Asimetría de información

En el presente escrito reviso los aportes que hace la economía de la información, para la explicación de fallos del mercado ante un problema de información asimétrica. Para desarrollar el texto, parto de la revisión de las propuestas teóricas de George Akerlof, Michael Spence y Joseph Stiglitz, mostrando algunos de sus análisis en la búsqueda de aminorar la presencia de asimetría de información, selección adversa y riesgo moral. Las teorías revisadas son aplicadas para explicar la información asimétrica en el mercado de productos libres de agroquímicos

Construcciones en torno a un territorio solidario. La Red de Alternativas Solidarias (RASOL)

Este capítulo muestra una experiencia que conecta el trabajo educativo y de organización de comunidades en la Sierra de Manantlán en Jalisco, con consumidores organizados en la ciudad de Guadalajara, México. La conjunción de esfuerzos de articulación se orienta hacia la construcción de territorios solidarios, más allá de la visión sesgada de las reglas de mercado

Dispositivo electrónico para respaldo satelital de equipos de localización vehicular automática, utilizando la red Iridium

Context: This paper presents the design and development of an electronic device that operates as a satellite backup channel for automatic vehicle location (AVL) equipment, whose only communication channel is the cellular network. Method: The design, manufacture and assembly of the hardware followed 4 phases, and it was aligned with the IPC 2221 standard. This allowed improving the design experience and guaranteed the correct electrical operation in the final product. Results: The information sent by the developed device corresponds to the data generated by the AVL device, which indicates that the information processing was correctly designed. Additionally, it was possible to obtain a functional and versatile device in which the blocks were correctly integrated; its firmware was designed to receive future updates that improved and expanded its capacity and compatibility with other devices. Conclusions: The final product, which works with the Iridium network, seeks to satisfy the technological requirements of the freight transport sector in Colombia with a low-cost, versatile, and easily integrated solution. The implementation of this type of technologies expands the capacity of tracking mobile assets, even in places where there is no cellular network coverage. Acknowledgements: The authors thank the Escuela Colombiana de Ingeniería Julio Garavito for funding this study.Contexto: Este articulo presenta el diseño y desarrollo de un dispositivo electrónico, que funciona como canal de respaldo satelital para equipos de localización vehicular automática (AVL), cuyo único canal de comunicación es la red celular. Método: El diseño, fabricación y ensamblaje del hardware siguió cuatro fases y estuvo alineado con el estándar IPC 2221. Esto permitió mejorar la experiencia del diseño y garantizó el correcto funcionamiento eléctrico en el producto final. Resultados: La información enviada por el dispositivo desarrollado corresponde a los datos generados por el dispositivo AVL, lo que indica que el procesamiento de la información fue diseñado correctamente. Además, fue posible obtener un dispositivo funcional y versátil cuyos bloques se integraron correctamente; su firmware fue diseñado para recibir futuras actualizaciones que mejoraran y ampliaran su capacidad y compatibilidad con otros dispositivos. Conclusiones: El producto final, que opera con la red Iridium, busca satisfacer las necesidades tecnológicas del sector de transporte de carga en Colombia con una solución versátil, de bajo costo y de fácil integración. Con el uso de este tipo de tecnologías, se amplía la capacidad de rastrear activos móviles, aun en zonas donde no existe cobertura de redes celulares. Agradecimientos: Los autores agradecen a la Escuela Colombiana de Ingeniería Julio Garavito por el financiamiento del estudio.

