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Estudo do fenômeno da auto-intersecção em um anel anisotrópico; Study of the self-intersection anomaly in an anisotropic ring

García Sánchez, Jesús Antonio
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 17/11/2008 PT
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Estuda-se numericamente uma placa circular homogênea com furo centrado sob estado plano de deformação. A placa está fixa ao longo do contorno interno e está sob compressão radial uniforme ao longo do contorno externo. O material da placa é elástico-linear e anisotrópico. Apresenta-se a solução analítica do problema, a qual satisfaz as equações governantes de equilíbrio, no contexto da elasticidade linear clássica. Esta solução prediz o comportamento espúrio da auto-intersecção em uma região central da placa. Para evitar este comportamento, utiliza-se uma teoria que propõe encontrar um campo de deslocamento que minimize a energia potencial total do corpo sujeito à restrição de injetividade local para o campo da deformação correspondente. Esta teoria, juntamente com o método das penalidades interiores, permite encontrar uma solução numérica que preserva a injetividade. Esta solução corresponde a um campo de deslocamento radialmente simétrico. Estuda-se a possibilidade de encontrar uma solução rotacionalmente simétrica do problema restrito, em que o campo de deslocamento possua as componentes radial e tangencial, ambas funções somente do raio. Os resultados desta última modelagem mostram que a componente tangencial é nula...

Differential geometry of intersection curves in R(4) of three implicit surfaces

Alessio, Osmar
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 455-471
ENG
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We present algorithms for computing the differential geometry properties of intersection Curves of three implicit surfaces in R(4), using the implicit function theorem and generalizing the method of X. Ye and T. Maekawa for 4-dimension. We derive t, n, b(1), b(2) vectors and curvatures (k(1), k(2), k(3)) for transversal intersections of the intersection problem. (C) 2008 Elsevier B.V. All rights reserved.

Algorithm to determine the intersection curves between bezier surfaces by the solution of multivariable polynomial system and the differential marching method

Faustini,Mário Carneiro; Tsuzuki,Marcos Sales Guerra
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2000 EN
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The determination of the intersection curve between Bézier Surfaces may be seen as the composition of two separated problems: determining initial points and tracing the intersection curve from these points. The Bézier Surface is represented by a parametric function (polynomial with two variables) that maps a point in the tridimensional space from the bidimensional parametric space. In this article, it is proposed an algorithm to determine the initial points of the intersection curve of Bézier Surfaces, based on the solution of polynomial systems with the Projected Polyhedral Method, followed by a method for tracing the intersection curves (Marching Method with differential equations). In order to allow the use of the Projected Polyhedral Method, the equations of the system must be represented in terms of the Bernstein basis, and towards this goal it is proposed a robust and reliable algorithm to exactly transform a multivariable polynomial in terms of power basis to a polynomial written in terms of Bernstein basis .

Local intersection volume (LIV) descriptors: 3D-QSAR models for PGI2 receptor ligands

Martins,Rita C. A.; Albuquerque,Magaly G.; Alencastro,Ricardo B.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2002 EN
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Prostacyclin I2 inhibits platelet aggregation through specific binding to its membrane receptor. In this work, we developed 3D-QSAR models for a series of aromatic heterocyclic compounds from literature using the local intersection volume descriptor. The models obtained can be applied to design new PGI2 receptor ligands with potential platelet anti-aggregating activity.

The Intersection Complex as a Weight Truncation and an Application to Shimura Varieties

Morel, Sophie Marguerite
Fonte: World Scientific Publishing Company Publicador: World Scientific Publishing Company
Tipo: Monograph or Book
EN_US
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The purpose of this talk is to present an (apparently) new way to look at the intersection complex of a singular variety over a finite field, or, more generally, at the intermediate extension functor on pure perverse sheaves, and an application of this to the cohomology of noncompact Shimura varieties.; Mathematics

Algorithms and Data Structures for an Expanded Family of Matroid Intersection Problems

Frederickson, Greg N. ; Srinivas, Mandayam A.
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
ENG
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Consider a matroid of rank n in which each element has a real-valued cost and one of d > 1 colors. A class of matroid intersection problems is studied in which one of the matroids is a partition matroid that specifies that a base have qj elements of color j, for j = 1, 2, ... , d. Relationships are characterized among the solutions to the family of problems generated when the vector (q1, q2, ... , qd) is allowed to range over all values that sum to n. A fast algorithm is given for solving such matroid intersection problems when d is small. A characterization is presented for how the solution changes when one element changes in cost. Data structures are given for updating the solution on-line each time the cost of an arbitrary matroid element is modified. Efficient update algorithms are given for maintaining a color-constrained minimum spanning tree in either a general or a planar graph. An application of the techniques to finding a minimum spanning tree with several degree-constrained vertices is described.

