Maintainability

Power system components are susceptible to failures which causes undesirable interruptions to consumer's power supply thus affecting the overall power system availability. Reliability evaluation is therefore important in power system studies to ensure continuity of power supply in line with the country's increasing population and the need to foster industrialization. This study is centered on reliability assessment of Mofor Injection Substation. This assessment evaluates the performance of the Mofor Injection substation considering various system parameters which contribute to the seamless operation of the station. Historical data obtained from the power substations from January, 2017 to December, 2017 were used to analyze the Injection Substation power reliability. The results obtained revealed a power availability index (ASAI) of 0.7683796 and 0.768968 for Ekete and Orhuwhorun substations respectively. Also, other reliability indices evaluated were SAIDI, CAIDI and SAIFI. The aforementioned reliability results reveals that power distribution at Mofor injection substation can be said to be unreliable, inefficient, undesirable and unstable.

High equipment reliability is a choice and not an accident of fortune. To a great extent you can choose how long you want between equipment failures. You can deliver high equipment reliability by ensuring the chance of incidents that cause failures of equipment parts are low. The secret to remarkably long and trouble-free equipment lives is to keep parts and components at low stress, within good local environmental conditions, so there is little risk they are unable to handle their design duty. If there is nothing to cause a failure, the failure will not happen and your equipment continues in service at full capacity and full availability. For maintenance practitioners, it is the use of precision maintenance backed-up with condition monitoring applied as a tool to prove maintenance work is done precisely, that provides the foundation for exceptional equipment reliability.

The purpose of this work is to present the proposal of a new algorithm to diagnose
domestic washing machines faults using their sound as standalone parameter. To
achieve this and optimize decision making, artificial neural networks are used in line.
A group of actual washing machines noise samples are obtained, with or without
faults, and by comparing and classifying the training samples the failure patterns are
obtained. Finally, a series of tests are performed with another set of samples to
validate the system. The results show a correct detection and classifying of the faults,
and it can be concluded that the proposed algorithm is strong enough to adequately
diagnose incipient faults in the washing machines models tested.
Keywords: neural networks, washing machines, predictive maintenance, incipient
faults

Maintenance based on equipment operability checks is widely used for technical systems of various physical nature. For commercial and military aircraft such checks are carried-out after a certain amount of time according to specific maintenance programs. Therefore, great attention in the research literature is paid to the mathematical modeling of maintenance on the basis of equipment operability checks. In this study, a mathematical model of corrective maintenance with operability checks at discrete times for the safety critical systems is considered. The criterion of the corrective maintenance effectiveness is proposed to provide a given level of operational reliability with minimum maintenance costs. A finite time interval is considered for modeling the moments of the system operability checks. The graph of decision making is analyzed for imperfect operability checks and the probabilities of possible decisions are determined. Analytical equations for the operational reliability and expected maintenance costs are derived for an arbitrary distribution of time to failure. The criteria of determining optimal policies of sequential checks are formulated. Numerical examples illustrate the developed theory. For the first time it has been shown that conditional probabilities of correct and incorrect decisions when checking system operability are dependent on the time of failure and parameters of the degradation model. Numerical calculations have shown that in the case of mixing deteriorating systems with different initial time points of operation, the interval between operability checks converges to a constant periodicity.

Software Maintainability is one of the most important quality attributes. To increase quality of a software, to manage software more efficient and to decrease cost of the software, maintainability, maintainability estimation and maintainability evaluation models have been proposed. However, the practical use of these models in software engineering tools and practice remained little due to their limitations or threats to validity. In this paper, results of our Literature Review about maintainability models, maintainability metrics and maintainability estimation are presented. Aim of this paper is providing a baseline for further searches and serving the needs of developers and customers.

In this article results of researches of strategies of maintenances of fault-tolerant informative systems are described. A design process is carried out on the basis of original approach. This approach is realized on application of structurally - automatics models for construction of Markov models.

Model-based software development, particularly when it utilizes unified modeling language (UML) tools, provides artifacts that make programs more transparent. We use these capabilities to automate major steps in the generation of a software FMEA. Automation not only reduces the labor required but also makes the process repeatable and removes many subjective decisions that can impair the credibility of a software

Heterogeneous systems are becoming increasingly relevant, due to their performance and energy efficiency capabilities, being present in all types of computing platforms, from embedded devices and servers to HPC nodes in large data centers. Their complexity implies that they are usually used under the task paradigm and the host-device programming model. This strongly penalizes accelerator utilization and system energy consumption, as well as making it difficult to adapt applications.

Co-execution allows all devices to simultaneously compute the same problem, cooperating to consume less time and energy. However, programmers must handle all device management, workload distribution and code portability between systems, significantly complicating their programming.

This thesis offers contributions to improve performance and energy efficiency in these massively parallel systems. The proposals address the following generally conflicting objectives: usability and programmability are improved, while ensuring enhanced system abstraction and extensibility, and at the same time performance, scalability and energy efficiency are increased. To achieve this, two runtime systems with completely different approaches are proposed.

EngineCL, focused on OpenCL and with a high-level API, provides an extensible modular system and favors maximum compatibility between all types of devices. Its versatility allows it to be adapted to environments for which it was not originally designed, including applications with time-constrained executions or molecular dynamics HPC simulators, such as the one used in an international research center.

Considering industrial trends and emphasizing professional applicability, CoexecutorRuntime provides a flexible C++/SYCL-based system that provides co-execution support for oneAPI technology. This runtime brings programmers closer to the problem domain, enabling the exploitation of dynamic adaptive strategies that improve efficiency in all types of applications.

Freight bogies are often built using friction element instead of viscous dampers with great advantage regarding cost and manutenibility. On the other hand this technical choice leads to low performance of the vehicle. The aim of this work is to evaluate the behaviour of a Y25 freight bogie that is the most diffuse in Europe where friction dampers are used to reduce vertical and hunting vibrations. The purpose is also to improve a bi-dimensional model of friction damper and to test its numerical efficiency on a whole vehicle model in a multibody code.

Reliability, availability and maintainability (RAM) analysis of a system is helpful in carrying out design modifications, if any, and it is required to achieve minimum failures or to increase mean time between failures (MTBF), and thus it is used to plan maintainability requirements, optimise reliability and maximum equipment availability. To this effect, this paper presents the application of RAM analysis in the process industry. Fuzzy Lambda?Tau methodology is used here to model the system behaviour. Each system components, failure rate and repair time are represented by triangular fuzzy numbers with known spread. The methodology uses Petri nets to model the system instead of fault tree because it allows efficient simultaneous generation of minimal cuts and path sets. Various reliability parameters such as MTBF, expected number of failures (ENOF), reliability, availability, etc. are calculated. The computed results are presented to plant personnel for their performance considerably by adopting and practicing suitable maintenance policies/strategies.

Service dependability has been recognized in the transportation literature as an effective measure of transit systems quality. Dependability models link this measure of service quality with reliability, availability and maintainability characteristics of the subsystems operating in the transport system. The purpose of this paper is to present a dependability model for the analysis of the impact of power electronics reliability on the service dependability in the case of a vehicle for high speed railway applications

School facilities have the important role to ensure the quality of teaching and learning with respect to achieve quality of education. The performance of school facilities significantly affected on student achievement. Therefore, the study on measuring school facility performance is basically important to be taken in order to provide appropriate teaching and learning environment. This paper aims to discuss about framework on measuring the performance of school facilities in public primary school in Batubara district in Indonesia. The concept of facility conditions that identified by Schneider is applied as a basis to measure school facilities performance. The proposed framework is structured through distributed questionnaire spread over Batubara district in order to find the level of school facilities performance from stakeholder perspective, in this case for those who work in school that using facilities. The level of school performance will be ranged from poor to excellent. The results are expected to be used as a guide for school to improve school facilities in public primary school in Indonesia concurrently leading to the improvement of the quality of education in Indonesia in the future.

