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366 results for “Numerical Study”
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Research ArticleOpen accessIn the abstractDetermining the Optimal Software Rejuvenation Schedule via Semi-Markov Decision ProcessHiroyuki Eto, Tadashi DohiSoftware rejuvenation is a preventive and proactive maintenance policy that is particularly useful for counteracting the phenomenon of software aging. In this study we consider an operational software system with multiple degradations and derive the optimal software rejuvenation policy minimizing the expected operation cost per unit time in the steady state, via the dynamic programming approach. Especially, we show analytically … …Journal of Computer Science, Vol. 2, Issue 6 · 30 Jun 2006 · 6,979 accessesView PDFCite
Research ArticleOpen accessIn the abstractOptimal Rejuvenation Scheduling of Distributed Computation Based on Dynamic ProgrammingHiroyuki Okamura, Kazuki Iwamoto, Tadashi DohiRecently, a complementary approach to handle transient software failures, called software rejuvenation, is becoming popular as a proactive fault management technique in operational software systems. In this study, we develop the optimal scheduling algorithms to trigger software rejuvenation in distributed computation circumstance. In particular, we focus on two different computation circumstances in terms of detection of failures. Based on the … …Journal of Computer Science, Vol. 2, Issue 6 · 30 Jun 2006 · 6,389 accessesView PDFCite
Research ArticleOpen accessIn the abstractConstrained Probabilistic Lost Sales Inventory System with Normal Distribution and Varying Order CostHala, A. Fergany, Mona, F. EL-WakeelThis study derives the probabilistic lost sales inventory system when the order cost is a function of the order quantity. Our objective is to minimize the expected annual total cost under a restriction on the expected annual holding cost when the lead-time demand follows the normal distribution by using the Lagrangian method. Then a published special case is deduced and … …Journal of Mathematics and Statistics, Vol. 2, Issue 1 · 31 Mar 2006 · 7,198 accessesView PDFCite
Research ArticleOpen accessIn the abstractThe Possibility of Cyclical Behavior in a Class of Dynamic ModelsAnjan MukherjiThe study investigates conditions under which endogenous cyclic behavior may be observed within the context of Predator-Prey (Lotka-Volterra) Models. The analysis also establishes conditions under which such behavior is non-existent and hence establishes conditions for global convergence to the interior equilibrium, whenever it exists. The results are then applied to two diverse sets of economic exercises and shows how the … …American Journal of Applied Sciences, Vol. 2, Issue 13 · 9 Dec 2005 · 7,602 accessesView PDFCite
Research ArticleOpen accessIn the abstractMathematical Model Mathematical Models for the Dynamics of Tuberculosis in Density-dependent Populations: The Case of Internally Displaced Peoples' Camps (IDPCs) in UgandaA. Ssematimba, J. Y.T. Mugisha, L.S. LuboobiMathematical models are formulated to establish the conditions (restrictions) on the size of the area occupied required minimizing and thereafter eradicating tuberculosis. Both numerical and qualitative analyses of the model are done and the effect of variation in the area size and recruitment rate on the different epidemiological groups is investigated. The results of the analysis show that there exists … …Journal of Mathematics and Statistics, Vol. 1, Issue 3 · 30 Sep 2005 · 6,895 accessesView PDFCite
Research ArticleOpen accessIn the abstractPeriodic Review Probabilistic Multi-Item Inventory System with Zero Lead Time under Constraints and Varying Order CostHala A. FerganyThis study treats the probabilistic safety stock n-items inventory system having varying order cost and zero lead-time subject to two linear constraints. The expected total cost is composed of three components: the average purchase cost; the expected order cost and the expected holding cost. The policy variables in this model are the number of periods Nr* and the optimal maximum … …American Journal of Applied Sciences, Vol. 2, Issue 8 · 31 Aug 2005 · 7,634 accessesView PDFCite
Research ArticleOpen accessIn the abstractA New Architecture for Improving Location Management in PCS NetworksHaidar Safa, Samuel PierreThis study proposes a new architecture for improving the location management in PCS networks. The proposed architecture employs several HLRs as opposed to one HLR in the IS-41 and GSM models. Indeed, the new architecture associates with each MU two types of HLRs ; a resident HLR that serves the location areas in which the MU often resides and a … …Journal of Computer Science, Vol. 1, Issue 2 · 30 Jun 2005 · 6,783 accessesView PDFCite
Research ArticleOpen accessIn the abstractHigh Density Groundwater Flow, Major-ion Chemistry and Field Experiments in a Closed Basin: Fuente de Piedra Playa Lake (Spain)Rodríguez-Rodríguez Miguel, Benavente Herrera José, Moral Martos FranciscoThis study presents the results of 10 years of field investigation in Fuente de Piedra Playa Lake located in southern Spain. These field observations along the playa's shore revealed evidence of a forced convective flow and the existence of density interface below the playa basin. An upward flux of groundwater from underlying formations could be a considerable part of its … …American Journal of Environmental Sciences, Vol. 1, Issue 2 · 30 Jun 2005 · 6,310 accessesView PDFCite
Research ArticleOpen accessIn the abstractSolving Linear Programming Problems on the Parallel Virtual Machine EnvironmentJrJung Lyu, Hsing Luh, Ming-Chang LeeThis study developed a parallel algorithm to efficiently solve linear programming models. The proposed algorithm utilizes the Dantzig-Wolfe Decomposition Principle and can be easily implemented in a general distributed computing environment. The analytical performance of the well-known method, including the speedup upper bound and lower bound limits, was derived. Numerical experiments are also provided in order to verify the complexity … …American Journal of Applied Sciences, Vol. 1, Issue 2 · 30 Jun 2004 · 7,841 accessesView PDFCite
Research ArticleOpen accessIn the abstractSome Algorithms to Identify Rational Structures in Stochastic Processes with ExpectationsConcepción González-Concepción, María Candelaria Gil-Fariña, Celina Pestano-GabinoThis research was concerned with the identification of rational models in stochastic processes and we use the Padé-Laurent Approximation to identify a Transfer-Function Model with Expectations. We mention the T-table method and focus in studying the generalised epsilon-algorithm, emphasizing the main role of the statistical significance of their numerical entries. Empirical work is made for non-causal TF models using both … …Journal of Mathematics and Statistics, Vol. 3, Issue 4 · 31 Dec 2007 · 6,754 accessesView PDFCite