Editorial: Grid Connection of Converters in Renewable Applications

Energy generated from renewable sources is fed into the grid by means of electronic power converters. These can be supervised at system (grid) level to coordinate all productions points together with storages and loads. Regulations impose power supply quality requirements regarding harmonics, grid fault response and low voltage ride through (LVRT). The progress of distributed generation presents challenges to converters such as island mode operation, voltage and frequency regulation, simulation, etc. New collaborative solutions for “more smart” microgrids must be included to improve power quality, reliability, service quality and duty. Wind turbines employing double-fed induction generators (DFIG) use two converters, one for the rotor side and one for the generator side. To improve the performance during severe grid failures, in Okedu and Barghash the advantages of using alternative configurations to the two-level converter, such as the parallel interleaved 2-level inverter, and the 3-level inverter, have been investigated. It has also been investigated to replace the classical dq-PLL with a new PLL, and to include a series dynamic braking resistor (SDBR) between the converters and the three-phase connections. Wind turbines must meet strict requirements, in terms of their behavior, in the event of grid failures, which are regulated by the LVRT regulations in each country. These regulations indicate, by means of voltage and time graphs, how long the wind turbines must remain connected depending on the depth of the faults. In addition, the limits of active and reactive power that can be exchanged during faults are established. The aim is to avoid cascading disconnections of wind turbines that would compromise the stability of the grid. In Okedu and Barghash, the effect of various elements in improving the behaviour of a DFIG against grid faults has been investigated. The first of these elements is the parameters of the IGBTs, concluding that the on-resistance has the greatest influence. The second is the use of a new PLL, and the third is the use of a SDBR during a grid failure. It was found that all of them could improve the performance of the generator in the event of a grid failure. When a wind turbine uses a permanent magnet synchronous generator (PMSG), 100% of the energy generated passes through both converters. In Okedu and Barghash, the control systems of the generator-side and grid-side converters have been considered; several scenarios regarding the turn on resistance of the IGBTs have been considered, and their behaviour during grid faults has been analysed. Generator performance has also been studied with and without the use of a DC-DC converter for overvoltage protection. The main generators used in wind turbines are DFIG and PMSG. In Okedu et al., a comparison of the behaviour of both wind turbines against grid faults has been carried out in various scenarios with different values of generator parameters. The number of converters, associated with renewable generation, connected to the grid has increased significantly lately. This can affect the dynamic response, especially during disturbances, but it can also provide new grid support functionalities if information on the oscillation characteristics is available. Through the use of artificial intelligence, in Baltas et al. the abilities to predict and damp electromechanical oscillations have been improved. With the constant increase in the number of wind turbines connected to the grid, it is very important to have the ability to maintain grid frequency control. In Okedu and Barghash, a work has been presented to stabilise the wind farm during periods of wind speed change by using capacitors connected via a DC-DC converter and a grid-connected DC-AC converter. It was concluded that higher values of the DC-DC converter time constant lead to better performances during load transients. A system including two steam turbines and two squirrel cage induction generators was used in the experiments. Microgrids bring power generation closer to the places of consumption to reduce the saturation of distribution lines. They consist of renewable generation, energy storage and fossil fuel generation. They have three levels of control, where the primary level is the closest to the converters, and the tertiary level, the most external and slowest, performs general monitoring functions. The paper (Buraimoh et al.) focuses on the secondary control functions related to grid failure performance. It proposes a distributed control between inverters and is based on fast detection techniques (fast Delayed Signal Cancellation, DSC), with the objective of a fast control of active and reactive power. A robust transition method between fault mode and normal mode is proposed. Accurate coordination and power sharing between distributed energy resources is achieved. Some energy conversion systems are so complex that they are very difficult to build and test in the laboratory. These include the study of high voltage direct current (HVDC) transmission when several modular multilevel converters (MMC) are involved together with DC grid failure protection elements. In Wang et al., a system including a simulated part (two digitally simulated MMC) and a physical part (two MMC) has been experimented with. The coupling between the two parts has been carried out by means of A/D and D/A converters and power amplifiers

Fortalecimiento de la identidad propia a través de la enseñanza de la medicina tradicional en los estudiantes del grado segundo de la Institución Educativa San José Calabazal desde el área de ciencias naturales

