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Wang K.-H.,Asia University, Taiwan | Yang D.-Y.,Institute of Information and Decision science | Pearn W.L.,National Chiao Tung University
International Journal of Innovative Computing, Information and Control | Year: 2012

We consider a randomized policy to control the M/G/1 queueing system with an unreliable server, second optional service and general startup times. The server is subject to breaking down according to a Poisson process, and the repair time obeys a general distribution. All arrived customers demand the first required service, and only some of the arrived customers demand the second optional service. After all the customers are served in the system, the server immediately takes a vacation and operates the (T, p)-policy. For this queueing system, we employ maximum entropy approach with several constraints to develop the probability distributions of the system size and the expected waiting time in the queue. Based on the accuracy comparison between the exact and approximate methods, we show that the maximum entropy approach is quite accurate for practical purpose, which is a useful method for solving complex queueing systems. © 2012 ISSN 1349-4198.

Wang Y.-F.,Institute of Information and Decision science | Chang M.-Y.,Chang Gung Memorial Hospital | Chiang R.-D.,Tamkang University | Hwang L.-J.,Tamkang University | And 2 more authors.
Journal of Medical Systems | Year: 2013

Ultrasound guided aspiration of ovarian endometrioma had been tried as an alternative therapeutic modality in patients whose desire to avoid surgery or surgical approach is contraindicated since 1991. Cyst puncture can reduce tumor volume and destruct the cyst wall, alleviate sticking circumstances and enhance the chance of recovery. But simple aspiration without other treatments results in high recurrence rate (28.5 % to 100 %). In order to reduce recurrence after aspiration, ultrasound-guided aspiration with instillation of tetracycline, methotrexate, and recombinant interleukin-2 has been combined and proven to be effective with the recurrence rates of 46.9 %, 18.1 %, and 40 % respectively. Noma et al. (2001) reported that conduct of ethanol instillation for more than 10 min particularly for a case with a single endometrial cyst is considered most effective from the standpoint of recurrence (14.9 %). Our goal is to analyze patients with recurrent pelvic cyst who underwent surgical intervention. The research data are based on clinical diagnosis, symptoms and medical intervention classification, and the cyst numbers are defined as forecast project target. The decision tree, methodology of data mining technology, is used to find the meaningful characteristic as well as each other mutually connection. The experimental result can help the clinical faculty doctors to better diagnose and provide treatment reference for future patients. © 2013 Springer Science+Business Media New York.

Wang H.-L.,Institute of Information and Decision science | Chen K.-Y.,National Taiwan University
Theoretical Computer Science | Year: 2014

Given two sets of points, the text and the pattern, determining whether the pattern "appears" in the text is modeled as the point set pattern matching problem. Applications usually ask for not only exact matches between these two sets, but also approximate matches. In this paper, we investigate a one-dimensional approximate point set pattern matching problem proposed in [19]. We generalize the measure between approximate matches from L1-norm to Lp-norm. More specifically, what requested is an optimal match which minimizes the Lp-norm of the difference vector (| p2-p1-(t2′-t1′)|,|p3- p2-(t3′-t2′)|,.,|Pm-pm-1- (tm′-tm-1′)|), where p1,p2,.,Pm is the pattern and t1′,t2′,.,tm′ is a subsequence of the text. For p→∞, we propose an O(mn)-time algorithm, where m and n denote the lengths of the pattern and the text, respectively. For arbitrary p<∞, we propose an algorithm which runs in O(mnT(p)) time, where T(p) is the time of evaluating xp for xεR. © 2013 Elsevier B.V.

Yang D.-Y.,Institute of Information and Decision science | Chang P.-K.,Institute of Information and Decision science
International Journal of Systems Science | Year: 2015

This paper investigates the F-policy queue using fuzzy parameters, in which the arrival rate, service rate, and start-up rate are all fuzzy numbers. The F-policy deals with the control of arrivals in a queueing system, in which the server requires a start-up time before allowing customers to enter. A crisp F-policy queueing system generalised to a fuzzy environment would be widely applicable; therefore, we apply the -cuts approach and Zadeh's extension principle to transform fuzzy F-policy queues into a family of crisp F-policy queues. This study presents a mathematical programming approach applicable to the construction of membership functions for the expected number of customers in the system. Furthermore, we propose an efficient solution procedure to compute the membership function of the expected number of customers in the system under different levels of . Finally, we give an example of the proposed system as applied to a case in the automotive industry to demonstrate its practicality. © 2013 Taylor and Francis.

Yang D.-Y.,Institute of Information and Decision science | Chiang Y.-C.,Institute of Information and Decision science | Tsou C.-S.,Institute of Information and Decision science
Journal of Manufacturing Systems | Year: 2013

This paper analyzes a repairable M/M/1/N queueing system under a threshold-based recovery policy. The threshold-based recovery policy means that the server breaks down only if there is at least one customer in the system, and the recovery can be performed when q (1 ≤ q ≤ N) or more customers are present. For this queueing system, a recursive method is applied to obtain steady-state solutions in neat closed-form expressions. We then develop some important system characteristics, such as the number of customers in the system, the probability that the server is busy, the effective arrival rate and the expected waiting time in the system, etc. A cost model is constructed to determine the optimal threshold value, the optimal system capacity and the optimal service rate at a minimum cost. In order to solve this optimization problem, the direct search method and Newton's method are employed. Sensitivity analysis is also conducted with various system parameters. Finally, we present some managerial insights through an application example. © 2012 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.

