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Scale-free networks, as one major class of complex networks, are characterized by a specific structural feature of power-law degree distributions. Examples of scale-free real-world networks include World Wide Web (WWW), email networks, citation and co-author scientific networks, social networks (Facebook, Twitter), networks of Internet routers, and protein-protein interaction networks.
A Variable Frequency Drive (VFD) is a system that can control speed, torque and position of AC motors. In process automation and motion control for various industrial and commercial applications such as cooling fans, pumps, belt conveyors, rotary kilns, and elevators, VFDs are used. Reliability of a VFD is application-dependent, as the magnitude and type of failure-governing stresses vary with each...
Engineers often need to estimate component reliabilities from system failure data that are obtained either from in-house tests or field operations. The components that caused the system failures usually can be identified by checking the failed systems; however, in some cases, the exact cause of failure is very difficult or impossible to identify. For the latter case, the information on the system...
In this paper we use a five-state model to describe the progression of invasive breast cancer. The states of the model are: 1. Healthy or non-detectable cancer, 2. Preclinical (screening detectable cancer), 3. Clinical (symptoms are evident), 4. Death due to breast cancer, and 5. Death due to causes other than breast cancer. We model the natural progression of breast cancer from healthy state to clinical...
In order to achieve an optimal design of a complex space system that meets all constraints, the requirements placed upon the performance, mass, cost, and risk of the system must be considered, understood and traded against each other during the conceptual design of the system to avoid costly redesigns or project cancellation later in the development process [1]. A design process that follows this...
Presented are a number of important experiences gained and lessons learned from the collaboration of the National Aeronautics and Space Administration (NASA) and the Japanese Aerospace Exploration Agency (JAXA) on the CoNNeCT (Communications, Navigation, and Networking re-Configurable Testbed) project. Both space agencies worked on the CoNNeCT Project to design, assemble, test, integrate, and launch...
Three-phase inverters are physically large, complex and expensive elements of major solar power generation systems. The inverter converts DC power created by the photovoltaic (PV) panels to AC power suitable for adding to the power grid.
Reliability prediction methodologies, especially those centered on Military Handbook (MIL-HDBK) 217 and its progeny are highly controversial in their application. The use of reliability predictions in the design and operation of military applications have been in existence since the 1950's. Various textbooks, articles, and workshops have provided insight on the pros and cons of these prediction methodologies...
This paper outlines a method that can be used for field reliability prediction using degradation data and environmental data. From different perspectives about the effects of dynamic environment on field reliability, we proposed two methods to relate the environmental variables to degradation process. The modeling technique and estimation method are illustrated by an example to predict the field failure...
The authors of this paper derived solid state drive (SSD) life time distribution from physics-based life model considering the random nature of real world customer data usage and product inherent physical properties. The paper is focused on the following two cases: Case 1: When only field write duty cycle is treated as a random variable while assuming all other physical characteristics are non-random,...
Accelerated life testing (ALT) is widely used to expedite failures of a product in a short time period for predicting the product's reliability under normal operating conditions. The resulting ALT data are often characterized by a probability distribution, such as Weibull, Lognormal, Gamma distribution, along with a life-stress relationship. However, if the selected failure time distribution is not...
Every organization requires a business continuity plan (BCP) or disaster recovery plan (DRP) which falls within cost constraints while achieving the target recovery requirements in terms of recovery time objective (RTO) and recovery point objective (RPO). The organizations must identify the likely events that can cause disasters and evaluate their impact. They need to set the objectives clearly, evaluate...
This paper considers the reliability analysis of phased-mission systems (PMS) subject to competing failure propagation and failure isolation effects. A propagated failure with global effect (PFGE) originating from a system component is a failure that causes damage to all other system components besides the component itself. However, in systems subject to the functional dependence (FDEP) behavior,...
This paper presents a case study depicting the use of a number of Reliability Tools following the: Define, Measure, Analyze, Improve, and Control (DMAIC) process to attain gains. A Failure Reporting Analysis and Corrective Action System (FRACAS) database is used to identify (hardware failure / program money) problems. A well-defined FRACAS database with a solidly defined root cause classification...
Machine fault diagnosis is a field of mechanical engineering concerned with finding faults arising in machines. In this paper, we use the Bayesian network (BN) classifiers and data mining technology to diagnose different kinds of rotor faults in machinery fault simulator (MFS) under varied loads. First of all, three kinds of popular BN classifiers are introduced as the diagnosis model for rotor fault,...
Reliability Engineering is a complex discipline in and of itself. The numeric implications are many times difficult to model in real world terms. The problem is compounded by the combination of internal and external influences such that it sometimes becomes easy to become distanced from the full implications of the analytical activities at hand. Such was the case of what is referred to as EQPT. This...
The ISO 26262 standard is strongly affecting today's development behavior in the Automotive Industry. It defines the new development process requirements for the shift from the quality management system (QMS, ISO/TS 16949) to a safety oriented work culture. There are four key barriers to make this shift; 1) the existing business decision environment based only on cost, 2) the typical project work...
Software reliability prediction models, which receive the most attention in software reliability engineering, use the failure data collected in testing phases to predict the failure occurrence in the operational environment. Currently, as the requirement for reliable software is increasing, ways to predict and estimate the reliability of software systems which require high reliability with small size...
This paper proposes a new approach to study reliability of locomotive wheels with Bayesian framework, utilizing locomotive wheel degradation data sets that can be small or incomplete. In our study, a linear degradation path is assumed and locomotive wheels' installation positions are considered as covariates. A Markov Chain Monte Carlo (MCMC) computational method is also implemented. In the case study,...
Industrial manufacturing systems are becoming more complex; this complexity introduces additional interdependencies between components and systems. To cope with this, new maintenance policies like condition monitoring and prognostics are developed to predict the remaining useful life (RUL) of components. However, decision making based on these predictions is a still underexplored area of maintenance...
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