Reliability Methods (reliability + methods)

Distribution by Scientific Domains


Selected Abstracts


Reliability in grid computing systems,

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 8 2009
Christopher Dabrowski
Abstract In recent years, grid technology has emerged as an important tool for solving compute-intensive problems within the scientific community and in industry. To further the development and adoption of this technology, researchers and practitioners from different disciplines have collaborated to produce standard specifications for implementing large-scale, interoperable grid systems. The focus of this activity has been the Open Grid Forum, but other standards development organizations have also produced specifications that are used in grid systems. To date, these specifications have provided the basis for a growing number of operational grid systems used in scientific and industrial applications. However, if the growth of grid technology is to continue, it will be important that grid systems also provide high reliability. In particular, it will be critical to ensure that grid systems are reliable as they continue to grow in scale, exhibit greater dynamism, and become more heterogeneous in composition. Ensuring grid system reliability in turn requires that the specifications used to build these systems fully support reliable grid services. This study surveys work on grid reliability that has been done in recent years and reviews progress made toward achieving these goals. The survey identifies important issues and problems that researchers are working to overcome in order to develop reliability methods for large-scale, heterogeneous, dynamic environments. The survey also illuminates reliability issues relating to standard specifications used in grid systems, identifying existing specifications that may need to be evolved and areas where new specifications are needed to better support the reliability. Published in 2009 by John Wiley & Sons, Ltd. [source]


Cohesive-zone models, higher-order continuum theories and reliability methods for computational failure analysis,

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2004
René de Borst
Abstract A concise overview is given of various numerical methods that can be used to analyse localization and failure in engineering materials. The importance of the cohesive-zone approach is emphasized and various ways to incorporate the cohesive-zone methodology in discretization methods are discussed. Numerical representations of cohesive-zone models suffer from a certain mesh bias. For discrete representations this is caused by the initial mesh design, while for smeared representations it is rooted in the ill-posedness of the rate boundary value problem that arises upon the introduction of decohesion. A proper representation of the discrete character of cohesive-zone formulations which avoids any mesh bias can be obtained elegantly when exploiting the partition-of-unity property of finite element shape functions. The effectiveness of the approach is demonstrated for some examples at different scales. Moreover, examples are shown how this concept can be used to obtain a proper transition from a plastifying or damaging continuum to a shear band with gross sliding or to a fully open crack (true discontinuum). When adhering to a continuum description of failure, higher-order continuum models must be used. Meshless methods are ideally suited to assess the importance of the higher-order gradient terms, as will be shown. Finally, regularized strain-softening models are used in finite element reliability analyses to quantify the probability of the emergence of various possible failure modes. Copyright © 2004 John Wiley & Sons, Ltd. [source]


Quality management and Juran's legacy

QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 6 2007
Soren Bisgaard
Abstract Quality management provides the framework for the industrial application of statistical quality control, design of experiments, quality improvement and reliability methods. It is therefore helpful for quality engineers and statisticians to be familiar with basic quality management principles. In this article we discuss Dr Joseph M. Juran's important contributions to modern quality management concepts, principles and models. Many people have contributed to modern quality management. However, through his extensive writings covering more than six decades, Juran has managed to distill and synthesize the subject. He has provided us with a coherent framework and terminology and anticipated many of the principles that subsequently became incorporated under the Six Sigma umbrella. We briefly outline Juran's framework and discuss a number of key contributions he has made to the subject of managing for quality. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Set theoretic formulation of performance reliability of multiple response time-variant systems due to degradations in system components

QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 2 2007
Young Kap Son
Abstract This paper presents a design stage method for assessing performance reliability of systems with multiple time-variant responses due to component degradation. Herein the system component degradation profiles over time are assumed to be known and the degradation of the system is related to component degradation using mechanistic models. Selected performance measures (e.g. responses) are related to their critical levels by time-dependent limit-state functions. System failure is defined as the non-conformance of any response and unions of the multiple failure regions are required. For discrete time, set theory establishes the minimum union size needed to identify a true incremental failure region. A cumulative failure distribution function is built by summing incremental failure probabilities. A practical implementation of the theory can be manifest by approximating the probability of the unions by second-order bounds. Further, for numerical efficiency probabilities are evaluated by first-order reliability methods (FORM). The presented method is quite different from Monte Carlo sampling methods. The proposed method can be used to assess mean and tolerance design through simultaneous evaluation of quality and performance reliability. The work herein sets the foundation for an optimization method to control both quality and performance reliability and thus, for example, estimate warranty costs and product recall. An example from power engineering shows the details of the proposed method and the potential of the approach. Copyright © 2006 John Wiley & Sons, Ltd. [source]