Linear matrix inequality based synthesis of PI controllers for PMSM with uncertain parameters

This paper addresses the design of robust PI controllers for permanent magnet synchronous motors in terms of a linear matrix inequality based problem. A polytopic model of the plant is obtained and validated for the motor uncertain parameters belonging to intervals. The design procedure proposed here encompasses: i. suitable plant uncertainties inclusion and the use of practical design control constraints; ii. robust PI computation based on linear matrix inequalities with a very fast solution; iii. simulation analyses; and iv. experimental evaluations. The robust PI controller can produce superior speed regulation than a PI controller designed only for the nominal parameters, including better disturbance rejection and H-infinity performance. Experimental results confirm the viability of the proposal, which can be seen as an efficient alternative to trade off performance and robustness for PI controllers in this application233310319CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES306197/2015-4não te

Complementando o Aprendizado em Programação: Revisitando Experiências no Curso de Sistemas de Informação da USP

O curso de Bacharelado em Sistemas de Informação da Universidade de São Paulo trabalha pela constante melhoria na formação que oferece para seus alunos, o que requer um trabalho contínuo de inovação e aprimoramento do processo de ensino-aprendizagem executados por seus professores e alunos. Na busca desta melhoria, os professores e alunos vêm realizando algumas ações, dentre as quais estão as experiências apresentadas neste artigo: as disciplinas de Desafios de Programação e o Campeonato de Programação para Calouros. Ambas estão focadas na complementação do aprendizado de lógica de programação, algoritmos e estruturas de dados -- assuntos difíceis do ponto de vista didático, mas imprescindíveis na formação técnica de qualidade. O presente artigo revisita e estende análises sobre essas experiências

Moving in the anthropocene: global reductions in terrestrial mammalian movements

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission

Multiobjective optimization for robust control applied to grid-connected inverters

Este artigo propõe um novo procedimento de projeto para controladores por realimentação de estados com aplicação prática em inversores conectados à rede, levando a resultados em conformidade com a norma IEEE 1547, inclusive para o caso de implementação utilizando um número reduzido de sensores. O procedimento baseia-se na otimização de objetivos considerando estabilidade, erro de rastreamento e atenuação de distúrbios. Um algoritmo genético é utilizado para buscar, orientado por modelos simples, os ganhos de controle, levando a um conjunto de soluções viáveis (fronteira de Pareto). O ganho de controle escolhido possui estabilidade robusta contra incertezas e variações paramétricas, certificada por meio de análise baseada em desigualdades matriciais lineares. Restrições no espaço de busca permitem encontrar, de forma automática, ganhos por realimentação total ou parcial de estados, superando limitações de desigualdades matriciais de sínteses e levando a resultados experimentais de boa qualidade, o que torna este procedimento uma alternativa útil no projeto de controladores robustos para conversores de potência241107115CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO GRANDE DO SUL - FAPERGS465640/2014-1; 306197/2015-423038.000776/2017-5417/2551- 0000517-1This paper proposes a new design procedure for state feedback controllers suitable for practical application in grid-connected inverters, leading to results complying with IEEE 1547 Standard, even with a reduced number of sensors. The procedure relies on the optimization of objectives considering stability, tracking error and disturbance attenuation. A genetic algorithm is used to search, based on simple models, the control gains, leading to a set of viable solutions (Pareto front). The chosen control gain has robust stability against parameter uncertainties and variations certified by means of analysis linear matrix inequalities. Constraints in the search space allow to find full or partial state feedback gains in an automatic way, overcoming limitations of existing synthesis linear matrix inequalities and leading to experimental results of good quality, what makes this procedure a useful alternative on control synthesis for power converter

Effects of body size on estimation of mammalian area requirements

Accurately quantifying species’ area requirements is a prerequisite for effective area-based conservation. This typically involves collecting tracking data on species of interest and then conducting home-range analyses. Problematically, autocorrelation in tracking data can result in space needs being severely underestimated. Based on the previous work, we hypothesized the magnitude of underestimation varies with body mass, a relationship that could have serious conservation implications. To evaluate this hypothesis for terrestrial mammals, we estimated home-range areas with global positioning system (GPS) locations from 757 individuals across 61 globally distributed mammalian species with body masses ranging from 0.4 to 4000 kg. We then applied block cross-validation to quantify bias in empirical home-range estimates. Area requirements of mammals 1, meaning the scaling of the relationship changed substantially at the upper end of the mass spectrum.publishedVersio

Effects of body size on estimation of mammalian area requirements

Accurately quantifying species’ area requirements is a prerequisite for effective area-based conservation. This typically involves collecting tracking data on species of interest and then conducting home-range analyses. Problematically, autocorrelation in tracking data can result in space needs being severely underestimated. Based on the previous work, we hypothesized the magnitude of underestimation varies with body mass, a relationship that could have serious conservation implications. To evaluate this hypothesis for terrestrial mammals, we estimated home-range areas with global positioning system (GPS) locations from 757 individuals across 61 globally distributed mammalian species with body masses ranging from 0.4 to 4000 kg. We then applied block cross-validation to quantify bias in empirical home-range estimates. Area requirements of mammals 1, meaning the scaling of the relationship changed substantially at the upper end of the mass spectrum

Effects of body size on estimation of mammalian area requirements

Accurately quantifying species' area requirements is a prerequisite for effective area-based conservation. This typically involves collecting tracking data on species of interest and then conducting home-range analyses. Problematically, autocorrelation in tracking data can result in space needs being severely underestimated. Based on the previous work, we hypothesized the magnitude of underestimation varies with body mass, a relationship that could have serious conservation implications. To evaluate this hypothesis for terrestrial mammals, we estimated home-range areas with global positioning system (GPS) locations from 757 individuals across 61 globally distributed mammalian species with body masses ranging from 0.4 to 4000 kg. We then applied block cross-validation to quantify bias in empirical home-range estimates. Area requirements of mammals 1, meaning the scaling of the relationship changed substantially at the upper end of the mass spectrum

Data from: Moving in the Anthropocene: global reductions in terrestrial mammalian movements

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission