Submitted by Maike Costa (maiksebas@gmail.com) on 2016-03-22T13:00:30Z No. of bitstreams: 1 arquivototal.pdf: 1160851 bytes, checksum: 7135123aaf3823254b3e52ab8d141d6d (MD5) / Made available in DSpace on 2016-03-22T13:00:30Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1160851 bytes, checksum: 7135123aaf3823254b3e52ab8d141d6d (MD5) Previous issue date: 2015-03-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work, we present an introduction to the theory of C0-semigroup (and C0-group) of bounded linear operators, and we show that wave operator in RN is the in nitesimal generator of a C0-group of bounded linear operators in a appropriate Banach space. / Neste trabalho apresentamos uma introdu c~ao a teoria de C0􀀀semigrupos (e C0􀀀gru po) de operadores lineares e limitados, e mostramos que operador de ondas em RN e o gerador in nitesimal de um C0􀀀grupo de operadores lineares e limitados em um espa co de Banach apropriado.

Made available in DSpace on 2016-04-27T16:58:03Z (GMT). No. of bitstreams: 1 dissertacao_ciro_braga.pdf: 851588 bytes, checksum: 2bba61c53f85aca69b0e5e69a8538073 (MD5) Previous issue date: 2003-11-27 / The purpose of our study, the disciplinary initial process of the function in the mathematics discipline is linked to the creation, in 1929, of a new school discipline denominated mathematics, resulting from the union of other three: arithmetic, algebra and geometry. This merger was done from an international reference, whose epicenter was in the ideas of the well-known German mathematician Felix Klein, who proposed together with an introduction of Infinitesimal Calculation, a renewal in high school teaching. Such structural transformation in our schooling mathematics was attested, in 1931, for an educational reform Francisco Campos Reform. The main counsellor and articulator of the mathematics teaching transformation in Brazil was Euclides Roxo, who in addition to being a teacher and the principal of Colégio Pedro II in Rio de Janeiro, became the author of several school text-books that had an outstanding role to the function. To his first innovative volumes, Roxo has also taken the conceptions from a North American professor, Ernst Breslich, which are the subject matters in chapter III. In the following chapter, it is done an analysis of the most representative Brazilian school books during the period in which Francisco Campos Reform was in effect. Grounded mainly on the conceptions of the French researcher Chervel about the functioning of the school disciplines and supported on surveys about acceptance of modernizing movement principles in other countries, such as France and Germany, we conclude that it is possible to have a new look through the results of Euclides Roxo s work in introducing function into the contents of our secundary schooling mathematics / O estudo analisa o processo inicial de disciplinarização do conceito de função. Tal análise está diretamente vinculada à criação, em 1929, de uma nova disciplina escolar denominada matemática, resultante da unificação de três outras: a aritmética, a álgebra e a geometria. Essa fusão foi feita a partir de uma referência internacional, cujo epicentro encontrava-se nas idéias do renomado matemático alemão Felix Klein, que propunha, ao lado da introdução do Cálculo Infinitesimal, uma renovação no ensino secundário. Tal transformação estrutural da matemática escolar brasileira foi referendada, em 1931, por uma reforma educacional - a Reforma Francisco Campos

In this thesis we analyze lumpability of infinite dimensional dynamical systems. Lumping is a method to project a dynamics by a linear reduction operator onto a smaller state space on which a self-contained dynamical description exists. We consider a well-posed dynamical system defined on a Banach space X and generated by an operator F, together with a linear and bounded map M : X → Y, where Y is another Banach space. The operator M is surjective but not an isomorphism and it represents a reduction of the state space. We investigate whether the variable y = M x also satisfies a well-posed and self-contained dynamics on Y . We work in the context of strongly continuous semigroup theory. We first discuss lumpability of linear systems in Banach spaces. We give conditions for a reduced operator to exist on Y and to describe the evolution of the new variable y . We also study lumpability of nonlinear evolution equations, focusing on dissipative operators, for which some interesting results exist, concerning the existence and uniqueness of solutions, both in the classical sense of smooth solutions and in the weaker sense of strong solutions. We also investigate the regularity properties inherited by the reduced operator from the original operator F . Finally, we describe a particular kind of lumping in the context of C*-algebras. This lumping represents a different interpretation of a restriction operator. We apply this lumping to Feller semigroups, which are important because they can be associated in a unique way to Markov processes. We show that the fundamental properties of Feller semigroups are preserved by this lumping. Using these ideas, we give a short proof of the classical Tietze extension theorem based on C*-algebras and Gelfand theory.

The modelling power of Itˆo integrals has a far reaching impact on a spectrum of diverse fields. For example, in mathematics of finance, its use has given insights into the relationship between call options and their non-deterministic underlying stock prices; in the study of blood clotting dynamics, its utility has helped provide an understanding of the behaviour of platelets in the blood stream; and in the investigation of experimental psychology, it has been used to build random fluctuations into deterministic models which model the dynamics of repetitive movements in humans. Finding the quadrature for these integrals using continuous groups or Lie groups has to take families of time indexed random variables, known as Wiener processes, into consideration. Adaptations of Sophus Lie’s work to stochastic ordinary differential equations (SODEs) have been done by Gaeta and Quintero [1], Wafo Soh and Mahomed [2], ¨Unal [3], Meleshko et al. [4], Fredericks and Mahomed [5], and Fredericks and Mahomed [6]. The seminal work [1] was extended in Gaeta [7]; the differential methodology of [2] and [3] were reconciled in [5]; and the integral methodology of [4] was corrected and reconciled in [5] via [6]. Symmetries of SODEs are analysed. This work focuses on maintaining the properties of the Weiner processes after the application of infinitesimal transformations. The determining equations for first-order SODEs are derived in an Itˆo calculus context. These determining equations are non-stochastic. Many methods of deriving Lie point-symmetries for Itˆo SODEs have surfaced. In the Itˆo calculus context both the formal and intuitive understanding of how to construct these symmetries has led to seemingly disparate results. The impact of Lie point-symmetries on the stock market, population growth and weather SODE models, for example, will not be understood until these different results are reconciled as has been attempted here. Extending the symmetry generator to include the infinitesimal transformation of the Wiener process for Itˆo stochastic differential equations (SDEs), has successfully been done in this thesis. The impact of this work leads to an intuitive understanding of the random time change formulae in the context of Lie point symmetries without having to consult much of the intense Itˆo calculus theory needed to derive it formerly (see Øksendal [8, 9]). Symmetries of nth-order SODEs are studied. The determining equations of these SODEs are derived in an Itˆo calculus context. These determining equations are not stochastic in nature. SODEs of this nature are normally used to model nature (e.g. earthquakes) or for testing the safety and reliability of models in construction engineering when looking at the impact of random perturbations. The symmetries of high-order multi-dimensional SODEs are found using form invariance arguments on both the instantaneous drift and diffusion properties of the SODEs. We then apply this to a generalised approximation analysis algorithm. The determining equations of SODEs are derived in an It¨o calculus context. A methodology for constructing conserved quantities with Lie symmetry infinitesimals in an Itˆo integral context is pursued as well. The basis of this construction relies on Lie bracket relations on both the instantaneous drift and diffusion operators.

Made available in DSpace on 2016-04-27T16:58:09Z (GMT). No. of bitstreams: 1 dissertacao_marly_nardi_ferraz_nunes.pdf: 523449 bytes, checksum: 60d6904ff936356079c395ae72c8d18a (MD5) Previous issue date: 2001-05-11 / This study discribes research performed with the help of activities that place great emphasis upon the student s actions. Teaching and learning the concepts connected with limits and infinite has proved a hard task, often with unsatisfactory results. In France, Aline Robert has done research with over 1.300 students on the acquisition of the concept of convergence of numerical sequences. The same researcher has concluded that the learning process would be more effective if this concept was taught by means of activities conducted by the students themselves. Inspired by her investigations and also based on Piaget s constructivist theory, we carried out activity work with students from a Faculty of Mathematics, who had still not been introduced to the studies of limits and infinitesimal calculus. The aim of our work was to enable the students to better assimilate concepts related to the convergence of sequences. Based on principles of Didactical Engineering, we prepared and applied a sequence composed of ten activities and one post-test. During these activities we utilized problems to work on the concepts related to numerical sequences and convergence. From analysis of the results we concluded that the procedure described here promoted, in general, an increase in knowledge of the students and, in particular, the acquisition, by most students, of notions related to the concept of convergence of numerical sequences. This experience represented a rupture of our traditional pedagogical practices in favor of a new dynamics, which required of ourselves and of the students a change in posture. Among the conclusions are issues that can be the object of further studies / Este trabalho relata uma pesquisa realizada por meio de atividades que privilegiam a ação dos estudantes. O ensino e a aprendizagem dos conceitos relacionados com limites e infinito têm se mostrado árduos e, muitas vezes, com resultados insatisfatórios. Aline Robert realizou, na França, uma pesquisa com mais de 1.300 estudantes sobre a aquisição do conceito de convergência de seqüências numéricas. A pesquisadora concluiu que a aprendizagem seria mais efetiva se o ensino desse conceito fosse conduzido através de atividades realizadas pelos alunos. Inspirados nessa pesquisa, e baseados na teoria construtivista de Piaget, desenvolvemos um trabalho de atividades com alunos de um curso de licenciatura em matemática, que não haviam ainda sido introduzidos no estudo dos limites e do cálculo infinitesimal. O objetivo desse trabalho é propiciar aos alunos a apropriação de conceitos relacionados com a convergência de seqüências. Utilizando-nos dos princípios da Engenharia Didática, elaboramos e aplicamos uma seqüência composta de 10 atividades e um pós-teste. Nessas atividades foram trabalhados, através de problemas, os conceitos relacionados com seqüências numéricas e convergência. A análise dos resultados nos permitiu concluir que o procedimento empregado possibilitou, em geral, o progresso do conhecimento dos alunos, e em particular a aquisição, pela maioria dos estudantes, de noções articuladas ao conceito de convergência de seqüências numéricas. Essa experiência representou uma ruptura de nossa prática pedagógica tradicional, em favor de uma nova dinâmica, que exigiu de nós e dos alunos uma mudança de postura. Dentre as conclusões, foram levantadas questões que poderão ser objeto de futuras pesquisas

