Projetos de controladores para sistemas de potência utilizando LMI'S

A presente dissertação tem como objetivo estudar e aprimorar métodos de projetos de controladores para sistemas de potência, sendo que esse trabalho trata da estabilidade dinâmica de sistemas de potência e, portanto, do projeto de controladores amortecedores de oscilações eletromecânicas para esses sistemas. A escolha dos métodos aqui estudados foi orientada pelos requisitos que um estabilizador de sistemas de potência (ESP) deve ter, que são robustez, descentralização e coordenação. Sendo que alguns deles tiveram suas características aprimoradas para atender a esses requisitos. A abordagem dos métodos estudados foi restringida à análise no domínio tempo, pois a abordagem temporal facilita a modelagem das incertezas paramétricas, para atender ao requisito da robustez, e também permite a formulação do controle descentralizado de maneira simples. Além disso, a abordagem temporal permite a formulação do problema de projeto utilizando desigualdades matriciais lineares (LMI’s), as quais possuem como vantagem o fato do conjunto solução ser sempre convexo e a existência de algoritmos eficientes para o cálculo de sua solução. De fato, existem diversos pacotes computacionais desenvolvidos no mercado para o cálculo da solução de um problema de inequações matriciais lineares. Por esse motivo, os métodos de projeto para controladores de saída buscam sempre colocar o problema na forma de LMI’s, tendo em vista que ela garante a obtenção de solução, caso essa solução exista.

Moral hazard and nonlinear pricing in a general equilibrium model

The paper analyzes a two period general equilibrium model with individual risk and moral hazard. Each household faces two individual states of nature in the second period. These states solely differ in the household's vector of initial endowments, which is strictly larger in the first state (good state) than in the second state (bad state). In the first period households choose a non-observable action. Higher leveis of action give higher probability of the good state of nature to occur, but lower leveIs of utility. Households have access to an insurance market that allows transfer of income across states of oature. I consider two models of financiaI markets, the price-taking behavior model and the nonlínear pricing modelo In the price-taking behavior model suppliers of insurance have a belief about each household's actíon and take asset prices as given. A variation of standard arguments shows the existence of a rational expectations equilibrium. For a generic set of economies every equilibrium is constraíned sub-optímal: there are commodity prices and a reallocation of financiaI assets satisfying the first period budget constraint such that, at each household's optimal choice given those prices and asset reallocation, markets clear and every household's welfare improves. In the nonlinear pricing model suppliers of insurance behave strategically offering nonlinear pricing contracts to the households. I provide sufficient conditions for the existence of equilibrium and investigate the optimality properties of the modeI. If there is a single commodity then every equilibrium is constrained optimaI. Ir there is more than one commodity, then for a generic set of economies every equilibrium is constrained sub-optimaI.

Generalists versus specialists in organizations

In this paper, we discuss the trade-o¤ between specialization and coordination in an organizational design problem. Most papers on the assignment of heterogeneous managers to di¤erent hierarchic levels emphasize the role of talent: better managers should be on top of hierarchies. However, this requires talent to be measured on an one-dimensional scale. In this paper, we explore the implications of allowing talent to have two dimensions: breadth and depth. Specialists have deep knowledge of few areas while generalists have narrow knowledge of many areas. When perfect communication is impossible, hierarchies arise in which generalists are at the top and specialists are at the bottom. We propose a model of imperfect communication and discuss its implications for organizational design, the optimal degree of centralization and the depth of hierarchies. We show that our model also implies plausible organizational structures, like balanced hierarchies and pyramidal structures.

Decision rules and information provision : monitoring vs manipulation

We analyze the contractual design problem of a principal who delegates decision-making and information provision. The principal faces two tasks: he has to decide the level of discretion to be granted to the decision-maker and to establish who is in charge of supplying the information. We show that these two choices are intrinsically related. When the decision-maker is granted high discretion, information provision is optimally delegated to the parties directly affected by the decision. Conversely, when the decision-maker enjoys little discretion, it is more desirable to rely on a third impartial agent. The paper helps rationalize some organizational arrangements that are commonly observed in the context of judicial and antitrust decision-making.

