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Growth conditions and uniqueness of the Cauchy problem for the evolutionary infinity Laplacian

Leonori, Tommaso; Urbano, José Miguel
Fonte: Centro de Matemática da Universidade de Coimbra Publicador: Centro de Matemática da Universidade de Coimbra
Tipo: Pré-impressão
ENG
Relevância na Pesquisa
36.64%
We study the Cauchy problem for the parabolic infinity Laplace equation. We prove a new comparison principle and obtain uniqueness of viscosity solutions in the class of functions with a polinomial growth at infinity, improving previous results obtained assuming a linear growth.

Sistemas de monitorização infinity - Optimização do workflow clínico

Novais, Nuno Miguel Osório
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
36.79%
O fluxo de trabalho clínico está directamente relacionado com o impacto da inserção dos equipamentos médicos, nomeadamente das suas funcionalidades, fiabilidade e custos de manutenção. O transporte intra-hospitalar de pacientes em condição crítica é um processo que envolve um conjunto de riscos para a saúde dos pacientes. A Infinity Docking Station (IDS), um sistema de conexão com monitores de sinais vitais tem como principal aplicação a optimização deste processo. Com a realização deste projecto, pretende-se avaliar o impacto da inserção da IDS em ambiente hospitar, nomeadamente nos processos de transporte e outras tarefas relacionadas com sistemas de monitorização. De igual modo, pretende-se avaliar a fiabilidade e custo de manutenção dos sistemas de monitorização da Draeger Medical, nomeadamente de Monitores de Sinais Vitais e Centrais de Monitorização. A IDS mostra ser um equipamento com um grande impacto nos processos hospitalares. Com a utilização desta o processo é mais simples, o clínico pode focalizar a atenção no paciente, necessita de um menor número de recursos tecnológicos, permite uma redução no tempo de transporte em cerca de 70% (Fonte Draeger Medical) e serve inclusive de interface entre os monitores de sinais vitais e outros sistemas. Resultados preliminares sugerem que os sistemas de monitorização da Draeger Medical são extremamente fiáveis e que os custos de manutenção...

H(infinity) filtering for rectangular discrete-time descriptor systems

ISHIHARA, Joao Y.; TERRA, Marco H.; ESPINOZA, B. M.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.56%
This paper deals with the H(infinity) recursive estimation problem for general rectangular time-variant descriptor systems in discrete time. Riccati-equation based recursions for filtered and predicted estimates are developed based on a data fitting approach and game theory. In this approach, the nature determines a state sequence seeking to maximize the estimation cost, whereas the estimator tries to find an estimate that brings the estimation cost to a minimum. A solution exists for a specified gamma-level if the resulting cost is positive. In order to present some computational alternatives to the H(infinity) filters developed, they are rewritten in information form along with the respective array algorithms. (C) 2009 Elsevier Ltd. All rights reserved.; Fundacao de Amparoa Pesquisa do Estado de sao Paulo (FAPESP)[04/03826-8]; Fundacao de Amparoa Pesquisa do Estado de sao Paulo (FAPESP)[03/12574-0]; Cnpq[310852/2006-4]

Experimental results on the nonlinear H(infinity) control via quasi-LPV representation and game theory for wheeled mobile robots

INOUE, Roberto S.; SIQUEIRA, Adrian A. G.; TERRA, Marco H.
Fonte: CAMBRIDGE UNIV PRESS Publicador: CAMBRIDGE UNIV PRESS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.56%
In this paper, nonlinear dynamic equations of a wheeled mobile robot are described in the state-space form where the parameters are part of the state (angular velocities of the wheels). This representation, known as quasi-linear parameter varying, is useful for control designs based on nonlinear H(infinity) approaches. Two nonlinear H(infinity) controllers that guarantee induced L(2)-norm, between input (disturbances) and output signals, bounded by an attenuation level gamma, are used to control a wheeled mobile robot. These controllers are solved via linear matrix inequalities and algebraic Riccati equation. Experimental results are presented, with a comparative study among these robust control strategies and the standard computed torque, plus proportional-derivative, controller.