Durante el desarrollo de este trabajo se tuvo en cuenta las formas como lograr superar la problemática que hay en los estudiantes de la institución educativa San José Calabazal, en dicho establecimiento se evidenció el desinterés por la medicina tradicional, el principal causante ha sido la aculturación porque se ha descuidado la cultura propia de la comunidad y las prácticas tradicionales, y se ha acogido otras formas culturales. Dentro de este trabajo el objetivo general es el fortalecimiento de la identidad propia a través de la enseñanza de la medicina tradicional en los estudiantes del grado segundo de la institución educativa san José calabazal desde la enseñanza de las ciencias naturales, y para lograr este objetivo se construyó una malla curricular con recursos etnopedagogicos, centrándose en el aprender haciendo, que consiste en que el estudiante realice sus actividades desde la teoría y la práctica teniendo en cuenta los conocimientos previos como fuentes primarias, estos conocimientos se obtienen a través de la entrevista como herramienta principal y realizando las acciones aprendidas en el entorno. Al principio los estudiantes no se identificaron con la medicina tradicional, luego de aplicar la metodología pedagógica se fueron apoderando del tema y actualmente se encuentran muy interesados por conocer todas las plantas medicinales que hay en la región y tienen como propósito aprender a tratar algunas enfermedades, al tiempo que han fortalecido su identidad cultural, pues reconocen los saberes de su comunidad y se sienten parte de esa identidad y con la responsabilidad de transmitir los saberes que adquirieron.During the development of this work took into account the ways to overcome the problems that are in the students of the educational institution San José Calabazal, in that establishment evidenced the disinterest in traditional medicine, the main cause has been acculturation because the traditional culture of the community and traditional practices have been neglected, and other cultural forms have been accepted. Within this work the general objective is the strengthening of one's identity through the teaching of traditional medicine in the students of the second degree of the san José calabazal educational institution from the teaching of the natural sciences, and to achieve this goal it is built a curriculum with ethno-pedagogical resources, focusing on learning by doing, which consists of the student performing their activities from theory and practice taking into account previous knowledge as primary sources, this knowledge is obtained through the interview as a tool principal and performing the actions learned in the environment. At first the students did not identify with traditional medicine, after applying the pedagogical methodology they took over the issue and are currently very interested in knowing all the medicinal plants that are in the region and have the purpose of learning to treat some diseases, At the same time they have strengthened their cultural identity, because they recognize the knowledge of their community and feel part of that identity and with the responsibility of transmitting the knowledge they acquired

Fertilización por sitio específico en un cultivo de maíz (zea mays l.) en la sabana de bogotá

Se realizó un ensayo en el Centro Agropecuario Marengo (CAM), Sabana de Bogotá, para evaluar el manejo de la fertilidad por sitio específico en un cultivo de maíz. Se instaló una cuadrícula regular de 32 puntos (25 m x 25 m) para muestreo de variables del suelo y de desarrollo y rendimiento del cultivo. Mediante análisis de componentes principales de variables químicas del suelo y su humedad y de rendimiento del cultivo inmediatamente anterior, se identificaron dos zonas de manejo de la fertilidad. En cada una se aplicó un tratamiento de fertilización, considerando la variabilidad específica del suelo (AP1 y AP2) y un testigo con fertilización convencional (CAM1 y CAM2). Las variables evaluadas en los 32 puntos fueron: contenido de humedad y densidad aparente, a 2 profundidades, 110 días después de siembra (dds); altura de planta a 55, 90 y 140 dds; índice foliar a 140 dds; análisis foliar a 150 dds; mazorcas cosechadas, hileras por mazorca, granos por hilera, peso mazorca con y sin amero a 160 dds. Para el análisis de datos se usó estadística descriptiva y geoestadística, incluyendo análisis estructural, kriging y validación cruzada; igualmente se realizó un análisis de costos y beneficios, mediante presupuestos parciales, comparando AP1 y AP2 con CAM1 y CAM2. La metodología usada permitió identificar posibles distancias de muestreo para manejo de la fertilidad por sitio específico. Los mayores rendimientos y beneficios financieros se obtuvieron en AP1. Este artículo presenta resultados y recomendaciones para el manejo de la fertilidad por sitio específico en maíz para la zona

Seminario Permanente de Economía Social y Solidaria

El Seminario Permanente de Economía Social y Solidaria nació en 2020, con el objetivo de que profesores del iteso, de diferentes áreas y con distintas lógicas de trabajo, se reunieran en un espacio de diálogo y reflexión colectiva para tener una mayor articulación. Desde esa fecha, se han realizado siete sesiones en las que se han presentado diversos trabajos, desde dentro y fuera de la universidad, que abonan al fortalecimiento del abordaje relacionado con la economía social y solidaria, que han ayudado a consolidar un espacio interdepartamental con participación de la Dirección General Académica y la Dirección de Integración Comunitaria. Mirar desde la complejidad el trabajo que hacemos en la universidad en torno a esta área de estudio, nos invita a fortalecerlo, incorporando cada vez con mayor fuerza una perspectiva inter y transdisciplinar, y nos ayuda a visibilizar y dinamizar otras formas de organizar el quehacer universitario

Open Source Robot Localization for Non-Planar Environments

The operational environments in which a mobile robot executes its missions often exhibit non-flat terrain characteristics, encompassing outdoor and indoor settings featuring ramps and slopes. In such scenarios, the conventional methodologies employed for localization encounter novel challenges and limitations. This study delineates a localization framework incorporating ground elevation and inclination considerations, deviating from traditional 2D localization paradigms that may falter in such contexts. In our proposed approach, the map encompasses elevation and spatial occupancy information, employing Gridmaps and Octomaps. At the same time, the perception model is designed to accommodate the robot's inclined orientation and the potential presence of ground as an obstacle, besides usual structural and dynamic obstacles. We have developed and rigorously validated our approach within Nav2, and esteemed open-source framework renowned for robot navigation. Our findings demonstrate that our methodology represents a viable and effective alternative for mobile robots operating in challenging outdoor environments or intrincate terrains

Enhanced controller for grid-connected modular multilevel converters in distorted utility grids

This paper is about the control of Modular multilevel converters, an innovative technology in the design of converters, which is beginning to be included in real installations. Papers about this topic include simulation models, circulating current reduction, voltage modulators, capacitor voltage balancing and control issues. The scheme for current source regulation used in this article includes all control loops, which are, from the outermost to innermost, DC bus voltage regulator, current regulator, voltage modulator, capacitor voltage balancing, and a PLL for the synchronization to the grid. Disposition-sinusoidal pulse width modulation is used as the voltage modulator, and an enhanced control strategy in the stationary reference frame for 3-phase MMCs is used for the inner current control loops. Very detailed simulations of the complete control system have been performed for both the enhanced control strategy in the stationary reference frame, and the well-known control in the synchronous reference frame, as well as some experiments using the hardware-in-the-loop simulation technique. The validation of these control strategies is made by a comparison of the capability of each one to compensate the harmonic distortions of the utility grid according to the grid code. The correct operation has been tested in the case of a strong/weak grid, unbalances and grid failures.This work has been partially supported by a grant from the Spanish Government as a part of 673 Project Ref. TEC2016-80136-P, entitled “Nuevas topologías para convertidores en MT para grandes 674 Instalaciones Fotovoltaicas” (A. B. Rey-Boué

Structural brain changes in patients with persistent headache after COVID-19 resolution

Producción CientíficaHeadache is among the most frequently reported symptoms after resolution of COVID-19. We assessed structural brain changes using T1- and diffusion-weighted MRI processed data from 167 subjects: 40 patients who recovered from COVID- 19 but suffered from persistent headache without prior history of headache (COV), 41 healthy controls, 43 patients with episodic migraine and 43 patients with chronic migraine. To evaluate gray matter and white matter changes, morphometry parameters and diffusion tensor imaging-based measures were employed, respectively. COV patients showed significant lower cortical gray matter volume and cortical thickness than healthy subjects (p < 0.05, false discovery rate corrected) in the inferior frontal and the fusiform cortex. Lower fractional anisotropy and higher radial diffusivity (p < 0.05, family-wise error corrected) were observed in COV patients compared to controls, mainly in the corpus callosum and left hemisphere. COV patients showed higher cortical volume and thickness than migraine patients in the cingulate and frontal gyri, paracentral lobule and superior temporal sulcus, lower volume in subcortical regions and lower curvature in the precuneus and cuneus. Lower diffusion metric values in COV patients compared to migraine were identified prominently in the right hemisphere. COV patients present diverse changes in the white matter and gray matter structure. White matter changes seem to be associ- ated with impairment of fiber bundles. Besides, the gray matter changes and other white matter modifications such as axonal integrity loss seemed subtle and less pronounced than those detected in migraine, showing that persistent headache after COVID-19 resolution could be an intermediate state between normality and migraine.Gerencia Regional de Salud (GRS) de Castilla y León, (GRS 2284/A/2020)Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL