空间光通信ATP系统设计分析

空间光束捕获、跟踪、瞄准（ＡＴＰ）技术在空间光通信中具有重要地位。文中讨论了空间光通信系统中的ＡＴＰ伺服系统的结构,并对系统稳态设计和系统动态综合等关键问题进行了详细的分析和研究。     

考虑脉冲现象的复杂供应链系统及其稳定策略

供应链系统是一个复杂的系统,一方面由于时间延迟、信息不对称及反馈机制等,会产生牛鞭效应,另一方面供应链具有需求突增或骤减的脉冲特点,上述现象都可能导致供应链系统混沌,而现有的供应链模型仅考虑了“牛鞭效应”,并未考虑脉冲现象对供应链系统的影响。文章建立了考虑脉冲现象的供应链模型,分析了脉冲现象对供应链系统的影响,并给出了使供应链系统稳定的策略,讨论了参数扰动对该模型的影响,通过数值算例验证了稳定策略的有效性。研究发现:脉冲现象对供应链系统有着显著影响,但只要选取恰当的脉冲强度和脉冲时间间隔,供应链系统是可以稳定的。     

英语习语的变体剖析

从英语习语的变体类型及修辞特色两方面剖析了英语习语变体这一特殊语言现象,归纳总结了临时变体的常见形式,并从交际修辞和美学修辞的角度分析了习语变体的修辞特色和功能。     

西部六城市流动人口调查综合报告

自中央实施"西部大开发"发展战略以来,在西部省区基础设施和许多行业的大量投资吸引了大量来自东部和邻近农村的流动人员。我国西部是少数族群聚居区,在发展过程中各民族之间存在相互协作的广阔空间,也存在发展机会和利益分配方面的相互竞争关系。为了调查和分析近年来西部的人口流动及其对当地族群关系的影响,我们在西部六个重要城市开展了流动人口的问卷调查。本文以这次问卷调查的数据为基础,系统地分析了西部大城市中流动人口的基本特征、就业状况、收入与消费情况以及他们与当地居民之间的交往。这些量化分析的研究成果,将便于我们进一步深入分析"西部大开发"过程中人口流动对当地经济建设、社会生活和族际交往所带来的影响。     

The effect of paid maternity leave on low-income families' welfare use in the US

Despite the critical role that paid maternity leave can assume in the economic lives of low-income families, research to date has paid insufficient attention to whether paid maternity leave reduces welfare use for low-income families. Using the Current Population Survey (CPS) March Supplement 2007–2014 with the difference-in-difference (DiD) technique, this study finds a significant policy effect of paid maternity leave on reducing the probability of using Temporary Assistance for Needy Families (TANF), TANF benefit amounts and TANF participation length. This study confirms that paid maternity leave is likely to prevent low-income families from using welfare during job interruptions stemming from the birth of a child. Given that TANF is often associated with negative political and social connotations, paid maternity leave can be used as an important social policy to improve economic security as well as offer empowerment in overall social standing for low-income mothers. The discussion focuses on the implications of the findings in a broader context of American welfare states.     

论外出农民工“临时夫妻”的性质及其解决对策

目前我国沿海城市出现了外出农民工“临时夫妻”现象,且呈现愈演愈烈的趋势。尽管问题的产生有其特殊背景和原因,但这种行为在性质上是违反社会公序良俗和法律的,容易引发家庭纠纷和社会矛盾。在推进新型城镇化的进程中,我们应当通过制定《农民工权益保障法》,破除城乡一体化障碍,促进农村人口流动模式的转变,加强法制宣传教育,依法处理矛盾纠纷,惩治破坏婚姻家庭秩序的违法犯罪行为等多种途径,从法律上切实维护外出农民工的婚姻家庭权益,为实现外出农民工市民化提供法治保障。     

我们的四个误区及其反思--对当前我国维护社会稳定工作的社会学思考

维护社会稳定是社会经济发展的基本前提,然而,在我国维护社会稳定的实际操作过程中,还存在着一些长期遗留的误区.其主要是第一,过于强调社会要素的稳定,忽视了社会结构的稳定;第二,过于强调资源配置的集中,忽视了社会分化的影响;第三,过于强调社会冲突的负功能,忽视了对手段性冲突的引导;第四,过于强调政府在社会控制中的作用,忽视了中介组织的调节.     

Risk-Informed Requirements for Design and Assessment of Structures Under Temporary Use

The relatively high failure rates, with important consequences in many cases, suggest that the implicitly acceptable risk levels corresponding to temporary civil engineering structures and activities might exceed the bounds of normally acceptable levels associated with different societal activities. Among other reasons, this may be attributed to the lack of a rational approach for the assessment of risks associated with the different technologies supporting these activities in general, and for structures in particular. There is a need for establishing appropriate target reliability levels for structures under temporary use taking into account specific circumstances such as reduced risk exposure times. This issue is being addressed in this article. Acceptance criteria for building-structure-related risks to persons obtained in prior studies are adapted to the special circumstances of nonpermanent risk exposure. Thereby, the general principle followed is to maintain the same risk levels per time unit as for permanently occupied buildings. The adaptation is based on the statistical annual fatality rate, a life safety risk metric that allows for a consistent comparison of risks across different societal activities and technologies. It is shown that the target reliability indices taking account of the temporary use of buildings might be significantly higher than the values suggested for permanently used structures.     

Postdisaster Housing Stages: A Markov Chain Approach to Model Sequences and Duration Based on Social Vulnerability

Housing recovery is an unequal and complex process presumed to occur in four stages: emergency shelter, temporary shelter, temporary housing, and permanent housing. This work questions the four-stage typology and examines how different types of shelter align with multiple housing recovery stages given different levels of social vulnerability. This article also presents a Markov chain model of the postdisaster housing recovery process that focuses on the experience of the household. The model predicts the sequence and timing of a household going through housing recovery, capturing households that end in either permanent housing or a fifth possible stage of failure. The probability of a household transitioning through the stages is computed using a transition probability matrix (TPM). The TPM is assembled using proposed transition probability models that vary with the social vulnerability of the household. Monte Carlo techniques are applied to demonstrate the range of sequences and timing that households experience going through the housing recovery process. A set of computational rules are established for sending a household to the fifth stage, representing a household languishing in unstable housing. This predictive model is exemplified on a virtual community, Centerville, where following a severe earthquake scenario, differences in housing recovery times exceed four years. The Centerville analysis results in nearly 5% of households languishing in unstable housing, thereby failing to reach housing recovery. These findings highlight the disparate trajectories experienced by households with different levels of social vulnerability. Recommendations are provided at the end for more equitable postdisaster recovery policies.     

凌纯声先生的赫哲族田野调查--从现代中国实地调查研究的学术背景谈起

凌纯声先生1930年的赫哲族田野调查是中国民族学和人类学界一次科学的实地调查,具有开创性意义.本文从现代中国提倡和注重实地调查研究的学术背景来审视这次田野调查.上世纪20年代后,中国人文社会科学逐渐从吸收传播"西学"向研究中国历史、社会、民族文化转变,朝着"本土化"的方向努力,从而形成了提倡实地调查研究的学术风气,而且中国学者进行了多次学术实践.这次田野调查与那个时代的学术背景密切相关,并且体现出其学术背景.本文还论述了蔡元培先生与这次田野调查的密切关系.