bluuebunny/crossref_metadata_2025_split huggingface dataset:
The robustness of markov reliability models
Authors: Edgar John F. , Tonybendell  
Published: July 2007

AbstractMarkov models are an established part of current systems reliability and availability analysis. They are extensively used in various applications, including, in particular, electrical power supply systems. One of their advantages is that they considerably simplify availability evaluation so that the availability of very large and complex systems can be computed. It is generally assumed, with some justification, that the results obtained from such Markov reliability models are relatively robust.It has, however, been known for some time, that practical time to failure distributions are frequently non‐exponential, particular attention being given in much reliability work to the Weibull family. Morover, recently additional doubt has been case on the validity of the Markov approach, both because of the work of Professor Kline and others on the non‐exponentiality of practical repair time distribution, and because of the advantages to be obtained in terms of modelling visibility of the alternative simulation approach.In this paper we employ results on the ability of the k‐out‐of‐n systems to span the coherent set to investigate the robustness of Markov reliability models based upon a simulation investigation of coherent systems of up to 10 identical components. We treat the case where adequate repair facilities are available for all components. The effects upon the conventional transient and steady‐state measures of Weibull departures from exponentiality are considered. In general, the Markov models are found to be relatively robust, with alterations to failure distributions being more important than those to repair distributions, and decreasing hazard rates more critical than increasing hazard rates. Of the measures studied, the mean time to failure is most sensitive to variations in distributional shape.
Quality and reliability assurance for electronic systems—actions and results
Authors: Ender Urs 
Published: July 2007

AbstractThe changes in the quality assurance organization introduced in recent years in a Swiss firm have led to a substantial improvement in the production quality of electronic circuit boards and to an increase in the reliability of electronic systems. This article demonstrates that the operational reliability of such systems is determined to a great extent by weak points in the electronic components. It follows that an analysis of the causes and the avoidance of such weak points are paramount in controlling the reliability of electronic systems.
Calculation of optimum proof test intervals for maximum availability
Authors: Duke Geoff R. 
Published: July 2007

AbstractFailure mode and effect analysis (FMEA) is often performed when assessing equipment reliability. Some failure modes can occur that are only revealed when a demand is placed upon the system, thus causing a hazard. Such failures are only detectable by regular proof testing of the system. Availability calculations generally do not take into consideration down‐time caused by the duration of such proof tests. Testing of a large system is both laborious and time consuming, and may cause either partial or total system unavailability. Microprocessor based equipment reduces the duration of this task, but the question arises of how often?' The following method shows how the optimum proof test interval can be determined based on Markovian reliability models. It should be borne in mind that figures used in reliability prediction should not be considered to be precise data. Such figures should be treated as approximations for comparative use only. The purpose of this paper is to provide a guide for use by engineers involved in reliability/availability prediction; it serves to replace intuitive decisions.
Surface mount digital package reliability
Authors: Roesch William J. 
Published: July 2007

AbstractThis paper compares the reliability of four surface mount package styles with the standard through‐hole package. Three test boards were fabricated and subjected to environmental and electrical stresses. The relative package performances of SOICs, butt‐soldered DIPs, surface mounted DIPS, and through‐hole DIPs were found to be equal when subjected to stresses exceeding those expected in normal use. PLCC packages were found to be slightly less reliable in humidity environments than the other packages.
FAILURE ANALYSIS ON BIPOLAR INTEGRATED CIRCUITS ATTRIBUTES DAMAGE TO ELECTROSTATIC DISCHARGE
Authors: Wills G. N. 
Published: July 2007

AbstractInvestigation into the failures of input modules at functional testing after assembly revealed unique damage to the emitters of the bipolar custom integrated circuit used as a receiver. Using a form of reverse engineering revealed that the damage could only be produced by a high energy pulse of short duration. Simulating the input circuit using discrete devices confirmed that similar circuit structures with the same applied stresses gave identical results. It was found that an energy level of 275 μJ gave a similar type of damage to that observed from the assembly failures.The mechanism of failure had to explain why this unique damage was produced at random on any one of four input transistors together with the occasional failure (around one in ten) which did not show this type of damage. This type of failure was traced to short circuits breaking down the insulation oxide to supply lines underlying the input track. Because the damage to the emitters of the input transistors could only be produced by pulsing the discharge from input to input, it was concluded that the damage could be electrostatic in nature. When electrostatic protection precautions were introduced at the delivery of the circuit modules and the earlier assembly stages of the equipment, these failures were totally eliminated.
Monte carlo methods in reliability engineering
Authors: Goldfeld A. , Dubi A. 
Published: July 2007

