流动儿童的教育绩效及其影响因素:多层线性模型分析

文章根据2006年11月在北京市某区进行的"流动儿童教育问题跟踪调查"数据,利用多层线性模型,探索性分析影响本地儿童、公立流动儿童、以及流动儿童在学业成绩上差异的主要因素;并讨论流动儿童教育公平问题.结果表明,三类儿童在学业成绩上存在着显著的差异;尽管影响儿童学业成绩的主要原因在于儿童自身的各种特征及其家庭背景,特别是其家庭社会经济地位;但是学校特征如学校平均SES和班级规模等将通过儿童自身及家庭的特征,间接地影响到学生的学业成绩,并改变儿童特征对于学业成绩的作用强度.这意味着教育资源在学校之间的不均匀分配也会成为社会不平等的一种生产机制.     

论李清照《词论》的女性主义话语立场

“话语立场”即出场言说的角度和取向。女性意识是李清照《词论》话语立场的基点 ,《词论》是词体建构发展至该阶段的对词体内部音乐性和文学性这一矛盾的一种共时性把握 ,其词体本质论的思想基础也正是女性意识。今人对《词论》话语立场两种截然相反的阐释取向出自相同的阐释策略 ,均未能切中肯綮以至于南辕北辙。阐释视角的转换是为了拓展阐释的空间 ,将被取代和遮蔽的言说声音还原于历史主义的阐释链条     

多元文化背景下大学生文化自觉缺失现状及影响因素分析

以高度的文化自觉和文化自信推进社会主义文化大发展大繁荣是中国特色社会主义建设的重要战略任务。而多元文化背景下大学生文化自觉问题已经成为关乎中国未来文化安全、关乎中国人才成长、关乎中华民族伟大复兴和世界和谐发展的重大问题。当前大学生文化自觉的现状不容乐观,存在诸多值得关注的问题。影响大学生文化自觉的因素很多,既有外源性的客观因素,也有内源性的主观因素。客观分析当前大学生文化自觉缺失现状及其主、客观影响因素,是深入研究大学生文化自觉培养问题的重要前提。     

生命伦理问题的国际软法规制

科技无国界,生命科技发展及其医学应用引发的诸多伦理难题跨越国界,日渐成为全球性的问题,亟待世界各国共同应对。以联合国教科文组织为代表的一些国际组织在过去的三十年来采用"宣言"(软法)而不是"条约"(硬法)的方式对生命伦理问题有所规制,创制了解决生命伦理问题的诸多国际软法。我国应重视生命科技国际软法规制之形成,发挥应有的主动权和话语权,积极成为国际社会的引领者。     

Retrospective change detection in categorical time series

The aim of this paper is to propose methods of detecting change in the coefficients of a multinomial logistic regression model for categorical time series offline. The alternatives to the null hypothesis of stationarity can be either the hypothesis that it is not true, or that there is a temporary change in the sequence. We use the efficient score vector of the partial likelihood function. This has several advantages. First, the alternative value of the parameter does not have to be estimated; hence, we have a procedure that has a simple structure with only one parameter estimation using all available observations. This is in contrast with the generalized likelihood ratio-based change point tests. The efficient score vector is used in various ways. As a vector, its components correspond to the different components of the multinomial logistic regression model’s parameter vector. Using its quadratic form a test can be defined, where the presence of a change in any or all parameters is tested for. If there are too many parameters one can test for any subset while treating the rest as nuisance parameters. Our motivating example is a DNA sequence of four categories, and our test result shows that in the published data the distribution of the four categories is not stationary.     

社会网络分析视角下复杂网络结构关系的综合测度

为了克服复杂网络节点数量繁多、结构关系不易测度的难题,文章提出一种社会网络分析视角下“以点界面”的研究思路.通过构建一个新的综合测度指标,完成对网络中节点的综合评价,实现对网络结构关系的测度.与现有社会网络单一测度指标相比,综合测度指标突破现有单一测度指标的局限,构建过程充分利用单一测度指标间关系规律.复杂网络仿真实验进一步表明,无论有中心结构的网络结构和无中心结构的网络结构,综合测度指标提高网络节点不同评价维度和网络角色自带信息的利用率,对网络中节点的全面刻画更为贴切,为复杂网络结构关系综合测度研究提供一种新工具,为提高生活生产效率、预防灾害负面影响提供参考和依据.     

A Note on High-Dimensional Linear Regression With Interactions

The problem of interaction selection in high-dimensional data analysis has recently received much attention. This note aims to address and clarify several fundamental issues in interaction selection for linear regression models, especially when the input dimension p is much larger than the sample size n. We first discuss how to give a formal definition of “importance” for main and interaction effects. Then we focus on two-stage methods, which are computationally attractive for high-dimensional data analysis but thus far have been regarded as heuristic. We revisit the counterexample of Turlach and provide new insight to justify two-stage methods from the theoretical perspective. In the end, we suggest new strategies for interaction selection under the marginality principle and provide some simulation results.     

失地农民健康生活方式测度及其影响因素研究

城镇化在改变了失地农民经济行为的同时,也将导致其生活方式的乡城变迁,其中面向城镇环境的健康生活方式转型对失地农民维系健康水平至关重要.本文从理论层面研究了城镇化背景下失地农民的健康生活方式转型机制及其影响因素;在此基础上,采用规范的健康促进生活方式量表(HPLP)对江苏泰州331个失地农民健康生活方式水平进行实证测度.结果表明,样本地区失地农民健康生活方式总体处于一般状况,其中运动锻炼水平显著不足.进一步运用分位数模型研究发现,相比而言,女性、文化程度较高以及患慢性病的失地农民群体更重视自我健康生活方式的塑造和提升,此外,征地满意度、医疗保险参与率和安置区公共健康服务等外部因素对促进失地农民健康生活方式发展也发挥了积极作用.     

Cloud manufacturing system for sheet metal processing

Abstract

Cloud computing is changing the way industries and enterprises run their businesses. Cloud manufacturing is emerging as an approach to transform the traditional manufacturing business model, while helping the manufacturer to align production efficiency with its business strategy, and creating intelligent factory networks that enable collaboration across the whole enterprise. Many production planning and control (PPC) problems are essentially optimisation problems, where the objective is to develop a plan that meets the demand at minimum cost or maximum profit. Because the underlying optimisation problem will vary in the different business and operation phases, it is important to think about optimisation in a dynamic mechanism and in a number of interlinked sub-problems at the same time. Cloud manufacturing has the potential to offer decision support as a service and medium of communication in PPC. To solve these problems and produce collaboration across the supply chain, this paper provides an overview of the state of the art in cloud manufacturing and presents a model of cloud-based production planning and production system for sheet metal processing.     

A lower bound for the adaptive two-echelon capacitated vehicle routing problem

Adaptive two-echelon capacitated vehicle routing problem (A2E-CVRP) proposed in this paper is a variant of the classical 2E-CVRP. Comparing to 2E-CVRP, A2E-CVRP has multiple depots and allows the vehicles to serve customers directly from the depots. Hence, it has more efficient solution and adapt to real-world environment. This paper gives a mathematical formulation for A2E-CVRP and derives a lower bound for it. The lower bound is used for deriving an upper bound subsequently, which is also an approximate solution of A2E-CVRP. Computational results on benchmark instances show that the A2E-CVRP outperforms the classical 2E-CVRP in the costs of routes.