Coordination in brazilian pharmaceutical supply chains

Supply chain coordination (SCC) can be a challenge for many organizations as different firms in the same chain has different expectations and interdependencies (Arshinder & Deshmukh, 2008). Lack of SCC can result in the bullwhip effect and poor performance for a firm and its partners. By investigating the phenomenon in the Brazilian pharmaceutical supply chain using a qualitative research, this paper aims to understand the main issues that avoid a better integrated chain. Results of 21 interviews suggested that the lack of coordination in this environment was influenced by the network design and the history of the sector in Brazil, as well as scarce resources

Dos direitos da personalidade e a lei de doação de órgãos: o que há para cartografar?

This study aimed at examining the representation and the level of knowledge as well as getting acquainted whether there had been significant divergence among three social groups of 3rd year Law students, 7th period Medical students at UFPB and a group of people from the Catholic Church in vila dos pescadores in João Pessoa - about organ donation, transplant law and ethical issues that raise questions. In order to accomplish the qualitative analysis, Bardin´s content analysis technique was applied in conjunction with the Chisquare test which was applied with significance level of 5% to quantitative data. The data revealed that most informants agree with organ donation, Although they are not acquainted with the law of transplants, and with the lack of confidence in the single list of recipients. The problem is that there is an encouragement to trades with organs and the possibility of any person legally authorized to donate organs in life. The statistically significant difference was observed in only two questions, ie, in response to the confidence in the diagnosis of brain death: 64% of 7th period Medical students at UFPB trust this diagnosis versus 12% of the evangelizing group of vila dos pescadores. The other difference refers to the answer about the confidence in the single list of recipients: 36% of the 7th period Medical students of UFPB said to trust the list versus 12% of the 3rd law students of UFPB. This is was a multidisciplinary study with Involvement of lawyers and doctors

Análise dos efeitos de um plano educacional individualizado no desenvolvimento acadêmico e funcional de um aluno com transtorno do espectro do autismo

Given the paradigm of inclusive education, the presence of students with autism spectrum disorder in regular schools has become more significant in recent years. Studies have revealed, however, deficits in academic participation of these students in these settings. Among the factors contributing to this phenomenon include poor teacher training and the lack of strategies to promote curriculum access. The aim of this study was to develop an instrument that would promote academic inclusion of a student with autism through procedures that could simultaneously empower the teacher. In this perspective, the study aimed to analyze the effects of an Individualized Educational Plan (IEP), developed collaboratively with teachers, on the academic and functional development of a student with autism in an early childhood education setting. Data were collected in a private school located in the city of Natal in Rio Grande do Norte, in the course of the academic year 2012. In addition to the student with autism, one teacher, a specialized educator, and four teacher aides participated in the study. The research used a single subject quasi-experimental design (AB) as well as qualitative methods of data analysis. The study was conducted in three phases: characterization, baseline and intervention. The first comprised interviews with the child´s parents and teachers, as well as the identification of two routines focus of intervention. In the second phase, the amount of time the student spent engaged in the selected routines during baseline was analyzed. In the third phase, the researcher prepared, collaboratively with the teachers, an individualized educational plan (IEP) for the student. Finally, the IEP was implemented by the teachers. The results indicated qualitative and quantitative changes in student´s participation in academic and functional tasks after the intervention program

Uma contribuição crítica para o redesenho de cadeiras de rodas adaptadas para crianças e adolescentes com paralisia cerebral

