CFD技术在流体机械中的应用与发展

流体机械在轻工行业、化工行业等多种行业都得到广泛应用,通过分析CFD技术在流体机械的应用现状和发展 趋势,针对湍流模型的选择、网格的分类及使用、计算域和边界条件的确定、计算模型的验证等方面,指出了CFD技术计 算结果的可信度和二次开发应该引起重视。提出CFD技术发展方向应该是：既具有高适应、高速度、集成化和易用性的 特点,又有正确合理的V＆V评价体系。     

多层角联锁织机设计

针对一种基于PLC和触摸屏作控制系统的角联锁织物自动编织机,设计了多经轴送经装置、自动寻找梭口引纬 装置、夹板夹持织物卷取装置等,有效地消除了普通二维织机只能织造层数较少的角联锁织物的弊端。织机的控制系统 以PLC为核心,控制整机的运行状态;同时与触摸屏进行通信,将整机运行数据以动态图的形式显示,并接受触摸屏给 定的工艺参数来控制执行元件,实现了操作人员与自动编织机的“人机对话”功能。     

基于模糊层次分析法的沟域旅游资源评价

沟域旅游是乡村旅游的新模式,沟域旅游产品设计离不开沟域旅游资源评价。本研究选择模糊层次分析法(FAHP),试图构建沟域旅游资源评价的数学模型。采用专家赋分法确定指标体系,该体系包含4个指标18个因子。通过建立判断矩阵、一致性检验,计算出各指标的权重。以大梨树为例,计算出综合得分。结果证明FAHP方法在对沟域旅游资源进行评价时是可以通过的,并且简单易行。     

Community older adults’ attitude towards the use of assistive devices

This study investigates how older adults’ attitude patterns affect assistive devices’ (AD) use in a small-household context of Singapore. Community older adults with physical limitations (n = 481) completed face-to-face interviews for 90 min. Latent Profile Analysis analysed multiple indicators of attitudes towards ADs. Three groups were classified: positive attitude group (PAG); negative attitude group (NAG); and unwillingness to pay for ADs (UPG). PAG was most likely to use ADs, while UPG was least likely to use ADs. The findings are expected to help older adults age in place by improving equal distribution of technology resources that assist with daily tasks and activities.     

从泰始四年籍田礼看晋武帝的黄老思想

晋武帝于泰始四年举行亲耕籍田的仪式,推行了诸如务本俭用、约法省刑、因循任下等一系列具有清静无为特点的政治举措。这是晋武帝有意模仿汉文帝的黄老无为之治,为缓和前朝所遗留的政俗诸弊而采取的手段。这些举措确实起到充实西晋国力的作用,也为伐吴之役及统一天下奠定了基础。对这些政治现象进行分析,可以发现在司马氏标榜儒学名教之治的表面下,黄老思想实际上推动着晋初政治的进程,并对当时的政治文化产生了极为深刻的影响。     

非农业户籍会使人更幸福吗

中国的户籍制度相对比较特殊,它曾衍生了大量“农转非”等户口买卖现象,这使人不禁产生疑问：非农业户籍会使人更幸福吗？本文基于北京大学CFPS数据,构建了一个影响幸福程度的包括户籍因素在内的有序因变量模型。我们不但详述了户籍类型与居民幸福程度的内在联系机制,同时还分析众多主客观因素对幸福的影响。研究发现,户籍类型转变的实质是社会行动者基于户籍制度功能而做出的理性选择行为,不同时间和空间的户籍制度功能会引起幸福程度的差异;生活态度、人际和教育等因素也会显著影响幸福程度。因此,户籍制度改革过程中,重视户籍制度的功能而非形式是明智之举;同时,完善农村就业机制、增强个人自信心是提升社会行动者幸福程度的有效手段。     

On Generalized Binomial and Negative Binomial Distributions for Dependent Bernoulli Variables

We study the distributions of the random variables S_n and V_r related to a sequence of dependent Bernoulli variables, where S_n denotes the number of successes in n trials and V_r the number of trials necessary to obtain r successes. The purpose of this article is twofold: (1) Generalizing some results on the “nature” of the binomial and negative binomial distributions we show that S_n and V_r can follow any prescribed discrete distribution. The corresponding joint distributions of the Bernoulli variables are characterized as the solutions of systems of linear equations. (2) We consider a specific type of dependence of the Bernoulli variables, where the probability of a success depends only on the number of previous successes. We develop some theory based on new closed-form representations for the probability mass functions of S_n and V_r which enable direct computations of the probabilities.     

Estimation of Parameters of a Mixed Failure Time Distribution Which is a Mixture of Degenerate (Degenerate at Zero) and I. G. Distribution

The problem of estimation of parameters of a mixture of degenerate (at zero) and exponential distribution is considered by Jayade and Prasad (1990). The sampling scheme proposed in it is extended in this paper to a mixture of degenerate and Inverse Gaussian distribution. The Inverse Gaussian distribution is very relevant for studying reliability and life-testing problems. The inverse Gaussian being the first passage time distribution for Wiener process makes it particularly appropriate for failure or reaction time data analysis.