• Selección de atributos considerando inter-dependencias

      Mejía Lavalle, Manuel; MANUEL MEJIA LAVALLE;55801 (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2007-03-01)
      Las bases de datos están creciendo a un ritmo acelerado, propiciado por diversos avances tecnológicos. Esto crea un problema para los algoritmos tradicionales de descubrimiento de conocimiento, los cuales no fueron diseñados para escalar con el tamaño de atributos e instancias, redundando en tiempos excesivos de procesamiento y/o agotamiento de la memoria principal, aÚn en computadoras de gran tamaño. Una estrategia para solucionar lo anterior es la Selección de Atributos, que busca eliminar los atributos irrelevantes y redundantes de una base de datos. Idealmente, la Selección de Atributos reduce el tiempo y la cantidad de memoria necesaria para el procesamiento de los datos. Además es capaz de mantener, e incluso mejorar, la exactitud predictiva del algoritmo de inducción y produce modelos de conocimiento más pequeños que son más fáciles de entender por el usuario final. Aunque existe una gran variedad de métodos para Selección de Atributos, muchos de ellos asumen que los atributos son independientes entre ellos, por lo que excluyen subconjuntos de atributos que resultan relevantes sólo cuando se consideran juntos. En esta tesis se investigan, proponen y experimenta con algoritmos eficientes y eficaces de Selección de Atributos que consideran las inter-dependencias entre los atributos y la clase discreta, empleando una nueva función heurística basada en la entropía n-dimensional. También se analiza y avanza en el caso cuando los atributos son continuos y la clase discreta, usando una nueva función heurística basada en la Ganancia de Información y el determinante de la matriz de covarianzas de los atributos. En los experimentos realizados, los algoritmos propuestos muestran, en la mayoría de los casos, igualar o superar a métodos tradicionales de Selección de Atributos en cuanto a reducción del nÚmero de atributos y exactitud predictiva, con un tiempo de procesamiento competitivo. En esta tesis también se analizan y discuten variaciones de los algoritmos propuestos así como sus limitaciones, y se enfatizan las direcciones futuras de investigación.
    • Self-Assembly behavior of amphiphilic janus dendrimers in water: a combined experimental and coarse-grained molecular dynamics simulation approach

      Valencia Gallegos, Jesús Ángel; Videa Vargas, Marcelo Fernando; Elizondo García, Mariana Estefanía; Gutiérrez Uribe, Janet Alejandra; González Nilo, Fernando Danilo; Cortéz Ramírez, Jorge (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2018-05-14)
      Amphiphilic Janus dendrimers (JDs) are repetitively branched molecules with hydrophilic and hydrophobic components that self-assemble in water to form a variety of morphologies, including vesicles analogous to liposomes with potential pharmaceutical and medical application. To date, the self-assembly of JDs has not been fully investigated thus it is important to gain insight into its mechanism and dependence on JDs’ molecular structure. In this study, a series of amphiphilic JDs with variations in their core and branching pattern was synthesized and its aggregation behavior in water was evaluated using experimental and computational methods. JDs were obtained from 2,2-bis(hydroxymethyl)propionic acid, myristic acid and different glycols. Dispersions of JDs in water were carried out using the thin-film hydration, solvent injection methods and by microfluidics, using double emulsion drops with ultrathin shells as templates. Furthermore, a coarse-grained molecular dynamics (CG-MD) simulation was performed to study the mechanism of JDs aggregation. The resulting assemblies were characterized by optical microscopy, dynamic light scattering, confocal microscopy, and atomic force microscopy. The obtaining of assemblies in water with no interdigitated bilayers was confirmed by the experimental characterization and CG-MD simulation for one of the dendrimers. Assemblies with dendrimersome characteristics were obtained using the solvent injection method. Also, monodisperse nanometric assemblies were obtained by this method. The use of microfluidics enables the production of giant dendrimersomes from highly hydrophobic JDs, even when the dendrimers did not form vesicles using the thin-film hydration method. The results of this study establish a relationship between the molecular structure of the JDs and the properties of its aggregates in water. These results could be relevant for the design of novel JDs with tailored assemblies suitable for drug delivery systems. In addition, this study offers an approach to produce dendrimersomes in a more controlled way.
    • Sistemas Exaptivos: Retención y Reutilización de Conocimiento en Algoritmos Evolutivos

