Journal of the Operations Research Society of Japan
Online ISSN : 2188-8299
Print ISSN : 0453-4514
ISSN-L : 0453-4514
Volume 41, Issue 2
Displaying 1-16 of 16 articles from this issue
  • Article type: Cover
    1998 Volume 41 Issue 2 Pages Cover4-
    Published: 1998
    Released on J-STAGE: June 27, 2017
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  • Article type: Appendix
    1998 Volume 41 Issue 2 Pages App3-
    Published: 1998
    Released on J-STAGE: June 27, 2017
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  • Edmond J. Vanderperre
    Article type: Article
    1998 Volume 41 Issue 2 Pages 171-180
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    We analyse the reliability of Gaver's parallel system sustained by a cold standby unit and attended by two identical repairmen. The system satisfies the usual conditions (i.i.d. random variables, perfect repair, instantaneous and perfect switch, queueing). Each operative unit has a constant failure rate but a general repair time distribution. Our reliability analysis is based on a time dependent version of the supplementary variable method. We transform the basic equation into an integro-differential equation of the (mixed) Fredholm type. The equation generalizes Takacs' integro-differential equation. In order to present computational results, we outline the solution procedure for a repair time distribution with an arbitrary rational Laplace-Stieltjes transform. A particular numerical example displays the survivor function with the security interval that ensures a reliability level of at least 95%.
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  • Tatsuo Matsutomi, Hiroaki Ishii
    Article type: Article
    1998 Volume 41 Issue 2 Pages 181-195
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    In this paper a single facility location problem for an ambulance service station in a polygonal area X is considered. Our objective is to locate an ambulance service station so as to minimize the maximum distance of the route which passes from the facility to the hospital by way of the scene of accident. In this paper, we consider A-distance which is a generalization of rectilinear distance and was introduced by Widmayer et al. Assuming m hospitals at the points H_1, H_2,・・・, H_m and denoting the nearest hospital to a point Q of X with S(Q), the following problem P_M is considered. [numerical formula] where P^* = (x^*,y^*) is the location of an ambulance service station to be determined. Then we show P_M can be reduced to the messenger boy problem with A-distance. Utilizing this result, we propose an efficient solution procedure by extending Elzinga & Hearn Algorithm to A-distance case.
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  • Toshihisa Ozawa, Takuya Asaka
    Article type: Article
    1998 Volume 41 Issue 2 Pages 196-213
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    We consider a dynamic assignment queueing model with multiple packet classes, which has a number of queues, each with its own server. This model arises from the output buffer control of an ATM-based packet switching system, which is connected to another system via multiple links. Each packet is divided into cells and transmitted by cell-by-cell transmission through the links. Such packet arrival processes can be modeled as Poisson cluster arrival processes. An arriving packet is assigned to one of the queues according to a dynamic packet assignment scheme, which is a variation of the shortest queue policy and tries to assign buffer space and/or transmission bandwidth fairly to each class when the system is congested. We derive an approximation of the packet loss probability by using a decomposition method and an asymptotic of the cell loss probability. Its accuracy is examined in comparison with simulation results. The results of this paper can be used for dimensioning the buffer sizes of the ATM-based packet switching systems.
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  • Hiroyuki Tamura, Satoru Takahashi, Itsuo Hatono, Motohide Umano
    Article type: Article
    1998 Volume 41 Issue 2 Pages 214-228
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    In this paper we propose a descriptive extension of a conventional AHP, called D-AHP, such that the rank reversal phenomena is legitimately observed and explanatory. In general, the main causes of rank reversal are violation of transitivity and/or change in decision making structure. In AHP these causes correspond to inconsistency in pairwise comparison and change in hierarchical structure, respectively. Without these causes, AHP should not lead to rank reversal. But if we use inappropriate normalization procedure such that the entries sum to 1, the method will lead to rank reversal even when the rank should be preserved. Concerned with normalization procedure of importance of alternatives with respect to each criterion, we propose to add a hypothetical alternative such that it gives aspiration level for each criterion, and the scale is determined to normalize the eigenvectors so that the entry for this hypothetical alternative is equal to 1 rather than the entries summing up to 1. The relative importance of each criterion is evaluated as follows: If the average importance of all alternatives in the set is far from 1 under a criterion, the weighting coefficient for this criterion is increased. Furthermore, the criterion which gives larger consistency index can be regarded that the decision maker's preference is fuzzy under this criterion. Thus, the importance for such criterion is assigned to be relatively lower. Some numerical examples obtained by D-AHP are included which could explain the legitimacy of rank reversal.
