针对科研合作网络演化建模的基于Agent实验平台原型

科研合作网络是近年来复杂网络研究的热点问题之一,但当前关于科研合作网络动态演化问题的研究还很不充分,特别是把网络演化和网络中知识创造与传播问题结合起来的研究还鲜见报道.本文在分析Guimera等人提出的一个基于团队组合的科研合作网络演化模型的基础上,提出一个综合网络演化和网络中知识传播的动态网络建模框架暨元模型.进而,以所提出的元模型为依托,开发了一个计算机仿真实验平台原型,以辅助采用基于Agent建模范式的科研合作网络演化和知识传播研究.通过若干建模试验,初步验证了所提出的元模型和相应的实验平台原型的有效性.     

Optimal flight technique for V-style ski jumping

This paper describes the results of a numerical study to determine the optimal flight technique for V-style ski jumping. We attempt to answer the question of how a jumper should fly in order to increase their flight distance in a V-style posture. The index of performance in this optimization study is the horizontal flight distance, which is mathematically equivalent to the total flight distance, and the control parameters are the ski-operning angle and the angle of forward lean that the jumper employs (the body-ski angle). The flight trajectory is simulated on the basis of an aerodynamic database constructed from wind tunnel test data. It is found that the ski-opening angle should be increased in the first half of the flight, and then maintained at a constant value during the rest of the jump. Optimal control of the ski-opening angle when there is either a headwind or tailwind is also discussed. It is found that the jumper needs to control the skiopening angle over a wider range in the case of a headwind than in the case of a tailwind. The jumper's skill in controlling the ski-opening angle is very important for increasing the flight distance, especially in the case of a tailwind.     

基于概念相关性度量的语义Web服务匹配：模型及匹配器原型

针对当前主流语义Web服务匹配方法过分强调服务请求与服务广告的精确匹配从而导致用户在实际中难以获得真正所需要的Web服务、或在服务自动发现与集成任务中计算负荷过大的问题,本文把基于本体的概念语义相关性度量模型引入Web服务匹配,提出一个新的更"轻便"的语义Web服务匹配模型.该模型使用一系列概念组分别描述服务的服务类别、输入、输出、前提、效果等诸方面的语义信息,在此基础上通过基于本体的概念组之间的相关性度量模型分别评价服务请求与服务描述在这些方面的语义匹配度.总体语义匹配度被定义为输入、输出、前提、效果方面的语义匹配度的加权和.基于这一匹配模型,本文进而研究了相应的服务匹配器原型.初步的数据试验表明,本文所提模型能较好地适应用户需求表述的模糊性,从而提高服务匹配的召回率;从计算复杂性看,本文所提模型也优于基于严格逻辑推理的语义Web服务匹配模型.     

Teachers’ Autonomy in Today's Educational Climate: Current Perceptions From an Acceptable Instrument

This research evaluated the psychometric properties of Friedman's (1999) Teacher Work-Autonomy Scale (TWA) to determine whether it was an acceptable instrument to measure U.S. teacher autonomy in the present educational context. A second purpose was to ascertain the current status of teachers’ perceptions of their autonomy from a sample of U.S. teachers. Four hundred seventy-seven teachers from three public schools in Michigan participated in this study for a response rate of 30%. Factor analysis confirmed the multifaceted nature of teacher autonomy; however, somewhat different factor structures were found for the elementary and secondary teachers in this study, in comparison to that of Friedman. The TWA, without major modifications, appeared to be a valid and reliable instrument for use with a U.S. secondary sample but with limitation with an elementary sample. Elementary and secondary teachers perceived autonomy in the different factors in identical order, but with significant differences between their scores. Differences in school structure and conceptions of autonomy may have contributed to grade-level discrepancies. The findings suggest that administrators may be able to enhance teacher autonomy by releasing some of their power to include teachers in school leadership, specifically in the two areas teachers perceived with lowest autonomy: school finances and professional development.