Comparação de métodos baseados em algoritmos genéticos para ajuste coordenado de estabilizadores de sistemas de potência

Essa dissertação de mestrado apresenta um estudo comparativo entre três metodologias baseadas em algoritmos genéticos para ajuste coordenado de estabilizadores de sistemas de potência (ESP). Os procedimentos de ajuste do ESP são formulados como um problema de otimização, a fim de: 1) maximizar o coeficiente de amortecimento mínimo do sistema em malha fechada; 2) maximizar o somatório de todos os coeficientes de amortecimento do sistema em malha fechada; e 3) deslocar os modos eletromecânicos poucos amortecidos ou mal amortecidos para uma zona pré-escrita no plano s. As três metodologias consideram um conjunto de condições de operacionais pré-especificadas. O sistema elétrico foi representado por equações no espaço de estado e as matrizes associadas com a modelagem foram obtidas por meio da versão acadêmica do programa PacDyn. As simulações foram realizadas usando o MATLAB. As metodologias foram aplicadas no conhecido sistema teste New England.

Análise da robustez e aplicações de controle com modos deslizantes em sistemas incertos com atraso no controle

Pós-graduação em Engenharia Elétrica - FEIS

Regulação de tensão utilizando compensador série controlado a tiristores para sistemas de distribuição

Pós-graduação em Engenharia Elétrica - FEIS

Digital controller design considering hardware constraints: application in a paraplegic patient

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

Contribuição das redes de T.I. para formulação da estratégia e gestão das empresas

Pós-graduação em Engenharia de Produção - FEB

Controle de velocidade de um motor de indução trifásico usando técnicas de ajuste empírico para bancada de teste no laboratório de automação

This work aims to make the closed loop control of a three phase induction motor, through the integration of the following equipment: a frequency inverter, the actuator system; a programmable logic controller (PLC), the controller; an encoder, the velocity sensor, used as a feedback monitoring the control variable and the three-phase induction motor, the plant to be controlled. The control is performed using a Proportional - Integrative - Derivative (PID) approach. The PLC has a help instruction, which performs the auto adjustment of the controller, that instruction is used and confronted with other adjustment methods. There are several types of methods adjustments to the PID controllers, where the empirical methods are addressed in this work. The system is deployed at the Interface and Electro Electronic Control laboratory in the Universidade Estadual Paulista Júlio Mesquita Filho, Guaratinguetá, São Paulo, then, in the future, this work becomes an experiment to be conducted in the classroom, allowing undergraduate students to develop a greater affinity to the programs used by the PLC as well as studies of undergraduate and graduate works with the help of assembly made

Análise comparativa entre sistemas de resfriamento de injeção de plástico

This study aims to prove the economic feasibility of the installation of mechanical compression chillers on plastic injection molding machines in order to reduce the production cycle time of toothbrush cables in a specific case study. This evidence was confirmed by the comparative analysis of the system replaced and the new system installed. The old system had only one closed loop cooling tower which pumped chilled water to the injection molds, and the new system has the same tower sending cold water to the condensers of individual chillers installed on each injection machine. We conducted an analysis of energy efficiency in each system, showing that in terms of thermal efficiency virtually nothing has changed, but in terms of electricity demand the new system consumes 60.3 kW more. We conducted an analysis of machine productivity for both systems, showing a much higher productivity of the new system due to reduced cycle times caused by the presence of chillers and their greater cooling capacities. Equipped with data such as electricity rates, increases in operating costs and initial investments, the increase in consumption and demand of electricity plus the cycle time reduction were also calculated over so the simple payback 1 year and 2 months was reached

Controlador PID utilizando microcontrolador PIC

This monograph proposes the implementation of a low cost PID controller utilizing a PIC microcontroller, and its application in a positioning system previously controlled by a dedicated integrated circuit for a positioning system. Applying the closed-loop PID control, the system instability was reduced, and its response was smoother, eliminating vibrations and mechanical wear compared to its response with the dedicated integrated circuit, which has a very limited control action. The actuator of the system is a DC motor, whose speed is controlled by the Pulse Width Modulation (PWM) technique, using a Full-Bridge circuit, allowing the shift of direction of rotation. The utilized microcontroller was the PIC16F684, which has an enhanced PWM module, with its analog converters used as reference and position feedback. The positioning sensor is a multiturn potentiometer coupled to the motor axis by gears. The possibility of programming the PID coefficients in the microcontroller, as well as the adjustment of the sampling rate, allows the implemented system achieving high level of versatility

Uma análise das estratégias de manufatura adotadas por seis montadoras da indústria automobilística mundial

The Brazilian automotive industry has undergone profound changes during the 90’s decade, as a consequence of the market opening up through the liberation of automobile imports. The exposure of the Brazilian domestic market to competition with imported products of high quality and lower prices indicated the need for significant changes in those auto industries operating in this country, with the intention of making them competitive. To achieve these objectives management and production concepts were adopted, such as: the just-in-time philosophy; lean manufacturing; outsourcing; reengineering and increasing the rate of automation in both production and management systems. These changes helped to increase productivity and, in turn, reduced the level of employment in the sector, especially in activities where the required qualification levels were low. Despite this modernization, the Brazilian companies have committed themselves to meet the specific needs of the Brazilian market. The objective of this paper is to analyze and present manufacturing strategies from six manufacturers of automotive vehicles: Toyota in Japan, Fiat in Italy, Volkswagen in Brazil and Germany and General Motors in the U.S. and Brazil. The predominant method of research was from reviewing relevant literature, whereas the empirical data was analyzed qualitatively. The article seeks to identify the manufacturing strategies adopted by manufacturers located in the above countries, electing one automotive manufacturer to represent each country. The research demonstrated that the processes for production of automobiles in four plants located in, the U.S. (GM); Italy (Fiat); Japan (Toyota) and Germany (VW) are similar to those adopted in Brazilian industrial plants of the same companies (GM and VW), with differences of operations only in the business strategies adopted by each of them.