Ο σκοπός της εργασίας είναι η παρουσίαση της έννοιας της συμμετρίας ως έναν μετασχηματισμό που απεικονίζει τη λύση μιας Δ.Ε. σε μια άλλη Δ.Ε. διατηρώντας αναλλοίωτη και αμετάβλητη τη μορφή της. Παρουσιάζεται επίσης η μέθοδος της αναλλοίωτης διαφόρισης και ο αλγόριθμος Lie. / -

No presente trabalho é descrita uma formulação para modelos constitutivos elastoviscoplásticos, considerando deformações infinitesimais e finitas. Os modelos são formulados em um contexto da termodinâmica de variáveis internas usando fundamentos de análise convexa. As equações de evolução são obtidas a partir do princípio da máxima dissipação, o qual desempenha um importante papel na abordagem adotada, a qual consiste na generalização do modelo reológico de Bingham. O problema constitutivo de valor inicial local é solucionado por um esquema de integração implícita combinado a um algoritmo de mapeamento de retorno. O problema de valor no contorno e inicial global, considerando casos quasi-estáticos, é solucionado por meio do método dos elementos finitos (MEF) empregando também um método de integração implícita. Esta estratégia é implementada empregando os modelos constitutivos viscoplásticos linear e não linear de Perzyna e o modelo de Perié. A implementação computacional é avaliada por meio da comparação dos resultados numéricos a soluções analíticas e também a problemas padrões disponíveis na literatura. Os resultados obtidos são importantes para avaliar o comportamento e as características dos modelos viscoplásticos na análise dos fenômenos de dependência da taxa de deformação e de relaxação de tensão. Embora os três modelos se mostrem adequados à captura destes fenômenos, uma atenção especial deve ser dada ao modelo não linear de Perzyna, pois este não recupera o modelo invíscido como um caso limite, além disso, apresenta mal condicionamento no algoritmo de mapeamento de retorno. / In this work an elastic-viscoplastic constitutive formulation is described, considering infinitesimal and finite deformations. The models are formulated inside a thermodynamic with internal variables framework using fundamentais from convex analysis. The evolution equations are obtained from the maximum dissipation principie, which plays an important role on the approach adopted, which is the generalization of the Bingham rheological model. The local initial value problem is solved by an implicit integration scheme with a return mapping algorithm. The global initial boundary value problem is solved by the finite element method (FEM) also employing an implicit integration method. The strategy is implemented employing the linear and nonlinear Perzyna and the Perié viscoplastic models. The computational implementation is evaluated by comparing the numerical results with analytical solutions and with benchmarks available in the literature. The results obtained are important to evaluate the behavior and the characteristics of the models on the analysis of rate-dependency and stress relaxation. The three models were suitable to predict these phenomena. However, a special attention is needed on the nonlinear Perzyna model, because it does not recover the inviscid model as a limit case. Further, it presents ill-conditioning in the return mapping algorithm.

