Free cooling phase-diagram of hard-spheres with short- and long-range interactions

We study the stability, the clustering and the phase-diagram of free cooling granular gases. The systems consist of mono-disperse particles with additional non-contact (long-range) interactions, and are simulated here by the event-driven molecular dynamics algorithm with discrete (short-range shoulders or wells) potentials (in both 2D and 3D). Astonishingly good agreement is found with a mean field theory, where only the energy dissipation term is modified to account for both repulsive or attractive non-contact interactions. Attractive potentials enhance cooling and structure formation (clustering), whereas repulsive potentials reduce it, as intuition suggests. The system evolution is controlled by a single parameter: the non-contact potential strength scaled by the fluctuation kinetic energy (granular temperature). When this is small, as expected, the classical homogeneous cooling state is found. However, if the effective dissipation is strong enough, structure formation proceeds, before (in the repulsive case) non-contact forces get strong enough to undo the clustering (due to the ongoing dissipation of granular temperature). For both repulsive and attractive potentials, in the homogeneous regime, the cooling shows a universal behaviour when the (inverse) control parameter is used as evolution variable instead of time. The transition to a non-homogeneous regime, as predicted by stability analysis, is affected by both dissipation and potential strength. This can be cast into a phase diagram where the system changes with time, which leaves open many challenges for future research.     

Holder continuity for a class of X-elliptic equations with singular lower order term

The regularity for a class of X-elliptic equations with lower order term Lu+vu=-mΣi,j=1X*j(aij(x)Xiu)+vu=μis studied, where X = {X1,…, Xm} is a family of locally Lipschitz continuous vector fields, v is in certain Morrey type space and μ a nonnegative Radon measure. The HSlder continuity of the solution is proved when μ satisfies suitable growth condition, and a converse result on the estimate of # is obtained when u is in certain HSlder class.     

单障碍问题区域分解法的单调收敛性与收敛速度估计

本文我们考虑一类典型的椭圆型算子的障碍问题的区域分解算法,分析算法的单调收敛性并给出相应的收敛速度估计.障碍问题有着重要的物理背景（参见[3,9]）.近些年来,有关障碍问题的区域分解法方面的研究已经有一些成果.关于线性算子情形,读者可参看[1,2,5,7,8,10,12,13,14,15,17]等文献,而对于非线性算子情形,读者可参看[4,6,16,18].在这些文献中,已经有部分涉及到算法的收敛速度估计.例如,文[15,16]给出了有限元区域分解算法的迭代误差的渐近最大模估计,文[13]给出了求解具M-阵的有限维互补问题     

半线性椭圆方程正解存在性

本文讨论了临界指数情形半线性椭圆方程-Δu+α(x)u=b(x)u~p+g(x,u)在R~n中的正解存在性。     

关于带梯度的波动方程解的blow—up性质

本文讨论了一个带有梯度的非线性波动方程解的爆破性质,证明了解在有限时间内爆破,推广了文[1]的结果.     

具有"积分小”系数的一阶非线性中立型微分方程的振动性

运用一定的技巧,建立了一阶非线性中立型徽分方程[x(t)-P(t)x(t-r)]′+(?)signx(t -δ_i)=0的所有解振动的新的充分条件,推广和改进了已知文献中的某些已知结论.     

一类非线性反应扩散方程组的有限元分析

菸屏抗娴耐ǘ嘶故侵苟耍蟛饬康亩急匦胧撬堑闹芯叮皇堑ヒ恢芯丁Ｂ菸屏抗娴闹芯叮ǔ２捎萌敕ú饬俊？墒牵敕ú獬隽恐挡环螱B／T14791－93螺纹中径的定义。三针法直接测出的是螺纹量规的单一中径。按GB／T14791－93要求,螺纹的中径是一假想圆柱的直径,该圆柱的母线通过牙型上沟槽和凸起宽度相等的地方。一般应该用三针法测出单一中径,再在工具显微镜上测出螺距的实际偏差值,然后按下式计算出螺纹量规的中径氖当平獾拇嬖谖ㄒ恍约捌湮蟛钭钣牛葉（１）模和最优Ｌ~（２）模估计结果．在　２中,建立（１）的交替…     

带随机效应非线性模型的影响分析

Abstract. In this paper,a unified diagnostic method for the nonlinear models with random ef-fects based upon the joint likelihood given by Robinson in 1991 is presented. It is shown that thecase deletion model is equivalent to the mean shift outlier model. From this point of view ,sever-al diagnostic measures, such as Cook distance, score statistics are derived. The local influencemeasure of Cook is also presented. A numerical example illustrates that the method is avail-able     

弱耗散非线性浅水波方程周期柯西问题

建立了弱耗散非线性浅水波方程的局部适定性,对于不同的初始值,我们分别得到了解的整体存在性和解的爆破。