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161.
162.
The paper is devoted to peculiarities of the deformation quantization in the algebro-geometric context. A direct application of the formality theorem to an algebraic Poisson manifold gives a canonical sheaf of categories deforming coherent sheaves. The global category is very degenerate in general. Thus, we introduce a new notion of a semiformal deformation, a replacement in algebraic geometry of an actual deformation (versus a formal one). Deformed algebras obtained by semiformal deformations are Noetherian and have polynomial growth. We propose constructions of semiformal quantizations of projective and affine algebraic Poisson manifolds satisfying certain natural geometric conditions. Projective symplectic manifolds (e.g. K3 surfaces and Abelian varieties) do not satisfy our conditions, but projective spaces with quadratic Poisson brackets and Poisson–Lie groups can be semiformally quantized. 相似文献
163.
A high‐order element‐based Galerkin method is developed to solve the non‐divergent barotropic vorticity equation (BVE). The solution process involves solving a conservative transport equation for the vorticity fields and a Poisson equation for the stream function fields. The discontinuous Galerkin method is employed for solving the transport equation and a spectral element method (continuous Galerkin) is used for the Poisson equation. A third‐order strong stability preserving explicit Runge–Kutta scheme is used for time integration. A series of tests have been performed to validate the model, which include the evolution of an idealized tropical cyclone and interaction of dual vortices in close proximity. The numerical convergence study is performed by solving the BVE on the sphere where the analytic solution is known. The test results are consistent with physical observations, and the model exhibits exponential convergence. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
164.
岩土强度与变形关系的理论剖析 总被引:1,自引:0,他引:1
深入浅出地阐述了岩土强度与变形关系,并对一些令人困惑的问题进行了讨论和作出可能的解释。 相似文献
165.
A high-order leap-flog based non-dissipative discontinuous Galerkin timedomain method for solving Maxwell's equations is introduced and analyzed. The proposed method combines a centered approximation for the evaluation of fluxes at the interface between neighboring elements, with a Nth-order leap-frog time scheme. Moreover, the interpolation degree is defined at the element level and the mesh is refined locally in a non-conforming way resulting in arbitrary level hanging nodes. The method is proved to be stable under some CFL-like condition on the time step. The convergence of the semi-discrete approximation to Maxwell's equations is established rigorously and bounds on the global divergence error are provided. Numerical experiments with highorder elements show the potential of the method. 相似文献
166.
Russell Hooper Matthijs Toose Christopher W. Macosko Jeffrey J. Derby 《国际流体数值方法杂志》2001,37(7):837-864
A modified boundary element method (BEM) and the DEVSS‐G finite element method (FEM) are applied to model the deformation of a polymeric drop suspended in another fluid subjected to start‐up uniaxial extensional flow. The effects of viscoelasticity, via the Oldroyd‐B differential model, are considered for the drop phase using both FEM and BEM and for both the drop and matrix phases using FEM. Where possible, results are compared with the linear deformation theory. Consistent predictions are obtained among the BEM, FEM, and linear theory for purely Newtonian systems and between FEM and linear theory for fully viscoelastic systems. FEM and BEM predictions for viscoelastic drops in a Newtonian matrix agree very well at short times but differ at longer times, with worst agreement occurring as critical flow strength is approached. This suggests that the dominant computational advantages held by the BEM over the FEM for this and similar problems may diminish or even disappear when the issue of accuracy is appropriately considered. Fully viscoelastic problems, which are only feasible using the FEM formulation, shed new insight on the role of viscoelasticity of the matrix fluid in drop deformation. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
167.
168.
1999年,Chilcott研究了α-甘氨酸单晶电阻抗随温度的变化,发现晶体在304 K开始导电。为了了解其导电机理,本文研究90 K到340 K的拉曼光谱,发现在α-甘氨酸单晶中NH3+扭曲振动模式分裂,表现为N-H(6)…O(1)(491 cm-1)和N-H(7)…O(2)(483 cm-1)模式,以及CO2-摇摆模式(503cm-1),在304 K均有不连续性变化,并与变温中子衍射晶体结构层内的氢键N-H(6)…O(1)键角和N-H(7)…O(2)长度出现转折点一致。由于α-甘氨酸晶胞中NH3+和CO2-基团构成的电偶极子在变温下重新定向,出现两性离子电荷重心变化致使晶体极化,引起晶体在304 K左右发生了铁电相变。 相似文献
169.
The Coherent Gradient Sensor (CGS) is extended to the optical differentiation of specular, diffracted wave fronts leading
to the combined measurement of in- and out-of-plane displacement field gradients. A derivation of the underlying optical interference
principles is presented along with an analysis of the effective instrument sensitivity. In order to demonstrate the capabilities
of the technique, experimental measurements of crack-tip deformation fields were conducted under various loading conditions
corresponding to mode-I, mode-II, and mixed mode near-tip crack fields. The experimental procedures and results of these tests
are presented as validation of the technique. 相似文献
170.
M. V. Buntina V. V. Ostapenko 《Computational Mathematics and Mathematical Physics》2008,48(12):2241-2253
For the shallow water equations in the first approximation (Saint-Venant equations), a TVD scheme is developed for shock-capturing computations of open channel flows with discontinuous waves. The scheme is based on a special nondivergence approximation of the total momentum equation that does not involve integrals related to the cross-section pressure force and the channel wall reaction. In standard divergence difference schemes, most of the CPU time is spent on the computation of these integrals. Test computations demonstrate that the discontinuity relations reproduced by the scheme are accurate enough for actual discontinuous wave propagation to be numerically simulated. All the qualitatively distinct solutions for a dam collapsing in a trapezoidal channel with a contraction in the tailwater area are constructed as an example. 相似文献