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31.
Peter G. Ovchinnikov 《Proceedings of the American Mathematical Society》1997,125(10):2839-2841
An arbitrary orthoposet is shown to be isomorphic to , being a subbasis of a Hausdorff topological space satisfying 1) , 2) , and 3) every covering of by elements of possesses an at most 2-element subcovering. The couple turns out to be unique.
32.
33.
高密度光数据存储技术的发展 总被引:11,自引:1,他引:11
讨论了信息技术发展中信息数据存储的重要性,比较了磁存储和光存储的各自特点,介绍了光盘存储技术的发展趋势和高度光盘存储技术的关键问题,进一步讨论了超高密度光存储的发展可能。 相似文献
34.
35.
In this paper, we consider a non-local PDE model with delay for population dynamics in ℝ
n
. First, we prove the existence and uniqueness of weak solutions under some suitable decayed assumptions on non-local term
at infinity. Then, we obtain the global attractor by proving ω-limit compactness property of the solution operator semigroup. 相似文献
36.
文中给出了对一个新型紧凑的电子直线加速器(linac)证明原理的研究结果.在该linac中,通过偏转磁场选择特定能量和相位的大功率速调管用毕束流,然后将它们注入到加速节中,同时使速调管工作在自激振荡状态,使传统linac上的许多部件都可以省去.据此建成的linac的结构简单、维护容易、性能良好、造价经济.因此实现这种具有众多优点的新型linac将有助于linac应用的推广.要实现这样的linac有许多关键的问题需要解决.电子束团的性能参量,如能量、电流、发射度,以及速调管自激振荡的频率稳定度等都必须符合加速的要求.文中给出的计算机模拟和实验结果都表明了实现这种新型的linac的可行性 相似文献
37.
Jung-Chan Chang 《Mathematical Methods in the Applied Sciences》2020,43(6):3586-3601
In this paper, by using some well-known inequalities and Schaefer fixed point theorem, we show existence results for impulsive Cauchy problems with nonlocal conditions. The compactness of solution sets can be shown in some certain conditions. Moreover, connectedness of solution sets to impulsive Cauchy problems is shown. 相似文献
38.
Manuel Bernard Ghislain Lartigue Guillaume Balarac Vincent Moureau Guillaume Puigt 《国际流体数值方法杂志》2020,92(11):1551-1583
In this article, a new framework to design high-order approximations in the context of node-centered finite volumes on simplicial meshes is proposed. The major novelty of this method is that it relies on very simple and compact differential operators, which is a critical point to achieve good performances in the High-performance computing context. This method is based on deconvolution between nodal and volume-average values, which can be conducted to any order. The interest of the new method is illustrated through three different applications: mesh-to-mesh interpolation, levelset curvature computation, and numerical scheme for convection. Higher order can also be achieved within the present framework by introducing high-rank tensors. Although these tensors feature much symmetries, their manipulation can quickly become an overwhelming task. For this reason and without loss of generality, the present articles are limited to third-order expansion. This method, although tightly connected to the k-exact schemes theory, does not rely on successive corrections: the high-order property is obtained in a single operation, which makes them more attractive in terms of performances. 相似文献
39.
We put forth a dynamic computing framework for scale‐selective adaptation of weighted essential nonoscillatory (WENO) schemes for the simulation of hyperbolic conservation laws exhibiting strong discontinuities. A multilevel wavelet‐based multiresolution procedure, embedded in a conservative finite volume formulation, is used for a twofold purpose. (i) a dynamic grid adaptation of the solution field for redistributing grid points optimally (in some sense) according to the underlying flow structures, and (ii) a dynamic minimization of the in built artificial dissipation of WENO schemes. Taking advantage of the structure detection properties of this multiresolution algorithm, the nonlinear weights of the conventional WENO implementation are selectively modified to ensure lower dissipation in smoother areas. This modification is implemented through a linear transition from the fifth‐order upwind stencil at the coarsest regions of the adaptive grid to a fully nonlinear fifth‐order WENO scheme at areas of high irregularity. Therefore, our computing algorithm consists of a dynamic grid adaptation strategy, a scale‐selective state reconstruction, a conservative flux calculation, and a total variation diminishing Runge‐Kutta scheme for time advancement. Results are presented for canonical examples drawn from the inviscid Burgers, shallow water, Euler, and magnetohydrodynamic equations. Our findings represent a novel direction for providing a scale‐selective dissipation process without a compromise on shock capturing behavior for conservation laws, which would be a strong contender for dynamic implicit large eddy simulation approaches. 相似文献
40.
本文研究了度量空间的象,引进诱导紧覆盖弱紧映射,建立了具有σ点有限cfp网的空间与度量空间之间的联系,将完善"映射与空间"理论. 相似文献