      Torres Treviño, Luis M. (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2004-01-05)
      El objetivo de la tesis es desarrollar un sistema con la capacidad de retener y reutilizar soluciones para resolver problemas dinámicos. Se considera que existen dos tipos de problemas dinámicos, los primeros se relacionan con la optimización de funciones dinámicas y los segundos se relacionan con el aprendizaje en un medio ambiente dinámico. Las soluciones de los problemas dinámicos son importantes porque es el comÚn de los problemas reales. La tesis se inspira en la exaptación que es el proceso evolutivo en el cual una estructura adaptada para una función particular se utiliza para lograr otra función generalmente diferente a la que se adaptó. Para implantar el proceso evolutivo de la exaptación se analizan algunos algoritmos evolutivos. También se analizan los mecanismos de aprendizaje que utilizan algoritmos evolutivos ya que se quiere involucrar a la exaptación en los mecanismos de aprendizaje. La exaptación tiene una relación con el aprendizaje por analogía; por lo cual también puede brindar una guía para la implantación de un sistema con capacidades exaptivas. La exaptación se divide en dos procedimientos, el primero es la reutilización de soluciones, el segundo es la retención. Para el primer procedimiento se analizan técnicas para modificar soluciones e insertarlas en la población inicial de un algoritmo genético u otro algoritmo evolutivo. Para el segundo procedimiento se analizan algunos algoritmos evolutivos que mantienen la diversidad en la población y se utilizan mecanismos de memoria junto con algunas técnicas de reutilización para formar sistemas evolutivos capaces de resolver problemas dinámicos. En la optimización de funciones dinámicas se probaron dos algoritmos con capacidades exaptivas y se comparó el desempeño con otro algoritmo especializado en resolver estos problemas. Se demuestra que los algoritmos propuestos son competitivos. En el aprendizaje en un medio ambiente dinámico, se utilizó una red neuronal sencilla con propiedades exaptivas que le permite aprender varias funciones en una sola estructura. Finalmente se propone el uso de un agente inteligente con capacidades exaptivas en la reprogramación de tareas para demostrar que los procedimientos exaptivos propuestos le brindan alguna ventaja al agente comparado con otro agente que no tiene capacidades exaptivas.
    • Sliding mode control for doubly fed induction machine

      Pedro Ponce Cruz; Arturo Molina Gutiérrez; Villanueva Rosas, Iván Salvador; José Antonio Rosales Martínez; Juan Carlos Ramírez Martínez; Carlos Ernesto Ugalde Loo (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2017-12-01)
      The objective of this thesis is to provide robust control methods for Doubly Fed Induction Generator (DFIG) mainly used for wind energy conversion systems (WECS). The controller deals with the power electronic stage needed to control the electric machine. Due to the high sensibility of this machine against disturbances the systems requires an accurate controller that allows to follow the stator power regulation despite the presence of disturbances.       DFIG-based WECS are highly sensible to stator voltage perturbations because the stator is directly connected to the electric grid. The offered controller can regulate torque and reactive power even during low depth voltage dips by injecting negative sequence current without the necessity of sequence components separation of the rotor current.                  The proposed control system is based on Sliding-Mode Control (SMC),  offering a fast-dynamic response and providing insensitivity to matched and bounded disturbance/uncertainties. The naturally discontinuous control signals of SMC can be used for direct switching of power electronic devices avoiding modulation and making the control system simple and robust. Furthermore, the controller does not depend on electric machine's parameters and it is decoupled by means of reference frame orientation.                  The switching frequency is analyzed using a frequency-domain method known as Tsypkin's locus, therefore it is possible to calculate a hysteresis width which will maintain the switching frequency inside safe operational range preventing to exceed the maximum switching frequency of semiconductor devices.                  The dynamic response of the control system under balanced and unbalanced voltage faults is enhanced by the application of demagnetizing current for fast natural flux clearance. The demagnetizing current is supplied using the original controller by modifying the torque and reactive power references.                     The operation of the controller and the ideas presented in this thesis have been verified through simulations made in National Instruments\textsuperscript LabVIEW and Matlab Simulink.
    • Solución Numérica de Problemas de Mecánica de Sólidos para Cuerpos con Grietas y/o Inclusiones