O engavetamento de modelos de ensino superior dentro da universidade pública

This paper explores the contradictions between models conflicting today in Brazilian universities. The conglomeration of isolated institutions, integrated and multifunctional university and university-enterprise, service provider. This last model attempts to integrate higher education institutions to supply chains dominated by capital. Public universities were designed to provide innovative services and train staff researchers for such activity. The training of skilled workforce would be fundamentally task of private universities. But in any case, the onus would be on this training students. This model has been driven from the 1990s, with "instruction manuals" of the World Bank, and in 2000, with the IMF recommendations and, in the case of Latin American universities, Fundación Universia, sponsored by the Santander Bank. The question remains: the university will be able to organize the productive forces which have around research goals and staff training for independent development.

As dimensões geográficas dos Arranjos Produtivos Locais

This article aims to further discuss the Local Productive Arrangements (APLs), considering some geographical visions thinking about spatial configuration and the economic and social processes that characterize them, configuring a wide range of territorialities and productive territories that mark the landscape current Brazilian. In this sense, APLs are present today in both the figure of those who study analytical concept for regional development, and as a public policy supporting networks and supply chains in their territorial bases, especially small businesses. Thus, this arrangements can be read, geographically, as territorial productive specializations that are configured in spatial circuits of production, integrated with other regions, localities and supply chains through the morphology of networks and districts and grounded in networks of urban networks of material and immaterial flows which are bringing urban centers of different sizes. Considering the multidimensionality of the subject, the clusters have certain weaknesses in terms of their assumptions and perspectives, especially the limitations of the tool if designed just for resources and policies applied at the local level. Suggest the approach of a "geography of APLs" is to seek treat it from a territorial and socio reading.

Projeto de controladores robustos para acionamento de um motor de indução trifásico

Pós-graduação em Engenharia Elétrica - FEIS

Co-simulation tools for networked control systems: revision and utilization

Networked control systems (NCSs) are distributed control systems in which the sensors, actuators, and controllers are physically separated and connected through an industrial network. The main challenge related to the development of NCSs is the degenerative effects caused by the inclusion of this communication network in the closed loop control. In order to mitigate these effects, co-simulation tools for NCS have been developed to study the network influence in the NCS. This paper presents a revision about co-simulation tools for NCS and the application of two of these tools for the design and evaluation of NCSs. The TrueTime and Jitterbug tools were used together to evaluate the main configuration parameter that affects the performance of CAN-based NCS and to verify the NCS quality of control under various timing conditions including different transmission period of messages and network delays. Therefore, the simulation results led to the conclusion that despite the transmission period of messages is the most significant factor among the analyzed in the design of NCS, its influence is related to the kind of system with greater effects in NCSs with fast dynamics.

Nonlinear ball and beam control system identification

The Ball and Beam system is a common didactical experiment in control laboratories that can be used to illustrate many different closed-loop control techniques. The plant itself is subjected to many nonlinear effects, which the most common comes from the relative motion between the ball and the beam. The modeling process normally uses the lagrangean formulation. However, many other nonlinear effects, such as non-viscous friction, beam flexibility, ball slip, actuator elasticity, collisions at the end of the beam, to name a few, are present. Besides that, the system is naturally unstable. In this work, we analyze a subset of these characteristics, in which the ball rolls with slipping and the friction force between the ball and the beam is non-viscous (Coulomb friction). Also, we consider collisions at the ends of the beam, the actuator consists of a (rubber made) belt attached at the free ends of the beam and connected to a DC motor. The model becomes, with those nonlinearities, a differential inclusion system. The elastic coefficients of the belt are experimentally identified, as well as the collision coefficients. The nonlinear behavior of the system is studied and a control strategy is proposed.

Há sinergia entre o sistema lean manufacturing e a gestão ambiental? mapeando o estado da arte

In recent decades, two research themes have been prominent in the academic and organizational setting: lean manufacturing and green management. Since 1996, when Florida (1996) wrote an article focusing on the synergy between these two areas, the debate if “Lean is Green?” enters in the academic field. It is in this context that this research presents the results of a systematic literature on the topic, focusing on the characteristics, positive and negative impacts, lean paradigms, green paradigms and design of supply chains. To perform this procedure it were followed the methodological footsteps of Lage Junior and Godinho Filho (2010). The research occurred in the database Scopus and it was conducted from June, 2012 to July, 2012.The key word used was “green lean” and as search filter it were included only articles and conference Papers. Their main result is a deep analysis of the accumulated knowledge on the subject, where it is revealed that the majority of studies point to the synergy between some components of the lean manufacturing system in relation to environmental management. The research gap found is related to articles that address the entropy of the union of lean and green systems.