Statistical analysis of computational docking of large compound data bases to distinct protein binding sites

The results of 16 docking simulations with rigid receptor sites and flexible ligands (∼60,000 compounds in each case) are statistically analyzed and compared. Different combinations of binding sites, scoring functions, and compound collections are used in these calculations. The docking scores are not randomly distributed over the scoring range; they follow Gaussian distributions (regardless of the binding sites), scoring functions, or screened compounds. If the docking sites are small, the Gaussian distributions are positively skewed. Peaks of the Gaussian distributions are populated with compounds having similar scores but different sizes and binding modes. These findings have implications for compound selection via computational docking. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1634–1643, 1999     

限制卖空及带交易费用的证券组合的三参数模型

本文在 (Simaan(1993) )组合选择的三参数模型的框架下 ,考虑了交易费用 ,限制卖空 ,提出了新的风险证券投资组合模型 ,并给出了风险投资最优比例的算法 .     

Fault Recognition of Rolling Bearings Based on Parameter Optimized Multi-Scale Permutation Entropy and Gath-Geva

To extract fault features of rolling bearing vibration signals precisely, a fault diagnosis method based on parameter optimized multi-scale permutation entropy (MPE) and Gath-Geva (GG) clustering is proposed. The method can select the important parameters of MPE method adaptively, overcome the disadvantages of fixed MPE parameters and greatly improve the accuracy of fault identification. Firstly, aiming at the problem of parameter determination and considering the interaction among parameters comprehensively of MPE, taking skewness of MPE as fitness function, the time series length and embedding dimension were optimized respectively by particle swarm optimization (PSO) algorithm. Then the fault features of rolling bearing were extracted by parameter optimized MPE and the standard clustering centers is obtained with GG clustering. Finally, the samples are clustered with the Euclid nearness degree to obtain recognition rate. The validity of the parameter optimization is proved by calculating the partition coefficient and average fuzzy entropy. Compared with unoptimized MPE, the propose method has a higher fault recognition rate.     

低信噪比条件下的调制方式识别

传统的调制方式识别方法通常假设接收信号是平稳随机过程,一般要在信噪比不低于10dB时才能取得较高的识别率。本文根据模拟调制信号的谱特性和谱相关特性,给出了低信噪比下的调制方式识别算法,理论分析和仿真结果表明,本文提出的算法,在低信噪比(3dB)条件下,仍然具有很高的识别率。     

Invariant tests for symmetry about an unspecified point based on the empirical characteristic function

This paper considers a flexible class of omnibus affine invariant tests for the hypothesis that a multivariate distribution is symmetric about an unspecified point. The test statistics are weighted integrals involving the imaginary part of the empirical characteristic function of suitably standardized given data, and they have an alternative representation in terms of an L²-distance of nonparametric kernel density estimators. Moreover, there is a connection with two measures of multivariate skewness. The tests are performed via a permutational procedure that conditions on the data.     

Generalized treatment of skew-cosh-Gaussian lasers for bifocal terahertz radiation

A generalized treatment of skew-cosh-Gaussian lasers with skewness parameters n and s is provided for obtaining bifocal terahertz radiation in a realistic plasma having electron-neutral collisions. In order to find and control the focusing of the radiation, a relation is established between the position of the peak of the radiation field and the parameters n and s. The significant role of these parameters in getting bifocal radiation or its conversion to unifocal radiation (or vice-versa) with a proposal for enhanced efficiency of the scheme is discussed in detail for its medical applications.     

摩擦市场条件下的双目标投资组合模型模糊优化

首先建立了摩擦市场条件下基于收益率分布偏度水平的双目标投资组合模型.在此基础上,将模糊集合的概念引入到该模型中,用模糊数学中的线性隶属函数处理了其中的风险目标和收益目标,建立了摩擦市场条件下基于收益率分布偏度水平的模糊型双目标投资组合模型.然后,针对该模型进行了新型遗传算法设计(动态遗传算法).最后用一个具体的算例给出了该模型的一个实例最优解,体现了多样化投资分散风险的组合投资原理.     

基于峰度偏度和WD-LDA的飞机目标分类方法

目前,多数的喷气发动机调制特征提取方法都是基于调制波的周期或调制线谱的谱间间隔,但该类谱估计方法往往受信噪比、脉冲重复频率及观测时间影响很难获得很好的分类性能。文中对三类飞机目标回波进行统计分析发现,其归一化幅度分布存在明显差异,据此创造性地提取出峰度偏度特征,并结合小波分解-线性判别分析处理,对目标进行分类。该特征具有很强的抗噪声能力,对脉冲重复频率和观测时间要求不高,且可通过其中一个参数去弥补另一个参数。仿真实验证明了所提方法具有很好的分类性能。     

Inferences on Correlation Coefficients in Some Classes of Nonnormal Distributions

Correlation coefficients have many applications for studying the relationship among multivariate observations. Classical inferences on correlation coefficients are mainly based on the normality assumption. This assumption is hardly realistic in the real world, which implies that the procedures on correlation coefficients used in many statistical software packages may not be relevant to most data sets in practice. However, we show that the classical procedures, possibly after simple corrections, are also valid in classes of distributions with large skewnesses and heterogeneous marginal kurtoses. A useful class of nonnormal distributions is identified for each of several types of correlation coefficients. The marginals of these distributions may include a variety of univariate distributions with different shapes. The results generalize the classical procedures to much larger classes of distributions than previously known and give a better understanding of the historical controversy regarding the behavior of the sample correlation coefficient. An implication is that one need not be worried so much by the nonnormality of data sets when using these classical procedures, providing simple corrections are evaluated and possibly undertaken.     

戈壁地区近地面折射率结构常数统计特性分析

利用温度脉动仪对大气折射率结构常数进行测量,通过在铁塔上不同测量高度架设温度脉动仪,对戈壁地区近地面层开展长期连续测量。从各测量高度折射率结构常数的累积概率、偏度与峰度、季节变化、高度经验关系等四个方面对大量实验数据统计分析,结果表明:测量地区大气折射率结构常数白天和夜间的累积概率以18m为区别界限,表现出明显的不同;所有测量高度折射率结构常数的概率分布均表现出右偏、平峰特性;季节变化对低层折射率结构常数的影响更为明显;测量地区折射率结构常数随高度变化的经验公式表明,白天折射率结构常数随高度递减接近"-2/3"指数,夜间折射率结构常数的高度变化则是表现出层次性,低层折射率结构常数随高度递减接近"-0.16"指数,而高层变化则接近"-1.05"指数。