MATEMÁTICA
INTERACÇÃO ENTRE FACTORES ANINHADOS
Ramos, Paulo José Raimundo
Orientadores: João Tiago Praça Nunes Mexia e Dário Jorge da Conceição Ferreira Grau Concedido por: Universidade da Beira Interior
Doutoramento em: Matemática
Provas Concluídas em : 02 de Julho de 2009 Tipo de documento: Tese
Resumo: Nesta dissertação usaremos operações binárias sobre Álgebras de Jordan Comutativas, AJC, para estudar interacções entre factores que aninham. É de salientar que a partir de duas AJC se pode,
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mediante essas operações binárias, construir AJC que constituem uma Álgebra de Boole. Assim quando se aninham os tratamentos dum modelo em cada um dos tratamentos dum outro modelo poder- se-á estudar quais os conjuntos de factores do modelo aninhado para os quais se consideram interacções com os factores do outro modelo.
Mostraremos ainda como obter estatísticas suficientes e completas que permitem realizar a inferência. __________________________________________________________________________________
JOGOS MATEMÁTICOS, A PORTUGUESE PROJECT Carvalho, A.a ; Santos, C.P.b; Neto, J.c; Silva, .N.c
aISEL, Inst Super Engn Lisboa, Área Departamental de Matemática, P-1959-007 Lisbon, Portugal bInstituto Superior de Educação e Ciências, Lisboa, Portugal
cFaculdade de Ciências da Universidade de Lisboa, Portugal
Editor: Associação Ludus, Proceedings: Board Game Studies Colloquium XI, pp. 1-204, 2009 ISBN: 978-989-95878-5-4
Tipo de Documento: Communication
Resumo: Ludus Association and other mathematical associations organize yearly the Portuguese Championship of Mathematical Games. Since 2004, this tournament has been growing: from 500 students in 2004 in Lisbon to 1200 students in 2009 in Covilhã. Students aged 7 to 17, from all the country, join, each year, at a Portuguese city to play one of six different abstract games.
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KNEADING THEORY ANALYSIS OF THE DUFFING EQUATION Caneco, A.a; Gracio, C.b,c; Rocha, J.L.d
aISEL, Inst Super Engn Lisboa, DEETC, Math Unit, P-1959-007 Lisbon, Portugal bUniv Evora, Dept Math, P-7000671 Evora, Portugal
cCIMA UE, P-7000671 Evora, Portugal
dISEL, Inst Super Engn Lisboa, DEQ, Math Unit, P-1959-007 Lisbon, Portugal
Fonte: Chaos Solitons & Fractals, 42 (3): 1529-1538, NOV 15 2009 ISSN: 0960-0779
DOI: 10.1016/j.chaos.2009.03.040 Editor: Pergamon-Elsevier Science Ltd
Área Científica: Mathematics, Interdisciplinary Applications; Physics, Multidisciplinary; Physics, Mathematical
Resumo: The purpose of this paper is to study the symmetry effect on the kneading theory for symmetric unimodal maps and for symmetric bimodal maps, We obtain some properties about the kneading determinant for these maps, that implies some simplifications in the usual formula to compute, explicitly, the topological entropy. As an application, we study the chaotic behaviour of the two-well Duffing equation with forcing.
