科学配置合并组建高校的文献信息资源

组建高校面临着全校文献信息资源的重组和合理配置 ,针对合并组建高校的文献信息资源重组和配置采取正确的对策和措施 ,发挥数字化文献信息资源的作用 ,从而充分发挥合并组建高校文献信息资源的整体效益     

On Rates of Convergence for Bayesian Density Estimation

Abstract.  We consider the problem of estimating a compactly supported density taking a Bayesian nonparametric approach. We define a Dirichlet mixture prior that, while selecting piecewise constant densities, has full support on the Hellinger metric space of all commonly dominated probability measures on a known bounded interval. We derive pointwise rates of convergence for the posterior expected density by studying the speed at which the posterior mass accumulates on shrinking Hellinger neighbourhoods of the sampling density. If the data are sampled from a strictly positive, α -Hölderian density, with α  ∈ ( 0,1] , then the optimal convergence rate n^{− α / (2 α +1)} is obtained up to a logarithmic factor. Smoothing histograms by polygons, a continuous piecewise linear estimator is obtained that for twice continuously differentiable, strictly positive densities satisfying boundary conditions attains a rate comparable up to a logarithmic factor to the convergence rate n ^−4/5 for integrated mean squared error of kernel type density estimators.     

A bayesian estimator for the dependence function of a bivariate extreme‐value distribution

Any continuous bivariate distribution can be expressed in terms of its margins and a unique copula. In the case of extreme‐value distributions, the copula is characterized by a dependence function while each margin depends on three parameters. The authors propose a Bayesian approach for the simultaneous estimation of the dependence function and the parameters defining the margins. They describe a nonparametric model for the dependence function and a reversible jump Markov chain Monte Carlo algorithm for the computation of the Bayesian estimator. They show through simulations that their estimator has a smaller mean integrated squared error than classical nonparametric estimators, especially in small samples. They illustrate their approach on a hydrological data set.     

鲁迅作品中的祭祀仪式原型

鲁迅的许多作品是经过置换变形的祭祀仪式原型。置换变形的关键在于对主人公地位的处理。这种处理方式显现出鲁迅对于启蒙的一个完整的思考,祭祀仪式原型投射了鲁迅自身体味到的悲剧意识。     

土家族历史上的传统分配和交换制度研究

土家族长期繁衍生息于湘鄂渝黔边的武陵山区，受这里的自然环境和历史上生产力状况的影响，形成了这个民族在生产中的许多特点。尤其是土家族的传统分配和交换制度在阶级社会中仍然保留着原始民族的一般互惠性分配方式的遗迹，在封建社会的产品交换中仍然表现出浓厚的等价互惠性。但是，由于阶级的出现，传统的分配和交换已打上了阶级压迫的烙印。     

“5．12”汶川大地震受灾人口特征与生存环境变化分析

“5．12”汶川大地震造成10万余平方公里的破坏性区域，造成69227人遇难、17923人失踪和374643人受伤，受灾人口（重灾区）2792万人。8．0级地震所释放的能量，在一定程度上改变了受灾人口所依存的自然环境和人文生态环境。本文以四川地震重灾区为研究单元，在系统分析受灾人口所依存的自然生态环境、居住（建筑空间）环境、人文生态环境、基础设施以及产业发展环境及其发展变化的基础上，析出重灾区内人口生存空间进一步缩小和调整人口分布的结论。在此基础上。提出重灾区在恢复重建中的人口分布调整建议。     

水资源跨流域配置的经济学分析

由于我国水资源空间分布不均匀的突出特点 ,大型跨流域调水工程已经成为我国国民经济可持续发展的重要支撑。文章从水资源的经济特点出发 ,结合南水北调中线工程 ,对水资源跨流域配置的市场供求、成本收益等资源经济学问题进行了分析 ,并对社会主义市场经济条件下水资源跨流域配置的利益分配机制进行了探讨     

A note on LeCam’s bound for the distance between the Poisson binomial and the Poisson distribution

n possibly different success probabilities p ₁, p ₂, ..., p _n is frequently approximated by a Poisson distribution with parameter λ = p ₁ + p ₂ + ... + p _n . LeCam's bound p ² ₁ + p ² ₂ + ... + p _n ² for the total variation distance between both distributions is particularly useful provided the success probabilities are small. The paper presents an improved version of LeCam's bound if a generalized d-dimensional Poisson binomial distribution is to be approximated by a compound Poisson distribution. Received: May 10, 2000; revised version: January 15, 2001     

随机变量投影的一种应用

利用随机变量的投影关系,定义了偏方差矩阵,从而导出了逆方差阵元素的一种形式在随机变量是正态的条件,它为判别条件独立性有方便的操作办法。     

用Powell法求颗粒尺寸分布

本文用最优化理论中的Powell直接法求激光粒度仪中的颗粒尺寸分布。数值模拟及对标准颗粒的实测表明,该算法的计算精度高,能较好地解决粒度仪通常存在的计算结果随初始设定值变化的多值性问题。