An unreliability analysis for k-out-of-n: F system
- Authors: Ibrahim, Yousef , Gunawan, Indra , Khorshidi, Hadi
- Date: 2014
- Type: Text , Conference paper
- Relation: Proceedings of 6th Asia-Pacific International Symposium on Advanced Reliability and Maintenance Modeling (APARM 2014): Advanced Reliability and Maintenance Modeling VI p. 208-215
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System dynamics modeling for multi-state systems
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2015
- Type: Text , Conference paper
- Relation: 25th European Safety and Reliability Conference, ESREL 2015; Zurich, Switzerland; 7th-10th September 2015 p. 925-930
- Full Text: false
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- Description: In this paper, the dynamic behavior of the system reliability is modeled by system dynamics approach. Since the reliability levels of the components and systems changes during functioning periods, this variability should be considered in reliability assessment. System dynamics has been used to simulate the dynamic interactions of the phenomena in different areas such as economics, environment, social, humanity, management, and engineering. In system dynamics, Causal Loop Diagrams (CLDs) and stock and flow structures are employed to both represent the elements and model their interactions in order to predict the future status of the system. Due to the capability of the system dynamics in capturing the dynamic behavior of complex systems, it is used for a dynamic assessment of system reliability. The components in this system are multi-state so that they have more performance levels than failure and working states. A case of a multi-state weighted k-out-of-n system is simulated in this study. Software iThink is used to develop the dynamic model for the case study. The results of the system dynamics approach are compared with the outputs of the dynamic availability assessment by mathematical modeling. In addition, the associated cost of maintenance activities is added in the model. Therefore, different scenarios can be evaluated in terms of cost and reliability with the intention of finding optimal decisions. Finally, a sensitivity analysis has been conducted under various conditions in the simulation model. © 2015 Taylor & Francis Group, London.
A bi-objective dynamic model for multi-state weighted k-out-of-n system reliability
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2015
- Type: Text , Conference paper
- Relation: 25th European Safety and Reliability Conference, ESREL 2015; Zurich, Switzerland; 7th-10th September 2015 p. 2229-2234
- Full Text: false
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- Description: Nowadays, improving system reliability is becoming an important criterion for engineering industries. Many studies have been developed to evaluate the reliability of the systems which is the first step in system improvement. Most of these studies have been done in non-dynamic conditions in which the components have the constant reliability values during functioning periods. However, the components' reliability level varies over time due to both failures and maintenance actions. Therefore, time dimension should be added into system reliability evaluation. In this paper, a dynamic assessment is presented for multi-state weighted k-out-of-n systems. The k-out-of-n system is a popular structure in fault-tolerant systems in which n components work in parallel form with a pre-defined k as a condition. This dynamic assessment considers the reliability variation of the components over finite and discrete time periods. It provides an opportunity to assign decision variables for each functioning period, and analyze the impact of each decision on the whole system reliability. In addition, the income generated during each period is defined as an importance weight of the components. Therefore, the present value of the system is obtained by Universal Generating Function (UGF) and engineering economics' tools. Furthermore, an optimization model is developed to find optimal decisions based on system reliability and cost. Since the system reliability is estimated by money, the expected profit of the system can be as the objective function. As a result, the objective function can maximize system reliability and minimize system cost simultaneously. A Matlab programming is created for a numerical example to illustrate the proposed model. © 2015 Taylor & Francis Group, London.
Investigation on system reliability optimization based on classification of criteria
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2013
- Type: Text , Conference proceedings
- Relation: Industrial Technology (ICIT), 2013 IEEE International Conference, Capetown, SA. 25-28 Feb. 2013 p.1706-1711
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- Description: System reliability optimization has been considered as an area to improve the operational availability of electrical and manufacturing systems. This research area addresses system reliability estimation and mathematical model development. This paper presents a -review on system reliability optimization techniques based on different classification of criteria. The main criteria considered in this study are system structure, system state, optimization model, allocation model, modeling and solution methods. The classification can provide an overview of all criteria that should be used to make optimal decisions in a system by taking the reliability into account. Not only it can assist the researchers to develop new optimization models, but also it presents the practitioners how system reliability optimization models can help industries. The paper also discusses the limitations of the present techniques in this area.
Financial view and profitability evaluation on multistate weighted k-out-of-n:F system reliability
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal of Reliability and Safety Vol. 8, no. 2-4 (2014), p. 284-298
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- Description: A financial view is proposed for reliability evaluation of multi-state weighted k-out-of-n:F systems. Failure cost as the cost which is imposed on the components by failures is used to denote the importance weight of each component. The deterioration process of components over time is modelled by Markov chain. System failure behaviour is formulated by Universal Generating Function (UGF). Furthermore, the present value of system failure is calculated by considering time value of money. As a result, the system reliability is demonstrated as cost which is more sensible for managers. A numerical example is presented to illustrate the proposed approach. After that, a way is suggested to transform the system cost present value into system reliability value. MATLAB programming is developed to make a sensitivity analysis on example results. Therefore, the impact of maintenance activities is investigated to show how they can reduce system cost through improving the system reliability. Copyright © 2014 Inderscience Enterprises Ltd.