The ever increasing performance and economy of operation requirements placed on transport aircraft are resulting in very complex, highly integrated digital aircraft control systems. Despite the great increase in complexity mandated by these integrated aircraft control and management systems, substantial improvements in reliability, maintainability, weight savings, manufacturability, and survivability are also required. Fly-By-Light (FBL) and Power-By-Wire (PBW) technologies and their

During the course of the industrial 4.0 era, companies have been exponentially developed and have digitized almost the whole business system to stick to their performance targets and to keep or to even enlarge their market share. Maintenance function has obviously followed the trend as it’s considered one of the most important processes in every enterprise as it impacts a group of the most critical performance indicators such as: cost, reliability, availability, safety and productivity. E-maintenance emerged in early 2000 and now is a common term in maintenance literature representing the digitalized side of maintenance whereby assets are monitored and controlled over the internet. According to literature, e-maintenance has a remarkable impact on maintenance KPIs and aims at ambitious objectives like zero-downtime.

Probability distributions play an important role in the reliability studies and have many applications in engineering. Estimation of the distribution parameters is also significant for making a decision. It is difficult to trap the global solution for the estimation of parameters by the traditional methods such as maximum likelihood estimator (MLE), as these methods trap a local solution. To get the global values of these parameters is complicated. In this paper, we have developed a two-phase approach by taking the advantages of one of the evolutionary algorithms, namely the particle swarm optimization (PSO) for getting the global values of the distribution parameters. PSO exploits the concept of the moment method to estimate the distribution parameters by using mean, standard deviation, coefficient of variation (CV) and Anderson–Darling (AD) statistics for the best fitting of the distribution to failure data. In comparison with the widely used algorithms, a meta-heuristic algorithm (PSO) offers much more choices for system designers.

Abstract : Lessons 21 will present the big picture of systems acquisition as well as the specific contributions made by the Human Factors Engineering (HFE) community to the acquisition process. The human engineer is fundamentally concerned with making sure that the best possible designs are provided within the constraints of time, money, and technical capability. The level of human factors input to systems acquisition is not determined by the cost of the system alone, but by the extent to which the system needs to be human engineered. Lesson 22 will define exactly what systems analysis means and show why knowledge of it is so important to a human factors specialist. It will also introduce some of the more common techniques used when conducting a system analysis. In addition, some of the road blocks that can be expected to be encountered will be presented along with ways to avoid. them. The purposes of systems analysis can be neatly packaged into five general areas: Scheduling, Identifyilng limilting factors, Establishing system performance criteria, Identifying and explaining various design options, Evaluating systems. Lesson 23 will present the history of task analysis, what its aims are, what factors go into a task analysis, and the uses of task analysis. Lessons 24 of the Human Factors Engineering Course will finish the topic of task analysis. One of the purposes of task analysis is to ensure that all the human performance requirements for a new man-machine system have been identified. Lessons 25 will discuss some of the practical issues that arise in cost/benefit trade-offs. This lesson should provide some insights into an important area where system and task analysis skills are typically put to use.

A. Rashid and M. Aksit (Eds.): Transactions on AOSD I, LNCS 3880, pp. 36–74, 2006. © Springer-Verlag Berlin Heidelberg 2006 ... Alessandro Garcia 1 , Cláudio Sant'Anna 2 , Eduardo Figueiredo 2 , Uirá Kulesza 2 , ... Carlos Lucena 2 , and Arndt von Staa 2

This article introduces the problem of collocative integ-rity present in long-lived classification schemes thatundergo several changes. A case study of the subject “eugenics” in the Dewey Decimal Classification is pre-sented to illustrate this phenomenon. Eugenics isstrange because of the kinds of changes it undergoes. The article closes with a discussion of subject ontogenyas the name for this phenomenon and describes impli-cations for information searching and browsing