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841.
We give results on the boundedness and compactness of localization operators with two admissible wavelets on for the Weyl-Heisenberg group.  相似文献   
842.
For a bounded function defined on , let be the set of singular values of the (n + 1) x (n + 1) matrix whose (j, k)-entries are equal to
These matrices can be thought of as variable-coefficient Toeplitz matrices or generalized Toeplitz matrices. Matrices of the above form can be also thought of as the discrete analogue of pseudodifferential operators. Under a certain smoothness assumption on the function , we prove that
where the constant c1 and a part of c2 are shown to have explicit integral representations. The other part of c2 turns out to have a resemblance to the Toeplitz case. This asymptotic formula can be viewed as a generalization of the classical theory on singular values of Toeplitz matrices.  相似文献   
843.
We investigate whether parallel shear flows of an incompressible Newtonian fluid with a viscosity which depends linearly on temperature is possible in situations where the temperature changes along the flow direction. It is shown that parallel flow is possible only in planar or axisymmetric geometries. These two situations are investigated further. For either a plane channel or a circular pipe, we show that the temperature variation in the flow direction must be exponential.Received: December 16, 2003; revised: October 11, 2004  相似文献   
844.
洪小叶 《物理实验》2003,23(4):20-22,25
介绍了采用微机数模转换器接口技术实现对小直流电机转速控制的实验方案,并对实验结果进行了讨论.  相似文献   
845.
In this paper, we study the decay rate of solutions to strongly stable, but not exponentially stable linear evolution equations. It is known that the resolvent operator of such an equation must be unbounded on the imaginary axis. Our main result is an estimate of the decay rate when the unboundedness is of polynomial order. We then apply our main theorem to three strongly stable but not exponentially stable systems to obtain the decay rate, which is not available in the literature.Received: July 21, 2003  相似文献   
846.
847.
Let m?−1 be an integer. We give a correspondence between integer solutions to the parametric family of cubic Thue equations
X3mX2Y−(m+3)XY2Y3=λ  相似文献   
848.
For a given graph G with (0, 1)-adjacency matrix AG, the generalized characteristic polynomial of G is defined to be ?G=?G(λ,t)=det(λI-(AG-tDG)), where I is the identity matrix and DG is the diagonal degree matrix of G. In this paper, we are mainly concerned with the problem of characterizing a given graph G by its generalized characteristic polynomial ?G. We show that graphs with the same generalized characteristic polynomials have the same degree sequence, based on which, a unified approach is proposed to show that some families of graphs are characterized by ?G. We also provide a method for constructing graphs with the same generalized characteristic polynomial, by using GM-switching.  相似文献   
849.
Some functions f:R+R+ induce mean of positive numbers and the matrix monotonicity gives a possibility for means of positive definite matrices. Moreover, such a function f can define a linear mapping on matrices (which is basic in the constructions of monotone metrics). The present subject is to check the complete positivity of in the case of a few concrete functions f. This problem has been motivated by applications in quantum information.  相似文献   
850.
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