中国人口学科国际化水平及其影响因素

国际化是学科成熟与发展的一个重要指标。但是作为世界人口第一大国,中国人口学科的国际化并没有发展到一个相对应的水平。在界定了学科国际化概念的基础上,借助问卷调查数据来分析中国人口学科国际化的现状,探讨中国人口科学继续与国际学界融合所面临的困难及其主要原因。结果表明,中国人口学的国际化明显处于不断萎缩的态势,其直接动因和深层次缘由分别是整个人口学界的国际化意识与能力的减弱,以及人口学科文化与制度本身存在的缺陷。加强国际化的学科文化建设与建立相配套的学科制度是提高中国人口学科国际化水平的重要途径。     

Parameters estimation for weibull distributed lifetimes under progressive censoring with random removeals

This paper considers the estimation problem when lifetimes are Weibull distributed and are collected under a Type-II progressive censoring with random removals, where the number of units removed at each failure time follows a uniform discrete distribution. The expected time of this censoring plan is discussed and compared numerically to that under a Type II censoring without removal. Maximum likelihood estimator of the parameters and their asymptotic variances are derived.     

Exact sample size determination in a weibull test plan when there is time censoring

Engineers who conduct reliability tests need to choose the sample size when designing a test plan. The model parameters and quantiles are the typical quantities of interest. The large-sample procedure relies on the property that the distribution of the t -like quantities is close to the standard normal in large samples. In this paper, we use a new procedure based on both simulation and asymptotic theory to determine the sample size for a test plan. Unlike the complete data case, the t -like quantities are not pivotal quantities in general when data are time censored. However we show that the distribution of the t -like quantities only depend on the expected proportion failing and obtain the distributions by simulation for both complete and time censoring case when data follow Weibull distribution. We find that the large-sample procedure usually underestimates the sample size even when it is said to be 200 or more. The sample size given by the proposed procedure insures the requested nominal accuracy and confidence of the estimation when the test plan results in complete or time censored data. Some useful figures displaying the required sample size for the new procedure are also presented.     

论水平扭剪应力场对大裂缝系统的控制

本文根据地质力学和岩体结构力学原理，探讨水平扭剪应力场在大裂缝系统形成、转化和分布中的重要控制作用及其物理模型．文中认为，大裂缝系统是较大的直压型裂缝网络与扭剪型裂缝网络叠加的产物，主要分布在较强的水平扭剪应力和术平直压应力复合作用的区块；水平扭剪应力场是改造和控制大裂缝网络结构异向性的最重要因素。这为研究和勘探较大的隐伏裂缝系统，提供了新的成藏模式和理论依据。     

Discrete Linnik Weibull distribution

Abstract

We introduce a new family of distributions using truncated discrete Linnik distribution. This family is a rich family of distributions which includes many important families of distributions such as Marshall–Olkin family of distributions, family of distributions generated through truncated negative binomial distribution, family of distributions generated through truncated discrete Mittag–Leffler distribution etc. Some properties of the new family of distributions are derived. A particular case of the family, a five parameter generalization of Weibull distribution, namely discrete Linnik Weibull distribution is given special attention. This distribution is a generalization of many distributions, such as extended exponentiated Weibull, exponentiated Weibull, Weibull truncated negative binomial, generalized exponential truncated negative binomial, Marshall-Olkin extended Weibull, Marshall–Olkin generalized exponential, exponential truncated negative binomial, Marshall–Olkin exponential and generalized exponential. The shape properties, moments, median, distribution of order statistics, stochastic ordering and stress–strength properties of the new generalized Weibull distribution are derived. The unknown parameters of the distribution are estimated using maximum likelihood method. The discrete Linnik Weibull distribution is fitted to a survival time data set and it is shown that the distribution is more appropriate than other competitive models.     

朝鲜族人口自然增长率下降对发展的影响

本文分析了朝鲜族人口减少的主要原因及负面影响,并提出了解决的对策.     

试论城市化进程中的民族关系--以对临夏市的调查为视点

临夏市作为西北民族地区的一个小城市,在城市化进程中,其民族关系也会受到影响.针对临夏市的实际情况及学术界的研究现状,我们选取临夏市城市化进程中变化较大的几个变量,即民族居住格局的变迁、人口流动的影响、民族通婚的增减以及宗教因素,作为研究重点来衡量城市化进程中的民族关系.在此基础上得出临夏市各民族之间的关系总体上是平等、团结、互助、合作的社会主义新型民族关系,和谐平等的民族关系占据了主导地位的结论,并归纳出城市化进程中临夏市的民族关系具有主从性、敏感性、易发性、历史性、隐蔽性、复杂性等特点,最后提出临夏市各族群众必须解决自身的定位问题,建立临夏市和谐民族关系的良性运转机制.     

宋金时期安多藏族人口的数据与统计——兼谈宋金时期安多藏族人口发展的原因

宋金时期,今青海、甘肃及四川西北部的安多地区,是藏族居住的一个重要区域,分布着大量藏族人口。本文拟对宋金文献中出现的安多藏族人口数据进行深入细致的分析,力求对当时安多藏族人口数据及人口发展的原因得出与史实相符的认识。     

蒙·元时期的波斯与中国

蒙·元时期蒙古人的西征和扩张以及由此形成的政治格局,致使亚欧陆地境域获得全面开放,加之东西方驿站通道的设置及伊利汗国与元廷始终保持着陆、海两道的密切联系,乃使这一时期中国与波斯的交往,较之以往大为拓展。而这时特殊的政治环境,又为大量波斯地区的回回人自觉或不自觉地东向迁移提供了便捷的条件。可以说,蒙·元时期中国与波斯间的人口往来,始终未曾间断。而随着他们的东来,波斯地区的学术、技艺等亦随之传播到元朝,因而大大丰富了中国文化的内容,并对元代中国文化产生了重大影响。     

对临夏人口问题的研究与思考

临夏人多地少,人口问题越来越突出,人口与资源、环境之间的矛盾愈来愈严重。本文对临夏人口发展的历史和现状进行分析研究,试图寻找解决人口问题的对策。