Galerkin Method and Weighting Functions Applied to Nonlinear H(infinity) Control with Output Feedback

FERREIRA, Henrique Cezar; SALES, Roberto Moura; ROCHA, Paulo Henrique Da
Fonte: SAGE PUBLICATIONS LTD Publicador: SAGE PUBLICATIONS LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.56%
This paper considers two aspects of the nonlinear H(infinity) control problem: the use of weighting functions for performance and robustness improvement, as in the linear case, and the development of a successive Galerkin approximation method for the solution of the Hamilton-Jacobi-Isaacs equation that arises in the output-feedback case. Design of nonlinear H(infinity) controllers obtained by the well-established Taylor approximation and by the proposed Galerkin approximation method applied to a magnetic levitation system are presented for comparison purposes.

On the convergence of successive Galerkin approximation for nonlinear output feedback H(infinity) control

FERREIRA, Henrique C.; ROCHA, Paulo H.; SALES, Roberto M.
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.56%
Although the formulation of the nonlinear theory of H(infinity) control has been well developed, solving the Hamilton-Jacobi-Isaacs equation remains a challenge and is the major bottleneck for practical application of the theory. Several numerical methods have been proposed for its solution. In this paper, results on convergence and stability for a successive Galerkin approximation approach for nonlinear H(infinity) control via output feedback are presented. An example is presented illustrating the application of the algorithm.

Fixed-point DSP implementation of nonlinear H(infinity) controller for large gap electromagnetic suspension system

ROCHA, Paulo H. da; FERREIRA, Henrique C.; PORSCH, Michael C.; SALES, Roberto M.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.56%
Electromagnetic suspension systems are inherently nonlinear and often face hardware limitation when digitally controlled. The main contributions of this paper are: the design of a nonlinear H(infinity) controller. including dynamic weighting functions, applied to a large gap electromagnetic suspension system and the presentation of a procedure to implement this controller on a fixed-point DSP, through a methodology able to translate a floating-point algorithm into a fixed-point algorithm by using l(infinity) norm minimization due to conversion error. Experimental results are also presented, in which the performance of the nonlinear controller is evaluated specifically in the initial suspension phase. (C) 2009 Elsevier Ltd. All rights reserved.

Application of H-infinity Theory to a 6 DOF Flight Simulator Motion Base

Becerra-Vargas, Mauricio; Belo, Eduardo Morgado
Fonte: ABCM BRAZILIAN SOC MECHANICAL SCIENCES & ENGINEERING; RIO DE JANEIRO RJ Publicador: ABCM BRAZILIAN SOC MECHANICAL SCIENCES & ENGINEERING; RIO DE JANEIRO RJ
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.45%
The purpose of this study is to apply inverse dynamics control for a six degree of freedom flight simulator motion system. Imperfect compensation of the inverse dynamic control is intentionally introduced in order to simplify the implementation of this approach. The control strategy is applied in the outer loop of the inverse dynamic control to counteract the effects of imperfect compensation. The control strategy is designed using H-infinity theory. Forward and inverse kinematics and full dynamic model of a six degrees of freedom motion base driven by electromechanical actuators are briefly presented. Describing function, acceleration step response and some maneuvers computed from the washout filter were used to evaluate the performance of the controllers.; FAPESP (Sao Paulo State Foundation for Research Support - Brazil) [2005/25486-6]; FAPESP (Sao Paulo State Foundation for Research Support Brazil)

Regularity at infinity and global fibrations of real algebraic maps; Regularidade no infinito e fibrações globais de aplicações algébricas reais

Dias, Luis Renato Gonçalves
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/02/2013 EN
Relevância na Pesquisa
36.69%
Let f : 'K POT. ' be a 'C POT. 2' semi-algebraic mapping for K = R and a polynomial mapping for K = C. It is well-known that f is a locally trivial topological fibration over the complement of the bifurcation set B(f), also called atypical set. In this work, we consider the notion of t-regularity and 'ho E'-regularity to study the bifurcation set of semi-algebraic mappings f : 'R POT. n' 'ARROW' 'R POT. p' and polynomial mappings f : 'C POT. n' 'ARROW' 'C POT. p'. We show that t-regularity is equivalent to regularity conditions at infinity which have been used by Rabier (1997), Gaffney (1999), Kurdyka, Orro and Simon (2000) and Jelonek (2003) in order to control the asymptotic behaviour of mappings. In addition, we prove that t-regularity implies 'ho E'-regularity. The 'ho E'-regularity enables one to define the set of asymptotic non 'ho E'-regular values S(f) 'This contained' ' K POT. p', and the set 'A IND. 'ho E'' := f(Singf) U S(f). For 'C POT. 2' semi-algebraic mappings f : 'R POT. n' ARROW ' 'R POT. p' and polynomial mappings f : 'C POT. n' 'ARROW' 'C POT. p', based on a partial Thom stratification at infinity, we rove that S(f) and 'A IND. ho E' are closed real semi-algebraic sets of dimension at most p - 1 (real dimension at most 2p - 2...

