On Bayesian System Reliability Analysis

Energy Technology Data Exchange (ETDEWEB)

Soerensen Ringi, M

1995-05-01

The view taken in this thesis is that reliability, the probability that a system will perform a required function for a stated period of time, depends on a person`s state of knowledge. Reliability changes as this state of knowledge changes, i.e. when new relevant information becomes available. Most existing models for system reliability prediction are developed in a classical framework of probability theory and they overlook some information that is always present. Probability is just an analytical tool to handle uncertainty, based on judgement and subjective opinions. It is argued that the Bayesian approach gives a much more comprehensive understanding of the foundations of probability than the so called frequentistic school. A new model for system reliability prediction is given in two papers. The model encloses the fact that component failures are dependent because of a shared operational environment. The suggested model also naturally permits learning from failure data of similar components in non identical environments. 85 refs.

On Bayesian System Reliability Analysis

International Nuclear Information System (INIS)

Soerensen Ringi, M.

1995-01-01

The view taken in this thesis is that reliability, the probability that a system will perform a required function for a stated period of time, depends on a person's state of knowledge. Reliability changes as this state of knowledge changes, i.e. when new relevant information becomes available. Most existing models for system reliability prediction are developed in a classical framework of probability theory and they overlook some information that is always present. Probability is just an analytical tool to handle uncertainty, based on judgement and subjective opinions. It is argued that the Bayesian approach gives a much more comprehensive understanding of the foundations of probability than the so called frequentistic school. A new model for system reliability prediction is given in two papers. The model encloses the fact that component failures are dependent because of a shared operational environment. The suggested model also naturally permits learning from failure data of similar components in non identical environments. 85 refs

The Impact of the Reliability of Teleinformation Systems on the Quality of Transmitted Information

Directory of Open Access Journals (Sweden)

Stawowy Marek

2016-10-01

Full Text Available The work describes the impact the reliability of the information quality IQ for information and communication systems. One of the components of IQ is the reliability properties such as relativity, accuracy, timeliness, completeness, consistency, adequacy, accessibility, credibility, congruence. Each of these components of IQ is independent and to properly estimate the value of IQ, use one of the methods of modeling uncertainty. In this article, we used a hybrid method that has been developed jointly by one of the authors. This method is based on the mathematical theory of evidence know as Dempstera-Shafera (DS theory and serial links of dependent hybrid named IQ (hyb.

METHODS OF IMPROVING THE RELIABILITY OF THE CONTROL SYSTEM TRACTION POWER SUPPLY OF ELECTRIC TRANSPORT BASED ON AN EXPERT INFORMATION

Directory of Open Access Journals (Sweden)

O. O. Matusevych

2009-03-01

Full Text Available The author proposed the numerous methods of solving the multi-criterion task – increasing of reliability of control system on the basis of expert information. The information, which allows choosing thoughtfully the method of reliability increasing for a control system of electric transport, is considered.

Reliability of operating WWER monitoring systems

International Nuclear Information System (INIS)

Yastrebenetsky, M.A.; Goldrin, V.M.; Garagulya, A.V.

1996-01-01

The elaboration of WWER monitoring systems reliability measures is described in this paper. The evaluation is based on the statistical data about failures what have collected at the Ukrainian operating nuclear power plants (NPP). The main attention is devoted to radiation safety monitoring system and unit information computer system, what collects information from different sensors and system of the unit. Reliability measures were used for decision the problems, connected with life extension of the instruments, and for other purposes. (author). 6 refs, 6 figs

Reliability of operating WWER monitoring systems

Energy Technology Data Exchange (ETDEWEB)

Yastrebenetsky, M A; Goldrin, V M; Garagulya, A V [Ukrainian State Scientific Technical Center of Nuclear and Radiation Safety, Kharkov (Ukraine). Instrumentation and Control Systems Dept.

1997-12-31

The elaboration of WWER monitoring systems reliability measures is described in this paper. The evaluation is based on the statistical data about failures what have collected at the Ukrainian operating nuclear power plants (NPP). The main attention is devoted to radiation safety monitoring system and unit information computer system, what collects information from different sensors and system of the unit. Reliability measures were used for decision the problems, connected with life extension of the instruments, and for other purposes. (author). 6 refs, 6 figs.

Fog-computing concept usage as means to enhance information and control system reliability

Science.gov (United States)

Melnik, E. V.; Klimenko, A. B.; Ivanov, D. Ya

2018-05-01

This paper focuses on the reliability issue of information and control systems (ICS). The authors propose using the elements of the fog-computing concept to enhance the reliability function. The key idea of fog-computing is to shift computations to the fog-layer of the network, and thus to decrease the workload of the communication environment and data processing components. As for ICS, workload also can be distributed among sensors, actuators and network infrastructure facilities near the sources of data. The authors simulated typical workload distribution situations for the “traditional” ICS architecture and for the one with fogcomputing concept elements usage. The paper contains some models, selected simulation results and conclusion about the prospects of the fog-computing as a means to enhance ICS reliability.

The European reliability data system. An organized information exchange on the operation of European nuclear reactors

International Nuclear Information System (INIS)

Mancini, G.; Amesz, J.; Bastianini, P.; Capobianchi, S.

1983-01-01

The paper revises the aims and objectives of the European Reliability Data System (ERDS), a centralized system collecting and organizing, at European level, information related to the operation of LWRs. The ERDS project was started in 1977 and after a preliminary feasibility study that ended in 1979 is now proceeding towards the final design and implementation stages. ERDS exploits information collected in national data systems and information deriving from single reactor sources. The paper describes first the development of the four data banks constituting the system: Component Event Data Bank, CEDB; Abnormal Occurrences Reporting System, AORS; Operating Unit Status Report, OUSR; and Generic Reliability Parameter Data Bank, GRPDB. Several typical aspects concerning the project are then outlined from the need of homogeneization of data and therefore the need for setting up reference classifications, to the problem of data transcoding and input into the system. Furthermore, the need is stressed of involving much more deeply nuclear power plant operators into the process of data acquisition by providing them with a useful feedback from the data analysis. (author)

Investigation of reliability indicators of information analysis systems based on Markov’s absorbing chain model

Science.gov (United States)

Gilmanshin, I. R.; Kirpichnikov, A. P.

2017-09-01

In the result of study of the algorithm of the functioning of the early detection module of excessive losses, it is proven the ability to model it by using absorbing Markov chains. The particular interest is in the study of probability characteristics of early detection module functioning algorithm of losses in order to identify the relationship of indicators of reliability of individual elements, or the probability of occurrence of certain events and the likelihood of transmission of reliable information. The identified relations during the analysis allow to set thresholds reliability characteristics of the system components.

The dependence of human reliability upon task information content

International Nuclear Information System (INIS)

Hermanson, E.M.; Golay, M.W.

1994-09-01

The role of human error in safety mishaps is an important factor in system design. As systems become increasingly complex the capacity of the human to deal with the added complexity is diminished. It is therefore crucial to understand the relationship between system complexity and human reliability so that systems may be built in such a way as to minimize human error. One way of understanding this relationship is to quantify system complexity and then measure the human reaction in response to situations of varying complexity. The quantification of system complexity may be performed by determining the information content present in the tasks that the human must execute. The purpose of this work is therefore to build and perform a consistent experiment which will determine the extent to which human reliability depends upon task information content. Two main conclusions may be drawn from this work. The first is that human reliability depends upon task information content. Specifically, as the information content contained in a task increases, the capacity of a human to deal successfully with the task decreases monotonically. Here the definition of total success is the ability to complete the task at hand fully and correctly. Furthermore, there exists a value of information content below which a human can deal with the task successfully, but above which the success of an individual decreases monotonically with increasing information. These ideas should be generalizable to any model where system complexity can be clearly and consistently defined

Reliability and optimization of structural systems

International Nuclear Information System (INIS)

Thoft-Christensen, P.

1987-01-01

The proceedings contain 28 papers presented at the 1st working conference. The working conference was organized by the IFIP Working Group 7.5. The proceedings also include 4 papers which were submitted, but for various reasons not presented at the working conference. The working conference was attended by 50 participants from 18 countries. The conference was the first scientific meeting of the new IFIP Working Group 7.5 on 'Reliability and Optimization of Structural Systems'. The purpose of the Working Group 7.5 is to promote modern structural system optimization and reliability theory, to advance international cooperation in the field of structural system optimization and reliability theory, to stimulate research, development and application of structural system optimization and reliability theory, to further the dissemination and exchange of information on reliability and optimization of structural system optimization and reliability theory, and to encourage education in structural system optimization and reliability theory. (orig./HP)

PREP KITT, System Reliability by Fault Tree Analysis. PREP, Min Path Set and Min Cut Set for Fault Tree Analysis, Monte-Carlo Method. KITT, Component and System Reliability Information from Kinetic Fault Tree Theory

International Nuclear Information System (INIS)

Vesely, W.E.; Narum, R.E.

1997-01-01

1 - Description of problem or function: The PREP/KITT computer program package obtains system reliability information from a system fault tree. The PREP program finds the minimal cut sets and/or the minimal path sets of the system fault tree. (A minimal cut set is a smallest set of components such that if all the components are simultaneously failed the system is failed. A minimal path set is a smallest set of components such that if all of the components are simultaneously functioning the system is functioning.) The KITT programs determine reliability information for the components of each minimal cut or path set, for each minimal cut or path set, and for the system. Exact, time-dependent reliability information is determined for each component and for each minimal cut set or path set. For the system, reliability results are obtained by upper bound approximations or by a bracketing procedure in which various upper and lower bounds may be obtained as close to one another as desired. The KITT programs can handle independent components which are non-repairable or which have a constant repair time. Any assortment of non-repairable components and components having constant repair times can be considered. Any inhibit conditions having constant probabilities of occurrence can be handled. The failure intensity of each component is assumed to be constant with respect to time. The KITT2 program can also handle components which during different time intervals, called phases, may have different reliability properties. 2 - Method of solution: The PREP program obtains minimal cut sets by either direct deterministic testing or by an efficient Monte Carlo algorithm. The minimal path sets are obtained using the Monte Carlo algorithm. The reliability information is obtained by the KITT programs from numerical solution of the simple integral balance equations of kinetic tree theory. 3 - Restrictions on the complexity of the problem: The PREP program will obtain the minimal cut and

PV Systems Reliability Final Technical Report.

Energy Technology Data Exchange (ETDEWEB)

Lavrova, Olga [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flicker, Jack David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Johnson, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Armijo, Kenneth Miguel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Sigifredo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schindelholz, Eric John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorensen, Neil R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yang, Benjamin Bing-Yeh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-12-01

The continued exponential growth of photovoltaic technologies paves a path to a solar-powered world, but requires continued progress toward low-cost, high-reliability, high-performance photovoltaic (PV) systems. High reliability is an essential element in achieving low-cost solar electricity by reducing operation and maintenance (O&M) costs and extending system lifetime and availability, but these attributes are difficult to verify at the time of installation. Utilities, financiers, homeowners, and planners are demanding this information in order to evaluate their financial risk as a prerequisite to large investments. Reliability research and development (R&D) is needed to build market confidence by improving product reliability and by improving predictions of system availability, O&M cost, and lifetime. This project is focused on understanding, predicting, and improving the reliability of PV systems. The two areas being pursued include PV arc-fault and ground fault issues, and inverter reliability.

Results of a Demonstration Assessment of Passive System Reliability Utilizing the Reliability Method for Passive Systems (RMPS)

Energy Technology Data Exchange (ETDEWEB)

Bucknor, Matthew; Grabaskas, David; Brunett, Acacia; Grelle, Austin

2015-04-26

Advanced small modular reactor designs include many advantageous design features such as passively driven safety systems that are arguably more reliable and cost effective relative to conventional active systems. Despite their attractiveness, a reliability assessment of passive systems can be difficult using conventional reliability methods due to the nature of passive systems. Simple deviations in boundary conditions can induce functional failures in a passive system, and intermediate or unexpected operating modes can also occur. As part of an ongoing project, Argonne National Laboratory is investigating various methodologies to address passive system reliability. The Reliability Method for Passive Systems (RMPS), a systematic approach for examining reliability, is one technique chosen for this analysis. This methodology is combined with the Risk-Informed Safety Margin Characterization (RISMC) approach to assess the reliability of a passive system and the impact of its associated uncertainties. For this demonstration problem, an integrated plant model of an advanced small modular pool-type sodium fast reactor with a passive reactor cavity cooling system is subjected to a station blackout using RELAP5-3D. This paper discusses important aspects of the reliability assessment, including deployment of the methodology, the uncertainty identification and quantification process, and identification of key risk metrics.

Nuclear plant reliability data system. 1979 annual reports of cumulative system and component reliability

International Nuclear Information System (INIS)

1979-01-01

The primary purposes of the information in these reports are the following: to provide operating statistics of safety-related systems within a unit which may be used to compare and evaluate reliability performance and to provide failure mode and failure rate statistics on components which may be used in failure mode effects analysis, fault hazard analysis, probabilistic reliability analysis, and so forth

Systems reliability/structural reliability

International Nuclear Information System (INIS)

Green, A.E.

1980-01-01

The question of reliability technology using quantified techniques is considered for systems and structures. Systems reliability analysis has progressed to a viable and proven methodology whereas this has yet to be fully achieved for large scale structures. Structural loading variants over the half-time of the plant are considered to be more difficult to analyse than for systems, even though a relatively crude model may be a necessary starting point. Various reliability characteristics and environmental conditions are considered which enter this problem. The rare event situation is briefly mentioned together with aspects of proof testing and normal and upset loading conditions. (orig.)

Reliable computer systems design and evaluatuion

CERN Document Server

Siewiorek, Daniel

2014-01-01

Enhance your hardware/software reliabilityEnhancement of system reliability has been a major concern of computer users and designers ¦ and this major revision of the 1982 classic meets users' continuing need for practical information on this pressing topic. Included are case studies of reliablesystems from manufacturers such as Tandem, Stratus, IBM, and Digital, as well as coverage of special systems such as the Galileo Orbiter fault protection system and AT&T telephone switching processors.

Creation of reliable relevance judgments in information retrieval systems evaluation experimentation through crowdsourcing: a review.

Science.gov (United States)

Samimi, Parnia; Ravana, Sri Devi

2014-01-01

Test collection is used to evaluate the information retrieval systems in laboratory-based evaluation experimentation. In a classic setting, generating relevance judgments involves human assessors and is a costly and time consuming task. Researchers and practitioners are still being challenged in performing reliable and low-cost evaluation of retrieval systems. Crowdsourcing as a novel method of data acquisition is broadly used in many research fields. It has been proven that crowdsourcing is an inexpensive and quick solution as well as a reliable alternative for creating relevance judgments. One of the crowdsourcing applications in IR is to judge relevancy of query document pair. In order to have a successful crowdsourcing experiment, the relevance judgment tasks should be designed precisely to emphasize quality control. This paper is intended to explore different factors that have an influence on the accuracy of relevance judgments accomplished by workers and how to intensify the reliability of judgments in crowdsourcing experiment.

Reliability Modeling of Electromechanical System with Meta-Action Chain Methodology

Directory of Open Access Journals (Sweden)

Genbao Zhang

2018-01-01

Full Text Available To establish a more flexible and accurate reliability model, the reliability modeling and solving algorithm based on the meta-action chain thought are used in this thesis. Instead of estimating the reliability of the whole system only in the standard operating mode, this dissertation adopts the structure chain and the operating action chain for the system reliability modeling. The failure information and structure information for each component are integrated into the model to overcome the given factors applied in the traditional modeling. In the industrial application, there may be different operating modes for a multicomponent system. The meta-action chain methodology can estimate the system reliability under different operating modes by modeling the components with varieties of failure sensitivities. This approach has been identified by computing some electromechanical system cases. The results indicate that the process could improve the system reliability estimation. It is an effective tool to solve the reliability estimation problem in the system under various operating modes.

A computational Bayesian approach to dependency assessment in system reliability

International Nuclear Information System (INIS)

Yontay, Petek; Pan, Rong

2016-01-01

Due to the increasing complexity of engineered products, it is of great importance to develop a tool to assess reliability dependencies among components and systems under the uncertainty of system reliability structure. In this paper, a Bayesian network approach is proposed for evaluating the conditional probability of failure within a complex system, using a multilevel system configuration. Coupling with Bayesian inference, the posterior distributions of these conditional probabilities can be estimated by combining failure information and expert opinions at both system and component levels. Three data scenarios are considered in this study, and they demonstrate that, with the quantification of the stochastic relationship of reliability within a system, the dependency structure in system reliability can be gradually revealed by the data collected at different system levels. - Highlights: • A Bayesian network representation of system reliability is presented. • Bayesian inference methods for assessing dependencies in system reliability are developed. • Complete and incomplete data scenarios are discussed. • The proposed approach is able to integrate reliability information from multiple sources at multiple levels of the system.

ARCHITECTURE AND RELIABILITY OF OPERATING SYSTEMS

Directory of Open Access Journals (Sweden)

Stanislav V. Nazarov

2018-03-01

Full Text Available Progress in the production technology of microprocessors significantly increased reliability and performance of the computer systems hardware. It cannot be told about the corresponding characteristics of the software and its basis – the operating system (OS. Some achievements of program engineering are more modest in this field. Both directions of OS improvement (increasing of productivity and reliability are connected with the development of effective structures of these systems. OS functional complexity leads to the multiplicity of the structure, which is further enhanced by the specialization of the operating system depending on scope of computer system (complex scientific calculations, real time, information retrieval systems, systems of the automated and automatic control, etc. The functional complexity of the OS leads to the complexity of its architecture, which is further enhanced by the specialization of the operating system, depending on the computer system application area (complex scientific calculations, real-time, information retrieval systems, automated and automatic control systems, etc.. That fact led to variety of modern OS. It is possible to estimate reliability of different OS structures only as results of long-term field experiment or simulation modeling. However it is most often unacceptable because of time and funds expenses for carrying out such research. This survey attempts to evaluate the reliability of two main OS architectures: large multi-layered modular core and a multiserver (client-server system. Represented by continuous Markov chains which are explored in the stationary mode on the basis of transition from systems of the differential equations of Kolmogorov to system of the linear algebraic equations, models of these systems are developed.

Reliable computer systems.

Science.gov (United States)

Wear, L L; Pinkert, J R

1993-11-01

In this article, we looked at some decisions that apply to the design of reliable computer systems. We began with a discussion of several terms such as testability, then described some systems that call for highly reliable hardware and software. The article concluded with a discussion of methods that can be used to achieve higher reliability in computer systems. Reliability and fault tolerance in computers probably will continue to grow in importance. As more and more systems are computerized, people will want assurances about the reliability of these systems, and their ability to work properly even when sub-systems fail.

RELIABILITY ASSESSMENT OF ENTROPY METHOD FOR SYSTEM CONSISTED OF IDENTICAL EXPONENTIAL UNITS

Institute of Scientific and Technical Information of China (English)

Sun Youchao; Shi Jun

2004-01-01

The reliability assessment of unit-system near two levels is the most important content in the reliability multi-level synthesis of complex systems. Introducing the information theory into system reliability assessment, using the addible characteristic of information quantity and the principle of equivalence of information quantity, an entropy method of data information conversion is presented for the system consisted of identical exponential units. The basic conversion formulae of entropy method of unit test data are derived based on the principle of information quantity equivalence. The general models of entropy method synthesis assessment for system reliability approximate lower limits are established according to the fundamental principle of the unit reliability assessment. The applications of the entropy method are discussed by way of practical examples. Compared with the traditional methods, the entropy method is found to be valid and practicable and the assessment results are very satisfactory.

A new efficient algorithm for computing the imprecise reliability of monotone systems

International Nuclear Information System (INIS)

Utkin, Lev V.

2004-01-01

Reliability analysis of complex systems by partial information about reliability of components and by different conditions of independence of components may be carried out by means of the imprecise probability theory which provides a unified framework (natural extension, lower and upper previsions) for computing the system reliability. However, the application of imprecise probabilities to reliability analysis meets with a complexity of optimization problems which have to be solved for obtaining the system reliability measures. Therefore, an efficient simplified algorithm to solve and decompose the optimization problems is proposed in the paper. This algorithm allows us to practically implement reliability analysis of monotone systems under partial and heterogeneous information about reliability of components and under conditions of the component independence or the lack of information about independence. A numerical example illustrates the algorithm

Reliability of thermal-hydraulic passive safety systems

International Nuclear Information System (INIS)

D'Auria, F.; Araneo, D.; Pierro, F.; Galassi, G.

2014-01-01

The scholar will be informed of reliability concepts applied to passive system adopted for nuclear reactors. Namely, for classical components and systems the failure concept is associated with malfunction of breaking of hardware. In the case of passive systems the failure is associated with phenomena. A method for studying the reliability of passive systems is discussed and is applied. The paper deals with the description of the REPAS (Reliability Evaluation of Passive Safety System) methodology developed by University of Pisa (UNIPI) and with results from its application. The general objective of the REPAS methodology is to characterize the performance of a passive system in order to increase the confidence toward its operation and to compare the performances of active and passive systems and the performances of different passive systems

Based on Weibull Information Fusion Analysis Semiconductors Quality the Key Technology of Manufacturing Execution Systems Reliability

Science.gov (United States)

Huang, Zhi-Hui; Tang, Ying-Chun; Dai, Kai

2016-05-01

Semiconductor materials and Product qualified rate are directly related to the manufacturing costs and survival of the enterprise. Application a dynamic reliability growth analysis method studies manufacturing execution system reliability growth to improve product quality. Refer to classical Duane model assumptions and tracking growth forecasts the TGP programming model, through the failure data, established the Weibull distribution model. Combining with the median rank of average rank method, through linear regression and least squares estimation method, match respectively weibull information fusion reliability growth curve. This assumption model overcome Duane model a weakness which is MTBF point estimation accuracy is not high, through the analysis of the failure data show that the method is an instance of the test and evaluation modeling process are basically identical. Median rank in the statistics is used to determine the method of random variable distribution function, which is a good way to solve the problem of complex systems such as the limited sample size. Therefore this method has great engineering application value.

Feasibility study for the European Reliability Data System (ERDS)

International Nuclear Information System (INIS)

Mancini, G.

1980-01-01

In the framework of the Reactor Safety Programme of the Commission of the European Communities, the JRC - Ispra Establishment has performed a feasibility study for an integrated European Reliability Data System, the aim of which is the collection and organization of information related to the operation of LWRs with regard to component and systems behaviour, abnormal occurrences, outages, etc. Component Event Data Bank (CEGB), Abnormal Occurrences Reporting System, Generic Reliability Parameter Data Bank, Operating Unit Status Reports and the main activities carried out during the last two years are described. The most important achievements are briefly reported, such as: Reference Classification for Systems, Components and Failure Events, Informatic Structure of the Pilot Experiment of the CEDB, Information Retrieval System for Abnormal Occurrences Reports, Data Bank on Component Reliability Parameters, System on the Exchange of Operation Experience of LWRs, Statistical Data Treatment. Finally, the general conclusions of the feasibility study are summarized: the possibility and the usefulness for the creation of an integrated European Reliability Data System are outlined. (author)

Development of RBDGG Solver and Its Application to System Reliability Analysis

International Nuclear Information System (INIS)

Kim, Man Cheol

2010-01-01

For the purpose of making system reliability analysis easier and more intuitive, RBDGG (Reliability Block diagram with General Gates) methodology was introduced as an extension of the conventional reliability block diagram. The advantage of the RBDGG methodology is that the structure of a RBDGG model is very similar to the actual structure of the analyzed system, and therefore the modeling of a system for system reliability and unavailability analysis becomes very intuitive and easy. The main idea of the development of the RBDGG methodology is similar with that of the development of the RGGG (Reliability Graph with General Gates) methodology, which is an extension of a conventional reliability graph. The newly proposed methodology is now implemented into a software tool, RBDGG Solver. RBDGG Solver was developed as a WIN32 console application. RBDGG Solver receives information on the failure modes and failure probabilities of each component in the system, along with the connection structure and connection logics among the components in the system. Based on the received information, RBDGG Solver automatically generates a system reliability analysis model for the system, and then provides the analysis results. In this paper, application of RBDGG Solver to the reliability analysis of an example system, and verification of the calculation results are provided for the purpose of demonstrating how RBDGG Solver is used for system reliability analysis

An integrated reliability management system for nuclear power plants

International Nuclear Information System (INIS)

Kimura, T.; Shimokawa, H.; Matsushima, H.

1998-01-01

The responsibility in the nuclear field of the Government, utilities and manufactures has increased in the past years due to the need of stable operation and great reliability of nuclear power plants. The need to improve the reliability is not only for the new plants but also for those now running. So, several measures have been taken to improve reliability. In particular, the plant manufactures have developed a reliability management system for each phase (planning, construction, maintenance and operation) and these have been integrated as a unified system. This integrated reliability management system for nuclear power plants contains information about plant performance, failures and incidents which have occurred in the plants. (author)

System Reliability for Offshore Wind Turbines

DEFF Research Database (Denmark)

Marquez-Dominguez, Sergio; Sørensen, John Dalsgaard

2013-01-01

E). In consequence, a rational treatment of uncertainties is done in order to assess the reliability of critical details in OWTs. Limit state equations are formulated for fatigue critical details which are not influenced by wake effects generated in offshore wind farms. Furthermore, typical bi-linear S-N curves...... are considered for reliability verification according to international design standards of OWTs. System effects become important for each substructure with many potential fatigue hot spots. Therefore, in this paper a framework for system effects is presented. This information can be e.g. no detection of cracks...... in inspections or measurements from condition monitoring systems. Finally, an example is established to illustrate the practical application of this framework for jacket type wind turbine substructure considering system effects....

System Reliability Engineering

International Nuclear Information System (INIS)

Lim, Tae Jin

2005-02-01

This book tells of reliability engineering, which includes quality and reliability, reliability data, importance of reliability engineering, reliability and measure, the poisson process like goodness of fit test and the poisson arrival model, reliability estimation like exponential distribution, reliability of systems, availability, preventive maintenance such as replacement policies, minimal repair policy, shock models, spares, group maintenance and periodic inspection, analysis of common cause failure, and analysis model of repair effect.

A reliable information management for real-time systems

International Nuclear Information System (INIS)

Nishihara, Takuo; Tomita, Seiji

1995-01-01

In this paper, we propose a system configuration suitable for the hard realtime systems in which integrity and durability of information are important. On most hard real-time systems, where response time constraints are critical, the data which program access are volatile, and may be lost in case the systems are down. But for some real-time systems, the value-added intelligent network (IN) systems, e.g., integrity and durability of the stored data are very important. We propose a distributed system configuration for such hard real-time systems, comprised of service control modules and data management modules. The service control modules process transactions and responses based on deadline control, and the data management modules deal the stored data based on information recovery schemes well-restablished in fault real-time systems. (author)

Dependent systems reliability estimation by structural reliability approach

DEFF Research Database (Denmark)

Kostandyan, Erik; Sørensen, John Dalsgaard

2014-01-01

Estimation of system reliability by classical system reliability methods generally assumes that the components are statistically independent, thus limiting its applicability in many practical situations. A method is proposed for estimation of the system reliability with dependent components, where...... the leading failure mechanism(s) is described by physics of failure model(s). The proposed method is based on structural reliability techniques and accounts for both statistical and failure effect correlations. It is assumed that failure of any component is due to increasing damage (fatigue phenomena...... identification. Application of the proposed method can be found in many real world systems....

On the safeness of examinees and the reliability of system

International Nuclear Information System (INIS)

Kudo, Kazumi; Kanda, Kosuke; Saito, Kazuhiko; Maesawa, Tsuneharu; Idekami, Tomio

1979-01-01

The control technique of the reliability of examination system was investigated from the viewpoint of patient safety and image information, based on the prevention of microshock owing to circulatory organ checking system. As for the equipments in hospitals, the size of rooms, air conditioning system, power source installation, earth and piping arrangements should be fully discussed at the planning stage. EPR system must be introduced for the prevention for microshock. Intensive education and training are required for operators to secure safeness in operation. Thorough care should be taken to prevent bacilli infection. Further examinations were made on the control technique of the reliability of photographing system from viewpoint of image information, and it is necessary to study the factors for obtaining the reliability of compound machinery components and the devices of generating radiation. (Kobatake, H.)

System ergonomics as an approach to improve human reliability

International Nuclear Information System (INIS)

Bubb, H.

1988-01-01

The application of system technics on ergonomical problems is called system ergonomics. This enables improvements of human reliability by design measures. The precondition for this is the knowledge of how information processing is performed by man and machine. By a separate consideration of sensory processing, cognitive processing, and motory processing it is possible to have a more exact idea of the system element 'man'. The system element 'machine' is well described by differential equations which allow an ergonomical assessment of the manouverability. The knowledge of information processing of man and machine enables a task analysis. This makes appear on one hand the human boundaries depending on the different properties of the task and on the other hand suitable ergonomical solution proposals which improve the reliability of the total system. It is a disadvantage, however, that the change of human reliability by such measures may not be quoted numerically at the moment. (orig.)

European Reliability Data System: main developments and use

International Nuclear Information System (INIS)

Amesz, J.; Capobianchi, S.; Kalfsbeek, H.W.; Mancini, G.

1985-01-01

The paper revises the aims and objectives of the European Reliability Data System (ERDS), a centralized system collecting and organizing information related to the operation of light water reactors. The paper first describes the recent developments of the four data banks constituting the system: Component Event Data Bank, Abnormal Occurrences Reporting System, Operating Unit Status Report and Reliability Parameters Data Bank. Then several issues are discussed referring mostly to the status of classification schemes and their use, to the operation of the banks (data input and transcoding) and to the retrieval and utilization of the information; in this latter case particularly the analysis potential of the data collection scheme of the AORS (Abnormal Occurrences Reporting System) is demonstrated. Finally, emphasis is given to the increasing role which artificial intelligence techniques such as natural language and expert systems and fuzzy logic may play in improving the future capabilities of the system

LED system reliability

NARCIS (Netherlands)

Driel, W.D. van; Yuan, C.A.; Koh, S.; Zhang, G.Q.

2011-01-01

This paper presents our effort to predict the system reliability of Solid State Lighting (SSL) applications. A SSL system is composed of a LED engine with micro-electronic driver(s) that supplies power to the optic design. Knowledge of system level reliability is not only a challenging scientific

Comparing two reliability upper bounds for multistate systems

International Nuclear Information System (INIS)

Meng, Fan C.

2005-01-01

The path-cut reliability bound due to Esary and Proschan [J. Am. Stat. Assoc. 65 (1970) 329] and the minimax reliability bound due to Barlow and Proschan [Statistical Theory of Reliability and Life Testing: Probability Models, 1981] for binary systems have been generalized to multistate systems by Block and Savits [J. Appl. Probab. 19 (1982) 391]. Some comparison results concerning the two multistate lower bounds for various types of multistate systems are given by Meng [Probab. Eng. Inform. Sci. 16 (2002) 485]. In this note we compare the two multistate upper bounds and present results which generalize some previous ones obtained by Maymin [J. Stat. Plan. Inference 16 (1987) 337] for binary systems. Examples are given to illustrate our results

Reliability Approach of a Compressor System using Reliability Block ...

African Journals Online (AJOL)

pc

2018-03-05

Mar 5, 2018 ... This paper presents a reliability analysis of such a system using reliability ... Keywords-compressor system, reliability, reliability block diagram, RBD .... the same structure has been kept with the three subsystems: air flow, oil flow and .... and Safety in Engineering Design", Springer, 2009. [3] P. O'Connor ...

Limits on reliable information flows through stochastic populations.

