Waves occurring in a compressible inviscid fluid rotating as a solid body within a circular cylinder are reexamined for the particular case where the disturbance frequency in the rotating system is equal to twice that...
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作者：
Zhiming ChenGuanghui HuangLSEC
Institute of Computational MathematicsAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences
University of Chinese Academy of SciencesBeijing 100049China The Rice Inversion Project
Department of Computational and Applied MathematicsRice UniversityHoustonTX 77005-1892USA
We propose a reliable direct imaging method based on the reverse time migration for finding extended obstacles with phaseless total field *** prove that the imaging resolution of the method is essentially the same as ...
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We propose a reliable direct imaging method based on the reverse time migration for finding extended obstacles with phaseless total field *** prove that the imaging resolution of the method is essentially the same as the imaging results using the scattering data with full phase information when the measurement is far away from the *** imaginary part of the cross-correlation imaging functional always peaks on the boundary of the *** experiments are included to illustrate the powerful imaging quality.
We target here to solve numerically a class of nonlinear fractional two-point boundary value problems involving left-and right-sided fractional *** main ingredient of the proposed method is to recast the problem into ...
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We target here to solve numerically a class of nonlinear fractional two-point boundary value problems involving left-and right-sided fractional *** main ingredient of the proposed method is to recast the problem into an equivalent system of weakly singular integral ***,a Legendre-based spectral collocation method is developed for solving the transformed ***,we can make good use of the advantages of the Gauss quadrature *** present the construction and analysis of the collocation *** results can be indirectly applied to solve fractional optimal control problems by considering the corresponding Euler–Lagrange *** numerical examples are given to confirm the convergence analysis and robustness of the scheme.
We present total cross sections in the laboratory energy range 17.5-500 keV amu(-1) for electron capture by protons in collision with He+(1s). We describe this process theoretically by performing a close-coupling (CC)...
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We present total cross sections in the laboratory energy range 17.5-500 keV amu(-1) for electron capture by protons in collision with He+(1s). We describe this process theoretically by performing a close-coupling (CC) calculation using the symmetrized variational (SV) continuum distorted-wave (CDW) collision ansatz. We discuss the SVCDW results in conjunction with another CC variational CDW calculation, with CDW perturbation theory, and also with close-coupling calculations which involve a representation of the continuum by a set of pseudo-states which may include pseudo-states of the united atom. Moreover, we compare the SVCDW results with the available experimental data. The SVCDW results are found to be in very good agreement with the experiments of Peart et al, Rinn et al and Watts et al at all energies, and consequently to be at variance with the experimental results of Angel et al. The SVCDW results are also found to be in good accord with a CC calculation involving Sturmian-type pseudo-states. We investigate this agreement further by comparing impact-parameter profiles at 50 and 17.5 keV amu(-1).
The behavior of interacting electrons in a perfect crystal under macroscopic external electric and magnetic fields is studied. Effective Maxwell equations for the macroscopic electric and magnetic fields are derived s...
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The behavior of interacting electrons in a perfect crystal under macroscopic external electric and magnetic fields is studied. Effective Maxwell equations for the macroscopic electric and magnetic fields are derived starting from time-dependent density functional theory. Effective permittivity and permeability coefficients are obtained.
We present some explicit self-similar blow-up solutions and some other solutions of the incompressible threedimensional Navier Stokes equations. These solutions indicate that in C^∞ the solution of Navier-Stokes equa...
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We present some explicit self-similar blow-up solutions and some other solutions of the incompressible threedimensional Navier Stokes equations. These solutions indicate that in C^∞ the solution of Navier-Stokes equations does not always tend to a solution of Euler equations.
Fourth-order stream-function methods are proposed for the time dependent, incom- pressible Navier-Stokes and Boussinesq equations. Wide difference stencils are used instead of compact ones and the boundary terms are h...
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Fourth-order stream-function methods are proposed for the time dependent, incom- pressible Navier-Stokes and Boussinesq equations. Wide difference stencils are used instead of compact ones and the boundary terms are handled by extrapolating the stream-function values inside the computational domain to grid points outside, up to fourth-order in the noslip condition. Formal error analysis is done for a simple model problem, showing that this extrapolation introduces numerical boundary layers at fifth-order in the stream-function. The fourth-order convergence in velocity of the proposed method for the full problem is shown numerically.
We derive tight expressions for the maximum number of κ-faces, 0 ≤ κ ≤ d - 1, of the Minkowski sum, P1++Pr, of r convex d-polytopes P1, . . . ,Pr in d, where d ≥ 2 and r 1 + + Pr as a section of the Cayley polyto...
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ISBN:
(纸本)9783939897835
We derive tight expressions for the maximum number of κ-faces, 0 ≤ κ ≤ d - 1, of the Minkowski sum, P1++Pr, of r convex d-polytopes P1, . . . ,Pr in d, where d ≥ 2 and r 1 + + Pr as a section of the Cayley polytope C of the summands;bounding the κ-faces of P1 + + Pr reduces to bounding the subset of the (k + r - 1)-faces of C that contain vertices from each of the r polytopes. We end our paper with a sketch of an explicit construction that establishes the tightness of the upper bounds.
In structural health monitoring, detection of localized damage can be achieved by exploiting recorded signals at a limited number of sensors within the structure. Here we propose the localization of damage using an ar...
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In structural health monitoring, detection of localized damage can be achieved by exploiting recorded signals at a limited number of sensors within the structure. Here we propose the localization of damage using an array of sensors as a computational time-reversal mirror (TRM). Time reversal (TR) is a physical process that exploits the time reversibility of wave equations and achieves re-focusing of the wave on the source of its origin by sending back, reversed in time, the signals recorded on an array of transducers. TR was originally introduced by Mathias Fink and his group and has several applications ranging from medical imaging to telecommunications [14]. In the present work, we perform time reversal numerically in order to effectively detect and localize defects in a bounded two-dimensional elastic domain. This is a generalization of a respective time-reversal implementation in an acoustic medium [12]. The solid contains a number of Nr sensors which can act as sources as well. Our data is the response matrix of the scattered field, that is, the difference between the total field obtained in the damaged structure and the incident field corresponding to the response in the healthy structure. Numerical solution of the wave propagation problem is performed using a mixed finite element formulation in terms of the velocity and stress fields [6]. In order to dissociate the response caused by Nd different defects, we apply the singular value decomposition (SVD) of the response matrix, while back-propagation of the projection of each singular vector corresponding to a non-zero singular value is performed in order to highlight each defect separately.
We discuss the development,verification,and performance of a GPU accelerated discontinuous Galerkin method for the solutions of two dimensional nonlinear shallow water *** shallow water equations are hyperbolic partia...
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We discuss the development,verification,and performance of a GPU accelerated discontinuous Galerkin method for the solutions of two dimensional nonlinear shallow water *** shallow water equations are hyperbolic partial differential equations and are widely used in the simulation of tsunami wave *** algorithms are tailored to take advantage of the single instruction multiple data(SIMD)architecture of graphic processing *** time integration is accelerated by local time stepping based on a multi-rate Adams-Bashforth scheme.A total variational bounded limiter is adopted for nonlinear stability of the numerical *** limiter is coupled with a mass and momentum conserving positivity preserving limiter for the special treatment of a dry or partially wet element in the ***,robustness and performance are demonstrated with the aid of test ***,we developed a unified multi-threading model *** kernels expressed in OCCA model can be cross-compiled with multi-threading models OpenCL,CUDA,and *** compare the performance of the OCCA kernels when cross-compiled with these models.
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