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)     

高等师范院校学生两项资助政策的研究

按国家有关政策的规定，师范生享受专业奖学金和免缴学杂费、住宅费的待遇。通过调查25个省、市、自治区的35所师范院校近几年执行上述两项资助政策的实际情况，提出改革现行资助政策的设想：收费政策与其他院校并轨；在学资助与职后资助并举，以职后资助为主。     

高职高专英语专业“任务型”教学现状调查及研究

课题组对我省三所具有代表性的高职高专院校（英语专业）大二的师生进行了调查，主要采用问卷调查和访谈的方式，通过数据处理，分析目前海南高职高专院校中英语专业（综合英语）教学现状及存在问题。提出激活英语课堂的方法之一——任务型英语教学。     

草苁蓉花序多糖BJⅡa的分离提纯与结构研究

利用溶剂提取与DEAE—Sephadex A—25柱层析进行分离,根据高碘酸氧化、Smith降解,部分酸水解、甲基化及其产物的G.C.和G.C.—M.S.联机分析鉴定其结构.得出BJⅡa是多分枝结构的中性杂多糖,其主链是由1→2连接的葡萄糖和岩藻糖构成。     

用Authorware实现CAI课件中动画的交互播放

用多媒体创作工具Authorware开发多媒体CAI课件时 ,可以通过几种方法灵活方便地实现动画的交互播放 ,实现以学生为主体的个别化教育 ,达到良好的教学效果     

生态安全问题的全球观与战略对策

世界各方面的迅速发展，使生态安全问题全球性更加突出。加强国际合作、采取统一行动，实施资源技术、生态圈、社会心理等生态战略，是势在必行的。     

中国传统意象性思维的当代价值

思维活动的意象性是中国传统思维方式的本质特征。文章系统考察了意象性思维的起源、发展过程、基本特征和当代价值。指出，中国传统的意象性思维方式与当今信息时代有高度的相融性。对意象性思维的创造性转化，既可以提高我们的心理生活质量，又可以增进我们的认知能力，是当代心理学研究不能回避的重要课题。     

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.     

A novel multi-objective optimization method for the pressurized reservoir in hydraulic robotics

The pressurized reservoir is a closed hydraulic tank which plays a significant role in enhancing the capabilities of hydraulic driven robotics. The spring pressurized reservoir adopted in this paper requires comprehensive performance, such as weight, size, fluid volume, and pressure, which is hard to balance. A novel interactive multi-objective optimization approach, the feasible space tightening method, is proposed, which is efficient in solving complicated engineering design problems where multiple objectives are determined by multiple design variables. This method provides sufficient information to the designer by visualizing the performance trends within the feasible space as well as its relationship with the design variables. A step towards the final solution could be made by raising the threshold on performance indicators interactively, so that the feasible space is reduced and the remaining solutions are more preferred by the designer. With the help of this new method, the preferred solution of a spring pressurized reservoir is found. Practicability and efficiency are demonstrated in the optimal design process, where the solution is determined within four rounds of interaction between the designer and the optimization program. Tests on the designed prototype show good results.