重庆轻轨二号线运营不安全因素分析及对策

城市轨道交通近年来在我国得到了快速发展,其运营安全对城市的经济活动和市民的日常生活有举足轻重的影响。介绍重庆轻轨二号线的基本情况,从安全运营的角度分析运营中存在的问题,并据此提出相应的解决对策。     

What are friends for? Elective communities of single people

The paper presents the results of a qualitative research on friendship networks of single people. The research has been undertaken using social network analysis tools (egonetworks) and qualitative interviews, on a non-representative sample of 23 heterosexual singles of Milan, aged between 25 and 35 years, 12 male and 11 female.     

基于成员合作的组织有效性建模分析

从组织成员合作出发,通过建立博弈模型研究成员目标优化问题,建立线性规划模型研究组织目标优化问题,并把个人目标优化条件下成员投入的人力资源作为组织目标优化的资源约束,以此建立博弈分析和线性规划的联系,使个人目标优化和组织目标优化结合起来,并在此基础上形成基于成员合作的组织有效性分析模型。     

Survival Convergence and the Preceding Mortality Crossover for Two Population Subgroups

In this paper, we present and develop the argument that if the survival functions for two population subgroups converge in later life, a mortality crossover must precede the occurrence of this convergence. Specifically, two survival curves, S ₁(x) and S ₂(x), associated with two distinct population subgroups, G₁ and G₂, tend to converge before all members die out, as often observed and anticipated. This convergence leads to an increased mortality acceleration for the “advantaged” group, and eventually fosters the occurrence of a mortality crossover. We present a mathematical proof for this relationship and offer several explanations for the mechanisms involved in the process of survival convergence and the preceding mortality crossover. This new presentation demonstrates that mortality crossover is a highly observable demographic event given the trend of survival convergence in later life.     

A likelihood ratio test for bimodality in two-component mixtures with application to regional income distribution in the EU

We propose a parametric test for bimodality based on the likelihood principle by using two-component mixtures. The test uses explicit characterizations of the modal structure of such mixtures in terms of their parameters. Examples include the univariate and multivariate normal distributions and the von Mises distribution. We present the asymptotic distribution of the proposed test and analyze its finite sample performance in a simulation study. To illustrate our method, we use mixtures to investigate the modal structure of the cross-sectional distribution of per capita log GDP across EU regions from 1977 to 1993. Although these mixtures clearly have two components over the whole time period, the resulting distributions evolve from bimodality toward unimodality at the end of the 1970s.     

Improving the Efficiency of the Nelson–Aalen Estimator: the Naive Local Constant Estimator

Abstract.  The Nelson–Aalen estimator is well known to be an asymptotically efficient estimator of the cumulative hazard function, see Andersen et al. ( Statistical models based on counting processes , Springer-Verlag, New York, 1993) among many others. In this paper, we show that the efficiency of the Nelson–Aalen estimator can be considerably improved by using more information in the estimation process than the traditional Nelson–Aalen estimator uses. While our approach results in a biased estimator, the variance improvement is substantial. By optimizing the balance between the bias loss and the variance improvement, we obtain results on the efficiency gain. Several examples for known failure time distributions are used to illustrate these ideas.     

Factors influencing Soay sheep survival

We present a survival analysis of Soay sheep mark recapture and recovery data. Unlike previous conditional analyses, it is not necessary to assume equality of recovery and recapture probabilities; instead these are estimated by maximum likelihood. Male and female sheep are treated separately, with the higher numbers and survival probabilities of the females resulting in a more complex model than that used for the males. In both cases, however, age and time aspects need to be included and there is a strong indication of a reduction in survival for sheep aged 7 years or more. Time variation in survival is related to the size of the population and selected weather variables, by using logistic regression. The size of the population significantly affects the survival probabilities of male and female lambs, and of female sheep aged 7 or more years. March rainfall and a measure of the North Atlantic oscillation are found to influence survival significantly for all age groups considered, for both males and females. Either of these weather variables can be used in a model. Several phenotypic and genotypic individual covariates are also fitted. The only covariate which is found to influence survival significantly is the type of horn of first-year female sheep. There is a substantial variation in the recovery probabilities over time, reflecting in part the increased effort when a population crash was expected. The goodness of fit of the model is checked by using graphical procedures.     

综合阻尼系统的模态分析和时序模型

本文定义同时计及粘性阻尼和结构阻尼的系统为综合阻尼系统。讨论了多自由度比例综合阻尼系统的模态分析。推导出传递函数矩阵的表达式。应用拉氏变换和Z变换间关系,得到系统的ARMA时间序列模型。     

On Robust Analysis of a Normal Location Parameter

Pericchi and Smith considered a normal location parameter problem with double-exponential and Student t prior distributions. These two prior distributions both belong to the class of scale mixtures of normal distributions and are useful in providing a robust analysis of the normal location parameter problem. In this paper we extend the analysis to other scale mixtures of normal distributions, such as the exponential power and the symmetric stable distributions.     

A decision support system for the graph model of conflicts

A comprehensive decision support system called GMCA (Graph Model for Conflict Analysis) implementing the multi-player graph model for analyzing conflicts is developed. GMCA contains algorithms for the rapid computation of a wide range of solution concepts, thereby enabling decision makers to take account of the diversity of human behavior. Using an engineering case study, the key features of GMCA are illustrated.