Second moment constraints and the control problem of Markov jump linear systems

This paper addresses the optimal solution for the regulator control problem of Markov jump linear systems subject to second moment constraints. We can characterize and obtain the solution explicitly using linear matrix inequalities techniques. The constraints are imposed on the second moment of both the system state and control vector, and the optimal solution is obtained in a computable form. To illustrate the usefulness of the approach, specially that for systems subject to abrupt variations and physical limitations, we present an application for one joint of the European Robotic Arm

Restoration as art and pleasure in labour: professional qualification in worksites

A presente dissertação analisa a importância da transmissão oral e empírica do saber fazer dos artífices tradicionais para salvaguarda do Patrimônio Cultural edificado, estabelecendo assim uma crítica sobre as formas atuais de contratação de obras de restauração e sobre o distanciamento entre teoria e prática que se vê refletido nas políticas de preservação patrimonial no Brasil. Estas tendem a privilegiar a preservação da forma e do objeto arquitetônico por meio do instrumento do tombamento, deixando comumente as técnicas construtivas tradicionais à margem da discussão. Trata-se de uma contradição uma vez que para preservação do Patrimônio Cultural arquitetônico é imprescindível o domínio de técnicas construtivas já não mais correntemente aplicadas, baseadas fundamentalmente no trabalho manual e, dependendo, portanto, da destreza, habilidade e inventividade dos artesãos. Para contribuir na reflexão sobre como viabilizar a formação profissional do trabalhador dentro dos canteiros de obra de restauração no cenário brasileiro atual, são apresentados tipos distintos de experiências realizadas no âmbito público e privado, tendo como foco o Programa de Oficinas-Escola financiado e difundido na América Latina pela Agência Espanhola de Cooperação Internacional para o Desenvolvimento a partir da década de 1990. Este programa conjuga a preservação do patrimônio cultural com o resgate de ofícios tradicionais, a formação profissional e a geração de renda e trabalho, utilizando o método aprender fazendo, em que a aprendizagem se dá em situações reais de trabalho. A longa duração e o largo alcance territorial do programa possibilitaram a comparação de diferentes arranjos em diferentes realidades, confrontando-os com a experiência das três oficinas-escola brasileiras estabelecidas nas cidades de João Pessoa, Salvador e São Luís. Esta análise permitiu identificar entraves comuns e possíveis caminhos para centros de formação profissional no campo da restauração, que tenham como princípios a formação integral do ser humano e o adensamento do poder nas mãos de quem lida com o conhecimento técnico, valorizando e reconhecendo o seu saber.This dissertation analyzes the importance of the oral and empirical transmission of the knowhow of the traditional craftsmen to safeguard the built Cultural Heritage, thus establishing a critique about the current forms of hiring restoration works and about the distance between theory and practice that is reflected in heritage preservation policies in Brazil. These tend to privilege the preservation of the architectural form and object through the instrument entitled tombamento, commonly leaving the traditional constructive techniques out of the discussion. This is a contradiction since the preservation of the architectural cultural heritage requires the mastery of constructive techniques no longer commonly applied, based fundamentally on manual work and, therefore, depending on the craftsmens skill and inventiveness. To contribute to the debate on how to estabilish the professional qualification of workers within restoration sites in the current Brazilian scenario, different types of experiences carried out in the public and private context are presented, focusing on the Escuelas Taller Program funded and disseminated in Latin America by the Spanish Agency for International Cooperation for Development from the 1990s. This program combines the preservation of cultural heritage with the rescue of traditional crafts, professional capacitation and the generation of income and work, using the learn by doing method, in which learning takes place in real work situations. The long duration and wide territorial reach of the program made it possible to compare different arrangements in different realities, comparing them with the experience of the three Brazilian school workshops established in the cities of João Pessoa, Salvador and São Luís. This analysis allowed us to identify common barriers and possible paths for professional qualification centers in restoration, having as principles the integral formation of the human being and the concentration of power in the hands of those who deal with technical knowledge, valuing and recognizing it

Constrained control problem within a finite horizon of markovian jump discrete linear systems

