Federico Méndez Lavielle3 , José Carlos Arcos Hernández4 , Oscar Eladio Bautista Godínez4
1 Instituto Politécnico Nacional, ESIME Azcapotzalco
2 Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: microfluidics, microscale transport, viscoelasticity
Abstract: In this work, a semianalytic solution for the acoustic streaming phenomenon, generated by standing waves in Maxwell fluids through a two-dimensional microchannel (resonator), is derived. The mathematical model is non-dimensionalized and several dimensionless parameters that characterize the phenomenon arise: the ratio between the oscillation amplitude of the resonator and the half-wavelength ( ?=2A/?a ); the product of the fluid relaxation time times the angular frequency known as the Deborah number ( De=?1? ); the aspect ratio between the microchannel height and the wavelength ( ?=2H0/?a ); and the ratio between half the height of the microchannel and the thickness of the viscous boundary layer ( a=H0/d? ). In the limit when ?«1 , we obtain the hydrodynamic behaviour of the system using a regular perturbation method. In the present work, we show that the acoustic streaming speed is proportional to a2.65De1.9 , and the acoustic pressure varies as a6/5De1/2 . Also, we have found that the growth of inner vortex is due to convective terms in the Maxwell rheological equation. Furthermore, the velocity antinodes show a high dependency on the Deborah number, highlighting the fluid's viscoelastic properties and the appearance of resonance points. Due to the limitations of perturbation methods, we will only analyse narrow microchannels.
Simulation framework for automatic load frequency control studies of VSC-based AC/DC power grids
International Journal of Electrical Power & Energy Systems
Luis Miguel Castro González1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Automatic load frequency control, AC/DC grids, Dynamic modelling, Long-term dynamics, VSC-HVDC links
Abstract: This paper introduces an efficient simulation framework for automatic load frequency control (ALFC) studies of VSC-based AC/DC power grids. It is aimed at slow transients caused by large megawatt imbalances occurring either in the AC systems or DC grid. These studies involve the coordinated action of the primary and secondary control loops of power plants, ones requiring long simulation times ranging from various tens of seconds to minutes. To address these overly challenging AC/DC power system simulations, the developed modelling framework resorts to suitable linear models, i.e., VSC dynamic controls are devised to conform to the slow dynamics featuring the ALFC. The most fundamental dynamics of AC systems, DC grid and VSC stations are compiled with reasonable precision. This is demonstrated using a three-terminal, multilevel VSC-based HVDC system implemented in the PSCAD simulation package for comparative purposes; both solutions are shown to concur very well because root mean squared errors inferior to 3% are obtained. The practicality of this effective simulation framework is also demonstrated by studying a five-terminal VSC-based transmission grid facing large power imbalances imposed by load disconnections and VSC outages.
Producción de múltiples pozos en yacimientos rectangulares naturalmente fracturados con entradas a producción a diferentes tiempos
Revista Internacional de Contaminación Ambiental
Marco Antonio Ávalos Milla1 , Rodolfo Gabriel Camacho Velázquez2
1 Consultor independiente,
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Double-porosity, triple-porosity, NFR, analytical solution
Abstract: En este trabajo se presentan por primera vez dos soluciones analíticas para predecir el perfil de producción de múltiples pozos trabajando a diferentes presiones de fondo constantes, que inician su producción a diferentes tiempos en yacimientos naturalmente fracturados rectangulares con fronteras cerradas al flujo y espesor constante; una para doble porosidad (matriz y fracturas) y la segunda para yacimientos de triple porosidad (matriz, fracturas y cavidades de disolución-vúgulos), ambos con una permeabilidad. Para el caso de doble porosidad, la red de fracturas es la que conduce los fluidos hacia los pozos productores, y en el caso de triple-porosidad, la red de fracturas o la de vúgulos conduce los fluidos hacia el/los pozos. Se presentan, además, sus inversiones analíticas del espacio de Laplace al espacio real, aproximadas para tiempos grandes. Las solu-ciones analíticas fueron invertidas del espacio de Laplace utilizando aproximaciones a tiempos largos, las cuales fueron validadas comparando los resultados con simuladores numéricos. De la misma manera se presentan los resultados de variar los coeficientes de flujo interporoso y las relaciones de almacenamiento de fluidos, observándose comportamientos específicos para cada tipo de yacimiento. Por último, se presenta un contraste en el que se comparan los resultados de un medio poroso homogéneo (1-f), con la variedad de resultados que se pueden obtener si se considera que el yacimiento es de doble porosidad (2-f) o de triple porosidad (3-f). Los modelos propuestos son útiles para predecir el comportamiento de múltiples pozos produciendo de yacimientos naturalmente fracturados con doble porosidad (2-f) y triple porosidad (3-f), así como para realizar análisis económicos de diferentes esquemas de desarrollo de campos cuando la información disponible no justifica el uso de simuladores numéricos
Predictive Control-Based NADIR-Minimizing Algorithm for Solid-State Transformer
Carlos Fuentes 1 , Héctor Chávez 1 , Mario Roberto Arrieta Paternina2
