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Artículos publicados en: 2016

A generalized frame of reference for the incorporation of, multi-terminal VSC-HVDC systems in power flow solutions
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2016.03.009
Enrique Ancha 1 , Luis Miguel Castro González 2
1 Tampere University of Technology, Department of Electrical Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: MT-HVDC systems, Newton-Raphson method, Power flows, VSC-HVDC modeling
Abstract: This paper introduces a new and general frame-of-reference for true unified, iterative solutions of AC/DC power flows using the Newton-Raphson method. The emphasis is placed on the so-called multi-terminal VSC-HVDC systems. This frame-of-reference accommodates quite naturally any number of AC/DC sub-networks generated by an arbitrary number of VSC converters. Besides, each AC sub-network may contain any number of FACTS devices. The modeling approach adopted for the multi-terminal VSC-HVDC systems is incremental in nature. An AC system of arbitrary configuration is connected to the high-voltage side of the VSC's LTC transformer. In turn, the DC side of each pairing VSC is linked to a DC system of arbitrary configuration. The new model represents a paradigm shift in the way the fundamental frequency, positive sequence modeling of VSC-HVDC links are modeled, where the VSCs are not treated as idealized, controllable voltage sources but rather as compound transformer devices with which key control properties of the PWM-based converters are linked. In contrast to other contemporary approaches, the power flow iterative solutions carried out using the reference frame put forward in this paper exhibits a true quadratic convergence characteristic ?? in most credible cases, convergence to a tight power mismatch tolerance of e??12 would be achieved in five or less iterations.
Output feedback sliding-mode control with unmatched disturbances, an ISS approach
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.3548
Andrea Aparicio 1 , Fernando Castaños 2 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Cinvestav

Keywords: sliding?mode control, input?to?state stability, output feedback, matched and unmatched disturbances
Abstract: The robustness properties of a first?order sliding?mode controller are combined with those of an added linear term in order to obtain a closed loop that shows input?to?state stability with respect to matched and unmatched disturbances, of which an upper bound might not be known, using only output information. The output under consideration can have any relative degree. Also, a transformation of the state into a novel output normal form is presented. The zero dynamics are considered unstable and perturbed, so a methodology for defining an observer and a virtual control for it is presented.
3D-ERT geophysical prospecting for the investigation of two terraces of an archaeological site northeast of Tlaxcala state, Mexico
Journal of Archaeological Science: Reports
https://doi.org/10.1016/j.jasrep.2016.06.047
Denisse L. Argote Espino 1 , Pedro A. López García 2 , Andrés Tejero Andrade 3
1 Instituto Nacional de Antropología e Historia, Dirección de Estudios Arqueológicos
2 Escuela Nacional de Antropología e Historia, Posgrado de Arqueología
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: 3D-ERT, Archaeological prospecting, Electrical anomalies, Teteles de Ocotitla, Tlaxcala, Mexico
Abstract: Teteles de Ocotitla is an archaeological site located in the central portion of the Sierra of Ocotitla, northeast of the State of Tlaxcala. This site is mostly composed of several artificial terraces with evidence of human occupation, probably contemporary with Teotihuacan in the Early Classic period. The aim of this research was to determine the existence and spatial distribution of non-visible archaeological structures on two of the upper terraces of the site, as well as to determine potential areas to carry out archaeological excavations. For this reason, the geophysical method of Electrical Resistivity Tomography in 3D was implemented, identifying four anomalous areas of interest as well as their respective depths. This non-destructive geophysical method is considered a rapid, self-sufficient, useful and non-invasive procedure to detect archaeological structures; therefore, it was essential to this research. The archaeological excavations confirmed the existence of platforms, walls and other pre-Hispanic elements, which proved the efficiency of the geophysical method in the characterization of buried pre-Hispanic architectural structures.
Shallow geoelectrical characterization of a small portion of the Basin of Mexico aquifer: Towards a better resource management
Geofísica Internacional
http://dx.doi.org/10.22201/igeof.00167169p.2016.55.3.1723
Claudia Arango Galván 1 , Elsa Leticia Flores Márquez 1 , Antonio Hernández Espriú 2 , Alberto Arias Paz 2 , Edgar Jesús Sagahón López 3
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Benemérita Universidad Autónoma de Puebla, Facultad de Ingeniería

Keywords: Basin of Mexico, overexploitation, time domain electromagnetic, water resource management, water security
Abstract: Shortage in supply of fresh water in megacities is becoming increasingly common. Mexico City is part of this problem because dramatic reductions in groundwater levels have been observed in recent years along with associated problems such as subsidence and poor water quality, endangering access to this resource. The Ciudad Universitaria campus is located in the southern part of this mega city and has over 150,000 users, whose clean water demand is met from three abstraction wells supplying almost three million cubic meters per year. However, the configuration of this portion of the Mexico Basin aquifer is not well known and has shown a strong depletion in the water table. Thus, an integrated study was conducted with the aim to characterize this portion of the aquifer to provide information that allows carrying out a better assessment of its current situation and improving its management. Despite the difficulty to conduct a direct characterization of the hydrogeological units outcropping in the area since almost all the campus is covered with infrastructure (i.e. academic facilities, roads, gardens), a geological reconnaissance was carried out in the vicinity of exploitation wells and a geophysical characterization was performed using time-domain electromagnetics. Additio-nally, a pumping test was conducted in the main exploitation well in order to estimate hydraulic properties of the aquifer. Thus, the integration of these techniques allows inferring some important issues regarding the aquifer and its exploitation in this area.
Dynamic Characterization of Typical Electrical Circuits via Structural Properties
Mathematical Problems in Engineering
https://doi.org/10.1155/2016/7870462
Sofía Ávila Becerril 1 , Gerardo Espinosa Pérez 1 , Paul Fernandez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: The characterization of a class of electrical circuits is carried out in terms of both stability properties and steady-state behavior. The main contribution is the interpretation of the electrical topology (how the elements that conform the circuits are interconnected) in terms of mathematical properties derived from the structure of their models. In this sense, at what extent the topology by itself defines the dynamic behavior of the systems is explained. The study is based on the graph theory allowing capturing, departing from the well-known Kirchhoff laws, the topology of the circuits into several matrices with specific structure. The algebraic analysis of these matrices permits identifying conditions that determine whether the system is stable in the sense of Lyapunov and the kind of steady-state behavior that it exhibits. The approach is mainly focused on typical topologies widely used in practice, namely, radial, ring, and mesh networks.
Alternatives for vacuum generation in unconventional seawater desalination systems
Desalination and Water Treatment
https://doi.org/10.1080/19443994.2016.1167626
Héctor Miguel Aviña Jiménez 1 , Gabriel León De los Santos 2 , Daniel Sauceda Carbajal 3 , Fernando García Torres 1 , Miguel Ángel Benítez Torreblanca 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Centro de Investigación Científica y de Educación Superior de Ensenada, División de Física Aplicada

Keywords: Vacuum generation, Seawater desalination, Multiple-effect distillation, Low-enthalpy geothermal energy, Brackish water desalination
Abstract: Seawater desalination is a viable option to reduce water shortage problems. As a consequence, the development of technologies that can guarantee the availability of water resources is essential. This article primarily focuses on the study and theoretical analysis of a vacuum generation system for a modular desalination unit with low-enthalpy geothermal energy as power source. This desalination unit, currently in the Research & Development stage, aims to be an effective, low-cost and marketable product, fulfilling the need of water in regions that have both, the energy source, and the lack of drinking water, such as northwestern Mexico. Based on the dissertation presented, the use of a hydroejector is proposed, discussing the feasibility of the use of steam or air as working fluid.
Segmentation and optical flow estimation in cardiac CT sequences based on a spatiotemporal PDM with a correction scheme and the Hermite transform
Computers in Biology and Medicine
https://doi.org/10.1016/j.compbiomed.2015.12.021
Leiner Barba Jiménez 1 , Ernesto Moya Albor 2 , Boris Escalante Ramírez 1 , Jorge Brieva 2 , Enrique Vallejo Venegas 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Panamericana, Facultad de Ingeniería
3 Centro Médico ABC, Cardiología

Keywords: Segmentation, Spatiotemporal point distribution model, Local image features, Optical flow, Hermite transform, Cardiac CT sequences
Abstract: Purpose: The left ventricle and the myocardium are two of the most important parts of the heart used for cardiac evaluation. In this work a novel framework that combines two methods to isolate and display functional characteristics of the heart using sequences of cardiac computed tomography (CT) is proposed. A shape extraction method, which includes a new segmentation correction scheme, is performed jointly with a motion estimation approach. Methods: For the segmentation task we built a Spatiotemporal Point Distribution Model (STPDM) that encodes spatial and temporal variability of the heart structures. Intensity and gradient information guide the STPDM. We present a novel method to correct segmentation errors obtained with the STPDM. It consists of a deformable scheme that combines three types of image features: local histograms, gradients and binary patterns. A bio-inspired image representation model based on the Hermite transform is used for motion estimation. The segmentation allows isolating the structure of interest while the motion estimation can be used to characterize the movement of the complete heart muscle. Results: The work is evaluated with several sequences of cardiac CT. The left ventricle was used for evaluation. Several metrics were used to validate the proposed framework. The efficiency of our method is also demonstrated by comparing with other techniques. Conclusion: The implemented tool can enable physicians to better identify mechanical problems. The new correction scheme substantially improves the segmentation performance. Reported results demonstrate that this work is a promising technique for heart mechanical assessment.
Geochemistry of pelagic sediments and nodules in the abyssal clarion fracture zone, Western Mexico
Carpathian Journal of Earth and Environmental Sciences
http://www.ubm.ro/sites/CJEES/viewTopic.php?topicId=631
Mayumi Amparo Cabrera Ramírez 1 , Arturo Carranza Edwards 2 , John Armstrong Altrin 2 , Leticia Rosales Hoz 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología

Keywords:
Abstract: An oceanographic cruise on board the R/V El Puma (from the National Autonomous University of Mexico) was performed around the volcanic rocks of Clarion Island (CIR) in the western region of the Exclusive Economic Zone (EEZ) of Mexico. Surface sediments, nodules and representative rock samples from the CIR were collected. Texture is mainly constituted by silt and clay that suggest the influence of pelagic muds carried from the mainland to the deep sea by sea currents. The sandy fraction (less abundant) of the sediments is characterized by micronodules, pumice and remains of siliceous organisms. The most abundant muddy sediment fraction contains smectite, which played a role in the incorporation and release of metals and REE into the polymetallic nodules. The Mn, Ni, Co and REE concentrations in the studied sediments and nodules were slightly enriched when compared to UCC, NASC and CIR rocks.
Interferometría de ruido sísmico para la caracterización de la estructura de velocidad 3D de un talud en la 3a Sección del Bosque de Chapultepec, Ciudad de México
Boletín de la Sociedad Geológica Mexicana
http://dx.doi.org/10.18268/BSGM2016v68n2a1
Martín Cárdenas Soto 1 , Horacio Ramos Saldaña 1 , Martín Carlos Vidal García 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Deslizamientos de masa, estabilidad de talud, refracción sísmica, ondas superficiales, correlación de ruido
Abstract: En este trabajo aplicamos el método de Interferometría Sísmica (IS) para determinar la variación lateral en la distribución de la velocidad de onda S (Vs) en la estructura de un macizo rocoso que contiene un talud localizado en el circuito Joaquín Claussell de la 3a Sección del Bosque de Chapultepec. Estudios geológicos y de geotecnia muestran la presencia de un estrato pumicítico, que sobreyace a materiales semi permeables; el cual es susceptible a fallamiento y provocar deslizamientos, debido al estado de fracturamiento y el aporte de agua durante la época de lluvias, factores comúnmente asociados a deslizamientos en la zona poniente de la Ciudad México. A fin de mostrar la aplicabilidad del método de IS para cuantificar las propiedades elásticas y su distribución en los estratos que conforman el cuerpo del talud, se generaron funciones de correlación cruzada entre 4560 pares de receptores en un arreglo irregular de 96 geófonos verticales. Mediante el uso de las variaciones temporales del máximo pulso de correlación en función de la frecuencia (4 a 24 Hz), construimos imágenes a partir de la tomografía de Vs relativa. Encontramos que valores de Vs cercanos a 300 m/s se relacionan con los estratos de pómez, los cuales se encuentran principalmente alojados hacia la cara del talud y en su parte topográfica más baja. La velocidad en estos materiales contrasta notablemente con la del estrato subyacente de valores superiores a 1000 m/s. Los valores de Vs y la geometría del estrato susceptible a deslizarse fueron corroborados por dos líneas de refracción sísmica. Los resultados de este estudio, sugieren que el método de IS es apropiado, debido a su carácter no invasivo ni destructivo, para analizar este tipo de riesgos geológicos asociados con la estabilidad de taludes.
A Unified Modeling Approach of Multi-Terminal VSC-HVDC Links for Dynamic Simulations of Large-Scale Power Systems
IEEE Transactions on Power Systems
https://doi.org/10.1109/TPWRS.2016.2527498
Luis Miguel Castro González 1 , Enrique Acha Daza 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Tampere University of Technology, Department of Electrical Engineering

Keywords: Multi-terminal VSC-HVDC systems, Newton-Raphson method, VSC-HVDC dynamic modeling
Abstract: This paper introduces a new and general frame-of-reference for dynamic solutions of multi-terminal VSC-HVDC systems using the Newton-Raphson method. Three VSC dynamic models are derived to conform to each pairing AC sub-network-the slack converter whose aim is to control its DC voltage, the scheduled-power converter which injects a scheduled amount of power and the passive converter which is connected to an AC network with no frequency control equipment. Each VSC unit makes provisions for the phase reactor, AC filter, DC capacitor, DC smoothing inductor and LTC transformer. The VSC itself is a positive-sequence lumped-type model whose core elements are a phase-shifting transformer and an equivalent shunt susceptance which account for the phase-shifting and scaling nature of the PWM control. In turn, the DC side of each pairing VSC unit is linked to a DC system of an arbitrary configuration. All this enables the assembly of any number of VSCs, giving rise to a comprehensive formulation of multi-terminal VSC-HVDC systems. The prowess of the proposed multi-terminal dynamic model is demonstrated by carrying out a comparison against the widely-used EMT-type package Simulink, using a three terminal VSC-HVDC system, with very good results. Furthermore, a six-terminal VSC-HVDC system forming a DC ring is used to show the applicability of the proposed unified approach when solving multi-terminal VSC-HVDC links for system-wide dynamic studies.
Implementation of Super-Twisting Control: Super-Twisting and Higher Order Sliding-Mode Observer-Based Approaches
IEEE Transactions on Industrial Electronics
https://doi.org/10.1109/TIE.2016.2523913
Asif Chalanga 1 , Shyam Kamal 1 , Leonid Fridman Golredich 2 , Bijnan Bandyopadhyay 1 , Jaime Alberto Moreno Pérez 3
1 Indian Institute of Technology, Systems and Control Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Observers, Output feedback, Closed loop systems, Convergence, Uncertainty, Robustness
Abstract: In this paper, an output feedback stabilization of perturbed double-integrator systems using super-twisting control (STC) is studied. It is shown that when STC is implemented based on super-twisting observer (STO), then it is not possible to achieve second-order sliding mode (SOSM) using continuous control on the chosen sliding surface. Two methodologies are proposed to circumvent the above-mentioned problem. In the first method, control input is discontinuous, which may not be desirable for practical systems. In the second method, continuous STC is proposed based on higher order sliding mode observer (HOSMO) that achieves SOSM on the chosen sliding surface. For simplicity, we are considering here only the perturbed double integrator, which can be generalized for an arbitrary-order systems. Numerical simulations and experimental validation are also presented to show the effectiveness of the proposed method.
Prediction of temperature profiles and ampacity for a monometallic conductor considering the skin effect and temperature-dependent resistivity
Applied Thermal Engineering
https://doi.org/10.1016/j.applthermaleng.2016.08.044
Oscar Chávez 1 , Francisco Antonio Godínez Rojano 2 , Federico Méndez Lavielle 3 , Alicia Aguilar Corona 4
1 Instituto Tecnológico de Chihuahua, División de Estudios de Posgrado e Investigación
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Mecánica

