A hierarchy of lorenz curves based on the generalized tukey's lambda distribution

A hierarchy of Lorenz curves based on the generalized Tukey's Lambda distribution is proposed. Representations of the corresponding distribution and density function are also provided, together with popular inequality measures. Estimation methods are suggested. Finally, a comparison with other parametric families of Lorenz curves is established.     

Improved attribute acceptance sampling plans based on maxima nomination sampling

This paper demonstrates the use of maxima nomination sampling (MNS) technique in design and evaluation of single AQL, LTPD, and EQL acceptance sampling plans for attributes. We exploit the effect of sample size and acceptance number on the performance of our proposed MNS plans using operating characteristic (OC) curve. Among other results, we show that MNS acceptance sampling plans with smaller sample size and bigger acceptance number perform better than commonly used acceptance sampling plans for attributes based on simple random sampling (SRS) technique. Indeed, MNS acceptance sampling plans result in OC curves which, compared to their SRS counterparts, are much closer to the ideal OC curve. A computer program is designed which can be used to specify the optimum MNS acceptance sampling plan and to show, visually, how the shape of the OC curve changes when parameters of the acceptance sampling plan vary. Theoretical results and numerical evaluations are given.     

Using relative utility curves to evaluate risk prediction

Summary.  Because many medical decisions are based on risk prediction models that are constructed from medical history and results of tests, the evaluation of these prediction models is important. This paper makes five contributions to this evaluation: the relative utility curve which gauges the potential for better prediction in terms of utilities, without the need for a reference level for one utility, while providing a sensitivity analysis for misspecification of utilities, the relevant region, which is the set of values of prediction performance that are consistent with the recommended treatment status in the absence of prediction, the test threshold, which is the minimum number of tests that would be traded for a true positive prediction in order for the expected utility to be non-negative, the evaluation of two-stage predictions that reduce test costs and connections between various measures of performance of prediction. An application involving the risk of cardiovascular disease is discussed.     

Parental Work Schedules and Children's Cognitive Trajectories

Previous work has shown an association between mothers' nonstandard work schedules and children's well-being. We built on this research by examining the relationship between parental shift work and children's reading and math trajectories from age 5/6 to 13/14. Using data (N=7,105) from the National Longitudinal Survey of Youth and growth curve modeling, we found that children's math and reading trajectories were related to parents' type of nonstandard shifts (i.e., evening, night, or variable). We found that having a mother who worked more years at a night shift was associated with lower reading scores, having a mother work more years at evening or night shifts was associated with reduced math trajectories, and having a father work more years at an evening shift was associated with reduced math scores. Mediation tests suggest that eating meals together, parental knowledge about children's whereabouts, and certain after-school activities might help explain these results.     

论劳动力胀供给膨对宏观经济运行的不良影响

劳动力供给膨胀问题是一个严重的社会问题,劳动力供给膨胀对宏观经济的运行产生许多不良影响,集中体现在市场经济效率、社会财富分配、社会稳定三个方面。研究劳动力供给膨胀对一个国家构建和谐社会具有重要的理论意义和现实意义。     

中国电力工业环境学习曲线与节能减排潜力分析

电力行业在生产过程中,消耗大量的资源且排放大量的污染物,在资源环境保护方面承担着非常重要的责任。利用1991—2005年的时间序列数据,选取万元产值能耗、水耗、SO2排放、COD排放等九个主要指标,建立电力工业能耗和大气污染、水耗和水环境污染随着人均GDP变化的环境学习曲线,并根据这些曲线分析了不同时段,我国电力工业的环境负荷和节能减排潜力。结果发现:我国电力工业资源环境九项指标均随人均GDP的增长呈幂指数衰减,不同时段电力工业万元产值环境负荷逐渐下降,同时节能减排的潜力也逐年下降,这是由环保意识增强和经济技术发展而产生的必然结果。     

Computing Optimal Beams in Two and Three Dimensions

The problem of computing an optimal beam among weighted regions (called the optimal beam problem) arises in several applied areas such as radiation therapy, stereotactic brain surgery, medical surgery, geological exploration, manufacturing, and environmental engineering. In this paper, we present computational geometry techniques that enable us to develop efficient algorithms for solving various optimal beam problems among weighted regions in two and three dimensional spaces. In particular, we consider two types of problems: the covering problems (seeking an optimal beam to contain a specified target region), and the piercing problems (seeking an optimal beam of a fixed shape to pierce the target region). We investigate several versions of these problems, with a variety of beam shapes and target region shapes in 2-D and 3-D. Our algorithms are based on interesting combinations of computational geometry techniques and optimization methods, and transform the optimal beam problems to solving a collection of instances of certain special non-linear optimization problems. Our approach makes use of interesting geometric observations, such as utilizing some new features of Minkowski sums.     

对称性在定积分中的应用

对称性在定积分中的应用孙军安，郑德印利用函数图形的对称性可简化定积分的计算。在特殊情况下，甚至可以求出原函数不是初等函数的定积分。因此掌握用对称性计算定积分的方法是必要的有益的。本文首先给出一个引理，由此得出一系列有趣的结果，并通过实例说明这些结果的...     

对我校研究生入学考试数学成绩的分析

本文利用统计的方法,使用灰色关联度对某一年的研究生入学数学成绩进行了统计分析,找出了影响考生成绩的主要因子,为我校如何改进数学教学方法及考生如何准备研究生数学入学考试提出了一些建议。     

基于圆弧样条的复杂零件型面数控测量数据拟合

讨论了数控测量数据的一般处理方法及复杂零件型面多测量点数据对数控加工的影响．研究了利用圆弧样条拟合测量数据和生成加工刀位轨迹的方法．