Soft-switching modular multilevel converters for efficient grid integration of renewable sources

The Modular Multilevel Converter (MMC) concept is a modern energy conversion structure that stands out for a number of interesting features that opens wide application chances in Power Systems, for example for efficient grid integration of renewable sources. In these high-voltage, high-power application fields, a high efficiency is mandatory. In this regard, an interesting and promising development opportunity could be to make soft-switching the elementary converters of the submodules (cells), half H-bridges or full H-bridges, obtaining at the same time the advantage of increasing the switching frequency. The ARCP or the AQRDCL soft-switching topologies appear adequate for this purpose. This paper is dedicated to examining these development possibilities

Modelagem e análise da confiabilidade de sistemas

Este trabalho apresenta uma discussão a respeito dos principais métodos e técnicas utilizados na modelagem e na análise da Confiabilidade de sistemas. Primeiramente são apresentados os mais importantes conceitos da área da Engenharia de Confiabilidade, bem como os principais métodos para a análise da Confiabilidade de componentes, que servem de fundamento para a análise da Confiabilidade de sistemas. A utilização das informações de Confiabilidade em ambientes produtivos, bem como as implicações técnicas e gerenciais associadas a metas de Confiabilidade também são sucintamente abordadas. De modo a verificar a utilidade e a aplicabilidade prática dos métodos e algoritmos discutidos, é apresentado um software de apoio: o RelySys (Reliability Software for Systems Analysis). Operando com amostras de dados completas ou censuradas, sua principal função é a de auxiliar o engenheiro de Confiabilidade nas etapas de modelagem e análise da Confiabilidade de sistemas em série, a partir das informações de Confiabilidade dos componentes do sistema.This work presents a discussion about the most useful methods and techniques on systems’ Reliability modeling and analysis. Initially, the most important concepts of the branch of Reliability Analysis and the leading methods on components’ Reliability analysis, which are used as basis on systems Reliability analysis, are presented. The uses of Reliability information on productive environments, as well as the technical and administrative implications, are also discussed. In order to verify the utility and the practical applicability of the methods and algorithms discussed, a software is presented: RelySys (Reliability Software for Systems Analysis). Based on Reliability information about the components of the system, and dealing with censored or non-censored samples, its main function is to provide support for Reliability Engineers in all steps of the Reliability modeling and analysis of series systems

Implementación de un modelo de sistema de gestión de inocuidad en Envases Los Pinos S. A. C.

La presente tesis busca establecer los vínculos estrechos entre los envases de hojalata para alimentos y la seguridad alimentaria para proponer una mejora en las condiciones de fabricación a través de un modelo de sistema de gestión de inocuidad en la empresa Envases Los Pinos S.A.C., puesto que los requerimientos de los clientes cada vez son más exigentes. El estudio se aplicó a las líneas de producción de envases de la empresa, las cuales son identificadas como: Línea de Prensas de Tapas y Línea Automática de Cuerpos Soldados. Se ha realizado un estudio descriptivo aplicando un modelo basado en el Análisis de Peligros y Riesgos en las etapas de proceso, identificando los Puntos de Control Críticos. Se espera que con la aplicación de este modelo la empresa implemente un sistema de gestión de inocuidad que le permita posicionarse en el mercado peruano, obtener las preferencias de consumo de sus clientes procesadores de conservas al cumplir con los requerimientos de sus mercados externos y como consiguiente aumentar la rentabilidad

Sensorless Control with Switching Frequency Square Wave Voltage Injection for SPMSM with Low Rotor Magnetic Anisotropy

High-frequency signal injection sensorless algorithms are widely studied and used for rotor angle estimation in PMSM at low speed or standstill. One of the main drawbacks of such methods is the acoustic noise connected to the voltage injection. In order to minimize this problem, it is advisable to increase the frequency of the injected signal. Thus, many studies focus on square-wave injection at the switching frequency, which is the maximum theoretical frequency. Since these methods exploit the rotor magnetic anisotropy, it is relatively easy to use them in interior PMSMs, where the rotor anisotropy is high. On the contrary, it is hard to exploit them in surface PMSMs, which have an almost symmetric rotor, although a low rotor magnetic anisotropy is still present. In this paper, a sensorless algorithm with switching frequency squarewave injection is developed for surface PMSMs. To increase the signal-to-noise ratio, current oversampling is exploited. The benefits of such a technique are demonstrated with experimental results on a 2 Nm SPMSM