Keywords: Ampacity, Skin effect, Thermal behavior, Temperature-dependent resistivity
Abstract: In the present work, we have developed a theoretical model to examine the combined effects of heat conduction produced by Joule??s effect and an alternating current signal that flows in a circular electric conductor, taking into account variations of electric resistivity with temperature. The above hypothesis leads to a coupled thermo-electric formulation. Under this approach and considering an electric current composed by high frequencies, we have considered the presence of the skin effect that yields important radial differences of temperature controlled by the heat conduction equation for the conductor. On the other hand, a wave equation is required to analyze the electromagnetic propagation of the current. It is well-known that high-voltage transmission lines are constructed with conductive materials that are composed by strands, for this reason, trapped-air between these strands complicates the analysis of the electromagnetic conduction phenomena. To circumvent this problem, the air-aluminum system is represented by a porous medium with effective properties used in the mathematical model for the heat conduction equation. Finally, the imposed thermal boundary conditions reveal that the environmental conditions are a fundamental factor to control the above effects.
Simulation Model and Comparison for Satellite Links in Ku and Ka Bands for Standards-based on DVB-S2 and NS3
IEEE Latin America Transactions
https://doi.org/10.1109/TLA.2016.7483502
Andrés Cornejo 1 , Salvador Landeros Ayala 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Satellite, Satellite broadcasting, Satellite Communication, Satellite earth station
Abstract: This work generates a simulation model to understand the effects of attenuation in broadcasting satellite links like for data links and especially to determine the feasibility of using a high performance satellite backhaul for new generation data networks, faced with different scenarios especially in areas where rainfall attenuates and degrades the RF satellite links. Predictive models have been assembled delivered by the ITU and its recommendations for rain attenuation and the links are integrated with DVB-S2 and NS3 standards, where the simulated model will be obtained which with a position geographical coordinates as a reference of the remote station VSAT, will result in operating modes, signal strength and availability of the satellite link given. This certainly makes it a tool to study and design that many papers omitted on the research part and it becomes necessary to be applied in new models of propagation and attenuation in regions where it is desired to conduct the study, achieving thus a greater precision in the quality of links and a more encouraging panorama to deploy networking data systems high reliability and high transmission rates based on next generation 4G and future 5G networks.
Long Duration of Ground Motion in the Paradigmatic Valley of Mexico
Scientific Reports
https://doi.org/10.1038/srep38807
Víctor M. Cruz Atienza 1 , Josué Tago Pacheco 2 , J. D. Sanabria Gómez 3 , E. Chaljub 4 , V. Etienne 5 , Jean Virieux 6 , L. Quintanar 1
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Industrial de Santander, Escuela Física
4 Univiversité de Grenoble Alpes, ISTerre
5 ARAMCO, Advanced Research Center
6 Universite Grenoble Alpes, Institut des Sciences de la Terre

Keywords: Applied mathematics, Geophysics, Natural hazards, Seismology
Abstract: Built-up on top of ancient lake deposits, Mexico City experiences some of the largest seismic site effects worldwide. Besides the extreme amplification of seismic waves, duration of intense ground motion from large subduction earthquakes exceeds three minutes in the lake-bed zone of the basin, where hundreds of buildings collapsed or were seriously damaged during the magnitude 8.0 Michoacán earthquake in 1985. Different mechanisms contribute to the long lasting motions, such as the regional dispersion and multiple-scattering of the incoming wavefield from the coast, more than 300??km away the city. By means of high performance computational modeling we show that, despite the highly dissipative basin deposits, seismic energy can propagate long distances in the deep structure of the valley, promoting also a large elongation of motion. Our simulations reveal that the seismic response of the basin is dominated by surface-waves overtones, and that this mechanism increases the duration of ground motion by more than 170% and 290% of the incoming wavefield duration at 0.5 and 0.3??Hz, respectively, which are two frequencies with the largest observed amplification. This conclusion contradicts what has been previously stated from observational and modeling investigations, where the basin itself has been discarded as a preponderant factor promoting long and devastating shaking in Mexico City.
Delayed sliding mode control
Automatica
https://doi.org/10.1016/j.automatica.2015.10.055
Denis Efimov 1 , Andrey Polyakov 2 , Leonid Fridman Golredich 3 , Wilfrid Perruquetti 1 , Jean Pierre Richard 4
1 Villenueve d'Ascq, Nord Europe Center
2 ITMO University, Department of Control Systems and Informatics
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Ecole Centrale de Lille, CRIStAL

Keywords: Sliding mode, Time delay, Stability analysis
Abstract: A new sliding mode control approach is introduced in this work with the dedicated mathematical tools. A time-delay modification/approximation of sign function is proposed, and it is shown that by substituting this new "sign? realization in the conventional sliding mode algorithms the main advantages of the sliding mode tools are preserved (like rejection of matched disturbances and hyper-exponential convergence, i.e. the rate of convergence to the origin is much faster than any exponential (Polyakov, Efimov, Perruquetti, & Richard, 2014)), while the chattering is reduced. These results are illustrated and confirmed by numerical simulations for the first order sliding mode control and the super-twisting algorithm.
Aplicación de funciones de distribución continuas para modelar la demanda de pasajeros en una línea de tren ligero
Contaduría y Administración
https://doi.org/10.1016/j.cya.2015.09.002
Alexei Gómez Eguiarte-Martínez 1 , Gabriel De las Nieves Sánchez-Guerrero 2
1 Sistema de Transporte Colectivo - Metro
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Demanda de pasajeros, Variable aleatoria, Función de distribución continua, Sistema de transporte colectivo
Abstract: El sistema de tren ligero referido en el presente trabajo es un sistema eficiente y popular de transporte público que sirve en extensas áreas de la zona metropolitana del Valle de México. Encuestas a los pasajeros muestran que la demora en los trenes es el reto más importante a satisfacer. La demanda de pasajeros es el dato más relevante para la programación del servicio. Ha habido pocos intentos por abordar esta problemática: la carencia de información confiable ha sido una fuerte limitante. El propósito de esta investigación fue modelar la demanda diaria de pasajeros utilizando los datos obtenidos por los dispositivos de entrada (torniquetes) a las estaciones, prescindiendo de técnicas tradicionales para describir la afluencia de pasajeros. De manera que la investigación se orientó a obtener funciones de distribución continuas que se ajustaran a la demanda de pasajeros en una línea particular y sus estaciones. Se obtuvieron y analizaron datos correspondientes al flujo del año 2010 y se introdujeron en una base de datos compatible con software estadístico. Los modelos propuestos fueron obtenidos por estimación de máxima verosimilitud y corresponden a funciones de distribución de probabilidad continuas, con soporte en los reales positivos.
Análisis de frecuencias no estacionario de series de lluvia anual
Tecnología y Ciencias del Agua
http://revistatyca.org.mx/ojs/index.php/tyca/articleCms/view/1151/1055
Gabriela Álvarez Olguín 1 , Carlos Agustín Escalante Sandoval 2
1 Universidad Tecnológica de la Mixteca, Instituto de Hidrología
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: análisis de frecuencias, series no estacionarias, escasez de agua, sequías, disponibilidad de agua, cambio climático, noroeste de México
Abstract: En las zonas del noroeste de México, donde existe una alta presión sobre el agua, las estrategias para afrontar periodos de escasez de este recurso podrían fallar si la disponibilidad se evalúa a través de valores medios de escurrimientos o precipitación, sin considerar el cambio en el comportamiento de tales variables. El objetivo de este trabajo fue estimar eventos de lluvia acumulada anual del noroeste de la república mexicana, asociados con diferentes periodos de retorno y escenarios futuros. Para siete funciones de probabilidad de valores mínimos se propusieron tres modelos no estacionarios válidos para series cuyas características estadísticas se han modificado a través del tiempo. Se analizaron 221 series de lluvia acumulada anual, de las cuales se determinó que 36 (16%) no son estacionarias; para 30 de éstas, los modelos no estacionarios representan mejor la variabilidad de los datos que los modelos convencionales. Se predice para el año 2044 una disminución menor que 20% de la lluvia media anual, en estaciones ubicadas en la península de California, Sonora y Sinaloa. Los resultados sugieren que estas zonas serán más susceptibles a sequías en el futuro.
Flood frequency analysis using synthetic samples
Atmósfera
https://doi.org/10.20937/ATM.2016.29.04.02
Luis Orsini Zegeda 1 , Carlos Agustín Escalante Sandoval 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Flood frequency analysis, small samples, synthetic samples, uncertainty
Abstract: El flujo de diseño es la base para la planeación y el diseño de obras hidráulicas. La precisión en el cálculo de flujos es importante para el análisis de viabilidad de dichas estructuras porque el valor estimado influye directamente en la evaluación de los efectos de falla. Sin embargo, en razón de la variabilidad, la precisión del cálculo se reduce de manera drástica cuando se utilizan muestras pequeñas en el análisis de frecuencia de inundaciones (FFA, por sus siglas en inglés) convencional. En este trabajo se plantea un nuevo enfoque basado en la simulación combinada de flujos anuales máximos y medios. El método se evaluó tomando en consideración submuestras de 10, 20, 30, 40 y 50 años obtenidas a partir de 13 estaciones pluviométricas ubicadas en la cuenca del río Susquehanna. Los resultados se compararon con los obtenidos mediante FFA y el análisis regional de estaciones-año. Este enfoque novedoso puede reducir la incertidumbre en las estimaciones del flujo de diseño cuando los datos asequibles son escasos.
Passivity?based power control of a doubly fed induction generator with unknown parameters
International Transactions on Electrical Energy Systems
https://doi.org/10.1002/etep.2213
Irvin López García 1 , Francisco Beltran Carbajal 1 , Gerardo Espinosa Pérez 2 , Rafael Escarela Pérez 1
1 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: passivity?based control, doubly fed induction generator, parameter identification
Abstract: An alternative solution for power regulation of doubly fed induction generators is proposed in this work by a proper combination of passivity?based controllers with algebraic approaches for online estimation of system parameters and mechanical torque. Our proposal shows that the stability property of the original closed?loop system is preserved, without the restriction of explicitly knowing the parameters and mechanical torque of the induction generator. A performance evaluation study is performed on the passivity?based power control scheme considering typical/normal operation conditions for the electrical power generation system, namely active power generation with either demanded or delivered reactive power. Analytical and numerical results prove the effectiveness of the power control scheme combined with the proposed real?time estimators of parameters and torque.
Closely spaced tri-band frequency selective surfaces based on split ring slots
Electronic Letters
https://doi.org/10.1049/el.2016.0255
Henry Fabian Gongora 1 , Alexander Martynyuk 1 , Jorge Rodríguez Cuevas 1 , José Ismael Martínez López 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: frequency selective surfaces, microwave antenna arrays, multifrequency antennas
Abstract: A tri-band frequency selective surface (FSS) with close band spacing based on split ring slots for y -polarised incident waves is investigated. The close band response is obtained by reducing the strong mutual coupling between the closely packed concentric rings through splitting the ring slots and redistributing the location of the surface currents at resonances. To validate the proposed FSS, a Ka band FSS was designed, fabricated and tested. Experimental results showed closely spaced resonances at 27.3, 31.7 and 36.2 GHz. Frequency ratios of 1.16 for the second to the first resonance, and 1.14 for the third to the second one were obtained. Also, good stability is observed for oblique incidence.
Tribological and Microstructural Characterization of Ultrafine Layers Induced by Wear in Ductile Alloys
Tribology Online
https://doi.org/10.2474/trol.11.389
Carlos Gabriel Figueroa 1 , Rafael Schouwenaars Franssens 2 , Víctor Hugo Jacobo Armendáriz 2 , Armando Ortiz Prado 2 , Roumen Petrov 3 , Leo Kestens 3
1 Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Aragón
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Ghent University, EEMMeCS Department