AbstractThe potential of the Monte Carlo method as a common place tool for a broad range of reliability and logistic problems is discussed. The mathematical features of the method are illustrated and biasing methods aimed at reducing the cost of the calculation are described. These methods combine efficiency with simplicity of implementation in multipurpose computer codes. A multipurpose computer code package developed on the basis of the Monte Carlo method is described.
Parameter estimation for the two‐parameter weibull distribution using sample statistics and the Jack‐Knife
Authors: Bissell A. F. 
Published: July 2007

AbstractApproximations are given relating the shape parameter of the two‐parameter Weibull distribution to the coefficient of variation of a complete (uncensored) data set. The accuracy of the approximations over 0.4 < β < 5 is such as to give adequate estimates in most practical applications. For 0‐25 < β < 0.4 and 5 < β < 10, the estimates from the approximation may provide initial values for iterative procedures using moments, maximum likelihood, minimum x2, etc.The simplicity of the functions means that jack‐knife methods may be used to obtain standard errors of estimates, including the scale parameter (9) where a suitable gamma function approximation is incorporated.
Early life failures
Authors: Unger Burton A. 
Published: July 2007

AbstractDevice failures can be classified as event‐dependent, time‐dependent, and a combination of the two, event/time‐dependent failures. Early life failure are dominated by event‐dependent failures, i.e. Electrostatic Discharge (ESD) failures, and mechanical failures (bonds, cracks, etc.) that result from a stress event. Test and failure analysis results supporting the above are reviewed. This paper was presented at the 1985 Semiconductor Device Reliability NATO Workshop.
Strategies for planning experiments using orthogonal arrays and confounding tables
Authors: Tsui Kwok‐Leung 
Published: July 2007

AbstractGenichi Taguchi has popularized a robust design method which employs experimental design techniques to help identify the levels of design factors to improve the quality of products and manufacturing processes. Experimental design techniques are extremely effective for identifying improved factor levels in problems that involve a large number of factors. Taguchi's success in getting engineers to use experimental design techniques is due, at least in large part, to his use of tools and techniques that simplify the experiment planning process. Recognizing the advantages of this approach, this paper proposes a new set of tools, confounding tables, which offer more guidance to experimenters. Confounding tables provide a clear and systematic representation of confounding relationships. They are simple and useful tools for constructing experiment plans, and they enable users easily to evaluate the confounding patterns of a completed plan. We show how confounding tables provide more information than Taguchi's linear graphs, and are useful for a large class of experiment plans.
Use of 2k‐p designs in parameter design
Authors: Song Jae , Lawson John 
Published: July 2007

AbstractThis article shows that a single 2k‐p fractional factorial design matrix and the traditional data analysis techniques associated with this design can be used effectively to achieve the goal of parameter design while reducing the total number of experiments required. A real example is used to compare Taguchi's two‐part design, and S/N analysis to a 2k‐p design and its associated analysis. Also, a flow diagram is presented to guide a practitioner through the parameter design process using a 2k‐p design. This flow diagram provides an annoted guide to the literature on 2k‐p decision and shows the design processes leading to proper choice of design and appropriate data analysis techniques.
The bathtub does not hold water any more
Authors: Wong Kam L. 
Published: July 2007

AbstractThis is the first part of a three part article under the general heading of ‘Off the bathtub onto the roller‐coaster curve’, a short version1 of which was presented at the 1988 Annual Reliability and Maintainability Symposium in U.S.A. The other two parts, to be published in later issues of this journal, are entitled ‘The roller‐coaster curve is in’ and ‘Physical basis for the roller‐coaster hazard rate curve’. This three‐part article provides detailed discussions of the findings leading to the conclusions on the roller‐coaster characteristics for the hazard rate curve for electronics. Part 1 being presented here covers the discussions on problems with the bathtub curve. The problems include making erroneous decisions resulting in reliability demonstration risks against the manufacturers, windfall profits for satellite manufacturers, false claims in reliability growth and reliability prediction accuracy and stress screening shortfalls. More important than the erroneous short‐term decisions is the long‐term reliability engineering methodology development. It is critical that we must reshape the course of reliability methodology development away from the bathtub misconception.
The application of statistical process control in U.K. automotive manufacture: Some research findings
Authors: Dale B. G. , Shaw P. 
Published: July 2007