Relación hecha por el presbítero José Espínola Cobo respecto de la situación eclasiástica de Talca desde 1810 a 1910: aproximación crítica al texto

El texto referido fue publicado en  La Revista Católica  en el nº 219 del año 1910. El presente trabajo intenta reflexionar esta relación hecha por el que luego sería el primer gobernador eclesiástico de Talca a partir de 1910, rescatando la coherencia interna del texto, del mismo modo que poner de relieve la visión histórica y los acentos de esta visión que se explicitan  o subyacen al documento mencionado. Se trata de un estudio crítico del texto que pretende develar la mentalidad eclesiástica y sus parámetros para visualizar y concretar el desarrollo de la Iglesia en la época

Surface Permanent Magnet Synchronous Motors’ Passive Sensorless Control: A Review

Sensorless control of permanent magnet synchronous motors is nowadays used in many industrial, home and traction applications, as it allows the presence of a position sensor to be avoided with benefits for the cost and reliability of the drive. An estimation of the rotor position is required to perform the field-oriented control (FOC), which is the most common control scheme used for this type of motor. Many algorithms have been developed for this purpose, which use different techniques to derive the rotor angle from the stator voltages and currents. Among them, the so-called passive methods have gained increasing interest as they do not introduce additional losses and current distortion associated instead with algorithms based on the injection of high-frequency signals. The aim of this paper is to present a review of the main passive sensorless methods proposed in the technical literature over the last few years, analyzing their main features and principles of operation. An experimental comparison among the most promising passive sensorless algorithms is then reported, focusing on their performance in the low-speed operating region

Three-dimensional harmonic oscillator and time evolution in quantum mechanics

The problem of defining time (or phase) operator for three-dimensional harmonic oscillator has been analyzed. A new formula for this operator has been derived. The results have been used to demonstrate a possibility of representing quantum-mechanical time evolution in the framework of an extended Hilbert space structure. Physical interpretation of the extended structure has been discussed shortly, too.Comment: 14 pages; submitted to Phys Rev

Intelligence, Executive Functions and Academic Achievement in Adolescents of 13 and 14 years old

