论企业适合、适时、适度多元化

多元化经营是企业扩大经营规模、规避经营风险，追求协同效应的重要战略选择。但近几年来，我国许多朝阳企业却因盲目涉及多元化而改走麦城，一蹶不振，本文经过充分论证，提出企业采取多元低级战略应注意适合、适时、适度的问题。     

用预应力措施处理连续结合梁中负弯矩区

连续结合梁中负弯矩区混凝土桥面板会因承受较大拉应力而开裂,会引起钢筋及钢梁腐蚀等严重问题,影响结构的承载能力和耐久性。文章分析和介绍了对负弯矩区的一些处理方法,并指出了各种方法的优缺点。     

从瞬间到永恒——议伍尔夫《到灯塔去》的时间观

时间概念不但是现代主义文学的重要议题,也反映了科学与哲学理论的演变.伍尔夫在小说《到灯塔去》中呈现了一种二元时间观,即物理时间和心理时间.本文从伍尔夫对传统物理时间概念的背叛出发,认为伍尔夫的时间是通过视觉的瞬间来衡量的,这与印象派画作的技巧不谋而合.这样灵活多变的瞬间可以反映丰富的日常生活,伍尔夫对日常生活的重视与19世纪文学中大叙事、大事件传统背道而驰.伍尔夫认为这样的日常生活恰恰反映了一种真实的,时间的恒常性,一种平衡与失衡的持续状态.     

制动器试验台的控制方法分析

本文利用刚体转动理论结合数学模型建立的思想对制动器试验台的控制方法进行分析。     

Option overlay strategies

Option overlays on a rebalanced portfolio are designed. Inputs to the design problem are the physical and risk neutral probabilities at the option maturity. They are estimated from time series and option data, respectively. The objective for the design is the bid price of a two price economy modelled as a distorted expectation. The design is monotone increasing in the underlier with a delta constraint. The option positioning is implemented on the S&P 500 index, supposedly rebalanced every 21 days with option positions taken 10 days prior to a rebalance date with a maturity near two months. Option overlays are seen to raise performance measures and reduce drawdowns.     

上部无砌体挑梁与砌体开裂原因分析及优化方案

上部无砌体时的挑染,结构计算通常采用简支方案,在其根部与砌体接触面之间易出现裂缝。文章分析了裂经同现的力学原因。并根据力学理论提出了改进办法－采用固端方案。从而大大降低了这类裂缝出现的可能性。     

三段截尾变量小值概率上界的估计

在给定随机变量X∈[-a,M-a],M＞0,a≥0,且EX＝m1,EX2＝m2的条件下,研究了三段线性函数max（0,X,mX-z）的概率分布的上界,其中m＞1,z＞0,M＞max（m1,z/（m-1））。通过简单的变换,将概率问题转化成了均值问题后,应用对偶的理论,构造控制函数,得到了概率分布的上界。是X∈[-a,＋∞],a≥0,且EX＝m1,EX2＝m2,三段线性函数max（0,X,mX-z）的概率分布（左尾）界的推广。具有很强的理论和重要的实际意义。     

Average drawdown risk reduction and risk tolerances

We investigate the effects of average drawdown risk reduction on US mutual funds. Due to numerous evidence of the asymmetric distribution of portfolio returns, the asymmetric risk measures have extensively been used in risk management during the recent decades with extensive usages on the n-degree lower partial moment (LPM) methodology. Unlike the previous literature, we use the n-degree average drawdown risk measure, which is a special case of n-degree LPM, to empirically investigate the impacts of n-degree average drawdown risk reduction on the risk tolerances generated by the US mutual funds.The evidence shows that skewness does not impose any significant problem on the n-degree A-DRM model. Moreover, the effect of changing the tolerances of average drawdown risk in the n-degree A-DRM models is a reduction in the fund returns. The n-degree CA-DRM optimization model reduces investors׳ risk more than other models. Thus, the A-DRM can be accommodated with risk-averse investors׳ approach. The efficient set of mean–variance choices from the investment opportunity set, as described by Markowitz, shows that the n-degree CA-DRM algorithms create this set with lower risk than other algorithms. It implies that the mean–variance opportunity set generated by the n-degree CA-DRM creates lower risk for a given return than covariance and CLPM.     

Value Functions for Prospect Theory Investors: An Empirical Evaluation for U.S. Style Portfolios

The main aim of this article is to provide a general behavioral analysis that proposes a series of different value functions for prospect theory (PT) investors incorporated into behavioral reward-risk models that are finally solved so as to provide some specific optimal solutions. To do this, general behavioral reward-risk models, which contain all the basic elements of the PT, are first set up. Two reward and risk measures, the upper partial moment and the lower partial moment, are subsequently used to create the various value functions. The technical difficulties arising during the behavioral maximization process are overpassed by adapting the Rubinstein [1982 Rubinstein, R. Y. “Generating Random Vectors Uniformly Distributed Inside and On the Surface of Different Regions.” European Journal of Operational Research, 10, (1982), pp. 205–209.[Crossref], [Web of Science ®] , [Google Scholar]] algorithm. The results show that agents differentiate their behavior according to their type of preferences (S-shaped, reverse S-shaped, kinked convex, and kinked concave value function) but they seem to always prefer small capitalization and high positively skewed value stock portfolios. Probability distortion also affects the optimal solutions of the problem, independently of the employing weighting functional form; when subjective probabilities are employed the optimal weights of the most risky positively skewed assets seem to increase. Probability distortion has an additional important effect on optimal perspective values of the problem driving to a significant increase.     

浅析对外汉语教学中的常见时间词

针对时间词的研究,不仅是现代汉语研究的重点,同时也是对外汉语教学的重点和难点。本文主要以对外汉语教学中经常涉及的时间词,如＂年、月、日、星期、小时＂等为研究对象,分析其使用偏误,归纳总结其准确用法。