The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Michael Scott - One of the best experts on this subject based on the ideXlab platform.
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endomorphisms for faster elliptic curve cryptography on a large class of curves
Journal of Cryptology, 2011Co-Authors: Steven D Galbraith, Xibin Lin, Michael ScottAbstract:Efficiently computable homomorphisms allow elliptic curve point multiplication to be accelerated using the Gallant–Lambert–Vanstone (GLV) method. Iijima, Matsuo, Chao and Tsujii gave such homomorphisms for a large class of elliptic curves by working over ${\mathbb{F}}_{p^{2}}$. We extend their results and demonstrate that they can be applied to the GLV method. In general we expect our method to require about 0.75 the time of previous best methods (except for subfield curves, for which Frobenius expansions can be used). We give detailed implementation results which show that the method runs in between 0.70 and 0.83 the time of the previous best methods for elliptic curve point multiplication on general curves.
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endomorphisms for faster elliptic curve cryptography on a large class of curves
International Cryptology Conference, 2009Co-Authors: Steven D Galbraith, Xibin Lin, Michael ScottAbstract:Efficiently computable homomorphisms allow elliptic curve point multiplication to be accelerated using the Gallant-Lambert- Vanstone (GLV) method. We extend results of Iijima, Matsuo, Chao and Tsujii which give such homomorphisms for a large class of elliptic curves by working over ${\mathbb F}_{p^2}$ and demonstrate that these results can be applied to the GLV method. In general we expect our method to require about 0.75 the time of previous best methods (except for subfield curves, for which Frobenius expansions can be used). We give detailed implementation results which show that the method runs in between 0.70 and 0.84 the time of the previous best methods for elliptic curve point multiplication on general curves.
Jian Liu - One of the best experts on this subject based on the ideXlab platform.
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computation of medial axis and offset curves of curved boundaries in planar domains based on the cesaro s approach
Computer Aided Geometric Design, 2009Co-Authors: Lixin Cao, Zhenyuan Jia, Jian LiuAbstract:In this paper, we begin our research from the generating theory of the medial axis. The normal equidistant mapping relationships between the two boundaries and the medial axis have been proposed based on the moving Frenet frames and Cesaro's approach of the differential geometry. Two pairs of adjoint curves have been formed and the geometrical model of the medial axis transform of the planar domains with curved boundaries has been established. The relations of position mapping, scale transform and differential invariants between the curved boundaries and the medial axis have been investigated. Based on this model, a tracing algorithm for the computation of the medial axis has been generated. This algorithm overcomes the topological singularity of the polygon approximation algorithms by using exact curved boundaries, and doesn't need iteration. So, it can be used for the computation of the medial axis effectively and accurately. Based on the medial axis transform and the envelope theory, the trimmed offset curves of curved boundaries have been investigated. Several numerical examples are given at the end of the paper.
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computation of medial axis and offset curves of curved boundaries in planar domain
Computer-aided Design, 2008Co-Authors: Lixin Cao, Jian LiuAbstract:In this paper, we begin our research from the generating theory of the medial axis. The normal equidistant mapping relationships between two boundaries and its medial axis have been proposed based on the moving Frenet frames and Cesaro's approach of the differential geometry. Two pairs of adjoint curves have been formed and the geometrical model of the medial axis transform of the planar domains with curved boundaries has been established. The relations of position mapping, scale transform and differential invariants between the curved boundaries and the medial axis have been investigated. Based on this model, a tracing algorithm for the computation of the medial axis has been generated. In order to get the accurate medial axis and branch points, a Two_Tangent_Points_Circle algorithm and a Three_Tangent_Points_Circle algorithm have been generated, which use the results of the tracing algorithm as the initial values to make the iterative process effective. These algorithms can be used for the computation of the medial axis effectively and accurately. Based on the medial axis transform and the envelope theory, the trimmed offset curves of curved boundaries have been investigated. Several numerical examples are given at the end of the paper.
Steven D Galbraith - One of the best experts on this subject based on the ideXlab platform.