El ámbito educativo, indudablemente, puede beneficiarse de los aportes de las neurociencias, enfoque desde el cual, en este estudio, se plantearon los objetivos de explorar la relación existente entre la capacidad intelectual (CI), las funciones ejecutivas (FE) y el rendimiento académico (RA) en adolescentes; analizar si la CI y las FE constituyen variables predictoras del RA, e indagar el funcionamiento ejecutivo de la muestra según la CI fuera baja o alta. Para ello, se realizó un estudio no experimental, transversal, descriptivo-correlacional, en el que participaron 36 sujetos de 13-14 años. Los instrumentos de evaluación utilizados fueron WISC-IV, BANFE-2 y el registro de calificaciones provisto por la institución educativa. Los datos obtenidos fueron sometidos a análisis descriptivos, de correlación y de regresión. Los resultados arrojaron correlación positiva significativa entre las variables CI y FE, y entre la prueba WISC-IV y RA, determinándose el CI como variable predictiva del RA, mientras que en relación con las FE evaluadas con BANFE-2 solo se encontró asociación estadísticamente significativa con las subpruebas correspondientes al área prefrontal anterior. Además se observaron diferencias significativas entre los grupos de alta y baja CI en las FE de planificación, memoria de trabajo (MT) y fluidez verbal, en favor del grupo de alto desempeño intelectual. La conclusión se centra en la importancia de involucrar los hallazgos sobre los diferentes procesos cognitivos en el diseño de las estrategias pedagógicas para favorecer al máximo el RA del estudiante. Finalmente, las limitaciones versaron en relación con el tamaño muestral, y se proponen futuras líneas de estudio que posibiliten generalizar los resultados.The study of the relationship between executive functions, intellectual abilities, and academic achievement plays an important role in the field of cognitive neuroscience, particularly for their implications in the educational field. Intelligence has been linked to executive functions. In fact, core aspects of intelligence, such as reasoning, problem-solving and planning, are often included in the wide range of frontal lobe functions and over laps with the so-called higher-level executive functions. In addition, executive functioning abilities are associated with skills put in play when participating in learning activities at school. In this sense, different studies have demonstrated that a lower performance on executive function measures typically is associated with a lower performance across different academic areas. The aim of this work was focused on the relationship between intelligence and executive functions, and their ability to predict academic achievement. In the present study, a non-experimental, transversal and descriptive-correlational design was implemented to explore the relationship between intellectual abilities, executive functions, and academic performance in a sample of 37 adolescents (17 girls) aged 13-14 years. The information was collected through the school reports of participants, and their performance on tests BANFE-2 (neuropsychological battery of the executive functions and frontal lobes) and WISC-IV (Wechsler intelligence scale for children 4th Ed.). Also, adolescents were classified into two groups (high- and low performers) based on their performance on the general intelligence score. Participants with IQ scores below the median were assigned to the low-performing group, while participants with IQ scores above the median were assigned to the high-performing group. The data obtained were subjected to descriptive, correlation and regression analyses. Results showed a pattern of positive and significant correlations between executive functions variables (BANFE-2) and intelligence scores (WISC-IV). The 69 % of significant correlations indicated a moderate – strong degree of association (i. e., 49 <r(35) < 73), while the remaining of significant correlations showed a weak degree of association (i. e., 37 <r(35) < 50). Particularly, executive functions variables, such as working memory, mental flexibility, and planning, were highly correlated with the IQ score, verbal comprehension index, and processing speed index. Further, academic achievement was predicted by intelligence scores (i. e., IQ score, verbal comprehension index, working memory index and processing speed index) and variables related to metafunctions (i. e., abstract reasoning and metacognition). On average, intelligence scores and metafunctions explained a 20 % of the variance in academic achievement. Finally, results revealed significant differences according to the general intelligence level of the adolescents, especially in executive function variables that had shown a larger association with intelligence scores. In particular, differences in executive skills between adolescents with high and low intelligence scores, were mainly characterized by differences in the performance of tasks with working memory and/or mental flexibility demands. These results confirm the association between intelligence and executive functions, and the capacity of intelligence abilities and higher-level executive functions in predicting academic achievement in different areas. Likewise, these findings highlight the important role of intelligence and executive functions in learning and academic achievement, and contribute to the consideration of different cognitive domains in the design of pedagogical strategies with the aim of promoting student performance. However, it is difficult to generalize findings beyond the study sample and arrive at more precise conclusions. The sample size was small and the scores were below expected standards in both WISC-IV and BANFE-2. In a future work, would be required a wider experimental study to conduct complex models of analysis that allow more precise and rigorous examinations.Fil: Muchiut, Álvaro Federico. Instituto Superior de Neuropsicologia Numero 166 (uep 166); Argentina. Fundación Centro de Estudios Cognitivos; ArgentinaFil: Vaccaro, Paola. Fundación Centro de Estudios Cognitivos; ArgentinaFil: Pietto, Marcos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina. Instituto Superior de Neuropsicologia Numero 166 (uep 166); Argentin

Implications on the Adaptation of the Wechsler Intelligence Scale for Children IV (WISC-IV) in Argentina: Comparison of the WISC-IV Standardized Data from two Argentine Regions

