Orientador: José Luiz Boldrini / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-22T23:56:27Z (GMT). No. of bitstreams: 1 SilvaFilho_CiceroAlfredoda_D.pdf: 1540276 bytes, checksum: fa10c28a1782367f39180dfe7a92ec2b (MD5) Previous issue date: 2013 / Resumo: O objetivo do trabalho é o de analisar de forma matematicamente rigorosa dois problemas de controle ótimo com restrições dadas por sistemas de equações diferenciais que incluem a equação de transporte com renovação, bem como um conjunto de restrições para a classe dos controles. Tais sistemas modelam as dinâmicas de populações de mosquitos (considerados em dois grupos: indivíduos jovens, em fase aquática, e adultos) e suas interações com os recursos do meio ambiente (alimentos, por exemplo); além disso, leva-se em conta o processo de maturação da população jovem, a qual fica, portanto estruturada por idade e cuja dinâmica é governada por uma equação de transporte com renovação. Nestes problemas, as populações estão submetidas à atuação de um controle externo, um agente químico, por exemplo, que afeta as respectivas taxas de mortalidade, modificando-as; no caso dos indivíduos jovens, tal atuação pode depender do nível de maturação (idade) do indivíduo. O primeiro problema considera apenas a variação no tempo da população de adultos, enquanto que o segundo problema leva em conta também a sua distribuição espacial. Em cada um desses problemas, mostra-se, sob certas condições, a existência de controle ótimo, isto é, um controle que minimiza um dado funcional objetivo; obtêm-se também as correspondentes condições de otimalidade que caracterizam tal controle ótimo / Abstract: The objective of this work is to analyze in a mathematically rigorous way two optimal control problems with restrictions given by systems of differential equations including the transport equation with renewal, as well as, a restriction set for the controls. Such systems model the dynamics of mosquito populations (considered in two groups: young individual, in aquatic phase, and adults) and their interaction with the environmental resources (food material, for instance); moreover, the maturation process of the population of young individuals is taken in consideration, and thus it becomes age structured and its dynamics is governed by a transport equation with renewal. In these problems, the populations are submitted to the action of an external control, a chemical agent, for instance, which affects the respective mortality rates, changing them; in the case of the young individuals, such action may depend on the individual maturation level. The firs problem considers only the time variation of the adult population; the second problem takes in consideration also its spatial distribution. In each of those problems, it is shown that, under certain conditions, there exists optimal contra, that is, a control minimizing a given objective functional; the associated optimality conditions characterizing such optimal controls are also obtained / Doutorado / Matematica Aplicada / Doutor em Matemática Aplicada

Orientador: Jaime Angulo Pava / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-04T02:39:00Z (GMT). No. of bitstreams: 1 Moura_RogerPeresde_D.pdf: 2234766 bytes, checksum: 9c36c9be07d4a5910fabe79366fd1e13 (MD5) Previous issue date: 2005 / Resumo: Neste trabalho estabelecemos algumas propriedades da equação de Schr6dinger nãolinear não-local (NLSNL), em especial as relacionadas ao problema de Cauchy. Primeiramente fizemos um capítulo preliminar de notações e teoria básica utilizada no esta- belecimento dos resultados; essa parte também visa facilitar a leitura do trabalho. Em seguida apresentamos o principal resultado: boa colocação local para o problema de valor inicial (problema de Cauchy) associado à equação NLSNL para dados iniciais pequenos nos espaços de Sobolev reais usuais de ordem maior que três meios; o método permite estabelecer que a aplicação dado inicial-solução é suave. No capítulo seguinte provamos o mesmo resultado para a equação de Schr6dinger não-linear não-Iocal intermediária (INLSNL), a qual é mais geral que a outra. Depois estabelecemos boa colocação para a equação NLSNL em espaços de Sobolev com peso. Em outro capítulo apresentamos um resultado de má colocação: estabelecemos que não se pode obter boa colocação local, em espaços de Sobolev de índice negativo, para o PVI associado à equação NLSNL por meio de método iterativo de Picard; como conseqüência, a aplicação dado-solução não é suave nesses espaços. Provamos também, fazendo uso de uma identidade de Pohozaev, a não existência de soluções standing waves para a equação NLS não-local. Finalizamos com um capítulo onde exibimos alguns problemas interessantes relacionados principalmente à equação NLSNL e algumas possíveis dificuldades a serem enfrentadas em uma eventual tentativa de solucioná-Ios / Abstract: ln this work we establish some properties of the nonlocal nonlinear Schrodinger equation (NLSNL). First of alI, we present a preliminary chapter with notations and basic theory used to establish our results; that part also seeks to facilitate the reading of this work. Soon afterwards comes the main result: local welI-posedness for the initial value problem (the Cauchy problem or lVP) for the NLSNL equation with initial data in real Sobolev spaces of index larger than three and a half; the method of proof alIows to es- tablish that the data-solution map is smooth. ln the folIowing chapter we proved that previous result for the intermediate nonlocal nonlinear Schrüdinger (lNLSNL), which is more general than the NLSNL equation. After that we establish local welI-posedness for the NLSNL equation in weighted Sobolev spaces. ln another chapter the ill-posedness issue is discussed: we established that one cannot obtain local welI-posedness, in Sobolev spaces of negative index, for the lVP associated to NLSNL equation through a iterative Picard method; as a consequence, the data-solution map is not smooth in those spaces. We also proved, making use of a Pohozaev's identity, the no-existence of standing waves solutions for the NLSNL equation. We concluded with a chapter where we exhibited some interesting problems mainly related to the NLSNL equation and possible difficulties to be faced in an eventual attempt of solving them / Doutorado / Matematica / Doutor em Matemática

