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Reliability growth testing, i.e. the 'growth' of reliability, is a consolidated systematic method used by Fiat Auto to increase and 'demonstrate' reliability while testing vehicles. If a new car model is not very different from th...
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Reliability growth testing, i.e. the 'growth' of reliability, is a consolidated systematic method used by Fiat Auto to increase and 'demonstrate' reliability while testing vehicles. If a new car model is not very different from the previous one (being used as reference), a single 'verification' experimental phase on the vehicles which is consistent with the end product may be sufficient for a reliability statistical demonstration. In this case, the resultant confidence interval may be very large, especially when we want to predict the in field failure frequency after applying corrective actions. Conversely, if the new product shows too many problems, we could obviously define, at any moment, a specific (and more demanding) reliability growth plan and restart the experiments. This paper suggests the cases in which we should choose a reliability growth test or a reliability verification test, whilst considering the total amount of design variations with respect to the reference model: completely new model, resryling, face lifting, etc.
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This study presents a holistic method for constructing a Bayesian network (BN) model for estimating system reliability. BN is a probabilistic approach that is used to model and predict the behavior of a system based on observed st...
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This study presents a holistic method for constructing a Bayesian network (BN) model for estimating system reliability. BN is a probabilistic approach that is used to model and predict the behavior of a system based on observed stochastic events. The BN model is a directed acyclic graph (DAG) where the nodes represent system components and arcs represent relationships among them. Although recent studies on using BN for estimating system reliability have been proposed, they are based on the assumption that a pre-built BN has been designed to represent the system. In these studies, the task of building the BN is typically left to a group of specialists who are BN and domain experts. The BN experts should learn about the domain before building the BN, which is generally very time consuming and may lead to incorrect deductions. As there are no existing studies to eliminate the need for a human expert in the process of system reliability estimation, this paper introduces a method that uses historical data about the system to be modeled as a BN and provides efficient techniques for automated construction of the BN model, and hence estimation of the system reliability. In this respect K2, a data mining algorithm, is used for finding associations between system components, and thus building the BN model. This algorithm uses a heuristic to provide efficient and accurate results while searching for associations. Moreover, no human intervention is necessary during the process of BN construction and reliability estimation. The paper provides a step-by-step illustration of the method and evaluation of the approach with literature case examples.
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Many electronics experts predicted that component failures (in particular, tube failures) in the pioneering ENIAC machine would be so frequent that the machine would never be useful. But the engineers (system architects) and co...
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Many electronics experts predicted that component failures (in particular, tube failures) in the pioneering ENIAC machine would be so frequent that the machine would never be useful. But the engineers (system architects) and component manufacturers improved their art over time to improve the systems availability. Their achievement of remarkably low failure rates should serve as an inspiration to chip- and system-level designers today. Three articles in this general issue of IEEE Micro address the challenge of reliable designs of the future.
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摘要 :
Many electronics experts predicted that component failures (in particular, tube failures) in the pioneering ENIAC machine would be so frequent that the machine would never be useful. But the engineers (system architects) and co...
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Many electronics experts predicted that component failures (in particular, tube failures) in the pioneering ENIAC machine would be so frequent that the machine would never be useful. But the engineers (system architects) and component manufacturers improved their art over time to improve the systems availability. Their achievement of remarkably low failure rates should serve as an inspiration to chip- and system-level designers today. Three articles in this general issue of IEEE Micro address the challenge of reliable designs of the future.
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Network softwarization is a paradigm shift for the next generation of network. Network Function Virtualization (NFV) softwarizes network functions as virtual network function (VNF) instances on top of a network infrastructure. Alo...
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Network softwarization is a paradigm shift for the next generation of network. Network Function Virtualization (NFV) softwarizes network functions as virtual network function (VNF) instances on top of a network infrastructure. Along with the merits of flexibility, programmability and reduced function provisioning cost, softwarization of network functions introduces new challenges of service’s reliability due to possible hardware failures, software bugs and hacker attacks. Currently reliable service provisioning schemes based on first-order statistics fails in accounting for the ultra-reliable needs of mission-critical services. In this paper, we propose a dynamic service chaining (DSC) framework to provision ultra-reliable services where the reliability is characterized by the probability distribution using extreme value theory. Our design objective is to minimize the number of backup VNF modules subject to reliability and resource constraints. Due to the dynamic nature of network, primary and backup VNFs are re-mapped to higher reliable physical machines in order to provide ultra-reliable services. Using Lyapunov stochastic optimization, primary VNF mapping and backup VNF selection are performed in the large and small timescales respectively. Numerical results show that the proposed DSC framework can guarantee ultra-reliable network services efficiently.
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In the reliability assessment of structures, a situation we frequently encounter is that by means of available information some parameters involved can be depicted accurately by their probability distributions and others can only ...
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In the reliability assessment of structures, a situation we frequently encounter is that by means of available information some parameters involved can be depicted accurately by their probability distributions and others can only be described by the bounds or ranges of variations. So, it is meaningful to construct a reliability model by which the probabilistic and nonprobabilistic uncertainties can be treated reasonably in an integrated framework. The main purpose of this paper is to establish a strictly mathematical foundation and a unified framework for reliability assessment and reliability based design optimization (RBDO) of structures in the presence of both probabilistic and nonprobabilistic (bounded) hybrid uncertainties. The input uncertain parameters are divided into two different groups and treated respectively as random variables and interval variables, and the traditional probability and convex set models are adopted to describe the probabilistic and bounded uncertainties, respectively. In the reliability measuring system developed in the paper, dimensionless hybrid reliability indices are defined in different situations by adopting a similar method as for the traditional probabilistic reliability method for structures. A computational procedure for performing the RBDO of structures with hybrid uncertainties is presented. Two numerical examples are investigated to demonstrate the effectiveness and feasibility of the presented method.