Privacy preserving set intersection based on bilinear groups

Sang, Y.; Shen, H.
Fonte: Australian Computer Society; Sydney Publicador: Australian Computer Society; Sydney
Tipo: Conference paper
Publicado em //2008 EN
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We propose a more efficient privacy preserving set intersection protocol which improves the previously known result by a factor of O(N) in both the computation and communication complexities (N is the number of parties in the protocol). Our protocol is obtained in the malicious model, in which we assume a probabilistic polynomial-time bounded adversary actively controls a fixed set of t (t < N/2) parties. We use a (t + 1,N)-threshold version of the Boneh-Goh-Nissim (BGN) cryptosystem whose underlying group supports bilinear maps. The BGN cryptosystem is generally used in applications where the plaintext space should be small, because there is still a Discrete Logarithm (DL) problem after the decryption. In our protocol the plaintext space can be as large as bounded by the security parameter τ, and the intractability of DL problem is utilized to protect the private datasets. Based on the bilinear map, we also construct some efficient non-interactive proofs. The security of our protocol can be reduced to the common intractable problems including the random oracle, subgroup decision and discrete logarithm problems. The computation complexity of our protocol is O(NS2τ3) (S is the cardinality of each party's dataset), and the communication complexity is O(NS2τ) bits. A similar work by Kissner et al. (2006) needs O(N2S2τ3) computation complexity and O(N2S2τ) communication complexity for the same level of correctness as ours.; Yingpeng Sang...

Intersection : Exploration du concept à travers la composition de trois oeuvres musicales

Moore, Stephanie
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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Dans mon travail de recherche et de création musicale, je m’inspire du concept d’intersection pour sa capacité à donner naissance à quelque chose de nouveau. Ce mémoire de maîtrise documente une exploration de ce concept dans trois contextes différents : une pièce instrumentale, une pièce mixte et une pièce pour chœur. J’emploie le mot « intersection » dans le sens figuré de deux éléments abstraits ou concrets qui se rencontrent. La nature de leur rencontre ainsi que les résultats possibles m’intéressent également. Je vise l’intégration du concept à tous les niveaux d’une pièce : du global (la conception, la forme) jusqu’au local (la facture et l’emploi des techniques de composition). Le choix de procédés est très ouvert et dépend entièrement du contexte de la pièce et du résultat artistique envisagé. Ainsi, dans chacune de mes trois pièces de maîtrise, j’ai choisi une approche différente de l’idée de l’intersection. J’ai expérimenté une variété de moyens et de procédés, ainsi que la fonction de la composante extra-musicale (lorsqu’il y en a une). Au premier chapitre, je discute de mon quintette Finding Common Ground qui explore l’intersection de l’écriture pour percussion avec l’écriture pour les quatre autres instruments plutôt « mélodiques ». Ensuite...

Intersection local times of independent Brownian motions as generalized white noise functionals

Albeverio, Sergio; Oliveira, Maria João; Streit, Ludwig
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
Publicado em //2001 ENG
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The original publication is available at http://www.springerlink.com/content/14jtbl19nh37ggtx/fulltext.pdf; A "chaos expansion" of the intersection local time functional of two independent Brownian motions in Rd is given. The expansion is in terms of normal products of white noise (corresponding to multiple Wiener integrals). As a consequence of the local structure of the normal products, the kernel functions in the expansion are explicitly given and exhibit clearly the dimension dependent singularities of the local time functional. Their Lp-properties are discussed. An important tool for deriving the chaos expansion is a computation of the "S-transform" of the corresponding regularized intersection local times and a control about their singular limit.; peerreviewed

Metodos computacionais para determinação de pontos de intersecção de n esferas no 'R POT. N'; Computacional methods for determination of points of intersection of n sphere in 'R POT. N'

