This thesis provides an analytical and two numerical methods for solving a parabolic equation of two-dimensional mean curvature flow with some applications. In analytical method, this equation is solved by Lie group analysis method, and in numerical method, two algorithms are implemented in MATLAB for solving this equation. A geometric algorithm and a step-wise algorithm; both are based on a deterministic game theoretic representation for parabolic partial differential equations, originally proposed in the genial work of Kohn-Serfaty [1]. / +46-767165881

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Markov decision processes (MDPs) are a general framework used by Artificial Intelligence (AI) researchers to model decision theoretic planning problems. Solving real world MDPs has been a major and challenging research topic in the AI literature. This paper discusses two main groups of approaches in solving MDPs. The first group of approaches combines the strategies of heuristic search and dynamic programming to expedite the convergence process. The second makes use of graphical structures in MDPs to decrease the effort of classic dynamic programming algorithms. Two new algorithms proposed by the author, MBLAO* and TVI, are described here.

We present tools for a network topology based characterization of heterogeneity in multiagent systems, thereby providing a framework for the analysis and design of heterogeneous multiagent networks from a network structure view-point. In heterogeneous networks, agents with a diverse set of resources coordinate with each other. Coordination among different agents and the structure of the underlying network topology have significant impacts on the overall behavior and functionality of the system. Using constructs from graph theory, a qualitative as well as a quantitative analysis is performed to examine an inter-relationship between the network topology and the distribution of agents with various capabilities in heterogeneous networks. Our goal is to allow agents maximally exploit heterogeneous resources available within the network through local interactions, thus exploring a promise heterogeneous networks hold to accomplish complicated tasks by leveraging upon the assorted capabilities of agents. For a reliable operations of such systems, the issue of security against intrusions and malicious agents is also addressed. We provide a scheme to secure a network against a sequence of intruder attacks through a set of heterogeneous guards. Moreover, robustness of networked systems against noise corruption and structural changes in the underlying network topology is also examined.

Specifications are necessary for communicating decisions and intentions and for documenting results at many stages of the program development process. Informal specifications are typically used today, but they are imprecise and often ambiguous. Formal specifications are precise and exact but are more difficult to write and understand. We present work aimed toward enabling the practical use of formal specifications in program development, concentrating on the Clear language for structured algebraic specification. Two different but equivalent denotational semantics for Clear are given. One is a version of a semantics due to Burstall and Goguen with a few corrections, in which the category-theoretic notion of a colimit is used to define Clear's structuring operations independently of the underlying 'institution' (logical formalism). The other semantics defines the same operations by means of straightforward set-theoretic constructions; it is not institutionindependent but it can be modified to handle all institutions of apparent interest. Both versions of the semantics have been implemented. The settheoretic implementation is by far the more useful of the two, and includes a parser and typechecker. An implementation is useful for detecting syntax and type errors in specifications, and can be used as a front end for systems which manipulate specifications. Several large specifications which have been processed by the set-theoretic implementation are presented. A semi-automatic theorem prover for Clear built on top of the Edinburgh LCF system is described. It takes advantage of the structure of Clear specifications to restrict the available information to that which seems relevant to proving the theorem at hand. If the system is unable to prove a theorem automatically the user can attempt the proof interactively using the high-level primitives and inference rules provided. We lay a theoretical foundation for the use of Clear in systematic program development by investigating a new notion of the implementation of a specification by a lower-level specification. This notion extends to handle parameterised specifications. We show that this implementation relation is transitive and commutes with Clear's structuring operations under certain conditions. This means that a large specification can be refined to a program in a gradual and modular fashion, where the correctness of the individual refinements guarantees the correctness of the resulting program.

This thesis focuses on decentralized deadbeat output regulation of discrete-time nonlinear plants that are composed of multiple agents. These agents interact, via scalar-valued signals, in a known structured way represented with a graph. This work is motivated by applications where it is infeasible and/or undesirable to introduce control action within each plant agent; instead, control agents are introduced to interact with certain plant agents, where each control agent focuses on regulating a specific plant agent, called its target. Then, two analyses are carried out to determine if regulation is achieved: targeting analysis is used to determine if control laws can be found to regulate all target agents, then growing analysis is used to determine the effect of those control laws on non-target plant agents. The strength of this novel approach is the intuitively-appealing notion of each control agent focusing on the regulation of just one plant agent. This work goes beyond previous research by generalizing the class of allowable plant dynamics, considering not only arbitrary propagation times through plant agents, but also allowing for non-symmetrical influence between the agents. Moreover, new necessary and sufficient algebraic conditions are derived to determine when targeting succeeds. The main contribution of this work, however, is the development of new easily-verifiable conditions necessary for targeting and/or growing to succeed. These new conditions are valuable due to their simplicity and scalability to large systems. They concern the positioning of control agents and targets as well as the propagation time of signals through the plant, and they help significantly with design decisions. Various graph structures (such as queues, grids, spiders, rings, etc.) are considered and for each, these conditions are used to develop a control scheme with the minimum number of control agents needed.

<p> </p><p>Detta är en studie om elevernas attityder till teoretiska och praktiska läxor. Intresset vaknade</p><p>hos oss efter vår verksamhetsförlagda utbildning (VFU) och den egna skolgången. Alla elever</p><p>har olika sätt att lära sig och vi som pedagoger skall ju sträva efter att individanpassa</p><p>undervisningen. Vi tror att en praktisk läxa skulle kunna stimulera flera elevers sätt att lära</p><p>sig. Det är både en kvalitativ och kvantitativ studie. Vår studie är även experimentell eftersom</p><p>vi har tre grupper som gjort en teoretisk läxa och tre grupper som även gjorde en praktisk läxa</p><p>inför ett läxförhör, båda grupperna är lika viktiga i vår studie. Vi har sedan undersökt vilka</p><p>attityder eleverna har till teoretiska och praktiska läxor genom att lämna ut en enkät för att</p><p>mäta elevernas attityder till teoretisk och praktisk läxa. Studien kommer att genomfördes i</p><p>årskurs åtta. Vi är väl medvetna om att studiens resultat inte går att generalisera. Vi jämförde</p><p>även läxförhöret med ett förhör som gjorts tidigare. Vi avslutade sedan med en intervju med</p><p>läraren till eleverna för att fråga, vad läraren anser om läxförhören och praktiska läxor, samt</p><p>om de praktiska läxorna kan ha påverkat resultaten eller inte. Vi vill med studien testa vårt</p><p>antagande om praktiska läxor kan stimulera elevers olika sätt att lära sig. Studien visar att</p><p>elevernas attityder till läxor är att de föredrar en variation av både teoretiska och praktiska</p><p>läxor.</p><p> </p> / <p>This is a study about attitudes to theoretical and practical homework. Our interest in the</p><p>subject emerged during our practical teacher training but is also influenced from our own</p><p>VFU "practical teacher training" and our own time in school. All students have different ways</p><p>of learning and as pedagogues we ought to try to individualize the education. We believe a</p><p>practical homework could stimulate the students' different ways of learning. This is both a</p><p>qualitative and a quantitative study. Our study is also experimental because we got three</p><p>groups that did theoretical homework and three groups that, in addition, did a practical</p><p>homework before a test. Both groups are important to our study. Then we examined which</p><p>attitudes the students had to theoretical and practical homework by the means of a</p><p>questionnaire, which measured the students attitudes to practical and theoretical homework.</p><p>The study will be made in eight class. We are well aware that you can not generalize. We also</p><p>compared the test with a test the students did previously, before are study took place. We</p><p>completed the study with an interview with the students teacher in order to ask what she</p><p>considered about the test results and practical homework. And if she believes the practical</p><p>homework affects the result of the test. By this study we try the hypothesis that practical</p><p>homework can stimulate students in their different ways of learning. The study shows that the</p><p>students prefer a variation of both theoretical and practical homework.</p>

