摘要:

AbstractLet Xibe independent IFR random variables and let Yibe independent exponential random variables such that E[Xi]=E[Yi] for all i=1, 2, ⃛ n. Then it is well known that E[min (Xi)] ≥E[min (Xi)]. Nevertheless, for 1≤i≤n exponentially distributed Xi's and for a decreasing convex function ϕ(.). it is shown that\documentclass{article}\pagestyle{empty}\begin{document}$$ E[\Phi (\mathop {\min }\limits_{1\le i\le n}\,(X_i))]\,\, \le\,\,E[\Phi (\mathop {\min}\limits_{1\le i \le n} \,(X_i))] $$\end{d

ISSN:0028-1441    

DOI:10.1002/nav.3800290302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractAn availability measure is the probability that a two‐state system modeled by an alternating renewal process is available at one or more points or intervals. The concept of availability measures is extended to formulae for the joint prediction of availability and numbers of breakdowns (or repairs) of the system during a fixed interva

ISSN:0028-1441    

DOI:10.1002/nav.3800290303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractWe compare several competing estimates of the availability of a system which alternates between two states, “up” and “down,” in accordance with an alternating renewal process. Both interval and point estimators are compared under several special but representative situations. The comparison reaffirms the validity and robustness of the log‐logistic jackknifed estimates. However, when the point estimates are compared from the intrinsic criterion of probability of concentration, the uniformly minimum variance estimate obtained for the Markov model performs

ISSN:0028-1441    

DOI:10.1002/nav.3800290304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIn this paper we consider a simple three‐order‐statistic asymptotically unbiased estimator of the Weibull shape parametercfor the case in which all three parameters are unknown. Optimal quantiles that minimize the asymptotic variance of this estimator, c̃ are determined and shown to dependonlyon the true (unknown) shape parameter valuecand in a rather insensitive way. Monte Carlo studies further verified that, in practice where the true shape parametercis unknown, using always c̃ with the optimal quantities that correspond toc= 2.0 produces estimates, c̃, remarkably close to the theoretical optimal. A second stage estimation procedure, namely recalculating c̃ based on the optimal quantiles corresponding to c̃, was not worth the additional effort. Benchmark simulation comparisons were also made with the best percentile estimator of Zanakis [20] and with a new estimator of Wyckoff, Bain and Engelhardt [18], one that appears to be the best of proposed closed‐form estimators but usesallsample observations.The proposed estimator, c̃, should be of interest to practitioners having limited resources and to researchers as a starting point for more accurate iterative estimation procedures. Its form is independent of all three Weibull parameters and, for not too large sample sizes, it requires the first, last and only one other (early) ordered observation. Practical guidelines are provided for choosing the best anticipated estimator of shape for a three‐parameter Weibull distribution under different

ISSN:0028-1441    

DOI:10.1002/nav.3800290305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractMust Newton‐type methods for linearly constrained optimization be either of the modified Newton or quasi‐Newton variety? The contention of this paper is that explicity recomputing part of the projected Hessian may be superior to both approaches. A computational comparison with MINOS is presen

ISSN:0028-1441    

DOI:10.1002/nav.3800290306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIn this paper, we develop efficient interactive methods for the solution of bicriteria nonlinear programming problems. The methods do not require trade‐off information from the decision maker, pose less cognitive burden and converge to the “best compromise solution” fast. Two methods, called the paired comparison method and comparative trade‐off method, are presented with examples. A real application of the interactive method to a bicriteria problem that arose in the planning of the cardiovascular disease control program in the U.S. Air Force is also pr

ISSN:0028-1441    

DOI:10.1002/nav.3800290307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThere are a great number of queueing systems, including the MX/MY/c, the GlX/M/c and the discrete Gl/G/1 queue in which the state probabilities are determined by repeated queue equations. This paper gives a simple, efficient and numerically stable algorithm to caiculate the state probabilities and measure of performance for such systems. The method avoids both complex arithmetric and matrix manipulations.

ISSN:0028-1441    

DOI:10.1002/nav.3800290308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper examines the process by which a user of a queueing system selects his arrival time to the system to compensate for unpredictable delays in the system if he wishes to complete service at a particular time. Considering the case in which all the system users have already decided on their arrival times to the system and will not change these times, this paper investigates how a new user of this system develops his strategy for selecting his arrival time. The distribution of this customer's arrival time is then obtained for a special case.

ISSN:0028-1441    

DOI:10.1002/nav.3800290309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper develops a forward algorithm and planning horizon procedures for an important machine replacement model where it is assumed that the technological environment is improving over time and that the machine‐in‐use can be replaced by any of the several different kinds of machines available at that time. The set of replacement alternatives may include (i) new machines with different types of technologies such as labor‐ and capital‐ intensive, (ii) used machines, (iii) repairs and/or improvements which affect the performance characteristics of the existing machine, and so forth.The forward dynamic programming algorithm in the paper can be used to solve a finite horizon problem. The planning horizon results give a procedure to identify the forecast horizonTsuch that the optimal replacement decision for the first machine based on the forecast of machine technology until periodTremains optimal for any problem with horizon longer thanTand, for that matter, for the infinite horizon problem. A flow chart and a numerical example have been included to illustrate the al

ISSN:0028-1441    

DOI:10.1002/nav.3800290310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper deals with flowshop/sum of completion times scheduling problems, working under a “no‐idle” or a “no‐wait” constraint, the former prescribes for the machines to work continuously without idle intervals and the latter for the jobs to be processed continuously without waiting times between consecutive machines. Under either of the constraints the problem is unary NP‐Complete for two machines. We prove some properties of the optimal schedule forn/2/F, no‐idle/σCi. Forn/m/P, no‐idle/σCi, andn/m/P, no‐wait/σCi, with an increasing or decreasing series of dominating machines, we prove theorems that are the basis for polynomial bounded algorithms. All theorems are de

ISSN:0028-1441    

DOI:10.1002/nav.3800290311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY