Negative Resistance in a Two-Dimensional System with Entropic Barrier

A phenomenon of negative resistance is found in two-dimensional bistable and periodic potentials via Langevin simulation, where output quantities for noise and signal driven system, such as the power-spectrum density modulus and the signal power amplification, can become minima at finite temperatures. In such a system, the curvature of the potential along non-transport degree of freedom at the barrier is larger than that at the local minima. The temperature-dependent effective barrier, i.e. entropic barrier, is introduced via integration over the non-transport variables. The system shows the negative resistance because of the competence between the signal and the entropic barrier.     

负二项分布类的条件概率封闭性

在研究只允许部分服务台进入休假状态的多服务台M／M／c排队系统时，我们发现了条件Erlang分布的一些有趣的性质，进一步研究我们发现相对应离散随机状态的负二项分布也具有很好的性质（概率封闭性．本文证明了一类负二项分布的概率封闭性．它们对导出复杂排队系统中离散状态下顾客等待时问分布及保险公司中破产概率上界的计算起着重要作用．     

龙须菜数量性状及AFLP分析

对6株不同的龙须菜材料进行了生长速度和光合色素含量等数量性状及AFLP分析,其中3株分别采自中国的青岛、石岛、龙须岛,2株分别来自南非和委内瑞拉,1株为青岛野生型选育品系981,以细基江蓠繁枝变型做种外对照.分析结果显示,与青岛野生型相比,981生长速度和光合色素含量发生了不同程度的改变,两者在亲缘关系极其相近的同时,又存在一定的遗传差异,本文通过AFLP标记检测到的这些差异位点很可能包含着与上述性状有关的遗传信息.4株中国龙须菜和1株南非龙须菜中,南非材料生长最快,龙须岛材料光合色素组成差异最明显,不同材料间的遗传距离有随地理间距增大而逐渐增大的趋势.此外,数量性状和AFLP分析均表明委内瑞拉材料与其他各株龙须菜间存在高度的差异,有的遗传距离甚至超过了种外对照,为将其划分到江蓠属中龙须菜以外的种增添了更加有力的新的证据.     

An optimal rigidity theorem for complete submanifolds in a sphere

It is proved that if M^n is an n-dimensional complete submanifold with parallel mean curvature vector and flat normal bundle in S^n＋p（1）, and if supM S 〈 α（n, H）, where α（n,H）=n＋n^3/2（n-1）H^2-n（n-2）/n（n-1）√n^2H^4＋4（n-1）H^2,then M^n must be the totally urnbilical sphere S^n（1/√1＋H^2）.An example to show that the pinching constant α（n, H） appears optimal is given.     

参数曲线的全局凸性判别条件

基于平面曲线的二次微商,导出了二重点的判别条件,结合参数曲线的局部凸性条件,得到了参数闭曲线的充要条件。给出了参数曲线的拐点判别条件,从而得到了参数曲线局部凸的充要条件。     

非负特征图的线性染色

如果图$G$的一个正常染色满足染任意两种颜色的顶点集合导出的子图是一些点不交的路的并,则称这个正常染色为图$G$ 的线性染色.图$G$的线性色数用lc$(G)$表示,是指$G$的所有线性染色中所用的最少颜色的个数. \qquad 证明了: 对于每一个最大度为$\Delta(G)$围长为$g(G)$的非负特征图$G$,若存在一个有序对$(\Delta,g)\in\{(13,7),(9,8),(7,9),(5,10), (3,13)\}$, 使得$G$满足$\Delta(G)\ge\Delta$且$g(G)\ge g$,则lc$(G)=\lceil \frac {\Delta(G)}2\rceil+1$.     

拟似然非线性模型的某些渐近推断:几何方法

Abstract. A modified Bates and Watts geometric framework is proposed for quasi-likelihoodnonlinear models in Euclidean inner product space. Based on the modified geometric framework,some asymptotic inference in terms of curvatures for quasi-likelihood nonlinear models is stud-ied. Several previous results for nonlinear regression models and exponential family nonlinearmodels etc. are extended to quasi-likelihood nonlinear models.     

双三次Bezier曲面片的光滑拼接

本文根据曲面的总曲率和平均曲率推导出双三次Bezier曲面片拼接的C^2连续条件。     

Solutions for the prescribing mean curvature equation

By variational methods, for a kind of Yamabe problem whose scalar curvature vanishes in the unit ball BN and on the boundary S^N-1 the mean curvature is prescribed, we construct multi-peak solutions whose maxima are located on the boundary as the parameter tends to 0^＋ under certain assumptions. We also obtain the asymptotic behaviors of the solutions.