Mathematical model and heuristics for maximizing reliability of parallel systems with alternatives and budget constraints

Reliability is defined as the ability to perform a given function over a period of time in a particular environment. Designing problem of the system structure appears in many industries, and various reliability optimization issues arise. Especially in military defence area, it is very important to achieve maximum reliability under a given budget. In this study, maximum reliability optimization problem in parallel system, each component has several alternatives, and limited budget reliability optimization problem is considered. Objective function of the problem is expressed as a nonlinear function because it is a reliability of a parallel system. Therefore, it is generally known as difficult to obtain a global optimal solution. In this paper, we propose a heuristic methodology that solves the problem by using Combinatorial Bender's Cut. The results of experiments proved that the proposed algorithm showed good performance in terms of value of the obtained reliability and consumed CPU time. Keywords : parallel system, reliability, nonlinear programming, heuristic DOI: 10.7176/IEL/10-2-07 Publication date:April 30th 202

Monte Carlo simulation-based defect ratio estimation approach for a chemical materials stockpile reliability program

A chemical material stockpile reliability program (CSRP) that determines the usability, safety, reliability, and performance of chemical equipment and materials is developed to determine the storage or disposal of chemical material stockpile (Storage Chemical Equipment and Material Reliability Evaluation Instruction, 2019). However, current inspection for current CSRP depend on test and evaluation of criteria for level of importance, and so the number of samples and acceptance quality limit (AQL) are presented based on the lot size. All the processes are conducted under KS Q ISO 2859-1, and the defect rate of the entire lot of CSRP items is generally assumed to be a distribution that is similar to a binomial distribution. However, the pass-fail test for CSRP items is based on approximately 10 test items, and the factors that cause defects in these items are also heterogeneous. We propose a new methodology for estimating the defect rates of CSRP items based on Monte Carlo simulations, which are widely used in various academic fields. In addition, we show the future applicability of the methodology by applying it to the K1 gas mask case and revealing the results of the defect rate estimation. We also present future work, including the need for a standard sample of CSRP items

Monte Carlo simulation-based defect ratio estimation approach for a chemical materials stockpile reliability program

A chemical material stockpile reliability program (CSRP) that determines the usability, safety, reliability, and performance of chemical equipment and materials is developed to determine the storage or disposal of chemical material stockpile (Storage Chemical Equipment and Material Reliability Evaluation Instruction, 2019). However, current inspection for current CSRP depend on test and evaluation of criteria for level of importance, and so the number of samples and acceptance quality limit (AQL) are presented based on the lot size. All the processes are conducted under KS Q ISO 2859-1, and the defect rate of the entire lot of CSRP items is generally assumed to be a distribution that is similar to a binomial distribution. However, the pass-fail test for CSRP items is based on approximately 10 test items, and the factors that cause defects in these items are also heterogeneous. We propose a new methodology for estimating the defect rates of CSRP items based on Monte Carlo simulations, which are widely used in various academic fields. In addition, we show the future applicability of the methodology by applying it to the K1 gas mask case and revealing the results of the defect rate estimation. We also present future work, including the need for a standard sample of CSRP items

Binary linear programming models for robust broadcasting in communication networks : [data]

Output files showing optimal network configurations. Abstract from related article: Broadcasting is an information dissemination process in communication networks whereby a message, originated at any node of a network, is transmitted to all other nodes of the network. In c-broadcasting, each node having the message completes up to c transmissions to its neighbors over the communication lines in one time unit. In a k-fault tolerant broadcast network, the broadcasting process can be accomplished even if k communication lines fail. This paper presents innovative binary linear programming formulations to construct c-broadcast graphs, k-fault-tolerant broadcast graphs, and their time-relaxed versions. The proposed mathematical models are used to generate eight previously unknown minimum c-broadcast graphs, new upper bounds for eleven other instances of the c-broadcast problem, and over 30 minimum k-fault-tolerant c-broadcast graphs. The paper also provides a construction method to produce an upper bound for an infinite family of k-fault-tolerant c-broadcast graphs

Simvastatin plus irinotecan, 5-fluorouracil, and leucovorin (FOLFIRI) as first-line chemotherapy in metastatic colorectal patients: a multicenter phase II study

BACKGROUND: Simvastatin has demonstrated anti-tumor activity in preclinical studies via tumor cell senescence, anti-angiogenesis, and apoptosis. This phase II trial evaluated the efficacy and toxicity profile of conventional FOLFIRI chemotherapy plus simvastatin in metastatic colorectal cancer patients. METHODS: Patients received irinotecan 180 mg/m(2) as a 90-min infusion followed by leucovorin 200 mg/m(2) in a 2-h infusion, and then 5-FU 400 mg/m(2) bolus injection followed by 2,400 mg/m(2) as a 46-h continuous infusion. Treatment cycles were repeated every 2 weeks until documented disease progression, unacceptable toxicity, or patient's refusal. Simvastatin 40 mg tablet was given once daily per oral everyday during the period of chemotherapy without a rest. RESULTS: From October 2005 to June 2006, 49 patients were enrolled. The overall response rate (ORR) was 46.9% (95% CI, 31.0-58.8) by intent-to-treat analysis and 45.8% (95% CI, 33.3-62.8) by per-protocol analysis. There were one complete response (CR) and 22 partial responses (PRs). Both CR and PRs were confirmed at least 4 weeks later. The disease-control rate was 83.7% (95% CI, 73.4-94.0). The median follow-up duration was 25.6 months (range, 20.9-28.8 months). The median survival of all patients was 21.8 months (95% CI, 14.4, 29.2). The median TTP was 9.9 months (95% CI, 6.4, 13.3). No patients experienced additional adverse effect that was definitely caused by simvastatin drug therapy in this trial. CONCLUSION: The combination of simvastatin plus FOLFIRI was a feasible regimen with promising antitumor activity