Approximation of the Bivariate Renewal Function

Recently, Kambo and his co-researchers (2012) proposed a method of approximation for evaluating the one-dimensional renewal function based on the first three moments. Their method is simple and elegant, which gives exact values for well-known distributions. In this article, we propose an analogous method for the evaluation of bivariate renewal function based on the first two moments of the variables and their joint moment. The proposed method yields exact results for certain widely used bivariate distributions like bivariate exponential distribution, bivariate Weibull distributions, and bivariate Pareto distributions. An illustrative example in the form of a two-dimensional warranty problem is considered and comparisons of our method are made with the results of other models.     

股票指数期货与股票保值

本文介绍了股票指数期货的产生与发展，详细叙述了美国、香港等地指数期货合约规格及结算方式，并介绍了怎样利用市场趋势对股票进行套期保值。     

西方企业战略更新研究

企业战略更新是21世纪战略管理学的重要主题之一。阅读大量文献后,发现西方学者从不同的角度研究战略更新问题。美国学者佛罗达等是从中层管理者的角度出发,认为中层管理者是探索战略更新的一个合适的切入点。荷兰学者沃伯达等从共同演进的视角思考了战略更新,认为战略更新是一个持续的过程,应该把环境的选择和管理的适应性相结合。荷兰学者温勒梅科等是从整合的视角探索战略更新的轨迹,他们的研究视野融入了三个维度:组织形式、管理者角色和时间维度。     

经济转轨期农村经营模式:路径、绩效与创新

目前,我国农村实行的是以家庭承包经营为基础的双层经营体制。这种体制的弊端在于土地难以流转、经营规模太小、市场联系面窄、抵抗风险能力弱、农业资本投资不足、土地使用效率低等。要进一步发展农村经济,就必须创新经营模式,下一步应该把突破口放在以产权清晰为基础的统一经营上,建立农村家庭、涉农企业、集体和政府利益协同的产业链,把重点放在农产品的加工和流通环节,以企业为龙头,建立大市场大流通,实现规模经济效应。     

同种商品不同月份期货组合风险评价模型研究及应用

以期货合约的每一交易日的对数涨跌率来反映市场风险,借助VaR风险价值法,运用加权核估计技术(WKDE)和指数加权滑动模型(EWMA),建立了基于期货组合中持有头寸不同且可以进行风险对冲的期货组合市场风险非线性叠加评价模型,解决了同种商品、不同月份期货组合每一交易日最大损失的确定问题,并通过实证研究验证了模型的实用性.该模型的特点一是借助WKDE法预测组合中单个合约每一交易日涨跌率最大日亏损值,充分体现了期货合约涨跌率的实际走势,使VaR估计更加精确.二是通过动态迁移相关系数矩阵的计算保证了模型的精确性.采用EWMA模型预测动态变化的方差-协方差矩阵,从实证的角度得到更精准的动态迁移相关系数矩阵.三是考虑了组合中多头和空头不同头寸之间的风险对冲,避免了实际中期货组合风险的线性相加而造成放大风险或减少风险的不准确性,从而能较好地保证了模型的预测精度及准确性.四是通过基于风险非线性叠加建立的期货组合风险评价模型解决了SPAN系统中期货组合风险的线性叠加问题,从而得到更合理的组合风险预测值.     

Elementary renewal theorems for widely dependent random variables with applications to precise large deviations

Abstract

On the basis of Wang and Cheng (J. Math. Anal. Appl. 384 (2011) 597–606), this paper further investigates elementary renewal theorems for counting processes generated by random walks with widely orthant dependent increments. The obtained results improve the corresponding ones of the above-mentioned paper mainly in the sense of weakening the moment conditions on the positive parts of the increments. Meanwhile, a revised version of strong law of large numbers for random walks with widely orthant dependent increments is established, which improves Theorem 1.4 of Wang and Cheng (2011 Wang, Y., and D. Cheng. 2011. Basic renewal theorems for a random walk with widely dependent increments and their applications. Journal of Mathematical Analysis and Applications 384 (2):597–606. doi:10.1016/j.jmaa.2011.06.010.[Crossref], [Web of Science ®] , [Google Scholar]) by enlarging the regions of dominating coefficients. Finally, by using the above results, some precise large deviation results for a nonstandard renewal risk model are established, in which the innovations are widely orthant dependent random variables with common heavy tails, and the inter-arrival times are also widely orthant dependent.     

城市更新背景下的文化旅游发展研究——以广州为例

文化旅游的兴起是当今旅游业发展的一大趋势。城市更新是城市发展的一种重要途径。随着文化消费时代的来临、文化经济的快速发展,文化旅游在城市更新发展中扮演着日益重要的角色。本文主要以广州为例,探讨了城市更新背景下文化旅游发展的意义、面临的问题和挑战以及进一步的思考。     

How publics react to situational and renewing organizational responses across crises: Examining SCCT and DOR in social-mediated crises

The prevalence of social media among networked publics calls for more research regarding how organizations can conduct effective crisis communication on social networking sites. Based on the situational crisis communication theory (SCCT) and the discourse of renewal (DOR) theory, this study examined how social media publics’ sentiments were affected by situational and renewing organizational responses in various clusters of crises. Twitter data of six crises representing three crisis clusters varying in the responsibility attribution (i.e., ambiguous, accidental, and preventable) were collected. We conducted a content analysis on organizations’ official tweets during crises (N = 59) and sentiment analysis on publics’ replies on Twitter (N = 4,340). The results showed that publics’ positive sentiments toward organizations were affected by organizational crisis responses that included instructing information, sympathy, systemic organizational learning, and effective organizational rhetoric. We recommend that crisis managers express sympathy toward publics as well as organizational learning that prevents a crisis from happening again.     

The covariance of the backward and forward recurrence times in a renewal process: the stationary case and asymptotics for the ordinary case

In a Poisson process, it is well-known that the forward and backward recurrence times at a given time point t are independent random variables. In a renewal process, although the joint distribution of these quantities is known (asymptotically), it seems that very few results regarding their covariance function exist. In the present paper, we study this covariance and, in particular, we state both necessary and sufficient conditions for it to be positive, zero or negative in terms of reliability classifications and the coefficient of variation of the underlying inter-renewal and the associated equilibrium distribution. Our results apply either for an ordinary renewal process in the steady state or for a stationary process.     

英语学术论文中的遁言研究

学术论文写作并非是不受作者主观影响的就事论事的客观陈述,成功的学术英语写作需要借助遁言运用以达到特定的交际目的.对遁言的运用和分布的研究结果表明:遁言是学术语篇社团成员广泛使用的一种修辞手段,学术英语中的遁言现象不仅是作者、读者、语篇三者交互的结果,也是用语言形式体现作者心理取向的产物,是一种认知情态.遁言研究对学术英语具有重要意义.