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LIMITING INTERNAL SUPPLY VOLTAGE SPIKES IN DC-DC CONVERTERS Rocha, J.a; Santos, M.b; Santos, G.c; Monteiro, A.d; Neves, A.e; Braga, P.f
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aISEL, Inst Super Engn Lisboa, P-1959-007 Lisbon, Portugal
bDept. Interactive Digital Telev., Pontifical Catholic Univ. of Minas Gerais, Pocos de Caldas, Brasil cDept. of Comput. Sci., Santa Catarina State Univ. (UDESC), Joinville, Brasil
dAES-Eletropaulo, Sao Paulo, Brasil eIEETA, Univ. de Aveiro, Aveiro, Portugal fPernambuco State Univ., Recife, Brasil
Fonte: ISIE: 2009 IEEE International Symposium on Industrial Electronics: 1049-1054 2009
Conferência: IEEE International Symposium on Industrial Electronics (ISIE 2009), Seoul, South Korea, Jul 05-08, 2009
ISBN: 978-1-4244-4347-5 Editor: IEEE
Tipo de Documento: Proceeding Paper
Área Científica: Engineering, Electrical & Electronic
URL: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5222413&tag=1
Resumo: Implementing monolithic DC-DC converters for low power portable applications with a standard low voltage CMOS technology leads to lower production costs and higher reliability. Moreover, it allows miniaturization by the integration of two units in the same die: the power management unit that regulates the supply voltage for the second unit, a dedicated signal processor, that performs the functions required. This paper presents original techniques that limit spikes in the internal supply voltage on a monolithic DC-DC converter, extending the use of the same technology for both units. These spikes are mainly caused by fast current variations in the path connecting the external power supply to the internal pads of the converter power block. This path includes two parasitic inductances inbuilt in bond wires and in package pins. Although these parasitic inductances present relative low values when compared with the typical external inductances of DC-DC converters, their effects can not be neglected when switching high currents at high switching frequency. The associated overvoltage frequently causes destruction, reliability problems and/or control malfunction. Different spike reduction techniques are presented and compared. The proposed techniques were used in the design of the gate driver of a DC-DC converter included in a power management unit implemented in a standard 0.35 mu m CMOS technology.
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MEASURING AND CONTROLLING THE CHAOTIC MOTION OF PROFITS Januario, C.a; Gracio, C.b,d; Mendes, D.A.c; Duarte, J.a,d
aISEL, Inst Super Engn Lisboa, Dept Chem, Math Unit, P-1959-007 Lisbon, Portugal bUniv Evora, Dept Math, P-7000585 Evora, Portugal
cInst Super Ciencias Trabalho & Empresa, Dept Quantitat Methods, P-1649026 Lisbon, Portugal dUniv Evora, CIMA UE, P-7000585 Evora, Portugal
Fonte: International Journal of Bifurcation and Chaos, 19 (11): 3593-3604, Nov 2009 ISSN: 0218-1274
DOI: 10.1142/S021812740902502X Editor: World Scientific Publ CO Pte Ltd Tipo de Documento: Review
Área Científica: Mathematics, Interdisciplinary Applications; Multidisciplinary Sciences
Resumo: The study of economic systems has generated deep interest in exploring the complexity of chaotic motions in economy. Due to important developments in nonlinear dynamics, the last two
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decades have witnessed strong revival of interest in nonlinear endogenous business chaotic models. The inability to predict the behavior of dynamical systems in the presence of chaos suggests the application of chaos control methods, when we are more interested in obtaining regular behavior. In the present article, we study a specific economic model from the literature. More precisely, a system of three ordinary differential equations gather the variables of profits, reinvestments and financial flow of borrowings in the structure of a firm. Firstly, using results of symbolic dynamics, we characterize the topological entropy and the parameter space ordering of kneading sequences, associated with one- dimensional maps that reproduce significant aspects of the model dynamics. The analysis of the variation of this numerical invariant, in some realistic system parameter region, allows us to quantify and to distinguish different chaotic regimes. Finally, we show that complicated behavior arising from the chaotic firm model can be controlled without changing its original properties and the dynamics can be turned into the desired attracting time periodic motion (a stable steady state or into a regular cycle). The orbit stabilization is illustrated by the application of a feedback control technique initially developed by Romeiras et al. [1992]. This work provides another illustration of how our understanding of economic models can be enhanced by the theoretical and numerical investigation of nonlinear dynamical systems modeled by ordinary differential equations.
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MEASURING COMPLEXITY IN A BUSINESS CYCLE MODEL OF THE KALDOR TYPE