Keywords: tribology, tribolayers, nanocrystalline Al-Sn, Cu, AFM, EBSD
Abstract: This work studies the ultrafine subsurface layer produced in Al-Sn and Cu alloys in contact with AISI9840 steel. The tribological tests were conducted at room temperature without lubrication in a coaxial tribometer. A first microstructural characterization was performed using conventional scanning electron microscopy (SEM) and atomic force microscopy (AFM). Grain refinement mapping was performed by means of Electron Backscattering Diffraction (EBSD). The wear process, during which tribolayers are formed, leads to significant differences between the structure of the sub-micrometrical layer below the tribolayer and that of the bulk. SEM images show severe mechanical mixing in the surface of the worn zones, whereas EBSD observations allow identifying the mechanically homogenized layers as a sub-micro-crystalline material with a cellular structure aligned along the sliding direction.
Primed Low Frequency Transcranial Magnetic Stimulation Effects on Smoking Cue-Induced Craving
Revista Mexicana de Ingeniería Biomédica
https://doi.org/10.17488/RMIB.37.1.3
Miguel Flores Leal 1 , Emilio Sacristán 2 , Luis Jiménez Ángeles 3 , J. Azpiroz Lechan 1
1 Universidad Autónoma Metropolitana, Iztapalapa
2 Universidad Autónoma Metropolitana, Departamento de Ingeniería Eléctrica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: rTMS, fMRI, nicotine craving, priming
Abstract: Repetitive Transcranial Magnetic Stimulation (rTMS) has shown the potential to reduce craving to smoke and the amount of cigarettes smoked. When low frequency rTMS is preceded by a priming session the cortical inhibitory effects are enhanced provoking a lasting performance. In this study we evaluate the brain regional activations and self-reported mood effect of one session of primed low frequency rTMS over the left dorsolateral prefrontal cortex (DLPFC) in response to smoking-related cues during temporary nicotine abstinence. Ten moderate nicotine-dependent subjects participated in a crossover design, comparing a single session of active versus sham stimulation. After treatment, a functional Magnetic Resonance Imaging (fMRI) study was performed on all participants while completing a block-design cue reactivity paradigm. Our measures also included self-reported craving and mood score before and after every rTMS session. The number of daily smoked cigarette in a one week around period was also recorded. The results show that self-reported cravings were lower following the active stimulation; significant activation was found in areas associated with emotion control (anterior cingulate gyrus and subgenual area) and episodic memory (precuneus and posterior cingulate gyrus) as a result of the stimulation. No significant difference was found in the number of cigarettes smoked and mood scores between the sham and active condition during the one week period records. This study confirms the previous evidence that rTMS can reduce cigarette cravings and provides evidence of the neural mechanism of action that take place in order to achieve these neuromodulation effects.
A comparison between oxide and metallic fueled ASTRID-like reactors
Annals of Nuclear Energy
https://doi.org/10.1016/j.anucene.2016.04.004
Elías Yammir García Cervantes 1 , Juan Luis François Lacouture 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: ASTRID, Sodium-cooled fast reactor, Oxide fuel, Metallic fuel
Abstract: In order to limit the greenhouse emissions and ensure energy security, the global climate change perspective implies a modification in the future energy sector supply. Nuclear energy is an alternative that would decrease the amount of greenhouse gas emissions, and specifically, the fourth generation reactors that present a favorable outlook for clean energy supply. In particular, the Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID) is a fourth generation sodium-cooled pool type fast nuclear reactor of 1500 MWth that seems to be a promising design into the commercial fast nuclear reactors. One of the different core designs for ASTRID is a low void effect core (CFV: C?ur à Faible effet de Vidange sodium) due to the reactor configuration and the radial and axial position of the fuel subassemblies. The current paper presents a heterogeneous ASTRID model developed in MCNP6 with JEFF-3.2 cross sections library, in which three neutronic parameters (Keff at End of Cycle, Doppler constants and coolant void worth) are validated with the European Benchmark on the ASTRID-like low-void-effect core characterization, presented in the ICAPP conference in Nice, France, on May 2015. Validation of the ASTRID model was successfully accomplished, having slightly differences with the benchmark participants in the neutronic parameters. Once the validation was done, a metallic fueled ASTRID-like design is proposed and compared with the oxide fueled reactor. Criticality analysis was done in order to understand the reactor behavior during one cycle of operation as well as Doppler constants and coolant void worth comparison. Actinide inventory was analyzed for both models and 239Pu was tracked with the purpose of observing the breeding achieved in the fertile blankets. Reactivity at the End of Cycle had only a 3 pcm delta Keff difference in comparison with the oxide design, Doppler constants behaved as expected and coolant void worth for the whole core has a negative reactivity effect, which is the essential characteristic of the CFV core. Metallic model performed 8.57% more breeding in isotope 239Pu than the conventional oxide fueled design in the fertile zone, and in the global actinide inventory achieved 3% more 239Pu. Metallic design enhances the plutonium management because, besides that the reactor can be sustained in a supercritical state with less initial Pu enrichment, breeding has a better performance.
Estimation of the fast neutron fluence in Laguna Verde RPV-Steel specimens simulating their irradiation in a TRIGA reactor
Progress in Nuclear Energy
https://doi.org/10.1016/j.pnucene.2015.12.014
Juan Galicia Aragón 1 , Juan Luis François Lacouture 1 , Fortunato Aguilar Hernández 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Nacional de Investigaciones Nucleares

Keywords: TRIGA, Monte Carlo, Neutron activation, Neutron fluence
Abstract: The main purpose of this paper is to predict the fast neutron fluence value expected at four Laguna Verde Nuclear Power Plant RPV-steel specimens, when they are loaded in Mexican TRIGA Mark III reactor. Numerical simulation is done by neutronic calculation with MCNP5 Monte Carlo code for a detailed model of this research reactor core. This calculation will enable the estimation of the irradiation time needed for aging the specimens quickly. In the first part of this work, the MCNP5 developed model was validated through different operating conditions of the TRIGA reactor. The core was simulated to analyze the behavior of the keff when all the control rods are fully withdrawn and fully inserted in cold conditions (293 K); an analysis of the behavior of keff when only the regulating control rod is fully withdrawn is also included. Real operating conditions of the reactor at a power of 1 MWth in steady state were also simulated, in order to obtain the neutron flux in the six irradiation holes of the TRIGA reactor. The calculation of the axial neutron flux in each irradiation hole was validated applying the Neutron Activation Analysis technique (NAA), to calculate the activity of different materials that were irradiated in the TRIGA reactor; the results were compared with the activity calculated with MCNP5 for each material. Afterwards, the fast neutron flux that the RPV-steel specimens received in the experimental facility E??16 was also calculated with MCNP5. Finally, the irradiation time of the specimens in the TRIGA was estimated in order to obtain values of the fast neutron fluence at 24, 32 and 48 Effective Full Power Years (EFPY).
Continuous output integral sliding mode control for switched linear systems
Nonlinear Analysis: Hybrid Systems
https://doi.org/10.1016/j.nahs.2016.05.007
Rosalba Galván Guerra 1 , Leonid Fridman Golredich 2 , Juan Eduardo Velázquez Velázquez 1 , Shyam Kamal 3 , Bijnan Bandyopadhyay 3
1 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Indian Institute of Technology, Systems and Control Engineering

Keywords: Continuous output integral sliding mode, Switched system, Chattering attenuation
Abstract: A continuous output integral sliding mode robustification methodology for switched uncertain linear time invariant systems with state-dependent location transitions and dwell time is presented. The robustifying methodology is based on the adjustment of the super-twisting algorithm gains to assure the convergence time and the attenuation of the chattering. The use of the adjusted STA allows to reconstruct the states theoretically exactly before half of the dwell time without the usage of filters, via a continuous cascade observer. Moreover, it allows to generate a continuous control signal that is turn on after the observer has converged, guaranteeing theoretically exact compensation of the matched uncertainties/perturbations before the dwell time.
Ghost: Voronoi-based tracking in sparse wireless networks using virtual nodes
Telecommunication Systems
https://doi.org/10.1007/s11235-015-0046-1
Francisco García 1 , Javier Gómez 1 , Marcos A. González 1 , Miguel López Guerrero 2 , Víctor Rangel Licea 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Unidad Iztapalapa

Keywords: Tracking, Voroni tessellation, Sparse wireless networks
Abstract: Conventional tracking techniques for wireless networks locate a target by using at least three non-collinear tracker nodes. However, having such a high density of trackers over the monitored area is not always possible. This paper presents Ghost, a new tracking method based on Voronoi tessellations able to track a target by using less than three tracker nodes in wireless networks. In Ghost, different locations of the target create different Voronoi diagrams of the monitored area by placing virtual nodes around tracker nodes. These diagrams are used to estimate the current location of the target by intersecting the previous and current Voronoi diagrams. The target??s route is constructed by systematically searching the most likely estimated target??s locations over time. Simulation results validate that the proposed method has better tracking accuracy compared with existing proposals. Moreover, our approach is not tied to a specific technology, thus it can be applied in different platforms (e.g., WLAN and WSN).
Theoretical and experimental characterisation of a SAW delay line through its Y-matrix
IET Circuits, Devices & Systems
https://doi.org/10.1049/iet-cds.2016.0038
Jaime Octavio Guerra Pulido 1 , Pablo Roberto Pérez Alcázar 1 , Edgar Álvarez Zauco 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: atomic force microscopy, matrix algebra, scanning electron microscopy, surface acoustic wave delay lines, X-ray diffraction, X-ray fluorescence analysis
Abstract: Surface acoustic wave (SAW) delay lines are commonly used devices, and it is important to characterise them to find the causes of deviations between the experimental and theoretical behaviour in order to consider them during design. The authors present the theoretical characteristics and the characterisation of a SAW delay line through X-ray diffraction, energy dispersive X-ray fluorescence, scanning electron microscopy, atomic force microscopy and the measurement of S -parameters. Using the S -parameters, the Y -parameters were calculated and comparing them with those obtained theoretically, they found disagreement in their magnitudes and also that the experimental SAW velocity was 2.8% larger than the theoretical one. The magnitude of experimental Y11 is smaller than that obtained theoretically because of the ill-defined profile and the metallisation ratio of the electrodes is not ideal due to inherent limitations in the fabrication process, and besides Y21 is smaller than expected because the attenuation of the SAW when it propagates through the delay line. When the electrode defects, the experimental SAW velocity and the attenuation coefficient of SAW in this material are considered in the theoretical calculations, agreement is found between theoretical and experimental results. This procedure is based in the comparison between experimental and theoretical Y -parameters and could be used to estimate attenuation, electrode capacitance and SAW velocity.
Control de Fuerza de Robots Manipuladores Basado en Observadores Proporcionales Integrales Generalizados
Revista Iberoamericana de Automática e Informática Industrial
https://doi.org/10.1016/j.riai.2016.01.004
Alejandro Gutiérrez Giles 1 , Marco Antonio Arteaga Pérez 2 , Hebertt Sira Ramírez 3
1 University of Naples Federico II, CREATE Consortium and Prisma Laboratory
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados

Keywords: Control de fuerza, Control de posición, manipuladores robóticos, observadores de estados, control robusto
Abstract: En este trabajo se presenta el diseño de un controlador lineal robusto para el seguimiento simultáneo de posición y fuerza de robots manipuladores completamente actuados. Las no linealidades aditivas, posiblemente dependientes del estado, se modelan como una perturbación variante en el tiempo absolutamente acotada. Los observadores Proporcionales Integrales Generalizados (GPI, por sus siglas en inglés) son capaces de estimar esta perturbación desconocida y un cierto número de sus derivadas temporales de forma aproximada, aunque arbitrariamente cercana. Esta estimaci?o del controlador para cancelar los efectos de los términos desconocidos. Hasta donde los autores saben, los observadores GPI no se han utilizado para el control de fuerza de robots manipuladores. Se presenta un análisis comparativo experimental para mostrar el buen desempeño del esquema propuesto.
Characterization of a Historical Cannonball from the Fortress of San Juan De Ulúa Exposed to a Marine Environment
Archaeometry
https://doi.org/10.1111/arcm.12194
Miguel Ángel Hernández Gallegos 1 , M. Hernández Escampa 1 , C. Abreu 2 , J. Uruchurtu Chavarin 3 , M. Bethencourt 4 , Alba Covelo Villar 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de Vigo, ETSEI
3 Universidad Autónoma del Estado de México, Centro de Investigación en Ingeniería y Ciencias Aplicadas
4 Universidad de Cádiz, Campus de Excelencia Internacional del Mar

Keywords: Archaeometallurgy, metallic characterization, grey cast iron, cannonballs, cupola furnace, Veracruz (Mexico), marine environment
Abstract: Metallurgical analyses and chemical characterizations were carried out on historical cannonballs from the Fortress of San Juan de Ulúa, Veracruz, México. Cannonballs dating from the 18th and 19th centuries share metallurgical characteristics similar to those of material coming from a shipment of ammunition found in the wreck of a sunken French ship from the battle of Trafalgar. The analyses show that the base material is grey cast iron with a carbon equivalent of 4.94 and a ferritic??perlitic matrix, in which the high phosphorus content has led to the formation of iron phosphide compounds in conjunction with a homogeneous distribution of carbon graphite flakes of Type C. In addition, corrosion products from samples revealed the presence of various crystalline iron compounds (X?ray diffraction), mostly highly chlorinated iron compounds identified as akaganeite. X?ray fluorescence identified various characteristics of the corrosion products as a function of the sampling depth. FT??IR spectroscopy revealed that the main difference between the corrosion products (internal and external) is determined by the number of organic species. Differential scanning calorimetry corroborated that these corrosion products are thermally stable compounds at elevated temperatures.
Understanding the Interrelationship Between Global Terrorist Attacks and the Citizen??s Wellbeing: The Complexity of Terrorism
Sociology Study
https://doi.org/10.17265/2159-5526/2016.05.001
Aida Huerta Barrientos 1 , Pablo Padilla Longoria 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Investigación en Matemáticas Aplicadas y Sistemas