Science.gov (United States)

Boczkowski, Lucas; Natale, Emanuele; Feinerman, Ofer; Korman, Amos

2018-06-06

Biological systems can share and collectively process information to yield emergent effects, despite inherent noise in communication. While man-made systems often employ intricate structural solutions to overcome noise, the structure of many biological systems is more amorphous. It is not well understood how communication noise may affect the computational repertoire of such groups. To approach this question we consider the basic collective task of rumor spreading, in which information from few knowledgeable sources must reliably flow into the rest of the population. We study the effect of communication noise on the ability of groups that lack stable structures to efficiently solve this task. We present an impossibility result which strongly restricts reliable rumor spreading in such groups. Namely, we prove that, in the presence of even moderate levels of noise that affect all facets of the communication, no scheme can significantly outperform the trivial one in which agents have to wait until directly interacting with the sources-a process which requires linear time in the population size. Our results imply that in order to achieve efficient rumor spread a system must exhibit either some degree of structural stability or, alternatively, some facet of the communication which is immune to noise. We then corroborate this claim by providing new analyses of experimental data regarding recruitment in Cataglyphis niger desert ants. Finally, in light of our theoretical results, we discuss strategies to overcome noise in other biological systems.

Multidisciplinary System Reliability Analysis

Science.gov (United States)

Mahadevan, Sankaran; Han, Song; Chamis, Christos C. (Technical Monitor)

2001-01-01

The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code, developed under the leadership of NASA Glenn Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multidisciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.

Application of fault tree analysis for customer reliability assessment of a distribution power system

International Nuclear Information System (INIS)

Abdul Rahman, Fariz; Varuttamaseni, Athi; Kintner-Meyer, Michael; Lee, John C.

2013-01-01

A new method is developed for predicting customer reliability of a distribution power system using the fault tree approach with customer weighted values of component failure frequencies and downtimes. Conventional customer reliability prediction of the electric grid employs the system average (SA) component failure frequency and downtime that are weighted by only the quantity of the components in the system. These SA parameters are then used to calculate the reliability and availability of components in the system, and eventually to find the effect on customer reliability. Although this approach is intuitive, information is lost regarding customer disturbance experiences when customer information is not utilized in the SA parameter calculations, contributing to inaccuracies when predicting customer reliability indices in our study. Hence our new approach directly incorporates customer disturbance information in component failure frequency and downtime calculations by weighting these parameters with information of customer interruptions. This customer weighted (CW) approach significantly improves the prediction of customer reliability indices when applied to our reliability model with fault tree and two-state Markov chain formulations. Our method has been successfully applied to an actual distribution power system that serves over 2.1 million customers. Our results show an improved benchmarking performance on the system average interruption frequency index (SAIFI) by 26% between the SA-based and CW-based reliability calculations. - Highlights: ► We model the reliability of a power system with fault tree and two-state Markov chain. ► We propose using customer weighted component failure frequencies and downtimes. ► Results show customer weighted values perform superior to component average values. ► This method successfully incorporates customer disturbance information into the model.

Research on reliability management systems for Nuclear Power Plant

International Nuclear Information System (INIS)

Maki, Nobuo

2000-01-01

Investigation on a reliability management system for Nuclear Power Plants (NPPs) has been performed on national and international archived documents as well as on current status of studies at Idaho National Engineering and Environmental Laboratory (INEEL), US NPPs (McGuire, Seabrook), a French NPP (St. Laurent-des-Eaux), Japan Atomic Energy Research Institute (JAERI), Central Research Institute of Electric Power Industries (CRIEPI), and power plant manufacturers in Japan. As a result of the investigation, the following points were identified: (i) A reliability management system is composed of a maintenance management system to inclusively manage maintenance data, and an anomalies information and reliability data management system to extract data from maintenance results stored in the maintenance management system and construct a reliability database. (ii) The maintenance management system, which is widely-used among NPPs in the US and Europe, is an indispensable system for the increase of maintenance reliability. (iii) Maintenance management methods utilizing reliability data like Reliability Centered Maintenance are applied for NPP maintenance in the US and Europe, and contributing to cost saving. Maintenance templates are effective in the application process. In addition, the following points were proposed on the design of the system: (i) A detailed database on specifications of facilities and components is necessary for the effective use of the system. (ii) A demand database is indispensable for the application of the methods. (iii) Full-time database managers are important to maintain the quality of the reliability data. (author)

Hawaii Electric System Reliability

Energy Technology Data Exchange (ETDEWEB)

Loose, Verne William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silva Monroy, Cesar Augusto [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2012-08-01

This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers’ views of reliability “worth” and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers’ views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

Reliability of "Google" for obtaining medical information

Directory of Open Access Journals (Sweden)

Mihir Kothari

2015-01-01

Full Text Available Internet is used by many patients to obtain relevant medical information. We assessed the impact of "Google" search on the knowledge of the parents whose ward suffered from squint. In 21 consecutive patients, the "Google" search improved the mean score of the correct answers from 47% to 62%. We found that "Google" search was useful and reliable source of information for the patients with regards to the disease etiopathogenesis and the problems caused by the disease. The internet-based information, however, was incomplete and not reliable with regards to the disease treatment.

System reliability prediction using data from non-identical environments

International Nuclear Information System (INIS)

Bergman, B.; Ringi, M.

1997-01-01

Since information changes one's mind and probability assessments reflect one's degree of beliefs, a reliability prediction model should enclose all relevant information. Almost always ignored in existing reliability models is the dependence on component life lengths, induced by a common but unknown environment. Furthermore, existing models seldom permit learning from components' performance in similar systems, under the knowledge of non-identical operating environments. In an earlier paper by the present authors the first type of aspects were taken into account and in this paper that model is generalised so that failure data generated from several similar systems in non-identical environments may be used for the prediction of any similar system in its specific environment

Engineering systems reliability, safety, and maintenance an integrated approach

CERN Document Server

Dhillon, B S

2017-01-01

Today, engineering systems are an important element of the world economy and each year billions of dollars are spent to develop, manufacture, operate, and maintain various types of engineering systems around the globe. Many of these systems are highly sophisticated and contain millions of parts. For example, a Boeing jumbo 747 is made up of approximately 4.5 million parts including fasteners. Needless to say, reliability, safety, and maintenance of systems such as this have become more important than ever before.　 Global competition and other factors are forcing manufacturers to produce highly reliable, safe, and maintainable engineering products. Therefore, there is a definite need for the reliability, safety, and maintenance professionals to work closely during design and other phases. Engineering Systems Reliability, Safety, and Maintenance: An Integrated Approach eliminates the need to consult many different and diverse sources in the hunt for the information required to design better engineering syste...

Model of load balancing using reliable algorithm with multi-agent system

Science.gov (United States)

Afriansyah, M. F.; Somantri, M.; Riyadi, M. A.

2017-04-01

Massive technology development is linear with the growth of internet users which increase network traffic activity. It also increases load of the system. The usage of reliable algorithm and mobile agent in distributed load balancing is a viable solution to handle the load issue on a large-scale system. Mobile agent works to collect resource information and can migrate according to given task. We propose reliable load balancing algorithm using least time first byte (LFB) combined with information from the mobile agent. In system overview, the methodology consisted of defining identification system, specification requirements, network topology and design system infrastructure. The simulation method for simulated system was using 1800 request for 10 s from the user to the server and taking the data for analysis. Software simulation was based on Apache Jmeter by observing response time and reliability of each server and then compared it with existing method. Results of performed simulation show that the LFB method with mobile agent can perform load balancing with efficient systems to all backend server without bottleneck, low risk of server overload, and reliable.

Hawaii electric system reliability.

Energy Technology Data Exchange (ETDEWEB)

Silva Monroy, Cesar Augusto; Loose, Verne William

2012-09-01

This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers' views of reliability %E2%80%9Cworth%E2%80%9D and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers' views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

Operator reliability assessment system (OPERAS)

International Nuclear Information System (INIS)

Singh, A.; Spurgin, A.J.; Martin, T.; Welsch, J.; Hallam, J.W.

1991-01-01

OPERAS is a personal-computer (PC) based software to collect and process simulator data on control-room operators responses during requalification training scenarios. The data collection scheme is based upon approach developed earlier during the EPRI Operator Reliability Experiments project. The software allows automated data collection from simulator, thus minimizing simulator staff time and resources to collect, maintain and process data which can be useful in monitoring, assessing and enhancing the progress of crew reliability and effectiveness. The system is designed to provide the data and output information in the form of user-friendly charts, tables and figures for use by plant staff. OPERAS prototype software has been implemented at the Diablo Canyon (PWR) and Millstone (BWR) plants and is currently being used to collect operator response data. Data collected from similator include plant-state variables such as reactor pressure and temperature, malfunction, times at which annunciators are activated, operator actions and observations of crew behavior by training staff. The data and systematic analytical results provided by the OPERAS system can contribute to increase objectivity by the utility probabilistic risk analysis (PRA) and training staff in monitoring and assessing reliability of their crews

Analysis of Parking Reliability Guidance of Urban Parking Variable Message Sign System

OpenAIRE

Zhenyu Mei; Ye Tian; Dongping Li

2012-01-01

Operators of parking guidance and information systems (PGIS) often encounter difficulty in determining when and how to provide reliable car park availability information to drivers. Reliability has become a key factor to ensure the benefits of urban PGIS. The present paper is the first to define the guiding parking reliability of urban parking variable message signs (VMSs). By analyzing the parking choice under guiding and optional parking lots, a guiding parking reliability model was constru...

Reliability analysis of protection system of advanced pressurized water reactor - APR 1400

International Nuclear Information System (INIS)

Varde, P. V.; Choi, J. G.; Lee, D. Y.; Han, J. B.

2003-04-01

Reliability analysis was carried out for the protection system of the Korean Advanced Pressurized Water Reactor - APR 1400. The main focus of this study was the reliability analysis of digital protection system, however, towards giving an integrated statement of complete protection reliability an attempt has been made to include the shutdown devices and other related aspects based on the information available to date. The sensitivity analysis has been carried out for the critical components / functions in the system. Other aspects like importance analysis and human error reliability for the critical human actions form part of this work. The framework provided by this study and the results obtained shows that this analysis has potential to be utilized as part of risk informed approach for future design / regulatory applications

Mass and Reliability System (MaRS)

Science.gov (United States)

Barnes, Sarah

2016-01-01

The Safety and Mission Assurance (S&MA) Directorate is responsible for mitigating risk, providing system safety, and lowering risk for space programs from ground to space. The S&MA is divided into 4 divisions: The Space Exploration Division (NC), the International Space Station Division (NE), the Safety & Test Operations Division (NS), and the Quality and Flight Equipment Division (NT). The interns, myself and Arun Aruljothi, will be working with the Risk & Reliability Analysis Branch under the NC Division's. The mission of this division is to identify, characterize, diminish, and communicate risk by implementing an efficient and effective assurance model. The team utilizes Reliability and Maintainability (R&M) and Probabilistic Risk Assessment (PRA) to ensure decisions concerning risks are informed, vehicles are safe and reliable, and program/project requirements are realistic and realized. This project pertains to the Orion mission, so it is geared toward a long duration Human Space Flight Program(s). For space missions, payload is a critical concept; balancing what hardware can be replaced by components verse by Orbital Replacement Units (ORU) or subassemblies is key. For this effort a database was created that combines mass and reliability data, called Mass and Reliability System or MaRS. The U.S. International Space Station (ISS) components are used as reference parts in the MaRS database. Using ISS components as a platform is beneficial because of the historical context and the environment similarities to a space flight mission. MaRS uses a combination of systems: International Space Station PART for failure data, Vehicle Master Database (VMDB) for ORU & components, Maintenance & Analysis Data Set (MADS) for operation hours and other pertinent data, & Hardware History Retrieval System (HHRS) for unit weights. MaRS is populated using a Visual Basic Application. Once populated, the excel spreadsheet is comprised of information on ISS components including

A New Method of Reliability Evaluation Based on Wavelet Information Entropy for Equipment Condition Identification

International Nuclear Information System (INIS)

He, Z J; Zhang, X L; Chen, X F

2012-01-01

Aiming at reliability evaluation of condition identification of mechanical equipment, it is necessary to analyze condition monitoring information. A new method of reliability evaluation based on wavelet information entropy extracted from vibration signals of mechanical equipment is proposed. The method is quite different from traditional reliability evaluation models that are dependent on probability statistics analysis of large number sample data. The vibration signals of mechanical equipment were analyzed by means of second generation wavelet package (SGWP). We take relative energy in each frequency band of decomposed signal that equals a percentage of the whole signal energy as probability. Normalized information entropy (IE) is obtained based on the relative energy to describe uncertainty of a system instead of probability. The reliability degree is transformed by the normalized wavelet information entropy. A successful application has been achieved to evaluate the assembled quality reliability for a kind of dismountable disk-drum aero-engine. The reliability degree indicates the assembled quality satisfactorily.

The Data Reliability of Volunteered Geographic Information with Using Traffic Accident Data

Science.gov (United States)

Sevinç, H. K.; Karaş, I. R.

2017-11-01

The development of mobile technologies is important in the lives of humans. Mobile devices constitute a great part of the daily lives of people. It has come to such a point that when people first wake up, they check their smart phones for the first thing. Users may share their positions with the GNSS sensors in mobile devices or they can add information about their positions in mobile applications. Users contribute to Geographical Information System with this sharing. These users consist of native (citizens) living in that geographical position not of the CBS specialists. Creating, collecting, sharing and disseminating the geographical data provided by voluntary individuals constitute the Volunteered Geographic Information System. The data in the Volunteered Geographic Information System are received from amateur users. "How reliable will the data received from amateur users instead of specialists of the field be in scientific terms?" In this study, the reliability between the data received from the voluntary users through Volunteered Geographic Information System and real data is investigated. The real data consist of the traffic accident coordinates. The data that will be received from users will be received through the speed values in the relevant coordinates and the marking of the users for possible accident points on the map.

HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 1: HARP introduction and user's guide

Science.gov (United States)

Bavuso, Salvatore J.; Rothmann, Elizabeth; Dugan, Joanne Bechta; Trivedi, Kishor S.; Mittal, Nitin; Boyd, Mark A.; Geist, Robert M.; Smotherman, Mark D.

1994-01-01

The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. HiRel consists of interactive graphical input/output programs and four reliability/availability modeling engines that provide analytical and simulative solutions to a wide host of reliable fault-tolerant system architectures and is also applicable to electronic systems in general. The tool system was designed to be compatible with most computing platforms and operating systems, and some programs have been beta tested, within the aerospace community for over 8 years. Volume 1 provides an introduction to the HARP program. Comprehensive information on HARP mathematical models can be found in the references.

Systems reliability analysis: applications of the SPARCS System-Reliability Assessment Computer Program

International Nuclear Information System (INIS)

Locks, M.O.

1978-01-01

SPARCS-2 (Simulation Program for Assessing the Reliabilities of Complex Systems, Version 2) is a PL/1 computer program for assessing (establishing interval estimates for) the reliability and the MTBF of a large and complex s-coherent system of any modular configuration. The system can consist of a complex logical assembly of independently failing attribute (binomial-Bernoulli) and time-to-failure (Poisson-exponential) components, without regard to their placement. Alternatively, it can be a configuration of independently failing modules, where each module has either or both attribute and time-to-failure components. SPARCS-2 also has an improved super modularity feature. Modules with minimal-cut unreliabiliy calculations can be mixed with those having minimal-path reliability calculations. All output has been standardized to system reliability or probability of success, regardless of the form in which the input data is presented, and whatever the configuration of modules or elements within modules

Criteriom of efficiency of thermometric systems with increased reliability

International Nuclear Information System (INIS)

Sal'nikov, N.L.; Filimonov, E.V.

1995-01-01

Problems on metrological reliability of thermometric systems, intended for temperature regime control at nuclear power facilities are discussed. Thermoelectrical converters and resistance thermoconverters are the most utilized sources of thermometric information at nuclear power plants. Two or more transducers are proposed to be unified in one measurement system in order to increase the accuracy of temperature measurements through obtaining surplus values. Two versions of thermometric systems organization are considered. The first system combined various-type temperature transducers whereas the second system consists of two similar-type transducers. It is established that thermometric systems with various-type transducers are characterized by higher metrological reliability. 3 refs.; 2 figs

Improving Reliability of Information Leakage Detection and Prevention Systems

Directory of Open Access Journals (Sweden)

A. V. Mamaev

2011-03-01

Full Text Available The problem of protection from deliberate leaks of information is one of the most difficult. Integrated systems of information protection against insider have a serious drawback. Using this disadvantage the offender receives the possibility of unauthorized theft of information from working machine.

A novel reliability evaluation method for large engineering systems

Directory of Open Access Journals (Sweden)

Reda Farag

2016-06-01

Full Text Available A novel reliability evaluation method for large nonlinear engineering systems excited by dynamic loading applied in time domain is presented. For this class of problems, the performance functions are expected to be function of time and implicit in nature. Available first- or second-order reliability method (FORM/SORM will be challenging to estimate reliability of such systems. Because of its inefficiency, the classical Monte Carlo simulation (MCS method also cannot be used for large nonlinear dynamic systems. In the proposed approach, only tens instead of hundreds or thousands of deterministic evaluations at intelligently selected points are used to extract the reliability information. A hybrid approach, consisting of the stochastic finite element method (SFEM developed by the author and his research team using FORM, response surface method (RSM, an interpolation scheme, and advanced factorial schemes, is proposed. The method is clarified with the help of several numerical examples.

A Data-Driven Reliability Estimation Approach for Phased-Mission Systems

Directory of Open Access Journals (Sweden)

Hua-Feng He

2014-01-01

Full Text Available We attempt to address the issues associated with reliability estimation for phased-mission systems (PMS and present a novel data-driven approach to achieve reliability estimation for PMS using the condition monitoring information and degradation data of such system under dynamic operating scenario. In this sense, this paper differs from the existing methods only considering the static scenario without using the real-time information, which aims to estimate the reliability for a population but not for an individual. In the presented approach, to establish a linkage between the historical data and real-time information of the individual PMS, we adopt a stochastic filtering model to model the phase duration and obtain the updated estimation of the mission time by Bayesian law at each phase. At the meanwhile, the lifetime of PMS is estimated from degradation data, which are modeled by an adaptive Brownian motion. As such, the mission reliability can be real time obtained through the estimated distribution of the mission time in conjunction with the estimated lifetime distribution. We demonstrate the usefulness of the developed approach via a numerical example.

An approach for assessing ALWR passive safety system reliability

International Nuclear Information System (INIS)

Hake, T.M.

1991-01-01

Many of the advanced light water reactor (ALWR) concepts proposed for the next generation of nuclear power plants rely on passive rather than active systems to perform safety functions. Despite the reduced redundancy of the passive systems as compared to active systems in current plants, the assertion is that the overall safety of the plant is enhanced due to the much higher expected reliability of the passive systems. In order to investigate this assertion, a study is being conducted at Sandia National Laboratories to evaluate the reliability of ALWR passive safety features in the context of probabilistic risk assessment (PRA). The purpose of this paper is to provide a brief overview of the approach to this study. The quantification of passive system reliability is not as straightforward as for active systems, due to the lack of operating experience, and to the greater uncertainty in the governing physical phenomena. Thus, the adequacy of current methods for evaluating system reliability must be assessed, and alternatives proposed if necessary. For this study, the Westinghouse Advanced Passive 600 MWe reactor (AP600) was chosen as the advanced reactor for analysis, because of the availability of AP600 design information. This study compares the reliability of AP600 emergency cooling system with that of corresponding systems in a current generation reactor

Reliability of Power Electronic Converter Systems

DEFF Research Database (Denmark)

-link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...... for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...... electronic converter systems; anomaly detection and remaining-life prediction for power electronics; reliability of DC-link capacitors in power electronic converters; reliability of power electronics packaging; modeling for life-time prediction of power semiconductor modules; minimization of DC...

Reliability analysis and updating of deteriorating systems with subset simulation

DEFF Research Database (Denmark)

Schneider, Ronald; Thöns, Sebastian; Straub, Daniel

2017-01-01

An efficient approach to reliability analysis of deteriorating structural systems is presented, which considers stochastic dependence among element deterioration. Information on a deteriorating structure obtained through inspection or monitoring is included in the reliability assessment through B...... is an efficient and robust sampling-based algorithm suitable for such analyses. The approach is demonstrated in two case studies considering a steel frame structure and a Daniels system subjected to high-cycle fatigue....

Social Information Is Integrated into Value and Confidence Judgments According to Its Reliability.

Science.gov (United States)

De Martino, Benedetto; Bobadilla-Suarez, Sebastian; Nouguchi, Takao; Sharot, Tali; Love, Bradley C

2017-06-21

How much we like something, whether it be a bottle of wine or a new film, is affected by the opinions of others. However, the social information that we receive can be contradictory and vary in its reliability. Here, we tested whether the brain incorporates these statistics when judging value and confidence. Participants provided value judgments about consumer goods in the presence of online reviews. We found that participants updated their initial value and confidence judgments in a Bayesian fashion, taking into account both the uncertainty of their initial beliefs and the reliability of the social information. Activity in dorsomedial prefrontal cortex tracked the degree of belief update. Analogous to how lower-level perceptual information is integrated, we found that the human brain integrates social information according to its reliability when judging value and confidence. SIGNIFICANCE STATEMENT The field of perceptual decision making has shown that the sensory system integrates different sources of information according to their respective reliability, as predicted by a Bayesian inference scheme. In this work, we hypothesized that a similar coding scheme is implemented by the human brain to process social signals and guide complex, value-based decisions. We provide experimental evidence that the human prefrontal cortex's activity is consistent with a Bayesian computation that integrates social information that differs in reliability and that this integration affects the neural representation of value and confidence. Copyright © 2017 De Martino et al.

Multi-Disciplinary System Reliability Analysis

Science.gov (United States)

Mahadevan, Sankaran; Han, Song

1997-01-01

The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code developed under the leadership of NASA Lewis Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multi-disciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.

Pre-Proposal Assessment of Reliability for Spacecraft Docking with Limited Information

Science.gov (United States)

Brall, Aron

2013-01-01

This paper addresses the problem of estimating the reliability of a critical system function as well as its impact on the system reliability when limited information is available. The approach addresses the basic function reliability, and then the impact of multiple attempts to accomplish the function. The dependence of subsequent attempts on prior failure to accomplish the function is also addressed. The autonomous docking of two spacecraft was the specific example that generated the inquiry, and the resultant impact on total reliability generated substantial interest in presenting the results due to the relative insensitivity of overall performance to basic function reliability and moderate degradation given sufficient attempts to try and accomplish the required goal. The application of the methodology allows proper emphasis on the characteristics that can be estimated with some knowledge, and to insulate the integrity of the design from those characteristics that can't be properly estimated with any rational value of uncertainty. The nature of NASA's missions contains a great deal of uncertainty due to the pursuit of new science or operations. This approach can be applied to any function where multiple attempts at success, with or without degradation, are allowed.

76 FR 23171 - Electric Reliability Organization Interpretations of Interconnection Reliability Operations and...

Science.gov (United States)

2011-04-26

... Reliability Standards for the Bulk-Power System, Order No. 693, FERC Stats. & Regs. ] 31,242, order on reh'g...-Power System reliability may request an interpretation of a Reliability Standard.\\7\\ The ERO's standards... information in its reliability assessments. The Reliability Coordinator must monitor Bulk Electric System...

Reliability assessment of complex electromechanical systems under epistemic uncertainty

International Nuclear Information System (INIS)

Mi, Jinhua; Li, Yan-Feng; Yang, Yuan-Jian; Peng, Weiwen; Huang, Hong-Zhong

2016-01-01

The appearance of macro-engineering and mega-project have led to the increasing complexity of modern electromechanical systems (EMSs). The complexity of the system structure and failure mechanism makes it more difficult for reliability assessment of these systems. Uncertainty, dynamic and nonlinearity characteristics always exist in engineering systems due to the complexity introduced by the changing environments, lack of data and random interference. This paper presents a comprehensive study on the reliability assessment of complex systems. In view of the dynamic characteristics within the system, it makes use of the advantages of the dynamic fault tree (DFT) for characterizing system behaviors. The lifetime of system units can be expressed as bounded closed intervals by incorporating field failures, test data and design expertize. Then the coefficient of variation (COV) method is employed to estimate the parameters of life distributions. An extended probability-box (P-Box) is proposed to convey the present of epistemic uncertainty induced by the incomplete information about the data. By mapping the DFT into an equivalent Bayesian network (BN), relevant reliability parameters and indexes have been calculated. Furthermore, the Monte Carlo (MC) simulation method is utilized to compute the DFT model with consideration of system replacement policy. The results show that this integrated approach is more flexible and effective for assessing the reliability of complex dynamic systems. - Highlights: • A comprehensive study on the reliability assessment of complex system is presented. • An extended probability-box is proposed to convey the present of epistemic uncertainty. • The dynamic fault tree model is built. • Bayesian network and Monte Carlo simulation methods are used. • The reliability assessment of a complex electromechanical system is performed.

Reliability analysis of containment isolation systems

International Nuclear Information System (INIS)

Pelto, P.J.; Counts, C.A.

1984-06-01

The Pacific Northwest Laboratory (PNL) is reviewing available information on containment systems design, operating experience, and related research as part of a project being conducted by the Division of Systems Integration, US Nuclear Regulatory Commission. The basic objective of this work is to collect and consolidate data relevant to assessing the functional performance of containment isolation systems and to use this data to the extent possible to characterize containment isolation system reliability for selected reference designs. This paper summarizes the results from initial efforts which focused on collection of data from available documents and briefly describes detailed review and analysis efforts which commenced recently. 5 references

The European reliability data system - ERDS: a state of the art and future developments

International Nuclear Information System (INIS)

Mancini, G.; Amesz, J.; Bastianini, P.; Capobianchi, S.

1982-01-01

In the frame of the Multiannual Nuclear Safety Programme of the Joint Research Centre of the Commisson of the European Communities, a project is being carried out aiming at the creation of a centralized data system collecting and organizing, at European level, information related to the operation of LWRs. The European Reliability Data System ERDS will exploit information already collected in national data systems and information deriving from single reactor sources. The paper describes the development of the four data systems constituting the ERDS: Component Event Data Bank; Abnormal Occurrences Reporting System; Operating Unit Status Report; Generic Reliability Parameter Data Bank

FFTF [Fast Flux Test Facility] reactor shutdown system reliability reevaluation

International Nuclear Information System (INIS)

Pierce, B.F.

1986-07-01

The reliability analysis of the Fast Flux Test Facility reactor shutdown system was reevaluated. Failure information based on five years of plant operating experience was used to verify original reliability numbers or to establish new ones. Also, system modifications made subsequent to performance of the original analysis were incorporated into the reevaluation. Reliability calculations and sensitivity analyses were performed using a commercially available spreadsheet on a personal computer. The spreadsheet was configured so that future failures could be tracked and compared with expected failures. A number of recommendations resulted from the reevaluation including both increased and decreased surveillance intervals. All recommendations were based on meeting or exceeding existing reliability goals. Considerable cost savings will be incurred upon implementation of the recommendations

Reliability of the emergency AC power system at nuclear power plants

International Nuclear Information System (INIS)

Battle, R.E.; Campbell, D.J.; Baranowsky, P.W.

1983-01-01

The reliability of the emergency ac power systems typical of most nuclear power plants was estimated, and the cost and increase in reliability for several improvements were estimated. Fault trees were constructed based on a detailed design review of the emergency ac power systems of 18 nuclear plants. The failure probabilities used in the fault trees were calculated from extensive historical data collected from Licensee Event Reports (LERs) and from operating experience information obtained from nuclear plant licensees. No one or two improvements can be made at all plants to significantly increase the industry-average emergency ac power system reliability; rather the most beneficial improvements are varied and plant specific. Improvements in reliability and the associated costs are estimated using plant specific designs and failure probabilities

Reliability-Based Optimization of Series Systems of Parallel Systems

DEFF Research Database (Denmark)

Enevoldsen, I.; Sørensen, John Dalsgaard

1993-01-01

Reliability-based design of structural systems is considered. In particular, systems where the reliability model is a series system of parallel systems are treated. A sensitivity analysis for this class of problems is presented. Optimization problems with series systems of parallel systems...... optimization of series systems of parallel systems, but it is also efficient in reliability-based optimization of series systems in general....

French power system reliability report 2008

International Nuclear Information System (INIS)

Tesseron, J.M.

2009-06-01

The reliability of the French power system was fully under control in 2008, despite the power outage in the eastern part of the Provence-Alpes-Cote d'Azur region on November 3, which had been dreaded for several years, since it had not been possible to set up a structurally adequate network. Pursuant to a consultation meeting, the reinforcement solution proposed by RTE was approved by the Minister of Energy, boding well for greater reliability in future. Based on the observations presented in this 2008 Report, RTE's Power System Reliability Audit Mission considers that no new recommendations are needed beyond those expressed in previous reliability reports and during reliability audits. The publication of this yearly report is in keeping with RTE's goal to promote the follow-up over time of the evolution of reliability in its various aspects. RTE thus aims to contribute to the development of reliability culture, by encouraging an improved assessment by the different players (both RTE and network users) of the role they play in building reliability, and by advocating the taking into account of reliability and benchmarking in the European organisations of Transmission System Operators. Contents: 1 - Brief overview of the evolution of the internal and external environment; 2 - Operating situations encountered: climatic conditions, supply / demand balance management, operation of interconnections, management of internal congestion, contingencies affecting the transmission facilities; 3 - Evolution of the reliability reference guide: external reference guide: directives, laws, decrees, etc, ETSO, UCTE, ENTSO-E, contracting contributing to reliability, RTE internal reference guide; 4 - Evolution of measures contributing to reliability in the equipment field: intrinsic performances of components (generating sets, protection systems, operation PLC's, instrumentation and control, automatic frequency and voltage controls, transmission facilities, control systems, load

Development of the software for the component reliability database system of Korean nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Han, Sang Hoon; Kim, Seung Hwan; Choi, Sun Young [Korea Atomic Energy Research Institute, Taejeon (Korea)

2002-03-01

A study was performed to develop the system for the component reliability database which consists of database system to store the reliability data and softwares to analyze the reliability data.This system is a part of KIND (Korea Information System for Nuclear Reliability Database).The MS-SQL database is used to stores the component population data, component maintenance history, and the results of reliability analysis. Two softwares were developed for the component reliability system. One is the KIND-InfoView for the data storing, retrieving and searching. The other is the KIND-CompRel for the statistical analysis of component reliability. 4 refs., 13 figs., 7 tabs. (Author)

Reliability and maintainability assessment factors for reliable fault-tolerant systems

Science.gov (United States)

Bavuso, S. J.

1984-01-01

A long term goal of the NASA Langley Research Center is the development of a reliability assessment methodology of sufficient power to enable the credible comparison of the stochastic attributes of one ultrareliable system design against others. This methodology, developed over a 10 year period, is a combined analytic and simulative technique. An analytic component is the Computer Aided Reliability Estimation capability, third generation, or simply CARE III. A simulative component is the Gate Logic Software Simulator capability, or GLOSS. The numerous factors that potentially have a degrading effect on system reliability and the ways in which these factors that are peculiar to highly reliable fault tolerant systems are accounted for in credible reliability assessments. Also presented are the modeling difficulties that result from their inclusion and the ways in which CARE III and GLOSS mitigate the intractability of the heretofore unworkable mathematics.

DESIGN OF WATER-COOLED PACKAGED AIR-CONDITIONING SYSTEMS BASED ON RELIABILITY ASSESSMENT

OpenAIRE

関口, 圭輔; 中尾, 正喜; 藁谷, 至誠; 植草, 常雄; 羽山, 広文

2007-01-01

Water-cooled packaged air-conditioning systems are reevaluated in terms of alleviating the heat island phenomenon in cities and effectively utilizing building rooftops. Up to now, such reliability assessment has been insufficient, and this has limited the use of this kind of air-conditioning system in the information and communications sectors that demand a high reliability. This work has led to the development of a model for evaluating the reliability of water-cooled package air-conditioning...

ON THE EFFECT OF ADAPTIVE USER INTERFACES ON RELIABILITY AND EFFICIENCY OF THE AUTOMATED SYSTEMS

Directory of Open Access Journals (Sweden)

Yu. O. Furtat

2014-01-01

Full Text Available In modern automated systems users often have to face the information overload problem because of ever increasing volumes of information with short time processing requirements. Working in such conditions affects the system operator’s work quality and the systems reliability. One possible approach to solving the information overload problem is to create personalized interfaces that take into account the user’s information management particularities. System operator’s features, which determine the shape and pace of information representation preferred by him, form the user’s cognitive portrait. To determine the values of portrait characteristics professional testing with the assistance of psychologists or operational testing at the user’s workplace is performed. The second option is more preferable for use in automated systems, since it has no issue with lack of psychologists. Cognitive portrait is then built as a result of user interaction with the software diagnostic tools that are based on the cognitive psychology methods. The effect of personalized user interface application in an automated system can be estimated by quantifying how the reduction in user’s response time to critical events affects the system reliability and efficiency. For this purpose, the formulae of reliability theory for complex automated systems are used, showing the dependence between the system reliability and user’s response time to critical event.

Inter comparison of REPAS and APSRA methodologies for passive system reliability analysis

International Nuclear Information System (INIS)

Solanki, R.B.; Krishnamurthy, P.R.; Singh, Suneet; Varde, P.V.; Verma, A.K.

2014-01-01

methods. These procedures can then be applied for evaluating passive system reliability, which would be used in risk-informed decision-making. (author)

System reliability developments in structural engineering

International Nuclear Information System (INIS)

Moses, F.

1982-01-01

Two major limitations occur in present structural design code developments utilizing reliability theory. The notional system reliabilities may differ significantly from calibrated component reliabilities. Secondly, actual failures are often due to gross errors not reflected in most present code formats. A review is presented of system reliability methods and further new concepts are developed. The incremental load approach for identifying and expressing collapse modes is expanded by employing a strategy to identify and enumerate the significant structural collapse modes. It further isolates the importance of critical components in the system performance. Ductile and brittle component behavior and strength correlation is reflected in the system model and illustrated in several examples. Modal combinations for the system reliability are also reviewed. From these developments a system factor can be addended to component safety checking equations. Values may be derived from system behavior by substituting in a damage model which accounts for the response range from component failure to collapse. Other strategies are discussed which emphasize quality assurance during design and in-service inspection for components whose behavior is critical to the system reliability. (Auth.)

Reliability of electronic systems

International Nuclear Information System (INIS)

Roca, Jose L.

2001-01-01

Reliability techniques have been developed subsequently as a need of the diverse engineering disciplines, nevertheless they are not few those that think they have been work a lot on reliability before the same word was used in the current context. Military, space and nuclear industries were the first ones that have been involved in this topic, however not only in these environments it is that it has been carried out this small great revolution in benefit of the increase of the reliability figures of the products of those industries, but rather it has extended to the whole industry. The fact of the massive production, characteristic of the current industries, drove four decades ago, to the fall of the reliability of its products, on one hand, because the massively itself and, for other, to the recently discovered and even not stabilized industrial techniques. Industry should be changed according to those two new requirements, creating products of medium complexity and assuring an enough reliability appropriated to production costs and controls. Reliability began to be integral part of the manufactured product. Facing this philosophy, the book describes reliability techniques applied to electronics systems and provides a coherent and rigorous framework for these diverse activities providing a unifying scientific basis for the entire subject. It consists of eight chapters plus a lot of statistical tables and an extensive annotated bibliography. Chapters embrace the following topics: 1- Introduction to Reliability; 2- Basic Mathematical Concepts; 3- Catastrophic Failure Models; 4-Parametric Failure Models; 5- Systems Reliability; 6- Reliability in Design and Project; 7- Reliability Tests; 8- Software Reliability. This book is in Spanish language and has a potentially diverse audience as a text book from academic to industrial courses. (author)

Social sensing building reliable systems on unreliable data

CERN Document Server

Wang, Dong; Kaplan, Lance

2015-01-01

Increasingly, human beings are sensors engaging directly with the mobile Internet. Individuals can now share real-time experiences at an unprecedented scale. Social Sensing: Building Reliable Systems on Unreliable Data looks at recent advances in the emerging field of social sensing, emphasizing the key problem faced by application designers: how to extract reliable information from data collected from largely unknown and possibly unreliable sources. The book explains how a myriad of societal applications can be derived from this massive amount of data collected and shared by average individu

A reliable sewage quality abnormal event monitoring system.

Science.gov (United States)

Li, Tianling; Winnel, Melissa; Lin, Hao; Panther, Jared; Liu, Chang; O'Halloran, Roger; Wang, Kewen; An, Taicheng; Wong, Po Keung; Zhang, Shanqing; Zhao, Huijun

2017-09-15

With closing water loop through purified recycled water, wastewater becomes a part of source water, requiring reliable wastewater quality monitoring system (WQMS) to manage wastewater source and mitigate potential health risks. However, the development of reliable WQMS is fatally constrained by severe contamination and biofouling of sensors due to the hostile analytical environment of wastewaters, especially raw sewages, that challenges the limit of existing sensing technologies. In this work, we report a technological solution to enable the development of WQMS for real-time abnormal event detection with high reliability and practicality. A vectored high flow hydrodynamic self-cleaning approach and a dual-sensor self-diagnostic concept are adopted for WQMS to effectively encounter vital sensor failing issues caused by contamination and biofouling and ensure the integrity of sensing data. The performance of the WQMS has been evaluated over a 3-year trial period at different sewage catchment sites across three Australian states. It has demonstrated that the developed WQMS is capable of continuously operating in raw sewage for a prolonged period up to 24 months without maintenance and failure, signifying the high reliability and practicality. The demonstrated WQMS capability to reliably acquire real-time wastewater quality information leaps forward the development of effective wastewater source management system. The reported self-cleaning and self-diagnostic concepts should be applicable to other online water quality monitoring systems, opening a new way to encounter the common reliability and stability issues caused by sensor contamination and biofouling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Plant Reliability - an Integrated System for Management (PR-ISM)

International Nuclear Information System (INIS)

Aukeman, M.C.; Leininger, E.G.; Carr, P.

1984-01-01

The Toledo Edison Company, located in Toledo, Ohio, United States of America, recently implemented a comprehensive maintenance management information system for the Davis-Besse Nuclear Power Station. The system is called PR-ISM, meaning Plant Reliability - An Integrated System for Management. PR-ISM provides the tools needed by station management to effectively plan and control maintenance and other plant activities. The PR-ISM system as it exists today consists of four integrated computer applications: equipment data base maintenance, maintenance work order control, administrative activity tracking, and technical specification compliance. PR-ISM is designed as an integrated on-line system and incorporates strong human factors features. PR-ISM provides each responsible person information to do his job on a daily basis and to look ahead towards future events. It goes beyond 'after the fact' reporting. In this respect, PR-ISM is an 'interactive' control system which: captures work requirements and commitments as they are identified, provides accurate and up-to-date status immediately to those who need it, simplifies paperwork and reduces the associated time delays, provides the information base for work management and reliability analysis, and improves productivity by replacing clerical tasks and consolidating maintenance activities. The functional and technical features of PR-ISM, the experience of Toledo Edison during the first year of operation, and the factors which led to the success of the development project are highlighted. (author)

The REPAS approach to the evaluation of passive safety systems reliability

International Nuclear Information System (INIS)

Bianchi, F.; Burgazzi, L.; D'Auria, F.; Ricotti, M.E.

2002-01-01

Scope of this research, carried out by ENEA in collaboration with University of Pisa and Polytechnic of Milano since 1999, is the identification of a methodology allowing the evaluation of the reliability of passive systems as a whole, in a more physical and phenomenal way. The paper describe the study, named REPAS (Reliability Evaluation of Passive Safety systems), carried out by the partners and finalised to the development and validation of such a procedure. The strategy of engagement moves from the consideration that a passive system should be theoretically more reliable than an active one. In fact it does not need any external input or energy to operate and it relies only upon natural physical laws (e.g. gravity, natural circulation, internally stored energy, etc.) and/or 'intelligent' use of the energy inherently available in the system (e.g. chemical reaction, decay heat, etc.). Nevertheless the passive system may fail its mission not only as a consequence of classical mechanical failure of components, but also for deviation from the expected behaviour, due to physical phenomena mainly related to thermal-hydraulics or due to different boundary and initial conditions. The main sources of physical failure are identified and a probability of occurrence is assigned. The reliability analysis is performed on a passive system which operates in two-phase, natural circulation. The selected system is a loop including a heat source and a heat sink where the condensation occurs. The system behaviour under different configurations has been simulated via best-estimate code (Relap5 mod3.2). The results are shown and can be treated in such a way to give qualitative and quantitative information on the system reliability. Main routes of development of the methodology are also depicted. The analysis of the results shows that the procedure is suitable to evaluate the performance of a passive system on a probabilistic / deterministic basis. Important information can also be

Exploitation examination of reliability of coal dust systems

International Nuclear Information System (INIS)

Dojchinovski, Ilija; Trajkovski, Kole

1997-01-01

Designers and operators wish is, long, failure free operation at designed parameters of every system. Always we know the system start up time, but we don't know how long this system will operate successfully. Because of that in this article is given a method how, step by step, to determine the reliability of the system. Reliability parameters are obtained from experimental and operational data. When reliability parameters are determined then it is very easy to compare reliability of similar systems, for example excavators, or different systems, such as truck and rubber band transport system. Practical use of the theory of reliability is by purchasing of the systems when manufacturers have to have and present reliability parameters and on this way we can decide which system satisfies our needs regarding the quality-price-reliability. Reliability can be practically used in system operation where: 1) system reliability is maintained with proper start, use and shutdown of the system; 2) a system reliability is maintained with good maintenance organization; 3) a system reliability is maintained with innovations and improvements with final purpose removing of the imperfections experienced through the operation. Reliability is very important parameter in power generation plants. (Author)

GStat 2.0: Grid Information System Status Monitoring

International Nuclear Information System (INIS)

Field, Laurence; Huang, Joanna; Tsai, Min

2010-01-01

Grid Information Systems are mission-critical components in today's production grid infrastructures. They enable users, applications and services to discover which services exist in the infrastructure and further information about the service structure and state. It is therefore important that the information system components themselves are functioning correctly and that the information content is reliable. Grid Status (GStat) is a tool that monitors the structural integrity of the EGEE information system, which is a hierarchical system built out of more than 260 site-level and approximately 70 global aggregation services. It also checks the information content and presents summary and history displays for Grid Operators and System Administrators. A major new version, GStat 2.0, aims to build on the production experience of GStat and provides additional functionality, which enables it to be extended and combined with other tools. This paper describes the new architecture used for GStat 2.0 and how it can be used at all levels to help provide a reliable information system.

Conceptual Software Reliability Prediction Models for Nuclear Power Plant Safety Systems

International Nuclear Information System (INIS)

Johnson, G.; Lawrence, D.; Yu, H.

2000-01-01

of the individual hardware/software components. Existing modeling techniques--such as fault tree analyses or reliability block diagrams--can probably be adapted to bridge the gaps between the reliability of the hardware components, the individual software elements, and the overall digital system. This project builds upon previous work to survey and rank potential measurement methods which could be used to measure software product reliability 3. This survey and ranking identified candidate measures for use in predicting the reliability of digital computer-based control and protection systems for nuclear power plants. Additionally, information gleaned from the study can be used to supplement existing review methods during an assessment of software-based digital systems

Completeness and reliability of mortality data in Viet Nam: Implications for the national routine health management information system.

Science.gov (United States)

Hong, Tran Thi; Phuong Hoa, Nguyen; Walker, Sue M; Hill, Peter S; Rao, Chalapati

2018-01-01

Mortality statistics form a crucial component of national Health Management Information Systems (HMIS). However, there are limitations in the availability and quality of mortality data at national level in Viet Nam. This study assessed the completeness of recorded deaths and the reliability of recorded causes of death (COD) in the A6 death registers in the national routine HMIS in Viet Nam. 1477 identified deaths in 2014 were reviewed in two provinces. A capture-recapture method was applied to assess the completeness of the A6 death registers. 1365 household verbal autopsy (VA) interviews were successfully conducted, and these were reviewed by physicians who assigned multiple and underlying cause of death (UCOD). These UCODs from VA were then compared with the CODs recorded in the A6 death registers, using kappa scores to assess the reliability of the A6 death register diagnoses. The overall completeness of the A6 death registers in the two provinces was 89.3% (95%CI: 87.8-90.8). No COD recorded in the A6 death registers demonstrated good reliability. There is very low reliability in recording of cardiovascular deaths (kappa for stroke = 0.47 and kappa for ischaemic heart diseases = 0.42) and diabetes (kappa = 0.33). The reporting of deaths due to road traffic accidents, HIV and some cancers are at a moderate level of reliability with kappa scores ranging between 0.57-0.69 (pViet Nam.

Least-cost failure diagnosis in uncertain reliability systems

International Nuclear Information System (INIS)

Cox, Louis Anthony; Chiu, Steve Y.; Sun Xiaorong

1996-01-01

In many textbook solutions, for systems failure diagnosis problems studied using reliability theory and artificial intelligence, the prior probabilities of different failure states can be estimated and used to guide the sequential search for failed components after the whole system fails. In practice, however, both the component failure probabilities and the structure function of the system being examined--i.e., the mapping between the states of its components and the state of the system--may not be known with certainty. At best:, the probabilities of different hypothesized system descriptions, each specifying the component failure probabilities and the system's structure function, may be known to a useful approximation, perhaps based on sample data and previous experience. Cost-effective diagnosis of the system's failure state is then a challenging problem. Although the probabilities of component failures are aleatory, uncertainties about these probabilities and about the system structure function are epistemic. This paper examines how to make best use of both epistemic prior probabilities for system descriptions and the information gleaned from costly inspections of component states after the system fails, to minimize the average cost of identifying the failure state. Two approaches are introduced for systems dominated by aleatory uncertainties, one motivated by information theory and the other based on the idea of trying to prove a hypothesis about the identity of the failure state as efficiently as possible. While the general problem of cost-effective failure diagnosis is computationally intractable (NP-hard), both heuristics provide useful approximations on small to moderate sized problems and optimal results for certain common types of reliability systems, including series, parallel, parallel-series, and k-out-of-n systems. A hybrid heuristic that adaptively chooses which heuristic to apply next after any sequence of observations (component test results

Advances in reliability and system engineering

CERN Document Server

Davim, J

2017-01-01

This book presents original studies describing the latest research and developments in the area of reliability and systems engineering. It helps the reader identifying gaps in the current knowledge and presents fruitful areas for further research in the field. Among others, this book covers reliability measures, reliability assessment of multi-state systems, optimization of multi-state systems, continuous multi-state systems, new computational techniques applied to multi-state systems and probabilistic and non-probabilistic safety assessment.

Reliability of large and complex systems

CERN Document Server

Kolowrocki, Krzysztof

2014-01-01

Reliability of Large and Complex Systems, previously titled Reliability of Large Systems, is an innovative guide to the current state and reliability of large and complex systems. In addition to revised and updated content on the complexity and safety of large and complex mechanisms, this new edition looks at the reliability of nanosystems, a key research topic in nanotechnology science. The author discusses the importance of safety investigation of critical infrastructures that have aged or have been exposed to varying operational conditions. This reference provides an asympt

System evaluations by means of reliability analyses

International Nuclear Information System (INIS)

Breiling, G.

1976-01-01

The objective of this study is to show which analysis requirements are associated with the claim that a reliability analysis, as practised at present, can provide a quantitative risk assessment in absolute terms. The question arises of whether this claim can be substantiated without direct access to the specialist technical departments of a manufacturer and to the multifarious detail information available in these departments. The individual problems arising in the course of such an analysis are discussed on the example of a reliability analysis of a core flooding system. The questions discussed relate to analysis organisation, sequence analysis, fault-tree analysis, and the treatment of operational processes superimposed on the failure and repair processes. (orig.) [de

Power system reliability memento; Memento de la surete du systeme electrique

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-07-01

The reliability memento of the French power system (national power transmission grid) is an educational document which purpose is to point out the role of each one as regards power system operating reliability. This memento was first published in 1999. Extensive changes have taken place since then. The new 2002 edition shows that system operating reliability is as an important subject as ever: 1 - foreword; 2 - system reliability: the basics; 3 - equipment measures taken in order to guarantee the reliability of the system; 4 - organisational and human measures taken to guarantee the reliability of the system; appendix 1 - system operation: basic concepts; appendix 2 - guiding principles governing the reliability of the power system; appendix 3 - international associations of transmission system operators; appendix 4 - description of major incidents.

Reliability evaluation of power systems

CERN Document Server

Billinton, Roy

1996-01-01

The Second Edition of this well-received textbook presents over a decade of new research in power system reliability-while maintaining the general concept, structure, and style of the original volume. This edition features new chapters on the growing areas of Monte Carlo simulation and reliability economics. In addition, chapters cover the latest developments in techniques and their application to real problems. The text also explores the progress occurring in the structure, planning, and operation of real power systems due to changing ownership, regulation, and access. This work serves as a companion volume to Reliability Evaluation of Engineering Systems: Second Edition (1992).

Integrated system reliability analysis

DEFF Research Database (Denmark)

Gintautas, Tomas; Sørensen, John Dalsgaard

Specific targets: 1) The report shall describe the state of the art of reliability and risk-based assessment of wind turbine components. 2) Development of methodology for reliability and risk-based assessment of the wind turbine at system level. 3) Describe quantitative and qualitative measures...

Reliability Based Optimization of Structural Systems

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

1987-01-01

The optimization problem to design structural systems such that the reliability is satisfactory during the whole lifetime of the structure is considered in this paper. Some of the quantities modelling the loads and the strength of the structure are modelled as random variables. The reliability...... is estimated using first. order reliability methods ( FORM ). The design problem is formulated as the optimization problem to minimize a given cost function such that the reliability of the single elements satisfies given requirements or such that the systems reliability satisfies a given requirement....... For these optimization problems it is described how a sensitivity analysis can be performed. Next, new optimization procedures to solve the optimization problems are presented. Two of these procedures solve the system reliability based optimization problem sequentially using quasi-analytical derivatives. Finally...

Waste Information Data System user guide

International Nuclear Information System (INIS)

Dietz, L.A.

1996-09-01

The Waste Information Data System (also known as the Environmental Sites Database) is a computerized system that provides a traceable source of information about environmental waste sites at the U.S. Department of Energy's Hanford Site in Richland, Washington. The system includes discovery, rejected, and accepted waste sites. The purpose of the system is to assist long-range waste management and environmental restoration planning by providing validated and reliable information about waste sites. The system is used to track site investigation, remediation, and closure-action activities

System reliability of corroding pipelines

International Nuclear Information System (INIS)

Zhou Wenxing

2010-01-01

A methodology is presented in this paper to evaluate the time-dependent system reliability of a pipeline segment that contains multiple active corrosion defects and is subjected to stochastic internal pressure loading. The pipeline segment is modeled as a series system with three distinctive failure modes due to corrosion, namely small leak, large leak and rupture. The internal pressure is characterized as a simple discrete stochastic process that consists of a sequence of independent and identically distributed random variables each acting over a period of one year. The magnitude of a given sequence follows the annual maximum pressure distribution. The methodology is illustrated through a hypothetical example. Furthermore, the impact of the spatial variability of the pressure loading and pipe resistances associated with different defects on the system reliability is investigated. The analysis results suggest that the spatial variability of pipe properties has a negligible impact on the system reliability. On the other hand, the spatial variability of the internal pressure, initial defect sizes and defect growth rates can have a significant impact on the system reliability.

Power system reliability analysis using fault trees

International Nuclear Information System (INIS)

Volkanovski, A.; Cepin, M.; Mavko, B.

2006-01-01

The power system reliability analysis method is developed from the aspect of reliable delivery of electrical energy to customers. The method is developed based on the fault tree analysis, which is widely applied in the Probabilistic Safety Assessment (PSA). The method is adapted for the power system reliability analysis. The method is developed in a way that only the basic reliability parameters of the analysed power system are necessary as an input for the calculation of reliability indices of the system. The modeling and analysis was performed on an example power system consisting of eight substations. The results include the level of reliability of current power system configuration, the combinations of component failures resulting in a failed power delivery to loads, and the importance factors for components and subsystems. (author)

Reliability Estimation for Digital Instrument/Control System

Energy Technology Data Exchange (ETDEWEB)

Yang, Yaguang; Sydnor, Russell [U.S. Nuclear Regulatory Commission, Washington, D.C. (United States)

2011-08-15

Digital instrumentation and controls (DI and C) systems are widely adopted in various industries because of their flexibility and ability to implement various functions that can be used to automatically monitor, analyze, and control complicated systems. It is anticipated that the DI and C will replace the traditional analog instrumentation and controls (AI and C) systems in all future nuclear reactor designs. There is an increasing interest for reliability and risk analyses for safety critical DI and C systems in regulatory organizations, such as The United States Nuclear Regulatory Commission. Developing reliability models and reliability estimation methods for digital reactor control and protection systems will involve every part of the DI and C system, such as sensors, signal conditioning and processing components, transmission lines and digital communication systems, D/A and A/D converters, computer system, signal processing software, control and protection software, power supply system, and actuators. Some of these components are hardware, such as sensors and actuators, their failure mechanisms are well understood, and the traditional reliability model and estimation methods can be directly applied. But many of these components are firmware which has software embedded in the hardware, and software needs special consideration because its failure mechanism is unique, and the reliability estimation method for a software system will be different from the ones used for hardware systems. In this paper, we will propose a reliability estimation method for the entire DI and C system reliability using a recently developed software reliability estimation method and a traditional hardware reliability estimation method.

Reliability Estimation for Digital Instrument/Control System

International Nuclear Information System (INIS)

Yang, Yaguang; Sydnor, Russell

2011-01-01

Digital instrumentation and controls (DI and C) systems are widely adopted in various industries because of their flexibility and ability to implement various functions that can be used to automatically monitor, analyze, and control complicated systems. It is anticipated that the DI and C will replace the traditional analog instrumentation and controls (AI and C) systems in all future nuclear reactor designs. There is an increasing interest for reliability and risk analyses for safety critical DI and C systems in regulatory organizations, such as The United States Nuclear Regulatory Commission. Developing reliability models and reliability estimation methods for digital reactor control and protection systems will involve every part of the DI and C system, such as sensors, signal conditioning and processing components, transmission lines and digital communication systems, D/A and A/D converters, computer system, signal processing software, control and protection software, power supply system, and actuators. Some of these components are hardware, such as sensors and actuators, their failure mechanisms are well understood, and the traditional reliability model and estimation methods can be directly applied. But many of these components are firmware which has software embedded in the hardware, and software needs special consideration because its failure mechanism is unique, and the reliability estimation method for a software system will be different from the ones used for hardware systems. In this paper, we will propose a reliability estimation method for the entire DI and C system reliability using a recently developed software reliability estimation method and a traditional hardware reliability estimation method

Analysis of Parking Reliability Guidance of Urban Parking Variable Message Sign System

Directory of Open Access Journals (Sweden)

Zhenyu Mei

2012-01-01

Full Text Available Operators of parking guidance and information systems (PGIS often encounter difficulty in determining when and how to provide reliable car park availability information to drivers. Reliability has become a key factor to ensure the benefits of urban PGIS. The present paper is the first to define the guiding parking reliability of urban parking variable message signs (VMSs. By analyzing the parking choice under guiding and optional parking lots, a guiding parking reliability model was constructed. A mathematical program was formulated to determine the guiding parking reliability of VMS. The procedures were applied to a numerical example, and the factors that affect guiding reliability were analyzed. The quantitative changes of the parking berths and the display conditions of VMS were found to be the most important factors influencing guiding reliability. The parking guiding VMS achieved the best benefit when the parking supply was close to or was less than the demand. The combination of a guiding parking reliability model and parking choice behavior offers potential for PGIS operators to reduce traffic congestion in central city areas.

The reliability-quality relationship for quality systems and quality risk management.

Science.gov (United States)

Claycamp, H Gregg; Rahaman, Faiad; Urban, Jason M

2012-01-01

Engineering reliability typically refers to the probability that a system, or any of its components, will perform a required function for a stated period of time and under specified operating conditions. As such, reliability is inextricably linked with time-dependent quality concepts, such as maintaining a state of control and predicting the chances of losses from failures for quality risk management. Two popular current good manufacturing practice (cGMP) and quality risk management tools, failure mode and effects analysis (FMEA) and root cause analysis (RCA) are examples of engineering reliability evaluations that link reliability with quality and risk. Current concepts in pharmaceutical quality and quality management systems call for more predictive systems for maintaining quality; yet, the current pharmaceutical manufacturing literature and guidelines are curiously silent on engineering quality. This commentary discusses the meaning of engineering reliability while linking the concept to quality systems and quality risk management. The essay also discusses the difference between engineering reliability and statistical (assay) reliability. The assurance of quality in a pharmaceutical product is no longer measured only "after the fact" of manufacturing. Rather, concepts of quality systems and quality risk management call for designing quality assurance into all stages of the pharmaceutical product life cycle. Interestingly, most assays for quality are essentially static and inform product quality over the life cycle only by being repeated over time. Engineering process reliability is the fundamental concept that is meant to anticipate quality failures over the life cycle of the product. Reliability is a well-developed theory and practice for other types of manufactured products and manufacturing processes. Thus, it is well known to be an appropriate index of manufactured product quality. This essay discusses the meaning of reliability and its linkages with quality

Reliability-Based Optimization of Series Systems of Parallel Systems

DEFF Research Database (Denmark)

Enevoldsen, I.; Sørensen, John Dalsgaard

Reliability-based design of structural systems is considered. Especially systems where the reliability model is a series system of parallel systems are analysed. A sensitivity analysis for this class of problems is presented. Direct and sequential optimization procedures to solve the optimization...

System Reliability Analysis Considering Correlation of Performances

Energy Technology Data Exchange (ETDEWEB)

Kim, Saekyeol; Lee, Tae Hee [Hanyang Univ., Seoul (Korea, Republic of); Lim, Woochul [Mando Corporation, Seongnam (Korea, Republic of)

2017-04-15

Reliability analysis of a mechanical system has been developed in order to consider the uncertainties in the product design that may occur from the tolerance of design variables, uncertainties of noise, environmental factors, and material properties. In most of the previous studies, the reliability was calculated independently for each performance of the system. However, the conventional methods cannot consider the correlation between the performances of the system that may lead to a difference between the reliability of the entire system and the reliability of the individual performance. In this paper, the joint probability density function (PDF) of the performances is modeled using a copula which takes into account the correlation between performances of the system. The system reliability is proposed as the integral of joint PDF of performances and is compared with the individual reliability of each performance by mathematical examples and two-bar truss example.

System Reliability Analysis Considering Correlation of Performances

International Nuclear Information System (INIS)

Kim, Saekyeol; Lee, Tae Hee; Lim, Woochul

2017-01-01

Reliability analysis of a mechanical system has been developed in order to consider the uncertainties in the product design that may occur from the tolerance of design variables, uncertainties of noise, environmental factors, and material properties. In most of the previous studies, the reliability was calculated independently for each performance of the system. However, the conventional methods cannot consider the correlation between the performances of the system that may lead to a difference between the reliability of the entire system and the reliability of the individual performance. In this paper, the joint probability density function (PDF) of the performances is modeled using a copula which takes into account the correlation between performances of the system. The system reliability is proposed as the integral of joint PDF of performances and is compared with the individual reliability of each performance by mathematical examples and two-bar truss example.

76 FR 42534 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits; System...

Science.gov (United States)

2011-07-19

... Reliability Operating Limits; System Restoration Reliability Standards AGENCY: Federal Energy Regulatory... data necessary to analyze and monitor Interconnection Reliability Operating Limits (IROL) within its... Interconnection Reliability Operating Limits, Order No. 748, 134 FERC ] 61,213 (2011). \\2\\ The term ``Wide-Area...

Reliability of the emergency ac-power system at nuclear power plants

International Nuclear Information System (INIS)

Battle, R.E.; Campbell, D.J.; Baranowsky, P.W.

1982-01-01

The reliability of the emergency ac-power systems typical of several nuclear power plants was estimated, the costs of several possible improvements was estimated. Fault trees were constructed based on a detailed design review of the emergency ac-power systems of 18 nuclear plants. The failure probabilities used in the fault trees were calculated from extensive historical data collected from Licensee Event Reports (LERs) and from operating experience information obtained from nuclear plant licensees. It was found that there are not one or two improvements that can be made at all plants to significantly increase the industry-average emergency ac-power-system reliability, but the improvements are varied and plant-specific. Estimates of the improvements in reliability and the associated cost are estimated using plant-specific designs and failure probabilities

Reliability models for Space Station power system

Science.gov (United States)

Singh, C.; Patton, A. D.; Kim, Y.; Wagner, H.

1987-01-01

This paper presents a methodology for the reliability evaluation of Space Station power system. The two options considered are the photovoltaic system and the solar dynamic system. Reliability models for both of these options are described along with the methodology for calculating the reliability indices.

Reliability-Based Decision Fusion in Multimodal Biometric Verification Systems

Directory of Open Access Journals (Sweden)

Kryszczuk Krzysztof

2007-01-01

Full Text Available We present a methodology of reliability estimation in the multimodal biometric verification scenario. Reliability estimation has shown to be an efficient and accurate way of predicting and correcting erroneous classification decisions in both unimodal (speech, face, online signature and multimodal (speech and face systems. While the initial research results indicate the high potential of the proposed methodology, the performance of the reliability estimation in a multimodal setting has not been sufficiently studied or evaluated. In this paper, we demonstrate the advantages of using the unimodal reliability information in order to perform an efficient biometric fusion of two modalities. We further show the presented method to be superior to state-of-the-art multimodal decision-level fusion schemes. The experimental evaluation presented in this paper is based on the popular benchmarking bimodal BANCA database.

Reliable actuators for twin rotor MIMO system

Science.gov (United States)

Rao, Vidya S.; V. I, George; Kamath, Surekha; Shreesha, C.

2017-11-01

Twin Rotor MIMO System (TRMS) is a bench mark system to test flight control algorithms. One of the perturbations on TRMS which is likely to affect the control system is actuator failure. Therefore, there is a need for a reliable control system, which includes H infinity controller along with redundant actuators. Reliable control refers to the design of a control system to tolerate failures of a certain set of actuators or sensors while retaining desired control system properties. Output of reliable controller has to be transferred to the redundant actuator effectively to make the TRMS reliable even under actual actuator failure.

RELIABILITY ANALYSIS OF POWER DISTRIBUTION SYSTEMS

Directory of Open Access Journals (Sweden)

Popescu V.S.

2012-04-01

Full Text Available Power distribution systems are basic parts of power systems and reliability of these systems at present is a key issue for power engineering development and requires special attention. Operation of distribution systems is accompanied by a number of factors that produce random data a large number of unplanned interruptions. Research has shown that the predominant factors that have a significant influence on the reliability of distribution systems are: weather conditions (39.7%, defects in equipment(25% and unknown random factors (20.1%. In the article is studied the influence of random behavior and are presented estimations of reliability of predominantly rural electrical distribution systems.

An automated method for estimating reliability of grid systems using Bayesian networks

International Nuclear Information System (INIS)

Doguc, Ozge; Emmanuel Ramirez-Marquez, Jose

2012-01-01

Grid computing has become relevant due to its applications to large-scale resource sharing, wide-area information transfer, and multi-institutional collaborating. In general, in grid computing a service requests the use of a set of resources, available in a grid, to complete certain tasks. Although analysis tools and techniques for these types of systems have been studied, grid reliability analysis is generally computation-intensive to obtain due to the complexity of the system. Moreover, conventional reliability models have some common assumptions that cannot be applied to the grid systems. Therefore, new analytical methods are needed for effective and accurate assessment of grid reliability. This study presents a new method for estimating grid service reliability, which does not require prior knowledge about the grid system structure unlike the previous studies. Moreover, the proposed method does not rely on any assumptions about the link and node failure rates. This approach is based on a data-mining algorithm, the K2, to discover the grid system structure from raw historical system data, that allows to find minimum resource spanning trees (MRST) within the grid then, uses Bayesian networks (BN) to model the MRST and estimate grid service reliability.

