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101.
We prove a uniqueness theorem for two non-constant meromorphic functions sharing three values which improves a recent result of T.C. Alzahary. As a consequence of our main result we also improve a theorem of G. Brosch. 相似文献
102.
Orest Bucicovschi 《Discrete Applied Mathematics》2008,156(18):3518-3521
In this note, we study the degree distance of a graph which is a degree analogue of the Wiener index. Given n and e, we determine the minimum degree distance of a connected graph of order n and size e. 相似文献
103.
A simple characterization of weighted Sobolev spaces with bounded multiplication operator 总被引:1,自引:0,他引:1
In this paper we give a simple characterization of weighted Sobolev spaces (with piecewise monotone weights) such that the multiplication operator is bounded: it is bounded if and only if the support of μ0 is large enough. We also prove some basic properties of the appropriate weighted Sobolev spaces. To have bounded multiplication operator has important consequences in Approximation Theory: it implies the uniform bound of the zeros of the corresponding Sobolev orthogonal polynomials, and this fact allows to obtain the asymptotic behavior of Sobolev orthogonal polynomials. 相似文献
104.
The stability of traveling wave solutions of scalar viscous conservation laws is investigated by decomposing perturbations into three components: two far-field components and one near-field component. The linear operators associated to the far-field components are the constant coefficient operators determined by the asymptotic spatial limits of the original operator. Scaling variables can be applied to study the evolution of these components, allowing for the construction of invariant manifolds and the determination of their temporal decay rate. The large time evolution of the near-field component is shown to be governed by that of the far-field components, thus giving it the same temporal decay rate. We also give a discussion of the relationship between this geometric approach and previous results, which demonstrate that the decay rate of perturbations can be increased by requiring that initial data lie in appropriate algebraically weighted spaces. 相似文献
105.
Alexandre Almeida Humberto Rafeiro 《Journal of Mathematical Analysis and Applications》2008,340(2):1336-1346
We study the inversion problem of the Bessel potential operator within the frameworks of the weighted Lebesgue spaces with variable exponent. The inverse operator is constructed by using approximative inverse operators. This generalizes some classical results to the variable exponent setting. 相似文献
106.
Essaid Zerrad Richard Triplett Anjan Biswas 《International Journal of Theoretical Physics》2009,48(6):1583-1588
A new numerical method of solving integro-differential equations appearing in the theory of atomic and nuclear scattering
systems has been devised. It is termed Singular Value Decomposition Method (SVD). It consists in expanding the exchange kernel
into a number of separable terms by means of the Singular Value Decomposition and then iterating over the remainder. In this
paper, we extend our SVD method to the scattering of low energy electron-helium which has been the subject of interest, both
theoretically and experimentally. We compare our results with the Moments Method which is widely used. The Moments Method
consists of making an expansion of the solution into an especially favorable basis that takes care of the non-exchange part
of the Hamiltonian. 相似文献
107.
该文讨论了$\a$-Bloch空间$\ba$和对数Bloch空间$\bl$之间的加权Ces\'aro算子$\tg$的有界性和紧性,给出$\tg$是$\ba$到$\bl$的有界算子或紧算子的充要条件和$\tg$是$\bl$到$\ba$的有界算子或紧算子的充要条件. 相似文献
108.
Multiple UAVs path planning algorithms: a comparative study 总被引:1,自引:0,他引:1
B. Moses Sathyaraj L. C. Jain A. Finn S. Drake 《Fuzzy Optimization and Decision Making》2008,7(3):257-267
Unmanned aerial vehicles (UAVs) are used in team for detecting targets and keeping them in its sensor range. There are various
algorithms available for searching and monitoring targets. The complexity of the search algorithm increases if the number
of nodes is increased. This paper focuses on multi UAVs path planning and Path Finding algorithms. Number of Path Finding
and Search algorithms was applied to various environments, and their performance compared. The number of searches and also
the computation time increases as the number of nodes increases. The various algorithms studied are Dijkstra’s algorithm,
Bellman Ford’s algorithm, Floyd-Warshall’s algorithm and the AStar algorithm. These search algorithms were compared. The results
show that the AStar algorithm performed better than the other search algorithms. These path finding algorithms were compared
so that a path for communication can be established and monitored. 相似文献
109.
We present here a systematic study of general boundary value problems on weighted networks that includes the variational formulation of such problems. In particular, we obtain the discrete version of the Dirichlet Principle and we apply it to the analysis of the inverse problem of identifying the conductivities of the network in a very general framework. Our approach is based on the development of an efficient vector calculus on weighted networks which mimetizes the calculus in the smooth case. The key tool is an adequate construction of the tangent space at each vertex. This allows us to consider discrete vector fields, inner products and general metrics. Then, we obtain discrete versions of derivative, gradient, divergence and Laplace-Beltrami operators, satisfying analogous properties to those verified by their continuous counterparts. On the other hand we develop the corresponding integral calculus that includes the discrete versions of the Integration by Parts technique and Green’s Identities. Finally, we apply our discrete vector calculus to analyze the consistency of difference schemes used to solve numerically a Robin boundary value problem in a square. 相似文献
110.
Ivan Cheltsov 《Advances in Mathematics》2008,217(1):97-124
We study global log canonical thresholds of anticanonically embedded quasismooth weighted Fano threefold hypersurfaces having terminal quotient singularities to prove the existence of a Kähler-Einstein metric on most of them, and to produce examples of Fano varieties with infinite discrete groups of birational automorphisms. 相似文献