Water cycle algorithm for solving the reliability-redundancy allocation problem with a choice of redundancy strategies

Abstract

This paper proposes a new mathematical model for the reliability-redundancy allocation problem (RRAP) with a choice of redundancy strategies. To maximize the reliability of a system, this model chooses the best redundancy strategy from among both active and standby ones for each subsystem. For those with a standby strategy, a continuous time Markov chain model is used to calculate the exact reliability values. In order to solve the proposed mixed-integer non-linear programing model, a powerful evolutionary algorithm, called water cycle algorithm (WCA), is developed and implemented on three famous benchmark problems. Finally, the results of different benchmark problems are compared with those previously reported to show the superiority of the proposed model and the efficiency of WCA.     

《儒林外史》的"三复情节"及其意义

《儒林外史》研究向来较少注意到它与《三国演义》《水浒传》等前代小说传统的联系,其实此书暗用“三顾茅庐”之类“三复情节”模式不止一端,其用笔隐微几于使人不觉,而作品的讽刺意义因而更为深广,如马二先生游西湖是从“食色,性也”角度写他内心理欲之争等。这既是前代小说“三复情节”模式的影响,更是古代礼数观念和社会上“事不过三”等重“三”的风习潜移默化的结果。这一发现使中国古代小说“三复情节”模式的普遍性获得新的证明,也使“三复情节”概念对于中国古代小说研究的理论意义得到加强。这对于总结中国古代小说艺术的民族特点以及建立有中国特色的关于中国古代文学的理论也应当能有所帮助。     

Combining forecasts of electricity consumption in China with time-varying weights updated by a high-order Markov chain model

Electricity consumption forecasting has been always playing a vital role in power system management and planning. Inaccurate prediction may cause wastes of scarce energy resource or electricity shortages. However, forecasting electricity consumption has proven to be a challenging task due to various unstable factors. Especially, China is undergoing a period of economic transition, which highlights this difficulty. This paper proposes a time-varying-weight combining method, i.e. High-order Markov chain based Time-varying Weighted Average (HM-TWA) method to predict the monthly electricity consumption in China. HM-TWA first calculates the in-sample time-varying combining weights by quadratic programming for the individual forecasts. Then it predicts the out-of-sample time-varying adaptive weights through extrapolating these in-sample weights using a high-order Markov chain model. Finally, the combined forecasts can be obtained. In addition, to ensure that the sample data have the same properties as the required forecasts, a reasonable multi-step-ahead forecasting scheme is designed for HM-TWA. The out-of-sample forecasting performance evaluation shows that HM-TWA outperforms the component models and traditional combining methods, and its effectiveness is further verified by comparing it with some other existing models.     

简论改革浪潮中的文化建设

在新时期的改革浪潮中，社会主义文化建设随着时代的变化取得了辉煌的成就。文化建设尤其是在根本任务的发展、主要内容的丰富、基本取向及建设方针的演进等方面都体现出与新时期相适应的变化。     

Fire Risks in Oil Refineries: Economic Analysis of Camera Monitoring

A probabilistic method is presented to evaluate the economic value of fire monitoring by closed circuit TV camera in petroleum refineries. The proposed model is restricted to the analysis of risk reduction in an area where fires can be caused either by pump failure or by failure of valves and lines. The benefits come from reducing the time during which the fire grows undetected. Fire growth and expected values of losses are analyzed by a Markov model that includes five phases: (1) active undetected growth, (2) detection, (3) fire growth at the beginning of the firemen's intervention, (4) fire control, and (5) fire extinction. The results (e.g., the expected net present value of the investment) show that the proposed monitoring investment is attractive for an illustrative example.     

Dependence Estimation Over a Finite Bivariate Failure Time Region

This articleconcerns nonparametric estimation of association between bivariatefailure times. In the presence of independent right censoring,the support for failure time variates may be restricted and measuresof dependence over a finite failure time region may be of particularinterest. To this end, the reciprocal cross ratio function, weightedby the bivariate failure time density, is proposed as a summarymeasure of dependence over a failure time region. This `relativerisk' estimator is shown to be consistent and asymptoticallynormally distributed, with consistent bootstrap variance estimator.A finite-region version of Kendall's tau, which is suitable forcensored failure time data, is also proposed, and correspondingasymptotic distribution theory is noted. The accuracy of theseasymptotic approximations is studied in simulations and an illustrationis provided.     

代理证券相对有效性

分析了具有特定的期望收益率向量R与风险因子向量β截面关系的代理证券组合边界,进而研究了代理证券组合边界与有效证券组合边界的差异以及代理证券相对有效度。     

Hypothesis Testing of Hazard Ratio Parameters in Marginal Models for Multivariate Failure Time Data

Marginal hazard models for multivariate failure time data have been studied extensively in recent literature. However, standard hypothesis test statistics based on the likelihood method are not exactly appropriate for this kind of model. In this paper, extensions of the three commonly used likelihood hypothesis test statistics are discussed. Generalized Wald, generalized score and generalized likelihood ratio tests for hazard ratio parameters in a marginal hazard model for multivariate failure time data are proposed and their asymptotic distributions examined. The finite sample properties of these statistics are studied through simulations. The proposed method is applied to data from Busselton Population Health Surveys.     

ODE法在多目标规划中的应用

在一定条件下,从多目标规划问题的任一可行解的某邻域出发,建立了沿着所建立的常微分方程组的轨线,关于部分交元总收敛到原多目标规划问题的(弱)有效解。     

模式解构的极致与限度--论新历史小说对民国时代的叙述

西方当代史学观念的介绍与引进、历史行程的延展性与几度的迂回性、作家自身的独特经历促使新一代作家抛弃既有历史观、文学观,完全颠覆民国叙事的经典模式打破阶级界线、释放个人欲望、强调偶然不测,并用种种形式探索来显示历史叙述的主观性,创作了一批被称为"新历史小说"的作品.但解构的偏执,使他们的历史言说局限于"前文本"的固有层次,最终未能表达出对民国时代的个性化理解.