Characteristics of entropy generation and heat transfer in a microchannel with fan-shaped reentrant cavities and internal ribs

Three-dimensional laminar fluid flow and heat transfer in a micro heat sink with cavities and internal ribs are investigated us-ing numerical methods. Moreover, according to the second law of thermodynamics, the model of entropy generation is also established for variable cross section of the microchannel. The simulation encompasses Reynolds number of 198-600, relative cavity height e1/Dhvalues of 0-0.65, relative rib height e2/Dhrange of 0-0.2167. The results show that the effect of relative rib height on entropy generation is significant, while the relative cavity height has little effect on it. The combined effect of cavities and ribs in the microchannel has better performance of heat transfer than the smooth microchannel under similar conditions. Extensive simulations are conducted to collect data on the characteristics of heat transfer and fluid flow in a micro heat sink with cavities and internal ribs. Using these data, correlations for Nusselt number and friction factor in terms of Reynolds number and the geometry of cavity and rib have been developed.     

Effect of austenite grain size and accelerated cooling start temperature on the transformation behaviors of multi-phase steel

The transformation behaviors and microstructures of a low carbon multi-phase steel were investigated by the simulation of deformation-relaxation-accelerated cooling processing,using a Gleeble 3500 thermal-mechanical simulator.A pre-treatment of solid solution at 1200°C was implemented to minimize the influence on transformation from solid solution/precipitation qualities of 0.08%Nb in this steel.On this basis,the effect of austenite grain size and accelerated cooling start temperature were studied individually.The results indicated that the transformation of ferrite in multi-phase steel could be significantly promoted by the refinement of austenite grains and the increase of relaxation time,while the hard phase,such as lath bainite or martensite,could still be obtained with the following accelerated cooling.In contrast,more uniform lower temperature transformed microstructure could form from coarse grain austenite.The potential benefit of austenite grain size on adjusting the proportion of phases in multiphase steel was also discussed.     

亭子口缆机运行效率提高的工作研究

根据缆机浇筑混凝土的工艺特性,将缆机浇筑混凝土过程中的车辆运输及缆机吊运程序进行作业流程分解,将缆机吊运作业周期划分为9个操作单元,采集缆机吊运混凝土过程中卸料和浇筑全周期各单元的50个工作样本数据进行统计分析,找出需改进的关键点,针对性地提出了6项改进措施.改进作业方案后缆机吊运混凝土的效率提高了约20％.     

小云峰水电站右岸副坝渗水处理

小云峰水电站右岸副坝为混凝土重力式自由溢流坝。坝基岩质坚硬,裂隙较发育。推荐处理设计方案为:在溢流坝坝面以下2m采用伸缩性(柔性)化灌材料(聚氨酯类)灌注满,使坝缝内的水不从坝面渗出,同时保证一定的抗冻深度,排水孔、灌浆孔、排气孔均采用斜孔,避免破坏止水。     

军校营造良好学风的几点思考

针对当前军校学风建设存在的问题,从加强思想教育、完善教学管理制度、发挥队干部良好的导向作用、加强教风建设及落实教学管理制度等方面提出了军队院校营造良好学风的对策.     

关于复正规矩阵的Rayleigh商

将Hermite矩阵的Rayleigh商推广到了复正规矩阵中,研究了复正规矩阵的Ray-leigh商的一些性质,其结果具有一定的理论价值和应用价值。     

执政党建设与当代执政文化转型

着重研究了马克思主义执政党建设如何应对当代世界政党政治的执政文化转型问题,认为应当正确认识和处理马克思主义执政党建设与当代世界政党政治的关系,深入研究世界上其他执政党治国理政的成功经验和有益做法,不断提高马克思主义执政党的执政能力和科学化水平。     

时空结构视野下旅游客源市场定量初探——以浙江嘉兴乌镇为例

在客源时间分布上,计算乌镇游客游览时间强度指数,得到游客游览时间主要集中在二、三季度,并以7、8月份为最高峰。而在客源市场的分布上,鸟镇已经形成了以浙江为核心,上海、北京等地为一级,安徽、河南等地为二级的国内客源市场。在长三角古村落旅游发展迅速的今天,乌镇与周边的周庄、同里等古镇的竞争日益激烈,而旅游产品的创新、加大宣传迅速占领国内二级客源市场等措施将有助于乌镇在竞争中脱颖而出,占领主导地位。     

超细片状铝粉和铝银浆的制备

超细鳞片状铝粉和铝银浆由于其特殊的二维平面结构，具有良好的遮盖力、显著的屏蔽效应、光学反射能力；超细鳞片状铝粉和铝银浆颜料的制备方法很多，本文采用机械化学法制备超细鳞片状铝粉和铝银浆。     

ZF12-145(L)气体绝缘金属封闭开关设备断路器

介绍了ZF12-145（L）三相共箱式气体绝缘金属封闭开关设备断路器的技术参数、性能、灭弧室的计算分析和主要特点.