三自由度并联式波浪补偿平台建模与仿真

鉴于船舶在波浪中的六自由度运动中,其升沉、横摇和纵摇运动对船舶工作平台上的设备影响较大,设计一种三自由度并联式波浪补偿平台来减少这种影响。通过对平台进行运动学分析,得到平台的运动学模型。利用ADAMS和Simulink建立带有控制系统时间延迟参数的虚拟样机模型,依据平台的运动学模型设计对船舶运动进行补偿的控制策略,并利用虚拟样机进行仿真,验证平台机构和相应控制策略对船舶运动的补偿效果。结果表明:当控制系统的时间延迟参数取值为1 ms时,平台对船舶升沉、横摇和纵摇运动的补偿效果分别为88.81%、95.44%和91.97%;当控制系统的时间延迟参数取值为0.1 ms时,平台对船舶升沉、横摇和纵摇运动的补偿效果分别为96.04%、99.07%和97.65%。由此可见:平台对误差有一定的包容性;可利用具有船舶运动预测功能的算法为平台提供超前的船舶运动数据或者提高控制系统的实时性来提高补偿效果。     

乒乓球运动员以预防损伤为主的功能训练

功能训练的理念来源于康复领域,现已逐步应用到运动训练中。由于乒乓球运动的项目特征,乒乓球运动员肩关节、腰椎关节、膝关节、踝关节、腕关节等部位容易出现运动损伤。通过对乒乓球运动员常出现的功能问题进行分析,寻找存在的常见问题,进而提出相应的功能训练建议。乒乓球运动员可根据情况,增加改善肩关节、胸椎关节、髋关节、踝关节的活动范围的训练,提高肩胛骨、核心和下肢稳定性的训练,以及改善肩袖、躯干肌力不平衡的训练,通过针对性的功能训练有效减少乒乓球运动员损伤的发生。     

Examining the influence of grip type on wrist and club head kinematics during the golf swing: Benefits of a local co-ordinate system

Wrist movements have been identified as an important factor in producing a successful golf swing, with their complex motion influencing both club head velocity and orientation. However, a detailed analysis of wrist angles is lacking in the literature. The purpose of this study was to determine kinematics across wrists and club head characteristics during the golf swing under weak, neutral and strong grip conditions. Twelve professional male golfers executed 24 shots using a driver under three grip conditions. A six degrees of freedom analysis of the hand with respect to the distal forearm was performed using a 10-camera three-dimensional motion capture system. Differences in joint angles were explored using repeated measures ANOVAs at key swing events (onset, top of backswing and impact), in addition club head velocity and clubface angle at impact were also explored. Main findings revealed significant differences in flexion/extension and internal/external rotation for both wrists at all swing events, whereas fewer significant interactions were found in ulnar/radial deviation across grips for both wrists at all events. Clubface angle only differed significantly between the weak and the strong and neural grips, presenting a more ‘open’ clubface to the intended hitting direction. This study is the first to explore tri-planar wrist movement and the effect of different grips, such analysis has implications for coaching knowledge and practice and should inform future research into different aspects of skill, technique analysis and may inform injury mechanisms/prevention.     

Contextual factors on physical demands in professional women’s soccer: Female Athletes in Motion study

The aim of this study was to examine the impact of contextual factors on relative locomotor and metabolic power distances during professional female soccer matches. Twenty-eight players (forwards, n?=?4; midfielders, n?=?12; defenders, n?=?12) that competed in a 90-min home and away match (regular season only). The generalised estimating equations (GEE) was used to evaluate relative locomotor and metabolic power distances for three contextual factors: location (home vs. away), type of turf (natural vs. artificial), and match outcome (win, loss and draw). No differences were observed for home vs. away matches. Moderate-intensity running (20.0?±?1.0?m?min^?1 and 16.4?±?0.9?m?min^?1), high-intensity running (8.6?±?0.4?m?min^?1 and 7.3?±?0.4?m?min^?1) and high-metabolic power (16.3?±?0.5?m?min^?1 and 14.4?±?0.5?m?min^?1) distances were elevated on artificial turf compared to natural grass, respectively. Relative sprint distance was greater during losses compared with draws (4.3?±?0.4?m?min^?1 and 3.4?±?0.3?m?min^?1). Overall physical demands of professional women’s soccer were not impacted by match location. However, the elevation of moderate and high-intensity demands while playing on artificial turf may have implications on match preparations as well as recovery strategies.     