AbstractThis paper reports on the findings of a questionnaire survey into the use of statistical process control (SPC) in a sample of United Kingdom automotive suppliers. All the 76 respondents had attended the Ford‐approved three‐day course on SPC held at the University of Manchester Institute of Science and Technology (UMIST). The survey investigated the following broad issues of SPC: motivation, implementation, application, suppliers and customers, and benefits. A number of findings surprised the authors; these included the number of organizations who had not appointed a SPC facilitator, organizations experiencing difficulties in deciding what type of control charts to use, control charts being ‘filled‐in’ by people not directly responsible for control of a process, charts being displayed away from work areas and the frankness of some suppliers in declaring that the vast majority of their manufacturing processes are not in a state of statistical control. If there is an overall message arising from the findings it is that the introduction and application of SPC should not be overcomplicated.
The roller‐coaster curve is in
Authors: Wong Kam L. 
Published: July 2007

AbstractThis is the second part of a three‐part article under the general heading of ‘Off the bathtub onto the roller‐coaster curve’, a short version1 of which was presented at the 1988 Annual Reliability and Maintainability Symposium in the U.S.A. The first part was entitled ‘The bathtub does not hold water any more’,2 and the last part, to be published in a later issue of this journal, is entitled ‘Physical basis for the roller‐coaster hazard rate curve’. This three‐part article provides detailed discussions of the findings leading to the conclusions on the roller‐coaster characteristics for the hazard rate curve for electronics. Part 1 discussed problems with the bathtub curve. This part explores the shape of the failure rate curve in view of some recent observations. For more than twenty years investigators studying semiconducting device burn‐in have subscribed to the concept of freak failures, which manifest themselves as a hump on the hazard rate curve. In addition to semiconducting device data several sets of screening data, as well as operational data dating all the way back to 1961, also showed that indeed one can expect electronic systems to have generally decreasing failure rate curves with failure humps on them. The author of this paper calls these curves the roller‐coaster curves.
Risk assessment and optimization of a safety system using the maros simulation package
Authors: Jardine I. J. A. , Jackson D. 
Published: July 2007

AbstractThe performance of a pressure‐surge relief system which acts as a safety mechanism within the export facility of an oil terminal is analysed in detail. Dynamic simulation methods are integrated with failure mode effects analysis to establish the risk of catastrophic failure of the terminal. An optimization procedure is presented which demonstrates the use of simulation to establish suitable inspection, testing and preventive maintenance schedules which maximize the effectiveness of the surge relief system over its design life. The importance of such activities is evident — left unattended the surge‐relief system will not meet minimum safety standards, whereas planned maintenance and testing is shown to improve safety standards above the minimum required.
Failure estimates with replacement/repair
Authors: Singhal S. C. , Amster S. J. 
Published: July 2007

AbstractThe expected number of circuit pack failures is an important input to the accurate planning of the inventory level of spares. The failure rate of a circuit pack depends on its age and is generally higher during the infant mortality period (frequently one year) as compared to the steady‐state period. In some of the existing models, it is assumed that all of the defective circuit packs are replaced with new circuit packs. On the other extreme, some models assume that each of the defective circuit packs is repaired and shipped back to the field. Depending on the modelling assumption, the estimates of expected number of failures can differ by as much as 15 per cent. The Markov process model described in this paper includes a parameter (fraction of non‐repairable circuit packs) which permits us to investigate cases where only a portion of the circuit packs are non‐repairable (i.e. need to be replaced with new circuit packs). The model estimates the expected number of failures based on the infant mortality rate, the steady‐state failure rate, age distribution of the installed circuit packs, growth potential and fraction of non‐repairable circuit packs.
The failure characteristics of mechanical equipment which receives comprehensive maintenance overhaul
Authors: De La Mare R. F. 
Published: July 2007

AbstractResearch into the failure and repair characteristics of such diverse mechanical equipment as centrifugal pumps and compressors, comminution machinery, electrical generators and offshore pipelines has shown that their repairs and overhauls seldom return their performance to a condition which is ‘as good as new’ in a reliability sense.The research reported here was commissioned to test whether this conclusion applied to mining machinery, which was overhauled to exacting maintenance standards. The results showed that these machines eventually exhibited a similar deterioration, which was statistically, significant. Furthermore, the escalation in their real costs of overhaul was of such a magnitude as to justify their systematic and frequent replacement. The evidence suggested that this deterioration in life performance resulted from the wear out of machine components and the bodies of these machines, which could not be remedied properly by successive overhauls.
Fault detection using parameter estimation
Authors: Pouliezos A. , Stavrakakis G. , Lefas C. 
Published: July 2007

AbstractThis paper presents a brief summary of fault‐detection methods using parameter estimation techniques. An overview of the fault‐detection system design methodology is first presented, followed by the principles of parameter‐estimation fault‐detection techniques. Applications from the field of industrial processes are given and finally a case study is described which applies the general techniques to the fault detection of D.C. motors using multiprocessor systems.
Reliability approach for vehicle safety components
Authors: Brunner Franz J. 
Published: July 2007

