New integrated Zeta and Cuk inverters intended for standalone and grid-connected applications

This paper presents new inverter topologies based on the integration of a DC to DC Zeta or Cuk converter with a voltage source inverter (VSI). The proposed integration procedure aims to reduce the amount of components, meaning lower volume, weight and costs. In this context, new families of single-phase and three-phase integrated inverters are also presented. Therefore, considering the novelty for Zeta and Cuk integrated inverters structures, the proposed single-phase and three-phase inverters versions are analyzed for grid-tied and stand-alone applications. Furthermore, in order to demonstrate the feasibility of the proposal, the main simulation and experimental results are presented. © 2011 IEEE.

Power flow optimization for grid connected inverter using evolutionary algorithm and additional control loop

In this work it is proposed to validate an evolutionary tuning algorithm in plants composed by a grid connected inverter. The optimization aims the tuning of the slopes of P-Ω and Q-V curves so that the system is stable, damped and minimum settling time. Simulation and experimental results are presented to prove the feasibility of the proposed approach. However, experimental results demonstrate a compromising effect of grid frequency oscillations in the active power transferring. In addition, it was proposed an additional loop to compensate this effect ensuring a constant active power flow. © 2011 IEEE.

A new design methodology for multipulse rectifiers with Delta auto-connected transformers and a retrofit application in Adjustable Speed Drives (ASDs)

Multipulse rectifiers can replace a conventional six pulse three-phase rectifier (diode bridge) providing a DC voltage with low ripple, low Total Harmonic Distortion of current (THDi) and a high Power Factor (PF). In this context is presented a multipulse rectifier with generalized Delta-differential autotransformer topology, which can provide any level of DC output voltage for any level of three-phase AC input voltage. This paper presents all the possible configurations for Delta topology in order to choose, through graphics, one configuration that presents reduced weight and volume. The average voltage on the DC bus must be compatible with the DC voltage in the six pulse rectifier used in commercial ASDs. Therefore, it is possible to apply the retrofit technique to replace the conventional bridge rectifier by the proposed multipulse rectifier. Based on mathematic models and simulation results, an 18-pulse rectifier with Delta topology, 220 V of line voltage, 315 V of DC output, and rating 2.5 kW of power was designed, implemented and applied for three different commercial ASDs. Experimental results as voltage and current waveforms and results about PF and THDi will be presented. © 2012 IEEE.

Culture, discourse (self-expression) and social development in the Caribbean

Includes bibliography

Culture, discourse (self-expression) and social development in the Caribbean

Includes bibliography

Programas de la Organización de Estados Americanos relacionados con la urbanización en América Latina = Programmes of the Organization of American States connected with urbanization in Latin America

Los documentos del Seminario fueron publicados por UNESCO en 1961 con el título: La urbanización en América Latina/Urbanization in Latin America

Structure, characterization and near-infrared emission of a novel 6-connected uninodal 3D network of Nd(III) containing 2,5-thiophenedicarboxylate anion

The novel coordination polymer with the formula {[Nd2(2,5-tdc)3(dmf)2(H2O)2].dmf.H2O}n (2,5-tdc2-=2,5-thiophedicarboxylate anion and dmf=dimethylformamide) has been synthesized and characterized by thermal analysis (TG/DTA), vibrational spectroscopy (FTIR) and single crystal X-ray diffraction analysis (XRD). Structure analysis reveals that Nd(III) ions show dicapped trigonal prism coordination geometry. The 2,5-tdc2- ligands connect four Nd(III) centers, adopting (κ1 - κ1) - (κ1 - κ1) - μ4 coordination mode, generating an interesting 6-connected uninodal 3D network. Photophysical properties were studied using diffuse reflectance spectroscopy (DR) and excitation/emission spectra. The photoluminescence data show the near infrared emission (NIR) with the characteristic 4F3/2→4IJ (J=9/2, 11/2 and 13/2) transitions of Nd(III) ion, indicating that 2,5-tdc2- is able to act as a sensitizer for emission in NIR region. © 2013 Elsevier B.V.

A investigação sobre a própria prática de um professor iniciante sob o olhar da teoria da recontextualização

Pós-graduação em Educação para a Ciência - FC

Draft project: creole discourse and social development

Presenta el proyecto preliminar sobre la promocion del desarrollo social y el lenguaje criollo en el Caribe. Incluye antecedentes, objetivos, programa de actividades, instituciones regionales participantes, y aspectos institucionales.

Creole discourse and social development

Contiene el informe del proyecto sobre la promoción del desarrollo social y el lenguaje criollo en el Caribe

A nação é católica: educação e cidadania nas primeiras décadas republicanas (1890 a 1930)

Pós-graduação em História - FCHS

A censura no Pasquim (1969-1975): as vozes não-silenciadas de uma geração

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Em busca do discurso poético de Aristides Klafke: marginália e contracultura

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Reflections on the need for a new discourse on development

This issue of the FAL bulletin reflects on the need to place a new discourse at the centre of the academic, social and political debate, in relation to developing infrastructure services in a sustainable way.

Ecos da modernidade: uma análise do discurso sobre o cinema ambulante em São Luís-MA

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)