Analysis of power converters with devices of SiC for applications in electric traction systems

This article presents the analysis of two topologies of power converters. Voltage Source Inverter (VSI) and Current Source Inverter (CSI) proposals for traction system applications, these topologies are implemented with silicon carbide devices. The use of SiC semiconductors allow working at high switching frequency (100KHz), increase the working temperature range and decreasing power losses during conduction and activation of the semiconductors. The objective is analyze these topologies and select the one that provides the best performance and behavior at high frequency to improve it on a electric traction system.Postprint (author's final draft

Development of an Emergency Radio Beacon for Small Unmanned Aerial Vehicles

Emergency locator transmitters (ELTs) used to locate manned aircrafts are not well suited to find and recover small crashed unmanned aerial vehicles (UAVs). ELTs utilize an international satellite system for search and rescue (Cospas-Sarsat System), which should leverage its expensive resources to save lives as a priority. Besides, ELTs are too big and heavy to be used within small UAVs. Some of the existing solutions for this problem are based on receivers that detect signal strength, which may be a long and tedious process not suitable for user needs. Others do not have enough range or require radio license and expensive amateur radio receivers. This paper presents an emergency radio beacon specifically designed to locate small UAVs. It is triggered automatically in the event of a crash and allows finding and recovering a crashed UAV in a fast and simple way. It meets not only the required specifications of user-friendliness, size and weight of this kind of application, but also it is a high precision and low cost device. Besides, it has enough range and endurance. The experiments carried out show the operation of the proposed system

Los pichones de Darwin y la evolución de los columbiformes: recapitulación de genes ancestrales

To commemorate the sesquicentennial of Charles Darwin´s On the Origin of Species by Means of Natural Selection, we address an essential topic in this publication. Domestic pigeons were extremely important in shaping Darwin’s theory of evolution: pigeons featured prominently not only in his Origin of Species, but also in his treatise on Variation under Domestication, in his Descent of Man and finally in his Expression of Emotions. Darwin saw the process of domestication as solid evidence demonstrating the power of selection. He argued convincingly that all domestic pigeon breeds (some 150 in his day) descended from one ancestral species, the Rock Dove (Columba livia), and that from this single species, humans selected directionally for colors, sizes, shapes, peculiarities of bill shape and length, plumage characteristics and voice qualities. While these domestic races achieved remarkable morphological differentiation under selection in the course of human generations, extant genera of pigeons (Columbiformes) have attained similar traits during the course of natural selection in the wild. We present a comparison of such characters between modern domestic breeds of the Rock Dove, the original Darwin´s Pigeons plus new breeds, and wild pigeon species to encourage further studies on their evolution in the light of molecular techniques not available at Darwin´s time.Dentro del marco conmemorativo del 150 aniversario de El Origen de las Especies por Medio de la Selección Natural de Charles Darwin, se presenta un ensayo de un tema esencial de esta publicación. Los pichones domésticos tuvieron un lugar destacado en la conformación de la teoría de evolución de Darwin: no sólo jugaron un papel fundamental en El Origen de las Especies, sino también en su tratado sobre Variación en Domesticación, en La Descendencia del Hombre y finalmente en Expresión de Emociones. Darwin vio en el proceso de domesticación una evidencia sólida para demostrar el poder de la selección. Él arguyó de manera convincente que todas las razas de pichón (unas 150 en su época) provenían de una sola especie ancestral, la paloma doméstica (Columba livia). De esta especie única, los humanos seleccionaron direccionalmente colores, tamaños, formas, particularidades en la forma y longitud del pico, características del plumaje y cualidades vocales. Mientras estas razas domésticas adquirieron una diferenciación morfológica impresionante bajo selección en el curso de generaciones humanas, los géneros actuales de los pichones (Columbiformes) han adquirido rasgos similares durante el curso de la selección natural en la vida silvestre. En este trabajo se hace una comparación entre las razas actuales de la paloma doméstica, los pichones de Darwin originales más otros obtenidos posteriormente, y varias especies de pichones silvestres. De esta forma se desea alentar el estudio, en razas domésticas y especies silvestres, sobre la evolución de los rasgos morfológicos que cautivaron a Darwin, a la luz de técnicas moleculares que aún no se desarrollaban en su tiemp

A neural blockchain for a tokenizable e-Participation model

Currently, Distributed Ledger Technologies (DLTs) and, especially, Blockchain technology represent a great opportunity for public institutions to improve citizen participation and foster democratic innovation. These technologies facilitate the simplification of processes and provide secure management of recorded data, guaranteeing the transmission and public transparency of information. Based on the combination of a Blockchain as a Service (BaaS) platform and G-Cloud solutions, our proposal consists of the design of an e-Participation model that uses a tokenizable system of the actions and processes undertaken by citizens in participatory processes providing incentives to promote greater participation in public affairs. In order to develop a sustainable, scalable and resilient e-Participation system, a new blockchain concept, which organizes the blocks as a neural system, is combined with the implementation of a virtual token to reward participants. Furthermore, this virtual token is deployed through a smart contract that the block itself produces, containing information about the transaction and all the documents involved in the process. Finally, our Neural Distributed Ledger (NDL) framework facilitates the interconnection of blockchain networks in a transparent, certified, secure, auditable, scalable and traceable way

Sincronicidad de ciclos económicos en América Latina: motivacion para su estudio y sumario de Metodologías aplicadas

Sincronicidad de ciclos económicos en América Latina: motivacion para su estudio y sumario de Metodologías aplicada

La ayuda internacional al desarrollo : retórica y realidad

RESUMEN: La ayuda externa al desarrollo ha sido un tema polémico y la evidencia empírica respecto a su eficacia es mixta. En este artículo se presenta una breve reseña de la literatura y se describe su comportamiento en las últimas cinco décadas. Pese a que muchos estudios muestran impactos poco significativos en el crecimiento y en la pobreza, la posición dominante claramente busca mantener los flujos de ayuda a los países en desarrollo. Dado que una parte importante de investigaciones está enfatizando en la necesidad de adoptar una visión más desagregada de la ayuda, tanto con respecto a los diversos aspectos políticos e institucionales de los países como en relación con sus diferentes modalidades, quizás este enfoque pueda proporcionar recomendaciones de política más confiables.ABSTRACT: International aid to development has been a controversial topic and empirical evidence in this regard has been mixed. This article presents a short review of the literature and it describes its evolution in the last five decades. Despite the fact that many studies show impacts of little significance to growth and poverty, the dominant view clearly seeks to maintain aid flows to developing countries. Given that an important part of research studies emphasizes the need of adopting a less aggregated view of aid, both in respect to different political and institutional aspects of countries as well as their diverse natures; perhaps this view can offer recommendations for more reliable policy

Solidaridad intergeneracional, Tecnología y Arteterapia.

Resumen Es una realidad incuestionable que el proceso de envejecimiento es un fenómeno global que afecta a todas las sociedades. En este sentido, las relaciones intergeneracionales se interpretan como un tipo de solidaridad que surge como deseable y necesaria, pero que indudablemente plantea una serie de dificultades asociadas a las nuevas formas de vida. Así por ejemplo, desde un punto de vista arquitectónico, los edificios de temática intergeneracional parecen relativamente novedosos, si bien están proliferando especialmente en los últimos años; con propuestas concretas sobre todo en lo relativo a compartir espacios comunes y experiencias, por lo que se trata de un enfoque diferente al tradicional y que parece presentar un enorme potencial futuro. Por otro lado, disciplinas como la Domótica e incluso la Robótica contribuyen a que las personas con necesidades especiales ganen en independencia y autoestima, pero especialmente en calidad de vida. Con idéntico enfoque tecnológico, determinadas propuestas de arte y terapia pueden sin duda jugar un papel relevante en relación con las Nuevas Tecnologías, especialmente aquellas relacionadas con prácticas o experiencias socio-relacionales, si bien también con otras propuestas orientadas hacia la seguridad psicológica y el bienestar personal y grupal. Abstract It is an undeniable reality that the process of aging is a global phenomenon that affects all societies. In this sense, intergenerational relationships are interpreted as a kind of solidarity that emerges as desirable and necessary, but certainly raises a number of difficulties associated with new life forms. For example, from an architectural point of view, inter-themed buildings seem relatively new, but are especially rampant in recent years; with concrete proposals in particular as regards common areas and share experiences, so it is a different from the traditional approach that seems to present an enormous future potential. On the other hand, disciplines such as robotics Automation and even help people with special needs gain in independence and self-esteem, but especially in quality of life. With the same technological approach, proposals of art and therapy can certainly play an important role in relation to new technologies, especially those related to socio-relational practices and experiences, but also with other proposals oriented safety and psychological well-being personal and group

Control method of impedance network in SiC power converters for HEV/EV

Silicon carbide (SiC) devices provide significant performance improvements in many aspects, including lower power dissipation, higher operating temperatures, and faster switching, compared to conventional Si devices. All these features helped increase the interest in the applications of these devices for electric drive systems. The inclusion of an impedance network to elevate DC voltage would improve performance of an electric-traction system, because the topologies of impedances networks can eliminate the need of a DC-DC converter. However, it is important to know control methods that applicable to this type of topologies to systems that are more efficient. This paper presents the analysis of a control method in a power converter topology using SiC devices with an impedance network to elevate DC voltage for electric traction applications. The proposed analisys includes the implementation of a control method in Current Fed Quasi-Z topology, with 100 kHz switching frequency, and its analysis using the simulation of the control method, the power losses in SiC devices and the stress on passive components in the impedance network. Finally, the obtained results are compared with a conventional Current Fed Quasi-Z topology built with silicon devices at a low switching frequency (2 KHz).Postprint (author's final draft

Implementation of high frequency SVM in a digital system for CS-SiC inverter

The operation of current source inverters at high frequency allows to reduce the size of the input coil and output filters. These advantages allowed to obtain converters with better performance and to reduce the size and weight of the passives elements, decreasing the manufacturing costs and while keeping the current harmonic distortion low. For these reasons, it is necessary to implement a modulation technique that allows the converter to work at a higher frequency 100 KHz. This article presents the design and implementation of a Space Vector Modulation (SVM) technique for high switching frequencies for a Current Source Inverter (CSI) topology implemented with SiC devices. The technique is programmed and implemented in a PIC 24FJ256GA406 microcontroller, for the activation and control of SiC devices in each leg of power converter.Postprint (author's final draft

La integración de la educación ambiental en la ESO : datos para la reflexión

We present in this paper the analysis and principal results of a research carried out among 438 teachers and 126 headmasters. The issues concern the situation of environmental education in Obligatory Secondary School. The purpose of the study was to identify teacher and headmaster's opinions, perceptions and feelings about the situation of environmental education in their centres