La utilización de pruebas psicológicas validadas y de confiabilidad comprobadas aportan evidencias valiosas al profesional en una multiplicidad de actividades, que comprenden desde el diagnóstico, el plan y el seguimiento de tratamiento hasta la selección laboral, la orientación vocacional, las pericias judiciales e investigación; sin embargo, no siempre se disponen de baremos adaptados a la región en la que se pretende aplicar un instrumento y, en ocasiones, siquiera corresponden a datos normativos del país. En Argentina, la WISC-IV fue adaptada considerando población perteneciente al Área Metropolitana de Buenos Aires, no se incluye muestra de otras regiones del extenso país. Por lo tanto, se realizó una investigación cuantitativa no experimental, exploratoria- descriptiva, con el objetivo de determinar la importancia de contar con baremos adaptados de la WISC-IV para diferentes regiones de un mismo país; para ello, se analizaron comparativamente los índices obtenidos por 520 escolares de 6 a 14 años (agrupados según los rangos de edad 6-8, 9-11 y 12-14) al aplicar dos baremos argentinos (Buenos Aires y Resistencia) para su corrección mediante un análisis de ANOVA mixto. Los resultados evidenciaron diferencias significativas según el baremo sea de Buenos Aires o de Resistencia, en 4 de los 5 índices de la WISC-IV, al abarcar tanto en aspectos relacionados con el funcionamiento cognitivo general (i.e., CIT), como en campos más específicos (i.e., memoria de trabajo - IMO, velocidad de procesamiento - IVP y razonamiento perceptivo - IRP); además, se observaron diferencias entre baremos en CIT, ICV, IRP e IMO y sugerir comportamientos diferentes en los distintos índices según el tipo de baremo aplicado en los diferentes grupos de edad. Los resultados sugieren que la corrección de la escala a un/a estudiante, según las normativas establecidas para una región con características sociodemográficas distintas a la que pertenece el individuo, podría derivar en errores interpretativos de sus aptitudes cognitivas, por lo que se determina la importancia de contar con adaptaciones de las pruebas psicológicas para arribar a interpretaciones que eviten infra o sobrevalorar sus puntuaciones.The use of validated psychological tests provides valuable evidence to specialists in a multiplicity of activities (e.g., predicting diagnoses, guiding treatment and follow-up plans, guiding the job selection process and vocational orientation, determining disability levels for medico-legal purposes). However, a psychological instrument is not generally adapted and standardized in the country in which it is intended to be applied. In Argentina, the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) was standardized in the Buenos Aires Metropolitan Area; but did not include samples from other regions across the vast country. This situation is problematic, because Argentina presents disparities in its socio-demographic characteristics across the territory, and an accurate interpre- tation of intelligence test performance, depends on the use of appropriately standardized data. Hence, a quantitative non-experimental, exploratory-descriptive study was conducted to determine the importance of obtaining locally standardized data for WISC-IV. To this end, the indices obtained from 520 children and adolescents aged 6 to 14 years (grouped according to age ranges 6-8, 9-11 and 12-14) were comparatively analyzed, by analyzing two Argentine adaptations (Buenos Aires and Resistencia). Results revealed differences between normative data from the country's different regions in four indices, which included both aspects of general cognitive functioning (i.e., CIT) and more specific processes (i.e., working memory - IMO, processing speed - IVP, and perceptual reasoning - IRP). These results suggest that the assessment of students, according to non-locally established standardized data, could lead to interpretative errors regarding their cognitive abilities. Thus, the study contributes to knowledge about the importance of using contextually appropriate standardized data in the implementation of intelligence tests, to arrive at evaluations that avoid over- or under- estimating students' abilities.Fil: Mucchiut, Alvaro. Instituto Superior de Neuropsicologia Numero 166 (uep 166); ArgentinaFil: Vaccaro, Paola. Instituto Superior de Neuropsicologia Numero 166 (uep 166); ArgentinaFil: Pietto, Marcos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina. Instituto Superior de Neuropsicologia Numero 166 (uep 166); ArgentinaFil: Dri, Constanza. Instituto Superior de Neuropsicologia Numero 166 (uep 166); Argentin

Emotionality, Behavior, Social Skills, and Executive Functions in Initial Level Children

Durante el nivel inicial, los infantes suelen expresar respuestas emocionales y conductuales de manera impulsiva, dado que carecen de la aptitud de abstenerse de efectuar conductas que no son apropiadas a la ocasión. En este punto, las Habilidades Sociales (HHSS) y las Funciones Ejecutivas (FE) serán facilitadoras de la interacción asertiva con otros, favoreciendo en control comportamental y evitando los Problemas de Conducta (PC). El objetivo de este estudio fue analizar la correlación entre las FE, la percepción parental en relación a las emociones, y la percepción de docentes respecto de las HHSS y la conducta en niños del nivel inicial de educación; a tal fin se realizó un estudio cuantitativo, transversal, descriptivo-correlacional, en base a un diseño no experimental. La muestra estuvo integrada por 36 niños/as de nivel inicial, a quienes se les administró una batería neuropsicológica, además se incluyeron dos cuestionarios, uno para padres y otro para docentes. Se encontró correlación entre HHSS y PC; entre Planeación y Emociones; y entre Atención y Concentración y Memoria de Trabajo. Se concluye que los niños de nivel inicial poseen una conducta socialmente habilidosa, y manejan sus emociones sin dificultad indistintamente del sexo, según la perspectiva parental y docente.Fil: Mucchiut, Alvaro. Centro de Estudios Cognitivos; ArgentinaFil: Dri, Constanza Ayelen. Centro de Estudios Cognitivos; ArgentinaFil: Vaccaro, Paola. Centro de Estudios Cognitivos; ArgentinaFil: Pietto, Marcos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentin