MATHEMATICAL ANALYSIS OF THE COLLAPSE IN BOSE-EINSTEIN CONDENSATE

In this article, the authors consider the collapse solutions of Cauchy problem for the nonlinear Schrdinger equation iψt + 1/2 △ψ - 1/2 ω2|x|2ψ + |ψ|2ψ = 0, x ∈ R2, which models the Bose-Einstein condensate with attractive interactions. The authors establish the lower bound of collapse rate as t → T . Furthermore, the L2-concentration property of the radially symmetric collapse solutions is obtained.     

基于欧姆加热模型的一类非局部双曲方程解的渐近性态

In this paper,the asymptotic behavior of a non-local hyperbolic problem modelling Ohmic heating is studied.It is found that the behavior of the solution of the hyperbolic problem only has three cases:the solution is globally bounded and the unique steady state is globally asymptotically stable;the solution is infinite when t→∞;the solution blows up.If the solution blows up,the blow-up is uniform on any compact subsets of(0,1] and the blow-up rate is lim t → T*-u(x,t)(T*-t)1/α+βp-1=(α+βp-1/1-α)1/1-α-βp,where T* is the blow-up time.     

关于含临界指数的p-平均曲率算子

This paper is concerned with the existence of positive solutions of the following Dirichlet problem for p-mean curvature operator with critical exponent: -div((1 |▽u|~2)(p-2)/2▽u)=λu~(p*-1) μu~(q-1),u＞0,x∈Ω, u=0,x∈■Ω, where u∈W_0~(1,p)(Ω),Ωis a bounded domain in R~N(N＞p＞1)with smooth boundary ■Ω,2＜=p＜=q＜=P~*,P~*=(Np)/(N-p),λ,P＞0.It reaches the conclusions that this problem has at least one positive solution in the different cases.It is discussed the existences of positive solutions of the Dirichlet problem for the p-mean curvature operator with critical exponent by using Nehari-type duality property firstly.As p=2,q=p,the result is correspond to that of Laplace operator.     

A better semi-online algorithm for Q3/s1 = s2≤ s3/Cmin with the known largest size

This paper investigates the semi-online machine covering problem on three special uniform machines with the known largest size. Denote by sj the speed of each machine, j = 1, 2, 3. Assume 0 < s1 = s2 = r ≤ t = s3, and let s = t/r be the speed ratio. An algorithm with competitive ratio max{2, (3s+6)/(s+6) } is presented. We also show the lower bound is at least max{2, (3s)/(s+6)}. For s ≤ 6, the algorithm is an optimal algorithm with the competitive ratio 2. Besides, its overall competitive ratio is 3 which matches the overall lower bound. The algorithm and the lower bound in this paper improve the results of Luo and Sun.     

On the Best Degree of Approximation by Euler (E,q)-Means

Let f(x)∈L_(2π) and its Fourier series by f(x)～α_0/2+sum from n=1 to ∞(α_ncosnx+b_nsinx)≡sum from n=0 to ∞(A_n(x)). Denote by S_n (f,x) its partial sums and by E_n~q(f,x) its Euler (E, q)-means, i. e. E_n~q(f,x)=1/(1+q)~π sum from m=0 to n((?)q~(n-m)S_m(f,x)), with q≥0 (E_n~0≡S_n). In [1] Holland and Sahney proved the following theorem. THEOREM A Ifω(f,t) is the modulus of continuity of f∈C_(2π), then the degree of approximation of f by the (E,q)-means of f is givens by##特殊公式未编改     

Gradient Estimates of Solutions to the Conductivity Problem with Flatter Insulators

We study the insulated conductivity problem with inclusions embedded in a bounded domain in R~n. When the distance of inclusions, denoted by ε, goes to 0, the gradient of solutions may blow up. When two inclusions are strictly convex, it was known that an upper bound of the blow-up rate is of order ε~(-1/2) for n = 2, and is of order ε~(-1/2+β)for some β 0 when dimension n ≥ 3. In this paper, we generalize the above results for insulators with flatter boundaries near touching points.     

MULTIPLICITY OF POSITIVE SOLUTIONS FOR A NONLOCAL ELLIPTIC PROBLEM INVOLVING CRITICAL SOBOLEV-HARDY EXPONENTS AND CONCAVE-CONVEX NONLINEARITIES

In this article, we study the following critical problem involving the fractional Laplacian:■where ? ? R~N(N α) is a bounded smooth domain containing the origin, α∈(0, 2),0 ≤ s, t α, 1 ≤ q 2, λ 0, 2*_α(t) =2(N-t)/(N-α) is the fractional critical Sobolev-Hardy exponent, 0 ≤γ γH, and γH is the sharp constant of the Sobolev-Hardy inequality. We deal with the existence of multiple solutions for the above problem by means of variational methods and analytic techniques.     

带有临界Sobolev指数的奇异双调和问题

LetΩR~N be a smooth bounded domain such that 0∈Ω,N≥5,2~*:=(2N)/(N-4) is the critical Sobolev exponent,and f(x) is a given function.By using the variational methods, the paper proves the existence of solutions for the singular critical in the homogeneous problemΔ~u-μu/(|x|~4)=|u|~(2~*-2)u f(x) with Dirichlet boundary condition on Ωunder some assumptions on f(x) andμ.     