      Romero Medina, Víctor M. (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2009-01-15)
      El trabajo de investigación esta? enfocado en la aplicación de un me?todo nume?rico novedoso, denominado Me?todo de Puntos de Frontera, a la solución de las ecuaciones integrales en la frontera que se presentan en el estudio de meca?nica de cuerpos deformables, lo que permite reducir en una dimensión el ana?lisis en cuestión. Principalmente lo aplicamos a la solución de los siguientes problemas: 1. El segundo problema de elasticidad esta?tico de cuerpos homoge?neos en dos dimensiones, 2. El segundo problema de elasticidad esta?tico de cuerpos homoge?neos con grieta en dos dimensiones, 3. El segundo problema de plasticidad esta?tico de cuerpos homoge?neos en dos dimensiones, y 4. El segundo problema de elasticidad dina?mico de cuerpos homoge?neos con grieta en dos dimensiones. En el me?todo se utilizan funciones de aproximación tipo Gauss, lo que representa una gran ventaja de este modelo, ya que no se requiere discretizar la frontera en pequen?os elementos como en el BEM, sino que nos permite definir una cantidad finita de nodos o puntos sobre la frontera de los que sólo se requiere conocer caracteri?sticas geome?tricas tales como sus coordenadas y la orientación de vectores unitarios normales a la frontera en dichos puntos. Esto nos lleva a definir los componentes de la matriz de coeicientes mediante el ca?lculo anali?tico de integrales estandar cuyos valores se pueden guardar fa?cilmente en la memoria de la computadora para ser utilizados posteriormente en el ca?lculo de esfuerzos en el interior del dominio de solución, alcanzando una gran precisión. Los resultados obtenidos para los diferentes problemas son comparados con soluciones exactas existentes en los casos (1), (2) y (4), con resultados experimentales, como en el caso del factor de intensidad de esfuerzos del problema (2), y con modelos nume?ricos de elementos finitos en el caso del problema (3), mostrando gran precisión en la solución.
    • SQL2X QUERY : una herramienta para transformar expresiones de SQL a expresiones XQUERY para consultar repositorios de datos XML

      Francisco Javier Cartujano Escobar; FRANCISCO JAVIER CARTUJANO ESCOBAR (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2002)
    • Studies on CIS thin Films Deposited by R. F. Sputtering and CdS Nanoparticles Deposited by Microwave Assisted CBD for Photovoltaic Aplications

      Sampedro Soberanis, Rodrigo C. (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2009-12-01)
    • Suboptimal structures of channel encoding for fade mitigation in satellite communications

      David, Villena Rivera; DAVID, VILLENA RIVERA (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2015)
    • Tailored optical fields and their applications in quantum information processing

      Hernández Aranda, Raúl Ignacio; Korand, Thomas; Pérez García, Benjamín de Jesús; López Mago, Dorilián; Rodríguez Mesagosa, Rodolfo; Gutiérrez Vega, Julio César (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2018-05-15)
      A set of experimental techniques to digitally shape an optical beam are presented. In particular, we show how to digitally study the interference phenomena in different geometries and observables. We also present a novel way of generating arbitrary vector beams and controlling the spatial coherence of a classical beam using Spatial Light Modulators. These type of manipulations are further employed to control and experimentally implement quantum algorithms, more precisely the Deutsch, Deutsch-Jozsa and Grover`s search algorithms.
    • Thermo-hydraulic performance modeling of thermal energy systems using parabolic trough solar collectors

      Tagle Salazar, Pablo Daniel
      Solar energy is one of the most important emerging renewable energy resources. Parabolic trough solar collectors are one of the most used technologies for solar concentrating applications. The main purpose of this research is to develop a mathematical model for predicting thermodynamics and hydraulics of solar-to-heat conversion of thermal systems using parabolic trough collectors. Thermal model is based on energy balance of a one-dimensional steady-state heat transfer thermal resistance circuit. The receiver and its surroundings are considered as the control volume of the analysis. Heat transfer coefficients are obtained using experimental correlations found in the literature. The model considers single-phase and two-phase flow with phase-change effects, where pressure drop is solved simultaneously with thermal energy balance. The input data corresponds to optics properties, design of collector, weather data, and basic hydraulic parameters (for series or parallel configurations). Parabolic trough collectors with Al2O3/water nanofluid is also considered as a case of study. Computational simulations are carried out using Engineering Equation Solver (EES), a software developed to solve complex systems of non-linear equations. This software was selected due to its simplicity in programing systems of non-linear equations and the available database of thermophysical properties of number of substances, including water and steam. Experimental data is used to validate the model, comparing with simulation results. Simulations are realized using same ambient and inlet operational conditions as described in test results. Sources of experimental data are test results of four collectors (for efficiency curves case), a M.Sc. Thesis previously presented (for nanofluid case), and from data provided by Plataforma Solar de Almeria (for direct steam generation case). Results show a good agreement between simulations and experiments. Thermal parameters (such as thermal efficiency and temperatures) are predicted with high accuracy. There was obtained a global absolute error of around 1.5 °C for temperatures and 2% in thermal efficiency. Comparison of temperature and pressure profiles using simulation results and experimental data of a direct steam generation system in once-trough mode show that the model can predict phase-change phenomena with high accuracy. Although, the model fails in predicting pressure drop with high steam quality two-phase flow.
    • Towards a Secure Evaluation Environment For eLearning

      Marcus Martínez, Alejandro E. (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2008-01-05)
      This dissertation has the main objective of contributing to the definition of a Agent- based Reference Architecture for a Secure Examination environment in Internet-based Distance Learning. The main hypothesis was that it is possible to define this reference architecture with such a level of confidence as that of a Traditional Examination, where that confidence is measured as the capacity of confront potential cheating methods from foreseeable scenarios that allows the characterization of security dimensions to deal with the possible attack methods. In order to validate the security of such an environment, it was needed to enhance the traditional scenario technique for evaluating a software architecture: Current scenarios on the Software Engineering methodologies are more related to comply with software requirements of mature software domains, rather than with the underlying real world actions that generates them. In addition to this, there are no well-specified guides for de- riving security metrics in an architectural level beyond requirements compliance. Thus, this dissertation presents both a set of hierarchized metrics for calculating Security in eAssessment derived from the components responsabilities in such an environment and a evaluation methodology for relating and deriving those metrics. Those metrics are relevant to both technological and non-technological stakeholders, as they address both the domain analyzed and the architectural components responsabilities. As the Secure eAssessment field is not a matured and well-established software domain, the needed artifacts for validating solutions were not found: There were no referential software architectures that could be used for measuring the completeness and adequacy of a solution, neither a reference model to base on, nor even an structured abstraction of the underlying process. So, in this dissertation was needed to develop these artifacts, starting with a three-phase stage Secure eAssessment Process, that was derived onto a Reference Model and a further Reference Architecture based on a Client-Server Archi- tectural Style. From the traditional requirements compliance analysis, a Quick Security Checklist was also developed. The Reference Architecture presented is validated and compared against four current solutions on the field, that shows it addresses the educational cheating domain with un- especific details, as expectable for a non-matured domain, with better overall security that the solutions evaluated. A proof-of-concept prototyping experiment for a Software Monitoring Agent is also presented. The conclusions of this dissertation are that the contributions presented are significant for the development and maturement of the field. Future work relates to the need of generate implementations for software architectures that provide specific algorithmical details and further integration within existing eLearning platforms.
    • Tunneling and electromagnetic scattering in the open elliptic quantum billiard

      García Gracia, José H. (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2012-01-05)
      The study of open quantum billiards has gained popularity in the last decades, including dif? ferent common and uncommon geometries such as the circular and stadium billiards. We present an extensive analysis of the elliptic quantum billiard with hyperbolic channels. First we concentrate on quantum tunneling through an elliptic resonator-like structure, and we analyze three different variations of the system: the first configuration has horizontal channels, then we study the system with vertical leads, and finally we displace both channels by the same angle to gain a more general perspective. Next we study the vectorial scattering caused by the system for an incident TE polarized electric field. We analyze the same three physical configurations of the billiard, and the response of the Stokes polarization parameters to changes in the geometry of the system. We found that the quantum tunneling is very sensitive to changes in the parameters of the system, and we observed a standing-wave phenomenon inside the cavity of the billiard. Furthermore, we saw that the electromagnetic scattering of a vectorial field behaves smoothly when we change the geometry of the system, and no cir? culating polarization vortices were induced by the scattering for linearly polarized incident fields.
    • Un algoritmo genético para resolver el problema de asignar y secuenciar entregas con restricción de ventanas de tiempo

      José Rodolfo Torres Matus; JOSÉ RODOLFO TORRES MATUS (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2005)
    • Urban radio propagation for vehicular environments, a spatial vehicular traffic density channel characterization

      Granda Gutiérrez, Fausto Lenin
      Vehicular Ad Hoc Networks (VANETs) are envisaged to be a critical building block of Smart Cities and Intelligent Transportation System (ITS). Although there is a significant research effort in V2X (Vehicle-to-Infrastructure or Vehicle-to-Vehicle) radio channel characterization, the use of a deterministic approach as a complement of theoretical and empirical models is required to understand more accurately the propagation phenomena in urban environments. In this work, three computational tools were integrated to simulate the effects of the Vehicular Traffic Density (VTD) in the Urban Radio Propagation Channel (URPC) at 5.9Ghz: a 3D Ray-Launching (3D-RL), a detailed geographic database and a microscopic traffic simulator. Considerations as distance segmentation and spatial position from the transmitter were taken into account for accuracy and consistency in the subsequent analysis. Large-scale, small-scale, multipath metrics and coverage analysis is complemented with statistical characterization to explain the influence of different VTD levels in the URPC. Large-scale and small-scale results show the impact that factors such as relative Transmitter-Receiver (TX-RX) position, distance, link frequency, obstacles geometry, obstacles dielectric properties, and vehicle speed, have in the V2X propagation channel where parameters such as path loss exponent, amplitude of fading, and distribution shape factor cannot be assumed constant given the non-stationary nature of the vehicular communications channel. Otherwise, statistical characterization shows that Lognormal, and Weibull distributions can describe the fading RSS behavior for the VTD tested levels. The influence of the VTD in more significant in V2V and I2V links where. higher RSS values are related with the high VDT level, mainly in the vicinity of the TX, while there are not clear tendency or significant change in the RSS for V2X in remote areas from TX. These results are useful for radio-planning Wireless Sensor Networks (WSNs) designers and deployment of urban Road Side Units (RSUs)
    • WebMC : a model checker for the Web

      Victor Ferman; VICTOR FERMAN (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2016)
    • A Wrapper Component-Based Methodology for Integrating Distributed Robotics Systems

      Guedea Elizalde, Federico (Instituto Tecnológico y de Estudios Superiores de Monterrey, 2008-01-05)
      Building an intelligent robot system has been an extensive research area. There are many advances in components needed to construct a robotic system, such as vision systems, sensory systems, and planning systems among others. Integration of these components represents a big challenge for robot designers, because each component comes from different vendors and they run with different interfaces or under different operating systems. This will be even more difficult if the overall system development has to deal with environmental uncertainties or changing conditions. In these cases, new tools and equipments are necessary to adapt the initial configuration to the new changing requirements. Each added component increases the complexity of integration due to the interconnection required with the previous components. This thesis research presents a novel approach to solve the integration problem using the concepts of distributed framework and distributed computing systems. We named this methodology DWC (Divide-Wrap-Connect). This methodology is based on the mechanisms used by standard middleware software to provide transparency and porta- bility among different operating systems and languages. The idea is to define software modules named Wrapper Components, which are object-oriented modules that create an abstract interface for a specific class of hardware or software components. These modules are the components of a bigger system. Basic steps in this methodology are: a) Divide, b) Wrap and c) Connect. The creation of Wrapper Components is the core activity of the second step (b) but its design is af- fected by the first and third step of this methodology. We provide some basic definitions in order to clarify the scope of different design alternatives. Furthermore, we present how using standard mechanisms from distributed computing such as Event services and Naming services, the third step (c) is improved. We tested our approach by solving an experimental classical AI problem, block-world problem. The intelligent functions are object recognition, environment recognition, planning, tracking capabilities, tasks control and robot arm control. These functions were developed into several components and a coordinator module. This coordinator modules interacts with the user and the other components in order to solve the block- world problem. The construction of the system was done in an incremental way showing the benefits of this methodology.