Algorithms for Bayesian network modeling and reliability assessment of infrastructure systems

International Nuclear Information System (INIS)

Tien, Iris; Der Kiureghian, Armen

2016-01-01

Novel algorithms are developed to enable the modeling of large, complex infrastructure systems as Bayesian networks (BNs). These include a compression algorithm that significantly reduces the memory storage required to construct the BN model, and an updating algorithm that performs inference on compressed matrices. These algorithms address one of the major obstacles to widespread use of BNs for system reliability assessment, namely the exponentially increasing amount of information that needs to be stored as the number of components in the system increases. The proposed compression and inference algorithms are described and applied to example systems to investigate their performance compared to that of existing algorithms. Orders of magnitude savings in memory storage requirement are demonstrated using the new algorithms, enabling BN modeling and reliability analysis of larger infrastructure systems. - Highlights: • Novel algorithms developed for Bayesian network modeling of infrastructure systems. • Algorithm presented to compress information in conditional probability tables. • Updating algorithm presented to perform inference on compressed matrices. • Algorithms applied to example systems to investigate their performance. • Orders of magnitude savings in memory storage requirement demonstrated.

Towards Reliable Integrated Services for Dependable Systems

DEFF Research Database (Denmark)

Schiøler, Henrik; Ravn, Anders Peter; Izadi-Zamanabadi, Roozbeh

Reliability issues for various technical systems are discussed and focus is directed towards distributed systems, where communication facilities are vital to maintain system functionality. Reliability in communication subsystems is considered as a resource to be shared among a number of logical c...... applications residing on alternative routes. Details are provided for the operation of RRRSVP based on reliability slack calculus. Conclusions summarize the considerations and give directions for future research....... connections and a reliability management framework is suggested. We suggest a network layer level reliability management protocol RRSVP (Reliability Resource Reservation Protocol) as a counterpart of the RSVP for bandwidth and time resource management. Active and passive standby redundancy by background...

Towards Reliable Integrated Services for Dependable Systems

DEFF Research Database (Denmark)

Schiøler, Henrik; Ravn, Anders Peter; Izadi-Zamanabadi, Roozbeh

2003-01-01

Reliability issues for various technical systems are discussed and focus is directed towards distributed systems, where communication facilities are vital to maintain system functionality. Reliability in communication subsystems is considered as a resource to be shared among a number of logical c...... applications residing on alternative routes. Details are provided for the operation of RRRSVP based on reliability slack calculus. Conclusions summarize the considerations and give directions for future research....... connections and a reliability management framework is suggested. We suggest a network layer level reliability management protocol RRSVP (Reliability Resource Reservation Protocol) as a counterpart of the RSVP for bandwidth and time resource management. Active and passive standby redundancy by background...

Bulk electric system reliability evaluation incorporating wind power and demand side management

Science.gov (United States)

Huang, Dange

Electric power systems are experiencing dramatic changes with respect to structure, operation and regulation and are facing increasing pressure due to environmental and societal constraints. Bulk electric system reliability is an important consideration in power system planning, design and operation particularly in the new competitive environment. A wide range of methods have been developed to perform bulk electric system reliability evaluation. Theoretically, sequential Monte Carlo simulation can include all aspects and contingencies in a power system and can be used to produce an informative set of reliability indices. It has become a practical and viable tool for large system reliability assessment technique due to the development of computing power and is used in the studies described in this thesis. The well-being approach used in this research provides the opportunity to integrate an accepted deterministic criterion into a probabilistic framework. This research work includes the investigation of important factors that impact bulk electric system adequacy evaluation and security constrained adequacy assessment using the well-being analysis framework. Load forecast uncertainty is an important consideration in an electrical power system. This research includes load forecast uncertainty considerations in bulk electric system reliability assessment and the effects on system, load point and well-being indices and reliability index probability distributions are examined. There has been increasing worldwide interest in the utilization of wind power as a renewable energy source over the last two decades due to enhanced public awareness of the environment. Increasing penetration of wind power has significant impacts on power system reliability, and security analyses become more uncertain due to the unpredictable nature of wind power. The effects of wind power additions in generating and bulk electric system reliability assessment considering site wind speed

System principles, mathematical models and methods to ensure high reliability of safety systems

Science.gov (United States)

Zaslavskyi, V.

2017-04-01

Modern safety and security systems are composed of a large number of various components designed for detection, localization, tracking, collecting, and processing of information from the systems of monitoring, telemetry, control, etc. They are required to be highly reliable in a view to correctly perform data aggregation, processing and analysis for subsequent decision making support. On design and construction phases of the manufacturing of such systems a various types of components (elements, devices, and subsystems) are considered and used to ensure high reliability of signals detection, noise isolation, and erroneous commands reduction. When generating design solutions for highly reliable systems a number of restrictions and conditions such as types of components and various constrains on resources should be considered. Various types of components perform identical functions; however, they are implemented using diverse principles, approaches and have distinct technical and economic indicators such as cost or power consumption. The systematic use of different component types increases the probability of tasks performing and eliminates the common cause failure. We consider type-variety principle as an engineering principle of system analysis, mathematical models based on this principle, and algorithms for solving optimization problems of highly reliable safety and security systems design. Mathematical models are formalized in a class of two-level discrete optimization problems of large dimension. The proposed approach, mathematical models, algorithms can be used for problem solving of optimal redundancy on the basis of a variety of methods and control devices for fault and defects detection in technical systems, telecommunication networks, and energy systems.

Component reliability for electronic systems

CERN Document Server

Bajenescu, Titu-Marius I

2010-01-01

The main reason for the premature breakdown of today's electronic products (computers, cars, tools, appliances, etc.) is the failure of the components used to build these products. Today professionals are looking for effective ways to minimize the degradation of electronic components to help ensure longer-lasting, more technically sound products and systems. This practical book offers engineers specific guidance on how to design more reliable components and build more reliable electronic systems. Professionals learn how to optimize a virtual component prototype, accurately monitor product reliability during the entire production process, and add the burn-in and selection procedures that are the most appropriate for the intended applications. Moreover, the book helps system designers ensure that all components are correctly applied, margins are adequate, wear-out failure modes are prevented during the expected duration of life, and system interfaces cannot lead to failure.

Personalised Information Gathering and Recommender Systems: Techniques and Trends

Directory of Open Access Journals (Sweden)

Xiaohui Tao

2013-02-01

Full Text Available With the explosive growth of resources available through the Internet, information mismatching and overload have become a severe concern to users.Web users are commonly overwhelmed by huge volume of information and are faced with the challenge of finding the most relevant and reliable information in a timely manner. Personalised information gathering and recommender systems represent state-of-the-art tools for efficient selection of the most relevant and reliable information resources, and the interest in such systems has increased dramatically over the last few years. However, web personalization has not yet been well-exploited; difficulties arise while selecting resources through recommender systems from a technological and social perspective. Aiming to promote high quality research in order to overcome these challenges, this paper provides a comprehensive survey on the recent work and achievements in the areas of personalised web information gathering and recommender systems. The report covers concept-based techniques exploited in personalised information gathering and recommender systems.

Failure and Maintenance Analysis Using Web-Based Reliability Database System

International Nuclear Information System (INIS)

Hwang, Seok Won; Kim, Myoung Su; Seong, Ki Yeoul; Na, Jang Hwan; Jerng, Dong Wook

2007-01-01

Korea Hydro and Nuclear Power Company has lunched the development of a database system for PSA and Maintenance Rule implementation. It focuses on the easy processing of raw data into a credible and useful database for the risk-informed environment of nuclear power plant operation and maintenance. Even though KHNP had recently completed the PSA for all domestic NPPs as a requirement of the severe accident mitigation strategy, the component failure data were only gathered as a means of quantification purposes for the relevant project. So, the data were not efficient enough for the Living PSA or other generic purposes. Another reason to build a real time database is for the newly adopted Maintenance Rule, which requests the utility to continuously monitor the plant risk based on its operation and maintenance performance. Furthermore, as one of the pre-condition for the Risk Informed Regulation and Application, the nuclear regulatory agency of Korea requests the development and management of domestic database system. KHNP is stacking up data of operation and maintenance on the Enterprise Resource Planning (ERP) system since its first opening on July, 2003. But, so far a systematic review has not been performed to apply the component failure and maintenance history for PSA and other reliability analysis. The data stored in PUMAS before the ERP system is introduced also need to be converted and managed into the new database structure and methodology. This reliability database system is a web-based interface on a UNIX server with Oracle relational database. It is designed to be applicable for all domestic NPPs with a common database structure and the web interfaces, therefore additional program development would not be necessary for data acquisition and processing in the near future. Categorization standards for systems and components have been implemented to analyze all domestic NPPs. For example, SysCode (for a system code) and CpCode (for a component code) were newly

ACCURACY AND RELIABILITY AS CRITERIA OF INFORMATIVENESS IN THE NEWS STORY

Directory of Open Access Journals (Sweden)

Melnikova Ekaterina Aleksandrovna

2014-12-01

Full Text Available The article clarifies the meaning of the terms accuracy and reliability of the news story, offers a researcher's approach to obtaining objective data that helps to verify linguistic means of accuracy and reliability presence in the informative structure of the text. The accuracy of the news story is defined as a high relevance degree of event reflection through language representation of its constituents; the reliability is viewed as news story originality that is proved by introducing citations and sources of information considered being trustworthy into the text content. Having based the research on an event nominative density identification method, the author composed nominative charts of 115 news story texts, collected at web-sites of BBC and CNN media corporations; distinguished qualitative and quantitative markers of accuracy and reliability in the news story text; confirmed that the accuracy of the news story is achieved with terminological clearness in nominating event constituents in the text, thematic bind between words, presence of onyms that help deeply identify characteristics of the referent event. The reliability of the text is discovered in eyewitness accounts, quotations, and references to the sources being considered as trustworthy. Accurate revision of associations between accuracy and reliability and informing strategies in digital news nets allowed the author to set two variants of information delivery, that differ in their communicative and pragmatic functions: developing (that informs about major and minor details of an event and truncated (which gives some details thus raising the interest to the event and urging a reader to open a full story.

Aviation Fuel System Reliability and Fail-Safety Analysis. Promising Alternative Ways for Improving the Fuel System Reliability

Directory of Open Access Journals (Sweden)

I. S. Shumilov

2017-01-01

Full Text Available The paper deals with design requirements for an aviation fuel system (AFS, AFS basic design requirements, reliability, and design precautions to avoid AFS failure. Compares the reliability and fail-safety of AFS and aircraft hydraulic system (AHS, considers the promising alternative ways to raise reliability of fuel systems, as well as elaborates recommendations to improve reliability of the pipeline system components and pipeline systems, in general, based on the selection of design solutions.It is extremely advisable to design the AFS and AHS in accordance with Aviation Regulations АП25 and Accident Prevention Guidelines, ICAO (International Civil Aviation Association, which will reduce risk of emergency situations, and in some cases even avoid heavy disasters.ATS and AHS designs should be based on the uniform principles to ensure the highest reliability and safety. However, currently, this principle is not enough kept, and AFS looses in reliability and fail-safety as compared with AHS. When there are the examined failures (single and their combinations the guidelines to ensure the AFS efficiency should be the same as those of norm-adopted in the Regulations АП25 for AHS. This will significantly increase reliability and fail-safety of the fuel systems and aircraft flights, in general, despite a slight increase in AFS mass.The proposed improvements through the use of components redundancy of the fuel system will greatly raise reliability of the fuel system of a passenger aircraft, which will, without serious consequences for the flight, withstand up to 2 failures, its reliability and fail-safety design will be similar to those of the AHS, however, above improvement measures will lead to a slightly increasing total mass of the fuel system.It is advisable to set a second pump on the engine in parallel with the first one. It will run in case the first one fails for some reasons. The second pump, like the first pump, can be driven from the

Reliability and protection against failure in computer systems

International Nuclear Information System (INIS)

Daniels, B.K.

1979-01-01

Computers are being increasingly integrated into the control and safety systems of large and potentially hazardous industrial processes. This development introduces problems which are particular to computer systems and opens the way to new techniques of solving conventional reliability and availability problems. References to the developing fields of software reliability, human factors and software design are given, and these subjects are related, where possible, to the quantified assessment of reliability. Original material is presented in the areas of reliability growth and computer hardware failure data. The report draws on the experience of the National Centre of Systems Reliability in assessing the capability and reliability of computer systems both within the nuclear industry, and from the work carried out in other industries by the Systems Reliability Service. (author)

On reliability and maintenance modelling of ageing equipment in electric power systems

International Nuclear Information System (INIS)

Lindquist, Tommie

2008-04-01

Maintenance optimisation is essential to achieve cost-efficiency, availability and reliability of supply in electric power systems. The process of maintenance optimisation requires information about the costs of preventive and corrective maintenance, as well as the costs of failures borne by both electricity suppliers and customers. To calculate expected costs, information is needed about equipment reliability characteristics and the way in which maintenance affects equipment reliability. The aim of this Ph.D. work has been to develop equipment reliability models taking the effect of maintenance into account. The research has focussed on the interrelated areas of condition estimation, reliability modelling and maintenance modelling, which have been investigated in a number of case studies. In the area of condition estimation two methods to quantitatively estimate the condition of disconnector contacts have been developed, which utilise results from infrared thermography inspections and contact resistance measurements. The accuracy of these methods were investigated in two case studies. Reliability models have been developed and implemented for SF6 circuit-breakers, disconnector contacts and XLPE cables in three separate case studies. These models were formulated using both empirical and physical modelling approaches. To improve confidence in such models a Bayesian statistical method incorporating information from the equipment design process was also developed. This method was illustrated in a case study of SF6 circuit-breaker operating rods. Methods for quantifying the effect of maintenance on equipment condition and reliability have been investigated in case studies on disconnector contacts and SF6 circuit-breakers. The input required by these methods are condition measurements and historical failure and maintenance data, respectively. This research has demonstrated that the effect of maintenance on power system equipment may be quantified using available data

power system reliability in supplying nuclear reactors

International Nuclear Information System (INIS)

Gad, M.M.M.

2007-01-01

this thesis presents a simple technique for deducing minimal cut set (MCS) from the defined minimal path set (MPS) of generic distribution system and this technique have been used to evaluate the basic reliability indices of Egypt's second research reactor (ETRR-2) electrical distribution network. the alternative system configurations are then studied to evaluate their impact on service reliability. the proposed MCS approach considers both sustained and temporary outage. the temporary outage constitutes an important parameter in characterizing the system reliability indices for critical load point in distribution system. it is also consider the power quality impact on the reliability indices

Exact reliability quantification of highly reliable systems with maintenance

Energy Technology Data Exchange (ETDEWEB)

Bris, Radim, E-mail: radim.bris@vsb.c [VSB-Technical University Ostrava, Faculty of Electrical Engineering and Computer Science, Department of Applied Mathematics, 17. listopadu 15, 70833 Ostrava-Poruba (Czech Republic)

2010-12-15

When a system is composed of highly reliable elements, exact reliability quantification may be problematic, because computer accuracy is limited. Inaccuracy can be due to different aspects. For example, an error may be made when subtracting two numbers that are very close to each other, or at the process of summation of many very different numbers, etc. The basic objective of this paper is to find a procedure, which eliminates errors made by PC when calculations close to an error limit are executed. Highly reliable system is represented by the use of directed acyclic graph which is composed from terminal nodes, i.e. highly reliable input elements, internal nodes representing subsystems and edges that bind all of these nodes. Three admissible unavailability models of terminal nodes are introduced, including both corrective and preventive maintenance. The algorithm for exact unavailability calculation of terminal nodes is based on merits of a high-performance language for technical computing MATLAB. System unavailability quantification procedure applied to a graph structure, which considers both independent and dependent (i.e. repeatedly occurring) terminal nodes is based on combinatorial principle. This principle requires summation of a lot of very different non-negative numbers, which may be a source of an inaccuracy. That is why another algorithm for exact summation of such numbers is designed in the paper. The summation procedure uses benefits from a special number system with the base represented by the value 2{sup 32}. Computational efficiency of the new computing methodology is compared with advanced simulation software. Various calculations on systems from references are performed to emphasize merits of the methodology.

System reliability as perceived by maintenance personnel on petroleum production facilities

International Nuclear Information System (INIS)

Antonovsky, A.; Pollock, C.; Straker, L.

2016-01-01

The aim of this research was to understand the relationship between maintenance staff perceptions of organisational effectiveness and operational reliability in petroleum operations. Engineering measures exist that assess the effectiveness of maintenance and reliability of equipment. These measures are typically retrospective and may not provide insight into what impedes system reliability. Perceptions of organisational effectiveness by the workforce may provide a predictive measure that could improve our understanding of the human factors that influence system reliability. Maintenance personnel (n=133) from nine petroleum production facilities completed a survey as part of a study of human factors and maintenance reliability. 69 respondents (51.9%) provided comments to an open-ended question in the survey, and these data were analysed using Interpretive Phenomenological Analysis to extract themes. Four super-ordinate themes were identified from the analysis: 1) Communication and access to information, 2) Efficiency of current work systems, 3) Need for better workgroup support, and 4) Management impacts on the workplace. We found a significant relationship between the frequency of the four super-ordinate themes and the facility reliability level as measured by ‘Mean Time Between Failures’: χ"2(6,N=158)=16.2, p=.013. These results demonstrated that operational effectiveness might be differentiated on the basis of survey-derived perceptions of maintenance personnel. - Highlights: • Thematic analysis of survey comments provided insights into workplace reliability • Worker’s comments on reliability related to technical data on time between failures • Management decision-making was the main theme in the lower reliability workplaces • Improving efficiency was the main theme in the higher reliability workplaces • Communication and better workgroup support were themes at all reliability levels

Reliability analysis of shutdown system

International Nuclear Information System (INIS)

Kumar, C. Senthil; John Arul, A.; Pal Singh, Om; Suryaprakasa Rao, K.

2005-01-01

This paper presents the results of reliability analysis of Shutdown System (SDS) of Indian Prototype Fast Breeder Reactor. Reliability analysis carried out using Fault Tree Analysis predicts a value of 3.5 x 10 -8 /de for failure of shutdown function in case of global faults and 4.4 x 10 -8 /de for local faults. Based on 20 de/y, the frequency of shutdown function failure is 0.7 x 10 -6 /ry, which meets the reliability target, set by the Indian Atomic Energy Regulatory Board. The reliability is limited by Common Cause Failure (CCF) of actuation part of SDS and to a lesser extent CCF of electronic components. The failure frequency of individual systems is -3 /ry, which also meets the safety criteria. Uncertainty analysis indicates a maximum error factor of 5 for the top event unavailability

Photovoltaic power system reliability considerations

Science.gov (United States)

Lalli, V. R.

1980-01-01

This paper describes an example of how modern engineering and safety techniques can be used to assure the reliable and safe operation of photovoltaic power systems. This particular application was for a solar cell power system demonstration project in Tangaye, Upper Volta, Africa. The techniques involve a definition of the power system natural and operating environment, use of design criteria and analysis techniques, an awareness of potential problems via the inherent reliability and FMEA methods, and use of a fail-safe and planned spare parts engineering philosophy.

Recent Advances in System Reliability Signatures, Multi-state Systems and Statistical Inference

CERN Document Server

Frenkel, Ilia

2012-01-01

Recent Advances in System Reliability discusses developments in modern reliability theory such as signatures, multi-state systems and statistical inference. It describes the latest achievements in these fields, and covers the application of these achievements to reliability engineering practice. The chapters cover a wide range of new theoretical subjects and have been written by leading experts in reliability theory and its applications.  The topics include: concepts and different definitions of signatures (D-spectra),  their  properties and applications  to  reliability of coherent systems and network-type structures; Lz-transform of Markov stochastic process and its application to multi-state system reliability analysis; methods for cost-reliability and cost-availability analysis of multi-state systems; optimal replacement and protection strategy; and statistical inference. Recent Advances in System Reliability presents many examples to illustrate the theoretical results. Real world multi-state systems...

Design for Reliability of Power Electronic Systems

DEFF Research Database (Denmark)

Wang, Huai; Ma, Ke; Blaabjerg, Frede

2012-01-01

Advances in power electronics enable efficient and flexible processing of electric power in the application of renewable energy sources, electric vehicles, adjustable-speed drives, etc. More and more efforts are devoted to better power electronic systems in terms of reliability to ensure high......). A collection of methodologies based on Physics-of-Failure (PoF) approach and mission profile analysis are presented in this paper to perform reliability-oriented design of power electronic systems. The corresponding design procedures and reliability prediction models are provided. Further on, a case study...... on a 2.3 MW wind power converter is discussed with emphasis on the reliability critical components IGBTs. Different aspects of improving the reliability of the power converter are mapped. Finally, the challenges and opportunities to achieve more reliable power electronic systems are addressed....

Solid State Lighting Reliability Components to Systems

CERN Document Server

Fan, XJ

2013-01-01

Solid State Lighting Reliability: Components to Systems begins with an explanation of the major benefits of solid state lighting (SSL) when compared to conventional lighting systems including but not limited to long useful lifetimes of 50,000 (or more) hours and high efficacy. When designing effective devices that take advantage of SSL capabilities the reliability of internal components (optics, drive electronics, controls, thermal design) take on critical importance. As such a detailed discussion of reliability from performance at the device level to sub components is included as well as the integrated systems of SSL modules, lamps and luminaires including various failure modes, reliability testing and reliability performance. This book also: Covers the essential reliability theories and practices for current and future development of Solid State Lighting components and systems Provides a systematic overview for not only the state-of-the-art, but also future roadmap and perspectives of Solid State Lighting r...

A rule induction approach to improve Monte Carlo system reliability assessment

International Nuclear Information System (INIS)

Rocco S, Claudio M.

2003-01-01

A Decision Tree (DT) approach to build empirical models for use in Monte Carlo reliability evaluation is presented. The main idea is to develop an estimation algorithm, by training a model on a restricted data set, and replacing the Evaluation Function (EF) by a simpler calculation, which provides reasonably accurate model outputs. The proposed approach is illustrated with two systems of different size, represented by their equivalent networks. The robustness of the DT approach as an approximated method to replace the EF is also analysed. Excellent system reliability results are obtained by training a DT with a small amount of information

Frontiers of reliability

CERN Document Server

Basu, Asit P; Basu, Sujit K

1998-01-01

This volume presents recent results in reliability theory by leading experts in the world. It will prove valuable for researchers, and users of reliability theory. It consists of refereed invited papers on a broad spectrum of topics in reliability. The subjects covered include Bayesian reliability, Bayesian reliability modeling, confounding in a series system, DF tests, Edgeworth approximation to reliability, estimation under random censoring, fault tree reduction for reliability, inference about changes in hazard rates, information theory and reliability, mixture experiment, mixture of Weibul

Reliability and Cost Impacts for Attritable Systems

Science.gov (United States)

2017-03-23

on reliability and cost: a probabilistic model. Electric Power Systems Research, 72(3), 213-224. Kalbfleisch, J.D. & Prentice, R.L. (1980). The...copyright protection in the United States. AFIT-ENV-MS-17-M-172 RELIABILITY AND COST IMPACTS FOR ATTRITABLE SYSTEMS THESIS Presented to... power of discrete time Markov chains, whether homogeneous or non-homogeneous, to model the reliability and dependability of repairable systems should

Overview of system reliability analyses for PSA

International Nuclear Information System (INIS)

Matsuoka, Takeshi

2012-01-01

Overall explanations are given for many matters relating to system reliability analysis. Systems engineering, Operations research, Industrial engineering, Quality control are briefly explained. Many system reliability analysis methods including advanced methods are introduced. Discussions are given for FMEA, reliability block diagram, Markov model, Petri net, Bayesian network, goal tree success tree, dynamic flow graph methodology, cell-to-cell mapping technique, the GO-FLOW and others. (author)

Fundamentals and applications of systems reliability analysis

International Nuclear Information System (INIS)

Boesebeck, K.; Heuser, F.W.; Kotthoff, K.

1976-01-01

The lecture gives a survey on the application of methods of reliability analysis to assess the safety of nuclear power plants. Possible statements of reliability analysis in connection with specifications of the atomic licensing procedure are especially dealt with. Existing specifications of safety criteria are additionally discussed with the help of reliability analysis by the example of the reliability analysis of a reactor protection system. Beyond the limited application to single safety systems, the significance of reliability analysis for a closed risk concept is explained in the last part of the lecture. (orig./LH) [de

Reliability evaluation of a natural circulation system

International Nuclear Information System (INIS)

Jafari, Jalil; D'Auria, Francesco; Kazeminejad, Hossein; Davilu, Hadi

2003-01-01

This paper discusses a reliability study performed with reference to a passive thermohydraulic natural circulation (NC) system, named TTL-1. A methodology based on probabilistic techniques has been applied with the main purpose to optimize the system design. The obtained results have been adopted to estimate the thermal-hydraulic reliability (TH-R) of the same system. A total of 29 relevant parameters (including nominal values and plausible ranges of variations) affecting the design and the NC performance of the TTL-1 loop are identified and a probability of occurrence is assigned for each value based on expert judgment. Following procedures established for the uncertainty evaluation of thermal-hydraulic system codes results, 137 system configurations have been selected and each configuration has been analyzed via the Relap5 best-estimate code. The reference system configuration and the failure criteria derived from the 'mission' of the passive system are adopted for the evaluation of the system TH-R. Four different definitions of a less-than-unity 'reliability-values' (where unity represents the maximum achievable reliability) are proposed for the performance of the selected passive system. This is normally considered fully reliable, i.e. reliability-value equal one, in typical Probabilistic Safety Assessment (PSA) applications in nuclear reactor safety. The two 'point' TH-R values for the considered NC system were found equal to 0.70 and 0.85, i.e. values comparable with the reliability of a pump installed in an 'equivalent' forced circulation (active) system having the same 'mission'. The design optimization study was completed by a regression analysis addressing the output of the 137 calculations: heat losses, undetected leakage, loop length, riser diameter, and equivalent diameter of the test section have been found as the most important parameters bringing to the optimal system design and affecting the TH-R. As added values for this work, the comparison has

Reliability analysis of self-actuated shutdown system

International Nuclear Information System (INIS)

Itooka, S.; Kumasaka, K.; Okabe, A.; Satoh, K.; Tsukui, Y.

1991-01-01

An analytical study was performed for the reliability of a self-actuated shutdown system (SASS) under the unprotected loss of flow (ULOF) event in a typical loop-type liquid metal fast breeder reactor (LMFBR) by the use of the response surface Monte Carlo analysis method. Dominant parameters for the SASS, such as Curie point characteristics, subassembly outlet coolant temperature, electromagnetic surface condition, etc., were selected and their probability density functions (PDFs) were determined by the design study information and experimental data. To get the response surface function (RSF) for the maximum coolant temperature, transient analyses of ULOF were performed by utilizing the experimental design method in the determination of analytical cases. Then, the RSF was derived by the multi-variable regression analysis. The unreliability of the SASS was evaluated as a probability that the maximum coolant temperature exceeded an acceptable level, employing the Monte Carlo calculation using the above PDFs and RSF. In this study, sensitivities to the dominant parameter were compared. The dispersion of subassembly outlet coolant temperature near the SASS-was found to be one of the most sensitive parameters. Fault tree analysis was performed using this value for the SASS in order to evaluate the shutdown system reliability. As a result of this study, the effectiveness of the SASS on the reliability improvement in the LMFBR shutdown system was analytically confirmed. This study has been performed as a part of joint research and development projects for DFBR under the sponsorship of the nine Japanese electric power companies, Electric Power Development Company and the Japan Atomic Power Company. (author)

Reliability Engineering

CERN Document Server

Lazzaroni, Massimo

2012-01-01

This book gives a practical guide for designers and users in Information and Communication Technology context. In particular, in the first Section, the definition of the fundamental terms according to the international standards are given. Then, some theoretical concepts and reliability models are presented in Chapters 2 and 3: the aim is to evaluate performance for components and systems and reliability growth. Chapter 4, by introducing the laboratory tests, puts in evidence the reliability concept from the experimental point of view. In ICT context, the failure rate for a given system can be

75 FR 35689 - System Personnel Training Reliability Standards

Science.gov (United States)

2010-06-23

... planning staff at control areas and reliability coordinators concerning power system characteristics and... Coordination--Staffing). \\11\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, Federal... American bulk electric system are competent to perform those reliability-related tasks.\\22\\ The proposed...

Grenada Education Management Information System

OpenAIRE

Porta, Emilio; Klein, Jennifer; Arcia, Gustavo; Nannyonjo, Harriet

2012-01-01

The Education Management Information System (EMIS) country report for Grenada includes the following headings: background which includes education data in Grenada, EMIS staff, facilities and equipment, EMIS data, and publications; prerequisites of quality; assurances of integrity; methodological soundness; accuracy and reliability; serviceability; and accessibility.

Influence of reliability of the relay protection to the whole reliability of electric power systems

International Nuclear Information System (INIS)

Stojanovski, Ljupcho I.

2001-01-01

The influence of the reliability of the elements of relay protection up today analyses of the reliability on electric power systems, very rare has been taken into consideration, in other words, in these analyses it is assumed that the reliability of the protection has value one. In this work an attempt is that through modelling of individual types of protection of the elements of high-voltage systems to make calculation to the influence of the reliability of the relay protection on the total reliability of the high-voltage systems.(Author)

75 FR 71625 - System Restoration Reliability Standards

Science.gov (United States)

2010-11-24

... to start operating and delivering electric power without assistance from the electric system... and system restoration and reporting following disturbances. \\3\\ North American Electric Reliability... Reliability Standards for the Bulk-Power System and determined that the proposed requirements are necessary to...

User's guide to the Reliability Estimation System Testbed (REST)

Science.gov (United States)

Nicol, David M.; Palumbo, Daniel L.; Rifkin, Adam

1992-01-01

The Reliability Estimation System Testbed is an X-window based reliability modeling tool that was created to explore the use of the Reliability Modeling Language (RML). RML was defined to support several reliability analysis techniques including modularization, graphical representation, Failure Mode Effects Simulation (FMES), and parallel processing. These techniques are most useful in modeling large systems. Using modularization, an analyst can create reliability models for individual system components. The modules can be tested separately and then combined to compute the total system reliability. Because a one-to-one relationship can be established between system components and the reliability modules, a graphical user interface may be used to describe the system model. RML was designed to permit message passing between modules. This feature enables reliability modeling based on a run time simulation of the system wide effects of a component's failure modes. The use of failure modes effects simulation enhances the analyst's ability to correctly express system behavior when using the modularization approach to reliability modeling. To alleviate the computation bottleneck often found in large reliability models, REST was designed to take advantage of parallel processing on hypercube processors.

Reliability data banks

International Nuclear Information System (INIS)

Cannon, A.G.; Bendell, A.

1991-01-01

Following an introductory chapter on Reliability, what is it, why it is needed, how it is achieved and measured, the principles of reliability data bases and analysis methodologies are the subject of the next two chapters. Achievements due to the development of data banks are mentioned for different industries in the next chapter, FACTS, a comprehensive information system for industrial safety and reliability data collection in process plants are covered next. CREDO, the Central Reliability Data Organization is described in the next chapter and is indexed separately, as is the chapter on DANTE, the fabrication reliability Data analysis system. Reliability data banks at Electricite de France and IAEA's experience in compiling a generic component reliability data base are also separately indexed. The European reliability data system, ERDS, and the development of a large data bank come next. The last three chapters look at 'Reliability data banks, - friend foe or a waste of time'? and future developments. (UK)

Reliability demonstration of imaging surveillance systems

International Nuclear Information System (INIS)

Sheridan, T.F.; Henderson, J.T.; MacDiarmid, P.R.

