Stability analysis of power systems described with detailed models by automatic method

The power system stability analysis is approached taking into explicit account the dynamic performance of generators internal voltages and control devices. The proposed method is not a direct method in the usual sense since conclusion for stability or instability is not exclusively based on energy function considerations but it is automatic since the conclusion is achieved without an analyst intervention. The stability test accounts for the nonconservative nature of the system with control devices such as the automatic voltage regulator (AVR) and automatic generation control (AGC) in contrast with the well-known direct methods. An energy function is derived for the system with machines forth-order model, AVR and AGC and it is used to start the analysis procedure and to point out criticalities. The conclusive analysis itself is made by means of a method based on the definition of a region surrounding the equilibrium point where the system net torque is equilibrium restorative. This region is named positive synchronization region (PSR). Since the definition of the PSR boundaries have no dependence on modelling approximation, the PSR test conduces to reliable results. (C) 2008 Elsevier Ltd. All rights reserved.

Melhora da estabilidade dinâmica de sistemas elétricos de potência multimáquinas usando o dispositivo facts thyristor-controlled series capacitor - TCSC

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Design of a control system using linear matrix inequalities for the active vibration control of a plate

The study of algorithms for active vibration control in smart structures is an area of interest, mainly due to the demand for better performance of mechanical systems, such as aircraft and aerospace structures. Smart structures, formed using actuators and sensors, can improve the dynamic performance with the application of several kinds of controllers. This article describes the application of a technique based on linear matrix inequalities (LMI) to design an active control system. The positioning of the actuators, the design of a robust state feedback controller and the design of an observer are all achieved using LMI. The following are considered in the controller design: limited actuator input, bounded output (energy) and robustness to parametric uncertainties. Active vibration control of a flat plate is chosen as an application example. The model is identified using experimental data by an eigensystem realization algorithm (ERA) and the placement of the two piezoelectric actuators and single sensor is determined using a finite element model (FEM) and an optimization procedure. A robust controller for active damping is designed using an LMI framework, and a reduced model with observation and control spillover effects is implemented using a computer. The simulation results demonstrate the efficacy of the approach, and show that the control system increases the damping in some of the modes.

O efeito da autocorrelação no planejamento das cartas de controle de x̄ e EWMA

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variable structure controller and observer applied to induction machine

This work will propose the control of an induction machine in field coordinates with imposed stator current based on theory of variable structure control and sliding mode. We describe the model of an induction machine in field coordinates with imposed stator current and we show the design of variable structure control and sliding mode to get a desirable dynamic performance of that plant. To estimate the inaccessible states we will use a state observer (estimator) based on field coordinates induction machine. We will present the results of simulations in any operation condition (start, speed reversal and load) and with parameters variation of the machine compared to a PI control scheme.

Desempenho dinâmico de um trator agrícola utilizando biodiesel destilado de óleo residual

The objective of this study was to evaluate the dynamic performance of an agricultural tractor utilizing distilled biodiesel (50% ethylic + 50% methylic) as a function of the proportion of biodiesel and diesel of petroleum (0 and 100%, 5 and 95%, 15 and 85%, 25 and 75%, 50 and 50%, 75 and 25% and 100 and 0%), respectively. This research was done in the area of the Department of Rural Engineering of the Paulista State University (UNESP), Jaboticabal Campus, SP, located in the latitude 21° 14′ 28″ S and longitude 48° 17′12″ W. A tractor 4 x 2 FWA was used, with a 73.6 kW (100 HP) motor and a ballast tractor. The biodiesel used was produced from spent oil from food frying. The experimental design was entirely randomized, with 7 treatments and 5 repetitions, totaling 35 observations. The results showed that the biodiesel and diesel blend significantly influenced the hourly volumetric consumption, hourly mass consumption, fuel consumption per worked area and specific fuel consumption variables. When the tractor operated with 100% of biodiesel (B100) the specific fuel consumption increased 18% on average in relation to diesel (B0).