O infinito na matemática; Infinity in mathematics

Borges, Bruno Andrade
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/12/2014 PT
Relevância na Pesquisa
36.77%
Nesta dissertação, abordaremos os dois tipos de infinitos existentes: o infinito potencial e o infinito actual. Apresentaremos algumas situações, exemplos que caracterizam cada um desses dois tipos. Focaremo-nos no infinito actual, com o qual discutiremos alguns dos desafios encontrados na teoria criada por Cantor sobre este assunto. Mostraremos também sua importância e a diferença entre este e o infinito potencial. Com isso, buscamos fazer com que o professor compreenda adequadamente os fundamentos matemáticos necessários para que trabalhe, ensine e motive apropriadamente seus alunos no momento em que o infinito e conjuntos infinitos são discutidos em aula. Desta forma, buscamos esclarecer os termos usados e equívocos comuns cometidos por alunos e também professores, muitas vezes enganados ou confundidos pelo senso comum.; In this dissertation, we will discuss the two types of infinities: the potential infinity and the actual infinity. We will present some situations, examples that characterize each of these two types. We will focus on the actual infinity, with which we will discuss some of the challenges found in the theory created by Cantor on this subject. We will also show its importance and the difference between this and the potential infinity. Thus...

H-infinity Control Design for Time-Delay Linear Systems: A Rational Transfer Function Based Approach

Korogui, Rubens H.; Fioravanti, Andre R.; Geromel, Jose C.
Fonte: Lavoisier Publicador: Lavoisier
Tipo: Artigo de Revista Científica Formato: 425-436
ENG
Relevância na Pesquisa
36.64%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); The aim of this paper is to present new results on H-infinity control synthesis for time-delay linear systems. We extend the use of a finite order LTI system, called comparison system to H-infinity analysis and design. Differently from what can be viewed as a common feature of other control design methods available in the literature to date, the one presented here treats time-delay systems control design with classical numeric routines based on Riccati equations arisen from H-infinity theory. The proposed algorithm is simple, efficient and easy to implement. Some examples illustrating state and output feedback design are solved and discussed in order to put in evidence the most relevant characteristic of the theoretical results. Moreover, a practical application involving a 3-DOF networked control system is presented.

Dynamics at infinity and other global dynamical aspects of Shimizu-Morioka equations

Messias, Marcelo; Alves Gouveia, Marcio R.; Pessoa, Claudio
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 577-587
ENG
Relevância na Pesquisa
36.45%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); We present some global dynamical aspects of Shimizu-Morioka equations given by(x)Over dot = y, (y)Over dot = x - lambda y - xz, (z)Over dot = -alpha z + x(2),where (x,y,z)aae(3) are the state variables and lambda,alpha are real parameters. This system is a simplified model proposed for studying the dynamics of the well-known Lorenz system for large Rayleigh numbers. Using the Poincar, compactification of a polynomial vector field in ae(3), we give a complete description of the dynamics of Shimizu-Morioka equations at infinity. Then using analytical and numerical tools, we investigate for the case alpha=0 the existence of infinitely many singularly degenerate heteroclinic cycles, each one consisting of an invariant set formed by a line of equilibria together with a heteroclinic orbit connecting two of these equilibria. The dynamical consequences of the existence of these cycles are also investigated. The present study is part of an effort aiming to describe global properties of quadratic three-dimensional vector fields with chaotic dynamical behavior, as made for instance in (Dias et al. in Nonlinear Anal. Real World Appl. 11(5):3491-3500...

Projeto de controladores H-infinito de ordem reduzida e compensação de saturação em estruturas flexíveis; Reduced order H-infinity controller design and saturation compensator in flexible structures

Ruth Vanessa Canahuire Cabello
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 15/07/2014 PT
Relevância na Pesquisa
36.69%
A síntese de controle H-infinito de estruturas flexíveis pode levar à obtenção de controladores de alta ordem. Estes controladores podem apresentar dificuldades para a implementação prática acarretando atrasos de resposta no sistema. Para evitar esse problema, este trabalho apresenta duas sínteses de controladores H-infinito de ordem reduzida por realimentação de saída. Para este propósito, são formulados dois problemas de otimização para a obtenção de controladores de ordem reduzida considerando que as matrizes de estado do controlador estão na forma canônica controlável e canônica modal. As duas sínteses propostas estão baseadas na minimização da norma H-infinito garantindo a estabilidade do sistema em malha fechada. Outro problema considerado neste trabalho são os efeitos de saturação dos atuadores sobre o sistema controlado. A saturação, quando presente no sistema, pode levar a uma perda de desempenho e as vezes à instabilidade da planta. Para tratar o problema de saturação é proposto um problema de otimização baseado no projeto de compensadores anti-windup. A abordagem proposta usa a síntese do problema H-infinito para minimizar diretamente os efeitos do sinal de saturação sobre o sinal de desempenho. Finalmente...

