现代"体育"概念几个问题的探讨

现代"体育"概念的长期混乱有其国际上的根源、翻译上的根源和认识上的根源.对体育总概念内涵的认同和正确表述有赖于对体育各基本形态的共同特殊性进行哲学层面的分析和概括.体育总概念的某些相似概念使用频繁,亦需尽快规范.     

一种平面四连杆机构轨迹综合的新方法

根据平面闭合曲线切线象理论，定义了切线全旋转角的概念，提出并论证了一种用曲线的曲率关于切线全旋转角的函数和进行平面四连杆机构轨迹综合的新方法。这是一种可应用于工程设计的几何系统分析法。     

扩号借号法的3处新例证

论文对《中图法》第4版中新发现的3处扩号借号法例证，从类级分析、并非特殊八分法类号辨析、并非加“0”类号辨析和并非下借法类号辨析等方面进行了论证。     

One hundred and fifty years of sprint and distance running – Past trends and future prospects

Sprint and distance running have experienced remarkable performance improvements over the past century. Attempts to forecast running performances share an almost similarly long history but have relied so far on relatively short data series. Here, we compile a comprehensive set of season-best performances for eight Olympically contested running events. With this data set, we conduct (1) an exponential time series analysis and (2) a power-law experience curve analysis to quantify the rate of past performance improvements and to forecast future performances until the year 2100. We find that the sprint and distance running performances of women and men improve exponentially with time and converge at yearly rates of 4% ± 3% and 2% ± 2%, respectively, towards their asymptotic limits. Running performances can also be modelled with the experience curve approach, yielding learning rates of 3% ± 1% and 6% ± 2% for the women's and men's events, respectively. Long-term trends suggest that: (1) women will continue to run 10–20% slower than men, (2) 9.50 s over 100 m dash may only be broken at the end of this century and (3) several middle- and long-distance records may be broken within the next two to three decades. The prospects of witnessing a sub-2 hour marathon before 2100 remain inconclusive. Our results should be interpreted cautiously as forecasting human behaviour is intrinsically uncertain. The future season-best sprint and distance running performances will continue to scatter around the trends identified here and may yield unexpected improvements of standing world records.     

A dynamic decision model for portfolio investment and assets management

This paper addresses a dynamic portfolio investment problem. It discusses how we can dynamically choose candidate assets, achieve the possible maximum revenue and reduce the risk to the minimum level. The paper generalizes Markowitz's portfolio selection theory and Sharpe's rule for investment decision. An analytical solution is presented to show how an institutional or individual investor can combine Markowitz's portfolio selection theory, generalized Sharpe's rule and Value-at-Risk(VaR) to find candidate assets and optimal level of position sizes for investment (dis-investment). The result shows that the generalized Markowitz's portfolio selection theory and generalized Sharpe's rule improve decision making for investment.     

一类广义Liénard型方程的极限环

本文讨论广义Lienard系统(E):x+(f(x)+k(x)x)+g(x)=0,获得了系统(E)的极限环存在,至多有一个或两个的充分条件.这些条件不仅简单和易于验证,而且推广了〔5,6〕的结果.     

钢材高温下应力-应变曲线研究

火灾是影响钢结构设计的最主要因素.对钢结构抗火设计的现行方法进行了分析,并指出各种方法所存在的缺陷,通过对钢结构抗火力学性能的研究,参照欧洲标准对常见钢材高温下应力-应变性能进行了分析与计算,得出了便于使用的应力-应变关系.     

一对称矩阵方程组解的研究

给出了四元数体上一对称矩阵方程组有斜埃尔米特解的充分必要条件,并得到了此方程组的斜埃尔米特解的一般表达式。应用主要结果讨论了四元数矩阵A和B矩阵有共同的斜埃尔米特广义逆的充要条件及斜埃尔米特广义逆的表示。     

SASW法在公路复合地基检测中的应用

介绍了瑞雷波法(SASW法)的基本原理与测试方法,并通过工程实例说明SASW法在公路复合地基加固深度的检测方面以及均匀性检测方面具有良好的应用效果。地基的承载力(包括复合地基承载力)往往难于确定,本文总结了利用瞬态瑞雷波法确定地基承载力的方法及瑞雷波速度与地基承载力的经验关系式,但该关系式具有一定的局限性、地区性,建议在以后的实践应用中仍需继续积累对比资料,不断补充修正。     

清江源头Streeter-Phelps模型分析

本文以清江源头为研究对象,利用室内碘量法实验获得针对清江源头附近的Streeter-Phelps模型的耗氧系数以及复氧系数,得到清江源头附近河段的氧垂曲线,根据曲线求得极限溶解氧、极限氧亏、极限距离,预测河水含氧量的变化。