Marcos Roberto da Silva Gonçalves
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/07/2008 PT
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Neste trabalho, abordamos o problema da determinação de pontos de intersecção de n esferas no Rn. Este problema, além de ser importante matematicamente, é um problema com muitas aplicações, que vão desde a localização de pontos no globo, pelo sistema GPS, até a posicionamento de átomos em estruturas moleculares. O problema de encontrar a intersecção de n esferas no Rn é, em geral, formulado como um conjunto de n equações não-lineares, onde se deseja determinar a sua solução através de um método eficiente e confiável. Mostramos que, com exceção de alguns casos, o problema é geralmente resolvido de forma eficaz, empregando técnicas de álgebra linear. Reformulamos o problema de forma a convertê-lo em um problema linear e apresentamos dois métodos baseados na decomposição de matrizes. Testamos os métodos para casos particulares de baixa dimensão, analisando o custo computacional e possíveis dificuldades que podem surgir devido a erros de medição; We consider the problem of determining the points of intersection of n spheres in R n. This problem has many applications, such as the location of points on the globe by the GPS system and problems related to molecular geometry optimization. The problem of finding the intersection of n spheres in R n is generally expressed as a set of nonlinear equations...

Intersection Cohomology. Simplicial Blow-up and Rational Homotopy

Chataur, David; Saralegi-Aranguren, Martintxo; Tanré, Daniel
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Let X be a pseudomanifold. In this text, we use a simplicial blow-up to define a cochain complex whose cohomology with coefficients in a field, is isomorphic to the intersection cohomology of X, introduced by M. Goresky and R. MacPherson. We do it simplicially in the setting of a filtered version of face sets, also called simplicial sets without degeneracies, in the sense of C.P. Rourke and B.J. Sanderson. We define perverse local systems over filtered face sets and intersection cohomology with coefficients in a perverse local system. In particular, as announced above when X is a pseudomanifold, we get a perverse local system of cochains quasi-isomorphic to the intersection cochains of Goresky and MacPherson, over a field. We show also that these two complexes of cochains are quasi-isomorphic to a filtered version of Sullivan's differential forms over the field Q. In a second step, we use these forms to extend Sullivan's presentation of rational homotopy type to intersection cohomology. For that, we construct a functor from the category of filtered face sets to a category of perverse commutative differential graded Q-algebras (cdga's) due to Hovey. We establish also the existence and unicity of a positively graded, minimal model of some perverse cdga's...

Tropical Intersection Theory from Toric Varieties

Katz, Eric
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/07/2009
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We apply ideas from intersection theory on toric varieties to tropical intersection theory. We introduce mixed Minkowski weights on toric varieties which interpolate between equivariant and ordinary Chow cohomology classes on complete toric varieties. These objects fit into the framework of tropical intersection theory developed by Allermann and Rau. Standard facts about intersection theory on toric varieties are applied to show that the definitions of tropical intersection product on tropical cycles in $\R^n$ given by Allermann-Rau and Mikhalkin are equivalent. We introduce an induced tropical intersection theory on subvarieties on a toric variety. This gives a conceptional proof that the intersection of tropical $\psi$-classes on $\cmbar_{0,n}$ used by Kerber and Markwig computes classical intersection numbers.

Regularity of Intersection Local Times of Fractional Brownian Motions

Wu, Dongsheng; Xiao, Yimin
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/04/2009
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Let $B^{\alpha_i}$ be an $(N_i,d)$-fractional Brownian motion with Hurst index ${\alpha_i}$ ($i=1,2$), and let $B^{\alpha_1}$ and $B^{\alpha_2}$ be independent. We prove that, if $\frac{N_1}{\alpha_1}+\frac{N_2}{\alpha_2}>d$, then the intersection local times of $B^{\alpha_1}$ and $B^{\alpha_2}$ exist, and have a continuous version. We also establish H\"{o}lder conditions for the intersection local times and determine the Hausdorff and packing dimensions of the sets of intersection times and intersection points. One of the main motivations of this paper is from the results of Nualart and Ortiz-Latorre ({\it J. Theor. Probab.} {\bf 20} (2007)), where the existence of the intersection local times of two independent $(1,d)$-fractional Brownian motions with the same Hurst index was studied by using a different method. Our results show that anisotropy brings subtle differences into the analytic properties of the intersection local times as well as rich geometric structures into the sets of intersection times and intersection points.; Comment: 27 pages