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endomorphisms for faster elliptic curve cryptography on a large class of curves
Journal of Cryptology, 2011Co-Authors: Steven D Galbraith, Xibin Lin, Michael ScottAbstract:Efficiently computable homomorphisms allow elliptic curve point multiplication to be accelerated using the Gallant–Lambert–Vanstone (GLV) method. Iijima, Matsuo, Chao and Tsujii gave such homomorphisms for a large class of elliptic curves by working over ${\mathbb{F}}_{p^{2}}$. We extend their results and demonstrate that they can be applied to the GLV method. In general we expect our method to require about 0.75 the time of previous best methods (except for subfield curves, for which Frobenius expansions can be used). We give detailed implementation results which show that the method runs in between 0.70 and 0.83 the time of the previous best methods for elliptic curve point multiplication on general curves.
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endomorphisms for faster elliptic curve cryptography on a large class of curves
International Cryptology Conference, 2009Co-Authors: Steven D Galbraith, Xibin Lin, Michael ScottAbstract:Efficiently computable homomorphisms allow elliptic curve point multiplication to be accelerated using the Gallant-Lambert- Vanstone (GLV) method. We extend results of Iijima, Matsuo, Chao and Tsujii which give such homomorphisms for a large class of elliptic curves by working over ${\mathbb F}_{p^2}$ and demonstrate that these results can be applied to the GLV method. In general we expect our method to require about 0.75 the time of previous best methods (except for subfield curves, for which Frobenius expansions can be used). We give detailed implementation results which show that the method runs in between 0.70 and 0.84 the time of the previous best methods for elliptic curve point multiplication on general curves.
João Bosco Dias Marques - One of the best experts on this subject based on the ideXlab platform.
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Well test analysis under two-phase flow condition : oil and gas
2017Co-Authors: João Bosco Dias MarquesAbstract:Resumo: Este trabalho disserta sobre a análise de teste transitório de produção e de crescimento de pressão em poço vertical sob condição de escoamento bifásico de óleo e gás. Os resultados obtidos são o fator de película e pontos das curvas das permeabilidades efetivas ao óleo e ao gás em função da saturação de óleo. A permeabilidade efetiva em função da saturação do óleo é obtida da combinação da permeabilidade efetiva em função da pressão de teste de poço com a solução de uma equação diferencial ordinária que relaciona a saturação do óleo com a pressão. Um dos métodos, denominado método p2, é desenvolvido a partir da representação da curva da função de pseudopressão, kro/(µoBo) versus a pressão de teste, por meio de duas linhas retas. O problema físico analisado consiste de um reservatório homogêneo operando a partir da pressão de bolha, água conata imóvel e efeitos de capilaridade e de gravidade desprezíveis. Os dados para validação dos métodos são obtidos com testes de poços realizados em modelos de reservatórios preparados num simulador comercial. O método p2 utiliza basicamente pontos e inclinações de retas de curvas típicas, construídas com dados de teste de poço, para determinar o fator de película e as curvas das permeabilidades efetivas aos fluidos. As curvas obtidas pelo método p2 são comparadas com as obtidas por outro método, chamado de método de determinação in situ.Abstract: This thesis provides an analysis of drawdown and buildup tests from vertical well under solution gas-drive conditions. The results obtained include the skin factor and the points of the effective permeability curves for the oil and gas as a function of oil saturation. The effective permeability as a function of oil saturation is the result of a combination of the effective permeability as a function of wellbore pressure and the solution of an ordinary differential equation which relates oil saturation to the pressure. One of the methods, named square-pressure method, is developed using two straight lines to approximate the curve of the pseudo-pressure function, kro/(µoBo) versus the wellbore pressure. The physical problem consists of a homogeneous reservoir operating from bubble-point pressure with immobile connate water, neglecting the capillarity and gravity effects. The data for the validation of the methods was obtained using well tests reservoirs models built in a commercial simulator. The p2 method basically utilizes the points and the straight lines slope of typical curves built from well test data to determinate the effective permeability curves and the skin factor. Then, the results of these curves are compared to those obtained with another method, named in situ determination method
