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.     

交流电路参数的实用测量法研究

探讨了二端交流电路的R,L,C元件参数的测定,并研究了工频电路的等效电阻、等效电抗的测量方法。     

5次交错群A_5的10阶子群的一个构造方法

A5的元最大阶数是5,使用有限群的Lagrange定理,A5的10阶子群元的阶只可能是2,5。但由于拉格朗日定理的逆不成立,因此是否存在A5的10阶子群仍是问题。该文通过对5-循环置换各次方幂的计算及其研究,找到A5的10阶子群元的构成规律,并使用构造性方法给出了5次交错群A5的6个10阶子群。     

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。     

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。     

Bayesian prediction of waiting times in stochastic models

The authors show how saddlepoint techniques lead to highly accurate approximations for Bayesian predictive densities and cumulative distribution functions in stochastic model settings where the prior is tractable, but not necessarily the likelihood or the predictand distribution. They consider more specifically models involving predictions associated with waiting times for semi‐Markov processes whose distributions are indexed by an unknown parameter θ. Bayesian prediction for such processes when they are not stationary is also addressed and the inverse‐Gaussian based saddlepoint approximation of Wood, Booth & Butler (1993) is shown to accurately deal with the nonstationarity whereas the normal‐based Lugannani & Rice (1980) approximation cannot, Their methods are illustrated by predicting various waiting times associated with M/M/q and M/G/1 queues. They also discuss modifications to the matrix renewal theory needed for computing the moment generating functions that are used in the saddlepoint methods.     

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.     

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.