This work was aimed at making a critical analysis of the product wheelchair, both for using four different models, which were objects of study of the dissertation of Cláudia Regina Cabral Galvão, entitled Critical Analysis of the Mobility Products Seated a wheelchair - Used by Children and Adolescents with Cerebral Palsy in Natal / RN and other municipalities of Rio Grande do Norte . This product is considered an instrument in the social rehabilitation of great importance for people with physical disabilities. This study aims to position the issue and develop comments on technical up grading of certain models according to the needs of the user. Describes features of four models in search searched through catalogs in order to know its advantages and disadvantages of use. Were presented the definitions of ergonomics and ergonomic aspects to be considered on a design, the study of anthropometry and its recommendations. Discussions the methodology of project design in two parts: the first, on the structuring of design problem (formulation, analysis, synthesis and evaluation.) And the second on the project (design and development, implementation and evaluation and solution). With that review will include the possibilities for a new redesign of the wheelchair, based on forms of adaptation in order to achieve the target that was compressed by the average population studied. Seeks to that this project makes an improvement in quality of life of people in wheelchairs by including these people in society but also the improvement of rehabilitation

Classificação de imagens de ambientes coralinos: uma abordagem empregando uma combinação de classificadores e máquina de vetor de suporte

The use of the maps obtained from remote sensing orbital images submitted to digital processing became fundamental to optimize conservation and monitoring actions of the coral reefs. However, the accuracy reached in the mapping of submerged areas is limited by variation of the water column that degrades the signal received by the orbital sensor and introduces errors in the final result of the classification. The limited capacity of the traditional methods based on conventional statistical techniques to solve the problems related to the inter-classes took the search of alternative strategies in the area of the Computational Intelligence. In this work an ensemble classifiers was built based on the combination of Support Vector Machines and Minimum Distance Classifier with the objective of classifying remotely sensed images of coral reefs ecosystem. The system is composed by three stages, through which the progressive refinement of the classification process happens. The patterns that received an ambiguous classification in a certain stage of the process were revalued in the subsequent stage. The prediction non ambiguous for all the data happened through the reduction or elimination of the false positive. The images were classified into five bottom-types: deep water; under-water corals; inter-tidal corals; algal and sandy bottom. The highest overall accuracy (89%) was obtained from SVM with polynomial kernel. The accuracy of the classified image was compared through the use of error matrix to the results obtained by the application of other classification methods based on a single classifier (neural network and the k-means algorithm). In the final, the comparison of results achieved demonstrated the potential of the ensemble classifiers as a tool of classification of images from submerged areas subject to the noise caused by atmospheric effects and the water column

Sistema Híbrido de Inferência Baseado em Análise de Componentes Principais e Redes Neurais Artificiais Aplicado a Plantas de Processamento de Gás Natural

Nowadays, where the market competition requires products with better quality and a constant search for cost savings and a better use of raw materials, the research for more efficient control strategies becomes vital. In Natural Gas Processin Units (NGPUs), as in the most chemical processes, the quality control is accomplished through their products composition. However, the chemical composition analysis has a long measurement time, even when performed by instruments such as gas chromatographs. This fact hinders the development of control strategies to provide a better process yield. The natural gas processing is one of the most important activities in the petroleum industry. The main economic product of a NGPU is the liquefied petroleum gas (LPG). The LPG is ideally composed by propane and butane, however, in practice, its composition has some contaminants, such as ethane and pentane. In this work is proposed an inferential system using neural networks to estimate the ethane and pentane mole fractions in LPG and the propane mole fraction in residual gas. The goal is to provide the values of these estimated variables in every minute using a single multilayer neural network, making it possibly to apply inferential control techniques in order to monitor the LPG quality and to reduce the propane loss in the process. To develop this work a NGPU was simulated in HYSYS R software, composed by two distillation collumns: deethanizer and debutanizer. The inference is performed through the process variables of the PID controllers present in the instrumentation of these columns. To reduce the complexity of the inferential neural network is used the statistical technique of principal component analysis to decrease the number of network inputs, thus forming a hybrid inferential system. It is also proposed in this work a simple strategy to correct the inferential system in real-time, based on measurements of the chromatographs which may exist in process under study