Orientador: João Bosco Ribeiro do ValDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de ComputaçãoResumo: O objetivo deste trabalho é propor e resolver o problema de controle em horizonte finito com restrições de Sistemas Lineares Discretos com Saltos Markovianos (SLDSM) na presença de ruído. As restrições dos vetores de estado e de controle não são rígidas e são estabelecidas por valores limites dos seus respectivos primeiro e segundo momentos. O controlador baseia-se numa estrutura de realimentação linear de estados, devendo minimizar uma função custo quadrática. Consideram-se duas situações com respeito à informação disponível da cadeia de Markov associada: num primeiro caso o estado da cadeia de Markov é conhecido em cada instante e num segundo caso dispõe-se apenas de sua distribuição probabilística inicial. Uma formulação determinística do problema estocástico é desenvolvida de modo que as condições necessárias de otimalidade propostas e as restrições possam ser facilmente incluídas utilizando-se desigualdades matriciais lineares (do inglês, Linear Matrix Inequalities - LMI). A inclusão de restrições constitui a principal contribuição, uma vez que elas são pertinentes a vários campos de aplicação tais como indústria química, transporte de massa, economia, etc. Para ilustração do método são apresentadas duas aplicações: uma referente à regulação de tráfego em linhas metroviárias e outra referente ao problema de seleção de ativos de portfólios em aplicações financeirasAbstract: The purpose of this work is to propose and solve the constrained control problem within a finite horizon of Markovian Jump Discrete Linear Systems (MJDLS) driven by noise. The constraints of the state and control vectors are not rigid and limits are established respectively to their first and second moments. The controller is based on a linear state feedback structure and shall minimize a quadratic cost function. Two cases regarding the available information of the Markovian chain states are considered: firstly the Markov chain states are known at each step and secondly only its initial probability distribution is available. A deterministic formulation to the stochastic problem is developped in order that the proposed necessary optimality conditions and the constraints are easily included by using Linear Matrix Inequalities (LMI). The constraints consideration constitutes the main contribution, since they are pertinent to several application fields as for example chemical industry, mass transportation, economy etc. Two applications are presented for ilustration: one refers to metro lines traffic regulation and another refers to the financial investment income controlMestradoAutomaçãoMestre em Engenharia Elétric

