C2C卖家的诚信行为模式及其动态性研究

现有电子商务的信用评价体系单一维度的特点使得评级体系难以准确衡量、比较店铺在各维度之间的差异及其变化。为了提高C2C电子商务信用评级体系的信息揭示作用,本文试图从多维度指标分析店铺的诚信行为模式及其动态性。本文对淘宝7大行业不同信用等级的卖家的诚信指标数据进行聚类分析表明,店铺在动态评分、信用等级、好评率上分别具有六类不同的静态组合特征,信用积分在解释店铺诚信状态上弱于动态评分和好评率指标。动态模式分析表明,店铺的好评率、动态评分指标及其与同业行业比值会呈现出三个不同的组合变化趋势。最后本文提出对现有的评价体系改进,以体现店铺之间在模式上的差异,从而真实展现卖家的诚信水平。     

气体钻与泥浆钻全井段钻柱动力学对比研究

全井段钻柱在井内运动过程是一个非常复杂的非线性动力学问题，不可能得到比较完美的解析解，如果采用室内试验或者现场试验研究，其成本又会很高且很难实现。因此，在弹塑性力学、岩石力学和钻柱力学的基础上，以四川某井基本钻井参数和钻具组合为依据，采用有限元法建立了塔式钻具钻至1486m井深时的全井段三维钻柱模型和相应的井筒模型，并且建立了钻头与岩石以及钻柱与井筒之间的随时间变化且有摩擦系数的接触关系和相对应的泥浆钻井模型，对比分析了钻柱在动态钻进过程中的井口参数、钻头上压力和转动速度以及全井段钻柱的弯矩扭矩变化等结果，得出气体钻井与泥浆钻井全井段钻柱的运动规律以及钻铤失效机理的差异。为认识气体钻井全井段钻柱的运动规律提供了新的研究方法，对气体钻井中钻柱力学、井斜控制和设备等方面的研究都有较好的现实意义。     

Urban “slums” and social mobility

Informal urban settlements determine the wellbeing of a large section of global humanity. Yet there has been little research on their role in facilitating social mobility. In theory such settlements may foster human progress by linking rural–urban migrants to the services, contacts and livelihoods concentrated in cities. The article uses longitudinal data for South Africa to explore the magnitude of social progression among people living within informal settlements compared with rural areas and formal urban areas. It finds that there may be some advantage from living in an informal settlement compared with a rural area, but the effect is not strong. The impact may be larger in the more prosperous Gauteng city‐region than in other urban regions.     

RESEARCH NOTE Some evidence against the assumption that approval of family planning is associated with frequency of spouses' discussion of the subject

Much previous work on the relationship between respondent's reported frequency of discussion with spouse about family planning and correctness of reporting spouse's approval of family planning has led to the conclusion that discussion promotes approval. In this paper, data from the 1998 Kenya Demographic and Health Surveys are used to show that a focus on the relationship between frequency of discussion and correctness of reporting partner's disapproval of family planning leads to sceptical conclusions about the effects of discussion in improving knowledge of partner's attitude or in promoting approval.     

Terrorist Population Dynamics Model

A system that includes a number of terrorist cells is considered. The cells can consist of one or more terrorists. The current number of terrorist cells is further denoted by N(t), where t is a current time counted from any appropriate origin. The objective is to find the evolution of the system in terms of N(t) and some interpretable parameters, such as the initial number of the terrorist cells N0=N(0), the cell disabling rate constant lambda (or the cell half-life t1/2), and the rate of formation of new cells P. The cost-effectiveness analysis, performed in the framework of the model, reveals that the effectiveness of disabling a terrorist cell is getting worse after 2-3 half-lives of a cell, which shows that if the anti-terrorist actions have not reached their goal during that time, the respective policy should be considered for revision, using the risk assessment consideration. Another important issue raised concerns balancing the efforts related to counterterrorism actions inside the system and the efforts protecting its borders. The respective data analysis is suggested and illustrated using simulated data.     

An individual-based model for competingDrosophila populations

An individual-based model forDrosophila is formulated, based on competition amongst larvae consuming the same batch of food. The predictions of the model are supported by data for single speciesDrosophila populations reared in the laboratory. The model is used to build a simple discrete model for the dynamics ofDrosophila populations that are kept over a number of generations. The dynamics of a single species is shown to give either a stable equilibrium or fluctuations which can be periodic or chaotic. When the dynamics of a species in the absence of the other is periodic or chaotic, we found coexistence or two alternative states, on neither of which the species can coexist.     

组织内派系形成的网络动态分析

本文以行动者的模拟模型考察公司中的雇员形成派系的过程。基于互惠原则与资源交换理论，模型展示了互助行为使人与人之间产生连带，逐渐形成在内部相互支持的群体，这种群体进一步排除他人的参与，并最终在组织中形成了派系。在考察影响派系形成的因素时，本文选取了与工作环境相关的两个变量以及表达组织气氛的一个变量。曲线图展示了本文的实验结果：接近或超过个人极限资源量的工作量和越不平均的工作量分配状况越有可能提高派系形成的速度和数量，并可能导致派系的不断分裂；而太小的工作量与过于均等的工作分配可使个体交往倾向减弱而处于相对孤立状态。
     

流体力学多媒体教学的探讨

针对流体力学课程理论性强,课程实验多,实验受条件限制大的特点,并结合多年的教学实践经验,制作了多媒体课件,在理论和实践的教学效果上作了有益的探索和研究。     

超临界流体萃取装置使用指南

超临界流体萃取(SFE)是近年来兴起的一种新的分离技术,本文简述了超临界萃取装置的工作原理及操作方法,并对研究人员如何正确使用超临界萃取装置提出了一些注意事项,希望对研究人员使用超临界萃取装置提供一些帮助。     

Little naked pangs of the self: the real performance of the self and the function of trust in Goffman's action theory

The aim of this article is to discuss some of the leading features of Erving Goffman's action theory as an alternative to the ‘orthodox’ paradigms of sociology, viewed as a structuralist and functionalist science that defines social constructs by their shared rules and values, and as a drifting of action, in the sense of intention, toward an individualistic version. The author examines Goffman's shift of the focus of attention from the boundaries of a social sense of action to the social dialectic of ‘defining a situation’ (W. Thomas) as conducted by the social actors in a renewal of Simmel's ‘empowering covenants’ (wechselwirkung) in the multiple casual social connections that make up the ‘social buzz’ in a society. The author moreover discusses Goffman's action as a kind of playacting regulating cognitive and expressive face-to-face ‘traffic’ between the social actors. This relational dynamic creates an interactive play based on encounters – in which one's opening to another is fraught with risks of deception – regulated by trust as a central resource for social interactions. Trust, in its interpersonal and systemic variants, constitutes a universal social datum and an elementary precondition for social exchanges and the cooperation between individuals. Trust, thus, functions as comparer between reciprocal expectations and a regulator of freedom tending to the stability of the social system.