1 Universidad de Santiago de Chile, Departamento de Ingeniería Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Solid-state transformer; predictive control; NADIR; frequency stability
Abstract: Solid-state transformers (SSTs) are becoming an important solution to control active distribution systems. Their significant flexibility in comparison with traditional magnetic transformers is essential to ensure power quality and protection coordination at the distribution level in scenarios of large penetration of distributed energy resources such as renewables, electric vehicles and energy storage. However, the power electronic interface of SSTs decouples the nature of the inertial and frequency responses of distribution loads, deteriorating the frequency stability, especially under the integration of large-scale solar and wind power plants. Despite the virtual inertia/voltage sensitivity-based algorithms that have been proposed, the frequency sensitivity of loads and the capability of guaranteeing optimal control, considering the operating restrictions, have been overlooked. To counteract this specific issue, this work proposes a predictive control-driven approach to provide SSTs with frequency response actions by a strategy that harnesses the voltage and frequency sensibility of distribution loads and considers the limitations of voltage and frequency given by grid codes at distribution grids. In particular, the control strategy is centered in minimizing the NADIR of frequency transients. Numerical results are attained employing an empirically-validated model of the power system frequency dynamics and a dynamic model of distribution loads. Through proportional frequency control, the results of the proposed algorithm are contrasted. It is demonstrated that the NADIR improved about 0.1 Hz for 30% of SST penetration.
Development of the General Bateman Solution using fractional calculus: A theoretical and algorithmic approach
Computer Physics Communications
Carlos Antonio Cruz López1 , Gilberto Espinosa Paredes1 , Juan Luis François Lacouture2
1 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bateman equations, Fractional calculus, General solution, Repeated decay constants, Algorithm
Abstract: In the present work, the General Solution of the Bateman Equation is developed using fractional calculus. Such general solution admits repeated decay constants and it can be used to solve radioactive and transmutation linear chains. Starting from a mass balance equation written in terms of fractional derivatives, it is possible to develop a formula that reproduces the General Bateman Solution when the fractional order is equal to 1. This new procedure allows the solution to be expressed in terms of lambda decay quotients rather than differences and avoids the need for higher-order derivatives or complex evaluations required in other standard methods. An algorithmic methodology to build the developed equation is proposed, which is based in the analysis and reduction of nested sums. Additionally, numerical experiments are included, where a reported case in literature is reproduced accurately as well as a set of cyclic chains that appear in several burnup problems. An analysis of the running time of the developed solution is included, considering a comparison with a similar general equation. This new approach is very advantageous from an algorithmic level, opening the possibility to investigate properties of the Bateman equation from a fractional calculus approach.
Conjugate Heat Transfer in a Thin Microchannel Filled with a Porous Medium
Journal of Thermophysics and Heat Transfer
Ian Guillermo Monsivais Montoliu1 , Federico Méndez Lavielle1 , Ares Gómez 2 , José Joaquín Lizardi Del Ángel3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Glasgow Caledonian University, Department of Mechanical Engineering
3 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: Heat Transfer Coefficients, Thermal Performance, Aspect Ratio, Thermal Conductivity, Uniform Heat Flux, Forced Convection, Fluid Pressure, Micro Heat Exchanger, Kinematic Viscosity, Boundary Layer Thickness
Abstract: We study numerically the conjugate heat transfer between the walls of a parallel plate microchannel and a homogeneous porous medium fully saturated with a liquid that is found in motion due to an external pressure gradient. The origin of this problem is caused by a uniform heat flux imposed at the external surfaces of the walls of the microchannel that have a finite thermal conductivity. In this manner, the competition and heat transfer mechanisms between both regions characterized by the thermal resistances, conduct to a conjugate formulation that originates a dimensionless conjugate parameter ac. This parameter measures the ratio of both thermal resistances, and, for large values of this parameter, the longitudinal heat conduction effects in the walls are very important and suffer significant deviations when compared with the case with finite values for this parameter. The dimensionless governing equations for both regions are established with the corresponding boundary conditions, and the numerical results show that the aspect ratios of both regions, controlled through the dimensionless parameters ?h and ?, play an important role in distinguishing the presence of the longitudinal heat conduction effects in the walls. For instance, if the ratios ac/?2h=25 and ac/?2=1, the longitudinal effects of heat transfer are very important in the walls of the microchannel, whereas in the porous matrix there are effects of heat transfer in both directions, whereas if ac/?2h=ac/?2=25 only the longitudinal conduction effects are significant for both regions.
An Integral Emergency Alert System for Mexico
International Journal of Interdisciplinary Telecommunications and Networking
Elizabet De Armas Sardiñas1 , José María Matías Maruri1 , Víctor García Garduño1 , Andrés Cornejo Gaibor1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: Mexico is a country prone to catastrophic events of seismic, vulcanological or meteorological origin, among others. For this reason, many organizations monitor in Mexico different areas to prevent catastrophes. The Emergency Alert Systems (EAS) advise about the advent of a possible catastrophic event to the population in general. This paper explores the EAS in Mexico in order to propose improvements. First, the characteristics of the existing Emergency Alert Systems in México are evaluated. As the broadcasting have traditionally been the main alert media for the population, the coverage of radio and television is studied in order to know whether it is enough to cover all the country. Finally, a new integral Emergency Alert System covering all the country is proposed.
GIS and geomorphological mapping applied to landslide inventory and susceptibility mapping in the El Estado River basin, Pico de Ori-zaba, Mexico
Journal of Geography and Cartography
José Fernando Aceves Quesada1 , Gabriel Legorreta Paulín1 , José Lugo Hubp1 , Juan Umaña Romero2 , Héctor Alfredo Legorreta Cuevas2
1 Universidad Nacional Autónoma de México, Instituto de Geografía
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: GIS; Geomorphological Mapping; Landslide Inventory Map; Landslide Susceptibility Map; Multiple Logistic Re-gression; Pico de Orizaba Volcano
Abstract: With the purpose of strengthening the knowledge and prevention of landslide disasters, this work develops a methodology that integrates geomorphological mapping with the elaboration of landslide susceptibility maps using geographic information systems (GIS) and the multiple logistic regression method (MLR). In Mexico, some isolated works have been carried out with GIS to evaluate slope stability. However, to date, no practical and standardized method has been developed to integrate geomorphological maps with landslide inventories using GIS. This paper shows the analysis carried out to develop a multitemporal landslide inventory together with the morphometric analysis and mapping technique for the El Estado River basin where, selected as the study area, is located on the southwestern slope of the Citlaltepetl or Pico de Orizaba volcano. The geological and geomorphological factors in combination with the high seasonal precipitation, the high degree of weathering and the steep slopes predispose its surfaces to landslides. To assess landslide susceptibility, a landslide inventory map was prepared using aerial photographs, followed by geomorphometric mapping (altimetry, slopes and geomorphology) and field work. With this information, landslide susceptibility was modeled using multiple logistic regression (MLR) within a GIS platform and the landslide susceptibility map was obtained.
Repetitive corrugation and straightening effect on the microstructure, crystallographic texture and electrochemical behavior for the Al-7075 alloy
Journal of Applied Research and Technology
Liliana Romero Resendiz1 , Miguel Ángel Hernández Gallegos2 , José María Cabrera 3 , Sergio Elizalde 4 , Vicente Amigó Borrás5 , Ignacio Alejandro Figueroa 1 , Alba Covelo Villar2 , Gonzalo González 1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Politécnica de Cataluña, Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica
4 Universitat Politècnica de Catalunya, Departamento de Ciencia e Ingeniería de Materiales
5 Universitat Politècnica de València, Instituto de Tecnología de Materiales

Keywords: Aluminum alloy, Texture, Electrochemical impedance spectroscopy, Microstructure, Corrosion, X-ray diffraction
Abstract: Anti-corrosion susceptibility is one of the top criteria for selecting metallic materials for several industrial applications. This work studies the corrosion performance on an Al-7075 alloy obtained by Repetitive Corrugation and Straightening (RCS). This processing method generated a microstructure formed by randomly distributed micro-, submicro-, and nano- metric grain sizes. The samples exhibited a drop in corrosion resistance for a longer duration in the electrolyte and higher deformation. However, the samples processed by RCS showed better electrochemical stability in comparison with the non-deformed condition. The improvement of electrochemical stability could be associated with the particular microstructure generated during the RCS process.
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