气排球垫球的创新技术及其训练方法

由于气排球规则和自身的特性,决定了气排球的垫球技术与传统硬式排球的垫球技术不同,且有所创新。着重就气排球垫球的创新技术动作挡搬球、捞球、捧球、抓球、单手托球等进行细致地分析,并提出相应的训练方法,为广大气排球教练员、运动员和爱好者提供借鉴。     

程序教学法在高校排球基本技术教学中的运用

对排球基本技术教学内容进行程序优化设计和教学实验,结果表明,“程序教学法”优化了教学结构和教学过程,在教学内容上具有“化难为易,化繁为简”的作用,有利于学生加深对所学技术的理解和运用能力的增强;能够充分发挥教师的指导作用与学生的主体作用;并能及时反馈教学效果,使教授环节和学习环节相对应、相联结,使教学过程系统而优化,从而明显提高了教学效率和质量。     

铝合金表面高耐磨自润滑硬质阳极氧化膜的制备

以硫酸、草酸、氨基磺酸为基础电解液,分别添加0,5,15和25mL/L的PTFE乳液,在2024铝合金表面制备了PTFE复合硬质Al2O3氧化膜.利用扫描电镜、硬度计和摩擦磨损试验机等手段,对制备氧化膜的组织结构与性能及其复合机理进行了研究.结果表明:随着PTFE添加量的增加,氧化膜的厚度由没有添加PTFE样品的42μm增加到了51μm;硬度呈现先增加后降低的趋势,硬度最高为417HV.当PTFE乳液的添加量为25mL/L时,磨损时的失重量为7mg,是没有添加PTFE颗粒样品的三分之一.磨损时复合在氧化膜中的PTFE与对摩擦件接触时可形成润滑膜层,在保持高硬度的同时降低了摩擦系数,提高了膜的耐磨和自润滑性能.     

Hard X-ray free-electron laser based on echo-enabled staged harmonic generation scheme

A novel approach to producing coherent hard X-ray based on the echo-enabled staged harmonic generation (EESHG) free-electron laser scheme is proposed. This scheme is not a simple cascaded echo-enabled harmonic generation (EEHG) but consists of an EEHG and a conventional high-gain harmonic generation (HGHG) like configuration, which also works in the EEHG principle. It is shown that fully coherent hard X-ray radiation can be obtained directly from a conventional VUV seed laser with reduced size and cost in c...     

浅谈沙滩排球的防守配合

沙滩排球是一项新兴的体育运动项目．着重对其防守中的制定计划、拦网、选位和心理素质等问题，作了简要的论述．     

Temperature dependence of the static structure factor of the non-simple liquid metal,Cd

Report a calculation of the static structure factors at any temperature for the non-simple liquid metal Cd by the method of model parameter based on the hard sphere cluster (HSC) model. In comparison with available experimental data, the theoretical results are in good agreement with experiments. Supported by the National Natural Science Foundation of China Ren Dazhi: bron in Nov. 1948, Lecturer     

风化煤用于硬水软化的规律及其软化能力的研究

我们曾研究过风化煤对硬水的软化,证明了风化煤对硬水有显著的软化作用,本文进一步研究了用风化煤软化硬水的一些条件、规律及其软化能力,以便实际应用于工业水处理。并对所处理的水进行了结垢试验,证明了该法处理的水具有较高的防结垢能力。     

Progress in material removal mechanisms of surface polishing with ultra precision

Chemical mechanical polishing (CMP) process is commonly regarded as the best method for achieving global planarization in the field of surface finishing with ultra-precision. The development of investigation on material removal mechanisms for different materials used in computer hard disk and ultra-large scale integration fabrication are reviewed here. The mechanisms underlying the interaction between the abrasive particles and polished surfaces during CMP are addressed, and some ways to investigate the polishing mechanisms are presented.     

聚脲氨酯的合成与表征

由于胺类化合物与异氰酸根的强烈反应活性,在以二胺作扩链剂合成聚脲氨脂(PEUU)材料时多采用溶液两步法。但此方法周期长,受溶剂中水影响大,不易控制,尤其在夏天高温高湿季节,成功率很低。本文扼要叙述一种先本体后溶剂的新合成方法,此方法操作简便,容易控制,并对合成结果分别用红外光谱(IR)、宽角X射线衍射(WAXD)、小角X射线散射(SAXS),热机械分析(TMA)、扫描电子显微镜(SEM)等技术对合成样品进行了表征。     

MA组元对焊接热影响区粗晶区断裂行为的影响

将高强钢焊接热影响区中硬化组织ＭＡ组元视作局部硬化区，采用二维有限元数值方法讨论了含ＬＨＺ材料的断裂机理。结果表明，含细长ＭＡ的热影响区比含块状ＭＡ的热影响区容易产生裂纹，这一结果在高强钢焊接影响区ＣＴＯＤ试验中得到证实，因此控制ＭＡ组元形状能够改善焊接影响区的韧性。