1979-01-01

Security surveillance systems which employ closed circuit television are being deployed with increasing frequency for the protection of property and other valuable assets. A need exists to demonstrate the reliability of such systems before their installation to assure that the deployed systems will operate when needed with only the scheduled amount of maintenance and support costs. An approach to the reliability demonstration of imaging surveillance systems which employ closed circuit television is described. Failure definitions based on industry television standards and imaging alarm assessment criteria for surveillance systems are discussed. Test methods which allow 24 hour a day operation without the need for numerous test scenarios, test personnel and elaborate test facilities are presented. Existing reliability demonstration standards are shown to apply which obviate the need for elaborate statistical tests. The demonstration methods employed are shown to have applications in other types of imaging surveillance systems besides closed circuit television

Assessing reliability in energy supply systems

International Nuclear Information System (INIS)

McCarthy, Ryan W.; Ogden, Joan M.; Sperling, Daniel

2007-01-01

Reliability has always been a concern in the energy sector, but concerns are escalating as energy demand increases and the political stability of many energy supply regions becomes more questionable. But how does one define and measure reliability? We introduce a method to assess reliability in energy supply systems in terms of adequacy and security. It derives from reliability assessment frameworks developed for the electricity sector, which are extended to include qualitative considerations and to be applicable to new energy systems by incorporating decision-making processes based on expert opinion and multi-attribute utility theory. The method presented here is flexible and can be applied to any energy system. To illustrate its use, we apply the method to two hydrogen pathways: (1) centralized steam reforming of imported liquefied natural gas with pipeline distribution of hydrogen, and (2) on-site electrolysis of water using renewable electricity produced independently from the electricity grid

Perceptual and Acoustic Reliability Estimates for the Speech Disorders Classification System (SDCS)

Science.gov (United States)

Shriberg, Lawrence D.; Fourakis, Marios; Hall, Sheryl D.; Karlsson, Heather B.; Lohmeier, Heather L.; McSweeny, Jane L.; Potter, Nancy L.; Scheer-Cohen, Alison R.; Strand, Edythe A.; Tilkens, Christie M.; Wilson, David L.

2010-01-01

A companion paper describes three extensions to a classification system for paediatric speech sound disorders termed the Speech Disorders Classification System (SDCS). The SDCS uses perceptual and acoustic data reduction methods to obtain information on a speaker's speech, prosody, and voice. The present paper provides reliability estimates for…

Field reliability of electronic systems

International Nuclear Information System (INIS)

Elm, T.

1984-02-01

This report investigates, through several examples from the field, the reliability of electronic units in a broader sense. That is, it treats not just random parts failure, but also inadequate reliability design and (externally and internally) induced failures. The report is not meant to be merely an indication of the state of the art for the reliability prediction methods we know, but also as a contribution to the investigation of man-machine interplay in the operation and repair of electronic equipment. The report firmly links electronics reliability to safety and risk analyses approaches with a broader, system oriented view of reliability prediction and with postfailure stress analysis. It is intended to reveal, in a qualitative manner, the existence of symptom and cause patterns. It provides a background for further investigations to identify the detailed mechanisms of the faults and the remedical actions and precautions for achieving cost effective reliability. (author)

System safety and reliability using object-oriented programming techniques

International Nuclear Information System (INIS)

Patterson-Hine, F.A.; Koen, B.V.

1987-01-01

Direct evaluation fault tree codes have been written in recursive, list-processing computer languages such as PL/1 (PATREC-I) and LISP (PATREC-L). The pattern-matching strategy implemented in these codes has been used extensively in France to evaluate system reliability. Recent reviews of the risk management process suggest that a data base containing plant-specific information be integrated with a package of codes used for probabilistic risk assessment (PRA) to alleviate some of the difficulties that make a PRA so costly and time-intensive. A new programming paradigm, object-oriented programming, is uniquely suited for the development of such a software system. A knowledge base and fault tree evaluation algorithm, based on previous experience with PATREC-L, have been implemented using object-oriented techniques, resulting in a reliability assessment environment that is easy to develop, modify, and extend

GStat 2.0: Grid Information System Status Monitoring

OpenAIRE

Field, L; Huang, J; Tsai, M

2009-01-01

Grid Information Systems are mission-critical components in today's production grid infrastructures. They enable users, applications and services to discover which services exist in the infrastructure and further information about the service structure and state. It is therefore important that the information system components themselves are functioning correctly and that the information content is reliable. Grid Status (GStat) is a tool that monitors the structural integrity of the EGEE info...

75 FR 72664 - System Personnel Training Reliability Standards

Science.gov (United States)

2010-11-26

...--Staffing). \\2\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, 72 FR 16416 (Apr... on the North American bulk electric system are competent to perform those reliability-related tasks... PER-004-2 will achieve a significant improvement in the reliability of the Bulk- Power System and...

Reliability-Based Inspection Planning for Structural Systems

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

1993-01-01

A general model for reliability-based optimal inspection and repair strategies for structural systems is described. The total expected costs in the design lifetime is minimized with the number of inspections, the inspection times and efforts as decision variables. The equivalence of this model...... with a preposterior analysis from statistical decision theory is discussed. It is described how information obtained by an inspection can be used in a repair decision. Stochastic models for inspection, measurement and repair actions are presented. The general model is applied for inspection and repair planning...

Reliable software systems via chains of object models with provably correct behavior

International Nuclear Information System (INIS)

Yakhnis, A.; Yakhnis, V.

1996-01-01

This work addresses specification and design of reliable safety-critical systems, such as nuclear reactor control systems. Reliability concerns are addressed in complimentary fashion by different fields. Reliability engineers build software reliability models, etc. Safety engineers focus on prevention of potential harmful effects of systems on environment. Software/hardware correctness engineers focus on production of reliable systems on the basis of mathematical proofs. The authors think that correctness may be a crucial guiding issue in the development of reliable safety-critical systems. However, purely formal approaches are not adequate for the task, because they neglect the connection with the informal customer requirements. They alleviate that as follows. First, on the basis of the requirements, they build a model of the system interactions with the environment, where the system is viewed as a black box. They will provide foundations for automated tools which will (a) demonstrate to the customer that all of the scenarios of system behavior are presented in the model, (b) uncover scenarios not present in the requirements, and (c) uncover inconsistent scenarios. The developers will work with the customer until the black box model will not possess scenarios (b) and (c) above. Second, the authors will build a chain of several increasingly detailed models, where the first model is the black box model and the last model serves to automatically generated proved executable code. The behavior of each model will be proved to conform to the behavior of the previous one. They build each model as a cluster of interactive concurrent objects, thus they allow both top-down and bottom-up development

System reliability effects in wind turbine blades

DEFF Research Database (Denmark)

Dimitrov, Nikolay Krasimirov; Friis-Hansen, Peter; Berggreen, Christian

2012-01-01

from reliability point of view. The present paper discusses the specifics of system reliability behavior of laminated composite sandwich panels, and solves an example system reliability problem for a glass fiber-reinforced composite sandwich structure subjected to in-plane compression.......Laminated composite sandwich panels have a layered structure, where individual layers have randomly varying stiffness and strength properties. The presence of multiple failure modes and load redistribution following partial failures are the reason for laminated composites to exhibit system behavior...

Probabilistic risk assessment course documentation. Volume 3. System reliability and analysis techniques, Session A - reliability

International Nuclear Information System (INIS)

Lofgren, E.V.

1985-08-01

This course in System Reliability and Analysis Techniques focuses on the quantitative estimation of reliability at the systems level. Various methods are reviewed, but the structure provided by the fault tree method is used as the basis for system reliability estimates. The principles of fault tree analysis are briefly reviewed. Contributors to system unreliability and unavailability are reviewed, models are given for quantitative evaluation, and the requirements for both generic and plant-specific data are discussed. Also covered are issues of quantifying component faults that relate to the systems context in which the components are embedded. All reliability terms are carefully defined. 44 figs., 22 tabs

Reliability analysis of containment isolation systems

International Nuclear Information System (INIS)

Pelto, P.J.; Ames, K.R.; Gallucci, R.H.

1985-06-01

This report summarizes the results of the Reliability Analysis of Containment Isolation System Project. Work was performed in five basic areas: design review, operating experience review, related research review, generic analysis and plant specific analysis. Licensee Event Reports (LERs) and Integrated Leak Rate Test (ILRT) reports provided the major sources of containment performance information used in this study. Data extracted from LERs were assembled into a computer data base. Qualitative and quantitative information developed for containment performance under normal operating conditions and design basis accidents indicate that there is room for improvement. A rough estimate of overall containment unavailability for relatively small leaks which violate plant technical specifications is 0.3. An estimate of containment unavailability due to large leakage events is in the range of 0.001 to 0.01. These estimates are dependent on several assumptions (particularly on event duration times) which are documented in the report

Reliability Growth in Space Life Support Systems

Science.gov (United States)

Jones, Harry W.

2014-01-01

A hardware system's failure rate often increases over time due to wear and aging, but not always. Some systems instead show reliability growth, a decreasing failure rate with time, due to effective failure analysis and remedial hardware upgrades. Reliability grows when failure causes are removed by improved design. A mathematical reliability growth model allows the reliability growth rate to be computed from the failure data. The space shuttle was extensively maintained, refurbished, and upgraded after each flight and it experienced significant reliability growth during its operational life. In contrast, the International Space Station (ISS) is much more difficult to maintain and upgrade and its failure rate has been constant over time. The ISS Carbon Dioxide Removal Assembly (CDRA) reliability has slightly decreased. Failures on ISS and with the ISS CDRA continue to be a challenge.

78 FR 44475 - Protection System Maintenance Reliability Standard

Science.gov (United States)

2013-07-24

... that the performance or product has some reliability-related value, then the requirement will have...] Protection System Maintenance Reliability Standard AGENCY: Federal Energy Regulatory Commission, Energy... Commission proposes to approve a revised Reliability Standard, PRC-005- 2--Protection System Maintenance, to...

Sequential decision reliability concept and failure rate assessment

International Nuclear Information System (INIS)

Ciftcioglu, O.

1990-11-01

Conventionally, a reliability concept is considered together with both each basic unit and their integration in a complicated large scale system such as a nuclear power plant (NPP). Basically, as the plant's operational status is determined by the information obtained from various sensors, the plant's reliability and the risk assessment is closely related to the reliability of the sensory information and hence the sensor components. However, considering the relevant information-processing systems, e.g. fault detection processors, there exists a further question about the reliability of such systems, specifically the reliability of the systems' decision-based outcomes by means of which the further actions are performed. To this end, a general sequential decision reliability concept and the failure rate assessment methodology is introduced. The implications of the methodology are investigated and the importance of the decision reliability concept in system operation is demonstrated by means of sensory signals in real-time from the Borssele NPP in the Netherlands. (author). 21 refs.; 8 figs

Reliability of power system with open access

International Nuclear Information System (INIS)

Ehsani, A.; Ranjbar, A. M.; Fotuhi Firuzabad, M.; Ehsani, M.

2003-01-01

Recently, in many countries, electric utility industry is undergoing considerable changes in regard to its structure and regulation. It can be clearly seen that the thrust towards privatization and deregulation or re regulation of the electric utility industry will introduce numerous reliability problems that will require new criteria and analytical tools that recognize the residual uncertainties in the new environment. In this paper, different risks and uncertainties in competitive electricity markets are briefly introduced; the approach of customers, operators, planners, generation bodies and network providers to the reliability of deregulated system is studied; the impact of dispersed generation on system reliability is evaluated; and finally, the reliability cost/reliability worth issues in the new competitive environment are considered

System reliability analysis with natural language and expert's subjectivity

International Nuclear Information System (INIS)

Onisawa, T.

1996-01-01

This paper introduces natural language expressions and expert's subjectivity to system reliability analysis. To this end, this paper defines a subjective measure of reliability and presents the method of the system reliability analysis using the measure. The subjective measure of reliability corresponds to natural language expressions of reliability estimation, which is represented by a fuzzy set defined on [0,1]. The presented method deals with the dependence among subsystems and employs parametrized operations of subjective measures of reliability which can reflect expert 's subjectivity towards the analyzed system. The analysis results are also expressed by linguistic terms. Finally this paper gives an example of the system reliability analysis by the presented method

76 FR 16277 - System Restoration Reliability Standards

Science.gov (United States)

2011-03-23

... electric system. Blackstart units are essential to restart generation and restore power to the grid in the... Standard EOP-007-0. \\2\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, 72 FR... = $5,894,624. Title: Mandatory Reliability Standards for the Bulk-Power System. Action: FERC 725A...

The development of an advanced information management system

International Nuclear Information System (INIS)

Kim, Seung Hwan

2005-01-01

Performing a PSA requires a lot of data to analyze, to evaluate the risk, to trace the process of results and to verify the results. KAERI is developing a PSA information database system, AIMS (Advanced Information Management System for PSA). The objective of AIMS development is to integrate and computerize all the distributed information of a PSA into a system and to enhance the accessibility to PSA information for all PSA related activities. We designed the PSA information database system for the following purposes: integrated PSA information management software, sensitivity analysis, quality assurance, anchor to another reliability database. The AIMS consists of a PSA Information database, Information browsing (searching) modules, and PSA automatic quantification manager modules

The development of an advanced information management system

Energy Technology Data Exchange (ETDEWEB)

Kim, Seung Hwan [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2005-07-01

Performing a PSA requires a lot of data to analyze, to evaluate the risk, to trace the process of results and to verify the results. KAERI is developing a PSA information database system, AIMS (Advanced Information Management System for PSA). The objective of AIMS development is to integrate and computerize all the distributed information of a PSA into a system and to enhance the accessibility to PSA information for all PSA related activities. We designed the PSA information database system for the following purposes: integrated PSA information management software, sensitivity analysis, quality assurance, anchor to another reliability database. The AIMS consists of a PSA Information database, Information browsing (searching) modules, and PSA automatic quantification manager modules.

IEEE guide for general principles of reliability analysis of nuclear power generating station protection systems

International Nuclear Information System (INIS)

Anon.

1975-01-01

Presented is the Institute of Electrical and Electronics Engineers, Inc. (IEEE) guide for general principles of reliability analysis of nuclear power generating station protection systems. The document has been prepared to provide the basic principles needed to conduct a reliability analysis of protection systems. Included is information on qualitative and quantitative analysis, guides for failure data acquisition and use, and guide for establishment of intervals

Reliability Electrical Power System of Hospital as Cold Standby System

Directory of Open Access Journals (Sweden)

Grabski Franciszek

2016-07-01

Full Text Available The probabilistic model of a hospital electrical power system consisting of mains, an emergency power system and the automatic transfer switch with the generator starter are discussed in this paper. The reliability model is semi-Markov process describing two different units renewable cold standby system and switch. The embedded Semi-Markov processes concept is applied for description of the system evolution. Time to failure of the system is represented by a random variable denoting the first passage time of the process from the given state to the subset of states. The appropriate theorems of the Semi-Markov processes theory allow us to evaluate the reliability function and some reliability characteristics.

Systems reliability analysis for the national ignition facility

International Nuclear Information System (INIS)

Majumdar, K.C.; Annese, C.E.; MacIntyre, A.T.; Sicherman, A.

1996-01-01

A Reliability, Availability and Maintainability (RAM) analysis was initiated for the National Ignition Facility (NIF). The NIF is an inertial confinement fusion research facility designed to achieve controlled thermonuclear reaction; the preferred site for the NIF is the Lawrence Livermore National Laboratory (LLNL). The NIF RAM analysis has three purposes: (1) to allocate top level reliability and availability goals for the systems, (2) to develop an operability model for optimum maintainability, and (3) to determine the achievability of the allocated goals of the RAM parameters for the NIF systems and the facility operation as a whole. An allocation model assigns the reliability and availability goals for front line and support systems by a top-down approach; reliability analysis uses a bottom-up approach to determine the system reliability and availability from component level to system level

Matrix-based system reliability method and applications to bridge networks

International Nuclear Information System (INIS)

Kang, W.-H.; Song Junho; Gardoni, Paolo

2008-01-01

Using a matrix-based system reliability (MSR) method, one can estimate the probabilities of complex system events by simple matrix calculations. Unlike existing system reliability methods whose complexity depends highly on that of the system event, the MSR method describes any general system event in a simple matrix form and therefore provides a more convenient way of handling the system event and estimating its probability. Even in the case where one has incomplete information on the component probabilities and/or the statistical dependence thereof, the matrix-based framework enables us to estimate the narrowest bounds on the system failure probability by linear programming. This paper presents the MSR method and applies it to a transportation network consisting of bridge structures. The seismic failure probabilities of bridges are estimated by use of the predictive fragility curves developed by a Bayesian methodology based on experimental data and existing deterministic models of the seismic capacity and demand. Using the MSR method, the probability of disconnection between each city/county and a critical facility is estimated. The probability mass function of the number of failed bridges is computed as well. In order to quantify the relative importance of bridges, the MSR method is used to compute the conditional probabilities of bridge failures given that there is at least one city disconnected from the critical facility. The bounds on the probability of disconnection are also obtained for cases with incomplete information

Reliability and safety engineering

CERN Document Server

Verma, Ajit Kumar; Karanki, Durga Rao

2016-01-01

Reliability and safety are core issues that must be addressed throughout the life cycle of engineering systems. Reliability and Safety Engineering presents an overview of the basic concepts, together with simple and practical illustrations. The authors present reliability terminology in various engineering fields, viz.,electronics engineering, software engineering, mechanical engineering, structural engineering and power systems engineering. The book describes the latest applications in the area of probabilistic safety assessment, such as technical specification optimization, risk monitoring and risk informed in-service inspection. Reliability and safety studies must, inevitably, deal with uncertainty, so the book includes uncertainty propagation methods: Monte Carlo simulation, fuzzy arithmetic, Dempster-Shafer theory and probability bounds. Reliability and Safety Engineering also highlights advances in system reliability and safety assessment including dynamic system modeling and uncertainty management. Cas...

Reliability of structural systems subject to fatigue

International Nuclear Information System (INIS)

Rackwitz, R.

1984-01-01

Concepts and computational procedures for the reliability calculation of structural systems subject to fatigue are outlined. Systems are dealt with by approximately computing componential times to first failure. So-called first-order reliability methods are then used to formulate dependencies between componential failures and to evaluate the system failure probability. (Author) [pt

Reliability and diagnostic of modular systems

Directory of Open Access Journals (Sweden)

J. Kohlas

2014-01-01

Full Text Available Reliability and diagnostic are in general two problems discussed separately. Yet the two problems are in fact closely related to each other. Here, this relation is considered in the simple case of modular systems. We show, how the computation of reliability and diagnostic can efficiently be done within the same Bayesian network induced by the modularity of the structure function of the system.

Reliability worth assessment of radial systems with distributed generation

OpenAIRE

Bellart Llavall, Francesc Xavier

2010-01-01

With recent advances in technology, utilities generation (DG) on the distribution systems. Reliability worth is very important in power system planning and operation. Having a DG ensures reli increase the reliability worth. This research project presents the study of a radial distribution system and the impact of placing DG in order to increase the reliability worth. where a DG have to be placed. The reliability improvement is measured by different reliability indices tha...

The reliability of nuclear power plant safety systems

International Nuclear Information System (INIS)

Susnik, J.

1978-01-01

A criterion was established concerning the protection that nuclear power plant (NPP) safety systems should afford. An estimate of the necessary or adequate reliability of the total complex of safety systems was derived. The acceptable unreliability of auxiliary safety systems is given, provided the reliability built into the specific NPP safety systems (ECCS, Containment) is to be fully utilized. A criterion for the acceptable unreliability of safety (sub)systems which occur in minimum cut sets having three or more components of the analysed fault tree was proposed. A set of input MTBF or MTTF values which fulfil all the set criteria and attain the appropriate overall reliability was derived. The sensitivity of results to input reliability data values was estimated. Numerical reliability evaluations were evaluated by the programs POTI, KOMBI and particularly URSULA, the last being based on Vesely's kinetic fault tree theory. (author)

Physical attraction to reliable, low variability nervous systems: Reaction time variability predicts attractiveness.

Science.gov (United States)

Butler, Emily E; Saville, Christopher W N; Ward, Robert; Ramsey, Richard

2017-01-01

The human face cues a range of important fitness information, which guides mate selection towards desirable others. Given humans' high investment in the central nervous system (CNS), cues to CNS function should be especially important in social selection. We tested if facial attractiveness preferences are sensitive to the reliability of human nervous system function. Several decades of research suggest an operational measure for CNS reliability is reaction time variability, which is measured by standard deviation of reaction times across trials. Across two experiments, we show that low reaction time variability is associated with facial attractiveness. Moreover, variability in performance made a unique contribution to attractiveness judgements above and beyond both physical health and sex-typicality judgements, which have previously been associated with perceptions of attractiveness. In a third experiment, we empirically estimated the distribution of attractiveness preferences expected by chance and show that the size and direction of our results in Experiments 1 and 2 are statistically unlikely without reference to reaction time variability. We conclude that an operating characteristic of the human nervous system, reliability of information processing, is signalled to others through facial appearance. Copyright © 2016 Elsevier B.V. All rights reserved.

Time domain series system definition and gear set reliability modeling

International Nuclear Information System (INIS)

Xie, Liyang; Wu, Ningxiang; Qian, Wenxue

2016-01-01

Time-dependent multi-configuration is a typical feature for mechanical systems such as gear trains and chain drives. As a series system, a gear train is distinct from a traditional series system, such as a chain, in load transmission path, system-component relationship, system functioning manner, as well as time-dependent system configuration. Firstly, the present paper defines time-domain series system to which the traditional series system reliability model is not adequate. Then, system specific reliability modeling technique is proposed for gear sets, including component (tooth) and subsystem (tooth-pair) load history description, material priori/posterior strength expression, time-dependent and system specific load-strength interference analysis, as well as statistically dependent failure events treatment. Consequently, several system reliability models are developed for gear sets with different tooth numbers in the scenario of tooth root material ultimate tensile strength failure. The application of the models is discussed in the last part, and the differences between the system specific reliability model and the traditional series system reliability model are illustrated by virtue of several numerical examples. - Highlights: • A new type of series system, i.e. time-domain multi-configuration series system is defined, that is of great significance to reliability modeling. • Multi-level statistical analysis based reliability modeling method is presented for gear transmission system. • Several system specific reliability models are established for gear set reliability estimation. • The differences between the traditional series system reliability model and the new model are illustrated.

Influence Of Inspection Intervals On Mechanical System Reliability

International Nuclear Information System (INIS)

Zilberman, B.

1998-01-01

In this paper a methodology of reliability analysis of mechanical systems with latent failures is described. Reliability analysis of such systems must include appropriate usage of check intervals for latent failure detection. The methodology suggests, that based on system logic the analyst decides at the beginning if a system can fail actively or latently and propagates this approach through all system levels. All inspections are assumed to be perfect (all failures are detected and repaired and no new failures are introduced as a result of the maintenance). Additional assumptions are that mission time is much smaller, than check intervals and all components have constant failure rates. Analytical expressions for reliability calculates are provided, based on fault tree and Markov modeling techniques (for two and three redundant systems with inspection intervals). The proposed methodology yields more accurate results than are obtained by not using check intervals or using half check interval times. The conventional analysis assuming that at the beginning of each mission system is as new, give an optimistic prediction of system reliability. Some examples of reliability calculations of mechanical systems with latent failures and establishing optimum check intervals are provided

Reliability planning in distributed electric energy systems

Energy Technology Data Exchange (ETDEWEB)

Kahn, E.

1978-10-01

The goal of this paper is to develop tools for technology evaluation that address questions involving the economics of large-scale systems. The kind of cost discussed usually involves some dynamic aspect of the energy system. In particular, such properties as flexibility, stability, and resilience are features of entire systems. Special attention must be paid to the question of reliability, i.e., availability on demand. The storage problem and the planning for reliability in utility systems are the subjects of this paper. The introductory chapter addresses preliminary definitions--reliability planning, uncertainty, resilience, and other sensitivities. The study focuses on the contrast between conventional power generation technologies with controllable output and intermittent resources such as wind and solar electric conversion devices. The system studied is a stylized representation of California conditions. Significant differences were found in reliability planning requirements (and therefore costs) for systems dominated by central station plants as opposed to those dominated by intermittent resource technologies. It is argued that existing hydroelectric facilities need re-optimization. These plants provide the only currently existing bulk power storage in electric energy systems. 38 references. (MCW)

COMPOSITE METHOD OF RELIABILITY RESEARCH FOR HIERARCHICAL MULTILAYER ROUTING SYSTEMS

Directory of Open Access Journals (Sweden)

R. B. Tregubov

2016-09-01

Full Text Available The paper deals with the idea of a research method for hierarchical multilayer routing systems. The method represents a composition of methods of graph theories, reliability, probabilities, etc. These methods are applied to the solution of different private analysis and optimization tasks and are systemically connected and coordinated with each other through uniform set-theoretic representation of the object of research. The hierarchical multilayer routing systems are considered as infrastructure facilities (gas and oil pipelines, automobile and railway networks, systems of power supply and communication with distribution of material resources, energy or information with the use of hierarchically nested functions of routing. For descriptive reasons theoretical constructions are considered on the example of task solution of probability determination for up state of specific infocommunication system. The author showed the possibility of constructive combination of graph representation of structure of the object of research and a logic probable analysis method of its reliability indices through uniform set-theoretic representation of its elements and processes proceeding in them.

A Reliable Measure of Information Security Awareness and the Identification of Bias in Responses

Directory of Open Access Journals (Sweden)

Agata McCormac

2017-11-01

Full Text Available The Human Aspects of Information Security Questionnaire (HAIS-Q is designed to measure Information Security Awareness. More specifically, the tool measures an individual’s knowledge, attitude, and self-reported behaviour relating to information security in the workplace. This paper reports on the reliability of the HAIS-Q, including test-retest reliability and internal consistency. The paper also assesses the reliability of three preliminary over-claiming items, designed specifically to complement the HAIS-Q, and identify those individuals who provide socially desirable responses. A total of 197 working Australians completed two iterations of the HAIS-Q and the over-claiming items, approximately 4 weeks apart. Results of the analysis showed that the HAIS-Q was externally reliable and internally consistent. Therefore, the HAIS-Q can be used to reliably measure information security awareness. Reliability testing on the preliminary over-claiming items was not as robust and further development is required and recommended. The implications of these findings mean that organisations can confidently use the HAIS-Q to not only measure the current state of employee information security awareness within their organisation, but they can also measure the effectiveness and impacts of training interventions, information security awareness programs and campaigns. The influence of cultural changes and the effect of security incidents can also be assessed.

Reliability analysis of reactor protection systems

International Nuclear Information System (INIS)

Alsan, S.

1976-07-01

A theoretical mathematical study of reliability is presented and the concepts subsequently defined applied to the study of nuclear reactor safety systems. The theory is applied to investigations of the operational reliability of the Siloe reactor from the point of view of rod drop. A statistical study conducted between 1964 and 1971 demonstrated that most rod drop incidents arose from circumstances associated with experimental equipment (new set-ups). The reliability of the most suitable safety system for some recently developed experimental equipment is discussed. Calculations indicate that if all experimental equipment were equipped with these new systems, only 1.75 rod drop accidents would be expected to occur per year on average. It is suggested that all experimental equipment should be equipped with these new safety systems and tested every 21 days. The reliability of the new safety system currently being studied for the Siloe reactor was also investigated. The following results were obtained: definite failures must be detected immediately as a result of the disturbances produced; the repair time must not exceed a few hours; the equipment must be tested every week. Under such conditions, the rate of accidental rod drops is about 0.013 on average per year. The level of nondefinite failures is less than 10 -6 per hour and the level of nonprotection 1 hour per year. (author)

Distribution System Reliability Analysis for Smart Grid Applications

Science.gov (United States)

Aljohani, Tawfiq Masad

Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capable of being a self-healing grid, offering the ability to overcome the interruption problems that face the utility and cost it tens of millions in repair and loss. To address its reliability concerns, the power utilities and interested parties have spent extensive amount of time and effort to analyze and study the reliability of the generation and transmission sectors of the power grid. Only recently has attention shifted to be focused on improving the reliability of the distribution network, the connection joint between the power providers and the consumers where most of the electricity problems occur. In this work, we will examine the effect of the smart grid applications in improving the reliability of the power distribution networks. The test system used in conducting this thesis is the IEEE 34 node test feeder, released in 2003 by the Distribution System Analysis Subcommittee of the IEEE Power Engineering Society. The objective is to analyze the feeder for the optimal placement of the automatic switching devices and quantify their proper installation based on the performance of the distribution system. The measures will be the changes in the reliability system indices including SAIDI, SAIFI, and EUE. The goal is to design and simulate the effect of the installation of the Distributed Generators (DGs) on the utility's distribution system and measure the potential improvement of its reliability. The software used in this work is DISREL, which is intelligent power distribution software that is developed by General Reliability Co.

CADRIGS--computer aided design reliability interactive graphics system

International Nuclear Information System (INIS)

Kwik, R.J.; Polizzi, L.M.; Sticco, S.; Gerrard, P.B.; Yeater, M.L.; Hockenbury, R.W.; Phillips, M.A.

1982-01-01

An integrated reliability analysis program combining graphic representation of fault trees, automated data base loadings and reference, and automated construction of reliability code input files was developed. The functional specifications for CADRIGS, the computer aided design reliability interactive graphics system, are presented. Previously developed fault tree segments used in auxiliary feedwater system safety analysis were constructed on CADRIGS and, when combined, yielded results identical to those resulting from manual input to the same reliability codes

Preliminary investigation on reliability assessment of passive safety system

International Nuclear Information System (INIS)

Huang Changfan; Kuang Bo

2012-01-01

The reliability evaluation of passive safety system plays an important part in probabilistic safety assessment (PSA) of nuclear power plant applying passive safety design, which depends quantitatively on reliabilities of passive safety system. According to the object of reliability assessment of passive safety system, relevant parameters are identified. Then passive system behavior during accident scenarios are studied. A practical example of this method is given for the case of reliability assessment of AP1000 passive heat removal system in loss of normal feedwater accident. Key and design parameters of PRHRS are identified and functional failure criteria are established. Parameter combinations acquired by Latin hyper~ cube sampling (LHS) in possible parametric ranges are input and calculations of uncertainty propagation through RELAP5/MOD3 code are carried out. Based on the calculations, sensitivity assessment on PRHRS functional criteria and reliability evaluation of the system are presented, which might provide further PSA with PRHR system reliability. (authors)

Systems reliability in high risk situations

International Nuclear Information System (INIS)

Hunns, D.M.

1974-12-01

A summary is given of five papers and the discussion of a seminar promoted by the newly-formed National Centre of Systems Reliability. The topics covered include hazard analysis, reliability assessment, and risk assessment in both nuclear and non-nuclear industries. (U.K.)

A Closed-Form Technique for the Reliability and Risk Assessment of Wind Turbine Systems

Directory of Open Access Journals (Sweden)

Leonardo Dueñas-Osorio

2012-06-01

Full Text Available This paper proposes a closed-form method to evaluate wind turbine system reliability and associated failure consequences. Monte Carlo simulation, a widely used approach for system reliability assessment, usually requires large numbers of computational experiments, while existing analytical methods are limited to simple system event configurations with a focus on average values of reliability metrics. By analyzing a wind turbine system and its components in a combinatorial yet computationally efficient form, the proposed approach provides an entire probability distribution of system failure that contains all possible configurations of component failure and survival events. The approach is also capable of handling unique component attributes such as downtime and repair cost needed for risk estimations, and enables sensitivity analysis for quantifying the criticality of individual components to wind turbine system reliability. Applications of the technique are illustrated by assessing the reliability of a 12-subassembly turbine system. In addition, component downtimes and repair costs of components are embedded in the formulation to compute expected annual wind turbine unavailability and repair cost probabilities, and component importance metrics useful for maintenance planning and research prioritization. Furthermore, this paper introduces a recursive solution to closed-form method and applies this to a 45-component turbine system. The proposed approach proves to be computationally efficient and yields vital reliability information that could be readily used by wind farm stakeholders for decision making and risk management.

System Reliability of Timber Structures with Ductile Behaviour

DEFF Research Database (Denmark)

Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Čizmar, Dean

2011-01-01

The present paper considers the evaluation of timber structures with the focus on robustness due to connection ductility. The robustness analysis is based on the structural reliability framework applied to a simplified mechanical system. The structural timber system is depicted as a parallel system....... An evaluation method of the ductile behaviour is introduced. For different ductile behaviours, the system reliability is estimated based on Monte Carlo simulation. A correlation between the strength of the structural elements is introduced. The results indicate that the reliability of a structural timber system...

Reliability engineering for nuclear and other high technology systems

International Nuclear Information System (INIS)

Lakner, A.A.; Anderson, R.T.

