时间与中外叙事作品中的时间表现

时间是最早引起人类关注的自然现象之一。在不同语言、文化、民族、地域和国家的叙事作品中,时阈的表现以不同的方式呈现出来,其中最为明显的差别就是线性与空间性的表现。这种不同的表现方武具有内在的文化意义。古代印度的叙事作品在时间上具有明显的空间性的特征：以古希腊史诗与悲剧为代表的西方文学则明显地具有线性叙事的特征。中国古典叙事文一开始便具有对时间的关注．展现出明显的线性叙事特征。形成了众多各具特色的叙事文。在对叙事文时间表现的研究中,清代学者李绂取得的成就令人瞩目．在这一领域开风气之先。     

Pick a Number … Any Number?

A recent classroom revelation caused us to reconsider the adequacy of the instructions offered in our textbooks for one of our most elementary quantitative methods. Specifically, we found that many students were mystified concerning how to pick an initial objective function value when plotting an isoprofit line in order to graphically solve a linear programming problem. We observed that this seemingly insignificant issue was causing a surprising amount of wasted time, confusion, and even anxiety. Our experience indicated that students do not necessarily possess any consistent intuition for choosing an appropriate initial value. We confirmed this perception through informal experimentation. We reviewed several textbooks and found that most simply do not bother to address this issue. Therefore, we devised a simple, comprehensible method which we have taught our students to resolve or avoid this problem. Although we quickly found the method to be helpful for many students, we conducted an experiment to formally measure its effect.     

线性多步法拉格朗日形式的导出方法

本文利用Taylor展开、待定系数法、数值积分和数值微分法来讨论线性多步法一般形式公式的构造方法。     

半群方法在求解微分方程中的应用

运用半群方法对两类方程求解,得到具有简单形式的方程的解,推广了特殊方程的求解方法．     

求解奇异线性方程组的双逐次投影法

用双逐次投影迭代法来求解奇异线性方程组,当线性方程组的系数矩阵是对称半正定时,给出了不同情形时有关参量的选取以及相应的算法,并就收敛结果分别与雅可比迭代法和Gauss-Seidel迭代法进行了比较,数值结果表明,该方法对求解奇异线性方程组是很有效的.     

从线性到非线性:企业成长理论回顾、现状与展望

从最初企业是生产函数、契约到企业是复杂适应系统的认识深化,企业成长的理论研究开始从线性向非线性过渡。本文以企业成长理论从线性到非线性转变为主线,梳理企业成长理论的演进脉络。通过对众多理论之间的内在逻辑关系及其适用边界和应用性分析发现,非线性在企业成长过程发挥了主导作用,并指出从内生和外生两方面互动的视角建立非均衡、非线性有机统一的企业成长机制,可对企业成长规律给出更合理的理论解释。     

联合预测在中国人口总量预测中的应用

人口问题是制约中国经济发展的重大问题之一,实行计划生育以来,我国的人口增长水平虽然放缓,但由于人口基数庞大,人口的增长数量仍然相当的可观,因此,准确的预测未来总人口数量对于制定相应的政策法规以保证经济的快速发展具有重大意义。基于过去年份的人口数据,利用ARIMA模型和回归模型来预测未来中国的人口数量,并利用联合预测将两种预测结果进行加权平均,以达到更高的预测精度,为人口预测提供了一种简单高效的预测模型。     

环Z~4上几类线性码的深度谱

文章主要研究环Z4上线性码的深度谱,对于一般的4K12K2型线性码与相应的2K型子码的深度谱之间的关系进行了研究,并给出了几类满足特定条件的线性码的深度谱.     

悬臂梁受线性分布荷载的辛解答

与传统的半逆解法不一样,采用弹性力学平面直角坐标系辛体系,运用分离变量法,求出矩形梁非齐次边界条件的解.辛解法能够有效处理各种边界条件,特别是矩形梁受线性分布荷载时,显示该方法的有效性.     

Effect of endpoint conditions on position and velocity near impact in tennis

Smoothing to obtain accurate position and velocity data near impacts in sport biomechanics studies is complicated by the accelerations of impact, endpoint effects and the smoothing technique used. Wrist goniometric data with two levels of random noise added were used to examine three endpoint modelling conditions for obtaining accurate position and velocity data at impact in the tennis forehand. The common approach of smoothing through impact created distortions of the position signal up to 100 ms before impact and resulted in consistent underestimations (-3.2%) of wrist angle and angular velocity (-67.9%) at impact. New linear and polynomial extrapolation conditions smoothed with all techniques provided lower root mean squared errors than the smoothing-through-impact condition, with discrete wrist positions at impact within 1.1% of the criterion data. Both the new linear and polynomial conditions can be used to make more accurate angular position and velocity estimates for tennis impacts, whereas the smoothing-through-impact condition creates spurious decreases in speed before impact that in the past have been assumed to be aspects of skilful movement.