共查询到20条相似文献,搜索用时 125 毫秒
1.
We consider the problem of deciding whether a given rational function has a power series expansion with all its coefficients positive. Introducing an elementary transformation that preserves such positivity we are able to provide an elementary proof for the positivity of Szegö's function which has been at the historical root of this subject starting with Szegö. We then demonstrate how to apply the transformation to prove a 4-dimensional generalization of the above function, and close with discussing the set of parameters (a,b) such that has positive coefficients. 相似文献
2.
In this work the existence of a global solution for the mixed problem associated to the nonlinear equationis proved in a Hilbert space framework by using Galerkin method. 相似文献
3.
Let X be a metric space andμa finite Borel measure on X. Let pμq,t and pμq,t be the packing premeasure and the packing measure on X, respectively, defined by the gauge (μB(x,r))q(2r)t, where q, t∈R. For any compact set E of finite packing premeasure the authors prove: (1) if q≤0 then pμq,t(E)=pμq,t(E);(2)if q>0 andμis doubling on E then pμq,t(E) and pμq,t(E) are both zero or neither. 相似文献
4.
王阳 《数学物理学报(B辑英文版)》2007,27(2):274-282
This article consider, for the following heat equation ut/|x|s-△pu=uq,(x,t)∈Ω×(0,T), u(x,t)=0,(x,t)∈(?)Ω×(0,T), u(x,0)=u0(x),u0(x)≥0,u0(x)(?)0 the existence of global solution under some conditions and give two sufficient conditions for the blow up of local solution in finite time, whereΩis a smooth bounded domain in RN(N>p),0∈Ω,△pu=div(|▽u|p-2▽u),0≤s≤2,p≥2,p-1
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5.
In this paper, the existence of a positive solution of the boundary value problem of the following fourth-order nonlinear differential equation: is discussed. 相似文献
6.
Global stability of a difference equation with maximum 总被引:1,自引:1,他引:0
Stevo Stevi 《Applied mathematics and computation》2009,210(2):525-529
We prove that every positive solution to the difference equationwhere , i=1,…,k, converges to the following quantity , confirming a quite recent conjecture of interest. We also prove another result on global convergence which concerns some cases when not all αi,i=1,…,k belong to the interval (0, 1). 相似文献
7.
By using the integral operator, we establish some oscillation criteria for the damped half-linear PDE The results are extensions of integral averaging technique of Kamenev and include earlier results of Usami, Xu and Xing. 相似文献
8.
Let be a bounded domain such that 0Ω. Denote by , the set of all complex polynomials of degree at most n. Let where . We relate the maximal polynomial range to the geometry of Ω. 相似文献
9.
Blow-up analysis for a system of heat equations with nonlinear flux which obey different laws 总被引:1,自引:0,他引:1
We consider a system of heat equations ut=Δu and vt=Δv in Ω×(0,T) completely coupled by nonlinear boundary conditions We prove that the solutions always blow up in finite time for non-zero and non-negative initial values. Also, the blow-up only occurs on ∂Ω with for p,q>0, 0≤α<1 and 0≤β<p. 相似文献
10.
Ivan Kiguradze Tariel Kiguradze 《Nonlinear Analysis: Theory, Methods & Applications》2008,69(7):1914-1933
In the rectangle Ω=[0,a]×[0,b] for the nonlinear hyperbolic equation the boundary value problems of the type are considered, where and are linear bounded functionals.Sufficient conditions of solvability and unique solvability of the general problem and its particular cases (Nicoletti type, Dirichlet, Lidstone and Periodic problems) are established. 相似文献
11.
In this paper we stochastically perturb the functional Kolmogorov-type system into the stochastic functional differential equation This paper studies existence and uniqueness of the global positive solution, and its asymptotic bound properties and moment average in time. These properties are natural requirements from the biological point of view. As the special cases, we discuss the various stochastic Lotka–Volterra systems. 相似文献
12.
Existence and multiplicity of positive solutions of a nonlinear eigenvalue problem with indefinite weight function 总被引:1,自引:0,他引:1
This paper is concerned with the existence, multiplicity and stability of positive solutions of an indefinite weight boundary value problemwhere aC[0,1] changes sign. The proof of our main result is based upon bifurcation techniques. 相似文献
13.
The purpose of this paper is to establish the exponential decay properties of the solutions for the nonlinear multiharmonic equation where the condition plays the role of a boundary value condition. 相似文献
14.
A. Lomtatidze S. Mukhigulashvili J. remr 《Mathematical and Computer Modelling》2008,47(11-12):1292-1313
On the rectangle , the problem on the existence and uniqueness of a nonnegative solution of the characteristic initial value problem for the equation is considered, where is a linear bounded operator and . 相似文献
15.
Let be a bounded Lipschitz domain, a suitably quasiconvex integrand and consider the energy functional over the space of measure preserving maps In this paper we discuss the question of existence of multiple strong local minimizers for over . Moreover, motivated by their significance in topology and the study of mapping class groups, we consider a class of maps, referred to as twists, and examine them in connection with the corresponding Euler–Lagrange equations and investigate various qualitative properties of the resulting solutions, the stationary twists. Particular attention is paid to the special case of the so-called p-Dirichlet energy, i.e., when . 相似文献
16.
In this paper, we consider a Dirichlet problem involving the p(x)-Laplacian of the type We prove the existence of infinitely many non-negative solutions of the problem by applying a general variational principle due to B. Ricceri and the theory of the variable exponent Sobolev spaces. 相似文献
17.
This paper gives upper and lower bounds of the Christoffel-type functions , for the m-orthogonal polynomials for a Freud weight W=e-Q, which are given as follows. Let an=an(Q) be the nth Mhaskar–Rahmanov–Saff number, φn(x)=max{n-2/3,1-|x|/an}, and d>0. Assume that QC(R) is even, , and for some A,B>1Then for xRand for |x|an(1+dn-2/3) 相似文献
18.
We consider the eigenvalue problems for boundary value problems of second order difference equations(1) and(2) Comparison results for the eigenvalues of the problem (1) and the problem (2) are established. 相似文献
19.
Denis Bonheure Patrick Habets Franco Obersnel Pierpaolo Omari 《Journal of Differential Equations》2007,243(2):208-237
We discuss existence and multiplicity of positive solutions of the one-dimensional prescribed curvature problem depending on the behaviour at the origin and at infinity of the potential . Besides solutions in W2,1(0,1), we also consider solutions in which are possibly discontinuous at the endpoints of [0,1]. Our approach is essentially variational and is based on a regularization of the action functional associated with the curvature problem. 相似文献
20.
Let , and for k=0,1,…, denote the orthonormalized Jacobi polynomial of degree k. We discuss the construction of a matrix H so that there exist positive constants c, c1, depending only on H, α, and β such that Specializing to the case of Chebyshev polynomials, , we apply this theory to obtain a construction of an exponentially localized polynomial basis for the corresponding L2 space. 相似文献