基于多系数保角变换法的船舶垂荡纵摇运动仿真

为给航海模拟器建立实用可靠的船舶在波浪中运动的数学模型,基于二维线性势流理论,采用多系数保角变换法对每个船舶横剖面进行高精度拟合,计算各个横剖面的水动力系数和波浪激励力,利用Visual Studio自主开发出船舶在规则波中的纵向运动数值模拟程序。为验证这个数值模拟程序的可靠性,对S175集装箱船在迎浪中运动的幅值响应因子(response amplitude operator, RAO)进行数值计算。结果表明:当弗劳德数为0.275时,RAO计算结果在大部分频率范围内与试验结果吻合良好。因此,这个数值模拟程序能准确地对船舶在波浪中的运动时历进行仿真。     

论商业广告的性质——兼论消费者对虚假广告的民事赔偿请求权

在我国采取虚假广告欺骗消费者,给消费者造成损失的事情时有发生。但要从法律上规范广告行为,赋予消费者民事赔偿请求权是一个重要的手段。根据广告的法律性质,消费者对于虚假广告的民事赔偿请求权主要有两种,一种是基于缔约过失责任的请求权,另一种是基于单方行为说引出的违约责任的民事赔偿请求权。     

清代山西学田考

学田制度是我国古代的一种赡学制度。清代学田在明代基础上得到进一步发展,成为清政府教育财政支出的重要补充。清代山西学田有其自身特点,具有一定的代表意义。     

股权集中度、经理人激励与技术创新选择

基于委托代理理论及技术创新理论,探讨股权集中度对企业技术创新选择的影响。以182家制造企业及高新技术企业数据为样本,利用因子分析及结构方程模型对相关假设进行检验。结果表明:(1)经理人激励在股权集中度和技术创新之间具有中介效应;(2)股权集中度和经理人短期薪酬激励呈负相关,和经理人长期薪酬激励呈正相关;(3)短期薪酬激励不利于突变创新,长期薪酬激励有利于突变创新和渐进创新。     

无米下锅抑或激励不足？政府补贴、企业绿色创新与高管激励策略选择

绿色创新已成为驱动中国制造业转型的重要路径。过度依赖科技政策的外生冲击而忽略企业内生激励机制,容易造成创新平滑失效和公共资源的配置扭曲。本文从财税政策与公司治理双重层面,重点探讨政府补贴与高管激励对企业绿色创新的整合影响。研究显示,薪酬激励的创新补偿效应能够提升财税补贴政策对企业绿色创新的平滑效果;相比之下,声誉激励对财税补贴与绿色创新关系的影响并不显著;薪酬激励与声誉激励的互补关系催生了激励组合的创新补偿效应,在薪酬激励强度适中的条件下,财税补贴能够实现对绿色创新的最优驱动作用。本文能够从公司治理视角揭示财税补贴创新悖论的成因,并为优化政府财税政策和企业创新激励机制,推动中国制造业绿色发展提供科学依据。     

金华江流域生态服务补偿支付意愿及其影响因素分析

流域环境服务的提供者和与同一环境服务的使用者或受益者在空间上的分离,以及生态补差机制的缺位使生态系统管理者没有通过经济激励去改善环境管理,从而导致环境服务供给不足,服务质量低下.本文利用条件价值法(Contingent Valuation Method,CVM)评估金华江流域居民环境服务的支付意愿,并利用Ordered Probit模型和Binary Probit模型分别分析了最大支付意愿及其支付方式的影响因素.结果显示:金华江流域的居民中有78.4%的居民家庭具有支付愿意,平均最大支付意愿E(WTP)为24.87元/(户·月),年平均最大支付意愿为298.46元/(户·年).最大支付意愿与受教育程度、收入水平呈显著的正相关关系,环境相对经济的重要性对最大支付意愿没有显著的影响,了解生态保护概念的受访者平均最大支付意愿并不高于那些不了解的人,这反映了人们对环境保护的认识与行为偏差和"搭便车"侥幸心理.受教育程度与环境相对经济的重要性越高,则选择交生态补偿税的概率也越高;性别、年龄、是否经历过污染灾害与最大支付意愿对人们支付意愿补偿方式的选择都没有显著的影响.实施生态补偿政策,必须促进上下游农户和居民、相关企业和地方政府等利益相关者直接参与到流域管理和决策中,实现流域环境共建和利益共享,在此基础上构建流域生态补偿体系.