International Journal of Reliability, Risk and Safety: Theory and ApplicationInternational Journal of Reliability, Risk and Safety: Theory and Application
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Feed provided by International Journal of Reliability, Risk and Safety: Theory and Application. Click to visit.Probabilistic Physics of Failure (PPOF) Reliability Analysis of RF-MEMS Switches under Uncertainty
http://www.ijrrs.com/article_75171_9133.html
MEMS reliability analysis is a challenging area of research which comprises various physics of failure and diverse failure mechanisms. Reliability issues are critical in both design and fabrication phases of MEMS devices as their commercialization is still delayed by these problems. In this research, a hybrid methodology is developed for the reliability evaluation of MEMS devices. Its first step is the identification of dominant failure modes by FMEA, evaluation of failure mechanisms and an updated lifetime estimation by the Bayesian method. The reliability of MEMS devices is studied using probabilistic physics of failure (PPoF) by determining the dominant failure mechanism. Accordingly, a deterministic model is selected for the analysis of the life and reliability of the dominant failure mechanisms. To convert the deterministic model to a probabilistic model, the uncertainty sources affecting the dielectric lifetime are determined. This model is simulated by the utilization of the Monte Carlo method. In the final stage, the results of life estimation are updated using the Bayesian method. Considering wide application and advantages of RF MEMS capacitive switches, it has been selected as a case study. A framework is developed for reliability evaluation of these switches failures due to stiction mechanism. The results contain FMEA table, lifetime estimation in different voltages, number of duty cycles and at the end, updated results of life estimation using the Bayesian method.Sun, 30 Sep 2018 20:30:00 +0100A Study on the Multi-state (r, s)-out-of- n Systems with Dependent Components
http://www.ijrrs.com/article_73323_9133.html
In the study of technical systems in reliability engineering, multi-state systems play a useful role. A multi-state system is a system consisting n components that system and its components may have several level performance. In the present paper, we introduce the multi-state (r, s)-out-of-n system consisting n elements having the property that each element consists two dependent components and each component of the elements and the system can be in one of m+1 possible states: 0, 1, 2,..., m. We investigate an efficient method to compute the exact reliability by using the distribution of bivariate order statistics. Depending on the number of active components of the multi-state (r, s)-out-of-n systems at time t, the mean residual lifetime function of the system is studied. Also, an example and illustrative graph is provided.Sun, 30 Sep 2018 20:30:00 +0100Triple-Triple Redundant Reliable Onboard Computer Based on Multicore Microcontrollers
http://www.ijrrs.com/article_78197_9133.html
The flight control system must meet extremely high levels of functional integrity and availability. The control algorithm is processed by onboard computer (OBC). To meet the reliability requirements for onboard computers, various type of redundancy must be employed. In this paper, we concerned with the triple modular redundancy (TMR) for an onboard computer with aerospace application. In the proposed architecture, control inputs and system states are measured using designated sensors. According to the acquired data, mission scenario and control algorithm are processed by the processing unit. Thereafter, the results are applied to the system by actuators.TMR technology in component level is used to improve the reliability of OBC according to the system requirements. All of the constituent modules of OBC, comprising processing unit, bus interface, sensor, actuators, and IO devices, benefits from triple redundancy. The case study shows that the similar architecture is used for high reliable flight computer of passenger airplanes except that our architecture is based on the available multicore microcontrollers. The reliability of the designed onboard computer is evaluated analytically, which indicates that the proposed OBC can meet the reliability requirements.Sun, 30 Sep 2018 20:30:00 +0100Improving Reliability and Reducing Power Loss in Power Distribution Network by Determining ...
http://www.ijrrs.com/article_87534_9133.html
The use of capacitor banks in distribution system has many outstanding usages include improving the power factor of a system, voltage profile, and reliability besides the reducing of the power flow losses of the component’s reactive due to the compensation. These benefits depend greatly on how capacitors are placed in the distribution system. Hence, in order to achieve the high reliable construction, switching capacitor has been placed to improve the main challenges of the network designing (reliability and reduce power loss) in the radial distribution system. As regards, the importance of the reliability and power losses are ignored in the distribution networks; the aim of this paper is primarily to establish an objective function for the parallel optimization of these aforementioned parameters. In the simulation process, ten parameters have been compared, which are: System Average Interruption Frequent Index (SAIFI) and its cost, System Average Interruption Duration Index (SAIDI) and its cost, power loss and its cost, the installed capacity and it's cost and values of two objective functions. Honey-bee mating optimization (HBMO) algorithm has been used to solve this problem. Then, the developed technique has been used on the IEEE standard distribution network as a problem-solving system.Sun, 30 Sep 2018 20:30:00 +0100Software Safety Analysis with UML-Based SRBD and Fuzzy VIKOR- Based FMEA
http://www.ijrrs.com/article_70861_9133.html
Software often controls the behavior of mechanical and electrical systems, as well as interactions among their components in cyber-physical systems (CPS). The risks in CPS systems could result in losing tools, features, performance, and even life. Therefore, safety analysis for software in these systems is a highly critical and serious issue. The use of reliability block diagram is a method for checking the safety and reliability of systems. A reliability block diagram is a diagrammatic method for showing how component reliability contributes to the success or failure of a complex system. In this paper, a method for generating RBDs is presented analysis and demonstration of this method capability to evaluation of a software safety by use-case analysis, use-case diagram review, and use-case specification. Then, a Fuzzy VIKOR-based FMEA is used for further evaluation due to the presence of uncertain data. Finally, it is applied to a real CPS.Sun, 30 Sep 2018 20:30:00 +0100Corrosion Reliability Assessment of underground Water Transmission Pipelines by IHS Algorithm