Otimização de forma aplicando B-splines sob critério integral de tensões

This work proposes a computational methodology to solve problems of optimization in structural design. The application develops, implements and integrates methods for structural analysis, geometric modeling, design sensitivity analysis and optimization. So, the optimum design problem is particularized for plane stress case, with the objective to minimize the structural mass subject to a stress criterion. Notice that, these constraints must be evaluated at a series of discrete points, whose distribution should be dense enough in order to minimize the chance of any significant constraint violation between specified points. Therefore, the local stress constraints are transformed into a global stress measure reducing the computational cost in deriving the optimal shape design. The problem is approximated by Finite Element Method using Lagrangian triangular elements with six nodes, and use a automatic mesh generation with a mesh quality criterion of geometric element. The geometric modeling, i.e., the contour is defined by parametric curves of type B-splines, these curves hold suitable characteristics to implement the Shape Optimization Method, that uses the key points like design variables to determine the solution of minimum problem. A reliable tool for design sensitivity analysis is a prerequisite for performing interactive structural design, synthesis and optimization. General expressions for design sensitivity analysis are derived with respect to key points of B-splines. The method of design sensitivity analysis used is the adjoin approach and the analytical method. The formulation of the optimization problem applies the Augmented Lagrangian Method, which convert an optimization problem constrained problem in an unconstrained. The solution of the Augmented Lagrangian function is achieved by determining the analysis of sensitivity. Therefore, the optimization problem reduces to the solution of a sequence of problems with lateral limits constraints, which is solved by the Memoryless Quasi-Newton Method It is demonstrated by several examples that this new approach of analytical design sensitivity analysis of integrated shape design optimization with a global stress criterion purpose is computationally efficient

Algoritmos evolutivos dedicados à reconfiguração de redes radiais de distribuição sob demandas fixas e variáveis: estudo dos operadores genéticos e parâmetros de controle

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

Calculating the Best Dual Bound for Problems with Multiple Lagrangian Relaxations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Branch and bound algorithm for transmission system expansion planning using a transportation model

A method for optimal transmission network expansion planning is presented. The transmission network is modelled as a transportation network. The problem is solved using hierarchical Benders decomposition in which the problem is decomposed into master and slave subproblems. The master subproblem models the investment decisions and is solved using a branch-and-bound algorithm. The slave subproblem models the network operation and is solved using a specialised linear program. Several alternative implementations of the branch-and-bound algorithm have been rested. Special characteristics of the transmission expansion problem have been taken into consideration in these implementations. The methods have been tested on various test systems available in the literature.

Pattern recognition theory in nonlinear signal processing

A body of research has developed within the context of nonlinear signal and image processing that deals with the automatic, statistical design of digital window-based filters. Based on pairs of ideal and observed signals, a filter is designed in an effort to minimize the error between the ideal and filtered signals. The goodness of an optimal filter depends on the relation between the ideal and observed signals, but the goodness of a designed filter also depends on the amount of sample data from which it is designed. In order to lessen the design cost, a filter is often chosen from a given class of filters, thereby constraining the optimization and increasing the error of the optimal filter. To a great extent, the problem of filter design concerns striking the correct balance between the degree of constraint and the design cost. From a different perspective and in a different context, the problem of constraint versus sample size has been a major focus of study within the theory of pattern recognition. This paper discusses the design problem for nonlinear signal processing, shows how the issue naturally transitions into pattern recognition, and then provides a review of salient related pattern-recognition theory. In particular, it discusses classification rules, constrained classification, the Vapnik-Chervonenkis theory, and implications of that theory for morphological classifiers and neural networks. The paper closes by discussing some design approaches developed for nonlinear signal processing, and how the nature of these naturally lead to a decomposition of the error of a designed filter into a sum of the following components: the Bayes error of the unconstrained optimal filter, the cost of constraint, the cost of reducing complexity by compressing the original signal distribution, the design cost, and the contribution of prior knowledge to a decrease in the error. The main purpose of the paper is to present fundamental principles of pattern recognition theory within the framework of active research in nonlinear signal processing.