Product mix: The approach of throughput per day

Defining product mix is very important for organisations because it determines how productive resources are allocated among various operations. However, it is often defined subjectively. The methods commonly used for this definition are Integer Linear Programming and heuristics based in Theory of Constraints, which use maximum throughput as a performance measure. Although this measure provides maximum throughput to specific problem, it does not consider aspects of time, as days, utilised to make the throughput. Taking this into account, the aim of this paper is to present a throughput per day approach to define product mix, as well as to propose a constructive heuristic to help in this process. The results show that the proposed heuristic obtained satisfactory approximation when compared to the optimum values obtained by enumeration. © 2013 Copyright Taylor and Francis Group, LLC.

Desenvolvimento de um aplicativo para processamento de dados e criação de um simulador computacional de uma transmissão para veículos

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Desenvolvimento e avaliação do desempenho de um equipamento para ensaio dinâmico de rodado agrícola individual

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Informação no âmbito empresarial: uma reflexão acerca dos modelos de gestão da informação

In the present context the information assumes a major role, providing to the business environment a dynamic performance that is constantly renewing and adapting itself to the environment in which it operates. In that sense we aimed, through literature, a reflection the models of information management for business. Were review the models of Beuren (2000), Choo (1997, 1999) and Davenport and Prusak (1998). We conclude that information management can provide a significant positive differential to business in the contemporary context.

Efeitos do fundo de desenvolvimento da educação básica e valorização dos profissionais da educação - FUNDEB na educação infantil de Medianeira - Paraná

Pós-graduação em Educação - FFC

Inclusão escolar com apoio: uma análise do serviço do ensino itinerante

We investigated the process of inclusion in the school common areas, tracking the performance of a traveling school teacher (teaching support service specialist), type of service in Special Education, as a support to the school's educational proposal. Objectives: To identify, describe and analyze the performance of itinerant school teacher in a school of mainstream school, with students and their teachers, to analyze the perception of two teachers of the common teaching about the process of integration of pupils with special educational needs in their classes; examine the roles and responsibilities of itinerant school teacher through an exploratory qualitative approach. Participants: an itinerant school teacher, two teachers and two of the common teaching students with special educational needs included in mainstream school. Observations were made weekly at the school over a period of six months, semi-structured interviews with teachers and document analysis. The results showed different facets of roaming at the intersection with the common teaching among them may be noted that acts as a parallel system in the common school, creating a gap between them which may compromise or disadvantage of the dynamic performance of service support, but this gap is overcome at critical times facing the mainstream school, where this service benefit the child's learning process and promotes their inclusive education policy.

Extensão do modelo hipercubo para análise de sistemas de atendimento médico emergencial com prioridade na fila

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

On the shock performance of a nonlinear vibration isolator with high-static-low-dynamic-stiffness

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimation and evaluation of dynamic properties as indicators of changes on soil structure in sugarcane fields of São Paulo State - Brazil

The indiscriminate management and use of soils without moisture control has changed the structure of it due to the increment of the traffic by agricultural machines through the years, causing in consequence, a soil compaction and yield reduction in the areas of intensive traffic. The purpose of this work was to estimate and to evaluate the performance of preconsolidation pressure of the soil and shear stress as indicators of changes on soil structure in fields cropped with sugarcane, as well as the impact of management processes in an Eutrorthox soil structure located in São Paulo State. The experimental field was located in Piracicaba's rural area (São Paulo State, Brazil) and has been cropped with sugarcane, in the second harvest cycle. The soil was classified by Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) [Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), 1999. Centro Nacional de Pesquisa de Solos. Sistema Brasileiro de Classificao de Solos, Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), Brasilia, 412 pp.] as an Eutrorthox. Undisturbed samples were collected and georeferenced in a grid of 60 m x 60 m from two depths: 0-0.10 m (superficial layer - SL) and in the layer of greatest mechanical resistance (LGMR), previously identified by cone index (CI). The investigated variables were pressure preconsolidation (sigma(p)), apparent cohesion (c) and internal friction angle (phi). The conclusions from the results were that the SLSC was predicted satisfactorily from up as a function of soil moisture; thus, decisions about machinery size and loading (contact pressures) can be taken. Apparent cohesion (c), internal friction angle (phi) and the Coulomb equation were significantly altered by traffic intensity. The sigma(p), c and phi maps were shown to be important tools to localize and visualize soil compaction and mechanical resistance zones. They constitute a valuable resource to evaluate the traffic impact in areas cropped with sugarcane in State of São Paulo, Brazil. (C) 2008 Elsevier B.V. All rights reserved.