A auto-ajuda como interdiscursividade em O alquimista de Paulo Coelho

This work, entitled The Self-Help as Interdiscursivity in The Alchemist by Paulo Coelho , has as a goal to establish how the self-help speech crosses interdiscoursively the corpus in analyses as an aesthetical asset/value to the construction of the literary discourse. To develop this study, the readings were based on concepts of the Discourse Analysis theory of the French school such as Interdiscourse, Discoursive Memory and Constitutive Discourse. Furthermore, support was found in the bakhtinian philosophy of language to understand Dialogism. The discoursive analysis of The Alchemist tries to detect how the self-help discourse crosses interdiscoursively the novel and the aesthetical effects built by this same discourse. It can be seen that the self-help discourse grounds the narrative events. Every time Santiago the young pastor weakens in the pursuit of the treasure seen in his recurrent dream, self-help statements are re-stated through the voices of other characters. Those characters are embodied with wisdom and the knowledge Santiago needs to start his journey towards personal fulfillment. Here, the self-help discourse uses constitutive discourses, including its own literary discourse, to be built. Therefore, the literary discourse being analyzed in this work is crossed for several other discourses, such as religious and economical-capitalist ones. When making up stories that create heroes who face same problems as regular human beings, Paulo Coelho stays away from what Russian formalists understand as being good literature . And that is what causes literary critics to consider the Brazilian author as a poor writer/novelist. However, by making his heroes suffer the same males as the ones suffered by the contemporary man, Paulo Coelho attracts the attention of the reader. He or she identifies with the hero feeling insecure, lacking self-confidence, boredom, long for self-fulfillment generated by historic, social and economical events that describe the contemporary world. Paulo Coelho uses the self-help discourse to build his hero because this is what helps the modern man in the search for identity.Mestre em Estudos LinguísticosEsta pesquisa, intitulada A Autoajuda como Interdiscursividade em O Alquimista de Paulo Coelho , tem por objetivo estabelecer de que forma o discurso de autoajuda atravessa interdiscursivamente o corpus em análise, caracterizando-se como valor estético de construção do discurso literário. Para desenvolver tal análise, balizamos nossas leituras nos conceitos desenvolvidos pela Análise do discurso de linha francesa, doravante AD, no que concerne a noções como Interdiscurso, Memória Discursiva e Discurso Constituinte. Além disso, buscamos apoio na filosofia da linguagem bakhtiniana para entender a noção de Dialogismo. A análise discursiva do romance O Alquimista busca identificar de que forma o discurso de autoajuda atravessa interdiscursivamente a obra e os efeitos estéticos que esse discurso constrói. Podemos dizer que o discurso de autoajuda baliza os acontecimentos narrativos, pois sempre que Santiago, um jovem pastor que teve um sonho repetido, esmorece na busca pelo tesouro que viu em seu sonho, enunciados que constituem o discurso de autoajuda são retomados na voz de outras personagens que, por sua experiência de vida e conhecimentos adquiridos, são detentoras dos saberes de que Santiago necessita para empreender sua jornada em busca da realização pessoal. O discurso de autoajuda se vale de discursos constituintes, inclusive do próprio discurso literário, para sua construção. Percebemos, então, que o discurso literário em análise é atravessado por diversos outros discursos, como o discurso religioso e o discurso econômico-capitalista. Ao criar histórias que retratam heróis que enfrentam as mesmas dificuldades que os seres humanos, Paulo Coelho afasta-se do que os formalistas russos entendem por boa literatura . Isso faz com que Paulo Coelho não seja bem visto pelos críticos de literatura. No entanto, ao criar heróis que vivem as mesmas mazelas do homem contemporâneo, Paulo Coelho capta a atenção do leitor, pois este se identifica com o herói, ao ver que os problemas enfrentados por ambos são os mesmos: insegurança, falta de confiança em si mesmo, marasmo, vontade de realização pessoal, tudo isso gerado por diversos acontecimentos históricos, sociais e econômicos que caracterizam o mundo contemporâneo. Paulo Coelho vale-se do discurso de autoajuda, que é o discurso que auxilia o homem contemporâneo na busca de sua identidade, para balizar as ações de seu herói

Restoration as art and pleasure in labour: professional qualification in worksites

