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SPH方法中常数一致性核函数的建立及公式化 被引量:3
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作者 徐绯 郑茂军 菊池正纪 《计算力学学报》 EI CAS CSCD 北大核心 2008年第1期48-53,共6页
施加边界条件的不足是SPH方法的一个棘手问题,因为在结构边界外没有颗粒的存在,使得在边界处核函数的单位特性不能得到满足。施加"伪"颗粒是目前通用的一种方法,但是对于不规则结构和复杂几何边界,确定这些"伪"颗... 施加边界条件的不足是SPH方法的一个棘手问题,因为在结构边界外没有颗粒的存在,使得在边界处核函数的单位特性不能得到满足。施加"伪"颗粒是目前通用的一种方法,但是对于不规则结构和复杂几何边界,确定这些"伪"颗粒非常困难。本文讨论通过使用满足常数一致性的核函数来改善边界的不足。文章首先通过三种方法推导了满足常数一致性条件的核函数及其函数梯度的表达式,发现了两个不同分母式的表达,分析了满足常数一致性的修正核函数的数学特性。开展了二维和三维的算例比较,结果发现使用修正的核函数对边界条件有明显改善,对计算精度和稳定性也有显著提高。 展开更多
关键词 光滑粒子流体动力学方法(SPH) 核函数 常数一致性 常数完备性 公式化
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Finite-time adaptive consensus of a class of multi-agent systems 被引量:17
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作者 LIU KeXin WU LuLu +1 位作者 Lü JinHu ZHU HengHui 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第1期22-32,共11页
Multi-agent systems(MASs) are ubiquitous in natural and artificial systems. This paper aims to establish the finite-time adaptive consensus criterion for a class of MASs with nonlinear dynamics. Traditionally, the fin... Multi-agent systems(MASs) are ubiquitous in natural and artificial systems. This paper aims to establish the finite-time adaptive consensus criterion for a class of MASs with nonlinear dynamics. Traditionally, the finite-time consensus criterion is often established based on the prior information on Lipschitz constants and the eigenvalues of Laplacian matrix. However, it is difficult to acquire the above prior information for most real-world engineering systems. To overcome the above difficulty, this paper develops the finite-time consensus criteria for a class of MASs with nonlinear dynamics via adaptive technique. In detail, we design the finite-time distributed node-based and edge-based adaptive consensus protocols for a class of MASs with fixed and switching topologies. Numerical simulations are also given to validate the proposed finite-time adaptive consensus criterion. 展开更多
关键词 Multi-agent systems adaptive control finite-time consensus switching topology
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A Study of Gaugeon Formalism for QED in Lorentz Violating Background
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作者 Mushtaq B.Shah Prince A.Ganai 《Communications in Theoretical Physics》 SCIE CAS CSCD 2018年第2期166-172,共7页
At the energy regimes close to Planck scales, the usual structure of Lorentz symmetry fails to address certain fundamental issues and eventually breaks down, thus paving the way for an alternative road map. It is thus... At the energy regimes close to Planck scales, the usual structure of Lorentz symmetry fails to address certain fundamental issues and eventually breaks down, thus paving the way for an alternative road map. It is thus argued that some subgroup of proper Lorentz group could stand consistent and might possibly help us to circumvent this problem.It is this subgroup that goes by the name of Very Special Relativity(VSR). Apart from violating rotational symmetry,VSR is believed to preserve the very tenets of special relativity. The gaugeon formalism due to type-I Yokoyama and type-II Izawa are found to be invariant under BRST symmetry. In this paper, we analyze the scope of this invariance in the scheme of VSR. Furthermore, we will obtain VSR modified Lagrangian density using path integral derivation. We will explore the consistency of VSR with regard to these theories. 展开更多
关键词 quantum electrodynamics very special relativity BRST symmetry gaugeon formalism
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