The probabilistic tolerance design for a subsystem using taguchi's quadratic loss function

Taguchi (1984,1987) has derived tolerances for subsystems, subcomponents, parts and materials. However, he assumed that the relationship between a higher rank and a lower rank quality characteristic is deterministic. The basic structure of the above tolerance design problem is very similar to that of the screening problem. Tang (1987) proposed three cost models and derived an economic design for the screening problem of “the-bigger-the-better” quality characteristic in which the optimal specification limit ( or tolerance ) for a screening variable ( or a lower rank quality characteristic ) was obtained by minimizing the expected total cost function.Tang considered that the quality cost incurred only when the quality characteristic is out of specification while Taguchi considered that the quality cost incurred whenever the quality characteristic deviates from its nominal value. In this paper, a probabilistic relationship, namely, a bivariate normal distribution between the above two qualy characteristics as in a screening problem as well as Taguchi's quadratic loss function are considered together to develop a closed form solution of the tolerance design for a subsystem.     

Weighted re‐randomization tests for minimization with unbalanced allocation

Re‐randomization test has been considered as a robust alternative to the traditional population model‐based methods for analyzing randomized clinical trials. This is especially so when the clinical trials are randomized according to minimization, which is a popular covariate‐adaptive randomization method for ensuring balance among prognostic factors. Among various re‐randomization tests, fixed‐entry‐order re‐randomization is advocated as an effective strategy when a temporal trend is suspected. Yet when the minimization is applied to trials with unequal allocation, fixed‐entry‐order re‐randomization test is biased and thus compromised in power. We find that the bias is due to non‐uniform re‐allocation probabilities incurred by the re‐randomization in this case. We therefore propose a weighted fixed‐entry‐order re‐randomization test to overcome the bias. The performance of the new test was investigated in simulation studies that mimic the settings of a real clinical trial. The weighted re‐randomization test was found to work well in the scenarios investigated including the presence of a strong temporal trend. Copyright © 2013 John Wiley & Sons, Ltd.     

Piecewise deterministic Markov processes applied to fatigue crack growth modelling

In this paper, we use a particular piecewise deterministic Markov process (PDMP) to model the evolution of a degradation mechanism that may arise in various structural components, namely, the fatigue crack growth. We first derive some probability results on the stochastic dynamics with the help of Markov renewal theory: a closed-form solution for the transition function of the PDMP is given. Then, we investigate some methods to estimate the parameters of the dynamical system, involving Bogolyubov's averaging principle and maximum likelihood estimation for the infinitesimal generator of the underlying jump Markov process. Numerical applications on a real crack data set are given.     

民族问题研究的基本思路和重要课题

本文从民族问题的研究对象、民族问题研究的基本思路、重要课题和国家需要承担的责任等四个方面,对我国民族问题研究进行了系统的论述,提出了重要的观点.     

中国人口年龄结构特征与变化趋势分析--基于1995～2014年数据的实证研究

人口年龄结构是经过多年人口自然增长和迁移变动等综合作用而形成的客观状况,对未来人口发展的速度和趋势以及国家或地区经济社会整体发展产生重要影响。本文通过对1995～2014年数据的实证分析,发现20年来我国人口年龄结构呈现以下特征：少儿人口数量减少且比重呈持续下降趋势;劳动年龄人口数量稳步增长且比重呈稳定上升趋势;老年人口数量持续增长且比重呈上升趋势,老龄化进程加快。总体人口年龄结构呈现老年型,各地区人口老龄化程度存在差异。各地人口负担系数存在较大差异,人均GDP与总抚养比和少年儿童抚养比呈负相关,与老年人口抚养比呈正相关。经济发达省市区人口负担系数较小;城乡人口比例呈持续升高态势;城乡人口总抚养比和少儿抚养比呈下降趋势,城乡老年人口抚养比呈稳步升高态势;乡村人口抚养比高于城镇。     

高职院校数字图书馆建设存在的问题及对策

数字图书馆建设已成为21世纪图书馆发展的主要方向。针对我国数字图书馆建设中存在的问题进行分析,提出了相应对策。     

ADF模式中漂移项和趋势项检验量分布与Bootstrap检验研究

在推导ADF检验模式下趋势项和漂移项伪t检验量极限分布基础上,提出修正的系数检验量。研究表明,它们与DF检验模式下检验量具有相同的极限分布;构造漂移项和趋势项检验的Bootstrap实现方法并证明了有效性。将蒙特卡洛模拟技术与临界值检验方法进行对比,结果表明Bootstrap方法能够明显降低检验的水平扭曲,在检验功效方面也有一定优势。模拟也显示临界值检验的局限性和Bootstrap方法的稳健性。     

山东省百年人口老龄化趋势前瞻

山东省是我国的人口大省,也是人口老龄化速度较快的省份。本文利用人口发展数学模型,得出五种预测方案,然后再根据山东省的实际形势确定了备选方案,分析了山东省百年人口老龄化总趋势,以及2005-2020年山东省人口老龄化发展特征,最后提出了相应的对策和建议。     

刍议信息时代企业组织形态的演进与趋势结构

生产力发展、资本集中、市场竞争等,使发挥激励功能、资源优化配置功能、利益合理分配功能的企业不断演化.虚拟企业是企业未来组织形式的发展趋向,这种趋向决定了信息时代企业组织结构是"寡头主导,大、中、小共生"的竞争动态演进型组织状态.     

民族主义视域中的左翼文学思潮探析

政治/阶级斗争的研究视角对于认识左翼文学思潮有很大的不适切性。从民族主义诉求的角度来观照左翼文学思潮,会发现左翼文学所蕴含的民族解放与再造的宏大主题。民族主义诉求与左翼文学思潮是以"共体"形式存在的,以往的研究者有意无意地忽视了从民族主义走进左翼文学思潮这条思维路径。