A presente dissertação analisa a importância da transmissão oral e empírica do saber fazer dos artífices tradicionais para salvaguarda do Patrimônio Cultural edificado, estabelecendo assim uma crítica sobre as formas atuais de contratação de obras de restauração e sobre o distanciamento entre teoria e prática que se vê refletido nas políticas de preservação patrimonial no Brasil. Estas tendem a privilegiar a preservação da forma e do objeto arquitetônico por meio do instrumento do tombamento, deixando comumente as técnicas construtivas tradicionais à margem da discussão. Trata-se de uma contradição uma vez que para preservação do Patrimônio Cultural arquitetônico é imprescindível o domínio de técnicas construtivas já não mais correntemente aplicadas, baseadas fundamentalmente no trabalho manual e, dependendo, portanto, da destreza, habilidade e inventividade dos artesãos. Para contribuir na reflexão sobre como viabilizar a formação profissional do trabalhador dentro dos canteiros de obra de restauração no cenário brasileiro atual, são apresentados tipos distintos de experiências realizadas no âmbito público e privado, tendo como foco o Programa de Oficinas-Escola financiado e difundido na América Latina pela Agência Espanhola de Cooperação Internacional para o Desenvolvimento a partir da década de 1990. Este programa conjuga a preservação do patrimônio cultural com o resgate de ofícios tradicionais, a formação profissional e a geração de renda e trabalho, utilizando o método aprender fazendo, em que a aprendizagem se dá em situações reais de trabalho. A longa duração e o largo alcance territorial do programa possibilitaram a comparação de diferentes arranjos em diferentes realidades, confrontando-os com a experiência das três oficinas-escola brasileiras estabelecidas nas cidades de João Pessoa, Salvador e São Luís. Esta análise permitiu identificar entraves comuns e possíveis caminhos para centros de formação profissional no campo da restauração, que tenham como princípios a formação integral do ser humano e o adensamento do poder nas mãos de quem lida com o conhecimento técnico, valorizando e reconhecendo o seu saber.This dissertation analyzes the importance of the oral and empirical transmission of the knowhow of the traditional craftsmen to safeguard the built Cultural Heritage, thus establishing a critique about the current forms of hiring restoration works and about the distance between theory and practice that is reflected in heritage preservation policies in Brazil. These tend to privilege the preservation of the architectural form and object through the instrument entitled tombamento, commonly leaving the traditional constructive techniques out of the discussion. This is a contradiction since the preservation of the architectural cultural heritage requires the mastery of constructive techniques no longer commonly applied, based fundamentally on manual work and, therefore, depending on the craftsmens skill and inventiveness. To contribute to the debate on how to estabilish the professional qualification of workers within restoration sites in the current Brazilian scenario, different types of experiences carried out in the public and private context are presented, focusing on the Escuelas Taller Program funded and disseminated in Latin America by the Spanish Agency for International Cooperation for Development from the 1990s. This program combines the preservation of cultural heritage with the rescue of traditional crafts, professional capacitation and the generation of income and work, using the learn by doing method, in which learning takes place in real work situations. The long duration and wide territorial reach of the program made it possible to compare different arrangements in different realities, comparing them with the experience of the three Brazilian school workshops established in the cities of João Pessoa, Salvador and São Luís. This analysis allowed us to identify common barriers and possible paths for professional qualification centers in restoration, having as principles the integral formation of the human being and the concentration of power in the hands of those who deal with technical knowledge, valuing and recognizing it

Constrained Model Predictive Control Of Jump Linear Systems With Noise And Non-observed Markov State

This paper presents a variational method to the solution of the model predictive control (MPC) of discrete-time Markov jump linear systems (MJLS) subject to noisy inputs and a quadratic performance index. Constraints appear on system state and input control variables in terms of the first two moments of the processes. The information available to the controller does not involve observations of the Markov chain state and, to solve the problem a sequence of linear feedback gains that is independent of the Markov state is adopted. The necessary conditions of optimality are provided by an equivalent deterministic form of expressing the stochastic MPC control problem subject to the constraints. A numerical solution that attains the necessary conditions for optimality and provides the feedback gain sequence is proposed. The solution is sought by an iterative method performing a variational search using a LMI formulation that takes the state and input constraints into account. © 2006 IEEE.2006929934Costa, O.L.V., Fragoso, M.D., Marques, R.P., (2005) Discrete-Time Markovian Jump Linear Systems, , New York: Springer-VerlagCosta, O.L.V., Fragoso, M.D., Stability results for discrete-time linear systems with Markovian jumping parameters (1993) Journal of Mathematical Analysis and Aplications, 179, pp. 154-178Costa, O.L.V., Fragoso, M.D., Discrete-time LQ-optimal control problems for finite Markov jump parameters systems (1995) IEEE Transactions on Automatic Control, 40, pp. 2076-2088Ji, Y., Chizeck, H.J., Controllability, stabilizability and continuous-time Markovian jump linear quadratic control (1990) IEEE Transactions on Automatic Control, 35 (7), pp. 777-788Ji, Y., Chizeck, H.J., Jump linear quadratic Gaussian control: Steady-state solution and testable conditions (1990) Control-Theory and Advanced Technology, 6 (3), pp. 289-319. , SeptemberMaciejowski, J.M., (2001) Predictive Control with constraints, , Pearson Education LimitedBitmead, R.R., Gevers, M., Wertz, V., (1990) Adaptive Optimal Control: The thinking man's GPC, , Prentice HallMayne, D.Q., Rawlings, J.B., Rao, C.V., Scokaert, P.O.M., (2000) Constrained model predictive control: Stability and optimality, 36 (6), pp. 789-814Costa, O.L.V., Assumpção, E.O., Discrete-time constrained quadratic control of Markovian jump linear systems (1996) 35th IEEE Conference on Decision and Control, pp. 1763-1764. , Kobe, JapanCosta, O.L.V., Assumpção, E.O., Boukas, E.K., Marques, R.P., Constrained quadratic state feedback control for discrete-time Markovian jump linear systems (1999) Automatica, 35 (4), pp. 617-626Vargas, A.N., do Val, J.B.R., Costa, E.F., Receding horizon control of Markov jump linear systems subject to noise and unobservable state chain (2004) 43th IEEE Conference on Decision and Control, pp. 4381-4386. , Paradise Island, The BahamasBoyd, S., Ghaoui, L.E., Feron, E., Balakrishnan, V., (1994) Linear Matrix Inequalities in System and Control Theory, , SIAMVanAntwerp, J.G., Braatz, R.D., A tutorial on linear and bilinear matrix inequalities (2000) Journal of Process Control, (10), pp. 363-385Geromel, J.C., Peres, P.L.D., Souza, S.R., 2- guaranteed cost control for uncertain discrete-time linear systems (1993) Int. Journal of Control, 57, pp. 853-864Sturm, J.F., Using SeDuMi, a Matlab Toolbox for optimization over symmetric cones (1999) Optimization Methods and Software, 11-12, pp. 625-653Peaucelle, D., Henrion, D., Labit, Y., Users guide for SeDuMi interface 1.04, , http://www.laas.fr/~peaucell/ software/SeDuMiInt.html, Online, Availabl

