共查询到20条相似文献,搜索用时 748 毫秒
1.
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
2.
In this paper, we afford some sufficient conditions to guarantee the existence of multiple positive solutions for the nonlinear m-point boundary-value problem for the one-dimensional p-Laplacian 相似文献
(φp(u′))′+f(t,u)=0, t(0,1),
3.
Thomas Kühn Hans-Gerd Leopold Winfried Sickel Leszek Skrzypczak 《Journal of Approximation Theory》2003,121(2):244-268
Let
be the radial subspace of the Besov space
. We prove the independence of the asymptotic behavior of the entropy numbersfrom the difference s0−s1 as long as the embedding itself
is compact. In fact, we shall show thatThis is in a certain contrast to earlier results on entropy numbers in the context of Besov spaces Bp,qs(Ω) on bounded domains Ω. 相似文献
4.
Dehong Ji Yu Tian Weigao Ge 《Nonlinear Analysis: Theory, Methods & Applications》2009,71(11):5406-5416
This paper deals with the existence of positive solutions for the one-dimensional p-Laplacian subject to the boundary value conditions: where p(s)=|s|p−2s,p>1. We show that it has at least one or two positive solutions under some assumptions by applying the fixed point theorem. The interesting points are that the nonlinear term f is involved with the first-order derivative explicitly and f may change sign. 相似文献
5.
We consider a Cauchy problem for a semilinear heat equation with p>pS where pS is the Sobolev exponent. If u(x,t)=(T−t)−1/(p−1)φ((T−t)−1/2x) for xRN and t[0,T), where φ is a regular positive solution of(P) then u is called a backward self-similar blowup solution. It is immediate that (P) has a trivial positive solution κ≡(p−1)−1/(p−1) for all p>1. Let pL be the Lepin exponent. Lepin obtained a radial regular positive solution of (P) except κ for pS<p<pL. We show that there exist no radial regular positive solutions of (P) which are spatially inhomogeneous for p>pL. 相似文献
6.
F. Andreu J.M. Mazn J.D. Rossi J. Toledo 《Journal de Mathématiques Pures et Appliquées》2008,90(2):201-227
In this paper we study the nonlocal p-Laplacian type diffusion equation, If p>1, this is the nonlocal analogous problem to the well-known local p-Laplacian evolution equation ut=div(|u|p−2u) with homogeneous Neumann boundary conditions. We prove existence and uniqueness of a strong solution, and if the kernel J is rescaled in an appropriate way, we show that the solutions to the corresponding nonlocal problems converge strongly in L∞(0,T;Lp(Ω)) to the solution of the p-Laplacian with homogeneous Neumann boundary conditions. The extreme case p=1, that is, the nonlocal analogous to the total variation flow, is also analyzed. Finally, we study the asymptotic behavior of the solutions as t goes to infinity, showing the convergence to the mean value of the initial condition. 相似文献
7.
Gradimir V. Milovanovi Miodrag M. Spalevi 《Journal of Computational and Applied Mathematics》2002,140(1-2)
Let dλ(t) be a given nonnegative measure on the real line
, with compact or infinite support, for which all moments
exist and are finite, and μ0>0. Quadrature formulas of Chakalov–Popoviciu type with multiple nodeswhere σ=σn=(s1,s2,…,sn) is a given sequence of nonnegative integers, are considered. A such quadrature formula has maximum degree of exactness dmax=2∑ν=1nsν+2n−1 if and only ifThe proof of the uniqueness of the extremal nodes τ1,τ2,…,τn was given first by Ghizzetti and Ossicini (Rend. Mat. 6(8) (1975) 1–15). Here, an alternative simple proof of the existence and the uniqueness of such quadrature formulas is presented. In a study of the error term R(f), an influence function is introduced, its relevant properties are investigated, and in certain classes of functions the error estimate is given. A numerically stable iterative procedure, with quadratic convergence, for determining the nodes τν, ν=1,2,…,n, which are the zeros of the corresponding σ-orthogonal polynomial, is presented. Finally, in order to show a numerical efficiency of the proposed procedure, a few numerical examples are included. 相似文献
8.