1985-01-01

This book is written for the reliability instructor, program manager, system engineer, design engineer, reliability engineer, nuclear regulator, probability risk assessment (PRA) analyst, general manager and others who are involved in system hardware acquisition, design and operation and are concerned with plant safety and operational cost-effectiveness. It provides criteria, guidelines and comprehensive engineering data affecting reliability; it covers the key aspects of system reliability as it relates to conceptual planning, cost tradeoff decisions, specification, contractor selection, design, test and plant acceptance and operation. It treats reliability as an integrated methodology, explicitly describing life cycle management techniques as well as the basic elements of a total hardware development program, including: reliability parameters and design improvement attributes, reliability testing, reliability engineering and control. It describes how these elements can be defined during procurement, and implemented during design and development to yield reliable equipment. (author)

Reliability demonstration test planning: A three dimensional consideration

International Nuclear Information System (INIS)

Yadav, Om Prakash; Singh, Nanua; Goel, Parveen S.

2006-01-01

Increasing customer demand for reliability, fierce market competition on time-to-market and cost, and highly reliable products are making reliability testing more challenging task. This paper presents a systematic approach for identifying critical elements (subsystems and components) of the system and deciding the types of test to be performed to demonstrate reliability. It decomposes the system into three dimensions (i.e. physical, functional and time) and identifies critical elements in the design by allocating system level reliability to each candidate. The decomposition of system level reliability is achieved by using criticality index. The numerical value of criticality index for each candidate is derived based on the information available from failure mode and effects analysis (FMEA) document or warranty data from a prior system. It makes use of this information to develop reliability demonstration test plan for the identified (critical) failure mechanisms and physical elements. It also highlights the benefits of using prior information in order to locate critical spots in the design and in subsequent development of test plans. A case example is presented to demonstrate the proposed approach

Foundations for a time reliability correlation system to quantify human reliability

International Nuclear Information System (INIS)

Dougherty, E.M. Jr.; Fragola, J.R.

1988-01-01

Time reliability correlations (TRCs) have been used in human reliability analysis (HRA) in conjunction with probabilistic risk assessment (PRA) to quantify post-initiator human failure events. The first TRCs were judgmental but recent data taken from simulators have provided evidence for development of a system of TRCs. This system has the equational form: t = tau R X tau U , where the first factor is the lognormally distributed random variable of successful response time, derived from the simulator data, and the second factor is a unitary lognormal random variable to account for uncertainty in the model. The first random variable is further factored into a median response time and a factor to account for the dominant type of behavior assumed to be involved in the response and a second factor to account for other influences on the reliability of the response

Developing Scalable Information Security Systems

Directory of Open Access Journals (Sweden)

Valery Konstantinovich Ablekov

2013-06-01

Full Text Available Existing physical security systems has wide range of lacks, including: high cost, a large number of vulnerabilities, problems of modification and support system. This paper covers an actual problem of developing systems without this list of drawbacks. The paper presents the architecture of the information security system, which operates through the network protocol TCP/IP, including the ability to connect different types of devices and integration with existing security systems. The main advantage is a significant increase in system reliability, scalability, both vertically and horizontally, with minimal cost of both financial and time resources.

Load Control System Reliability

Energy Technology Data Exchange (ETDEWEB)

Trudnowski, Daniel [Montana Tech of the Univ. of Montana, Butte, MT (United States)

2015-04-03

This report summarizes the results of the Load Control System Reliability project (DOE Award DE-FC26-06NT42750). The original grant was awarded to Montana Tech April 2006. Follow-on DOE awards and expansions to the project scope occurred August 2007, January 2009, April 2011, and April 2013. In addition to the DOE monies, the project also consisted of matching funds from the states of Montana and Wyoming. Project participants included Montana Tech; the University of Wyoming; Montana State University; NorthWestern Energy, Inc., and MSE. Research focused on two areas: real-time power-system load control methodologies; and, power-system measurement-based stability-assessment operation and control tools. The majority of effort was focused on area 2. Results from the research includes: development of fundamental power-system dynamic concepts, control schemes, and signal-processing algorithms; many papers (including two prize papers) in leading journals and conferences and leadership of IEEE activities; one patent; participation in major actual-system testing in the western North American power system; prototype power-system operation and control software installed and tested at three major North American control centers; and, the incubation of a new commercial-grade operation and control software tool. Work under this grant certainly supported the DOE-OE goals in the area of “Real Time Grid Reliability Management.”

Workshop Proceedings: Utilizing global information systems

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

This one day workshop was attended by 50 delegates representing 20 countries. Fourteen papers dealing with cleaner production/cleaner technology global information systems were presented. The objective of the workshop was to increase cooperation and interaction on international clean production/clean technology information transfer activities and to identify ways to ensure continued cooperation and system improvements. Topics discussed included information format to meet user needs; coordination of effort to avoid duplication and to encourage consistency in information delivery; and marketing, to expand the dissemination of information on cleaner production/cleaner technology. In terms of information format, content, systems and reliability were identified as target issues. The group discussing coordination of effort suggested that a wholesale/retail approach to information dissemination be adopted. The group also called for regular meetings to supplement communication via the Internet. The marketing group suggested that there is a need to show the benefits of technologies and to establish links to industrial associations as being critical to success.

Time-Varying, Multi-Scale Adaptive System Reliability Analysis of Lifeline Infrastructure Networks

Energy Technology Data Exchange (ETDEWEB)

Gearhart, Jared Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kurtz, Nolan Scot [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2014-09-01

The majority of current societal and economic needs world-wide are met by the existing networked, civil infrastructure. Because the cost of managing such infrastructure is high and increases with time, risk-informed decision making is essential for those with management responsibilities for these systems. To address such concerns, a methodology that accounts for new information, deterioration, component models, component importance, group importance, network reliability, hierarchical structure organization, and efficiency concerns has been developed. This methodology analyzes the use of new information through the lens of adaptive Importance Sampling for structural reliability problems. Deterioration, multi-scale bridge models, and time-variant component importance are investigated for a specific network. Furthermore, both bridge and pipeline networks are studied for group and component importance, as well as for hierarchical structures in the context of specific networks. Efficiency is the primary driver throughout this study. With this risk-informed approach, those responsible for management can address deteriorating infrastructure networks in an organized manner.

Highly reliable electro-hydraulic control system

International Nuclear Information System (INIS)

Mande, Morima; Hiyama, Hiroshi; Takahashi, Makoto

1984-01-01

The unscheduled shutdown of nuclear power stations disturbs power system, and exerts large influence on power generation cost due to the lowering of capacity ratio; therefore, high reliability is required for the control system of nuclear power stations. Toshiba Corp. has exerted effort to improve the reliability of the control system of power stations, and in this report, the electro-hydraulic control system for the turbines of nuclear power stations is described. The main functions of the electro-hydraulic control system are the control of main steam pressure with steam regulation valves and turbine bypass valves, the control of turbine speed and load, the prevention of turbine overspeed, the protection of turbines and so on. The system is composed of pressure sensors and a speed sensor, the control board containing the electronic circuits for control computation and protective sequence, the oil cylinders, servo valves and opening detectors of the valves for control, a high pressure oil hydraulic machine and piping, the operating panel and so on. The main features are the adoption of tripling intermediate value selection method, the multiplying of protection sensors and the adoption of 2 out of 3 trip logic, the multiplying of power sources, the improvement of the reliability of electronic circuit hardware and oil hydraulic system. (Kako, I.)

Reliability assessment of restructured power systems using reliability network equivalent and pseudo-sequential simulation techniques

International Nuclear Information System (INIS)

Ding, Yi; Wang, Peng; Goel, Lalit; Billinton, Roy; Karki, Rajesh

2007-01-01

This paper presents a technique to evaluate reliability of a restructured power system with a bilateral market. The proposed technique is based on the combination of the reliability network equivalent and pseudo-sequential simulation approaches. The reliability network equivalent techniques have been implemented in the Monte Carlo simulation procedure to reduce the computational burden of the analysis. Pseudo-sequential simulation has been used to increase the computational efficiency of the non-sequential simulation method and to model the chronological aspects of market trading and system operation. Multi-state Markov models for generation and transmission systems are proposed and implemented in the simulation. A new load shedding scheme is proposed during generation inadequacy and network congestion to minimize the load curtailment. The IEEE reliability test system (RTS) is used to illustrate the technique. (author)

FUNDAMENTALS OF RELIABILITY OF ELECTRIC POWER SYSTEM AND EQUIPMENT

OpenAIRE

Engr. Anumaka; Michael Chukwukadibia

2011-01-01

Today, the electric power system consists of complex interconnected network which are prone to different problems that militates against the reliability of the power system. Inadequate reliability in the power system causes problems such as high failure rate of power system installations and consumer equipment, transient and intransient faults, symmetrical faults etc. This paper provides an extensive review of the powers system and equipment reliability and related failure patterns in equipment.

Reliability analysis of Angra I safety systems

International Nuclear Information System (INIS)

Oliveira, L.F.S. de; Soto, J.B.; Maciel, C.C.; Gibelli, S.M.O.; Fleming, P.V.; Arrieta, L.A.

1980-07-01

An extensive reliability analysis of some safety systems of Angra I, are presented. The fault tree technique, which has been successfully used in most reliability studies of nuclear safety systems performed to date is employed. Results of a quantitative determination of the unvailability of the accumulator and the containment spray injection systems are presented. These results are also compared to those reported in WASH-1400. (E.G.) [pt

The new features of the ExaMe evaluation system and reliability of its fixed tests.

Science.gov (United States)

Martinková, P; Zvára, K; Zvárová, J; Zvára, K

2006-01-01

The ExaMe system for the evaluation of targeted knowledge has been in development since 1998. The new features of the ExaMe system are introduced in this paper. Especially, the new three-layer architecture is described. Besides the system itself, the properties of fixed tests in the ExaMe system are studied. In special detail, the reliability of the fixed tests is discussed. The theory background is explained and some limitations of the reliability are pointed out. Three characteristics used for estimation of reliability of educational tests are discussed: Cronbach's alpha, standardized item alpha and split half coefficient. The relation between these characteristics and reliability and between characteristics themselves is investigated. In more detail, the properties of Cronbach's alpha, the characteristics mostly used for the estimation of reliability, are discussed. A confidence interval is introduced for the characteristics. Since 2000, the serviceability of the ExaMe evaluation system as the supporting evaluation tool has been repeatedly shown at the courses of Ph.D. studies in biomedical informatics at Charles University in Prague. The ExaMe system also opens new possibilities for self-evaluation and distance learning, especially when connected with electronic books on the Internet. The estimation of reliability of tests contains some limitations. Keeping them in mind, we can still get some information about the quality of certain educational tests. Therefore, the estimation of reliability of the fixed tests is implemented in the ExaMe system.

Reliability estimation system: its application to the nuclear geophysical sampling of ore deposits

International Nuclear Information System (INIS)

Khaykovich, I.M.; Savosin, S.I.

1992-01-01

The reliability estimation system accepted in the Soviet Union for sampling data in nuclear geophysics is based on unique requirements in metrology and methodology. It involves estimating characteristic errors in calibration, as well as errors in measurement and interpretation. This paper describes the methods of estimating the levels of systematic and random errors at each stage of the problem. The data of nuclear geophysics sampling are considered to be reliable if there are no statistically significant, systematic differences between ore intervals determined by this method and by geological control, or by other methods of sampling; the reliability of the latter having been verified. The difference between the random errors is statistically insignificant. The system allows one to obtain information on the parameters of ore intervals with a guaranteed random error and without systematic errors. (Author)

Software engineering practices for control system reliability

International Nuclear Information System (INIS)

S. K. Schaffner; K. S White

1999-01-01

This paper will discuss software engineering practices used to improve Control System reliability. The authors begin with a brief discussion of the Software Engineering Institute's Capability Maturity Model (CMM) which is a framework for evaluating and improving key practices used to enhance software development and maintenance capabilities. The software engineering processes developed and used by the Controls Group at the Thomas Jefferson National Accelerator Facility (Jefferson Lab), using the Experimental Physics and Industrial Control System (EPICS) for accelerator control, are described. Examples are given of how their procedures have been used to minimized control system downtime and improve reliability. While their examples are primarily drawn from their experience with EPICS, these practices are equally applicable to any control system. Specific issues addressed include resource allocation, developing reliable software lifecycle processes and risk management

Construction of pilot system for the Korea information system of occupational exposure

International Nuclear Information System (INIS)

Na, Seong Ho; Park, Moon Il; Im, Bok Soo; Lee, Seon Mi; Kim, Hyung Uk; Chae, Eun Yeong

2003-01-01

In this study, the construction of Korea Information System of Occupational Exposure (KISOE) system is designed with occupational exposure control system based on information evaluation technology and it makes the reliability of the personal exposure by use of personal dose verification. While the operation of national based radiation worker protection system, this system are settled the control system for radiation worker and ALARA. The purpose of construction and operation of pilot system of KISOE systematically is to derive the master plan of KISOE, stable development of this system, and serve the high quality radiation use internationally

Construction of pilot system for the Korea information system of occupational exposure

Energy Technology Data Exchange (ETDEWEB)

Na, Seong Ho [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of); Park, Moon Il; Im, Bok Soo; Lee, Seon Mi; Kim, Hyung Uk; Chae, Eun Yeong [ADDLAB Co., Ltd., Taejon (Korea, Republic of)

2003-01-15

In this study, the construction of Korea Information System of Occupational Exposure (KISOE) system is designed with occupational exposure control system based on information evaluation technology and it makes the reliability of the personal exposure by use of personal dose verification. While the operation of national based radiation worker protection system, this system are settled the control system for radiation worker and ALARA. The purpose of construction and operation of pilot system of KISOE systematically is to derive the master plan of KISOE, stable development of this system, and serve the high quality radiation use internationally.

Telecommunications system reliability engineering theory and practice

CERN Document Server

Ayers, Mark L

2012-01-01

"Increasing system complexity require new, more sophisticated tools for system modeling and metric calculation. Bringing the field up to date, this book provides telecommunications engineers with practical tools for analyzing, calculating, and reporting availability, reliability, and maintainability metrics. It gives the background in system reliability theory and covers in-depth applications in fiber optic networks, microwave networks, satellite networks, power systems, and facilities management. Computer programming tools for simulating the approaches presented, using the Matlab software suite, are also provided"

Development of Student Information Management System based on Cloud Computing Platform

Directory of Open Access Journals (Sweden)

Ibrahim A. ALAMERI

2017-10-01

Full Text Available The management and provision of information about the educational process is an essential part of effective management of the educational process in the institutes of higher education. In this paper the requirements of a reliable student management system are analyzed, formed a use-case model of student information management system, designed and implemented the architecture of the application. Regarding the implementation process, modern approaches were used to develop and deploy a reliable online application in cloud computing environments specifically.

Heroic Reliability Improvement in Manned Space Systems

Science.gov (United States)

Jones, Harry W.

2017-01-01

System reliability can be significantly improved by a strong continued effort to identify and remove all the causes of actual failures. Newly designed systems often have unexpected high failure rates which can be reduced by successive design improvements until the final operational system has an acceptable failure rate. There are many causes of failures and many ways to remove them. New systems may have poor specifications, design errors, or mistaken operations concepts. Correcting unexpected problems as they occur can produce large early gains in reliability. Improved technology in materials, components, and design approaches can increase reliability. The reliability growth is achieved by repeatedly operating the system until it fails, identifying the failure cause, and fixing the problem. The failure rate reduction that can be obtained depends on the number and the failure rates of the correctable failures. Under the strong assumption that the failure causes can be removed, the decline in overall failure rate can be predicted. If a failure occurs at the rate of lambda per unit time, the expected time before the failure occurs and can be corrected is 1/lambda, the Mean Time Before Failure (MTBF). Finding and fixing a less frequent failure with the rate of lambda/2 per unit time requires twice as long, time of 1/(2 lambda). Cutting the failure rate in half requires doubling the test and redesign time and finding and eliminating the failure causes.Reducing the failure rate significantly requires a heroic reliability improvement effort.

Reliability training

Science.gov (United States)

Lalli, Vincent R. (Editor); Malec, Henry A. (Editor); Dillard, Richard B.; Wong, Kam L.; Barber, Frank J.; Barina, Frank J.

1992-01-01

Discussed here is failure physics, the study of how products, hardware, software, and systems fail and what can be done about it. The intent is to impart useful information, to extend the limits of production capability, and to assist in achieving low cost reliable products. A review of reliability for the years 1940 to 2000 is given. Next, a review of mathematics is given as well as a description of what elements contribute to product failures. Basic reliability theory and the disciplines that allow us to control and eliminate failures are elucidated.

Long-term Mechanical Circulatory Support System reliability recommendation by the National Clinical Trial Initiative subcommittee.

Science.gov (United States)

Lee, James

2009-01-01

The Long-Term Mechanical Circulatory Support (MCS) System Reliability Recommendation was published in the American Society for Artificial Internal Organs (ASAIO) Journal and the Annals of Thoracic Surgery in 1998. At that time, it was stated that the document would be periodically reviewed to assess its timeliness and appropriateness within 5 years. Given the wealth of clinical experience in MCS systems, a new recommendation has been drafted by consensus of a group of representatives from the medical community, academia, industry, and government. The new recommendation describes a reliability test methodology and provides detailed reliability recommendations. In addition, the new recommendation provides additional information and clinical data in appendices that are intended to assist the reliability test engineer in the development of a reliability test that is expected to give improved predictions of clinical reliability compared with past test methods. The appendices are available for download at the ASAIO journal web site at www.asaiojournal.com.

Personnel reliability impact on petrochemical facilities monitoring system's failure skipping probability

Science.gov (United States)

Kostyukov, V. N.; Naumenko, A. P.

2017-08-01

The paper dwells upon urgent issues of evaluating impact of actions conducted by complex technological systems operators on their safe operation considering application of condition monitoring systems for elements and sub-systems of petrochemical production facilities. The main task for the research is to distinguish factors and criteria of monitoring system properties description, which would allow to evaluate impact of errors made by personnel on operation of real-time condition monitoring and diagnostic systems for machinery of petrochemical facilities, and find and objective criteria for monitoring system class, considering a human factor. On the basis of real-time condition monitoring concepts of sudden failure skipping risk, static and dynamic error, monitoring systems, one may solve a task of evaluation of impact that personnel's qualification has on monitoring system operation in terms of error in personnel or operators' actions while receiving information from monitoring systems and operating a technological system. Operator is considered as a part of the technological system. Although, personnel's behavior is usually a combination of the following parameters: input signal - information perceiving, reaction - decision making, response - decision implementing. Based on several researches on behavior of nuclear powers station operators in USA, Italy and other countries, as well as on researches conducted by Russian scientists, required data on operator's reliability were selected for analysis of operator's behavior at technological facilities diagnostics and monitoring systems. The calculations revealed that for the monitoring system selected as an example, the failure skipping risk for the set values of static (less than 0.01) and dynamic (less than 0.001) errors considering all related factors of data on reliability of information perception, decision-making, and reaction fulfilled is 0.037, in case when all the facilities and error probability are under

Addressing the reliability issues of intelligent well systems

International Nuclear Information System (INIS)

Drakeley, Brian; Douglas, Neil

2000-01-01

New Technology receives its fair share of 'risk aversion' both in good and not so good economic times from oil and gas operators evaluating application opportunities. This paper presents details of a strategy developed and implemented to bring to market an Intelligent Well system designed from day one to maximize system reliability, while offering the customer a high degree of choice in system functionality. A team of engineers and scientists skilled in all aspects of Reliability Analysis and Assessment analyzed the Intelligent Well system under development, gathered reliability performance data from other sources and using various analytical techniques developed matrices of system survival probability estimates for various scenarios. Interaction with the system and design engineers has been an on-going process as designs are modified to maximize reliability predictions and extensive qualification test programs developed from the component to the overall system level. The techniques used in the development project will be presented. A comparative model now exists that facilitates the evaluation of future design alternative considerations and also contains databases that can be readily updated with actual field data etc. (author)

Reliability evaluation of deregulated electric power systems for planning applications

International Nuclear Information System (INIS)

Ehsani, A.; Ranjbar, A.M.; Jafari, A.; Fotuhi-Firuzabad, M.

2008-01-01

In a deregulated electric power utility industry in which a competitive electricity market can influence system reliability, market risks cannot be ignored. This paper (1) proposes an analytical probabilistic model for reliability evaluation of competitive electricity markets and (2) develops a methodology for incorporating the market reliability problem into HLII reliability studies. A Markov state space diagram is employed to evaluate the market reliability. Since the market is a continuously operated system, the concept of absorbing states is applied to it in order to evaluate the reliability. The market states are identified by using market performance indices and the transition rates are calculated by using historical data. The key point in the proposed method is the concept that the reliability level of a restructured electric power system can be calculated using the availability of the composite power system (HLII) and the reliability of the electricity market. Two case studies are carried out over Roy Billinton Test System (RBTS) to illustrate interesting features of the proposed methodology

Design for Reliability in Renewable Energy Systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Zhou, Dao; Sangwongwanich, Ariya

2017-01-01

Power electronics are widely used in renewable energy systems to achieve lower cost of energy, higher efficiency and high power density. At the same time, the high reliability of the power electronics products is demanded, in order to reduce the failure rates and ensure cost-effective operation...... of the renewable energy systems. This paper thus describes the basic concepts used in reliability engineering, and presents the status and future trends of Design for Reliability (DfR) in power electronics, which is currently undergoing a paradigm shift to a physics-of-failure approach. Two case studies of a 2 MW...

Ultra-Reliable Communication in 5G Wireless Systems

DEFF Research Database (Denmark)

Popovski, Petar

2014-01-01

—Wireless 5G systems will not only be “4G, but faster”. One of the novel features discussed in relation to 5G is Ultra-Reliable Communication (URC), an operation mode not present in today’s wireless systems. URC refers to provision of certain level of communication service almost 100 % of the time....... Example URC applications include reliable cloud connectivity, critical connections for industrial automation and reliable wireless coordination among vehicles. This paper puts forward a systematic view on URC in 5G wireless systems. It starts by analyzing the fundamental mechanisms that constitute......-term URC (URC-S). The second dimension is represented by the type of reliability impairment that can affect the communication reliability in a given scenario. The main objective of this paper is to create the context for defining and solving the new engineering problems posed by URC in 5G....

77 FR 7526 - Interpretation of Protection System Reliability Standard

Science.gov (United States)

2012-02-13

... Federal Power Act (FPA) requires a Commission-certified Electric Reliability Organization (ERO) to develop.... Cir. 2009). \\8\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, FERC Stats... a person that is ``directly and materially affected'' by Bulk-Power System reliability may request...

Reliability analysis in interdependent smart grid systems

Science.gov (United States)

Peng, Hao; Kan, Zhe; Zhao, Dandan; Han, Jianmin; Lu, Jianfeng; Hu, Zhaolong

2018-06-01

Complex network theory is a useful way to study many real complex systems. In this paper, a reliability analysis model based on complex network theory is introduced in interdependent smart grid systems. In this paper, we focus on understanding the structure of smart grid systems and studying the underlying network model, their interactions, and relationships and how cascading failures occur in the interdependent smart grid systems. We propose a practical model for interdependent smart grid systems using complex theory. Besides, based on percolation theory, we also study the effect of cascading failures effect and reveal detailed mathematical analysis of failure propagation in such systems. We analyze the reliability of our proposed model caused by random attacks or failures by calculating the size of giant functioning components in interdependent smart grid systems. Our simulation results also show that there exists a threshold for the proportion of faulty nodes, beyond which the smart grid systems collapse. Also we determine the critical values for different system parameters. In this way, the reliability analysis model based on complex network theory can be effectively utilized for anti-attack and protection purposes in interdependent smart grid systems.

GStat 2.0: Grid Information System Status Monitoring

CERN Document Server

Field, L; Tsai, M; CERN. Geneva. IT Department

2010-01-01

Grid Information Systems are mission-critical components in today's production grid infrastructures. They enable users, applications and services to discover which services exist in the infrastructure and further information about the service structure and state. It is therefore important that the information system components themselves are functioning correctly and that the information content is reliable. Grid Status (GStat) is a tool that monitors the structural integrity of the EGEE information system, which is a hierarchical system built out of more than 260 site-level and approximately 70 global aggregation services. It also checks the information content and presents summary and history displays for Grid Operators and System Administrators. A major new version, GStat 2.0, aims to build on the production experience of GStat and provides additional functionality, which enables it to be extended and combined with other tools

The contribution of instrumentation and control software to system reliability

International Nuclear Information System (INIS)

Fryer, M.O.

1984-01-01

Advanced instrumentation and control systems are usually implemented using computers that monitor the instrumentation and issue commands to control elements. The control commands are based on instrument readings and software control logic. The reliability of the total system will be affected by the software design. When comparing software designs, an evaluation of how each design can contribute to the reliability of the system is desirable. Unfortunately, the science of reliability assessment of combined hardware and software systems is in its infancy. Reliability assessment of combined hardware/software systems is often based on over-simplified assumptions about software behavior. A new method of reliability assessment of combined software/hardware systems is presented. The method is based on a procedure called fault tree analysis which determines how component failures can contribute to system failure. Fault tree analysis is a well developed method for reliability assessment of hardware systems and produces quantitative estimates of failure probability based on component failure rates. It is shown how software control logic can be mapped into a fault tree that depicts both software and hardware contributions to system failure. The new method is important because it provides a way for quantitatively evaluating the reliability contribution of software designs. In many applications, this can help guide designers in producing safer and more reliable systems. An application to the nuclear power research industry is discussed

Structural Reliability Methods for Wind Power Converter System Component Reliability Assessment

DEFF Research Database (Denmark)

Kostandyan, Erik; Sørensen, John Dalsgaard

2012-01-01

Wind power converter systems are essential subsystems in both off-shore and on-shore wind turbines. It is the main interface between generator and grid connection. This system is affected by numerous stresses where the main contributors might be defined as vibration and temperature loadings....... The temperature variations induce time-varying stresses and thereby fatigue loads. A probabilistic model is used to model fatigue failure for an electrical component in the power converter system. This model is based on a linear damage accumulation and physics of failure approaches, where a failure criterion...... is defined by the threshold model. The attention is focused on crack propagation in solder joints of electrical components due to the temperature loadings. Structural Reliability approaches are used to incorporate model, physical and statistical uncertainties. Reliability estimation by means of structural...

Toddlers favor communicatively presented information over statistical reliability in learning about artifacts.

Directory of Open Access Journals (Sweden)

Hanna Marno

Full Text Available Observed associations between events can be validated by statistical information of reliability or by testament of communicative sources. We tested whether toddlers learn from their own observation of efficiency, assessed by statistical information on reliability of interventions, or from communicatively presented demonstration, when these two potential types of evidence of validity of interventions on a novel artifact are contrasted with each other. Eighteen-month-old infants observed two adults, one operating the artifact by a method that was more efficient (2/3 probability of success than that of the other (1/3 probability of success. Compared to the Baseline condition, in which communicative signals were not employed, infants tended to choose the less reliable method to operate the artifact when this method was demonstrated in a communicative manner in the Experimental condition. This finding demonstrates that, in certain circumstances, communicative sanctioning of reliability may override statistical evidence for young learners. Such a bias can serve fast and efficient transmission of knowledge between generations.

Reliability modeling of a hard real-time system using the path-space approach

International Nuclear Information System (INIS)

Kim, Hagbae

2000-01-01

A hard real-time system, such as a fly-by-wire system, fails catastrophically (e.g. losing stability) if its control inputs are not updated by its digital controller computer within a certain timing constraint called the hard deadline. To assess and validate those systems' reliabilities by using a semi-Markov model that explicitly contains the deadline information, we propose a path-space approach deriving the upper and lower bounds of the probability of system failure. These bounds are derived by using only simple parameters, and they are especially suitable for highly reliable systems which should recover quickly. Analytical bounds are derived for both exponential and Wobble failure distributions encountered commonly, which have proven effective through numerical examples, while considering three repair strategies: repair-as-good-as-new, repair-as-good-as-old, and repair-better-than-old

Reliability of power electronic converter systems

CERN Document Server

Chung, Henry Shu-hung; Blaabjerg, Frede; Pecht, Michael

2016-01-01

This book outlines current research into the scientific modeling, experimentation, and remedial measures for advancing the reliability, availability, system robustness, and maintainability of Power Electronic Converter Systems (PECS) at different levels of complexity.

Analysis Testing of Sociocultural Factors Influence on Human Reliability within Sociotechnical Systems: The Algerian Oil Companies

Directory of Open Access Journals (Sweden)

Abdelbaki Laidoune

2016-09-01

Conclusion: The explored sociocultural factors influence the human reliability both in qualitative and quantitative manners. The proposed model shows how reliability can be enhanced by some measures such as experience feedback based on, for example, safety improvements, training, and information. With that is added the continuous systems improvements to improve sociocultural reality and to reduce negative behaviors.

Nonparametric predictive inference for reliability of a k-out-of-m:G system with multiple component types

International Nuclear Information System (INIS)

Aboalkhair, Ahmad M.; Coolen, Frank P.A.; MacPhee, Iain M.

2014-01-01

Nonparametric predictive inference for system reliability has recently been presented, with specific focus on k-out-of-m:G systems. The reliability of systems is quantified by lower and upper probabilities of system functioning, given binary test results on components, taking uncertainty about component functioning and indeterminacy due to limited test information explicitly into account. Thus far, systems considered were series configurations of subsystems, with each subsystem i a k i -out-of-m i :G system which consisted of only one type of components. Key results are briefly summarized in this paper, and as an important generalization new results are presented for a single k-out-of-m:G system consisting of components of multiple types. The important aspects of redundancy and diversity for such systems are discussed. - Highlights: • New results on nonparametric predictive inference for system reliability. • Prediction of system reliability based on test data for components. • New insights on system redundancy optimization and diversity. • Components that appear inferior in tests may be included to enhance redundancy

Development in structural systems reliability theory

Energy Technology Data Exchange (ETDEWEB)

Murotsu, Y

1986-07-01

This paper is concerned with two topics on structural systems reliability theory. One covers automatic generation of failure mode equations, identifications of stochastically dominant failure modes, and reliability assessment of redundant structures. Reduced stiffness matrixes and equivalent nodal forces representing the failed elements are introduced for expressing the safety of the elements, using a matrix method. Dominant failure modes are systematically selected by a branch-and-bound technique and heuristic operations. The other discusses the various optimum design problems based on reliability concept. Those problems are interpreted through a solution to a multi-objective optimization problem.

Development in structural systems reliability theory

International Nuclear Information System (INIS)

Murotsu, Y.

1986-01-01

This paper is concerned with two topics on structural systems reliability theory. One covers automatic generation of failure mode equations, identifications of stochastically dominant failure modes, and reliability assessment of redundant structures. Reduced stiffness matrixes and equivalent nodal forces representing the failed elements are introduced for expressing the safety of the elements, using a matrix method. Dominant failure modes are systematically selected by a branch-and-bound technique and heuristic operations. The other discusses the various optimum design problems based on reliability concept. Those problems are interpreted through a solution to a multi-objective optimization problem. (orig.)

Web measurement - a tool to achieve reliable information on custody transfer measurement systems in pipeline operations; Web medicao - uma ferramenta de consolidacao de informacoes sobre sistemas de medicao para transferencia de custodia

Energy Technology Data Exchange (ETDEWEB)

Cid, Eliane Areas; Freitas, Surama de Oliveitra [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Ferreira, Ana Luisa Auler da Silva; Dias, Gerson Vieira [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

2003-07-01

The prompt and organized information about measurement systems is essential for custody transfer in the pipeline transportation business. This organized information can serve as a basis for operational, maintenance and commercial groups in pipeline transportation companies. This information can also help management in planning future improvements in hardware for custody transfer measurements. In nation-wide companies, like TRANSPETRO, information about custody transfer measurement systems, if not organized, will be scattered geographically and organizationally. In organizing this kind of information, distributed systems have a big advantage, with information maintained by operational groups and centralized in the headquarters of the company. This paper describes the implementation of a system for consolidating and updating company information about custody transfer measurement systems for liquid and gas. The system has been implemented on the Intranet, allowing initial data entry in a distributed way, and a centralized validation by the headquarters engineering group. The new methodology has sharply increased the reliability in the information of custody transfer measurement systems in the company. (author)

Reliability and durability in solar energy systems

Energy Technology Data Exchange (ETDEWEB)

Godolphin, D.