Analysis of semi-solid diecasting runner-gate system as a function of solid fraction

The injection of alloys in the semisolid state, is highly effective in reducing casting porosity, particularly the one due to turbulences during die filling. On the other hand, the use of semisolid billet poses additional difficulties about either proper alloy re-heating and die design, especially runner and gate system. Obviously gates must be thicker than in traditional diecasting, because of the higher alloy viscosity, however no standards for a good die design are today available in the literature and each manufacturer refers to his own experience and know-how. The aim of this work is to evaluate the effect of the various runner and gate geometrical parameters on the filling pattern, taking also into account the influence of different solid fractions, not only those related to not properly controlled re-heating temperature, but also those typical of rheocasting technology. The study was carried out by means of a numerical simulation commercial software (Procast), considering a typical aluminun-silicon alloy (A356), whose thermo-fluid dynamics properties needed for simulation are mostly available. The results obtained will be subsequently used for the fabrication of an experimental die, for the production of dumb bell and toughness specimens, for future tests in the University diecasting laboratory

Design and production of new aluminum thixotropic alloys for the manufacture of structural components by semisolid die casting

Semi-solid processing is nowadays a powerful technology for the realization of structural components; in addition to the increase in their mechanical properties, due to the globular structure instead of the dendritic one, further developments are most likely to be expected from alloy chemical composition adjustments in order to achieve higher performances compared with the industrially used A356 and A357. Aim of this research is to try to set up new aluminium. alloys for semisolid foundry applications, starting from the standard Al-Si system, at the base of all known casting processes. Different chemical compositions, based on either foundry or wrought Al alloys, have been investigated by means of computational thermodynamics (Pandat (R)), producing quantitative data about solidus-liquidus interval, solid fraction as a function of temperature, phase diagrams i.e. potential for age hardening, etc.. Some selected alloys, fitting the needs of good castability, proper concentration of hardening elements in the alpha phase and, obviously, easy production of feedstock material have been mechanically stirred by means of an experimental apparatus designed and self-constructed in the foundry laboratory of the university; the effect of different stirring tool configurations on the semi-solid state obtainment has also been assessed. Subsequently, the manufactured alloys have been reheated and cast into a simple die, properly designed, for the production of small samples. Microstructural investigations have been done on the stirred alloy (before and after re-heating), on the as cast and the heat treated samples to evaluate the efficiency of the designed system and of the defined alloys. Experimental tests on the processed alloys have been carried out by means of an instrumented crucible in order to verify the predicted thermodynamic properties supplied by simulation study (i.e. fs-temperature curve)