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  • Norio Hibiki
    Article type: Article
    1998 Volume 41 Issue 2 Pages 229-245
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    The cross-efficiency measure in DEA can be used as another way of addressing the issue of efficiency, such as characterizing DMUs and ordering efficient DMUs. In this paper, a theoretical framework to use the cross-efficiency measure properly for evaluating DMUs is discussed and many useful techniques are proposed. First, a new efficiency measure for cross-evaluation, called a modified cross-efficiency (MCE), is proposed in order to solve both arbitrariness and inequality problems related to the cross-efficiency. The MCE is defined as one efficiency score in the range, decided uniquely and fairly by using an appropriate criterion, after minimum and maximum values of cross-efficiencies are computed. Second, seven ways of setting criteria to decide a specific and a unique value are shown, such as (a) a minimum and a maximum value, (b) a satisfaction and an adjusted satisfaction value which degrees of DMUs are equally achieved, (c) a value computed using an average of multipliers as vertices of DEA solutions, (d) an arithmetic and a geometric mean. Moreover, seven techniques to evaluate DMUs using the MCE are shown, such as (a) an arithmetic, a geometric, and a conditional weighted mean of specific (uniquely decided) MCE, (b) a satisfaction and an adjusted satisfaction value which degrees of DMUs are equally achieved, (c) a minimum and a maximum value. The characteristics of the MCE is discussed with numerical examples. Moreover, seven criteria to decide a unique score, and seven evaluation techniques are compared and discussed with the same examples. Various criteria and techniques related to the MCE and the numerical results can help to evaluate DMUs appropriately in the sense of cross-evaluation.
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  • Koji Iida, Ryusuke Hohzaki, Kenji Inada
    Article type: Article
    1998 Volume 41 Issue 2 Pages 246-260
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    In this paper, an optimal search-and-rescue operation maximizing the expected reward for a survivor with a conditionally deterministic motion and with a random lifetime is investigated. Necessary conditions for the optimal distribution of the searching effort and the optimal stopping time of the search are derived and the meaning of the conditions for the optimal plan are elucidated. To show the properties of the optimal search plan, several numerical examples are presented and special cases and generalization of the model are also discussed.
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  • Hiroyuki Nagasawa, Chue Shing
    Article type: Article
    1998 Volume 41 Issue 2 Pages 261-278
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    Stochastic two-objective scheduling to minimize both the expected value and the variance of total flow time is one of the most interesting subjects for shop-floor managers. This paper develops a heuristic method for generating a set of nondominated schedules to this two-objective scheduling problem in a parallel machine case, on the basis of the heuristic method proposed for a single machine case by Jung et al.(1990). Introducing some new categories of the set of nondominated schedules, this paper proposes an interactive system (ISMSS) for selecting a preferred schedule from among the set of nondominated schedules.
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  • Ali Asghar Anvary Rostamy, Yoshio Tabata
    Article type: Article
    1998 Volume 41 Issue 2 Pages 279-288
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    There are several difficulties with GP. This paper is an appraisement to the effectiveness of GP in incorporating DM's preferences and explains some fundamental relationships among the different approaches of incorporating. Since each approach has its own way and properties, we integrate the approaches by a unique classification. We explain why and how inappropriate approximation of nonlinear functions may lead to missing information about DM's preferences and how we can minimize the lost information in GP. Finally, an effective and interactive procedure with a numerical example is suggested in order to help analysts in defining the DM's preference functions more effectively.