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Well test analysis under two-phase flow condition : oil and gas
Universidade Estadual de Campinas. Faculdade de Engenharia Mecânica e Instituto de Geociências, 2008Co-Authors: João Bosco Dias MarquesAbstract:Este trabalho disserta sobre a análise de teste transitório de produção e de crescimento de pressão em poço vertical sob condição de escoamento bifásico de óleo e gás. Os resultados obtidos são o fator de película e pontos das curvas das permeabilidades efetivas ao óleo e ao gás em função da saturação de óleo. A permeabilidade efetiva em função da saturação do óleo é obtida da combinação da permeabilidade efetiva em função da pressão de teste de poço com a solução de uma equação diferencial ordinária que relaciona a saturação do óleo com a pressão. Um dos métodos, denominado método p2, é desenvolvido a partir da representação da curva da função de pseudopressão, kro/(µoBo) versus a pressão de teste, por meio de duas linhas retas. O problema físico analisado consiste de um reservatório homogêneo operando a partir da pressão de bolha, água conata imóvel e efeitos de capilaridade e de gravidade desprezíveis. Os dados para validação dos métodos são obtidos com testes de poços realizados em modelos de reservatórios preparados num simulador comercial. O método p2 utiliza basicamente pontos e inclinações de retas de curvas típicas, construídas com dados de teste de poço, para determinar o fator de película e as curvas das permeabilidades efetivas aos fluidos. As curvas obtidas pelo método p2 são comparadas com as obtidas por outro método, chamado de método de determinação in situ.This thesis provides an analysis of drawdown and buildup tests from vertical well under solution gas-drive conditions. The results obtained include the skin factor and the points of the effective permeability curves for the oil and gas as a function of oil saturation. The effective permeability as a function of oil saturation is the result of a combination of the effective permeability as a function of wellbore pressure and the solution of an ordinary differential equation which relates oil saturation to the pressure. One of the methods, named square-pressure method, is developed using two straight lines to approximate the curve of the pseudo-pressure function, kro/(µoBo) versus the wellbore pressure. The physical problem consists of a homogeneous reservoir operating from bubble-point pressure with immobile connate water, neglecting the capillarity and gravity effects. The data for the validation of the methods was obtained using well tests reservoirs models built in a commercial simulator. The p2 method basically utilizes the points and the straight lines slope of typical curves built from well test data to determinate the effective permeability curves and the skin factor. Then, the results of these curves are compared to those obtained with another method, named in situ determination method
Xibin Lin - One of the best experts on this subject based on the ideXlab platform.
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endomorphisms for faster elliptic curve cryptography on a large class of curves
Journal of Cryptology, 2011Co-Authors: Steven D Galbraith, Xibin Lin, Michael ScottAbstract:Efficiently computable homomorphisms allow elliptic curve point multiplication to be accelerated using the Gallant–Lambert–Vanstone (GLV) method. Iijima, Matsuo, Chao and Tsujii gave such homomorphisms for a large class of elliptic curves by working over ${\mathbb{F}}_{p^{2}}$. We extend their results and demonstrate that they can be applied to the GLV method. In general we expect our method to require about 0.75 the time of previous best methods (except for subfield curves, for which Frobenius expansions can be used). We give detailed implementation results which show that the method runs in between 0.70 and 0.83 the time of the previous best methods for elliptic curve point multiplication on general curves.
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endomorphisms for faster elliptic curve cryptography on a large class of curves
International Cryptology Conference, 2009Co-Authors: Steven D Galbraith, Xibin Lin, Michael ScottAbstract:Efficiently computable homomorphisms allow elliptic curve point multiplication to be accelerated using the Gallant-Lambert- Vanstone (GLV) method. We extend results of Iijima, Matsuo, Chao and Tsujii which give such homomorphisms for a large class of elliptic curves by working over ${\mathbb F}_{p^2}$ and demonstrate that these results can be applied to the GLV method. In general we expect our method to require about 0.75 the time of previous best methods (except for subfield curves, for which Frobenius expansions can be used). We give detailed implementation results which show that the method runs in between 0.70 and 0.84 the time of the previous best methods for elliptic curve point multiplication on general curves.