Orientadores: Marko Antonio Rojas Medar, Francisco Guillen Gonzalez / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-04T03:26:41Z (GMT). No. of bitstreams: 1 Lopes_FranciscoPauloMarques_D.pdf: 884224 bytes, checksum: 86ca0f1458af3355beee2bde5fccec8e (MD5) Previous issue date: 2005 / Resumo: Neste trabalho abordaremos basicamente três problemas de controle sujeitos a equações diferencias parciais. O primeiro problema a ser tratado é um sistema distribuído governado por um modelo de solidificação de um líquido puro, o segundo é um sistema distribuído governado pelas equações de Navier - Stokes e o terceiro é um problema de controle com vários objetivos locais mais um objetivo diferente associado a um controle global. Nos dois primeiros problemas, apresentaremos as condições necessárias de otimalidade local via, o assim chamado, formalismo de Dubovitskii e Milyutin; além disso, apresentaremos alguns resultados sobre os equilíbrios de Nash e de Pareto para os problemas de otimização vetorial associados aos problemas com multiobjetivos. Para finalizar, usaremos alguns resultados da teoria de equações parabólicas e da análise funcional para mostrar a existência de um equilíbrio do tipo Stackelberg - Nash para o terceiro problema / Abstract: In this work we will investigate basically three control problems subject to partial diferential equations. The first problem to be treated is distributed system governed by a model for solidification of a pure liquid; the second is a distributed system governed Navier - Stokes equations and the third, one is control problem with several local objectives plus a diferent objective associated to a global control. In the first two problems, we will present necessary conditions of local optimality via, the so called, formalism of Dubovitskii and Milyutin; besides, we will introduce some results on the equilirio of Nash and Pareto for the vector problems optimization associated with the problems case multiobjetive. To conclude we will use some results of the theory of parabolic equations and the functional analysis to show the existence of an equilibrio of the type Stackelberg - Nash for the third problem / Doutorado / Matematica / Doutor em Matemática

Orientador: Djairo Guedes de Figueiredo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Científica / Made available in DSpace on 2018-08-04T17:25:30Z (GMT). No. of bitstreams: 1 Pereira_FabioRodrigues_D.pdf: 1468332 bytes, checksum: 3e4d6ad380a672eddddbebbfbe9c85f4 (MD5) Previous issue date: 2005 / Doutorado / Doutor em Matemática