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  • Teruaki Hanaoka
    Article type: Article
    1998 Volume 41 Issue 2 Pages 289-310
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    In this paper, a lower bound computation method using energy-state approximation is proposed and applied to supersonic aircraft shortest path problems. The proposed algorithm is basically based on the forward dynamic programming combined with the branch-and-bound technique. This hybrid algorithm can reduce computational requirements and computer memory requirements of the conventional dynamic programming substantially by incorporating the bounding operation of the branch-and-bound into the computing process of the forward dynamic programming. The lower bound of the optimal solution which becomes necessary in execution of the hybrid algorithm is computed by the modified energy-state approximation which can be obtained by modifying partially the conventional energy-state approximation in order to satisfy the lower bound condition. This computation to obtain the lower bound solution is very simple without any difficulties. Also, in this paper, we propose some methods of lower bound reinforcement to obtain a more reduction of computation requirements in the hybrid algorithm. The proposed hybrid algorithm is composed as the acceding to a lot of advantages of dynamic programming and the application to complicated nonlinear systems is easy. At numerical examples to the minimum-time-to-climb problems of the supersonic aircraft, a typical solution obtained by the hybrid algorithm is equivalent to that of the steepest descent method within quantization errors of 0.7%. The number of computation requirements of the hybrid algorithm which is required to obtain optimal solutions is equal to or less than 1.4% at the ratio with the number of computation requirements in the conventional dynamic programming. The computing time is about 60 seconds on a computer with speed of 20 MIPS including 1 second of the computation of the lower bound. Also, when applying this method to the problems to have changed the boundary conditions of the original problem variously to examine the robustness of the hybrid algorithm, the number of computational requirements of the hybrid algorithm was equal to or less than 2% of that to any problems. On the other hand, when using a strengthened lower bound, this number was equal to or less than 1%. Also, we applied the hybrid algorithm to the supersonic aircraft to have changed aerodynamical data variously in order to examine the influence of the change of the aerodynamical data of the supersonic aircraft comprehensively. As a result, that the optimal pass under various conditions could be generated unifyingly without needing skill when using this method was confirmed.
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  • Keyi Wang, Iwaro Takahashi
    Article type: Article
    1998 Volume 41 Issue 2 Pages 311-328
    Published: 1998
    Released on J-STAGE: June 27, 2017
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    It is said that paired comparison is the essence of AHP. But if there are N alternatives and M criteria in a standard AHP, we must compare _MC_2pairs for each criterion and _NC_2 pairs for the set of criteria, and the total number of them becomes up tp _NC_2 × M + _MC_2. So for rather large M and N it takes much cost and time to get paired comparison data. But even if we have not the whole set S_n of _nC_2 pairs (let such a case be called incomplete information case), we can estimate the weights based on comparison data in an appropriate subset of S_n by Harker method or Two-stage method [4, 5]. We can use LLS (logarithmic least square) method in AHP analysis, by which we can analyze AHP for incomplete information case. So we can reduce the number of paired comparisons by using incomplete information case. The problem is how to select pairs to be compared in S_n, that is, a design to get data. We propose the strongly regular (SR) design based on strongly regular graphs, and by numerical simulations how that the errors of the estimations by SR designs are smaller than any random designs for almost all cases. Since SR graphs are rather difficult to be constructed, we generalize them to quasi-strongly regular (quasi-SR) graphs, and propose quasi-SR design based on quasi-SR graphs. By simulation we show that quasi-SR designs also give the same good results as the SR designs.
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  • Article type: Appendix
    1998 Volume 41 Issue 2 Pages 329-331
    Published: 1998
    Released on J-STAGE: June 27, 2017
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  • Article type: Appendix
    1998 Volume 41 Issue 2 Pages App4-
    Published: 1998
    Released on J-STAGE: June 27, 2017
    JOURNAL FREE ACCESS
    Download PDF (76K)
  • Article type: Cover
    1998 Volume 41 Issue 2 Pages Cover5-
    Published: 1998
    Released on J-STAGE: June 27, 2017
    JOURNAL FREE ACCESS
    Download PDF (59K)
  • Article type: Cover
    1998 Volume 41 Issue 2 Pages Cover6-
    Published: 1998
    Released on J-STAGE: June 27, 2017
    JOURNAL FREE ACCESS
    Download PDF (59K)
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