非正则型跃度问题

苏联数学家1972年在苏联高等学校通报上(参看[1])讨论过下面形式的跃度问题     

论高速运动物体速度合成的非交换性

一般有关相对论力学的教科书上并不提到速度合成问题［１］，有的书谈到速度合成时往往只给出牵连速度Ｖ沿ｘ轴特定方向的速度合成公式［２］［３］［４］，而没有给出一般的速度合成公式．本文简明地推导了一般速度合成公式，并阐述了狭义相对论中的速度合成的非交换性的本质．     

广义Bianchi恒等式的某些应用

本文给出由非不变性拉氏量导致的广义Bianchi恒等式的若干应用。导出强守恒律,用于某些场论,得到相应的弱守恒律,讨论了非不变拉氏量系统的Dirac约束。     

STEADY-STATE SOLUTIONS FOR A ONE-DIMENSIONAL NONISENTROPIC HYDRODYNAMIC MODEL WITH NON-CONSTANT LATTICE TEMPERATURE

A one-dimensional stationary nonisentropic hydrodynamic model for semiconductor devices with non-constant lattice temperature is studied. This model consists of the equations for the electron density, the electron current density and electron temperature, coupled with the Poisson equation of the electrostatic potential in a bounded interval supplemented with proper boundary conditions. The existence and uniqueness of a strong subsonic steady-state solution with positive particle density and positive temperature is established. The proof is based on the fixed-point arguments, the Stampacchia truncation methods, and the basic energy estimates.     

Brass悖论及其算法

简要讨论了Brass悖论并给出了计算机算法。算法模拟了非合作粒子通过自身的经验学习寻找最佳路径的过程。经过一段时间的演化之后,系统很快的达到Nash平衡。计算得到的分配结果与实证结果基本一致。     

局部对称共形平坦黎曼流形中带有平坦法丛的子流形

设M~(n p)是n p维共形平坦黎曼流形,且它的黎曼张量R_(tjkl)之共变导微▽R_(tjkl)=0,则称M~(n p)为局部对称共形平坦黎曼流形。 本文证得:若V~n(n≥2)是局部对称共形平坦黎曼流形M~(n p)的n维紧致无边子流形,它具有平坦法丛,若V~n在任一点上的截面曲率均大于T_c-t_c/2(n p-2),这里T_c、t_c分别是M~(n p)的Ricci曲率在该点的上、下确界,则V~n一定是M~(n p)的n 1维全测地子流形M~(n 1)之超曲面。     

逆p·n·p·矩阵的表征

一个n阶实方阵A,若其各阶主子式皆非正,则称A为p.n.p.矩阵,记作A∈PNP;特别地,若A∈NP且各阶主子式皆负,则称A为p.n.矩阵,记作A∈PN进一步,若n阶实方阵A非奇异,且A^-1∈PNP,则称A为逆p.n.p.矩阵,记作A∈IPNP;特别地,若A^-1∈PN,则称A为逆p.n.矩阵,记作A∈IPN。     

状态与输出均有滞后的不确定广义系统的非脆弱H∞控制

针对带有状态滞后的连续广义系统,给出了其广义二次稳定且满足一定H∞性能的充分条件,并利用线性矩阵不等式技术,得到了带有状态滞后和不确定性的连续广义系统的含有控制器增益扰动的鲁棒H∞控制器的设计方法.最后,所举数值例子说明了该方法的应用.     

NONLINEAR EVOLUTION SYSTEMS AND GREEN’S FUNCTION

In this paper, we will introduce how to apply Green’s function method to get the pointwise estimates for the solutions of Cauchy problem of nonlinear evolution equations with dissipative structure. First of all, we introduce the pointwise estimates of the time-asymptotic shape of the solutions of the isentropic Navier-Stokes equations and show to exhibit the generalized Huygen’s principle. Then, for other nonlinear dissipative evolution equations, we will only introduce the result and give some brief explanations. Our approach is based on the detailed analysis of the Green’s function of the linearized system and micro-local analysis, such as frequency decomposition and so on.