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-04-29T13:19:13Z No. of bitstreams: 1 arquivo total.pdf: 1827584 bytes, checksum: 8e2c4699b20e87ffce14b44d0467564c (MD5) / Made available in DSpace on 2016-04-29T13:19:13Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 1827584 bytes, checksum: 8e2c4699b20e87ffce14b44d0467564c (MD5) Previous issue date: 2016-02-02 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / To reduce waste and increase the generation of value for customers, more and more construction companies have sought to apply the Lean Construction. However, there is no unanimous formalization of the implementation process and companies lack information about their real capacity to go through a lean transition. As stressed by the literature, one of the key factors for the success of any lean implementation is to assess the readiness of the organization. This paper assumes that this assessment should consider the technical, human and cultural dimensions and their interrelationships. Seeking ways to evaluate, an important tool based on graph theory and matrix algebra, identified in the literature as Graph Theoretic Approach (GTA), has been applied in different contexts, with desirable properties such as the ability to model interactions between criteria and generating hierarchical models for solving complex decision-making problems. Thus, this study aims to develop a readiness assessment method for implementation of Lean Construction using the GTA as a tool for its operationalization. As steps involved in building the method, it was carried out a literature review, in which it was possible to identify the readiness factors and sub-factors considered in the evaluation, and the parameterization of the model, through the establishment of inter-relations between the selected factors and sub-factors. The developed method was tested through the application in construction companies. As a result from the application, it was obtained the classification of two companies which showed insufficient and partial readiness levels. From the case studies, it was concluded that the proposed method is suitable for its purpose, meeting the criteria of feasibility, usability and utility. The method results allow to provide a diagnostic of the current situation of construction companies, which serves as a driver for change initiatives towards the Lean Construction. / Visando reduzir desperdícios e aumentar a geração de valor para seus clientes finais, cada vez mais empresas construtoras tem buscado aplicar a Construção Enxuta. O que se constata é que não há uma formalização unânime do processo de implementação e que as empresas carecem de informações sobre sua real capacidade para passar por um processo de transição enxuta. Como ressalta a literatura, um dos fatores chave para o sucesso de qualquer implementação enxuta consiste em avaliar a prontidão da organização. Esta pesquisa parte do pressuposto que essa avaliação deve considerar as dimensões de ordem técnica, humana e cultural e suas inter-relações. Na busca de meios para a avaliação, uma importante ferramenta baseada na teoria dos grafos e álgebra matricial, identificada na literatura como Graph Theoretic Approach (GTA), vem sendo aplicada em diversos contextos, apresentando propriedades desejáveis como a capacidade de modelar interações de critérios e de gerar modelos hierárquicos para resolução de problemas de tomada de decisões complexas. Desta forma, este trabalho tem como objetivo desenvolver um método de avaliação de prontidão para implementação da Construção Enxuta utilizando a GTA como ferramenta para sua operacionalização. Como etapas inerentes à construção do método foi realizada uma revisão bibliográfica, na qual foi possível identificar os fatores e os subfatores de prontidão considerados na avaliação, e a parametrização do modelo, por meio do estabelecimento das inter-relações entre os fatores e os subfatores selecionados. O método desenvolvido foi testado por meio da aplicação em empresas construtoras. Como resultado da aplicação, obteve-se a classificação de duas empresas avaliadas as quais apresentaram níveis insuficientes e parciais de prontidão. A partir dos estudos de caso, foi possível concluir que o método proposto é adequado aos fins a que se destina, atendendo aos critérios de viabilidade, usabilidade e utilidade. Os seus resultados permitem fornecer um diagnóstico da situação atual das construtoras, o qual serve de balizador para iniciativas de mudança em direção à Construção Enxuta.

Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-10-03T11:36:30Z No. of bitstreams: 1 arquivototal.pdf: 3049650 bytes, checksum: 3c12ba8f608227bcf644c23dbded37d2 (MD5) / Made available in DSpace on 2017-10-03T11:36:30Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3049650 bytes, checksum: 3c12ba8f608227bcf644c23dbded37d2 (MD5) Previous issue date: 2017-02-22 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The formation of business arrangements became a strategy adopted by companies to acquire combined benefits that could not be generated individually. Thus, collaboration emerges as a fundamental characteristic in setting and maintaining interorganizational relationships. Local productive arrangements (APLs), known in the international literature as clusters or industrial districts, are widely discussed in several aspects, for instance, their taxonomy. However, there are research gaps that demand new investigations, such as the collaboration between firms in this type of arrangement. There are papers that discuss the benefits that companies can achieve from collaborative interorganizational relationships, but, in addition, it is necessary to create mechanisms to assess the collaboration level in order to assist managers in decision-making. Therefore, this work aims to develop a model to assess the collaboration in companies participating in APLs, testing it through case studies in five companies of a furniture APL in the state of Paraíba. The proposed model used a support tool named Graph Theoretic Approach (GTA), which was combined with the Delphi technique applied to experts in order to define the interrelationships between attributes. The attributes from literature were classified as assessment factors and sub-factors, by the following hierarchical relationships: governance factor (constituted by sub-factors public policies, institutions support and risks and rewards sharing); geographical proximity factor (constituted by sub-factors tangible resources sharing, information sharing and knowledge sharing); and trust factor (constituted by sub-factors informal links, long-term relationship and reputation). Through qualitative-quantitative analysis, it was identified that, in general, the evaluated companies are in the average level of collaboration, according to the classification scale that was developed. The application of the model contributes to encouraging companies to develop collaborative practices for factors with lower levels. As a result, the proposed model can be considered appropriate for its purposes, allowing a general evaluation of the collaboration in companies that work in APLs. / A formação de arranjos empresarias tornou-se uma estratégia adotada pelas empresas para adquirirem benefícios conjuntos que não poderiam ser gerados individualmente. Neste sentido, a colaboração surge como uma característica fundamental no estabelecimento e na manutenção dos relacionamentos interorganizacionais. Os arranjos produtivos locais (APLs), conhecidos na literatura internacional como clusters ou industrial districts, são amplamente discutidos na academia em relação a diversos aspectos, como, por exemplo, sua taxonomia. No entanto, existem lacunas de pesquisa que apontam para novas investigações, como é o caso da colaboração entre empresas nesse tipo de arranjo. Há pesquisas que discutem sobre os benefícios que as empresas podem obter a partir das relações interorganizacionais colaborativas, mas, além disso, é necessário criar mecanismos de avaliação da colaboração que possam auxiliar os gestores na tomada de decisão. Dessa forma, este trabalho tem como principal objetivo desenvolver um modelo para avaliar a colaboração em empresas participantes de APLs, aplicando-o por meio de estudos de caso em cinco empresas do APL de móveis do Estado da Paraíba. Para o desenvolvimento do modelo, utilizou-se uma ferramenta denominada de graph theoretic approach (GTA), cuja definição das inter-relações entre os atributos de avaliação se deu por meio da aplicação da técnica Delphi, com pesquisadores especialistas sobre a temática. Os atributos levantados na literatura foram denominados de fatores e subfatores de avaliação, com as seguintes relações hierárquicas: fator governança (composto pelos subfatores suporte de políticas públicas, suporte de instituições de apoio e compartilhamento de riscos e recompensas); fator proximidade geográfica (composto pelos subfatores compartilhamento de recursos tangíveis, compartilhamento de informações e compartilhamento de conhecimento); e fator confiança (composto pelos subfatores vínculos informais, relacionamento de longo prazo e reputação). Através da análise quali-quantitativa sobre o tema investigado, verificou-se que, em geral, as empresas avaliadas encontram-se no nível médio de colaboração, de acordo com a escala de classificação adotada. A aplicação do modelo contribui para incentivar as empresas a desenvolverem práticas colaborativas para os fatores com menores índices. Foi possível concluir que o modelo proposto é adequado para os seus devidos fins, estabelecendo uma avaliação geral da colaboração em empresas que atuam em APLs.

Nesta tese é apresentado um novo método de reconstrução de imagens, por tomografia de transmissão, de projeções sujeitas a ruído na contagem de fótons. O método de reconstrução selecionado utiliza a técnica POCS (Projections Onto Convex Sets). A estimação das projeções originais a partir das observações ruidosas se dá por meio de quatro métodos: a) estimação utilizando o critério MAP (Maximum a Posteriori); b) filtragem nos coeficientes wavelets das projeções ruidosas; c) aplicação do filtro de Wiener pontual e d) aplicação do filtro de Goodman-Belsher. É apresentado o resultado da reconstrução após a estimação das projeções, mostrando o ISNR (Improvement Signal-to-Noise Ratio) entre as imagens reconstruídas, a partir das projeções ruidosas, com a técnica POCS, estimando as projeções e sem a realização da estimação. Foram utilizados, para reconstrução tomográfica, projeções de corpos de prova obtidos por meio de simulação e também projeções obtidas experimentalmente no minitomógrafo do CNPDIA - EMBRAPA. O uso de estimação sobre as projeções ruidosas mostrou-se eficaz para melhorar a relação sinal-ruído na imagem final, pois esse pré-processamento faz com que os conjuntos impostos pelas projeções sejam mais restritivos. Deve-se observar que a melhoria das imagens obtidas com o uso de filtragem das projeções é obtida com uma relação custo-benefício bastante baixa, pois a maior parte do custo computacional está na fase de reconstrução das imagens. / In this thesis is pesented a new method for image reconstruction, by transmission tomography, for projections under noise in the counting of photons. The selected method of reconstruction uses the POCS (Projections Onto Convex Sets) technique. The estimation of the original projections from the noisy projections observed is performed through four methods: a) estimation using the MAP (Maximum a Posteriori) criteria; b) through of filtering of the wavelets coefficients of the noisy projections; c) using the pointwise Wiener filter and d) using the Goodman-Belsher filter. We present the result of reconstruction after projection estimation, showing the ISNR (Improvement Signal-to-Noise Ratio) between the reconstructed images on noisy projections, using POCS technique after the estimated projections and without this estimation. We use, for tomographic reconstruction, test body projections obtained through simulation and also projections obtained experimentally in the minitomograph scanner of CNPDIA-EMBRAPA. The use of estimation on noisy projections demonstrated to be efficient in improving the signalnoise ratio in the final image, since this pre-processing makes the sets that projections more restrictive. We should observe that the use of projection filtering is obtained with a cost-benefit ratio rather low, since the largest part of the computational effort is in the image reconstruction phase.