Robust H∞ filtering for networked control systems with markovian jumps and packet dropouts; Robust H-infinity filtering for networked control systems with markovian jumps and packet dropouts

Li, F.; Shi, P.; Wang, X.; Karimi, H.R.
Fonte: Research Council of Norway Publicador: Research Council of Norway
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
36.56%
This paper deals with the H-Infinity filtering problem for uncertain networked control systems. In the study, network-induced delays, limited communication capacity due to signal quantization and packet dropout are all taken into consideration. The finite distributed delays with probability of occurrence in a random way is introduced in the network.The packet dropout is described by a Bernoulli process. The system is modeled as Markovian jumps system with partially known transition probabilities. A full-order filter is designed to estimate the system state. By linear inequality approach, a sufficient condition is derived for the resulting filtering error system to be mean square stable with a prescribed H-Infinity performance level. Finally, a numerical example is given to illustrate the effectiveness and efficiency of the proposed design method.; Fangwen Li, Peng Shi, Xingcheng Wang, Hamid Reza Karimi

El infinito en matemáticas; Infinity in Mathematics

Tessier Núñez, Daniel
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Trabalho de Conclusão de Curso
SPA
Relevância na Pesquisa
36.79%
RESUMEN: Este trabajo pretende ser una reflexión acerca del infinito en matemáticas, abarcando tres aspectos. El primero de ellos sería la descripción del origen y significado del infinito. En el capítulo 1, sección 1.1, reflexionamos sobre el concepto de infinito tanto en el ámbito coloquial como en el histórico y, en el filosófico. En la sección 1.2, nos centramos en aquellos aspectos del infinito relacionados con los números con cardinales, mientras que en la sección 1.3, introducimos el concepto de infinito geométrico relacionado con aquellos puntos que se encuentran indefinidamente lejos. El capítulo 2 trata de responder a dos preguntas que creemos son cruciales: suponiendo que la mayor parte de nuestras preocupaciones versan sobre objetos finitos, ¿es necesario usar el infinito? ¿es coherente? ¿es útil? En la sección 2.1 se responde afirmativamente a esta cuestión sobre su utilidad. Así se muestra cómo algunos hechos que no involucran sino aspectos finitos tienen propiedades que puedes demostrarse tanto con el uso del infinito como de manera finitista (números de catalán,...). También en esta misma sección vemos otro ejemplo de la serie de Goodstein y, el teorema 1, que afirma que en dicha serie se alcanza después de un número finito de etapas el valor 0...

Principal infinity-bundles - General theory

Nikolaus, Thomas; Schreiber, Urs; Stevenson, Danny
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/07/2012
Relevância na Pesquisa
26.9%
The theory of principal bundles makes sense in any infinity-topos, such as that of topological, of smooth, or of otherwise geometric infinity-groupoids/infinity-stacks, and more generally in slices of these. It provides a natural geometric model for structured higher nonabelian cohomology and controls general fiber bundles in terms of associated bundles. For suitable choices of structure infinity-group G these G-principal infinity-bundles reproduce the theories of ordinary principal bundles, of bundle gerbes/principal 2-bundles and of bundle 2-gerbes and generalize these to their further higher and equivariant analogs. The induced associated infinity-bundles subsume the notions of gerbes and higher gerbes in the literature. We discuss here this general theory of principal infinity-bundles, intimately related to the axioms of Giraud, Toen-Vezzosi, Rezk and Lurie that characterize infinity-toposes. We show a natural equivalence between principal infinity-bundles and intrinsic nonabelian cocycles, implying the classification of principal infinity-bundles by nonabelian sheaf hyper-cohomology. We observe that the theory of geometric fiber infinity-bundles associated to principal infinity-bundles subsumes a theory of infinity-gerbes and of twisted infinity-bundles...

