基于核密度估计多样性采集的背景建模算法

1IntroductionBackground subtraction methods are extensively ex-ploited for moving object detection in videos in manyapplications ,such as traffic monitoring[1],human mo-tion capture[2]and video surveillance[3]. The centralidea behind such methods is to segment foreground ini mage sequences taken from a fixed camera by com-paring each newframe to a model of the scene back-ground . Therefore , correctly and efficiently modelingand updating the background model is one of the mostchallenging aspec…     

民营企业后发展阶段应加强企业文化的长期激励作用

民营企业后发展阶段是指中小型民营企业在获得第一桶金后，开始逐渐进入成长阶段，由以市场营销为中心，以利润为主要目标的经营型管理模式向以战略谋求企业长期生存与发展的战略型企业转变的阶段。     

初教专业历史课程设置及教学浅议

随教育事业的发展，素质教育的深入，三级师范已不能满足小学教育的需要，在一些教育发达地区已实现师范教育本科化。由于我省基础薄弱，最近几年才进行初教专业的探索，笔在承担初教专业历史教学任务，经过几年的探索性教学实践后，对我省五年制师范课程中关于历史课程的设置及教学方面应合理安排课程设计，采用较为合理的教学方法与手段，使学生知识理论与教学技能获得全面发展作一些探索。     

Conversion of CO<Subscript>2</Subscript> to useful substances with composite iron,nickel, and copper catalysts

Composite materials of Fe/Al₂O₃, which consist of small particles of iron supported by thermally stable alumina even at 500–700 °C, have been widely used in the water-gas shift reaction for natural gas reforming. Therefore, Fe/Al₂O₃ is one of the promising candidates for re-transformation of exhausted CO₂ into fuels such as alcohols and hydrocarbons. The development of a CO₂ reforming system using the composite materials of Fe/Al₂O₃ through CO₂ reduction to CO, dissociation of water into hydrogen, and methanol synthesis has been investigated. It was found that dry and steam (i.e. wet) reforming of CO₂ produced almost the same amount of CO. At a temperature above 500 °C, maximal and saturated yields of CO and H₂ from CO₂ and water were obtained. However, this CO₂ reforming system requires higher-pressure conditions from several tens to hundreds standard atmospheric pressure in order to achieve high yield and selectivity for methanol production. In this study we developed the modified CO₂ reforming system by the utilization of Ni and/or Cu instead of Fe in order to obtain other types of useful products such as CO, CH₄, and carbon, more efficiently and selectively under atmospheric pressure. When Ni or Cu was used, conversion of CO₂ was reduced to 76%, while 9% of methane was detected in the case of Ni. On the other hand, though the CO₂ conversion reduced half of the Fe, the selectivity of CO from CO₂ increased to 95% in the case of Cu.     

Numerical investigation of cavitating flow behind the cone of a poppet valve in water hydraulic system

Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNGk-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43000. The working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model. Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera. The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good agreement with the numerical result. Project supported by the National Natural Science Foundation of China (No. 59835160) and Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry of China (No. 50175097)     

英语作文写作技巧初探

大学生普遍认为英语写作比较难,究其原因,造成学生写作难的主要因素大致有以下几个方面:词汇贫乏、语言障碍和写作技能的生疏等.因此,大学生只要在平时的学习中多实践、多模仿,注意文章的构思、段落设计和文章连贯性等因素,就一定能写出一手好的英语文章.     

谈对艰苦创业精神教育的认识

随着经济的发展，人民生活水平的提高，全面建设小康社会目标的确定，进一步加强思想道德建设，大力提倡勤俭建国，艰苦奋斗的创业精神的重要性和必要性在当今社会仍然具有重要意义。     

Filtration of micro-particles within multi-fiber arrays by adhesive DEM-CFD simulation

A 3D multi-time scale discrete element method-computational fluid dynamic (DEM-CFD) coupling approach was applied to investigate the filtration of micron-sized particles by different types of fiber arrays. Both the pressure drop and the filtration efficiency were examined to indicate the filtration performance of the fiber arrays. Fibers that were uniformly arrayed in a parallel or staggered manner were compared. Results showed that the staggered array showed a better performance than the parallel array in terms of both pressure drop and filtration efficiency. Further, we compared the performance of different staggered arrays, i.e. a regular case, one densified in the front layers and another densified in the back layers. The front densified array was found to enter the clogging and cake filtration stage in the shortest time, leading to the highest filtration efficiency, but the highest pressure drop. The back densified array still achieved a much higher filtration efficiency, despite a much lower pressure drop comparable to that of the regular array. The results suggest that the two kinds of densified arrays may be suited for different purposes, e.g. baghouse filters or breathing masks.