http://www.ijrrs.com/article_80265_9133.html
Lifetime of pipelines is very important for safe and sanitary water transmission pipelines and water distribution networks. For this purpose reliability assessment analysis is a good tool and made it easy or feasible to make more better decision for inspections during maintenance and utilization process. In this study, a non-linear state model of corrosion has been used for the structural analysis of corroded water transmission pipelines, stressed by internal pressure and substance corrosion are considered simultaneous base on a limit state function. In order to take the uncertainty associated with the design and environmental variables into account and obtaining failure probability (reliability index), a improved harmony search meta-heuristic optimization algorithm has been selected. Sensitivity analysis of associated parameters is carried out to measure the effectiveness of each ones on the probability of pipe failure. Results obtained for steel pipeline of Karevandar to Kash water transmission project is discussed as a case study.Sun, 30 Sep 2018 20:30:00 +0100Reliability Model of Fuzzy Consecutive k-out-of-n: F System
http://www.ijrrs.com/article_81435_0.html
Redundancy can be used to increase the reliability of a system. The most popular type of redundancy is k-out-of-n system structure which finds wide applications in both industrial and military systems. A special type of this system is the consecutive k-out-of-n:F system C(k,n:F) which have been proposed for reliability evaluation and design of integrated circuits, microwave relay stations in telecommunication system, oil pipelines systems, vacuum systems in accelerators, computer ring networks, and spacecraft relay stations. In this paper, We discuss a new algorithm for evaluating the fuzzy reliability of any fuzzy linear consecutive k-out-of-n:F system (Lin/C(k,n:F)) with independent, unrepairable, and non-identical components then we take a model for unrepairable system consists of parallel subsystems if each subsystem is Lin/C(k,n:F). due to uncertainty and low sufficient data, the failure time of each component follows fuzzy Rayleigh distribution with one fuzzy parameter. This fuzzy parameter is represented by triangular membership function and estimated from statistical data taken from random samples of each component. Also, a numerical example for a fuzzy unrepairable parallel system with three subsystems is given when each is represented by Lin/C(k,n:F) and the failure time of each component follows fuzzy rayleigh distribution to get analytically and represent graphically the fuzzy reliability function of a this fuzzy system .Sun, 06 Jan 2019 20:30:00 +0100PROBABILISTIC ASSESSMENT OF TWO UNITS PARALLEL SYSTEM WITH CORRELATED LIFETIME UNDER INSPECTION ...
http://www.ijrrs.com/article_88635_0.html
This paper deals with the reliability analysis of a complex system consisting of two dissimilar units’ in a parallel configuration with correlated lifetime distribution. The system stops functioning when both units stop working. Both the units are inspected from time to time and checked before assigning to repair facility. Under consideration of the system have two states: Normal and failed. Regenerative point technique has been used for the mathematical formulation of the model. The system is analyzed using Laplace transforms to solve the mathematical equations. Reliability, Availability, MTSF, Busy Period of repairmen and Cost-effectiveness of the system has been computed. The computed results have been demonstrated by tables and graphs. The repair time of both the units follows the negative exponential distribution with different parameters in a joint probability density function. The inspection times are assumed to follow the general distribution. Some particular cases of the system have also been derived from seeing the practical importance of the model.Mon, 10 Jun 2019 19:30:00 +0100Industry 4.0: Some challenges and opportunities for Reliability Engineering
http://www.ijrrs.com/article_91148_0.html
According to the development of Industry 4.0 and increase the integration of digital, physical and human worlds, reliability engineering must evolve for addressing the existing and future challenges about that. In this paper, the principle of Industry 4.0 is presented and some of these challenges and opportunities for reliability engineering are discussed. New directions for research in system modeling, big data analysis, health management, cyber-physical system, human-machine interaction, uncertainty, jointly optimization, communication, and interfaces are proposed. Each topic can be investigated individually, but this paper summarizes them and prepared a vision about reliability engineering for consideration and discussion by the interested scientific community.Tue, 23 Jul 2019 19:30:00 +0100Moving from One Site to Multi-Site Vulnerability Studies: Decision Analysis for Trade-off ...
http://www.ijrrs.com/article_91332_0.html
This paper provides a vulnerability study for a gas production site. Decision tree analysis is implemented to provide risk-informed decisions on the maintenance strategies to minimize the unavailability and downtime costs. In this context, the decision analysis assesses the impact on the availability of the plant after having decided to buy some spare parts to mitigate criticality of some equipment. This will help the decision makers to make an optimal decision before spending their budget on buying the spare parts while they can reliably forecast a maximized availability. The decision analysis also will move from one site approach to the multi-site vulnerability studies. Results concludes a recommendation for the company on deciding the optimum maintenance strategies and provides a list of required spare parts to be bought in advance to reduce the associated risks and costs.Sun, 28 Jul 2019 19:30:00 +0100Fault-Tolerant Guidance of under-actuated satellite Formation Flying using inter-vehicle ...
http://www.ijrrs.com/article_92136_0.html
In this study, satellite formation flying-guidance is investigated in the presence of under actuation which using inter-vehicle Coulomb force. The Coulomb forces are used to stabilize the formation flying mission. For this purpose, the charge of the satellites to create appropriate attraction and repulsion are determined to maintain distance between the satellites. Equations of the static Coulomb formation of satellites, including three satellites in the triangular form, was developed and the charge value of the Coulomb propulsion system needed for such formation was obtained. By considering Underactuation of one of the formation satellites, the fault-tolerance approach is proposed for achieving mission goals. With this approach, in the first step design of a fault-tolerant guidance law is done and results show stationary formation. In next the step for fulfilling the second goal that is maintaining formation shape and dimension, a fault-tolerant control law is designed.Sun, 18 Aug 2019 19:30:00 +0100