Extreme shape analysis

Summary.  We consider the analysis of extreme shapes rather than the more usual mean- and variance-based shape analysis. In particular, we consider extreme shape analysis in two applications: human muscle fibre images, where we compare healthy and diseased muscles, and temporal sequences of DNA shapes from molecular dynamics simulations. One feature of the shape space is that it is bounded, so we consider estimators which use prior knowledge of the upper bound when present. Peaks-over-threshold methods and maximum-likelihood-based inference are used. We introduce fixed end point and constrained maximum likelihood estimators, and we discuss their asymptotic properties for large samples. It is shown that in some cases the constrained estimators have half the mean-square error of the unconstrained maximum likelihood estimators. The new estimators are applied to the muscle and DNA data, and practical conclusions are given.     

2+1维Broer-Kaup方程推广的Painlevé非标准截断展开和精确解

利用基于Painleve奇性分析方法的Pickering的非标准截断展开方法,并借助于Maple软件,得到了一个2+1维Broer-Kaup方程的一些孤子解.     

油气资源评价中风险分析方法探讨

资源风险分析是油气资源评价中不可缺少的重要组成部分。我国油气资源评价往往注重资源量的定量测算 ,而资源风险分析却相对薄弱 ,有的甚至被忽略。本文系统地介绍了地质风险概率法、模糊集合综合评判法和最小经济储量规模法的基本原理及相关数学模型 ,并结合实例分析 ,对油气资源的地质风险和经济风险进行研究 ,以优选勘探目标 ,提高勘探成功率。     

相变材料的平面轴对称问题(Ⅱ)--S-H-Y模型条件下的平面应力轴对称问题

利用宏观唯象理论得出的相材料的屈服函数，推导出在S-H-Y模型条件下相变材料平面应力轴对称问题的弹塑性解，从而定量的描述相应材料应力、应变、变形及破坏的关系．     

Statistical models for the analysis of controlled trials on acute migraine

Specific efficacy criteria were defined by the International Headache Society for controlled clinical trials on acute migraine. They are derived from the pain profile and the timing of rescue medication intake. We present a methodology to improve the analysis of such trials. Instead of analysing each endpoint separately, we model the joint distribution and derive success rates in any criteria as predictions. We use cumulative regression models for each response at a time and a multivariate normal copula to model the dependence between responses. Parameters are estimated using maximum likelihood. Benefits of the method include a reduction in the number of tests performed and an increase in their power. The method is well suited to dose–response trials from which predictions can be used to select doses and optimize the design of subsequent trials. More generally, our method permits a very flexible modelling of longitudinal series of ordinal data. Copyright © 2003 John Wiley & Sons, Ltd.     

大战略是清王朝历史命运的制动力

作为一种制动力 ,大战略是通过对全部动力系统的协调、支配、控制、运筹等全方位的活动 ,产生影响和决定历史演化方向、社会发展状况的力量。清王朝的政权兴亡命运和清代社会发展演化的曲线为大战略的设计和运筹的状况所决定 ,既受到大战略实施主体所在集团利益和阶级利益的直接影响 ,也受到历史文化、社会环境以及最高决策者素质等因素的影响。     

基于一元三次方程求解的地心坐标至大地坐标的严密变换

基于一元三次方程的求解，给出了地心坐标向大地坐标转换的严密计算公式，并用算例说明了其正确性。本文提出的方法完全可以替代现有的以数值迭代计算为基础的转换方法。     

电子轨道自旋角动量耦合的克莱布希-高登系数的计算

对于角动量耦合的克莱布希-高登系数，因为计算非常复杂，量子力学教材上一般不作计算，而由查表确定．以轨道自旋耦合为例，计算了它的克莱布希-高登系数．     

Jacobi椭圆函数展开法的应用

通过对Jacobi椭圆函数展开法适用条件——秩的分析，求解了Joseph—Egri方程的精确周期解，并且对椭圆函数展开法进行适当的扩充以求解变系数KdV方程的精确周期解．此方法同样适用于其它具有变系数的非线性演化方程（NLEEs）．     

一类二阶拟线性时滞差分方程的非振动性定理

研究了一类二阶拟线性时滞差分方程的渐近性,并给出了特殊情况下,此方程存在Ac∞,A0c型非振动解的充要条件以及存在A0∞非振动解的充分条件.