长江流域城市人口分布及空间相关性研究

本文选取长江流域104个城市人口样本作为研究对象,采用人口分布的结构指数和空间自相关分析方法,以及借用GIS技术来研究长江流域城市人口分布的空间动态特征和城市人口之间的功能联系。结果表明,长江流域城市人口空间结构呈均衡发展态势;人口密度分布呈现趋同趋势;城市人口与邻近城市人口之间的空间正相关要多于空间负相关;长江流域城市人口之间的空间关联性被分为八种类型。     

地区间个人收入差距的状况及特点(英文)

在地区收入差距的文献中,一直缺乏从个人收入角度出发的研究;而关于个人收入分配的研究,也很少考察地区差异。文章使用2005年全国1％人口普查数据,从个人收入角度描述了全国及（几种不同定义下的）地区间的个人收入差距,并分析了影响个人收入差距的因素,得到了一些有意义的结果。     

Some characterizations of discrete distributions based on weak records

Let X ₁, X ₂,... be iid random variables (rv's) with the support on nonnegative integers and let (W _n , n≥0) denote the corresponding sequence of weak record values. We obtain new characterization of geometric and some other discrete distributions based on different forms of partial independence of rv's W _n and W _n+r —W _n for some fixed n≥0 and r≥1. We also prove that rv's W ₀ and W _n+1 —W _n have identical distribution if and only if (iff) the underlying distribution is geometric.     

BATHTUB-TYPE CURVES IN RELIABILITY AND BEYOND

Finding optimal, or at least good, maintenance and repair policies is crucial in reliability engineering. Likewise, describing life phases of human mortality is important when determining social policy or insurance premiums. In these tasks, one searches for distributions to fit data and then makes inferences about the population(s). In the present paper, we focus on bathtub‐type distributions and provide a view of certain problems, methods and solutions, and a few challenges, that can be encountered in reliability engineering, survival analysis, demography and actuarial science.     

利用稳定分布构建开放式基金业绩评价体系

经典的基金业绩评价方法是在收益率服从正态分布假设下构建风险指标，该指标或者高估风险，或者低估风险。可引入稳定分布来描述收益率，并利用稳定分布，构建风险调整的基金业绩评价体系，并利用该体系对我国开放式基金的业绩进行评价。     

集聚效应、集聚效率与城市规模分布变化

摘　　要:本文从城市集聚效应的视角,分析我国城市规模分布的结构性变化的机制,在此基础上构建了包含集聚效应的城市总量生产函数的计量经济学模型,然后应用OLS方法估算我国不同规模等级城市的平均集聚效应指数和平均集聚效率指数．并对比分析其对城市规模分布变化的影响。本文的实证结果表明,平均集聚效率指数的高低与城市规模分布比重的增减相一致。     

Easy-to-construct confidence bands for comparing two simple linear regression lines

This paper shows how to construct confidence bands for the difference between two simple linear regression lines. These confidence bands provide directly the information on the magnitude of the difference between the regression lines over an interval of interest and, as a by-product, can be used as a formal test of the difference between the two regression lines. Various different shapes of confidence bands are illustrated, and particular attention is paid towards confidence bands whose construction only involves critical points from standard distributions so that they are consequently easy to construct.     

Maximum log-likelihood ratio test for a change in three parameter Weibull distribution

Asymptotic behavior of a log-likelihood ratio statistic for testing a change in a three parameter Weibull distribution is studied. It is shown that if a shape parameter α>2$\alpha >2$ the law of iterated logarithm for maximum-likelihood estimators is still valid and the log-likelihood testing statistic is asymptotically distributed (after an appropriate normalization) according to a Gumbel distribution.     

Stochastic Modelling of Times to Temperature for Furnaces Supplying Titanium Blooms to a Rolling Mill at TIMET

In conjunction with TIMET at Waunarlwydd (Swansea, UK) a model has been developed that will optimise the scheduling of various blooms to their eight furnaces so as to minimise the time taken to roll these blooms into the finished mill products. This production scheduling model requires reliable data on times taken for the various furnaces that heat the slabs and blooms to reach the temperatures required for rolling. These times to temperature are stochastic in nature and this paper identifies the distributional form for these times using the generalised F distribution as a modelling framework. The times to temperature were found to be similarly distributed over all furnaces. The identified distributional forms were incorporated into the scheduling model to optimise a particular campaign that was run at TIMET Swansea. Amongst other conclusion it was found that, compared to the actual campaign, the model produced a schedule that reduced the makespan by some 35%.     

几种传输线的场分布

求开放平板线、外正三角形內圆同轴线、外方內圆同轴线、外正六边形內圆同轴线的特性阻抗而建立的精确保角变换的基础上,本文进一步讨论了显式逆变换函数,从而求得了这几种传输线的场分布的闭合表达式。由于所用保角变换的精确性,所得的显式场分布在内导体和外导体的内接圆尺寸之比小于0.5in。基本上是准确的,在这个尺寸比稍大些时也可作为参考。这些场分布对于了解传输线的功率容量,计算衰减常数,考虑功率耦合,设计有关的有源器件等都是必不可少的。文中获得的几种传输线的场分布的显著特点是计算方便,在一般实用范围內有足够的精度。