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Abstract As the core foundation of reliability engineering and one of the most crucial aspects of general quality, reliability has been attracting increasing attention from industry and academia. Numerous publications on reliabili...
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Abstract As the core foundation of reliability engineering and one of the most crucial aspects of general quality, reliability has been attracting increasing attention from industry and academia. Numerous publications on reliability analysis (RA) have appeared in academic journals, conference proceedings, and technical reports. However, there has not been a systematic summary that covers RA data, models, methods, indicators, and software comprehensively. To fill this gap, this paper analyzed the challenges and the state of the art, as well as determined the future prospects for research on RA. This paper introduces the features of modern complex electromechanical systems (CES), then summarizes the current challenges to the RA of CES. Next, it reviews the latest developments, such as reliability theories, models, methods, and software, then summarizes and compares their advantages and limitations. Finally, it discusses future prospects from the perspectives of reliability data, modeling, decoupling, evaluation indicators, and timely prediction. It is expected that this paper would serve as an introduction to RA for researchers new to this field and as a summary of the current frontiers of RA for experienced researchers.
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In this paper, we demonstrate how we set up and executed an integrated reliability engineering process with the engineering team in the Light Duty (LD) Dodge Ram (DR) Truck chassis program. Organizationally, the LD DR chassis team...
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In this paper, we demonstrate how we set up and executed an integrated reliability engineering process with the engineering team in the Light Duty (LD) Dodge Ram (DR) Truck chassis program. Organizationally, the LD DR chassis team consists of core engineering groups and supporting representatives from other related disciplines. The reliability engineer is a member of the team and he is the reliability advocate and leader. The integrated reliability engineering process was customized and implemented in the LD DR chassis program. Many of the tools developed by the company corporate quality office, such as design failure modes and effect analysis (DFMEA), design verification plan and reporting (DVP&R), and finite element analysis (FEA), were used in supporting the reliability engineering process. An array of technical enablers such as Test Matrix and ReliUp were also developed for supporting the implementation of the reliability engineering process. In the execution, the reliability engineer led the engineering team to set up reliability targets, develop reliability work plans, facilitate up-front design analysis, review and integrate reliability test planning. The reliability engineer also set up the failure reporting, analysis and corrective action system (FRACAS) and managed reliability growth with the team. From the implementation, we have learned several things: (1) an integrated engineering team is crucial in order to develop a product better, quicker and cheaper; (2) a good team leader is the key to product reliability; (3) a capable reliability engineer is the catalyst to a reliability engineering process; (4) the best culture in which to achieve reliability is the delicate balance between 'inside-out' and 'outside-in'; and (5) achieving reliability is far more important than measuring reliability.
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The author reviews developments in mathematical reliability theory, especially those developments which have had or are likely to have impact on engineering reliability problems. The review to 1960 is based on a similar review whi...
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The author reviews developments in mathematical reliability theory, especially those developments which have had or are likely to have impact on engineering reliability problems. The review to 1960 is based on a similar review which appeared in the 1965 book by R.E. Barlow and F. Proschan entitled Mathematical Theory of Reliability. It is pointed out that if the 1970s were the fault tree era, the 1980s may well turn out to be the era of network reliability, principally due to the importance of computer and computer network reliability.
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Mega Railway Projects (MRPs) are expensive and account for an increasing percentage of many a nation’s annual infrastructure expenditure. These MRPs frequently exceed their budget and schedule. The challenge of achieving reliabil...
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Mega Railway Projects (MRPs) are expensive and account for an increasing percentage of many a nation’s annual infrastructure expenditure. These MRPs frequently exceed their budget and schedule. The challenge of achieving reliability or availability targets stands out as a contributing factor to these overruns. A robust and targeted Reliability, Availability, and Maintainability (RAM) process, which covers systems and subsystems that comprise the railway, that is imbedded in the project from the outset and that is managed throughout the life cycle of the project, is crucial for success. However, a RAM process for MRPs is not readily available. While BS EN 50126-1 1 sets out the required RAM related tasks there is no guidance on how these tasks are to be undertaken or managed. This omission is likely to increase the challenge faced by RAM or Systems engineers as they put forth their case for ring-fenced funds and labour at the outset of an MRP. It is therefore important that RAM on an MRP is reviewed so that next steps in developing robust RAM process plan guidelines can be determined. The authors of this paper discuss why RAM is undertaken and the conceptualisation of RAM along with its fundamental features. Its application on railways focusing on RAM techniques and BS EN 50126-1 is outlined. A Systematic Literature Review (SLR) is undertaken to show the state-of-the-art by using a meta and content analysis within the context of railway systems, RAM techniques, RAM standards and Reliability levels. Furthermore, a set of Derived RAM requirements (DRR) based on BS EN 50126-1 are derived to determine the critical areas of RAM and are thus recommended for further development by researchers or RAM practitioners.
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