Combinatorial Intersection Cohomology for Fans

Barthel, Gottfried; Brasselet, Jean-Paul; Fieseler, Karl-Heinz; Kaup, Ludger
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/02/2000
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We continue the approach toward a purely combinatorial "virtual" intersection cohomology for possibly non-rational fans, based on our investigation of equivariant intersection cohomology for toric varieties (see math.AG/9904159). Fundamental objects of study are "minimal extension sheaves" on "fan spaces". These are flabby sheaves of graded modules over a sheaf of polynomial rings, satisfying three relatively simple axioms that characterize the properties of the equivariant intersection cohomology sheaf on a toric variety, endowed with the finite topology given by open invariant subsets. These sheaves are models for the "pure" objects of a "perverse category"; a "Decomposition Theorem" is shown to hold. -- Formalizing those fans that define "equivariantly formal" toric varieties (where equivariant and non-equivariant intersection cohomology determine each other by Kunneth type formulae), we study "quasi-convex" fans (including fans with convex or with "co-convex" support). For these, there is a meaningful "virtual intersection cohomology". We characterize quasi-convex fans by a topological condition on the support of their boundary fan and prove a generalization of Stanley's "Local-Global" formula realizing the intersection Poincare polynomial of a complete toric variety in terms of local data. Virtual intersection cohomology of quasi-convex fans is shown to satify Poincare duality. To describe the local data in terms of virtual intersection cohomology of lower-dimensional complete polytopal fans...

On $k$-connectivity and minimum vertex degree in random $s$-intersection graphs

Zhao, Jun; Yağan, Osman; Gligor, Virgil
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Random $s$-intersection graphs have recently received much interest in a wide range of application areas. Broadly speaking, a random $s$-intersection graph is constructed by first assigning each vertex a set of items in some random manner, and then putting an undirected edge between all pairs of vertices that share at least $s$ items (the graph is called a random intersection graph when $s=1$). A special case of particular interest is a uniform random $s$-intersection graph, where each vertex independently selects the same number of items uniformly at random from a common item pool. Another important case is a binomial random $s$-intersection graph, where each item from a pool is independently assigned to each vertex with the same probability. Both models have found numerous applications thus far including cryptanalysis, and the modeling of recommender systems, secure sensor networks, online social networks, trust networks and small-world networks (uniform random $s$-intersection graphs), as well as clustering analysis, classification, and the design of integrated circuits (binomial random $s$-intersection graphs). In this paper, for binomial/uniform random $s$-intersection graphs, we present results related to $k$-connectivity and minimum vertex degree. Specifically...

Toroidality and projective-planarity of intersection graphs of subgroups of finite groups

Rajkumar, R.; Devi, P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Let $G$ be a group. The intersection graph of subgroups of $G$, denoted by $\mathscr{I}(G)$, is a graph with all the proper subgroups of $G$ as its vertices and two distinct vertices in $\mathscr{I}(G)$ are adjacent if and only if the corresponding subgroups having a non-trivial intersection in $G$. In this paper, we classify the finite groups whose intersection graph of subgroups are toroidal or projective-planar. In addition, we classify the finite groups whose intersection graph of subgroups are one of bipartite, complete bipartite, tree, star graph, unicyclic, acyclic, cycle, path or totally disconnected. Also we classify the finite groups whose intersection graph of subgroups does not contain one of $K_5$, $K_4$, $C_5$, $C_4$, $P_4$, $P_3$, $P_2$, $K_{1,3}$, $K_{2,3}$ or $K_{1,4}$ as a subgraph. We estimate the girth of the intersection graph of subgroups of finite groups. Moreover, we characterize some finite groups by using their intersection graphs. Finally, we obtain the clique cover number of the intersection graph of subgroups of groups and show that intersection graph of subgroups of groups are weakly $\alpha$-perfect.; Comment: 38 pages, 10 figures. arXiv admin note: text overlap with arXiv:1505.03462, some corrections made

Analyzing Stratified Spaces Using Persistent Versions of Intersection and Local Homology

Bendich, Paul
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 797394 bytes; application/pdf
Publicado em 05/08/2008 EN_US
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This dissertation places intersection homology and local homology within the framework of persistence, which was originally developed for ordinary homology by Edelsbrunner, Letscher, and Zomorodian. The eventual goal, begun but not completed here, is to provide analytical tools for the study of embedded stratified spaces, as well as for high-dimensional and possibly noisy datasets for which the number of degrees of freedom may vary across the parameter space. Specifically, we create a theory of persistent intersection homology for a filtered stratified space and prove several structural theorems about the pair groups asso- ciated to such a filtration. We prove the correctness of a cubic algorithm which computes these pair groups in a simplicial setting. We also define a series of intersec- tion homology elevation functions for an embedded stratified space and characterize their local maxima in dimension one. In addition, we develop a theory of persistence for a multi-scale analogue of the local homology groups of a stratified space at a point. This takes the form of a series of local homology vineyards which allow one to assess the homological structure within a one-parameter family of neighborhoods of the point. Under the assumption of dense sampling...