THE STABILITY OF STATIONARY SOLUTION FOR OUTFLOW PROBLEM ON THE NAVIER-STOKES-POISSON SYSTEM

In this article, we are concerned with the stability of stationary solution for outflow problem on the Navier-Stokes-Poisson system. We obtain the unique existence and the asymptotic stability of stationary solution. Moreover, the convergence rate of solution towards stationary solution is obtained. Precisely, if an initial perturbation decays with the algebraic or the exponential rate in space, the solution converges to the corresponding stationary solution as time tends to infinity with the algebraic or the exponential rate in time. The proof is based on the weighted energy method by taking into account the effect of the self-consistent electric field on the viscous compressible fluid.     

ON THE CENTRAL RELAXING SCHEMES I:SINGLE CONSERVATION LAWS

1. IntroductionIn [6], Jin and adn constructed a class of uPWind relaxing schemes for nonlinearconservation lawswith initial data u(0, x) ~ "o(x), x ~ (xl, ...t -cd), by using the idea of the local relaxation approximation [2,3,6,10].The relaxing scheme is obtained in the following way: A linear hyperbolic systemwith a stiff source term is first constructed to approximate the original equation (1.1)with a small dissipative correction. Then this linear hyperbolic system is solved easilyby und…     

稳定性理論中第一临界情形的微分方程与微分差分方程的等价性問題

<正> §1.問題与方法.在[1]中提出了等价性問題,并对于一般n的情形作了系統的研究.本文是处理在第一临界情形下的微分方程与微分差分方程的等价性問題. 問題是研究微分方程組     

求解Riesz空间分数阶扩散方程的一种新的数值方法

本文利用Diethelm方法构造了一种逼近Riesz空间分数阶导数的O（△x^3-α）格式,其中1 < α < 2,△x是空间步长.进一步对一阶时间导数采用Crank-Nicolson方法离散,得到了求解Riesz空间分数阶扩散方程的一种新的有限差分格式,并用矩阵方法证明了稳定性和收敛性,其误差估计为O（△t²+△x^3-α）,其中△t为时间步长.最后,数值算例验证了差分格式的正确性和有效性.     

解二维抛物型方程的高精度显式差分格式

<正> 1 引言从扩散、渗流、热传导等问题中可以提出很多抛物型方程。对于一维的抛物型方程u_1=σu_(xx)(σ>0),文[1]给出了一个截断误差为O(△t~2+△x~4)的高精度显式差分格式,对于二维的抛物型方程u_t=σ(u_(xx)+u_(yy))(σ>0),文[2]给出了截断误差为O(△t~2+△x~2+△y~2)的绝对稳定的显     

关于三次样条函数导数的某些不等式

设△:。~x。相似文献   

关于用多维样条逼近的饱和度

<正> 作者在工作[1]中,研究了一维样条逼近的饱和度问题,得到了下述定理: 定理A 设{△_k}是区间[a,b]的一分划序列,‖△_k‖→0(k→∞),R_(△k)≤β<∞(k=1,2,…),若f(x)∈c~n[a,b],S_(△_k)(x)是(n-1)次多项式样条,如果 对任一p成立,(p=0,1,…,n)则 D~nf(x)≡0. 本文是[1]的续篇,对多维样条进行研究,可得一些类似的结果,为明确起见,我们仅对二维情形进行讨论.     

稳定性理论中的微分方程与微分差分方程的等价性问题

<正> §1.问题与方法 在[1]中提出了等价性问题,并对于 n=1 的情形作了系统的解决.本文是处理一般 n 的情形.问题是研究微分方程组与微分差分方程组之间在稳定性部题中的等价性.此地 a_(ij)及b_(ij)等均为已给常数;τ_(ij)(t)或为非负的实常     

临界或超临界增长分数阶Schrodinger-Poisson方程正解的存在性

本文研究如下分数阶Schrodinger-Poisson方程{(-△)^su+Vx(u)+K(x)φu=f(u)+λ|u|^q-2ux∈R³,(-△)^tφ=K(x)u²,x∈R³其中S∈(3/4,1),t∈(0,1),f是在原点超线性无穷远次临界的连续非线性项,指数q≥2_s^*=6/3-2x.当λ>0充分小时,我们利用变分方法证明上述问题正解的存在性.本文的主要贡献是处理了超临界情形.     

奇异半线性反应扩散方程初值问题的一些注记

考虑下述奇异半线性反应扩散方程初值问题(()-1-t△u=ut+f(x),t＞0,x∈RN lim u(t,x)=0,x∈RN t→0=)其中r＞0,△=∑( )/( )x2i,f(x)非负且f(x)∈L∞(RN).首先利用增算子不动点定理,重新证明了IVP在(0,+∞)上至少存在一个非负解,并给出了IVP解的迭代逼近序列.其次获得了一个有关IVP(1)正解的无限增长性的结果.最后,证明了当r＞1时,去掉条件1/r-1≥n/2,IVP的正解u(t)同样会产生爆破.研究结果表明情形limut→+∞(t,x)=+∞不会出现.     

一类抛物型方程系数反问题的分裂算法

考虑利用终端时刻的温度u(x,T)=Z_T(x)反演热传导方程u_t-a~2u_(xx) q(x)u=0,x∈(0,1)中的未知系数q(x)的反问题.通过引进变换v(x,t)=(u_t(x,t)/u(x,t))将此非线性不适定问题的求解分解为两步.首先利用输入数据迭代求解一个非线性的正问题(该过程独立于未知系数),得到其迭代解v~(k)(x,t).其次利用q(x)与v(x,t)的关系式求出q(x)的近似解.对提出的反演方法,证明了采用的变换的可行性,得到了原反问题与由变换后的非线性正问题反演q(x)的等价性并且证明了迭代解的收敛性,给出了收敛速度.数值结果表明了该方法的有效性.