Data-Driven System Reliability and Failure Behavior Modeling Using FMECA
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2016
- Type: Text , Journal article
- Relation: IEEE Transactions on Industrial Informatics Vol. 12, no. 3 (2016), p. 1253-1260
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- Description: System reliability modeling needs a large amount of data to estimate the parameters. In addition, reliability estimation is associated with uncertainty. This paper aims to propose a new method to evaluate the failure behavior and reliability of a large system using failure modes, effects, and criticality analysis (FMECA). Therefore, qualitative data based on the judgment of experts are used when data are not sufficient. The subjective data of failure modes and causes have been aggregated through the system to develop an overall failure index (OFI). This index not only represents the system reliability behavior, but also prioritizes corrective actions based on improvements in system failure. In addition, two optimization models are presented to select optimal actions subject to budget constraint. The associated costs of each corrective action are considered in risk evaluation. Finally, a case study of a manufacturing line is introduced to verify the applicability of the proposed method in industrial environments. The proposed method is compared with conventional FMECA approach. It is shown that the proposed method has a better performance in risk assessment. A sensitivity analysis is provided on the budget amount and the results are discussed. © 2015 IEEE.
On reliability evaluation of multistate weighted k -out-of- n system using present value
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2015
- Type: Text , Journal article
- Relation: Engineering Economist Vol. 60, no. 1 (2015), p. 22-39
- Full Text: false
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- Description: A new reliability evaluation methodology for multistate weighted k-out-of-n systems is presented in this article. The present value of the cash flow generated by the system components is used as a reliability value. We take a financial view of reliability and consider functioning periods and the time value of money in system reliability analysis. Two approaches, the universal generating function (UGF) and recursive algorithm, are applied to evaluate the reliability of the multistate weighted k-out-of-n system. An illustrative example is calculated based on the proposed system reliability evaluation methodology. It is shown that this evaluation method can also be used to find the value of the maintenance policy. Finally, the UGF and recursive algorithm approaches are compared with each other for large system reliability assessment. [ABSTRACT FROM AUTHOR] Copyright of Engineering Economist is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Reliability centered maintenance using system dynamics approach
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2015
- Type: Text , Conference paper
- Relation: 2015 IEEE International Conference on Industrial Technology (ICIT) p. 1932-1936
- Full Text: false
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- Description: This paper presents a system dynamic modeling technique for reliability centered maintenance (RCM). It provides a simulation model to analyze the impact of maintenance strategies such as preventive and corrective maintenance on system availability. Also, maintenance cost is associated with the model to have an optimization view for a manufacturing system. As a result, the optimal decisions can be made based on the results of the model. In addition, sensitivity analysis has been conducted for various parameters in the simulation model. The results were compared and discussed for various conditions.
Applying UGF Concept to Enhance the Assessment Capability of FMEA
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2016
- Type: Text , Journal article
- Relation: Quality and Reliability Engineering International Vol. 32, no. 3 (Apr 2016), p. 1085-1093
- Full Text: false
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- Description: The purpose of this paper is to propose a modified version of Failure Mode and Effects Analysis (FMEA) to alleviate its drawbacks. FMEA is an important tool in risk evaluation and finding the priority of potential failure modes for corrective actions. In the proposed method, the Universal Generating Function (UGF) approach has been used to improve the assessment capability of the conventional Risk Priority Number (RPN) in ranking. The new method is named as URPN. It generates the most number of unique values in comparison with the previous methods and considers relative importance for the parameters while it is easy to compute. More unique numbers help to avoid from having the same priority level for different failure modes which represent various risk levels. A case study has been employed to demonstrate that the URPN not only can improve the shortcomings but also is able to provide accurate values for risk assessment. Copyright (c) 2015 John Wiley & Sons, Ltd.
A value-driven approach for optimizing reliability-redundancy allocation problem in multi-state weighted k-out-of-n system
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2016
- Type: Text , Journal article
- Relation: Journal of Manufacturing Systems Vol. 40, no. (2016), p. 54-62
- Full Text: false
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- Description: This study concentrates on optimizing a multi-state weighted k-out-of-n system consisting of different types of reparable components. An optimization model is developed to decide upon both optimal redundancy allocation and best maintenance activities for reliability allocation. The optimization model is to maximize system reliability and minimize system cost simultaneously. To reach this goal, a financial view has been employed to estimate the system reliability, and combine it with system cost. The proposed model determines the number of each component type in the system, and the maintenance actions and the time at which they should be applied. Also, the model is programmed by MATLAB, and Genetic Algorithm is used to solve a practical case. (C) 2016 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.