An introduction to C-infinity schemes and C-infinity algebraic geometry

Joyce, Dominic
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.87%
This is a survey of the author's paper arXiv:1001.0023 on "Algebraic Geometry over C-infinity rings". If X is a smooth manifold then the R-algebra C^\infty(X) of smooth functions c : X --> R is a "C-infinity ring". That is, for each smooth function f : R^n --> R there is an n-fold operation \Phi_f : C^\infty(X)^n --> C^\infty(X) acting by \Phi_f: (c_1,...,c_n) |--> f(c_1,...,c_n), and these operations \Phi_f satisfy many natural identities. Thus, C^\infty(X) actually has a far richer structure than the obvious R-algebra structure. We explain a version of algebraic geometry in which rings or algebras are replaced by C-infinity rings. As schemes are the basic objects in algebraic geometry, the new basic objects are "C-infinity schemes", a category of geometric objects generalizing manifolds, and whose morphisms generalize smooth maps. We also discuss "C-infinity stacks", including Deligne-Mumford C-infinity stacks, a 2-category of geometric objects generalizing orbifolds. We study quasicoherent and coherent sheaves on C-infinity schemes and C-infinity stacks, and orbifold strata of Deligne-Mumford C-infinity stacks. This enables us to use the tools of algebraic geometry in differential geometry, and to describe singular spaces such as moduli spaces occurring in differential geometric problems. Many of these ideas are not new: C-infinity rings and C-infinity schemes have long been part of synthetic differential geometry. But we develop them in new directions. In a new book...

H-Infinity controller design for structural damping

Rowen, Darren; Hopkins, Mark
Fonte: SPIE Publicador: SPIE
Tipo: Proceedings
EN_US
Relevância na Pesquisa
36.56%
This paper describes a multivariable controller design procedure that uses mixed-sensitivity H-infinity control theory. The design procedure is based on the assumption that structural noise can be modeled as entering a state-space system through a random input matrix. The design process starts with a full-order flexible state-space model that undergoes a frequency-weighted balanced truncation to obtain a reduced-order model with excellent low frequency matching. Weighting functions are then created to specify the desired frequency range for disturbance rejection and controller bandwidth. A structural noise input matrix is also designed to identify system modes where maximal damping is desired. An augmented plant is then assembled using the reduced-order model, weighting functions and structural noise input matrix to create a mixed-sensitivity configuration. A state-space controller is then realized using an H-infinity design algorithm. A two-input, three-output, doubly cantilevered beam system provides a design example. A 174th-order, discrete-time, state-space model of the cantilevered beam system was used to generate a reduced 40th-order model. A 55th-order Hinfinity controller was then designed with a controller bandwidth of approximately 300 Hz. This non-square modern controller uses feedback signals from two piezoelectric sensors...

Drift to Infinity and the Strong Law for Subordinated Random Walks and Levy Processes

Erickson, K Bruce; Maller, Ross
Fonte: Plenum Publishing Corporation Publicador: Plenum Publishing Corporation
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.56%
We determine conditions under which a subordinated random walk of the form S⌊ N(n)⌋ tends to infinity almost surely (a.s), or S⌊ N(n)⌋/n tends to infinity a.s., where {N(n)} is a (not necessarily integer valued) renewal process, ⌊ N(n)⌋} denot

FORMALIZATION AND INFINITY

Porto, André
Fonte: UNICAMP-CLE-Publicações Publicador: UNICAMP-CLE-Publicações
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares; Formato: application/pdf
Publicado em 11/12/2015 POR
Relevância na Pesquisa
36.45%
This article discusses some of Chateaubriand’s views on the connections between the ideas of formalization and infinity, as presented in chapters 19 and 20 of Logical Forms. We basically agree with his criticisms of the standard construal of these connections, a view we named “formal proofs as ultimate provings”, but we suggest an alternative way of picturing that connection based on some ideas of the late Wittgenstein. Resumo:Este artigo analisa algumas das propostas de Chateaubriand sobre a conexão entre as idéias de formalização e infinitude, da maneira com elas aparecem nos capítulos 19 e 20 de Logical Forms. Basicamente concordamos com suas críticas à forma usual de se entender essas conexões, uma concepção que chamamos de “provas formais como demonstrações supremas”, mas ainda sugerimos uma concepção alternativa dessa conexão baseada em algumas idéias do Wittgenstein tardio.Palavras chave: Chateaubriand. Provas. Formalização. Infinitude. Finitismo estrito