We study the large time asymptotic behavior, in Lp (1p∞), of higher derivatives Dγu(t) of solutions of the nonlinear equation(1) where the integers n and θ are bigger than or equal to 1, a is a constant vector in with . The function ψ is a nonlinearity such that and ψ(0)=0, and is a higher order elliptic operator with nonsmooth bounded measurable coefficients on . We also establish faster decay when . 相似文献
9.
Vladimir Koltchinskii 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2003,39(6):1143-978
Let
be a probability space and let Pn be the empirical measure based on i.i.d. sample (X1,…,Xn) from P. Let
be a class of measurable real valued functions on
For
define Ff(t):=P{ft} and Fn,f(t):=Pn{ft}. Given γ(0,1], define n,γ(δ):=1/(n1−γ/2δγ). We show that if the L2(Pn)-entropy of the class
grows as −α for some α(0,2), then, for all
and all δ(0,Δn), Δn=O(n1/2), and where
and c(σ)↓1 as σ↓0 (the above inequalities hold for any fixed σ(0,1] with a high probability). Also, define Then for all
uniformly in
and with probability 1 (for
the above ratio is bounded away from 0 and from ∞). The results are motivated by recent developments in machine learning, where they are used to bound the generalization error of learning algorithms. We also prove some more general results of similar nature, show the sharpness of the conditions and discuss the applications in learning theory. 相似文献
10.
Jorge García-Melin 《Journal of Mathematical Analysis and Applications》2009,360(2):530-536
In this paper we prove the uniqueness of the positive solution for the boundary blow-up problem where Ω is a C2 bounded domain in , under the hypotheses that f(t) is nondecreasing in t>0 and f(t)/tp is increasing for large t and some p>1. We also consider the uniqueness of a related problem when the equation includes a nonnegative weight a(x). 相似文献
11.
Persistence, contractivity and global stability in logistic equations with piecewise constant delays
Yoshiaki Muroya 《Journal of Mathematical Analysis and Applications》2002,270(2):1532-635
We establish sufficient conditions for the persistence and the contractivity of solutions and the global asymptotic stability for the positive equilibrium N*=1/(a+∑i=0mbi) of the following differential equation with piecewise constant arguments: where r(t) is a nonnegative continuous function on [0,+∞), r(t)0, ∑i=0mbi>0, bi0, i=0,1,2,…,m, and a+∑i=0mbi>0. These new conditions depend on a,b0 and ∑i=1mbi, and hence these are other type conditions than those given by So and Yu (Hokkaido Math. J. 24 (1995) 269–286) and others. In particular, in the case m=0 and r(t)≡r>0, we offer necessary and sufficient conditions for the persistence and contractivity of solutions. We also investigate the following differential equation with nonlinear delay terms: where r(t) is a nonnegative continuous function on [0,+∞), r(t)0, 1−ax−g(x,x,…,x)=0 has a unique solution x*>0 and g(x0,x1,…,xm)C1[(0,+∞)×(0,+∞)××(0,+∞)]. 相似文献
12.
Jesús García-Falset 《Journal of Mathematical Analysis and Applications》2005,310(2):594-608
The purpose of this paper is to study the asymptotic behavior of the solutions of certain type of differential inclusions posed in Banach spaces. In particular, we obtain the abstract result on the asymptotic behavior of the solution of the boundary value problem where Ω is a bounded open domain in with smooth boundary ∂Ω, f(t,x) is a given L1-function on ]0,∞[×Ω, γ1 and 1p<∞. Δp represents the p-Laplacian operator, is the associated Neumann boundary operator and β a maximal monotone graph in with 0β(0). 相似文献
13.
Fbio M. Amorin Natali Ademir Pastor Ferreira 《Journal of Mathematical Analysis and Applications》2008,347(2):428-441
In the present paper we show some results concerning the orbital stability of dnoidal standing wave solutions and orbital instability of cnoidal standing wave solutions to the following Klein–Gordon equation:
utt−uxx+u−|u|2u=0.