Keywords: Terrorist attacks, national wellbeing, global governance, corruption, drugs
Abstract: Terrorism is a global phenomenon that over the last 44 years more than 140,000 terrorist events have been carried out. In the period from 1970-2001, the five countries with the largest number of terrorist attacks were Colombia, Peru, El Salvador, United Kingdom, and India. On the other hand, in the post-2001 context, the five countries with the largest number of terrorist attacks were Iraq, Pakistan, Afghanistan, India, and Thailand. One method for measuring in an aggregate way, how many people have suffered under terrorist attacks at national level is to analyze the correlation between some national wellbeing indicators and the number of terrorist attacks. The aim of this study is to analyze empirically the correlation between the global terrorist attacks and the countries wellbeing indicators. Five indicators show a strong relationship with the number of terrorist attacks in the case of the four most attacked countries in the post-2001 context. The authors consider that their findings can support the design of new strategies for preventing terrorist activities taking into account certain socio-economic and political drivers. The authors conclude that as such drivers are socio-complex, so it is necessary to adopt the complex adaptive system (CAS) approach to provide a new way of thinking about terrorism.
Indentation Curves in Viscoplastic Alloys: Mathematical Model, Fitting Procedures, and Application to the Room-Temperature Creep of an Al-Sn Alloy
Advances in Materials Science and Engineering
https://doi.org/10.1155/2016/6909854
Víctor Hugo Jacobo Armendáriz 1 , Armando Ortiz Prado 1 , Rafael Schouwenaars Franssens 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: Hardness is an important design parameter but, in rate-dependent materials, its value depends on the indentation speed and dwell time during measurement. Dimensional analysis for indentation testing provides rigorous descriptions for the load-displacement curves of elastoplastic materials; viscoplastic materials can be treated likewise by neglecting the plastic part of the deformation, which is not accurate for most engineering alloys. This work presents a methodology for constructing model indentation curves taking into account concurrent viscous and plastic strains, as well as corrections for tip roundness, load frame compliance, and the point of first contact. A procedure is presented to calculate the parameters of a single model curve by fitting to multiple experimental curves, incorporating the numerical solutions of the differential equation describing viscoplastic behaviour. The procedure is applied to Vickers indentation in brass and steel calibration blocks and to a SAE783 Al-Sn alloy for journal bearings, where creep at room temperature is observed. The soundness of the approach is demonstrated by the large reduction of statistical uncertainty on the parameters describing the indentation curves. A rate-independent hardness will be found and a brief comment is provided on the comparison between creep analysis by indentation and uniaxial tension.
Start-up electroosmotic flow of Maxwell fluids in a rectangular microchannel with high zeta potentials
Journal of Non-Newtonian Fluid Mechanics
https://doi.org/10.1016/j.jnnfm.2015.11.003
Edson M. Jiménez 1 , Juan P. Escandón Colín 2 , Oscar Eladio Bautista Godínez 2 , Federico Méndez Lavielle 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Transient electroosmotic flow, Maxwell fluids, Rectangular microchannel, Field effects
Abstract: In this paper, the start-up from rest of the electroosmotic flow of Maxwell fluids in a rectangular microchannel with asymmetric high zeta potentials at the walls is studied. By appropriately combining the momentum equation with the rheological Maxwell model, a hyperbolic partial differential equation to determine the flow field is obtained. The dimensionless mathematical model is solved using Green??s functions and the separation-of-variables method. Because the high zeta potentials at the walls of the microchannel are taken into account, the electrical potential distribution is numerically solved. We show that the flow is characterized by two relevant parameters that control the electroosmotic flow: the dimensionless relaxation time of the viscoelastic fluid, l1 and the dimensionless zeta potentials of the walls,xi. The most important results of this paperare that the required time to reach the steady state depends on the assumed values of the relaxation time and that the velocity profiles exhibit a singular transient oscillatory behavior because of the competition between viscous, elastic and electroosmotic forces. For asserting the correctness of the semi-analytical solution of the electroosmotic flow, an analytical solution was determined by considering low zeta potential, and a very good agreement between them was found.
Continuous terminal sliding-mode controller
Automatica
https://doi.org/10.1016/j.automatica.2016.02.001
Shyam Kamal 1 , Jaime Alberto Moreno Pérez 2 , Asif Chalanga 1 , Bijnan Bandyopadhyay 1 , Leonid Fridman Golredich 3
1 Indian Institute of Technology, Systems and Control Engineering
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Third-order sliding-mode, Finite time stability, Lyapunov stability
Abstract: For uncertain systems with relative degree two, a continuous homogeneous sliding-mode control algorithm is proposed. This algorithm ensures finite-time convergence to the third-order sliding set, using only information about the output and its first derivative. We prove the convergence of the proposed algorithm via a homogeneous, continuously differentiable and strict Lyapunov function.
Fuel depletion analysis of a small sodium fast reactor with KANEXT and SERPENT
Annals of Nuclear Energy
https://doi.org/10.1016/j.anucene.2016.07.024
Roberto López Solis 1 , Juan Luis François Lacouture 2 , Guillermo Elías Bastida Ortiz 2 , Maarten Becker 3 , Víctor Hugo Sánchez Espinoza 3
1 Instituto Nacional de Investigaciones Nucleares
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Karlsruhe Institute of Technology, Institute for Neutron Physics and Reactor, Technology

Keywords: Sodium cooled fast reactor, Depletion calculations, KANEXT, SERPENT
Abstract: Sodium cooled fast reactors are one of the systems considered as candidates in the Generation IV Forum. As most of Generation-IV systems are under development, efficient and reliable computational tools are needed to obtain accurate results in a reasonable computer time. In this work, the KArlsruhe Neutronic EXtended Tool (KANEXT), which is a modular code system for deterministic reactor calculations consisting of one kernel and several modules, is introduced and compared against the Monte Carlo SERPENT code, for fuel depletion calculations of a small core of a sodium fast reactor (SFR). The sodium fast reactor particularities, important for the core analysis, are described, and the model assumptions made for both codes are explained. Selected parameters, e.g. the effective neutron multiplication factor, the isotopes inventory and axial and radial power distributions against burnup are compared. The results of these comparisons show a very good agreement between the transport P3 solution of KANEXT and SERPENT.
Effect of mineral aggregates on the morphology and viability of Toxocara canis eggs
Ecological Engineering
https://doi.org/10.1016/j.ecoleng.2016.01.071
Rafael Magaña López 1 , Víctor Manuel Luna Pabello 1 , José Antonio Barrera Godínez 1 , María Teresa Orta De Velásquez 2 , Georgina Fernández Villagómez 3
1 Universidad Nacional Autónoma de México, Facultad de Química
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Mineral aggregate, Morphological damage, Helminth egg, Viability loss, Metal, Toxocara canis
Abstract: This work shows the effects on morphology and inactivation or viability loss on Toxocara canis eggs (TCE) as a result of their direct exposure to mineral aggregates (MA). Contact assays were performed on TCE-MA in flasks using 15 TCE per sample, and MA (0.01, 0.05, 0.1, 0.5, 1, and 2 g mL??1) for exposure times of 30, 60, 90, and 120 min, under shaking (US), and no shaking (NS) conditions. The MA characterization was performed by X-Ray Diffraction Spectroscopy (XRDS), Mass Absorption Spectroscopy with Graphite Furnace (MASGF), Coupled Plasma Mass Spectrometry (ICP-MS), and X-Ray Fluorescence Spectrometry (XRF). MA are composed of hematite, sandinite, montmorillonite, calcite, quartz, nimite, and jordanite. The composition of the residue on ignition (mg kg??1) was: CaO (91,746.0 ± 1913.7), Zr (2542.8 ± 131.2), Al2O3 (1683.0 ± 209.3), SiO2 (1138.0 ± 123.5), as well as Fe2O3 (212.0 ± 23.1), Cu (0.2 ± 0.4), TiO2 (36.4 ± 6.1), and Ag (128.0 ± 1.4). In order to identify the morphological alterations associated with the TCE viability loss in the contact assays, photo-micrographs were taken by an optical microscope (OM) and a scanning electron microscope (SEM). These experiments showed structural damage on the external and internal layers (nucleus and hyaline solution) of the TCE, indicating a direct relationship with the viability loss or inactivation; the observed values were in the range of 35% (0.01 g of 2 mm MA; 30 min; NS) up to 92% (2.00 g of 0.6 mm MA; 120 min; US). The viability loss increases as the MA particle size decreases, and as the MA concentration increases, the effect of the time of contact and the shaking condition also affect the viability loss. The external morphological damage observed on TCE includes impairment, thinning, and fracture of the external layers. On the internal structures, heterogeneity of the hyaline solution and release of the nuclear material were observed. Consequently, the TCE viability loss can be attributed to the structural damage caused by the mechanical stress produced by direct contact with the MA surface. This damage is synergistic with the interaction caused by the chemical stress between the TCE biomass and the MA. Certain compounds of the MA, containing Ag, Cu, Fe, Al, Ti and Zn, have been reported as having biocidal ability.
Viscoelectric effect on electroosmotic flow in a cylindrical microcapillary
Fluid Dynamics Research
https://doi.org/10.1088/0169-5983/48/3/035503
J. Marroquín Desentis 1 , Federico Méndez Lavielle 2 , Oscar Eladio Bautista Godínez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: Electroosmotic flow, under the Debye??Hückel approximation, has been widely analyzed in the specialized literature. This is a severe restriction in practice, where zeta potentials as high as 100??200 mV are encountered frequently. Under this condition, the variation of the viscosity with the electric field in the electric double layer (EDL), known as the viscoelectric effect, can lead to a considerable variation in comparison to the Helmholtz??Smoluchowsky equation for the electroosmotic velocity. The objective of this work is to analyze the electroosmotic flow in a cylindrical capillary at high zeta potentials in the thin EDL approximation, taking into account the viscoelectric effect. In order to obtain the potential distribution, the Poisson??Boltzmann equation was solved by using the matched asymptotic expansions method, and then, by applying the same technique, the flow field was determined from the momentum equation by considering that the viscosity of the electrolyte changes according to the relationship $\eta ={\eta }_{0}[1+{{fE}}^{2}]$, where ${\eta }_{0}$ is the viscosity evaluated in the absence of an electric field, f is the viscoelectric constant and E is the intrinsic electric field in direction transversal to the EDL. For asserting the correctness of the asymptotic solution, this result was compared against a numerical solution, and a very good agreement between them was found. The results show that the viscoelectric effect has a noticeable influence by reducing the electroosmotic flow velocity in about 10% in comparison to the standard Helmholtz??Smoluchowski velocity.
Effect of heat transfer correlations on the fuel temperature prediction of SCWRs
European Journal of Physics N
https://doi.org/10.1051/epjn/2016030
Erick Gilberto Espinosa Martínez 1 , Cecilia Martín del Campo 1 , Juan Luis François Lacouture 1 , Gilberto Espinosa Paredes 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos

Keywords:
Abstract: In this paper, we present a numerical analysis of the effect of different heat transfer correlations on the prediction of the cladding wall temperature in a supercritical water reactor at nominal operating conditions. The neutronics process with temperature feedback effects, the heat transfer in the fuel rod, and the thermal-hydraulics in the core were simulated with a three-pass core design.
Minimal global regret analysis for electricity generation expansion
Energy Sources, Part B: Economics, Planning, and Policy
https://doi.org/10.1080/15567249.2011.632808
Cecilia Martín del Campo 1 , Juan Luis François Lacouture 1 , Guillermo José Estrada 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Decision analysis, electricity expansion planning, long-term planning, Mexican electricity generation, Position Vector of Minimum Regret Analysis
Abstract: A comparative assessment of alternative expansion plans for the Mexican electricity generation system was made by applying the Position Vector of Minimum Regret Analysis as a decision tool. The expansion plans were ranked according to seven decision criteria which consider: internal cost, risk, diversity, external cost, foreign capital fraction, carbon-free fraction, and severe accidents. Electricity expansions were optimized by using the WASP-IV model; internal costs and externalities over a long-term planning horizon were simultaneously minimized when the external cost was added into the variable component of the operation and maintenance cost. Special attention was paid to studying the convenience of including nuclear power in the electricity expansion. The new decision analysis tool ranked the plans in terms of the minimum global regret, and results showed that the plans which added nuclear power plants were in general relatively more attractive than the plans that did not.
Good selection
Electronic Letters
https://doi.org/10.1049/el.2016.1153
Henry Fabian Gongora 1 , Alexander Martynyuk 1 , Jorge Rodríguez Cuevas 1 , José Ismael Martínez López 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: frequency selective surfaces, radio networks, frequency allocation, indoor radio, telecommunication security
Abstract: Perhaps the best known frequency selective surface (FSS) is the screen on a microwave oven window. It allows the transmission of optical frequencies, so that you can observe the cooking of the food while preventing any harmful microwave fields from escaping. However, most of the applications of FSSs are in radar and telecommunications systems. FSSs have been extensively used as radomes, subreflectors, polarisers and metamaterials. More recently, due to the high demand of wireless indoor systems in offices, FSSs have been used in the electromagnetic architecture of buildings to enhance the spectral efficiency via frequency reuse and to improve the security of wireless networks. A FSS is commonly a two dimensional (2-D) periodic array, composed of either metallic patches on a dielectric substrate or apertures on a conductive screen, and it acts as a spatial filter for electromagnetic waves. FSSs can be designed to provide either low pass, high pass, band pass or band stop behaviour. The shape of the patch or the aperture, the dimensions of the FSS unit cell, the materials used, as well as the array lattice, determine the frequency response of the overall FSS.
Fiber optic refractometric sensors using a semi-ellipsoidal sensing element
Applied Optics
https://doi.org/10.1364/AO.55.002574
Amalia Nallely Castro Martínez 1 , Matej Komanec 2 , Tomas Nemecek 2 , Stanislav Zvanovec 2 , Sergei Khotiaintsev 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Czech Technical University, Faculty of Electrical Engineering

Keywords:
Abstract: We present theoretical and experimental results for a fiber optic refractometric sensor employing a semi-ellipsoidal sensing element made of polymethyl methacrylate. The double internal reflection of light inside the element provides sensitivity to the refractive index of the external analyte. We demonstrate that the developed sensor, operating at a wavelength of 632 nm, is capable of measurement within a wide range of refractive indices from ??=1.00 to ??=1.47 with sensitivity over 500 dB/RIU. A comparison of the developed sensor with two more complex refractometric sensors, one based on tapered optical fiber and the other based on suspended-core microstructure optical fiber, is presented.
Electroosmotic flow of a Phan-Thien??Tanner fluid in a wavy-wall microchannel
Colloids and Surfaces A: Physicochemical and Engineering Aspects
https://doi.org/10.1016/j.colsurfa.2016.02.036
Leticia López Martínez 1 , Oscar Eladio Bautista Godínez 2 , Juan P. Escandón Colín 2 , Federico Méndez Lavielle 3
1 Instituto Politécnico Nacional, ESIME Azcapotzalco
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Wavy-wall microchannel, Electroosmotic flow, Phan-Thien??Tanner fluid, Domain perturbation method
Abstract: In this paper the electroosmotic flow (EOF) of a viscoelastic fluid in a wavy-wall microchannel is asymptotically analyzed. The rheological behavior of the fluid corresponds to the simplified Phan-Thien??Tanner model (sPTT). By using the lubrication theory, the governing equations of the flow are considerably simplified, which are written in dimensionless form. For obtaining the solution for the flow and electric fields, and assuming small amplitudes of the waviness of the microchannel walls, the domain perturbation method is used. The EOF is mainly characterized by the following dimensionless parameters: Δ modulates the waviness of the walls; n denotes the number of waves along the microchannel and ?, which reflects the viscoelastic character of the fluid. The principal results show that the volumetric flow rate is increased when ? is increased, due to this parameter influences in an important manner on the velocity gradient at the microchannel wall. Also, for very small values of Δ, the volumetric flow rate increases linearly. In contrast, for increasing values of n, the volumetric flow rate diminishes.
Dual-Frequency Reflectarray Based on Split-Ring Slots
IEEE Antennas and Wireless Propagation Letters
https://doi.org/10.1109/LAWP.2016.2615049
Jesús Ortiz Fuentes 1 , Jovanni Silva Montero 1 , José Ismael Martínez López 1 , Jorge Rodríguez Cuevas 1 , Alexander Martynyuk 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Aperture efficiency, cross polarization, dual-frequency, dual-resonant, reflectarrays (RAs)
Abstract: This letter presents a dual-frequency reflectarray (RA). This RA is capable of forming two differently oriented main lobes with the same sense of circular polarization in the directions determined by the reflection elevation angles θ 01 and θ 02 at two closely spaced frequencies. The RA element contains a pair of concentric split-ring slots with different angular rotations. The geometry of the element was modified and optimized to suppress a mutual coupling between the concentric rings. To validate the operation principle, 317-element offset RAs RA_0_20, RA_20_0, RA_30_40, and RA_40_30 were designed to operate at 34.5 and 38.5 GHz for the pairs of elevation angles (θ 01 , θ 02 ) equal to (0°, 20°), (20°, 0°), (30°, 40°), and (40°, 30°), respectively. Then, these RAs were fabricated and tested. The highest measured aperture efficiency of 0.45 was observed for RA_0_20 and RA_20_0 at 34.2 GHz, whereas the RA_30_40 demonstrated the lowest aperture efficiency of 0.25 at 38.2 GHz.
DRM Reception Results in Long-Range Short Wave Broadcasting
IEEE Latin America Transactions
https://doi.org/10.1109/TLA.2016.7430062
José María Matías Maruri 1 , I. Peña 1 , F.F. Lima 2 , M. A. Hernández 1 , Víctor García Garduño 1 , H. A. 3 , A. A. Menezes 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de Brasilia, Ministerio das Comun de Brazil
3 Universidad de Brasilia, Departamento de Ingeniería den Telecomunicaciones
4 Universidad de Brasilia, Facultad Anhanguera

