北京奥运会抓台式与蹲踞式出发反应时的比较     

孙通 《体育科学研究》2010,14(3):86-89

通过文献资料、观察法、数理统计等研究方法,对北京奥运会游泳比赛中运动员采用蹲踞式和抓台式出发反应时进行统计与分析。结果表明：蹲踞式出发技术具有较好的稳定性、起动速度更快和发力效果好,比抓台式出发技术的反应时短,具有显著性差异,成为主流出发技术;建议：在各层次运动队的训练中广泛推广。  相似文献   

北京市高职院校篮球课教学现状调查分析     

王品 《哈尔滨体育学院学报》2010,28(5):69-72

采用文献资料、访谈、问卷调查、数理统计、逻辑分析等研究方法,对北京市高职院校篮球课教学内容与评价方法的现状进行了调查与分析。结果得出：北京市高职院校篮球课教学时数少,篮球教师性别比例不均衡,总体呈现年轻化趋势,北京市高职院校教师职称偏低,学历以本科为主,还有少数专科学历;北京市高职院校篮球教材和教学大纲一直沿用普通本科院校篮球教学大纲。  相似文献   

马琳在北京奥运会乒乓球比赛中的技战术运用分析     

程虹  白洁  钱来 《体育科技文献通报》2010,18(6):29-31

本文通过文献资料法、录像观察法、数理统计法、分段指标评估法,对马琳在北京奥运会比赛中的技战术进行了较深入的分析,得出结论：马琳的发抢优势明显,高质量的抢攻质是取得比赛胜利的关键。接发球段发挥最为稳定,是马琳取得比赛胜利的基础保障。相持段是马琳的薄弱环节;马琳在开局和尾局的战术运用过于保守;正手进攻能力突出,反手位特别是中远台进攻能力还有待进一步提高。  相似文献   

Static group synchronization of second-order multi-agent systems via pinning control     

Xiang-Gui Guo  Hong-Jian Li  Jun-Jie Zhao  Wei-Wei Che 《Journal of The Franklin Institute》2019,356(9):4842-4858

This paper investigates the expected static group synchronization problem of the second-order multi-agent systems via pinning control. For directed communication topology with spanning tree, based on Gershgorin disk theorem and the matrix property, a static pinning control protocol with fixed gains is first introduced and some sufficient and necessary static group synchronization criteria are also established. It is worth mentioning that a rigorous proof is also given that only one pinning node is needed to guarantee static group synchronization, which could be inferred that our protocol might be more economical and effective in large scale of multi-agent systems. Then, for weakly connected directed communication topology with nodes of zero in-degree, an adaptive pinning control applied to the node with zero in-degree is also proposed to achieve static group synchronization. Finally, the efficiency of the proposed protocols is verified by two simulation examples.  相似文献   

Chattering-free full-order recursive sliding mode control for finite-time attitude synchronization of rigid spacecraft     

Zhuoyue Song  Chao Duan  Jianan Wang  Qinghe Wu 《Journal of The Franklin Institute》2019,356(2):998-1020

This paper investigates a quaternion-based finite-time cooperative attitude synchronization and tracking of multiple rigid spacecraft with a virtual leader subject to bounded external disturbances. Firstly, the communication network between followers is assumed to be an undirected graph and every follower can get a direct access to the virtual leader, by using two neighborhood attitude error signals, a novel chattering-free recursive full-order sliding mode control algorithm is proposed such that all follower spacecraft synchronize to the virtual leader in finite time. In the proposed algorithm, the sliding mode surface is constructed by two layers of sliding mode surfaces, which are called as the outer and the inner sliding mode surfaces. To achieve finite-time performance of sliding mode dynamics, the outer sliding mode surface is designed as a terminal sliding mode manifold, and the inner one is designed as a fast nonsingular terminal sliding mode manifold, respectively. Then, to reduce the heavy communication burden, a distributed recursive full-order sliding mode control law is designed by introducing a distributed finite-time sliding mode estimator such that only a subset of the group members has access to the virtual leader. Finally, a numerical example is illustrated to demonstrate the validity of the proposed results.  相似文献   

Nonlinear optimal control with disturbance rejection for asteroid landing     

Shen Kang  Jianan Wang  Chaoyong Li  Jiayuan Shan 《Journal of The Franklin Institute》2018,355(16):8027-8048

This paper presents an optimal solution to asteroid soft landing problem, on the base of $\theta ?D$ control technique and disturbance rejection mechanism. The control objective is to drive a probe to reach the surface of an asteroid with a desirable line-of-sight angle and zero velocity, eliminating the influence of external disturbance. Firstly, elementary $\theta ?D$ technique is applied in the absence of disturbance to tackle the nonlinear optimal control problem. Secondly, the disturbance is estimated in the fast-estimation framework with explicitly bounded estimation error. Afterwards, an integrated control protocol is presented in a feed-forward structure by the aid of an additional variable-structure term to ensure stability under time-varying disturbance. Simulation results of the proposed approach compared with the results of elementary $\theta ?D$ method and robust $\theta ?D$ method are presented at the end of this paper, demonstrating the effectiveness of the proposed control protocol.  相似文献   

基于LEAP模型的北京公交集团碳减排政策情景研究     

赵立祥  汤静 《科技管理研究》2018,(2)

在对客运交通碳减排技术政策研究的基础上,构建北京市客运交通碳减排核算模型。采用带有情景分析的核算模型分析车辆和燃料改善的技术政策对于北京市客运交通碳减排的影响效果。研究结果表明,更新新能源和清洁能源车辆、执行更加严格的燃油消耗限值标准这两种技术政策均能在一定程度上降低CO2排放量。虽然提高燃油消耗限值标准政策在短期具有很好的减排效果,但长期来看不如更新新能源和清洁能源车辆减排作用明显。最后,对北京公交集团实现有效的碳减排提出应对策略和建议。  相似文献   

论北京奥运会的文化效应与大学生的和谐发展     

王颖 《吉林体育学院学报》2010,26(2):28-29

从文化、教育的角度审视,以体育为载体的奥林匹克运动对人的和谐发展具有独特的作用。借助北京奥运会的成功举办,对奥林匹克运动进行了深层的文化解读,并探讨了北京奥运会的文化效应对大学生和谐发展的积极作用,以期帮助大学生在实现以人为本、和谐发展的实践过程中自觉地去创造理想中的奥林匹克主义的生活方式。  相似文献   

对北京奥运会后我国大众体育发展策略的研究     

王永安  樊翠 《山西师大体育学院学报》2010,25(3):9-10,17

采用文献资料法和理论分析法,归纳总结了当前我国大众体育发展的特点与不足,认为现阶段我国大众体育仍然以政府管理为主,相对于竞技体育而言发展滞后,大众体育锻炼人口逐渐增多但老龄化问题严重。北京奥运会后,面对我国大众体育的发展,政府应该加大投入并有效整合社会资源,积极开展对外交流与合作,加大对大众健身项目的开发和研究力度,促进群众体育的协调发展。  相似文献   

女排不同拦网阵型下的36种进攻组合效果研究     

屈东华  张岩 《北京体育大学学报》2010,(1)

采用攻防组合法和逻辑分析法等,对2008年北京奥运会女排四强之间的7场比赛进行统计。从不同拦网人数的角度下分析进攻中36种组合方式的情况,揭示在不同拦网人数下进攻上存在的差异与规律,为女排今后的发展提供理论指导。同时,为进一步研究高水平排球运动的制胜规律提供参考。  相似文献