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981.
《Expositiones Mathematicae》2021,39(4):590-603
We generalize Moore’s nonstandard proof of the Spectral theorem for bounded self-adjoint operators to the case of unbounded operators. The key step is to use a definition of the nonstandard hull of an internally bounded self-adjoint operator due to Raab. 相似文献
982.
In this paper, we develop a simplified hybrid weighted essentially non-oscillatory (WENO) method combined with the modified ghost fluid method (MGFM)
[31] to simulate the compressible two-medium flow problems. The MGFM can turn
the two-medium flow problems into two single-medium cases by defining the ghost
fluids state in terms of the predicted the interface state, which makes the material
interface “invisible”. For the single medium flow case, we adapt between the linear
upwind scheme and the WENO scheme automatically by identifying the regions of
the extreme points for the reconstruction polynomial as same as the hybrid WENO
scheme [55]. Instead of calculating their exact locations, we only need to know the
regions of the extreme points based on the zero point existence theorem, which is
simpler for implementation and saves computation time. Meanwhile, it still keeps
the robustness and has high efficiency. Extensive numerical results for both one
and two dimensional two-medium flow problems are performed to demonstrate the
good performances of the proposed method. 相似文献
983.
984.
In this paper, we consider the non-autonomous semilinear impulsive differential equations with state-dependent delay. The approximate controllability results of the first-order systems are obtained in a separable reflexive Banach space, which has a uniformly convex dual. In order to establish sufficient conditions of the approximate controllability of such a system, we have used the theory of linear evolution systems, properties of the resolvent operator and Schauder’s fixed point theorem. Finally, we provide two concrete examples to validate our results. 相似文献
985.
Jiannis K. Pachos 《Contemporary Physics》2013,54(2):375-389
Graphene is a monoatomic layer of graphite with carbon atoms arranged in a two-dimensional honeycomb lattice configuration. It has been known for more than 60 years that the electronic structure of graphene can be modelled by two-dimensional massless relativistic fermions. This property gives rise to numerous applications, both in applied sciences and in theoretical physics. Electronic circuits made out of graphene could take advantage of its high electron mobility that is witnessed even at room temperature. In the theoretical domain the Dirac-like behaviour of graphene can simulate high energy effects, such as the relativistic Klein paradox. Even more surprisingly, topological effects can be encoded in graphene such as the generation of vortices, charge fractionalisation and the emergence of anyons. The impact of the topological effects on graphene's electronic properties can be elegantly described by the Atiyah–Singer index theorem. Here we present a pedagogical encounter of this theorem and review its various applications to graphene. A direct consequence of the index theorem is charge fractionalisation that is usually known from the fractional quantum Hall effect. The charge fractionalisation gives rise to the exciting possibility of realising graphene based anyons that unlike bosons or fermions exhibit fractional statistics. Besides being of theoretical interest, anyons are a strong candidate for performing error free quantum information processing. 相似文献
986.
By using fixed point theorem, we study the following equation g(u′′(t))+a(t)f(u)=0 subject to boundary conditions, where g(v)=|v|p−2v with p>1; the existence of at least three positive solutions is proved. 相似文献
987.
本文运用Zorn引理,得出了正则锥上的非紧非单调算子的不动点的存在性的结果,并用于讨论Strum-Liouville奇异边值问题,得出了有关解的存在性的全新的结论. 相似文献
988.
Peter Apostoli 《Mathematical Logic Quarterly》1996,42(1):175-190
This paper articulates the structure of a two species of weakly aggregative necessity in a common idiom, neighbourhood semantics, using the notion of a k-filter of propositions. A k-filter on a non-empty set I is a collection of subsets of I which (i) contains I, (ii) is closed under supersets on I, and (iii) contains ∪{Xi ≤ Xj : 0 ≤ i < j ≤ k} whenever it contains the subsets X0,…, Xk. The mathematical content of the proof that weakly aggregative modal logic is complete relative to k-ary frame theory, the standard semantic idiom for weakly aggregative modal logic (see [1]) is presented in language-independent terms as a representation theorem for k-filters: every non-trivial k-filter is included in the union of ≤ k non-trivial filters. The elementary theory of k-filters is developed and then applied in the form of an ultrafilter extension result for k-ary frame theory. Mathematics Subject Classification: 03B45. 相似文献
989.
We derive a set of sufficient conditions for the existence of solutions of a Hammerstein integral equation. 相似文献
990.
We apply large-deviation theory to particle systems with a random mean-field interaction in the McKean-Vlasov limit. In particular, we describe large deviations and normal fluctuations around the McKean-Vlasov equation. Due to the randomness in the interaction, the McKean-Vlasov equation is a collection of coupled PDEs indexed by the state space of the single components in the medium. As a result, the study of its solution and of the finite-size fluctuation around this solution requires some new ingredient as compared to existing techniques for nonrandom interaction. 相似文献