In this paper is presented a pulse-width-modulation (PWM) technique with neutral point capacitor voltage balancing in single-phase neutral-point-clamped (NPC) converters. The technique is based on the injection of a common mode voltage signal into the sinusoidal modulating signals of the conventional carrier-based PWM. Although several strategies have been reported for such a problem by using the voltage signal injection, the proposed method is very simple with easy implementation. It is presented a set of equations to demonstrate how the injected voltage signal introduces a dc component on the neutral-point current, which can be controlled in order to allow the capacitors voltages balancing.

This paper presents the design and testing of an artificial finger based partly on biomechanics. The prototype was manufactured in acrylonitrile butadiene styrene plastic using a rapid prototyping three-dimensional printer. The flexing of the finger was realized by Ni-Ti shape-memory alloy (SMA) wires with diameters of 0.3 mm, activated by resistive heating. The results obtained show the new prototype to be superior in performance, mainly in terms of angles of rotation of the phalanges, compared with some SMA fingers discussed in the literature.

This paper presents a fuzzy system to control the pressure in a water distribution network, by using valves and controlling the rotor speed of the pumping systems. The variable frequency drive tracks the minimum head of the pumping system, while the control valves have the function of eliminating the excess pressure at various points of the network. The control system can track any reference pressure value and there is no limit for the number of monitored points. Experiments were carried out to demonstrate the fuzzy system's efficiency. By extrapolating the results achieved in the experimental setup to a real hydraulic network with leakages and no pressure control, the volumetric losses could be reduced by more than 56%. The experiments showed that the system is robust enough to control the pressure of an experimental setup of water distribution. Besides, the proposed system can be easily applied to similar water supply systems and would help to reduce the consumption of water and electricity, as well as to reduce the maintenance costs.

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Este trabalho apresenta uma nova estratégia de acionamento para uma mesa de coordenadas XY, denominada de Controle Vetorial Neural, utilizando uma rede neural multicamada (RNMC) atuando como controlador adaptativo direto, cujo algoritmo de aprendizagem se baseia na minimização do erro entre o vetor de posição atualizado e o de referência. Duas estratégias de controle são mostradas. A primeira estratégia é baseada no uso de controladores de posição neurais, independentes, para cada eixo e a segunda é apresentada como principal contribuição deste trabalho e é baseada no uso do Controlador Vetorial Neural. A estratégia proposta é diferenciada dos conhecidos controladores de trajetória por não possuírem controladores independentes para cada eixo. A mesa de coordenadas XY, usada para validação, é uma estrutura de dois graus de liberdade considerada como um manipulador de eixos desacoplados. Resultados experimentais e de simulação mostram o desempenho superior do Controlador Vetorial Neural. Um menor tempo de processamento no uso de uma única rede neural é uma vantagem adicional do uso do Controlador Vetorial Neural em relação aos controladores independentes.