No presente trabalho é descrita uma formulação para modelos constitutivos elastoviscoplásticos, considerando deformações infinitesimais e finitas. Os modelos são formulados em um contexto da termodinâmica de variáveis internas usando fundamentos de análise convexa. As equações de evolução são obtidas a partir do princípio da máxima dissipação, o qual desempenha um importante papel na abordagem adotada, a qual consiste na generalização do modelo reológico de Bingham. O problema constitutivo de valor inicial local é solucionado por um esquema de integração implícita combinado a um algoritmo de mapeamento de retorno. O problema de valor no contorno e inicial global, considerando casos quasi-estáticos, é solucionado por meio do método dos elementos finitos (MEF) empregando também um método de integração implícita. Esta estratégia é implementada empregando os modelos constitutivos viscoplásticos linear e não linear de Perzyna e o modelo de Perié. A implementação computacional é avaliada por meio da comparação dos resultados numéricos a soluções analíticas e também a problemas padrões disponíveis na literatura. Os resultados obtidos são importantes para avaliar o comportamento e as características dos modelos viscoplásticos na análise dos fenômenos de dependência da taxa de deformação e de relaxação de tensão. Embora os três modelos se mostrem adequados à captura destes fenômenos, uma atenção especial deve ser dada ao modelo não linear de Perzyna, pois este não recupera o modelo invíscido como um caso limite, além disso, apresenta mal condicionamento no algoritmo de mapeamento de retorno. / In this work an elastic-viscoplastic constitutive formulation is described, considering infinitesimal and finite deformations. The models are formulated inside a thermodynamic with internal variables framework using fundamentais from convex analysis. The evolution equations are obtained from the maximum dissipation principie, which plays an important role on the approach adopted, which is the generalization of the Bingham rheological model. The local initial value problem is solved by an implicit integration scheme with a return mapping algorithm. The global initial boundary value problem is solved by the finite element method (FEM) also employing an implicit integration method. The strategy is implemented employing the linear and nonlinear Perzyna and the Perié viscoplastic models. The computational implementation is evaluated by comparing the numerical results with analytical solutions and with benchmarks available in the literature. The results obtained are important to evaluate the behavior and the characteristics of the models on the analysis of rate-dependency and stress relaxation. The three models were suitable to predict these phenomena. However, a special attention is needed on the nonlinear Perzyna model, because it does not recover the inviscid model as a limit case. Further, it presents ill-conditioning in the return mapping algorithm.

No presente trabalho é descrita uma formulação para modelos constitutivos elastoviscoplásticos, considerando deformações infinitesimais e finitas. Os modelos são formulados em um contexto da termodinâmica de variáveis internas usando fundamentos de análise convexa. As equações de evolução são obtidas a partir do princípio da máxima dissipação, o qual desempenha um importante papel na abordagem adotada, a qual consiste na generalização do modelo reológico de Bingham. O problema constitutivo de valor inicial local é solucionado por um esquema de integração implícita combinado a um algoritmo de mapeamento de retorno. O problema de valor no contorno e inicial global, considerando casos quasi-estáticos, é solucionado por meio do método dos elementos finitos (MEF) empregando também um método de integração implícita. Esta estratégia é implementada empregando os modelos constitutivos viscoplásticos linear e não linear de Perzyna e o modelo de Perié. A implementação computacional é avaliada por meio da comparação dos resultados numéricos a soluções analíticas e também a problemas padrões disponíveis na literatura. Os resultados obtidos são importantes para avaliar o comportamento e as características dos modelos viscoplásticos na análise dos fenômenos de dependência da taxa de deformação e de relaxação de tensão. Embora os três modelos se mostrem adequados à captura destes fenômenos, uma atenção especial deve ser dada ao modelo não linear de Perzyna, pois este não recupera o modelo invíscido como um caso limite, além disso, apresenta mal condicionamento no algoritmo de mapeamento de retorno. / In this work an elastic-viscoplastic constitutive formulation is described, considering infinitesimal and finite deformations. The models are formulated inside a thermodynamic with internal variables framework using fundamentais from convex analysis. The evolution equations are obtained from the maximum dissipation principie, which plays an important role on the approach adopted, which is the generalization of the Bingham rheological model. The local initial value problem is solved by an implicit integration scheme with a return mapping algorithm. The global initial boundary value problem is solved by the finite element method (FEM) also employing an implicit integration method. The strategy is implemented employing the linear and nonlinear Perzyna and the Perié viscoplastic models. The computational implementation is evaluated by comparing the numerical results with analytical solutions and with benchmarks available in the literature. The results obtained are important to evaluate the behavior and the characteristics of the models on the analysis of rate-dependency and stress relaxation. The three models were suitable to predict these phenomena. However, a special attention is needed on the nonlinear Perzyna model, because it does not recover the inviscid model as a limit case. Further, it presents ill-conditioning in the return mapping algorithm.

The program MANDO efficiently performs computations involving pairs of operators, a single operator, and operators applied to functions, saving time and cost over pencil-·and-paper methods. A versatile but compact data structure, defined under SPIT-BOL's facility for creation of datatypes, contains the operators (and functions) and provides a means for systematically referencing their relevant parts. On input, functions and operators are written in a restricted but natural string format, for which the program can readily convert them to the internal data structure. Central to the method of operation of the derivative routine is its ability to differentiate a function written as a string. This allows for a certain compactness in the internal form. To counteract the relative slowness of string processing in the derivative routine, the program keeps a table of derivatives repeated during the processing . The table is checked for the presence of the function and its derivative before the derivative sequence is applied. Some simplification is performed. The simplification relies on the ordering sequence, followed by a sequence which cancels or combines terms that are alike, except, in general, for numerical multipliers.