Veintiún competencias laborales que desarrolla el trabajador social en la práctica escolar comunitaria UNAM

Este artículo enuncia los hallazgos encontrados en los 126 procesos de prácticas comunitarias realizadas durante el periodo 2007-2010, y que muestran la metodología utilizada con mayor frecuencia por los estudiantes de la licenciatura en Trabajo Social de la Universidad Nacional Autónoma de México (UNAM); se trata de una investigación documental cuantitativa, no experimental, de corte longitudinal y a nivel descriptivo que ofrece las competencias laborales que adquiere el estudiante. Se recolectó la información a través de la técnica de censo por medio de una cédula de información; como resultado presenta un modelo de competencias para el futuro trabajador social, el cual describe las capacidades que enfrenta este profesionista en los distintos tipos de comunidad en el Distrito Federal (DF) y el Estado de México. Esta indagación fue posible realizar gracias al trabajo colegiado de la Universidad Autónoma de Sinaloa (UAS), Universidad de Guadalajara (UdeG) y la Escuela Nacional de Trabajo Social (ENTS) de la UNAM en el marco de XVII Verano de la Investigación Científica y Tecnológica del Pacífico del Programa Delfín de la Academia Mexicana de Ciencias, cuyo hallazgo son las 21 competencias laborales que adquiere un alumno de la licenciatura de Trabajo Social en el ejercicio de la práctica escolar

Hybrid Wiener-Hammerstein Structure for Grey-Box Modeling of DC-DC Converters

In this work a generic hybrid model for dc-dc converters is proposed. The protections and remote control functions are managed by the logic system (event driven behaviour) and the power stage and control is modelled by a Wiener-Hammerstein structure. The model is oriented to be parameterized based on the information provided by manufacturers in their datasheet and it is able to predict power consumption, efficiency, system stability and large signal behaviour including inrush current, protections, start-up and remote on-off control

UNA MIRADA A LA RELACIÓN UNIVERSIDAD-GOBIERNO DESDE EL ENFOQUE RELACIONAL PARTICIPATIVO DE LA DIRECCIÓN ESTRATÉGICA

La teoría estratégica ha evolucionado a través de varios enfoques, marcando líneas de investigación disímiles. Entre ellos, el enfoque relacional–participativo, sitúa el énfasis en transformar y hacer mejor la organización desde la filosofía de la cooperación, por lo que cualquier decisión hacia afuera o hacia adentro de la organización debe ponderar en todo momento la dimensión humana de la misma, lo que sustenta su elección por los autores del presente artículo, orientado a fundamentar la relación universidad-gobierno desde dicho enfoque. El estudio de la relación universidad-gobierno y de las interinfluencias que se generan entre ambos, desde el perfeccionamiento de los procesos de dirección que respaldan esta relación, implica redimensionar los procesos socio-psicológicos que intervienen en el funcionamiento de las organizaciones, lo cual lleva aparejado el análisis dialéctico de los procesos y las relaciones que entre ellas se suceden

Two-output Class E Isolated dc-dc Converter at 5 MHz Switching Frequency

This paper presents a two output class-E isolated dcdc converter that regulates the output voltages at fixed switching frequency. The converter is simulated at operating frequency of 5 MHz. The converter output power is 40 W and the output voltages are 15 V and 5 V. All the switches operate at zero voltage switching (ZVS) conditions for the full load range. The circuit configuration is simple with small passive components which reduce the size of the converter. The circuit also has very good cross-regulation and an inherent short circuit protection with preserved ZVS condition

Multiple-output Class E Isolated dc-dc Converter

This paper presents a multiple output class-E isolated dc-dc converter that regulates the output voltages at fixed switching frequency. The two output converter is simulated at operating frequency of 5 MHz. The converter output power is 40 W and the output voltages are 15 V and 5 V. All the switches operate at zero voltage switching (ZVS) conditions for the full load range. The circuit configuration is simple with small passive components which reduce the size of the converter. The circuit also has very good cross-regulation and an inherent short circuit protection with preserved ZVS conditions

Modeling, Analysis and Simulation of a DC Distributed Power Architecture for an Airborne Application

This paper describes a design and analysis method for a DC distributed power architecture design in Airborne Application, utilizing simulation. Typically the used system components are commercial off-the-shelf components (COTS) thus complicating the system level analysis and simulation. Within this paper, it is shown how these systems can be designed utilizing simulation results, based on behavioural models of dc/dc converters. Additionally, models for commercial EMI filters are developed. This enables system level simulations and important information from efficiency, transient response, failures and stability is obtained assisting the designer to reach an optimum power system solution with minimum time and effort. Complex systems in avionics require high reliability. Therefore, the system level simulation is an essential tool for reaching the feasible solution complying with all the requirement

Single-Stage Grid-Connected Forward Microinverter with Boundary Mode Control

This paper presents a microinverter to be integrated into a solar module. The proposed solution combines a forward converter and a constant off-time boundary mode control, providing MPPT capability and unity power factor in a single-stage converter. The transformer structure of the power stage remains as in the classical DC-DC forward converter. Transformer primary windings are utilized for power transfer or demagnetization depending on the grid semi-cycle. Furthermore, bidirectional switches are used on the secondary side allowing direct connection of the inverter to the grid. Design considerations for the proposed solution are provided, regarding the inductance value, transformer turns ratio and frequency variation during a line semi-cycle. The decoupling of the twice the line frequency power pulsation is also discussed, as well as the maximum power point tracking (MPPT) capability. Simulation and experimental results for a 100W prototype are enclose

Modeling and Simulation of a Distributed Power System for Avionic Application

This paper describes design and analysis method for a DC distributed power system for Avionic Application utilizing simulation. In order to obtain rapid time to market, the used system components are typically commercial off-the-shelf components (COTS). This complicates the system level analysis and simulation because traditional modeling methods are not applicable. Within this paper, it is shown how these systems can be designed utilizing simulation results based on behavioral models of commercial dc/dc converters. Additionally, models for commercial EMI filters are developed. From the system level simulations important information of the whole system behaviour, such as power consumption, and overall stability is obtained. This assists the designer to reach an optimum power system solution with minimum time and effort. Therefore, the system level simulation is an essential tool for reaching the feasible design solution complying with all the requirement

Forward micro-inverter with primary-parallel secondary-series multicore transformer

This paper presents a primary-parallel secondary-series multicore forward micro-inverter for photovoltaic AC-module application. The proposed solution changes the number of active phases depending on the grid voltage, thus enabling the usage of low-profile unitary turns ratio transformers. Therefore, the transformers are well coupled and the overall performance of the inverter is improved. Due to the multiphase solution the number of devices increases but, the current stress and losses per device are reduced contributing to an easier thermal management. Furthermore, the decoupling capacitor is split between the phases, contributing to a low-profile solution without electrolytic capacitors suitable to be mounted in the frame of a PV module

Non-linear gain - look-up table based approach for modeling a family of DC to DC converters based on transient response analysis

The purpose of this work is to propose a structure for simulating power systems using behavioral models of nonlinear DC to DC converters implemented through a look-up table of gains. This structure is specially designed for converters whose output impedance depends on the load current level, e.g. quasi-resonant converters. The proposed model is a generic one whose parameters can be obtained by direct measuring the transient response at different operating points. It also includes optional functionalities for modeling converters with current limitation and current sharing in paralleling characteristics. The pusposed structured also allows including aditional characteristics of the DC to DC converter as the efficency as a function of the input voltage and the output current or overvoltage and undervoltage protections. In addition, this proposed model is valid for overdamped and underdamped situations