随机微分方程的几种参数估计方法

提出3种基于离散观测数据的随机微分方程参数估计的方法。第1种方法应用于线性随机微分方程。推导出这类方程的真解的相关运算服从的分布,使观测数据的运算也服从此分布,由此来估计漂移系数与扩散系数中的未知参数。第2种方法用于Itô型随机微分方程。推导出Euler-Maruyama格式的数值解的相关运算服从的分布,使观测数据的运算服从此分布,由此来估计参数。第3种方法用于Stratonovich型随机微分方程。推导出中点格式的数值解的相关运算服从的分布,使观测数据的运算服从此分布,以此来估计参数。数值实验验证了这3种方法的有效性。数值实验显示,Euler-Maruyama格式参数估计的误差约为O（h^0.5）阶,中点格式参数估计的误差约为O（h）阶,其中h是数值方法的时间步长。我们提出的3种估计方法均比文献中已有的EM-MLE方法更精确。     

Effect of a Brazilian Jiu-jitsu-simulated tournament on strength parameters and perceptual responses

This study aimed to analyse the effects of a simulated Brazilian jiu-jitsu (BJJ) tournament on vertical jump performance, grip strength test and perceived effort responses. 22 male BJJ athletes participated in a simulated tournament consisting of three 7 min matches separated by 14 min of rest. Kimono grip strength test (KGST), counter movement jump (CMJ) and rate of perceived exertion (RPE) were measured before and after each match, while RPE of specific areas was assessed after three matches. ANOVA for repeated measures was used to compare strength parameters after each match with the level of significance set at 5%. The key results showed a significant decrease of jump height (p = 0.001) and net vertical impulse in the CMJ (p = 0.031), as well as a reduction of the number of reps in the KGST (p < 0.001). A significant increase of RPE was found throughout the matches (p < 0.001). Considering the RPE in specific areas, no differences were observed between the upper and lower body (p = 0.743). We conclude that the BJJ simulated tournament generated a decrease of performance in both upper and lower limbs and provoked a progressive increase in the effort perception over the matches.     

Maximal heart rate declines linearly with age independent of cardiorespiratory fitness levels

There have been many conflicting observations between the linear or curvilinear decline in maximal heart rate (HR_max) with age. The aim of this study was to determine if linear or curvilinear equations would better describe the decline in HR_max with age in individuals of differing cardiorespiratory fitness (CRF) levels. Treadmill cardiopulmonary exercise test (CPX) results from participants (1510 men and 1134 women; 18–76 years) free of overt cardiovascular disease were retrospectively examined using cross-sectional and longitudinal study designs. Participants completing ≥2 CPX with ≥1 year between test dates were included in the longitudinal analysis (325 men and 150 women). Linear and quadratic regressions were applied to age and HR_max for the whole cohort and respective CRF groups (high, moderate, and low, relative to age and gender normative values). To test for differences among linear, quadratic, and polynomial equations, the change in R² (cross-sectional analysis) and Bayesian information criterion (BIC) (longitudinal analysis) from the linear to the more complex models were calculated. The quadratic or polynomial regression in the cross-sectional analysis, marginally improved the variance in HR_max explained by age compared to the linear regression for the whole cohort (0.2%), moderate fit group (0.3%), and low fit group (0.8%). With no improvements in the high fit group. BIC did not improve for any CRF category in the longitudinal analysis. In conclusion, the minimal differences among linear, quadratic, and polynomial equations in the respective CRF groups, emphasizes the use of linear prediction equations to estimate HR_max.     

房产税改革的方案选择及财税效应分析

对房产持有环节开征房产税具有国际通用的合理性和合法性,房产税改革是新一轮国家财税体制改革的重要内容。对国内主要城市的房产税改革方案及其财税效应分析表明：采用无差别税率征税方案的优势在于减少征管成本、确保居民纳税义务的公平性,劣势在于造成纳税人税负过重、不利于调节财富分配差距;而按住房面积采用递进税率征税方案的优势在于能够调节贫富差距、体现“量能负担”原则,劣势在于容易被纳税人投机取巧而逃避高税率和监管。权衡利弊,“每人享受一定面积的减免,根据住房面积大小、基于公告价值或评估价值按不同税率征收”的方案,可作为今后房产税改革的主要方向。     

高强度运动对心脏的冲击影响及信号提取研究

设计实时的肌肉组织血氧量和瞬时心率无损同步检测方案与设备,为研究高强度运动心脏的冲击影响、探讨高强度运动中代谢规律提供测试手段。方法:采用连续双波长近红外光测量肌肉中血红蛋白与肌红蛋白含氧量的变化情况;采用芬兰SUUNTO心率带和自行设计的转发器及配套PC软件测量瞬时心率,进行了100m跑同步实测试验。结果:100m跑以无氧代谢为主。起跑后的前7s为无氧代谢的非乳酸功能,肌氧饱和度曲线变化不大。7s后开始消耗肌肉中储存的氧。结论:双波长近红外光组织氧测试法和运动心率无线实时采集系统能够正确实时同步地检测高强度运动时血氧和心率,揭示了高强度运动过程中肌肉中氧的运输与消耗及心率之间的动力学过程。     

我国体育产业发展中公益与商业投资关系研究

我国体育产业从公益事业向产业化发展的过程中，始终面临着一个问题，那就是其中多大成分是公益，多大成分是商业，这个问题也导出了国家在体育公益事业上的投资与产业商业投资之间的合作、冲突和矛盾如何处理的问题。其实体育产业中的公益投资与商业投资具有相互促进、相互补充的关系，政府与企业之间可以相互融资，或者通过政府采购服务的方式，保证两种投资关系的合理和效益最大化。     

高校网球教学中学生网球兴趣的培养和提高

网球是一项非常有益身心健康的运动,可以帮助人们提高自身的运动能力、增强体质,很多高校开设了网球课程。如何提高学生对网球的兴趣,使其积极参与到网球课程中来成为了高校网球教学面临的主要难题。对此,笔者从高校当前的网球教学现状出发,为提高学生网球兴趣提出相应的建议。     

体育用品企业如何应对人民币升值的冲击

在分析我国体育用品市场现状的基础上，研究了人民币汇率变动的趋势以及汇率的变动对体育用品企业的影响，探讨了面临人民币升值的压力，如何趋利避害，合理利用国外生产要素，降低生产成本．及时归还和调整外汇债务，借鉴外国经验，大力推进对外直接投资。     

高校贫困生体育意识及兴趣形成的多因素调查分析

对贫困大学生的体育意识及兴趣形成的影响因素进行了调查分析,结果表明“性格特征”、“教育环境”是影响贫困生体育意识及兴趣形成的主要因素;影响贫困生和保障生的各个因素是一致的,学生贫困状况对体育意识及兴趣形成无显著影响。提出重视家庭、学校、社会多元化育人途径相结合等对策,以促进贫困学生身心健康发展。     

水平一段体育课“情境激趣”教学模式的构建与实践

依据新课程理念,探索在班级授课制条件下,实施以“情境激趣”的体育课堂教学模式。研究表明,通过情境激趣创新性学习,能激发学生运动的好奇心,积极参与体育活动,从而使学生持久保持学习体育的兴趣,能为学生的体育爱好转变成良好锻炼习惯打下基础。