Keywords: digital audio broadcasting, Digital radio, Digital Radio Mondiale, DRM, field trials, Short Wave
Abstract: The Digital Radio Mondiale (DRM) digital radio standard is the only one recommended by the ITU to be used in Short Wave bands. These bands present unique characteristics for the broadcasting, very big coverage areas and long-range transmission. But they suffer of complicated propagation channel with big time variations that make difficult the regular broadcasting operation. In order to evaluate the DRM performance, field trials were made in Brazil by the Brazilian Government. The objective was to evaluate DRM technology for long-range transmission in Short Wave frequencies. In this paper, the results of these field trials are explained. Two frequencies were used during a period of three weeks at different hours of the day. The transmission was made from French Guyana and the reception was tested in Brasilia.
Asymptotic analysis of the interaction between linear long waves and a submerged floating breakwater of wavy surfaces
Applied Ocean Research
https://doi.org/10.1016/j.apor.2016.06.002
Ayrton Alfonso Medina Rodríguez 1 , Federico Méndez Lavielle 2 , Eric Gustavo Bautista Godínez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Submerged breakwater, Shallow flow, Domain perturbation method, Wavy surface, Wave reflection
Abstract: In this work, we carried out an asymptotic analysis, up to the second order in a regular expansion, of the interaction of linear long waves with an impermeable, fixed, submerged breakwater composed of wavy surfaces. Below the floating breakwater, there is also a step with a wavy surface. The undulating surfaces are described by sinusoidal profiles. The effects of three different geometric parameters ?? the amplitude of the wavy surfaces and the submerged length and width of the structure ?? on the reflection and transmission coefficients are analyzed. The hydrodynamic forces are also determined. The governing equations are expressed in dimensionless form. Using the domain perturbation method, the small wavy surfaces of the breakwater are linearized. The wavy surfaces of the breakwater generate larger values of the reflection coefficient than those obtained for breakwaters with flat surfaces, and the largest values of this coefficient are obtained when the length of the breakwater is of the same order of magnitude as the wavelength. The asymptotic solution is compared with the theoretical solutions that have been reported in the specialized literature and with a numerical solution. The present mathematical model can be used as a practical reference for the selection of the geometric configuration of a submerged floating breakwater under shallow flow conditions.
SAR observations of the Nansen Ice Shelf fracture
The European Physical Journal Plus
https://doi.org/10.1140/epjp/i2016-16384-y
Miguel Moctezuma Flores 1 , Flavio Parmiggiani 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Institute of Atmospheric Sciences and Climate, Bologna

Keywords:
Abstract: This paper presents a study, by means of of Synthetic Aperture Radar (SAR) images, of the fracture of the Nansen Ice Shelf, from its first appearance in SAR images to the final collapse on 7 April 2016. Both Sentinel-1 and Cosmo-SkyMed images have been used. First, the images were remapped onto an equidistant cylindrical projection; from these a subset, or imagette, only covering the fracture was extracted. A segmentation scheme was then applied to the sequence of imagettes in order to produce a sequence of binary imagettes with only the fracture area enhanced; from these, the computation of fracture area became a trivial task.
Optimization of the synthesis process of an iron oxide nanocatalyst supported on activated carbon for the inactivation of Ascaris eggs in water using the heterogeneous Fenton-like reaction
Water Science and Technology
https://doi.org/10.2166/wst.2015.576
Ariadna A. Morales Pérez 1 , Pablo Maravilla 2 , Myriam Solís López 1 , Rafael Schouwenaars Franssens 3 , Alfonso Durán Moreno 4 , Rosa María Ramírez Zamora 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Hospital General Dr. Manuel Gea González, Departamento de Ecología de Agentes Patógenos
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Nacional Autónoma de México, Facultad de Química

Keywords: Ascaris inactivation, experimental design, Fenton reaction, helminth egg, iron nanoparticles
Abstract: An experimental design methodology was used to optimize the synthesis of an iron-supported nanocatalyst as well as the inactivation process of Ascaris eggs (Ae) using this material. A factor screening design was used for identifying the significant experimental factors for nanocatalyst support (supported %Fe, (w/w), temperature and time of calcination) and for the inactivation process called the heterogeneous Fenton-like reaction (H2O2 dose, mass ratio Fe/H2O2, pH and reaction time). The optimization of the significant factors was carried out using a face-centered central composite design. The optimal operating conditions for both processes were estimated with a statistical model and implemented experimentally with five replicates. The predicted value of the Ae inactivation rate was close to the laboratory results. At the optimal operating conditions of the nanocatalyst production and Ae inactivation process, the Ascaris ova showed genomic damage to the point that no cell reparation was possible showing that this advanced oxidation process was highly efficient for inactivating this pathogen.
Adaptive continuous twisting algorithm
International Journal of Control
https://doi.org/10.1080/00207179.2015.1116713
Jaime Alberto Moreno Pérez 1 , Daniel Negrete 2 , Víctor Torres González 2 , Leonid Fridman Golredich 2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Sliding mode control, adaptive control
Abstract: In this paper, an adaptive continuous twisting algorithm (ACTA) is presented. For double integrator, ACTA produces a continuous control signal ensuring finite time convergence of the states to zero. Moreover, the control signal generated by ACTA compensates the Lipschitz perturbation in finite time, i.e. its value converges to the opposite value of the perturbation. ACTA also keeps its convergence properties, even in the case that the upper bound of the derivative of the perturbation exists, but it is unknown.
Acquisition and digital filtering for epithelial potential of breast via Matlab user interface
International Journal of Engineering Science and Innovative Technology
http://www.ijesit.com/archive/26/volume-5issue-1-january-2016.html
Fátima Moumtadi 1 , Sergio Meléndez Armas 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: biopotentials, user interface, bioelectrical signal filtering, epithelial potential difference, signal acquisition, electric potential
Abstract: this article describes the development of a user interface for a reading device of potential differences in the epithelial surface of the female breast. This device consists of an array of 24 electrodes and signal acquisition card capable of taking a range of reading of 31.25[µV] to 1.024[V]. An analysis of the bioelectrical signal present in the breast of the woman took place and digital filtering thereof
Design and Performance Evaluation of DWDM Links: The Case of Metropolitan Delta Network Extension for Research and Education in Mexico
International Journal of Information and Electronics Engineering
10.18178/IJIEE.2016.6.5.647
Pedro Jesús Nájera Chávez 1 , Aida Huerta Barrientos 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Delta network, DWDM design, DWDM performance evaluation, research and education network
Abstract: The Delta Metropolitan academic network is a fiber-optic networks that interconnects high performance supercomputing clusters of National Autonomous University of Mexico (UNAM), Autonomous Metropolitan University (UAM) and Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV-IPN). The aim of this paper is to design DWDM links and evaluate the optic receiver performance to connecting additional academic institutions as the Faculties of Higher Studies (FES) of UNAM to the Delta Metropolitan academic network. The four selected FES are Zaragoza, Aragon, Iztacala and Cuautitlan, so the DWDM links designed are FES Zaragoza-UNAM, FES Aragon-UNAM, FES Iztacala-UNAM and FES Cuautitlan-UNAM. We calculate the power budget for the four fiber-optic links. Then we analyze the DWDM receiver performance through the eye diagram tool. Our results show that from the technical perspective the four DWDM links designed are feasible to be installed.
Participation of the Olfactory Bulb in Circadian Organization during Early Postnatal Life in Rabbits
Plos One
https://doi.org/10.1371/journal.pone.0156539
Erika Navarrete 1 , Juan Roberto Ortega Bernal 1 , Lucero Trejo Muñoz 1 , Georgina Díaz 1 , Rodrigo Montúfar Chaveznava 2 , Ivette Caldelas 1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomédicas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: Experimental evidence indicates that during pre-visual stages of development in mammals, circadian regulation is still not under the control of the light-entrainable hypothalamic pacemaker, raising the possibility that the circadian rhythmicity that occurs during postnatal development is under the control of peripheral oscillators, such as the main olfactory bulb (MOB). We evaluated the outcome of olfactory bulbectomy on the temporal pattern of core body temperature and gross locomotor activity in newborn rabbits. From postnatal day 1 (P1), pups were randomly assigned to one of the following conditions: intact pups (INT), intact pups fed by enteral gavage (INT+ENT), sham operated pups (SHAM), pups with unilateral lesions of the olfactory bulb (OBx-UNI), and pups with bilateral lesions of the olfactory bulb (OBx-BI). At the beginning of the experiment, from P1-8, the animals in all groups were fed at 11:00, from P9-13 the feeding schedule was delayed 6 h (17:00), and finally, from P14-15 the animals were subjected to fasting conditions. The rabbit pups of the INT, INT+ENT, SHAM and OBx-UNI groups exhibited a clear circadian rhythmicity in body temperature and locomotor activity, with a conspicuous anticipatory rise hours prior to the nursing or feeding schedule, which persisted even during fasting conditions. In addition, phase delays in the nursing or feeding schedule induced a clear phase shift in both parameters. In contrast, the OBx-BI group exhibited atypical rhythmicity in both parameters under entrained conditions that altered the anticipatory component, as well as deficient phase control of both rhythms. The present results demonstrate that the expression of circadian rhythmicity at behavioral and physiological levels during early stages of rabbit development largely depends on the integrity of the main olfactory bulb.
Development of a Leading Performance Indicator from Operational Experience and Resilience in a Nuclear Power Plant
Nuclear Engineering and Technology
https://doi.org/10.1016/j.net.2015.10.010
Pamela Nelson 1 , Cecilia Martín del Campo 1 , Bruce Hallbert 2 , Araliya Mosleh 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Idaho National Laboratory, Nuclear Energy Enabling Technologies
3 University of California, Los Angeles, B. John Garrick Institute for the Risk Sciences

Keywords: Condition adverse to quality, Corrective action program, Leading performance indicators, Organizational factors, Problem Identification and resolution program, Resilience
Abstract: The development of operational performance indicators is of utmost importance for nuclear power plants, since they measure, track, and trend plant operation. Leading indicators are ideal for reducing the likelihood of consequential events. This paper describes the operational data analysis of the information contained in the Corrective Action Program. The methodology considers human error and organizational factors because of their large contribution to consequential events. The results include a tool developed from the data to be used for the identification, prediction, and reduction of the likelihood of significant consequential events. This tool is based on the resilience curve that was built from the plant's operational data. The stress is described by the number of unresolved condition reports. The strain is represented by the number of preventive maintenance tasks and other periodic work activities (i.e., baseline activities), as well as, closing open corrective actions assigned to different departments to resolve the condition reports (i.e., corrective action workload). Beyond the identified resilience threshold, the stress exceeds the station's ability to operate successfully and there is an increased likelihood that a consequential event will occur. A performance indicator is proposed to reduce the likelihood of consequential events at nuclear power plants.
The flow inside shaking flasks and its implication for mycelial cultures
Chemical Engineering Science
https://doi.org/10.1016/j.ces.2016.06.016
Carlos Alberto Palacios Morales 1 , Juan Pablo Aguayo Vallejo 2 , Mauricio A. Trujillo Roldán 3 , Roberto Zenit 4 , Gabriel Ascanio 2 , Marisol Soledad Córdova Aguilar 5
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, Instituto de Investigaciones Biomédicas
4 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
5 Universidad Nacional Autónoma de México, Centro de Ciencias Aplicadas y Desarrollo Tecnológico

Keywords: Shake flasks, PIV technique, Flow patterns, Streptomyces lividans
Abstract: Several parameters such as mixing time, power consumption and deformation rates have been commonly reported in the literature for the hydrodynamic characterization of shaken flasks. In the present work, flow fields of orbital shaken flasks having different geometries have been experimentally obtained. Conventional, baffled and coiled flasks were tested at constant shaking speed of 150 rpm at which the cultures are grown. Flow fields in terms of turbulence intensity and deformation rate were both determined by means of the Particle Image Velocimetry (PIV) technique. Velocity fields are strongly dependent on the flask geometry; in particular, the main flow is confined near the wall for the conventional geometry. In general, large velocity fluctuations are found in the whole flask for the baffled and coiled geometries, while the turbulence intensity is virtually zero at the center region for the conventional flask. The measurement of the average deformation rate indicates that flow obstacles, such as indentations and coiled springs, generate regions with high hydrodynamic stresses promoting the elongation and breakup of bubbles and biomass. Results from this study have been compared with previous studies finding good agreement for the same flask configurations at similar experimental conditions.
Phase-Change Transpiration Cooling in a Porous Medium: Determination of the Liquid/Two-Phase/Vapor Interfaces as a Problem of Eigenvalues
Transport in Porous Media
https://doi.org/10.1007/s11242-016-0637-7
M. Peralta 1 , Federico Méndez Lavielle 2 , Oscar Eladio Bautista Godínez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Transpiration cooling, porous media, coolant phase change, eigenvalues
Abstract: In this work, we carry out a theoretical analysis of the transpiration cooling with a liquid coolant phase change in a porous medium. The evaporation of the liquid inside the porous medium causes the appearance of three regions: a liquid region, a two-phase region and a vapor region. This kind of physical problem has been widely studied in the specialized literature and the main contributions are based on the separated phase model or by using the two-phase mixture model. Here, we propose a new model that permits to numerically determine the thickness of the three regions that are formed inside of the porous medium. To analyze this phenomenon, the governing equations were appropriately nondimensionalized, where suitable Péclet numbers for each region appear such that these numbers represent eigenvalues for the mathematical model, and when they are obtained, the relative position of the interfaces between each region is found.
Simulation of Fault-Tolerant Space Systems Based on COTS Devices With GPSS
IEEE Systems Journal
https://doi.org/10.1109/JSYST.2014.2338212
Juan Andres Pérez Celis 1 , Jorge Ferrer Pérez 1 , Saúl Daniel Santillán Gutiérrez 1 , Saúl De la Rosa Nieves 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fault tolerance, field-programmable gate array (FPGA), general-purpose system simulation (GPSS), microsatellite, reliability, simulation, space systems
Abstract: In microsatellite missions devoted to remote sensing, the cost-reliability issue is an important constraint. This paper presents a low-cost methodology to simulate the reliability of a system for the development of fault-tolerant space systems. This methodology does not rely on special facilities or expensive equipment and is focused on the onboard data handling (OBDH) system for microsatellite's remote sensing payloads with commercial off-the-shelf components. The method presented uses the general-purpose simulation system language to simulate the system's reliability when fault-tolerance techniques (FTTs) are applied to field-programmable gate arrays. The objective of the proposed methodology is to validate the mathematical model corresponding to the system's reliability or to compute the reliability when there is no mathematical model. Therefore, system-level decisions can be made, in order to select the most suitable components and develop the systems for microsatellites. Specifically, the OBDH computers must have a high reliability as a mandatory requirement for microsatellites. Moreover, the simulation provides statistics to support decisions regarding the necessary FTT to be implemented.
Optimisation and analysis of the synthesis of a cellular glass-ceramic produced from water purification sludge and clay
Applied Clay Science
https://doi.org/10.1016/j.clay.2015.11.012
Rosa María Ramírez Zamora 1 , Fabricio Espejel Ayala 2 , Myriam Solís López 1 , Oscar González Barceló 1 , Raúl Gómez 3 , José Luis Pérez Mazariego 3 , Rafael Navarro González 3 , Rafael Schouwenaars Franssens 4
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Electroquimica, Centro de Investigación y Desarrollo Tecnológico
3 Universidad Nacional Autónoma de México, Facultad de Ciencias
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Ceramic foam, Kaolinite, Sludge, Thermogravimetry, Mössbauer spectroscopy, XRD
Abstract: The sludge generated in the treatment of surface water for human consumption represents an environmental hazard which can be mitigated by the valorisation of this solid waste. This paper presents an analysis of the process parameters and physicochemical mechanisms involved in the elaboration of a glass-ceramic foam using clay and the sludge generated in a drinking water plant. Optimisation of the process conditions was performed by a 33 experimental design. For structural purposes, compression strength is the optimising parameter; if used as a catalytic support or filtering medium, porosity and permeability have to be maximised. An open cellular structure can be obtained when the materials are fired in a mould which allows the coexistence of solid, liquid and gas phases. The latter are responsible for foaming and were identified as CO2, SO2 and H2O. Thermogravimetric analysis coupled to mass spectrometry and Mössbauer spectroscopy show that CO2 was generated mainly from pyrolysis, SO2 was generated from aluminium sulphate used as a coagulant in the drinking water treatment but H2O resulting from the decomposition of lepidocrocite at high temperature is likely to be the main agent for the foaming effect.
Geochronology of Mexican mineral deposits. IV: the Cinco Minas epithermal deposit, Jalisco
Boletín de la Sociedad Geológica Mexicana
https://doi.org/10.18268/BSGM2016v68n2a12
Antoni Camprubi 1 , Alexander Iriondo 2 , Margarita López Martínez 3 , Aldo Ramos Rosique 4
1 Universidad Nacional Autónoma de México, Instituto de Geología
2 Universidad Nacional Autónoma de México, Centro de Geociencias
3 Centro de Investigación Científica y de Educación Superior de Ensenada
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Cinco Minas, Mexico, epithermal deposits, low sulfidation, 40Ar/39Ar ages, adularia
Abstract: Two 40Ar/39Ar ages at 24.50 ± 0.07 and 23.46 ± 0.26 Ma (latest Oligocene) were obtained in this paper for adularia separates from vein material of the Cinco Minas low sulfidation epithermal deposit in Jalisco, southwestern Mexico. Such ages confirm the migration of metallogenic activity along with volcanism as the Sierra Madre Occidental migrated southwards since the latest Oligocene and into the Miocene. These deposits are synchronous to andesitic volcanism nearby. In addition, these ages indicate the occurrence of epithermal mineralization prior to the climactic event of ignimbrite flare-up in the Miocene. This makes necessary to refine previous ideas in the metallogeny of southwestern Mexico, which suggested a scenario in which the formation of epithermal and other types of hydrothermal deposits in the region were produced almost exclusively as a result of the early Miocene peak episode of volcanism.
Effect of Hydrophobic Coating on Hagen-Poiseuille Flows
Journal of Applied Fluid Mechanics
https://dx.doi.org/10.18869/acadpub.jafm.68.228.24586
A. Ríos Rodríguez 1 , Carlos Alberto Palacios Morales 2 , E. Bernal 1 , Gabriel Ascanio 1 , Juan Pablo Aguayo Vallejo 1
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Slip velocity, PIV visualization, Hagen-poiseuille equation, Drag reduction
Abstract: The effect of a hydrophobic coating on the flow through circular pipes with Newtonian fluids has been investigated. Velocity fields inside a pipe were experimentally determined by the particle image velocimetry (PIV) technique. The test fluid presented a viscosity of about sixty times higher than water viscosity. Two glass pipe configurations were used: one uncoated and another covered with an extremely hydrophobic commercial product. Comparisons between coated and uncoated pipes were made at similar Reynolds (Re) numbers, all in the laminar regime (70-250). Results show that the hydrophobic effect consists in an observable slip velocity at the wall, with a reduction in shear rate near the pipe boundary. Pressure drop values were estimated from a modified Hagen-Poiseuille equation, taking into consideration the non-zero velocity at the boundary for both set of experiments, and the results show a 20% reduction in the pressure drop for the hydrophobic wall compared with the uncoated pipe case.
Homogeneity Based Uniform Stability Analysis for Time-Varying Systems
IEEE Transactions on Automatic Control
https://doi.org/10.1109/TAC.2015.2446371
Héctor Ríos 1 , Denis Efimov 2 , Leonid Fridman Golredich 3 , Jaime Alberto Moreno Pérez 4 , Wilfrid Perruquetti 2
1 INRIA Lille - Nord Europe, Parc Scientifique de la Haute Borne
2 Villenueve d'Ascq, Nord Europe Center
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Time-varying systems, Asymptotic stability, Convergence, Numerical stability, Stability criteria, Robustness
Abstract: The uniform stability notion for a class of nonlinear time-varying systems is studied using the homogeneity framework. It is assumed that the system is weighted homogeneous considering the time variable as a constant parameter, then several conditions of uniform stability for such a class of systems are formulated. The results are applied to the problem of adaptive estimation for a linear system.
Neural Modulation in Aversive Emotion Processing: An Independent Component Analysis Study
Computational and Mathematical Methods in Medicine
https://doi.org/10.1155/2016/2816567
César Romero Rebollar 1 , Luis Jiménez Ángeles 2 , Eduardo Antonio Dragustinovis Ruiz 1 , Verónica Medina Bañuelos 1
1 Universidad Autónoma Metropolitana, Departamento de Ingeniería Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: Emotional processing has an important role in social interaction. We report the findings about the Independent Component Analysis carried out on a fMRI set obtained with a paradigm of face emotional processing. The results showed that an independent component, mainly cerebellar-medial-frontal, had a positive modulation associated with fear processing. Also, another independent component, mainly parahippocampal-prefrontal, showed a negative modulation that could be associated with implicit reappraisal of emotional stimuli. Independent Component Analysis could serve as a method to understand complex cognitive processes and their underlying neural dynamics.
CFD study of constructal microchannel networks for liquid-cooling of electronic devices
Applied Thermal Engineering
https://doi.org/10.1016/j.applthermaleng.2015.11.037
Carlos A. Rubio Jiménez 1 , Abel Hernández Guerrero 2 , Jaime Gonzalo Cervantes De Gortari 3 , Daniel Lorenzini Gutiérrez 2 , C. Ulises González Valle 2
1 Universidad de Guanajuato, Departamento de Energías Renovables
2 Universidad de Guanajuato, Departamento de Ingeniería Mecánica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Microchannel heat sink, Electronics cooling, Constructal design, Flow field, CFD
Abstract: The heat transfer performance of liquid-cooled heat sinks with a constructal design of the flow field configurations is assessed in the present investigation. Y- and Ψ-shaped microfluidic networks embedded on a silicon substrate are numerically analyzed and compared in order to propose an alternative cooling layer for integrated circuits (ICs). The shape, path and geometric dimensions of the flow channels are designed with the Phi number and Allometric scaling laws based on constructal networks, resulting in tree-shaped flow paths with variable hydraulic diameter. The thermal and hydraulic performances of eight different configurations are discussed in terms of the average surface temperature and pressure drop, respectively. Results indicate that the Ψ-shaped heat sink designs offer a higher degree of temperature uniformity than Y-shaped designs, with the penalty of a slightly higher flow restriction. It was observed that the Phi number ratio has a strong effect on thermal performance, with enhanced results for higher ratios. Discussions about heat transfer area, temperature uniformity and pressure drop are given for the different cases, proposing an enhanced design for electronics cooling applications.
Control of discrete time systems based on recurrent Super-Twisting-like algorithm
ISA Transactions
https://doi.org/10.1016/j.isatra.2016.04.024
Iván Salgado 1 , Shyam Kamal 2 , Bijnan Bandyopadhyay 2 , Jorge Isaac Chairez 3 , Leonid Fridman Golredich 4
1 Instituto Politécnico Nacional, Centro de Innovación y Desarrollo Tecnológico en Cómputo
2 Indian Institute of Technology, Systems and Control Engineering
3 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Sliding mode control, Discrete-time super twisting algorithm, Sliding mode differentiator, Electro-mechanical systems
Abstract: Most of the research in sliding mode theory has been carried out to in continuous time to solve the estimation and control problems. However, in discrete time, the results in high order sliding modes have been less developed. In this paper, a discrete time super-twisting-like algorithm (DSTA) was proposed to solve the problems of control and state estimation. The stability proof was developed in terms of the discrete time Lyapunov approach and the linear matrix inequalities theory. The system trajectories were ultimately bounded inside a small region dependent on the sampling period. Simulation results tested the DSTA. The DSTA was applied as a controller for a Furuta pendulum and for a DC motor supplied by a DSTA signal differentiator.
Dynamic modeling of managed pressure drilling applying transient Godunov scheme
Journal of Petroleum Exploration and Production Technology
https://doi.org/10.1007/s13202-015-0176-8
Ángel J. Sánchez Barra 1 , Rubén Nicolás López 2 , Oscar C. Valdiviezo Mijangos 2 , Abel Camacho Galván 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Mexicano del Petróleo

Keywords: Pressure drilling, Oil-well hydraulics, Godunov scheme, Transient pressure, Transient flow
Abstract: Transient hydraulics always characterizes the circulating flow during managed pressure drilling. Therefore, the application of the Godunov scheme to oil-well drilling hydraulics is presented. The numerical model developed describes the treatment process of the initial and boundary conditions from the well geometry and true operational conditions. The well-known finite-volume method and Riemann problem are utilized for building the set of discrete equations. The account of Godunov??s simulation describes the profiles of transient pressure and transient flow rate along the well. For attending the oil-field engineering concerns, the drilling parameters discussed are as follows: choke pressure, pumping pressure, bottom-hole pressure, and circulating flow rate. After the comparison between computed and well data, the results show a small difference of less than 7 and 1 % for pumping and bottom-hole pressures, respectively. The main engineering contribution of this work is the solution and application of the first-order Godunov scheme to analyze the transient hydraulics during actual oil-well drilling and also the analysis and interpretation of the pressure wave behavior traveling along the well. The Godunov scheme has high-potential engineering applications for modeling the transient drilling hydraulics, i.e., controlled flow, underbalanced drilling, and foam cementing, as well.
Adaptive sliding mode control and observation
International Journal of Control
https://doi.org/10.1080/00207179.2016.1194531
Yuri Shtessel 1 , Leonid Fridman Golredich 2 , Frank Plestan 3
1 The University of Alabama, Department of Electrical and Computer Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Institut de Recherche en Communications et Cybernétique de Nantes

Keywords: Sliding mode control, sliding mode observers, adaptive control
Abstract: This editorial article gives a short introduction to Special Issue of International Journal of Control on Adaptive Sliding Mode Control and Observation.
An Adaptive Speed Control Approach for DC Shunt Motors
Energies
https://doi.org/10.3390/en9110961
Rubén Tapia Olvera 1 , Francisco Beltrán Carbajal 2 , Omar Aguilar Mejía 3 , Antonio Valderrabano González 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
3 Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrados
4 Universidad Panamericana, Facultad de Ingeniería

Keywords: DC shunt motors, adaptive speed control, model-free control, neural networks
Abstract: A B-spline neural networks-based adaptive control technique for angular speed reference trajectory tracking tasks with highly efficient performance for direct current shunt motors is proposed. A methodology for adaptive control and its proper training procedure are introduced. This algorithm sets the control signal without using a detailed mathematical model nor exact values of the parameters of the nonlinear dynamic system. The proposed robust adaptive tracking control scheme only requires measurements of the velocity output signal. Thus, real-time measurements or estimations of acceleration, current and disturbance signals are avoided. Experimental results confirm the efficient and robust performance of the proposed control approach for highly demanding motor operation conditions exposed to variable-speed reference trajectories and completely unknown load torque. Hence, laboratory experimental tests on a direct current shunt motor prove the viability of the proposed adaptive output feedback trajectory tracking control approach.
Modelado Matemático y Control PD de un Quadrotor
Difu100ci@ Revista en Ingeniería y Tecnología
http://editorial-uaie.uaz.edu.mx/index.php/difu100cia/article/view/113
Hugo Yáñez Badillo 1 , Rubén Tapia Olvera 2 , Francisco Beltrán Carbajal 3 , Omar Aguilar Mejía 4 , Irvin López García 3
1 Universidad Politécnica de Tulancingo, Departamento de Posgrado
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
4 Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrados

Keywords:
Abstract: Se presenta el modelado matemático y un enfoque de control proporcional derivativo (PD) de un helicóptero de cuatro rotores, el cual se conoce en la literatura con el nombre de Quadrotor. Se describe también algunas estrategias de control y aplicaciones actuales del Quadrotor desarrolladas por varios grupos de investigación. El modelo matemático de este sistema mecatrónico se desarrolla mediante la formulación de Newton-Euler. Posteriormente se plantea un controlador PD para seguimiento de trayectorias de referencia. Se incluyen algunos resultados de simulación computacional que muestran el desempeño adecuado del esquema de control.
Rotordynamic Optimization of Fixed Pad Journal Bearings Using Response Surface Design of Experiments
Journal of Engineering for Gas Turbines and Power
https://doi.org/10.1115/1.4034066
Leonardo Urbiola Soto 1 , Raymundo Santibañez Santoscoy 1 , Marcelo López Parra 1 , Alejandro Cuauhtémoc Ramírez Reivich 1 , Ricardo Yáñez Valdez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Design optimization
Abstract: The design process of journal bearings of turbomachines is complex and time-consuming due to the many geometric and physical variables involved. This paper reports on the design of experiments (DOE) and the response surface design of experiments (RSDOE) methods employed on the design of the drive-end and free-end three-lobe journal bearings supporting a centrifugal compressor rotor. The suitability of each technique is discussed. The bearing design variables employed are bearing slenderness ratio, radial clearance, preload, and lubricant inlet temperature. The rotordynamic response variables selected were the critical speed location, the vibrations at critical speed and operating speed for both bearings, and the threshold speed of instability. The use of a nonlinear (quadratic) RSDOE model is justified. An optimization approach combining an SRDOE and rotordynamic finite element modeling is presented. This method leads to arrive to a multivariate model for multi-objective optimization with very few computations. Identification of the dominant design variables and their effects on several response variables allows establishing engineering feasible solutions with focus on manufacturing versus operating conditions tradeoff.
Left ventricle segmentation in fetal echocardiography using a multi-texture active appearance model based on the steered Hermite transform
Computer Methods and Programs in Biomedicine
https://doi.org/10.1016/j.cmpb.2016.09.021
Lorena Vargas Quintero 1 , Boris Escalante Ramírez 1 , Lisbeth Camargo Marín 2 , Mario E. Guzmán Huerta 2 , Fernando Arámbula Cosío 3 , Héctor Borboa Olivares 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Nacional de Perinatología
3 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología

Keywords: Active appearance models, Fetal echocardiography, Hermite transform, Segmentation
Abstract: OBJECTIVE: Fetal echocardiographic analysis is essential for detecting cardiac defects at early gestational ages. Fetal cardiac function can be assessed by performing some measurements regarding the dimension and shape of the heart cavities. In this work we propose an automatic segmentation method applied to the analysis of the left ventricle in fetal echocardiography. METHODS: For segmentation of the left ventricle, we designed a novel multi-texture active appearance model (AAM) based on the Hermite transform (HT). Local orientation analysis is addressed by steering the coefficients obtained with the HT. The method basically consists of an AAM-based scheme which uses the steered HT to efficiently code texture patterns of the input image. A wider and detailed description of the image features can be obtained with this method. Compared with classic AAM methods, the segmentation performance is substantially improved with the proposed scheme. Since AAM-based approaches process local information, an automatic method is also proposed to initialize the multi-texture AAM. For this purpose, a database of pre-segmented images was built. Then, techniques such as thresholding, mathematical morphology and correlation are combined to identify the position and orientation of the left ventricle. Typical issues found in fetal cardiac ultrasound images such as different orientations and shape variations of the heart cavities can be easily handled with the designed method. RESULTS: Several images of fetal echocardiography were used to evaluate the proposed segmentation method. The algorithm performance was validated using different metrics. We used a database of 143 real images of fetal hearts acquired for different phases of the cardiac cycle. We obtained an average Dice coefficient of 0.8631 and a point-to-curve distance of 2.027 pixels. The proposed algorithm was also validated by comparing it with other segmentation methods. CONCLUSIONS: We have designed an automatic algorithm for left ventricle segmentation in fetal echocardiography. The reported results demonstrate that the proposed approach can achieve an efficient segmentation of the left ventricular cavity. Typical problems found in images of fetal echocardiography are satisfactorily handled with the proposed multi-texture AAM scheme.
Total replacement of recycled aggregate and treated wastewater: concrete recycling in extremis
Journal of Sustainable Architecture and Civil Engineering
https://doi.org/10.5755/j01.sace.15.2.15464
Mayanin Gisela Ramírez Tenjhay 1 , Alba Beatriz Vázquez González 1 , José Manuel Gómez Soberón 2 , Francisca Guadalupe Cabrera Covarrubias 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Politécnica de Cataluña, Escuela de Construcción de Edificaciones de Barcelona
3 Universidad Politécnica de Cataluña, Escuela de Ingeniería Civil

Keywords: recycled aggregates, recycled concrete, sustainable materials, treated wastewater
Abstract: Million tons of construction and demolition waste (CDW) are generated every year around the world, and most of them are not adequately disposed, generating significant pollution on water, soil and air. Additionally, the use of freshwater in industrial processes, such as the production of cement, concrete manufacturing and curing for newly-built structures; has damaged the health of our freshwater ecosystems, reducing their volume and hindering their natural cycle of renovation. Therefore, the incorporation of recycled aggregate (RA) and treated wastewater (TW) as substitutes for the usual aggregates (UA) and freshwater, could generate significant environmental benefits. In this research, a comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement percentage of UA for RA, is presented; and as an innovation the use TW. The results show that, regardless of the replacement percentage and use of treated wastewater, a concrete with RA and TW (recycled concrete in extremis, CRiE) had a satisfactory and acceptable or equivalent performance, not differing significantly from the performance of conventional concrete (CC), confirming that the use of RA for concrete building is feasible.
Time-Varying Gain Differentiator: A Mobile Hydraulic System Case Study
IEEE Transactions on Control Systems Technology
https://doi.org/10.1109/TCST.2015.2512880
Carlos Vázquez 1 , Stanislav Aranovskiy 2 , Leonid Freidovich 3 , Leonid Fridman Golredich 4
1 Umea University, Department of Applied Physics and Electronics
2 INRIA Lille - Nord Europe
3 Umea University, Robotics and Control Laboratory
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Time-Varying gain differentiator, mobile hydraulic system, second order sliding mode, high-gain oberver, on-line differentiator, velocity observer
Abstract: In mobile hydraulic systems, velocities are typically not measured. However, using their reliable estimates for feedback is known to allow designing better control laws. We are going to present a specialized technique to compute such estimates using measurements of positions and pressures in the chambers of hydraulic cylinders. With a rough estimate for an upper bound of the second derivative, computed online from pressures, the goal is to find the first derivative of the position signal in the presence of noise. We propose a differentiator with a continuous time-varying gain, constructed from pressure measurements, achieving chattering attenuation without compromising the performance of estimation. The gain is constructively tuned using analysis based on a time-varying Lyapunov function. In addition, the obtained ultimate bounds on differentiation errors provide a criterion for the enhancement of the precision of the proposed algorithm with a constructive design of its parameters. The experimental results over a forestry-standard mobile hydraulic crane confirm the advantages of the methodology.
A fast and effective method for static video summarization on compressed domain
IEEE Latin America Transactions
https://doi.org/10.1109/TLA.2016.7795828
Antonio Cedillo Hernández 1 , Manuel Cedillo Hernández 1 , Francisco Javier García Ugalde 2 , Mariko Nakano Miyatake 1 , Héctor Pérez Meana 1
1 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Compressed domain, Key-Frame Extraction, Video Summarization
Abstract: Current advances in information technologies have led to the creation of huge video databases. Efficient and effective video summarization methods are needed to quickly browse and locate required video content. In this paper, we present a fast and effective video summarization method that is implemented in the compressed domain. Our four-step proposed method relies on a simple yet powerful descriptor and a scene-detection method, to detect gradual and abrupt transitions with great precision. A saliency-based refinement strategy is used to avoid redundancy and represent video content with as few key-frames as possible. Several experiments were done to assess the proposed method's performance, concluding that it is superior to current solutions.
A visible watermarking with automated location technique for copyright protection of portrait images
IEICE Transactions on Information and Systems
https://doi.org/10.1587/transinf.2015EDP7412
Antonio Cedillo Hernández 1 , Manuel Cedillo Hernández 2 , Francisco Javier García Ugalde 1 , Mariko Nakano Miyatake 2 , Héctor Pérez Meana 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación

Keywords: visible watermarking, copyright protection, portrait images, human visual system
Abstract: A visible watermarking technique to provide copyright protection for portrait images is proposed in this paper. The proposal is focused on real-world applications where a portrait image is printed and illegitimately used for commercial purposes. It is well known that this is one of the most difficult challenges to prove ownership through current watermark techniques. We propose an original approach which avoids the deficiencies of typical watermarking methods in practical scenarios by introducing a smart process to automatically detect the most suitable region of the portrait image, where the visible watermark goes unnoticed to the naked eye of a viewer and is robust enough to remain visible when printed. The position of the watermark is determined by performing an analysis of the portrait image characteristics taking into account several conditions of their spatial information together with human visual system properties. Once the location is set, the watermark embedding process is performed adaptively by creating a contrast effect between the watermark and its background. Several experiments are performed to illustrate the proper functioning of the proposed watermark algorithm on portrait images with different characteristics, including dimensions, backgrounds, illumination and texture, with the conclusion that it can be applied in many practical situations.
Copyright Protection in Video Distribution Systems by Using a Fast and Robust Watermarking Scheme
Springer International Publishing Switzerland
https://doi.org/10.1007/978-3-319-42007-3_35
Antonio Cedillo Hernández 1 , Manuel Cedillo Hernández 2 , Francisco Javier García Ugalde 1 , Mariko Nakano Miyatake 2 , Héctor Pérez Meana 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación

Keywords: Video watermarking, Human Visual System, Video distribution systems
Abstract: In this paper we propose a watermarking scheme to ensure copyright protection in video distribution systems. This research is focused on provide a low computational cost solution that allows embedding a robust and imperceptible watermarking signal in the video content, such that the original video transmission rate will not be affected. Our proposal accomplishes this challenge by introducing a fast and effective method based on spatio-temporal Human Visual System properties that allow improving imperceptibility along video sequence and at the same time, enhancing robustness. Extensive experiments were performed to prove that the proposed algorithm satisfies quickness, invisibility and robustness against several real-world video processing issues. The proposed scheme has the advantages of robustness, simplicity and flexibility, allowing it to be considered a good solution in practical situations since it can be adapted to different video distribution systems.
Novel Online Tools for Automatic Generation of Pronouncing Dictionaries in Mexican Spanish for Speech Processing
International Journal of Signal Processing Systems
https://doi.org/10.12720/ijsps.4.1.51-54
Carlos Hernandez Mena 1 , Abel Herrera Camacho 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Mexican Spanish, Mexbet, pronouncing dictionary, phonetic alphabet
Abstract: A pronouncing dictionary is a very important tool in a speech processing system. In speech recognition, it helps to the training stage to create the Markov models for every phoneme of every word in the lexicon. In speech synthesis, it helps the system to produce the correct pronunciations of the words introduced by the user despite the orthographic representations of them. All of this implies that creation of pronouncing dictionaries depends on the language one has chosen, because different languages have different sets of phonemes and also different phonetic alphabets to represent them. In this paper we present a methodology of creation of pronouncing dictionaries in Mexican Spanish utilizing a set of novel online tools developed by the CIEMPIESS-UNAM Project. These tools are for free use and they produce pronouncing dictionaries in a particular phonetic alphabet called Mexbet.
A New Methodology for Tracking and Instantaneous Characterization of Voltage Variations
IEEE Transactions on Instrumentation and Measurement
https://doi.org/10.1109/TIM.2016.2540866
Martin Valtierra Rodriguez 1 , David Granados Lieberman 2 , José E. Torres Fernández 2 , Juan Ramón Rodríguez Rodríguez 3 , José Francisco Gómez Aguilar 4
1 Universidad Autónoma de Querétaro, Facultad de Ingeniería campus San Juan del Río.
2 Instituto Tecnológico Superior de Irapuato, Facultad de Ingeniería Electromecanica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Tecnológico Nacional de México

Keywords: Fuzzy logic, IEEE Standards, Monitoring, Voltage measurement, Transforms, Field programmable gate arrays, Target tracking
Abstract: Accurate and fast characterization of voltage variations helps to evaluate their severity on equipment and activate protections. In this paper, a methodology for tracking and characterization of voltage variations, sample to sample, is presented. It consists of a Hilbert transform to estimate the voltage of the signal's envelope, a fuzzy logic system to track down the type of voltage variation, and a rule-based method for the final identification and decision making according to IEEE Std 1159-2009. Unlike some techniques presented in the literature for tracking voltage variations such as the Kalman filter and adaptive linear network techniques, the proposed methodology requires neither a harmonic model nor an algorithm to adjust the model parameters, which in many cases increases the computational burden and time tracking. It is worth mentioning that the proposed classification stage does not need a training stage; therefore, its development is easier and its efficiency does not depend on a data training set. The performance of the proposed methodology is validated and tested using synthetic signals as well as real measurements of voltage variations. In addition, an implementation of our methodology into an field-programmable gate array based system is performed in an effort to offer a low-cost and portable system-on-a-chip solution for online and real-time monitoring of voltage variations.
The Proportional-Values Modulation (PVM), a technique forimproving efficiency and power density of bidirectional DABconvertersJuan
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2016.12.014
Juan Ramón Rodríguez Rodríguez 1 , Edgar Lenimirko Moreno Goytia 2 , Vicente Venegas Rebollar 3 , Luis E. Ugalde Caballero 4 , Adolfo Anaya Ruiz 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico de Morelia, División de Estudios de Posgrado e Investigación
3 Instituto Tecnológico de Morelia, Programa de Graduados e Investigación en Ingeniería Eléctrica (PGIIE)
4 Instituto Tecnológico de Morelia, Ingeniería Eléctrica

Keywords: DC??DC conversion, Modulation, Dual active bridge converter, Efficiency, Reactive power elimination
Abstract: This work introduces the Proportional-Values Modulation (PVM), an advanced technique for modulating DC??DC DAB converters. The relative advantages of this technique are: (i) Full elimination of reactive power throughout the bidirectional operating range of the DAB; (ii) reduction of the apparent power in the high-frequency transformer, HFT, while maintaining the harmonic distortion low, and (iii) the output capacitance is lower than the one obtained using Single-Phase-Shift Control (SPSC) and Dual-Phase-Shift Control (DPSC) methods, while the AC and DC current peaks are not incremented. This set of advantages increases the overall technical efficiency and power density flow of the converter. As additional characteristics of interest, the technique uses a single feedback PI loop and no complex control rules are implemented. Both features increase the computational efficiency of the PVM above other proposals.
Speed-sensorless control of SR motors based on GPI observers
Control Engineering Practice
https://doi.org/10.1016/j.conengprac.2015.10.010
Alejandra De La Guerra 1 , Marco Antonio Arteaga Pérez 1 , Alejandro Gutiérrez Giles 1 , Paul Rolando Maya Ortíz 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Switched reluctance motors, Speed control, Robust control, Disturbance rejection, Observers design
Abstract: This paper presents a robust speed-sensorless controller based on Generalized Proportional Integral (GPI) Observers for Switched Reluctance Motors. It compensates the unknown load torque while naturally estimates the output phase variables, making unnecessary to directly measure the angular velocity. An experimental comparison of the proposed controller with two other well-known similar schemes, carried out on a three phase 12/8 SR motor, shows the good performance of the proposed scheme.
Sistemas de información geográfica y cartografía geomorfológica aplicados al inventario de deslizamientos y cartografía de susceptibilidad en la cuenca del río El Estado, Pico de Orizaba, México
Investigaciones Geográficas
http://dx.doi.org/10.14350/rig.46503
José Fernando Aceves Quesada 1 , Gabriel Legorreta Paulín 1 , José Lugo Hubp 1 , Juan Umaña Romero 2 , Héctor Alfredo Legorreta Cuevas 2
1 Universidad Nacional Autónoma de México, Instituto de Geografía
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: SIG, cartografía geomorfológica, mapa de inventario de deslizamientos, mapa de susceptibilidad de deslizamientos, regresión múltiple logística, Volcán Pico de Orizaba
Abstract: Con el propósito de fortalecer el conocimiento y la prevención de los desastres por deslizamientos en este trabajo se desarrolla una metodología que integra la cartografía geomorfológica con la elaboración de mapas de susceptibilidad a deslizamientos usando los sistemas de información geográfica (SIG) y el método de regresión logística múltiple (RLM). En México se han realizado algunos trabajos aislados con los SIG para evaluar la estabilidad de laderas. Sin embargo, hasta ahora no se ha desarrollado ningún método práctico y estandarizado que integre los mapas geomorfológicos con los inventarios de deslizamientos utilizando los SIG. Este artículo muestra el análisis llevado a cabo para elaborar un inventario de deslizamientos multitemporal junto con la técnica de análisis y cartografía morfométrica de la cuenca del río El Estado. La cuenca del río El Estado, seleccionada como área de estudio, se localiza en la ladera sudoeste del volcán Citlaltepetl o Pico de Orizaba. Los factores geológicos y geomorfológicos en combinación con la alta precipitación estacional, el alto grado de intemperismo y las laderas escarpadas predisponen sus superficies a deslizamientos. Para evaluar la susceptibilidad por deslizamientos de tierras se elaboró un mapa de inventario de deslizamientos usando fotografías aéreas, a continuación se elaboró la cartografía geomorfométrica (altimétrico, pendientes y geomorfográfico) y se realizó trabajo de campo. Con esta información se modeló la susceptibilidad por deslizamientos usando regresión logística múltiple (RLM) dentro de la plataforma de un SIG y se obtuvo el mapa de susceptibilidad por deslizamientos.
Propagation of linear long water waves on a cycloidal breakwater
Journal of Engineering Mathematics
https://doi-org.pbidi.unam.mx:2443/10.1007/s10665-015-9841-7
Ayrton Alfonso Medina Rodríguez 1 , Eric Gustavo Bautista Godínez 1 , Federico Méndez Lavielle 2 , Oscar Eladio Bautista Godínez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Approximate analytical solution, Linear long water waves, Matrix method, Reflection/transmission of water waves, Submerged cycloidal breakwater, Taylor polynomials
Abstract: In this work, we carried out a theoretical analysis of the reflection, transmission and surface deformation of long linear water waves, propagating on a submerged breakwater whose cross-section obeys a cycloidal geometric transition. We use the well-known one-dimensional governing equations for the propagation of linear shallow-water waves, which are presented in their dimensionless version. Considering harmonic wave propagation, the governing equations can be reduced to a dimensionless second-order differential equation with variable coefficients for predicting the elevation of water waves. This equation is solved using a matrix method based on Taylor polynomials. In particular, we evaluate the reflection and transmission coefficients for three breakwaters, namely, cycloidal, semi-cycloidal and quarter-cycloidal. The first case exhibits the smallest transmission coefficient. The present mathematical model is compared with a simple numerical solution and with another analytical solution expressed in terms of the Legendre functions. The present mathematical model can be used as a practical reference for design of the geometrical configurations of submerged cycloidal breakwaters under shallow-flow conditions.
Unsteady mixed convection heat transfer from two confined isothermal circular cylinders in tandem: Buoyancy and tube spacing effects
International Journal of Heat and Fluid Flow
https://doi.org/10.1016/j.ijheatfluidflow.2016.04.001
Erick Salcedo 1 , Juan Carlos Cajas García 2 , César Treviño 3 , Lorenzo Martínez Suástegui 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Barcelona Supercomputing Center
3 Universidad Nacional Autónoma de México, Facultad de Ciencias
4 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Mixed convection, Tandem cylinders, Tube spacing, Blockage ratio, Interference effects
Abstract: In this work, two-dimensional numerical simulations are carried out to investigate the unsteady mixed convection heat transfer in a laminar cross-flow from two equal-sized isothermal in-line cylinders confined inside a vertical channel. The governing equations are solved using the vorticity-stream function formulation of the incompressible Navier??Stokes and energy equations using the control-volume method on a non-uniform orthogonal Cartesian grid. The numerical scheme is validated for the standard case of a symmetrically confined isothermal circular cylinder in a plane channel. Calculations are performed for flow conditions with Reynolds number of ReD = 200, a fixed value of the Prandtl number of Pr = 0.744, values of the buoyancy parameter (Richardson number) in the range -1
Correlation of high-hydrophobic sol-gel coatings with electrochemical and morphological measurements deposited on AA2024
Surface and Interface Analysis
https://doi.org/10.1002/sia.5976
Miguel Ángel Hernández Gallegos 1 , O. Inti Ramos 2 , J. Guadalupe Bañuelos 3 , E. Bucio E. 4 , Alba Covelo Villar 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
4 Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares

Keywords: EIS, sol?gel, hydrophobicity, aluminum 2024?T3, rugosity
Abstract: The present paper is focused on studying the behavior of a modified silica sol?gel coating with a high contact angle deposited on AA2024?T3. The sol?gel coating was prepared by the copolymerization of 3?Glycydoxypropyltrimethoxysilane (GPTMS) and tetra?n?propoxyzirconium (TPOZ). During the sol?gel synthetization procedure, commercial fluoro?emulsion solutions (CH and SA) were incorporated at different volume percentages. Prior to the sol?gel deposition by the spin?coating method, the aluminum substrate was ground with commercial sandpaper grit?220. Conventional measurements of the water?drop contact angle give values from 82.6° up to 118.9°. This indicates that the fluropolymer solutions modified the sol?gel's composition. This modification was evidenced by Fourier transform infrared analysis. The rugosity and morphology characteristics were measured by using atomic force microscopy and mechanical profilometry measurements. As the hydrophobic behavior increased, an increment of the rugosity profile was obtained. electrochemical impedance spectroscopy showed the highest protective properties of the sol?gel for the high hidrophobic coating. By means of electrochemical noise measurements, the rescaled range analysis was calculated for all modified sol?gel coatings. These results show that the higher the hydrophobic condition, the lower the fractal dimension. Thus, there is less corrosion activity. A hydrophobic surface modifies the macro?roughness, micro?roughness, and nano?roughness by smoothening the roughness profile.
Interpretación del registro geofísico del pozo profundo San Lorenzo Tezonco y su correlación litológica en la cuenca de México
Revista Mexicana de Ciencias Geológicas
https://doi.org/10.22201/cgeo.20072902e.2016.2.497
José L. Lezama Campos 1 , Eric Morales Casique 1 , Ricardo Castrejón Pineda 2 , José L. Arce 1 , Oscar A. Escolero 1
1 Universidad Nacional Autónoma de México, Instituto de Geología
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: San Lorenzo Tezonco deep well, geophysical well log, volcanic stratigraphy, basin of Mexico
Abstract: We describe the results obtained from the analysis of the geophysical well log conducted at the San Lorenzo Tezonco (SLT) well, which is located in the eastern part of Mexico City and has 2,008 m in depth. The geophysical well log was conducted in three stages and consisted of temperature, electrical resistivity, natural potential and gamma radiation, although the gamma radiation and natural potential logs malfunctioned during the last stage. The analysis presented here is based mainly on the electrical resistivity and gamma logs; the interpretation is based on channel (cutting) samples and petrologic and stratigraphic descriptions of the SLT well previously published. By analyzing the well log data and correlating them with the lithology reported for nearby shallow wells it was possible to complete the stratigraphy between 120 m and 500 m, which was absent in previous reports due to the lack of channel cuttings. The results show that the geologic materials in the SLT well are considerably more heterogeneous and have differing thicknesses than those previously reported. Among the zones of hydrogeological interest, an aquitard of volcanic origin, with relatively low clay content, is inferred between 750 and 880 m depth from the well log. In addition, the analysis allowed identifying potential water-productive strata. For future exploratory deep wells in the Basin of Mexico, it is suggested to include additional geophysical logs (density and sonic) and to obtain cores, which would allow a quantitative interpretation of petrophysical properties of the subsurface.
Effect of a viscosity reducer in a liquid-liquid flow: II unsteady state annular model in a pipeline
Revista Mexicana de Ingeniería Química
http://rmiq.org/iqfvp/Vol15No3.html
E. J. Suárez 1 , Francisco Javier Solorio Ordaz 2 , A. E. Chávez 3 , E. Izquierdo 3 , A. Rodríguez 3 , A. Palacio 3
1 Centro de Investigación Aplicada y Tecnológica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3

Keywords: two-phase flow, non-steady profile, extra heavy crude, high viscosity
Abstract: The study of extra heavy crude oil flow has increased in recent years, due to the challenges relating to higher viscosity that limits the installed capacity of pipelines and the pumping infrastructure used. This has required the development and implementation of new technologies and chemical formulations to enhance the transport of heavy oil. When flow improvers are injected in a crude stream, it generally does not mix due to its different density and viscosity properties, and the laminar flow regime in the pipe. However, depending on the characteristics of the jet (momentum and turbulence), a mixing might take effect downstream, or a liquid-liquid stratified flow may occur in the fully developed region. Although this behavior can affect the corresponding pressure drop, the transition that occurs from the injection point to the fully developed region has been little studied. Based on conservation of momentum, a mathematical model has been developed to describe the temporal behavior of the velocity profile, where there is no mixing between the oil and the improver, i.e. the fluids are considered immiscible. The model solution shows that the injection into a point very near the tube wall is the best option to reduce pressure drop.
Simulación computacional de tejido óseo como apoyo al sistema de salud cubano
Revista Cubana de Investigaciones Biomédicas
https://www.medigraphic.com/cgi-bin/new/resumen.cgi?IDARTICULO=70496
Yosbel Angel Cisneros Hidalgo 1 , Raide Alfonso González Carbonell 1 , Armando Ortiz Prado 2 , Víctor Hugo Jacobo Armendáriz 2 , Miriam Venerada Hidalgo González 1
1 Universidad de Camagüey "Ignacio Agramonte Loynaz"""
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: simulación computacional, modelo, torsión tibial, salud
Abstract: Introducción: con el desarrollo de las nuevas tecnologías y la simulación computacional se abren las puertas a soluciones de problemas complejos en el campo de la medicina. Objetivo: realizar una valoración sobre la importancia de la simulación computacional como apoyo al sistema de salud en Cuba. Métodos: para el estudio fue necesario realizar una búsqueda de la situación actual que presenta Cuba en temas de bioingeniería, la investigación se centró en los centros hospitalarios de la provincia de Camagüey en los cuales se entrevistaron a doctores y personal técnico relacionados con la ortopedia. Resultados: con las condiciones actuales y el equipamiento instalado en los centros hospitalarios cubanos es factible aplicar las técnicas de modelación computacional de tejidos y órganos para una medicina cada vez menos invasiva. Conclusiones: es posible emplear la simulación computacional de tejidos y órganos como apoyo en el seguimiento, pronóstico y diagnóstico de enfermedades. Existen aislados intentos de vinculación entre instituciones hospitalarias y centros de investigación universitarios.
Advanced Control of Complex Dynamical Systems with Applications
Mathematical Problems in Engineering
https://doi.org/10.1155/2016/4389457
Xing Gang Ya 1 , Sarah Spurgeon 1 , Qingling Zhang 2 , Leonid Fridman Golredich 3
1 University of Kent, School of Engineering and Digital Arts
2 Northeastern University, Institute of Systems Science
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: There are many practical systems which can be modelled by dynamical equations. Increasing requirements on system performance mean that within control system analysis and design it is necessary to deal with the increasingly complex dynamical systems that are used to model reality. The complexity stems from nonlinearity, uncertainty, time delay, system singularity, stochastic effects, the presence of interconnections, and so forth. Advances in both technology and control theory have provided the potential to investigate complex dynamical systems. Study on complex systems is becoming increasingly important and this has provided renewed impetus for the development of novel techniques and skills for complex control systems. This provides the motivation for this special issue.
A Generalized Frame of Reference for the Incorporation of Multi-Terminal VSC-HVDC Systems in Power Flow Solutions
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2016.03.009
Enrique Acha Daza 1 , Luis Miguel Castro González 2
1 Tampere University of Applied Sciences, Faculty of Information Technology and Communication Sciences - Electrical Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: MT-HVDC systems, Newton-Raphson method, Power flows, VSC-HVDC modeling
Abstract: This paper introduces a new and general frame-of-reference for true unified, iterative solutions of AC/DC power flows using the Newton-Raphson method. The emphasis is placed on the so-called multi-terminal VSC-HVDC systems. This frame-of-reference accommodates quite naturally any number of AC/DC sub-networks generated by an arbitrary number of VSC converters. Besides, each AC sub-network may contain any number of FACTS devices. The modeling approach adopted for the multi-terminal VSC-HVDC systems is incremental in nature. An AC system of arbitrary configuration is connected to the high-voltage side of the VSC's LTC transformer. In turn, the DC side of each pairing VSC is linked to a DC system of arbitrary configuration. The new model represents a paradigm shift in the way the fundamental frequency, positive sequence modeling of VSC-HVDC links are modeled, where the VSCs are not treated as idealized, controllable voltage sources but rather as compound transformer devices with which key control properties of the PWM-based converters are linked. In contrast to other contemporary approaches, the power flow iterative solutions carried out using the reference frame put forward in this paper exhibits a true quadratic convergence characteristic ?? in most credible cases, convergence to a tight power mismatch tolerance of e??12 would be achieved in five or less iterations.