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神奇的生物三节律
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作者 龙惊云 《科学之友》 2002年第10期42-42,共1页
上世纪初,英国医生费里斯和德国心理学家斯沃博特同时发现了一个奇怪的现象:有一些病人如头痛、精神疲倦等,每隔23天或28天就来治疗一次.于是他们就将23天称为"体力定律",28天称为"情绪定律".而在20年后,特里舍尔... 上世纪初,英国医生费里斯和德国心理学家斯沃博特同时发现了一个奇怪的现象:有一些病人如头痛、精神疲倦等,每隔23天或28天就来治疗一次.于是他们就将23天称为"体力定律",28天称为"情绪定律".而在20年后,特里舍尔发现学生的智力是以33天为周期进行变化的,于是他就将其称为"智力定律".后来,人们就将"体力定律"、"智力定律"和"情绪定律"总称为生物三节律. 展开更多
关键词 体力定律 智力定律 情绪定律 生物节律
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Integrable Hierarchy Covering the Lattice Burgers Equation in Fluid Mechanics:N-fold Darboux Transformation and Conservation Laws 被引量:1
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作者 闻小永 高以天 +3 位作者 薛玉山 郭睿 齐凤华 于鑫 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第9期323-330,共8页
Burgers-type equations can describe some phenomena in fluids,plasmas,gas dynamics,traffic,etc.In this paper,an integrable hierarchy covering the lattice Burgers equation is derived from a discrete spectral problem.N-f... Burgers-type equations can describe some phenomena in fluids,plasmas,gas dynamics,traffic,etc.In this paper,an integrable hierarchy covering the lattice Burgers equation is derived from a discrete spectral problem.N-fold Darboux transformation(DT) and conservation laws for the lattice Burgers equation are constructed based on its Lax pair.N-soliton solutions in the form of Vandermonde-like determinant are derived via the resulting DT with symbolic computation,structures of which are shown graphically.Coexistence of the elastic-inelastic interaction among the three solitons is firstly reported for the lattice Burgers equation,even if the similar phenomenon for certern continuous systems is known.Results in this paper might be helpful for understanding some ecological problems describing the evolution of competing species and the propagation of nonlinear waves in fluids. 展开更多
关键词 discrete spectral problem lattice Burgers equation N-fold Darboux transformation conservationlaws symbolic computation
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An Energy Stable Monolithic Eulerian Fluid-Structure Numerical Scheme
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作者 olivier pironneau 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2018年第2期213-232,共20页
The conservation laws of continuum mechanics, written in an Eulerian frame,do not distinguish fluids and solids, except in the expression of the stress tensors, usually with Newton's hypothesis for the fluids and ... The conservation laws of continuum mechanics, written in an Eulerian frame,do not distinguish fluids and solids, except in the expression of the stress tensors, usually with Newton's hypothesis for the fluids and Helmholtz potentials of energy for hyperelastic solids. By taking the velocities as unknown monolithic methods for fluid structure interactions(FSI for short) are built. In this paper such a formulation is analysed when the solid is compressible and the fluid is incompressible. The idea is not new but the progress of mesh generators and numerical schemes like the Characteristics-Galerkin method render this approach feasible and reasonably robust. In this paper the method and its discretisation are presented, stability is discussed through an energy estimate. A numerical section discusses implementation issues and presents a few simple tests. 展开更多
关键词 Fluid-Structure interactions Numerical method Energy stability Finiteelement method
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