1982-10-01

The reliability and durability in solar energy systems for residential buildings is discussed. It is concluded that although strides have been made in design and manufacturing over the past years, the reliability and durability of the equipment depends on the proper installation. (MJF)

Reliability and Validity of Curriculum-Based Informal Reading Inventories.

Science.gov (United States)

Fuchs, Lynn; And Others

A study was conducted to explore the reliability and validity of three prominent procedures used in informal reading inventories (IRIs): (1) choosing a 95% word recognition accuracy standard for determining student instructional level, (2) arbitrarily selecting a passage to represent the difficulty level of a basal reader, and (3) employing…

Availability estimation of repairable systems using reliability graph with general gates (RGGG)

International Nuclear Information System (INIS)

Goh, Gyoung Tae

2009-02-01

By performing risk analysis, we may obtain sufficient information about the system to redesign it and lower the probability of the occurrence of an accident or mitigate the ensuing consequences. The concept of reliability is widely used to express risk of systems. The reliability is used for non-repairable systems. But nuclear power plant systems are repairable systems. With repairable systems, repairable components can improve the availability of a system because faults that are generated in components can be recovered. Hence, the availability of the system is more proper concept in case of repairable systems. Reliability graph with general gate (RGGG) is one of the system reliability analysis methods. The RGGG is a very intuitiveness method as compared with other methods. But the RGGG has not been applied to repairable systems yet. The objective of this study is to extend the RGGG in order to enable one to analyze repairable system. Determining the probability table for each node is a critical process to calculate the system availability in the RGGG method. Therefore finding the proper algorithms and making probability tables in various situations are the major a part of this study. The other part is an example of applying RGGG method to a real system. We find the proper algorithms and probability tables for independent repairable systems, dependent series repairable systems, and k-out-of-m (K/M) redundant parallel repairable systems in this study. We can evaluate the availability of real system using these probability tables. An example for a real system is shown in the latter part of this study. For the purpose of this analysis, the charging pumps subsystem of the chemical and volume control system (CVCS) was selected. The RGGG method extended for repairable systems has the same characteristic of intuitiveness as the original RGGG method and we can confirm that the availability analysis result from the repairable RGGG method is exact

System reliability evaluation of a touch panel manufacturing system with defect rate and reworking

International Nuclear Information System (INIS)

Lin, Yi-Kuei; Huang, Cheng-Fu; Chang, Ping-Chen

2013-01-01

In recent years, portable consumer electronic products, such as cell phone, GPS, digital camera, tablet PC, and notebook are using touch panel as interface. With the demand of touch panel increases, performance assessment is essential for touch panel production. This paper develops a method to evaluate system reliability of a touch panel manufacturing system (TPMS) with defect rate of each workstation and takes reworking actions into account. The system reliability which evaluates the possibility of demand satisfaction can provide to managers with an understanding of the system capability and can indicate possible improvements. First, we construct a capacitated manufacturing network (CMN) for a TPMS. Second, a decomposition technique is developed to determine the input flow of each workstation based on the CMN. Finally, we generate the minimal capacity vectors that should be provided to satisfy the demand. The system reliability is subsequently evaluated in terms of the minimal capacity vectors. A further decision making issue is discussed to decide a reliable production strategy. -- Graphical abstract: The proposed procedure to evaluate system reliability of the touch panel manufacturing system (TPMS). Highlights: • The system reliability of a touch panel manufacturing system (TPMS) is evaluated. • The reworking actions are taken into account in the TPMS. • A capacitated manufacturing network is constructed for the TPMS. • A procedure is proposed to evaluate system reliability of TPMS

Statistical reliability assessment of software-based systems

International Nuclear Information System (INIS)

Korhonen, J.; Pulkkinen, U.; Haapanen, P.

1997-01-01

Plant vendors nowadays propose software-based systems even for the most critical safety functions. The reliability estimation of safety critical software-based systems is difficult since the conventional modeling techniques do not necessarily apply to the analysis of these systems, and the quantification seems to be impossible. Due to lack of operational experience and due to the nature of software faults, the conventional reliability estimation methods can not be applied. New methods are therefore needed for the safety assessment of software-based systems. In the research project Programmable automation systems in nuclear power plants (OHA), financed together by the Finnish Centre for Radiation and Nuclear Safety (STUK), the Ministry of Trade and Industry and the Technical Research Centre of Finland (VTT), various safety assessment methods and tools for software based systems are developed and evaluated. This volume in the OHA-report series deals with the statistical reliability assessment of software based systems on the basis of dynamic test results and qualitative evidence from the system design process. Other reports to be published later on in OHA-report series will handle the diversity requirements in safety critical software-based systems, generation of test data from operational profiles and handling of programmable automation in plant PSA-studies. (orig.) (25 refs.)

Preparation of methodology for reliability analysis of selected digital segments of the instrumentation and control systems of NPPs. Pt. 1

International Nuclear Information System (INIS)

Hustak, S.; Patrik, M.; Babic, P.

2000-12-01

The report is structured as follows: (i) Introduction; (ii) Important notions relating to the safety and dependability of software systems for nuclear power plants (selected notions from IAEA Technical Report No. 397; safety aspects of software application; reliability/dependability aspects of digital systems); (iii) Peculiarities of digital systems and ways to a dependable performance of the required function (failures in the system and principles of defence against them; ensuring resistance of digital systems against failures at various hardware and software levels); (iv) The issue of analytical procedures to assess the safety and reliability of safety-related digital systems (safety and reliability assessment at an early stage of the project; general framework of reliability analysis of complex systems; choice of an appropriate quantitative measure of software reliability); (v) Selected qualitative and quantitative information about the reliability of digital systems; the use of relations between the incidence of various types of faults); and (vi) Conclusions and recommendations. (P.A.)

Reliability prediction of engineering systems with competing failure modes due to component degradation

International Nuclear Information System (INIS)

Son, Young Kap

2011-01-01

Reliability of an engineering system depends on two reliability metrics: the mechanical reliability, considering component failures, that a functional system topology is maintained and the performance reliability of adequate system performance in each functional configuration. Component degradation explains not only the component aging processes leading to failure in function, but also system performance change over time. Multiple competing failure modes for systems with degrading components in terms of system functionality and system performance are considered in this paper with the assumption that system functionality is not independent of system performance. To reduce errors in system reliability prediction, this paper tries to extend system performance reliability prediction methods in open literature through combining system mechanical reliability from component reliabilities and system performance reliability. The extended reliability prediction method provides a useful way to compare designs as well as to determine effective maintenance policy for efficient reliability growth. Application of the method to an electro-mechanical system, as an illustrative example, is explained in detail, and the prediction results are discussed. Both mechanical reliability and performance reliability are compared to total system reliability in terms of reliability prediction errors

Human reliability

International Nuclear Information System (INIS)

Bubb, H.

1992-01-01

This book resulted from the activity of Task Force 4.2 - 'Human Reliability'. This group was established on February 27th, 1986, at the plenary meeting of the Technical Reliability Committee of VDI, within the framework of the joint committee of VDI on industrial systems technology - GIS. It is composed of representatives of industry, representatives of research institutes, of technical control boards and universities, whose job it is to study how man fits into the technical side of the world of work and to optimize this interaction. In a total of 17 sessions, information from the part of ergonomy dealing with human reliability in using technical systems at work was exchanged, and different methods for its evaluation were examined and analyzed. The outcome of this work was systematized and compiled in this book. (orig.) [de

Mathematical reliability an expository perspective

CERN Document Server

Mazzuchi, Thomas; Singpurwalla, Nozer

2004-01-01

In this volume consideration was given to more advanced theoretical approaches and novel applications of reliability to ensure that topics having a futuristic impact were specifically included. Topics like finance, forensics, information, and orthopedics, as well as the more traditional reliability topics were purposefully undertaken to make this collection different from the existing books in reliability. The entries have been categorized into seven parts, each emphasizing a theme that seems poised for the future development of reliability as an academic discipline with relevance. The seven parts are networks and systems; recurrent events; information and design; failure rate function and burn-in; software reliability and random environments; reliability in composites and orthopedics, and reliability in finance and forensics. Embedded within the above are some of the other currently active topics such as causality, cascading, exchangeability, expert testimony, hierarchical modeling, optimization and survival...

Distribution system reliability evaluation using credibility theory | Xu ...

African Journals Online (AJOL)

In this paper, a hybrid algorithm based on fuzzy simulation and Failure Mode and Effect Analysis (FMEA) is applied to determine fuzzy reliability indices of distribution system. This approach can obtain fuzzy expected values and their variances of reliability indices, and the credibilities of reliability indices meeting specified ...

Evolving Reliability and Maintainability Allocations for NASA Ground Systems

Science.gov (United States)

Munoz, Gisela; Toon, T.; Toon, J.; Conner, A.; Adams, T.; Miranda, D.

2016-01-01

This paper describes the methodology and value of modifying allocations to reliability and maintainability requirements for the NASA Ground Systems Development and Operations (GSDO) programs subsystems. As systems progressed through their design life cycle and hardware data became available, it became necessary to reexamine the previously derived allocations. This iterative process provided an opportunity for the reliability engineering team to reevaluate allocations as systems moved beyond their conceptual and preliminary design phases. These new allocations are based on updated designs and maintainability characteristics of the components. It was found that trade-offs in reliability and maintainability were essential to ensuring the integrity of the reliability and maintainability analysis. This paper discusses the results of reliability and maintainability reallocations made for the GSDO subsystems as the program nears the end of its design phase.

Reliability analysis and initial requirements for FC systems and stacks

Science.gov (United States)

Åström, K.; Fontell, E.; Virtanen, S.

In the year 2000 Wärtsilä Corporation started an R&D program to develop SOFC systems for CHP applications. The program aims to bring to the market highly efficient, clean and cost competitive fuel cell systems with rated power output in the range of 50-250 kW for distributed generation and marine applications. In the program Wärtsilä focuses on system integration and development. System reliability and availability are key issues determining the competitiveness of the SOFC technology. In Wärtsilä, methods have been implemented for analysing the system in respect to reliability and safety as well as for defining reliability requirements for system components. A fault tree representation is used as the basis for reliability prediction analysis. A dynamic simulation technique has been developed to allow for non-static properties in the fault tree logic modelling. Special emphasis has been placed on reliability analysis of the fuel cell stacks in the system. A method for assessing reliability and critical failure predictability requirements for fuel cell stacks in a system consisting of several stacks has been developed. The method is based on a qualitative model of the stack configuration where each stack can be in a functional, partially failed or critically failed state, each of the states having different failure rates and effects on the system behaviour. The main purpose of the method is to understand the effect of stack reliability, critical failure predictability and operating strategy on the system reliability and availability. An example configuration, consisting of 5 × 5 stacks (series of 5 sets of 5 parallel stacks) is analysed in respect to stack reliability requirements as a function of predictability of critical failures and Weibull shape factor of failure rate distributions.

Major factors in critical equipment reliability - Auxiliary systems; The development of an auxiliary system

International Nuclear Information System (INIS)

Forsthoffer, W.E.

1992-01-01

In this article, the author details the development of an actual auxiliary system in order to fully understand the function of each major component and how it contributes to the total operation and reliability of the system. Only after the function of an auxiliary system is thoroughly understood, can one proceed to discuss specifications, design audits, testing, operation and preventive maintenance. The application selected will be to develop a pressurized lubrication and steam turbine control oil system for the critical equipment unit. This example was selected since many readers will be familiar with this type and because it provides a good foundation towards understanding fluid sealing systems. In the exercise that follow, he will define the system requirements and determine the system parameters. This information will then be used for component sizing

Reliability issues of free-space communications systems and networks

Science.gov (United States)

Willebrand, Heinz A.

2003-04-01

Free space optics (FSO) is a high-speed point-to-point connectivity solution traditionally used in the enterprise campus networking market for building-to-building LAN connectivity. However, more recently some wire line and wireless carriers started to deploy FSO systems in their networks. The requirements on FSO system reliability, meaing both system availability and component reliability, are far more stringent in the carrier market when compared to the requirements in the enterprise market segment. This paper tries to outline some of the aspects that are important to ensure carrier class system reliability.

Innovations in power systems reliability

CERN Document Server

Santora, Albert H; Vaccaro, Alfredo

2011-01-01

Electrical grids are among the world's most reliable systems, yet they still face a host of issues, from aging infrastructure to questions of resource distribution. Here is a comprehensive and systematic approach to tackling these contemporary challenges.

Interrater reliability of a Pilates movement-based classification system.

Science.gov (United States)

Yu, Kwan Kenny; Tulloch, Evelyn; Hendrick, Paul

2015-01-01

To determine the interrater reliability for identification of a specific movement pattern using a Pilates Classification system. Videos of 5 subjects performing specific movement tasks were sent to raters trained in the DMA-CP classification system. Ninety-six raters completed the survey. Interrater reliability for the detection of a directional bias was excellent (Pi = 0.92, and K(free) = 0.89). Interrater reliability for classifying an individual into a specific subgroup was moderate (Pi = 0.64, K(free) = 0.55) however raters who had completed levels 1-4 of the DMA-CP training and reported using the assessment daily demonstrated excellent reliability (Pi = 0.89 and K(free) = 0.87). The reliability of the classification system demonstrated almost perfect agreement in determining the existence of a specific movement pattern and classifying into a subgroup for experienced raters. There was a trend for greater reliability associated with increased levels of training and experience of the raters. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Review: Passive System Reliability Analysis – Accomplishments and Unresolved Issues

Energy Technology Data Exchange (ETDEWEB)

Nayak, Arun Kumar, E-mail: arunths@barc.gov.in [Reactor Engineering Division, Reactor Design and Development Group, Bhabha Atomic Research Centre, Mumbai (India); Chandrakar, Amit [Homi Bhabha National Institute, Mumbai (India); Vinod, Gopika [Reactor Safety Division, Reactor Design and Development Group, Bhabha Atomic Research Centre, Mumbai (India)

2014-10-10

Reliability assessment of passive safety systems is one of the important issues, since safety of advanced nuclear reactors rely on several passive features. In this context, a few methodologies such as reliability evaluation of passive safety system (REPAS), reliability methods for passive safety functions (RMPS), and analysis of passive systems reliability (APSRA) have been developed in the past. These methodologies have been used to assess reliability of various passive safety systems. While these methodologies have certain features in common, but they differ in considering certain issues; for example, treatment of model uncertainties, deviation of geometric, and process parameters from their nominal values. This paper presents the state of the art on passive system reliability assessment methodologies, the accomplishments, and remaining issues. In this review, three critical issues pertaining to passive systems performance and reliability have been identified. The first issue is applicability of best estimate codes and model uncertainty. The best estimate codes based phenomenological simulations of natural convection passive systems could have significant amount of uncertainties, these uncertainties must be incorporated in appropriate manner in the performance and reliability analysis of such systems. The second issue is the treatment of dynamic failure characteristics of components of passive systems. REPAS, RMPS, and APSRA methodologies do not consider dynamic failures of components or process, which may have strong influence on the failure of passive systems. The influence of dynamic failure characteristics of components on system failure probability is presented with the help of a dynamic reliability methodology based on Monte Carlo simulation. The analysis of a benchmark problem of Hold-up tank shows the error in failure probability estimation by not considering the dynamism of components. It is thus suggested that dynamic reliability methodologies must be

Reliability of fossil-fuel and nuclear power installations

International Nuclear Information System (INIS)

1983-01-01

The conference heard a total of 37 papers of which 24 were inputted in INIS. The subject area was mainly the use of reliability information systems and the production of data banks for these systems, the application of the reliability theory and the reliability analysis of equipment and systems of nuclear power plants. (J.P.)

Reliability Issues in Stirling Radioisotope Power Systems

Science.gov (United States)

Schreiber, Jeffrey; Shah, Ashwin

2005-01-01

Stirling power conversion is a potential candidate for use in a Radioisotope Power System (RPS) for space science missions because it offers a multifold increase in the conversion efficiency of heat to electric power and reduced requirement of radioactive material. Reliability of an RPS that utilizes Stirling power conversion technology is important in order to ascertain long term successful performance. Owing to long life time requirement (14 years), it is difficult to perform long-term tests that encompass all the uncertainties involved in the design variables of components and subsystems comprising the RPS. The requirement for uninterrupted performance reliability and related issues are discussed, and some of the critical areas of concern are identified. An overview of the current on-going efforts to understand component life, design variables at the component and system levels, and related sources and nature of uncertainties are also discussed. Current status of the 110 watt Stirling Radioisotope Generator (SRG110) reliability efforts is described. Additionally, an approach showing the use of past experience on other successfully used power systems to develop a reliability plan for the SRG110 design is outlined.

Proceedings of the Digital Systems Reliability and Nuclear Safety Workshop

Energy Technology Data Exchange (ETDEWEB)

Wallace, D. R.; Cuthill, B. B.; Ippolito, L. M. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Beltracchi, L. [Nuclear Regulatory Commission, Washington, DC (United States) ed.

1994-03-01

The United States Nuclear Regulatory Commission (NRC), in cooperation with the National Institute of Standards and Technology conducted the.Digital Systems Reliability and Nuclear Safety Workshop on September 13--14, 1993, in Rockville, Maryland. The workshop provided a forum for the exchange of information among experts within the nuclear industry, experts from other industries, regulators and academia. The information presented at this workshop provided in-depth exposure of the NRC staff and the nuclear industry to digital systems design safety issues and also provided feedback to the NRC from outside experts regarding identified safety issues, proposed regulatory positions, and intended research associated with the use of digital systems in nuclear power plants. Technical presentations provided insights on areas where current software engineering practices may be inadequate for safety-critical systems, on potential solutions for development issues, and on methods for reducing risk in safety-critical systems. This report contains an analysis of results of the workshop, the papers presented panel presentations, and summaries of, discussions at this workshop. The individual papers have been cataloged separately.

Final Report for the Virtual Reliability Realization System LDRD

Energy Technology Data Exchange (ETDEWEB)

DELLIN, THEODORE A.; HENDERSON, CHRISTOPHER L.; O' TOOLE, EDWARD J.

2000-12-01

Current approaches to reliability are not adequate to keep pace with the need for faster, better and cheaper products and systems. This is especially true in high consequence of failure applications. The original proposal for the LDRD was to look at this challenge and see if there was a new paradigm that could make reliability predictions, along with a quantitative estimate of the risk in that prediction, in a way that was faster, better and cheaper. Such an approach would be based on the underlying science models that are the backbone of reliability predictions. The new paradigm would be implemented in two software tools: the Virtual Reliability Realization System (VRRS) and the Reliability Expert System (REX). The three-year LDRD was funded at a reduced level for the first year ($120K vs. $250K) and not renewed. Because of the reduced funding, we concentrated on the initial development of the expertise system. We developed an interactive semiconductor calculation tool needed for reliability analyses. We also were able to generate a basic functional system using Microsoft Siteserver Commerce Edition and Microsoft Sequel Server. The base system has the capability to store Office documents from multiple authors, and has the ability to track and charge for usage. The full outline of the knowledge model has been incorporated as well as examples of various types of content.

Reliability modelling of repairable systems using Petri nets and fuzzy Lambda-Tau methodology

International Nuclear Information System (INIS)

Knezevic, J.; Odoom, E.R.

2001-01-01

A methodology is developed which uses Petri nets instead of the fault tree methodology and solves for reliability indices utilising fuzzy Lambda-Tau method. Fuzzy set theory is used for representing the failure rate and repair time instead of the classical (crisp) set theory because fuzzy numbers allow expert opinions, linguistic variables, operating conditions, uncertainty and imprecision in reliability information to be incorporated into the system model. Petri nets are used because unlike the fault tree methodology, the use of Petri nets allows efficient simultaneous generation of minimal cut and path sets

System Reliability for LED-Based Products

Energy Technology Data Exchange (ETDEWEB)

Davis, J Lynn; Mills, Karmann; Lamvik, Michael; Yaga, Robert; Shepherd, Sarah D; Bittle, James; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy; Johnson, Cortina; Evans, Amy

2014-04-07

Results from accelerated life tests (ALT) on mass-produced commercially available 6” downlights are reported along with results from commercial LEDs. The luminaires capture many of the design features found in modern luminaires. In general, a systems perspective is required to understand the reliability of these devices since LED failure is rare. In contrast, components such as drivers, lenses, and reflector are more likely to impact luminaire reliability than LEDs.

Role of information systems in public health services.

Science.gov (United States)

Hartshorne, J E; Carstens, I L

1990-07-01

The purpose of this review is to establish a conceptual framework on the role of information systems in public health care. Information is indispensable for effective management and development of health services and therefore considered as an important operational asset or resource. A Health Information System is mainly required to support management and operations at four levels: namely transactional and functional; operational control; management planning and control; and strategic planning. To provide the necessary information needs of users at these levels of management in the health care system, a structured information system coupled with appropriate information technology is required. Adequate and relevant information is needed regarding population characteristics, resources available and expended, output and outcome of health care activities. Additionally information needs to be reliable, accurate, timely, easily accessible and presented in a compact and meaningful form. With a well-planned health information system health authorities would be in a position to provide a quality, cost-effective and efficient health service for as many people as need it, optimal utilisation of resources and to maintain and improve the community's health status.

The information system of the Spanish nuclear power plants: DACNE

International Nuclear Information System (INIS)

Diez M, Jose E.

1995-01-01

DACNE information system is a set of two databases aimed at collecting and retrieving information related to operation of the Spanish nuclear power plants. The first one is the Operation Events Database and the second is the Reliability Components Database. The system was designed and developed by UNESA and came into operation early in 1989. A significant amount of data is currently stored in the system available for information exchange and for supporting operational programs. (author). 6 figs., 4 tabs

Mission reliability of semi-Markov systems under generalized operational time requirements

International Nuclear Information System (INIS)

Wu, Xiaoyue; Hillston, Jane

2015-01-01

Mission reliability of a system depends on specific criteria for mission success. To evaluate the mission reliability of some mission systems that do not need to work normally for the whole mission time, two types of mission reliability for such systems are studied. The first type corresponds to the mission requirement that the system must remain operational continuously for a minimum time within the given mission time interval, while the second corresponds to the mission requirement that the total operational time of the system within the mission time window must be greater than a given value. Based on Markov renewal properties, matrix integral equations are derived for semi-Markov systems. Numerical algorithms and a simulation procedure are provided for both types of mission reliability. Two examples are used for illustration purposes. One is a one-unit repairable Markov system, and the other is a cold standby semi-Markov system consisting of two components. By the proposed approaches, the mission reliability of systems with time redundancy can be more precisely estimated to avoid possible unnecessary redundancy of system resources. - Highlights: • Two types of mission reliability under generalized requirements are defined. • Equations for both types of reliability are derived for semi-Markov systems. • Numerical methods are given for solving both types of reliability. • Simulation procedure is given for estimating both types of reliability. • Verification of the numerical methods is given by the results of simulation

Under Construction: Reviewing and Producing Information Reliability on the Web

NARCIS (Netherlands)

S.A. Adams (Samantha)

2006-01-01

textabstractSince 1995, medical professionals, governments and independent organizations have been developing special tools to help lay-persons find websites that are guaranteed to give only reliable medical or health-related information. However, as these different actors also recognize, such a

Optimization of Reliability and Power Consumption in Systems on a Chip

OpenAIRE

Simunic, Tajana; Mihic, Kresimir; De Micheli, Giovanni

2005-01-01

Aggressive transistor scaling, decreased voltage margins and increased processor power and temperature, have made reliability assessment a much more significant issue in design. Although reliability of devices and interconnect has been broadly studied, here we characterize reliability at the system level. Thus we consider component-based System on Chip designs. Reliability is strongly affected by system temperature, which is in turn driven by power consumption. Thus, component reliability and...

Maximising water supply system yield subject to multiple reliability ...

African Journals Online (AJOL)

Maximising water supply system yield subject to multiple reliability constraints via simulation-optimisation. ... Water supply systems have to satisfy different demands that each require various levels of reliability ... and monthly operating rules that maximise the yield of a water supply system subject to ... HOW TO USE AJOL.

Information for the user in design of intelligent systems

Science.gov (United States)

Malin, Jane T.; Schreckenghost, Debra L.

1993-01-01

Recommendations are made for improving intelligent system reliability and usability based on the use of information requirements in system development. Information requirements define the task-relevant messages exchanged between the intelligent system and the user by means of the user interface medium. Thus, these requirements affect the design of both the intelligent system and its user interface. Many difficulties that users have in interacting with intelligent systems are caused by information problems. These information problems result from the following: (1) not providing the right information to support domain tasks; and (2) not recognizing that using an intelligent system introduces new user supervisory tasks that require new types of information. These problems are especially prevalent in intelligent systems used for real-time space operations, where data problems and unexpected situations are common. Information problems can be solved by deriving information requirements from a description of user tasks. Using information requirements embeds human-computer interaction design into intelligent system prototyping, resulting in intelligent systems that are more robust and easier to use.

An analytical framework for reliability growth of one-shot systems

International Nuclear Information System (INIS)

Hall, J. Brian; Mosleh, Ali

2008-01-01

In this paper, we introduce a new reliability growth methodology for one-shot systems that is applicable to the case where all corrective actions are implemented at the end of the current test phase. The methodology consists of four model equations for assessing: expected reliability, the expected number of failure modes observed in testing, the expected probability of discovering new failure modes, and the expected portion of system unreliability associated with repeat failure modes. These model equations provide an analytical framework for which reliability practitioners can estimate reliability improvement, address goodness-of-fit concerns, quantify programmatic risk, and assess reliability maturity of one-shot systems. A numerical example is given to illustrate the value and utility of the presented approach. This methodology is useful to program managers and reliability practitioners interested in applying the techniques above in their reliability growth program

Intra- and Interobserver Reliability of Three Classification Systems for Hallux Rigidus.

Science.gov (United States)

Dillard, Sarita; Schilero, Christina; Chiang, Sharon; Pham, Peter

2018-04-18

There are over ten classification systems currently used in the staging of hallux rigidus. This results in confusion and inconsistency with radiographic interpretation and treatment. The reliability of hallux rigidus classification systems has not yet been tested. The purpose of this study was to evaluate intra- and interobserver reliability using three commonly used classifications for hallux rigidus. Twenty-one plain radiograph sets were presented to ten ACFAS board-certified foot and ankle surgeons. Each physician classified each radiograph based on clinical experience and knowledge according to the Regnauld, Roukis, and Hattrup and Johnson classification systems. The two-way mixed single-measure consistency intraclass correlation was used to calculate intra- and interrater reliability. The intrarater reliability of individual sets for the Roukis and Hattrup and Johnson classification systems was "fair to good" (Roukis, 0.62±0.19; Hattrup and Johnson, 0.62±0.28), whereas the intrarater reliability of individual sets for the Regnauld system bordered between "fair to good" and "poor" (0.43±0.24). The interrater reliability of the mean classification was "excellent" for all three classification systems. Conclusions Reliable and reproducible classification systems are essential for treatment and prognostic implications in hallux rigidus. In our study, Roukis classification system had the best intrarater reliability. Although there are various classification systems for hallux rigidus, our results indicate that all three of these classification systems show reliability and reproducibility.

Reliability analysis of safety systems of nuclear power plant and utility experience with reliability safeguarding of systems during specified normal operation

International Nuclear Information System (INIS)

Balfanz, H.P.

1989-01-01

The paper gives an outline of the methods applied for reliability analysis of safety systems in nuclear power plant. The main tasks are to check the system design for detection of weak points, and to find possibilities of optimizing the strategies for inspection, inspection intervals, maintenance periods. Reliability safeguarding measures include the determination and verification of the broundary conditions of the analysis with regard to the reliability parameters and maintenance parameters used in the analysis, and the analysis of data feedback reflecting the plant response during operation. (orig.) [de

Development of Probabilistic Reliability Models of Photovoltaic System Topologies for System Adequacy Evaluation

Directory of Open Access Journals (Sweden)

Ahmad Alferidi

2017-02-01

Full Text Available The contribution of solar power in electric power systems has been increasing rapidly due to its environmentally friendly nature. Photovoltaic (PV systems contain solar cell panels, power electronic converters, high power switching and often transformers. These components collectively play an important role in shaping the reliability of PV systems. Moreover, the power output of PV systems is variable, so it cannot be controlled as easily as conventional generation due to the unpredictable nature of weather conditions. Therefore, solar power has a different influence on generating system reliability compared to conventional power sources. Recently, different PV system designs have been constructed to maximize the output power of PV systems. These different designs are commonly adopted based on the scale of a PV system. Large-scale grid-connected PV systems are generally connected in a centralized or a string structure. Central and string PV schemes are different in terms of connecting the inverter to PV arrays. Micro-inverter systems are recognized as a third PV system topology. It is therefore important to evaluate the reliability contribution of PV systems under these topologies. This work utilizes a probabilistic technique to develop a power output model for a PV generation system. A reliability model is then developed for a PV integrated power system in order to assess the reliability and energy contribution of the solar system to meet overall system demand. The developed model is applied to a small isolated power unit to evaluate system adequacy and capacity level of a PV system considering the three topologies.

Multicriterial optimization of preventive maintenance of informational/technical stochastic system

Directory of Open Access Journals (Sweden)

Kovalenko Anna

2016-01-01

Full Text Available The problem of optimization of reliability and economical indexes is solved for informational/technical system with periodical diagnostics and restoration. The system considered is the one with users accesses and errors occurring. The probability that the error occurs increases in time. Therefore, the longer is the restoration period the more there is a risk of system operation with error. But too frequent restoration can be too expensive. To take into account all these factors two-criteria optimization is made with the restriction of reliability characteristic being of the given level.

Sustainable, Reliable Mission-Systems Architecture

Science.gov (United States)

O'Neil, Graham; Orr, James K.; Watson, Steve

2007-01-01

A mission-systems architecture, based on a highly modular infrastructure utilizing: open-standards hardware and software interfaces as the enabling technology is essential for affordable and sustainable space exploration programs. This mission-systems architecture requires (a) robust communication between heterogeneous system, (b) high reliability, (c) minimal mission-to-mission reconfiguration, (d) affordable development, system integration, and verification of systems, and (e) minimal sustaining engineering. This paper proposes such an architecture. Lessons learned from the Space Shuttle program and Earthbound complex engineered system are applied to define the model. Technology projections reaching out 5 years are mde to refine model details.

Reliability Evaluation and Improvement Approach of Chemical Production Man - Machine - Environment System

Science.gov (United States)

Miao, Yongchun; Kang, Rongxue; Chen, Xuefeng

2017-12-01

In recent years, with the gradual extension of reliability research, the study of production system reliability has become the hot topic in various industries. Man-machine-environment system is a complex system composed of human factors, machinery equipment and environment. The reliability of individual factor must be analyzed in order to gradually transit to the research of three-factor reliability. Meanwhile, the dynamic relationship among man-machine-environment should be considered to establish an effective blurry evaluation mechanism to truly and effectively analyze the reliability of such systems. In this paper, based on the system engineering, fuzzy theory, reliability theory, human error, environmental impact and machinery equipment failure theory, the reliabilities of human factor, machinery equipment and environment of some chemical production system were studied by the method of fuzzy evaluation. At last, the reliability of man-machine-environment system was calculated to obtain the weighted result, which indicated that the reliability value of this chemical production system was 86.29. Through the given evaluation domain it can be seen that the reliability of man-machine-environment integrated system is in a good status, and the effective measures for further improvement were proposed according to the fuzzy calculation results.

System reliability, performance and trust in adaptable automation.