AbstractOwing to ‘producer's liability for defective products’ the safety‐related components of vehicles have to be designed, tested and manufactured in an appropriate way. Some considerations are presented about useful procedures in design and testing of safety parts which may help to reach the required high reliability and minimize risks. Problem areas are indicated which need more research. In future the reliability approach in automotive industries will come closer to the standards in aeronautics. This trend is accelerated by the rapid use of electronics in automobiles.
A theoretical approach to a transformer reliability problem
Authors: Pollock J. R. , Hale P. W. 
Published: July 2007

AbstractProduct reliability testing of a video monitor, incorporating rapid thermal cycling, highlighted an interesting problem with failure of a small transformer on the analogue card, causing a severe shimmer of the display. A theoretical model describing this problem is presented, and shows how such an approach can assist in understanding the failure mechanism as well as assisting the resolution of certain dilemmas surrounding it.
DoD microcircuit qualification innovation–QML
Authors: Hakim Edward B. 
Published: July 2007

AbstractThe U.S. Department of Defence (DoD) has undertaken the task of modernizing the procedure for qualification of military high‐quality/high‐reliability microcircuits. This new approach, known as generic qualification, will develop a qualified manufacturers list (QML) which will permit certification of design, fabrication, assembly and packaging using an innovative approach. The objective is to have a single process flow on which both commercial and military product will be indistinguishable and only at qualification testing (which is revolutionary) will the differences be evident. The realization of this change is implementation of statistical process control (SPC) methodologies and total quality management (TQM).
Development and reduction of a fault tree for gearboxes of heavy commercial vehicles based on identification of critical components
Authors: Morello Marcelo Guimarães , Cavalca Katia Lucchesi , Silveira Zilda de Castro 
Published: July 2007

AbstractThis work deals with the development and reduction of a fault tree applied to gearboxes of heavy commercial vehicles. The improvement with respect to the classical failure tree analysis (FTA) is to reduce the number of FTA components based on the sensitivity of the system reliability to the statistical parameters of the components failure models during a certain lifetime. These parameters determine the shape and slope of the decreasing reliability curve. The lifetime plays an important role because it is the base for any decision about guarantee time and periodic inspection in vehicle maintenance. As the components are usually in series configuration in this kind of mechanical system, the proposal is to consider only the components to which the system presents a significant sensitivity. A factorial planning with two replicates is applied to identify the system sensitivity with respect to these parameters taking into account the confidence interval in each case, as the parameters are evaluated from a sample with a specific size, which has a significant influence on the confidence limits. Therefore, the lifetime is defined in terms of kilometers and it must be economically viable for the company with respect to guarantee period, vehicle stops and maintenance costs. Following this objective, it is important to highlight that the reliability function sensitivity of the system changes depending on the lifetime and the behavior of each FTA component's reliability (failure model parameters). Then, the fault tree is assembled and successively reduced considering the sensitivity to scale (α) and shape (β) factors for components with Weibull distribution, as well as mean (µ) and standard deviation (σ) for Gaussian and Lognormal distributions, in specific kilometer intervals. This methodology allows a reliability model conception for management of the actions focused on products' guarantee and provides design descriptions for the development areas and manufacturing. In this model, it is possible to obtain information about lifetime to assist in activities of performance studies and optimization in design engineering as well as the identification of problems related to design and manufacturing for several operation intervals. In the present case study, the methodology led to a 30% reduction on the number of components considered in the complete fault tree, contributing to guide future improvements to gearboxes reliability. Copyright © 2007 John Wiley & Sons, Ltd.
Nonlinear optimization of autonomous undersea vehicle sampling strategies for oceanographic data‐assimilation
Authors: Heaney Kevin D. , Gawarkiewicz Glen , Duda Timothy F. , Lermusiaux Pierre F. J. 
Published: July 2007

AbstractThe problem of how to optimally deploy a suite of sensors to estimate the oceanographic environment is addressed. An optimal way to estimate (nowcast) and predict (forecast) the ocean environment is to assimilate measurements from dynamic and uncertain regions into a dynamical ocean model. In order to determine the sensor deployment strategy that optimally samples the regions of uncertainty, a Genetic Algorithm (GA) approach is presented. The scalar cost function is defined as a weighted combination of a sensor suite's sampling of the ocean variability, ocean dynamics, transmission loss sensitivity, modeled temperature uncertainty (and others). The benefit of the GA approach is that the user can determine “optimal” via a weighting of constituent cost functions, which can include ocean dynamics, acoustics, cost, time, etc. A numerical example with three gliders, two powered AUVs, and three moorings is presented to illustrate the optimization approach in the complex shelfbreak region south of New England. © 2007 Wiley Periodicals, Inc.