Multivariate distributions defined in terms of contours

The paper deals with the problem of using contours as the basis for defining probability distributions. First, the most general probability densities with given contours are obtained and the particular cases of circular and elliptical contours are dealt with. It is shown that the so-called elliptically contoured distributions do not include all possible cases. Next, the case of contours defined by polar coordinates is analyzed including its simulation and parameter estimation. Finally, the case of cumulative distribution functions with given contours is discussed. Several examples are used for illustrative purposes.     

KS型议程的行波解讨论

本文利用齐次平衡法确定了KS型方程双曲正切函数解的参数所满足的方程组，并且展开相关讨论，如给出了解的几种特殊情况及双曲正切函数法的适定条件等，为非线性发展方程的行波解（孤立波解）的求出给出了具有参考价值的理论与实例。所采用的方法具有普遍性。     

一类变系数高阶线性齐次微分方程解的探求(英文)

本文对系数全为多项式和广义多项式的n阶线性齐次微分方程引入特征方程的概念。给出了具有指数型解的充要条件，推广了经典的常系数线性方程和著名的Euler方程的的解法，为求解变系数线性微分方程提供了有效的方法。     

生产函数与成本函数的关系研究

本文给出了生产函数与成本函数之间的一般关系,并证明齐次生产函数与齐次成本函数之间存在着一种齐次对应关系:齐次生产函数在厂商的成本最小化决策下必然产生齐次的成本函数且齐次成本函数必然产生对应于齐次的生产函数。     

A second order model for cylindrical data

Modeling cylindrical data, comprised of a linear component and a directional component, can be done using Fourier series expansions if we consider the conditional distribution of the linear component given the angular component. This paper presents the second order model which is a natural extension of the Mardia and Sutton (1978) first order model. This model can be parameterized either in polar or Cartesian coordinates, and allows for parameter estimation using standard multiple linear regression. Characteristic of the new model, how to compare the adequacy of the fit for first and second order models, and an example involving wind direction and temperature are presented.     

Discriminant coordinates analysis for multivariate functional data

Abstract

One of the basic statistical methods of dimensionality reduction is analysis of discriminant coordinates given by Fisher (1936 Fisher, R. A. 1936. The use of multiple measurements in taxonomic problem. Annals of Eugenics 7 (2):179–88. doi:10.1111/j.1469-1809.1936.tb02137.x.[Crossref] , [Google Scholar]) and Rao (1948). The space of discriminant coordinates is a space convenient for presenting multidimensional data originating from multiple groups and for the use of various classification methods (methods of discriminant analysis). In the present paper, we adapt the classical discriminant coordinates analysis to multivariate functional data. The theory has been applied to analysis of textural properties of apples of six varieties, measured over a period of 180?days, stored in two types of refrigeration chamber.     

电子商务市场产品多元化战略的销售绩效及驱动因素研究

结合电子商务市场特征,从理论方面分析电子商务市场产品多元化战略的驱动因素及其销售绩效,利用正则表达式等数据挖掘技术形成电子商务市场的面板数据库,并对相关研究假设进行实证检验。结果表明：在电子商务市场上,产品多元化战略与企业销售绩效正相关,而市场同质化竞争程度与产品多元化战略负相关,企业经营时间、顾客好评率抑制了企业对产品多元化战略的选择。研究结论对于电子商务市场的企业产品多元化战略选择具有重要参考意义。     

我国网络舆情研究的进展分析（2014—2018） ——基于战略坐标图

为揭示我国网络舆情研究领域的热点主题及其之间的关联,提出现存的问题及未来的趋势,抓取了2014—2018年CSSCI来源期刊刊载的网络舆情相关文章的关键词,构建高频词的共词矩阵,使用聚类分析将高频词聚集成7个类团,并采用战略坐标图揭示类团内部及类团之间的关系。研究发现,我国网络舆情研究主要集中在舆情传播的仿真建模,基于大数据的微博网络舆情传播模式,突发事件、公共热点事件和群体性事件的网络舆情演化等7个领域。我国网络舆情研究存在对舆情传播中个体特征的研究较少,对微信以及移动互联网环境中舆情的研究较少等问题。移动互联网环境中网络舆情的传播与演化、个体情绪认知对网络舆情传播的影响等是潜在的重要研究主题。     

均匀场中部分球的静电问题和应用

对于某些微波场的问题,本文利用在均匀静电场中导物体的微扰效应作为近似解,解决了在均匀场中不完全球形电极的这样一个问题.