This work addresses various applications pertaining to the design, modelling and animation of parametric surfaces using elliptic Partial Differential Equations (PDE) which are produced via the PDE method. Compared with traditional surface generation techniques, the PDE method is an effective technique that can represent complex three-dimensional (3D) geometries in terms of a relatively small set of parameters. A PDE-based surface can be produced from a set of pre-configured curves that are used as the boundary conditions to solve a number of PDE. An important advantage of using this method is that most of the information required to define a surface is contained at its boundary. Thus, complex surfaces can be computed using only a small set of design parameters. In order to exploit the advantages of this methodology various applications were developed that vary from the interactive design of aircraft configurations to the animation of facial expressions in a computer-human interaction system that utilizes an artificial intelligence (AI) bot for real time conversation. Additional applications of generating cyclic motions for PDE based human character integrated in a Computer-Aided Design (CAD) package as well as developing techniques to describe a given mesh geometry by a set of boundary conditions, required to evaluate the PDE method, are presented. Each methodology presents a novel approach for interacting with parametric surfaces obtained by the PDE method. This is due to the several advantages this surface generation technique has to offer. Additionally, each application developed in this thesis focuses on a specific target that delivers efficiently various operations in the design, modelling and animation of such surfaces.

The investigations presented in the thesis are theoretical studies of magnetohydrodynamic flows, heat and mass transfer in Newtonian/non-Newtonian cooling liquids, due to horizontal/vertical stretching sheet. The theoretical studies include the effect of magnetic field, uniform and non-uniform heat source/sink (flow and temperature dependent heat source/sink) effects. The considered problems include flow of viscous fluids in the presence of applied magnetic field and electric field with first order chemical reactions. The viscous incompressible Newtonian fluid flow in porous medium with Darcy-Forchheimmer model, electrically conducting fluid and nanofluid is studied. We introduce innovative techniques for finding solutions of highly nonlinear coupled boundary value problems such as Runge-Kutta method, Perturbation method and Differential Transform Method (DTM).   Chapter 1-2 gives a brief introduction. Chapter 3 focuses on Lie group analysis of MHD flow and heat transfer over a stretching sheet. The effects of viscous dissipation, uniform heat source/sink and MHD on heat transfer are addressed. In Chapter 4-6 we examined the laminar flow, thermocapillary flow of a nanoliquid thin film over an unsteady stretching sheet in presence of MHD and thermal Radiation in different situations. An effective medium theory (EMT) based model is used for the thermal conductivity of the nanoliquid.  Metal and metal oxide nanoparticles are considered in carboxymethyl cellulose (CMC) - water base liquid. In Chapter 7-9 we analyzed, heat and mass transfer in MHD, mixed convection, viscoelastic fluid flow, non-Darcian flow due to stretching sheet in presence of viscous dissipation, non-uniform heat source/sink and porous media have been investigated in different situations.  MHD and viscous dissipation have a significant influence on controlling of the dynamics.    In Chapter 10 the linear stability of Maxwell fluid-nanofluid flow in a saturated porous layer is examined theoretically when the walls of the porous layers are subjected to time-periodic temperature modulations. A modified Darcy-Maxwell model is used to describe the fluid motion, and the nanofluid model used includes the effects of the Brownian motion. The thermal conductivity and viscosity are considered to be dependent on the nanoparticle volume fraction. In Chapter 11 we studied MHD flow in a vertical double passage channel taking into account the presence of the first order chemical reactions. The governing equations are solved by using a regular perturbation technique valid for small values of the Brinkman number and a DTM valid for all values of the Brinkman number.

In this work we present some new results concerning stochastic partial differential and integro-differential equations (SPDEs and SPIDEs) that appear in non-linear filtering. We prove existence and uniqueness of solutions of SPIDEs, we give a comparison principle and we suggest an approximation scheme for the non-local integral operators. Regarding SPDEs, we use techniques motivated by the work of De Giorgi, Nash, and Moser, in order to derive global and local supremum estimates, and a weak Harnack inequality.

We study the Cauchy problem of the derivative nonlinear Schrodinger equation in one space dimension. Using the method of inverse scattering, we prove global well-posedness of the derivative nonlinear Schrodinger equation for initial conditions in a dense and open subset of weighted Sobolev space that can support bright solitons.

Abstract available on page 4 of the document / Thesis (PhD (Mathematics))--University of Pretoria, 2007. / Mathematics and Applied Mathematics / unrestricted

This thesis consists of two parts. We start with some background theory that will be used throughout the thesis. Then, in the first part, we investigate the existence and uniqueness of the solution of the stochastic partial differential equation with two reflecting walls. Then we establish the existence and uniqueness of invariant measure of this equation under some reasonable conditions. In the second part, we study the splitting-up method for approximating the solu- tions of stochastic Stokes equations using resolvent method.