Yang J.-S.,Institute of Information and Decision science | Chang J.-M.,Institute of Information and Decision science
Computer Journal | Year: 2014

A set of k spanning trees rooted at the same vertex r in a graph G is called independent [and the trees are called independent spanning trees (ISTs)] if, for any vertex x ≠ r, the k paths from x to r, one path in each tree, are internally disjoint. The design of ISTs on graphs has applications to fault-tolerant broadcasting and secure message distribution in networks. It was conjectured that, for any k-connected graph, there exist k ISTs rooted at any vertex of the graph. The conjecture has been proved true for k-connected graphs with k ≤ 4, and remains open otherwise. In this paper, we deal with the problem of constructing ISTs on the Cartesian product of a sequence of hybrid graphs, including cycles and complete graphs. Consequently, this result generalizes a number of previous works. Moreover, the construction is shown to be optimal in the sense that the heights of ISTs are minimized. © 2012 The Author 2012. Published by Oxford University Press on behalf of The British Computer Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Wu Y.-W.,National Taiwan University | Lin W.-Y.,National Taiwan University | Wang H.-L.,Institute of Information and Decision science | Chao K.-M.,National Taiwan University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

We consider an extension of the popular matching problem: the popular condensation problem. An instance of the popular matching problem consists of a set of applicants A and a set of posts P. Each applicant has a strictly ordered preference list, which is a sequence of posts in order of his/her preference. A matching M mapping from A to P is popular if there is no other matching M′ such that more applicants prefer M′ to M than prefer M to M′. Although some efficient algorithms have been proposed for finding a popular matching, a popular matching may not exist for those instances where the competition of some applicants cannot be resolved. The popular condensation problem is to find a popular matching with the minimum number of applicants whose preferences are neglected, that is, to optimally condense the instance to admit a local popular matching. We show that the problem can be solved in O(n + m) time, where n is the number of applicants and posts, and m is the total length of the preference lists. © 2013 Springer-Verlag.

Yang D.-Y.,Institute of Information and Decision science | Wang K.-H.,Providence University
Journal of Industrial and Production Engineering | Year: 2013

This paper considers two randomized control policies. One is (p, F)-policy queue which deals with the issue of randomized controlling arrivals to a queueing system and the server requires a start-up time before allowing customers to enter the system. Another is (q, N)-policy queue which considers the common issue of controlling service in a queueing system randomly, and the server requires a start-up time before providing service. The steady-state probability distribution of the system size and system performances measures are developed for both queues. In addition, we uncover an interrelationship between the (p, F)- and (q, N)-policy M/M/1/K queues by a series of propositions. The advantage created through interrelationship is that the solution of one queue has been derived, which assists us in obtaining that of the other queue easily. Finally, numerical results are presented for illustration purposes. © 2013 Chinese Institute of Industrial Engineers.

Wu R.-Y.,Lunghwa University of Science and Technology | Chang J.-M.,Institute of Information and Decision science | Chang C.-H.,Lunghwa University of Science and Technology
Mathematical and Computer Modelling | Year: 2011

Ordered trees are called non-regular trees with a prescribed branching sequence (or non-regular trees for short) if their internal nodes have a pre-specified degree sequence in preorder list. This article presents two main results. First, we develop a simple algorithm to generate all non-regular trees in lexicographic order using RD-sequences defined by [R.-Y. Wu, J.-M. Chang, Y.-L. Wang, Loopless generation of non-regular trees with a prescribed branching sequence, The Computer Journal 53 (2010) 661-666]. Then, by analyzing the structure of a coding tree, this algorithm is proved to run in constant amortized time. Next, we propose efficient ranking algorithm (i.e., determining the rank of a given non-regular tree in such an order) and unranking algorithm (i.e., converting a positive integer to its corresponding RD-sequence). © 2010 Elsevier Ltd.

Yang D.-Y.,Institute of Information and Decision science | Wu Y.-Y.,Institute of Information and Decision science
Lecture Notes in Engineering and Computer Science | Year: 2014

This study considers the M/M/1/N queue with working breakdowns and server vacations. We assume that the arrivals occur according to a Poisson process. The server is subject to breakdowns and repairs while in operation. At failure times, the server still works at a lower service rate rather than completely stopping service. When there are no customers in the system, the server takes multiple vacations. Service, repair, and vacation times are exponentially distributed. We apply the Markov process theory to present the differential-difference equations of the queueing system. A numerical technique based on the fourth-order Runge-Kutta method is used to compute the transient state probabilities. Using the transient solutions, we develop some system performance measures, such as the time-dependent expected number of customers in the system, the time-dependent expected waiting time in the system, etc. Finally, a sensitivity analysis is performed to assess the effects of various parameters on the performance measures of the system through numerical results.

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