Triangle-Triangle Intersection Determination and Classification to Support Qualitative Spatial Reasoning

Sabharwal,Chaman L.; Leopold,Jennifer L.; McGeehan,Douglas
Fonte: Instituto Politécnico Nacional, Centro de Innovación y Desarrollo Tecnológico en Cómputo Publicador: Instituto Politécnico Nacional, Centro de Innovación y Desarrollo Tecnológico en Cómputo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
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In CAD/CAM modeling, objects are represented using the Boundary Representation (ANSI Brep) model Detection of possible intersection between objects can be based on the objects' boundaries (ie., triangulated surfaces), and computed using triangle-triangle intersection. Usually only a cross intersection algorithm is needed; however, it is beneficial to have a single robust and fast intersection detection algorithm for both cross and coplanar intersections. For qualitative spatial reasoning, a general-purpose algorithm is desirable for accurately differentiating the relations in a region connection calculus, a task that requires consideration of intersection between objects. Herein we present a complete uniform integrated algorithm for both cross and coplanar intersection. Additionally, we present parametric methods for classifying and computing intersection points. This work is applicable to most region connection calculi, particularly VRCC-3D+, which detects intersections between 3D objects as well as their projections in 2D that are essential for occlusion detection.

Selection of MOSFET Sizes by Fuzzy Sets Intersection in the Feasible Solutions Space

Polanco-Martagón,S.; Reyes-Salgado,G.; Flores-Becerra,G.; Tlelo-Cuautle,E.; Fraga,L.G. de la; Guerra-Gómez,I.; Duarte-Villaseñor,M.A.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
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A fuzzy sets intersection procedure to select the optimum sizes of analog circuits composed of metal-oxide-semiconductor field-effect-transistors (MOSFETs), is presented. The cases of study are voltage followers (VFs) and a current-feedback operational amplifier (CFOA), where the width (W) and length (L) of the MOSFETs are selected from the space of feasible solutions computed by swarm or evolutionary algorithms. The evaluation of three objectives, namely: gain, bandwidth and power consumption; is performed using HSPICE™ with standard integrated circuit (IC) technology of 0.35um for the VFs and 180nm for the CFOA. Therefore, the intersection procedure among three fuzzy sets representing "gain close to unity", "high bandwidth" and "minimum power consumption", is presented. The main advantage relies on its usefulness to select feasible W/L sizes automatically but by considering deviation percentages from the desired target specifications. Basically, assigning a threshold to each fuzzy set does it. As a result, the proposed approach selects the best feasible sizes solutions to guarantee and to enhance the performances of the ICs in analog signal processing applications.

Analysing delay and queue length using microscopic simulation for the unconventional intersection design Superstreet

Naghawi,H H; Idewu,W I A
Fonte: Journal of the South African Institution of Civil Engineering Publicador: Journal of the South African Institution of Civil Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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With the increasing demand on today's roadway systems, intersections are beginning to fail at alarming rates prior to the end of their design periods. Therefore, maintaining safety and operational efficiency at intersections on arterial roadways remains a constant goal. This effort for sustainability has spawned the creation and evaluation of numerous types of unconventional intersection designs. Several unconventional designs exist and have been studied, including the Bowtie, Continuous Flow Intersection, Paired Intersection, Jughandle, Median U-Turn, Single Quadrant Roadway and Superstreet Median. Typically, these designs eliminate/reroute conflicting left-turn manoeuvres to and from the minor or collector cross road. High left-turning volumes are addressed by adding an exclusive left-turning signal. This consequently increases the required number of signal phases and shorter green time for the major through traffic. This paper describes the evaluation of an unconventional intersection designed to lessen the effects of high left-turning traffic. To aid in the evaluation of the unconventional Superstreet design, a comparison of a Conventional intersection's operation was made. Constructing and analysing a live Superstreet and Conventional intersection design is a massive undertaking. Microscopic traffic models were developed and tested using CORSIM. A variety of scenarios were created by changing the approach volumes and turning percentages on the major/minor roads to reflect different congestion levels that may occur at the intersection on any given day. The total number of created scenarios was 72...