Science.gov (United States)

Chavaillaz, Alain; Wastell, David; Sauer, Jürgen

2016-01-01

The present study examined the effects of reduced system reliability on operator performance and automation management in an adaptable automation environment. 39 operators were randomly assigned to one of three experimental groups: low (60%), medium (80%), and high (100%) reliability of automation support. The support system provided five incremental levels of automation which operators could freely select according to their needs. After 3 h of training on a simulated process control task (AutoCAMS) in which the automation worked infallibly, operator performance and automation management were measured during a 2.5-h testing session. Trust and workload were also assessed through questionnaires. Results showed that although reduced system reliability resulted in lower levels of trust towards automation, there were no corresponding differences in the operators' reliance on automation. While operators showed overall a noteworthy ability to cope with automation failure, there were, however, decrements in diagnostic speed and prospective memory with lower reliability. Copyright © 2015. Published by Elsevier Ltd.

Information system fur the management of a regulatory programme

International Nuclear Information System (INIS)

Ortiz, P.; Mrabit, K.; Miaw, S.

1998-01-01

A Regulatory Programme to monitor safety of activities involving radiation sources, implies the existence of a Regulatory Authority empowered by legislation to issue radiation protection regulations and to monitor compliance with those regulations. The core element of the programme is a system of notification and authorization (registration and licensing), inspection and enforcement. The efficiency of this system is largely dependent on the availability of reliable information on the inventory of radiation sources and installations, the administrative status of the facilities (authorization), prompt processing of inspection reports and follow up of regulatory actions, including monitoring deadlines. Essential data relevant to safety, such as personal dosimetry for occupationally exposed individuals, inspection findings and incident reports would provide, in addition, an insight on the overall safety of the country. A simple but comprehensive Regulatory Authority Information System (RAIS) linked to the authorization and inspection process will largely facilitate regulatory decisions and actions. A readily available and reliable information from the various regulatory activities will facilitate planning, optimization of resources, monitoring safety related data, disseminating safety information, making decisions and follow up regulatory actions including monitoring dead lines. The implementation of the system in more than 50 countries will contribute to experience exchange and harmonization of regulatory activities. (author)

Reliability Standards of Complex Engineering Systems

Science.gov (United States)

Galperin, E. M.; Zayko, V. A.; Gorshkalev, P. A.

2017-11-01

Production and manufacture play an important role in today’s modern society. Industrial production is nowadays characterized by increased and complex communications between its parts. The problem of preventing accidents in a large industrial enterprise becomes especially relevant. In these circumstances, the reliability of enterprise functioning is of particular importance. Potential damage caused by an accident at such enterprise may lead to substantial material losses and, in some cases, can even cause a loss of human lives. That is why industrial enterprise functioning reliability is immensely important. In terms of their reliability, industrial facilities (objects) are divided into simple and complex. Simple objects are characterized by only two conditions: operable and non-operable. A complex object exists in more than two conditions. The main characteristic here is the stability of its operation. This paper develops the reliability indicator combining the set theory methodology and a state space method. Both are widely used to analyze dynamically developing probability processes. The research also introduces a set of reliability indicators for complex technical systems.

Impact of Advanced Alarm Systems and Information Displays on Human Reliability in the Digital Control Room of Nuclear Power Plants

International Nuclear Information System (INIS)

Kim, Jong Hyun; Dang, Vinh N

2011-01-01

This paper discusses the potential impacts of two advanced features of digital control rooms, alarm systems and information display systems, on the Human Reliability Analysis (HRA) in nuclear power plants. Although the features of digital control rooms have already been implemented in new or upgraded nuclear power plants, HRAs have so far not taken much credit for these features. In this circumstance, this paper aims at examining the potential effects of these features on human performance and discussing how these effects can be addressed with existing HRA methods. A conclusion derivable from past experimental studies is that those features are supportive in the severe conditions such as complex scenarios and knowledge-based works. However, in the less complex scenarios and rule-based work, they may have no difference with or sometimes negative impacts on operator performance. The discussion about the impact on the HRA is provided on the basis on the THERP method

Research on Connection and Function Reliability of the Oil＆Gas Pipeline System

Directory of Open Access Journals (Sweden)

Xu Bo

2017-01-01

Full Text Available Pipeline transportation is the optimal way for energy delivery in terms of safety, efficiency and environmental protection. Because of the complexity of pipeline external system including geological hazards, social and cultural influence, it is a great challenge to operate the pipeline safely and reliable. Therefore, the pipeline reliability becomes an important issue. Based on the classical reliability theory, the analysis of pipeline system is carried out, then the reliability model of the pipeline system is built, and the calculation is addressed thereafter. Further the connection and function reliability model is applied to a practical active pipeline system, with the use of the proposed methodology of the pipeline system; the connection reliability and function reliability are obtained. This paper firstly presented to considerate the connection and function reliability separately and obtain significant contribution to establish the mathematical reliability model of pipeline system, hence provide fundamental groundwork for the pipeline reliability research in the future.

Reliability analysis of wind embedded power generation system for ...

African Journals Online (AJOL)

This paper presents a method for Reliability Analysis of wind energy embedded in power generation system for Indian scenario. This is done by evaluating the reliability index, loss of load expectation, for the power generation system with and without integration of wind energy sources in the overall electric power system.

Reliability-oriented energy storage sizing in wind power systems

DEFF Research Database (Denmark)

Qin, Zian; Liserre, Marco; Blaabjerg, Frede

2014-01-01

Energy storage can be used to suppress the power fluctuations in wind power systems, and thereby reduce the thermal excursion and improve the reliability. Since the cost of the energy storage in large power application is high, it is crucial to have a better understanding of the relationship...... between the size of the energy storage and the reliability benefit it can generate. Therefore, a reliability-oriented energy storage sizing approach is proposed for the wind power systems, where the power, energy, cost and the control strategy of the energy storage are all taken into account....... With the proposed approach, the computational effort is reduced and the impact of the energy storage system on the reliability of the wind power converter can be quantified....

Development of high-reliability control system for nuclear power plants

International Nuclear Information System (INIS)

Asami, K.; Yanai, K.; Hirose, H.; Ito, T.

1983-01-01

In Japan, many nuclear power generating plants are in operation and under construction. There is a general awareness of the problems in connection with nuclear power generation and strong emphasis is put on achieving highly reliable operation of nuclear power plants. Hitachi has developed a new high-reliability control system. NURECS-3000 (NUclear Power Plant High-REliability Control System), which is applied to the main control systems, such as the reactor feedwater control system, the reactor recirculation control system and the main turbine control system. The NURECS-3000 system was designed taking into account the fact that there will be failures, but the aim is for the system to continue to function correctly; it is therefore a fault-tolerant system. It has redundant components which can be completely isolated from each other in order to prevent fault propagation. The system has a hierarchical configuration, with a main controller, consisting of a triplex microcomputer system, and sub-loop controllers. Special care was taken to ensure the independence of these subsystems. Since most of the redundant system failures are caused by common-mode failures and the reliability of redundant systems depends on the reliability of the common-mode parts, the aim was to minimize these parts. (author)

Transparent reliability model for fault-tolerant safety systems

International Nuclear Information System (INIS)

Bodsberg, Lars; Hokstad, Per

1997-01-01

A reliability model is presented which may serve as a tool for identification of cost-effective configurations and operating philosophies of computer-based process safety systems. The main merit of the model is the explicit relationship in the mathematical formulas between failure cause and the means used to improve system reliability such as self-test, redundancy, preventive maintenance and corrective maintenance. A component failure taxonomy has been developed which allows the analyst to treat hardware failures, human failures, and software failures of automatic systems in an integrated manner. Furthermore, the taxonomy distinguishes between failures due to excessive environmental stresses and failures initiated by humans during engineering and operation. Attention has been given to develop a transparent model which provides predictions which are in good agreement with observed system performance, and which is applicable for non-experts in the field of reliability

Evaluation of Information Requirements of Reliability Methods in Engineering Design

DEFF Research Database (Denmark)

Marini, Vinicius Kaster; Restrepo-Giraldo, John Dairo; Ahmed-Kristensen, Saeema

2010-01-01

This paper aims to characterize the information needed to perform methods for robustness and reliability, and verify their applicability to early design stages. Several methods were evaluated on their support to synthesis in engineering design. Of those methods, FMEA, FTA and HAZOP were selected...

Some aspects of the interaction between systems- and structural reliability

International Nuclear Information System (INIS)

Schueller, G.K.; Schmitt, W.

1979-01-01

The purpose of this paper is to study the interaction between systems- and structural reliability analysis with reference to the design of structural components of LWR. Presently the evaluation of systems reliability is carried out apart from structural reliability analysis. Moreover, two basically different methodologies are used for analysis. While in systems analysis the simplified binary approach is still generally accepted, in structural reliability one has to resort to more sophisticated procedures to obtain realistic results. The interactive effect may be illustrated as follows: For example, the integrity of the primary circuit interacts with the integrity of the containment structure. This means that the probability of occurrence of the pipe rupture which may cause a LOCA and consequently leads to a build-up of temperature and pressure within the containment affects directly its structural reliability. The piping system, particularly the primary piping, in turn interacts with the protective system, which is part of the safety system. This piping structure is also subjected to various operational loading conditions. In a numerical example dealing with leakage probabilities of pipes it is shown how methods of structural reliability may be used to gain more insight in the estimation of failure rates of system components. (orig.)

Features of applying systems approach for evaluating the reliability of cryogenic systems for special purposes

Directory of Open Access Journals (Sweden)

E. D. Chertov

2016-01-01

Full Text Available Summary. The analysis of cryogenic installations confirms objective regularity of increase in amount of the tasks solved by systems of a special purpose. One of the most important directions of development of a cryogenics is creation of installations for air separation product receipt, namely oxygen and nitrogen. Modern aviation complexes require use of these gases in large numbers as in gaseous, and in the liquid state. The onboard gas systems applied in aircraft of the Russian Federation are subdivided on: oxygen system; air (nitric system; system of neutral gas; fire-proof system. Technological schemes ADI are in many respects determined by pressure of compressed air or, in a general sense, a refrigerating cycle. For the majority ADI a working body of a refrigerating cycle the divided air is, that is technological and refrigerating cycles in installation are integrated. By this principle differentiate installations: low pressure; average and high pressure; with detander; with preliminary chilling. There is also insignificant number of the ADI types in which refrigerating and technological cycles are separated. These are installations with external chilling. For the solution of tasks of control of technical condition of the BRV hardware in real time and estimates of indicators of reliability it is offered to use multi-agent technologies. Multi-agent approach is the most acceptable for creation of SPPR for reliability assessment as allows: to redistribute processing of information on elements of system that leads to increase in overall performance; to solve a problem of accumulating, storage and recycling of knowledge that will allow to increase significantly efficiency of the solution of tasks of an assessment of reliability; to considerably reduce intervention of the person in process of functioning of system that will save time of the person of the making decision (PMD and will not demand from it special skills of work with it.

Dynamic reliability of digital-based transmitters

Energy Technology Data Exchange (ETDEWEB)

Brissaud, Florent, E-mail: florent.brissaud.2007@utt.f [Institut National de l' Environnement Industriel et des Risques (INERIS), Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France) and Universite de Technologie de Troyes - UTT, Institut Charles Delaunay - ICD and UMR CNRS 6279 STMR, 12 rue Marie Curie, BP 2060, 10010 Troyes Cedex (France); Smidts, Carol [Ohio State University (OSU), Nuclear Engineering Program, Department of Mechanical Engineering, Scott Laboratory, 201 W 19th Ave, Columbus OH 43210 (United States); Barros, Anne; Berenguer, Christophe [Universite de Technologie de Troyes (UTT), Institut Charles Delaunay (ICD) and UMR CNRS 6279 STMR, 12 rue Marie Curie, BP 2060, 10010 Troyes Cedex (France)

2011-07-15

Dynamic reliability explicitly handles the interactions between the stochastic behaviour of system components and the deterministic behaviour of process variables. While dynamic reliability provides a more efficient and realistic way to perform probabilistic risk assessment than 'static' approaches, its industrial level applications are still limited. Factors contributing to this situation are the inherent complexity of the theory and the lack of a generic platform. More recently the increased use of digital-based systems has also introduced additional modelling challenges related to specific interactions between system components. Typical examples are the 'intelligent transmitters' which are able to exchange information, and to perform internal data processing and advanced functionalities. To make a contribution to solving these challenges, the mathematical framework of dynamic reliability is extended to handle the data and information which are processed and exchanged between systems components. Stochastic deviations that may affect system properties are also introduced to enhance the modelling of failures. A formalized Petri net approach is then presented to perform the corresponding reliability analyses using numerical methods. Following this formalism, a versatile model for the dynamic reliability modelling of digital-based transmitters is proposed. Finally the framework's flexibility and effectiveness is demonstrated on a substantial case study involving a simplified model of a nuclear fast reactor.

Light-water reactors reference system classification for the European reliability data system (ERDS)

International Nuclear Information System (INIS)

Melis, M.; Mancini, G.

1982-01-01

The reference system classification represents a basic stage in the organization of the European reliability data system (ERDS) for light-water reactors, a project actually in development at the Joint Research Centre, Ispra. This project is concerned with operational reliability data collection from the various ''national'' data banks, and centralization in a European reliability data system, so improving the significance of the resulting reliability evaluations. In the framework of the ERDS project, the reference system classification provides a LWR functional break-down and represents a plant-unique identification in the process of homogenization of event-data coming from the various ''national'' organizations. The report, after a brief description of the main objectives of the ERDS project, reviews the criteria followed in the elaboration of the reference system classification; then the detailed classification is presented. The nuclear power station is subdivided in about 180 systems. To each system a sheet is associated, containing: a comprehensive description of system-functions and boundaries; a descritpion of the plant operating mode, linked to the various system functions; a list of the main interface system; and finally, a list of the main components, including type and safety classification

Structural reliability of atomic power plant

International Nuclear Information System (INIS)

Klemin, A.I.; Polyakov, E.F.

1980-01-01

In 1978 the first specialized technical manual ''Technique of Calculating the Structural Reliability of an Atomic Power Plant and Its Systems in the Design Stage'' was developed. The present article contains information about the main characteristics and capabilities of the manual. The manual gives recommendations concerning the calculations of the reliability of such specific systems as the reactor control and safety system, the system of instrumentation and automatic control, and safety systems. 2 refs

Reliability modeling and analysis of smart power systems

CERN Document Server

Karki, Rajesh; Verma, Ajit Kumar

2014-01-01

The volume presents the research work in understanding, modeling and quantifying the risks associated with different ways of implementing smart grid technology in power systems in order to plan and operate a modern power system with an acceptable level of reliability. Power systems throughout the world are undergoing significant changes creating new challenges to system planning and operation in order to provide reliable and efficient use of electrical energy. The appropriate use of smart grid technology is an important drive in mitigating these problems and requires considerable research acti

Computer Model to Estimate Reliability Engineering for Air Conditioning Systems

International Nuclear Information System (INIS)

Afrah Al-Bossly, A.; El-Berry, A.; El-Berry, A.

2012-01-01

Reliability engineering is used to predict the performance and optimize design and maintenance of air conditioning systems. Air conditioning systems are expose to a number of failures. The failures of an air conditioner such as turn on, loss of air conditioner cooling capacity, reduced air conditioning output temperatures, loss of cool air supply and loss of air flow entirely can be due to a variety of problems with one or more components of an air conditioner or air conditioning system. Forecasting for system failure rates are very important for maintenance. This paper focused on the reliability of the air conditioning systems. Statistical distributions that were commonly applied in reliability settings: the standard (2 parameter) Weibull and Gamma distributions. After distributions parameters had been estimated, reliability estimations and predictions were used for evaluations. To evaluate good operating condition in a building, the reliability of the air conditioning system that supplies conditioned air to the several The company's departments. This air conditioning system is divided into two, namely the main chilled water system and the ten air handling systems that serves the ten departments. In a chilled-water system the air conditioner cools water down to 40-45 degree F (4-7 degree C). The chilled water is distributed throughout the building in a piping system and connected to air condition cooling units wherever needed. Data analysis has been done with support a computer aided reliability software, this is due to the Weibull and Gamma distributions indicated that the reliability for the systems equal to 86.012% and 77.7% respectively. A comparison between the two important families of distribution functions, namely, the Weibull and Gamma families was studied. It was found that Weibull method performed for decision making.

Reliability Analysis Study of Digital Reactor Protection System in Nuclear Power Plant

International Nuclear Information System (INIS)

Guo, Xiao Ming; Liu, Tao; Tong, Jie Juan; Zhao, Jun

2011-01-01

The Digital I and C systems are believed to improve a plants safety and reliability generally. The reliability analysis of digital I and C system has become one research hotspot. Traditional fault tree method is one of means to quantify the digital I and C system reliability. Review of advanced nuclear power plant AP1000 digital protection system evaluation makes clear both the fault tree application and analysis process to the digital system reliability. One typical digital protection system special for advanced reactor has been developed, which reliability evaluation is necessary for design demonstration. The typical digital protection system construction is introduced in the paper, and the process of FMEA and fault tree application to the digital protection system reliability evaluation are described. Reliability data and bypass logic modeling are two points giving special attention in the paper. Because the factors about time sequence and feedback not exist in reactor protection system obviously, the dynamic feature of digital system is not discussed

Software reliability and safety in nuclear reactor protection systems

Energy Technology Data Exchange (ETDEWEB)

Lawrence, J.D. [Lawrence Livermore National Lab., CA (United States)

1993-11-01

Planning the development, use and regulation of computer systems in nuclear reactor protection systems in such a way as to enhance reliability and safety is a complex issue. This report is one of a series of reports from the Computer Safety and Reliability Group, Lawrence Livermore that investigates different aspects of computer software in reactor National Laboratory, that investigates different aspects of computer software in reactor protection systems. There are two central themes in the report, First, software considerations cannot be fully understood in isolation from computer hardware and application considerations. Second, the process of engineering reliability and safety into a computer system requires activities to be carried out throughout the software life cycle. The report discusses the many activities that can be carried out during the software life cycle to improve the safety and reliability of the resulting product. The viewpoint is primarily that of the assessor, or auditor.

Software reliability and safety in nuclear reactor protection systems

International Nuclear Information System (INIS)

Lawrence, J.D.

1993-11-01

Planning the development, use and regulation of computer systems in nuclear reactor protection systems in such a way as to enhance reliability and safety is a complex issue. This report is one of a series of reports from the Computer Safety and Reliability Group, Lawrence Livermore that investigates different aspects of computer software in reactor National Laboratory, that investigates different aspects of computer software in reactor protection systems. There are two central themes in the report, First, software considerations cannot be fully understood in isolation from computer hardware and application considerations. Second, the process of engineering reliability and safety into a computer system requires activities to be carried out throughout the software life cycle. The report discusses the many activities that can be carried out during the software life cycle to improve the safety and reliability of the resulting product. The viewpoint is primarily that of the assessor, or auditor

ANALYSIS OF POWER SYSTEM RELIABILITY IMPROVEMENT FOR 74-BUS RADIAL DISTRIBUTION SYSTEM

OpenAIRE

Su Mon Myint*

2018-01-01

In Myanmar, electric power system planning is widely constructed because of more and more load growth and facing with failure of electricity, outage problems and system shut-down. Thus, not only making new power system network but also improving reliability of the existing system using suitable methods is very important to provide an adequate supply of electrical energy to its customers as economically and reliably as possible with an acceptable degree of continuity and quality that is design...

Assessing Changes in the Reliability of the U.S. Electric Power System

Energy Technology Data Exchange (ETDEWEB)

Larsen, Peter H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Stanford Univ., CA (United States). Dept. of Physics; LaCommare, Kristina H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eto, Joseph H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sweeney, James L. [Stanford Univ., CA (United States)

2015-08-01

Over the past 15 years, the most well-publicized efforts to assess trends in U.S. electric power system reliability have focused only on a subset of all power interruption events (see, for example, Amin 2008 and Campbell 2012)—namely, only the very largest events, which trigger immediate emergency reporting to federal agencies and industry regulators. Anecdotally, these events are thought by many to represent no more than 10% of the power interruptions experienced annually by electricity consumers. Moreover, a review of these emergency reports has identified shortcomings in relying on these data as reliable sources for assessing trends, even with the reliability events they report (Fisher et al. 2012). Recent work has begun to address these limitations by examining trends in reliability data collected annually by electricity distribution companies (Eto et al. 2012). In principle, all power interruptions experienced by electricity customers, regardless of size, are recorded by the distribution utility. Moreover, distribution utilities have a long history of recording this information, often in response to mandates from state public utility commissions (Eto et al. 2006). Thus, studies that rely on reliability data collected by distribution utilities can, in principle, provide a more complete basis upon which to assess trends or changes in reliability over time.

On the matter of the reliability of the chemical monitoring system based on the modern control and monitoring devices

Science.gov (United States)

Andriushin, A. V.; Dolbikova, N. S.; Kiet, S. V.; Merzlikina, E. I.; Nikitina, I. S.

2017-11-01

The reliability of the main equipment of any power station depends on the correct water chemistry. In order to provide it, it is necessary to monitor the heat carrier quality, which, in its turn, is provided by the chemical monitoring system. Thus, the monitoring system reliability plays an important part in providing reliability of the main equipment. The monitoring system reliability is determined by the reliability and structure of its hardware and software consisting of sensors, controllers, HMI and so on [1,2]. Workers of a power plant dealing with the measuring equipment must be informed promptly about any breakdowns in the monitoring system, in this case they are able to remove the fault quickly. A computer consultant system for personnel maintaining the sensors and other chemical monitoring equipment can help to notice faults quickly and identify their possible causes. Some technical solutions for such a system are considered in the present paper. The experimental results were obtained on the laboratory and experimental workbench representing a physical model of a part of the chemical monitoring system.

Approach to developing reliable space reactor power systems

International Nuclear Information System (INIS)

Mondt, J.F.; Shinbrot, C.H.

1991-01-01

The Space Reactor Power System Project is in the engineering development phase of a three-phase program. During Phase II, the Engineering Development Phase, the SP-100 Project has defined and is pursuing a new approach to developing reliable power systems. The approach to developing such a system during the early technology phase is described in this paper along with some preliminary examples to help explain the approach. Developing reliable components to meet space reactor power system requirements is based on a top down systems approach which includes a point design based on a detailed technical specification of a 100 kW power system

A hybrid approach to quantify software reliability in nuclear safety systems

International Nuclear Information System (INIS)

Arun Babu, P.; Senthil Kumar, C.; Murali, N.

2012-01-01

Highlights: ► A novel method to quantify software reliability using software verification and mutation testing in nuclear safety systems. ► Contributing factors that influence software reliability estimate. ► Approach to help regulators verify the reliability of safety critical software system during software licensing process. -- Abstract: Technological advancements have led to the use of computer based systems in safety critical applications. As computer based systems are being introduced in nuclear power plants, effective and efficient methods are needed to ensure dependability and compliance to high reliability requirements of systems important to safety. Even after several years of research, quantification of software reliability remains controversial and unresolved issue. Also, existing approaches have assumptions and limitations, which are not acceptable for safety applications. This paper proposes a theoretical approach combining software verification and mutation testing to quantify the software reliability in nuclear safety systems. The theoretical results obtained suggest that the software reliability depends on three factors: the test adequacy, the amount of software verification carried out and the reusability of verified code in the software. The proposed approach may help regulators in licensing computer based safety systems in nuclear reactors.

A physical review on power system reliability factors

International Nuclear Information System (INIS)

Navid, Taghizadegan; Ahmad Reza, Zentabchi; Mohammad Ali, Tavakoli; Nader, Samsunchi; Mohammad Ali, Tavakoli

2005-01-01

Full text : Planning and design engineers and management must necessarily take into consideration the funds available, the requirements of regulatory agencies and other restrictions that may be imposed, as well as availability of equipment and supplies. A well-designed electrical power system strikes a reasonable between reliability and cost. A prime responsibility of power system operators is to operate their systems in such a way that will provide the maximum reliability of service possible with the facilities under their control

Reliability analysis of digital based I and C system

Energy Technology Data Exchange (ETDEWEB)

Kang, I. S.; Cho, B. S.; Choi, M. J. [KOPEC, Yongin (Korea, Republic of)

1999-10-01

Rapidly, digital technology is being widely applied in replacing analog component installed in existing plant and designing new nuclear power plant for control and monitoring system in Korea as well as in foreign countries. Even though many merits of digital technology, it is being faced with a new problem of reliability assurance. The studies for solving this problem are being performed vigorously in foreign countries. The reliability of KNGR Engineered Safety Features Component Control System (ESF-CCS), digital based I and C system, was analyzed to verify fulfillment of the ALWR EPRI-URD requirement for reliability analysis and eliminate hazards in design applied new technology. The qualitative analysis using FMEA and quantitative analysis using reliability block diagram were performed. The results of analyses are shown in this paper.

78 FR 73112 - Monitoring System Conditions-Transmission Operations Reliability Standards; Interconnection...

Science.gov (United States)

2013-12-05

...\\ \\8\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, 72 FR 16416 (Apr. 4... operators and reliability coordinators to ``plan and operate the interconnected Bulk Electric System in a... mandated in the currently- effective standards, thereby improving reliability of the bulk power system...

Modelling the Replication Management in Information Systems

Directory of Open Access Journals (Sweden)

Cezar TOADER

2017-01-01

Full Text Available In the modern economy, the benefits of Web services are significant because they facilitates the activities automation in the framework of Internet distributed businesses as well as the cooperation between organizations through interconnection process running in the computer systems. This paper presents the development stages of a model for a reliable information system. This paper describes the communication between the processes within the distributed system, based on the message exchange, and also presents the problem of distributed agreement among processes. A list of objectives for the fault-tolerant systems is defined and a framework model for distributed systems is proposed. This framework makes distinction between management operations and execution operations. The proposed model promotes the use of a central process especially designed for the coordination and control of other application processes. The execution phases and the protocols for the management and the execution components are presented. This model of a reliable system could be a foundation for an entire class of distributed systems models based on the management of replication process.

Operator adaptation to changes in system reliability under adaptable automation.

Science.gov (United States)

Chavaillaz, Alain; Sauer, Juergen

2017-09-01

This experiment examined how operators coped with a change in system reliability between training and testing. Forty participants were trained for 3 h on a complex process control simulation modelling six levels of automation (LOA). In training, participants either experienced a high- (100%) or low-reliability system (50%). The impact of training experience on operator behaviour was examined during a 2.5 h testing session, in which participants either experienced a high- (100%) or low-reliability system (60%). The results showed that most operators did not often switch between LOA. Most chose an LOA that relieved them of most tasks but maintained their decision authority. Training experience did not have a strong impact on the outcome measures (e.g. performance, complacency). Low system reliability led to decreased performance and self-confidence. Furthermore, complacency was observed under high system reliability. Overall, the findings suggest benefits of adaptable automation because it accommodates different operator preferences for LOA. Practitioner Summary: The present research shows that operators can adapt to changes in system reliability between training and testing sessions. Furthermore, it provides evidence that each operator has his/her preferred automation level. Since this preference varies strongly between operators, adaptable automation seems to be suitable to accommodate these large differences.

Bayesian Reliability Estimation for Deteriorating Systems with Limited Samples Using the Maximum Entropy Approach

OpenAIRE

Xiao, Ning-Cong; Li, Yan-Feng; Wang, Zhonglai; Peng, Weiwen; Huang, Hong-Zhong

2013-01-01

In this paper the combinations of maximum entropy method and Bayesian inference for reliability assessment of deteriorating system is proposed. Due to various uncertainties, less data and incomplete information, system parameters usually cannot be determined precisely. These uncertainty parameters can be modeled by fuzzy sets theory and the Bayesian inference which have been proved to be useful for deteriorating systems under small sample sizes. The maximum entropy approach can be used to cal...

Process-aware information system development for the healthcare domain : consistency, reliability and effectiveness

NARCIS (Netherlands)

Mans, R.S.; Aalst, van der W.M.P.; Russell, N.C.; Bakker, P.J.M.; Moleman, A.J.; Rinderle-Ma, S.; Sadiq, S.; Leymann, F.

2010-01-01

Optimal support for complex healthcare processes cannot be provided by a single out-of-the-box Process-Aware Information System and necessitates the construction of customized applications based on these systems. In order to allow for the seamless integration of the new technology into the existing

Reliability analyses of safety systems for WWER-440 nuclear power plants

International Nuclear Information System (INIS)

Dusek, J.; Hojny, V.

1985-01-01

The UJV in Rez near Prague studied the reliability of the system of emergency core cooling and of the system for suppressing pressure in the sealed area of the nuclear power plant in the occurrence of a loss-of-coolant accident. The reliability of the systems was evaluated by failure tree analysis. Simulation and analytical calculation programs were developed and used for the reliability analysis. The results are briefly presented of the reliability analyses of the passive system for the immediate short-term flooding of the reactor core, of the active low-pressure system of emergency core cooling, the spray system, the bubble-vacuum system and the system of emergency supply of the steam generators. (E.S.)

National healthcare systems and the need for health information governance.

Science.gov (United States)

Hovenga, Evelyn J S

2013-01-01

This chapter gives an overview of health data, information and knowledge governance needs and associated generic principles so that information systems are able to automate such data collections from point-of-care operational systems. Also covered are health information systems' dimensions and known barriers to the delivery of quality health services, including environmental, technology and governance influences of any population's health status within the context of national health systems. This is where health information managers and health informaticians need to resolve the many challenges associated with eHealth implementations where data are assets, efficient information flow is essential, the ability to acquire new knowledge desirable, and where the use of data and information needs to be viewed from a governance perspective to ensure reliable and quality information is obtained to enhance decision making.

Recommendations for certification or measurement of reliability for reliable digital archival repositories with emphasis on access

Directory of Open Access Journals (Sweden)

Paula Regina Ventura Amorim Gonçalez

2017-04-01

Full Text Available Introduction: Considering the guidelines of ISO 16363: 2012 (Space data and information transfer systems -- Audit and certification of trustworthy digital repositories and the text of CONARQ Resolution 39 for certification of Reliable Digital Archival Repository (RDC-Arq, verify the technical recommendations should be used as the basis for a digital archival repository to be considered reliable. Objective: Identify requirements for the creation of Reliable Digital Archival Repositories with emphasis on access to information from the ISO 16363: 2012 and CONARQ Resolution 39. Methodology: For the development of the study, the methodology consisted of an exploratory, descriptive and documentary theoretical investigation, since it is based on ISO 16363: 2012 and CONARQ Resolution 39. From the perspective of the problem approach, the study is qualitative and quantitative, since the data were collected, tabulated, and analyzed from the interpretation of their contents. Results: We presented a set of Checklist Recommendations for reliability measurement and/or certification for RDC-Arq with a clipping focused on the identification of requirements with emphasis on access to information is presented. Conclusions: The right to information as well as access to reliable information is a premise for Digital Archival Repositories, so the set of recommendations is directed to archivists who work in Digital Repositories and wish to verify the requirements necessary to evaluate the reliability of the Digital Repository or still guide the information professional in collecting requirements for repository reliability certification.

An artificial intelligence system for reliability studies

International Nuclear Information System (INIS)

Llory, M.; Ancelin, C.; Bannelier, M.; Bouhadana, H.; Bouissou, M.; Lucas, J.Y.; Magne, L.; Villate, N.

1990-01-01

The EDF (French Electricity Company) software developed for computer aided reliability studies is considered. Such software tools were applied in the study of the safety requirements of the Paluel nuclear power plant. The reliability models, based on IF-THEN type rules, and the generation of models by the expert system are described. The models are then processed applying algorithm structures [fr

Methods of Estimation the Reliability and Increasing the Informativeness of the Laboratory Results (Analysis of the Laboratory Case of Measurement the Indicators of Thyroid Function

Directory of Open Access Journals (Sweden)

N A Kovyazina

2014-06-01

Full Text Available The goal of the study was to demonstrate the multilevel laboratory quality management system and point at the methods of estimating the reliability and increasing the amount of information content of the laboratory results (on the example of the laboratory case. Results. The article examines the stages of laboratory quality management which has helped to estimate the reliability of the results of determining Free T3, Free T4 and TSH. The measurement results are presented by the expanded uncertainty and the evaluation of the dynamics. Conclusion. Compliance with mandatory measures for laboratory quality management system enables laboratories to obtain reliable results and calculate the parameters that are able to increase the amount of information content of laboratory tests in clinical decision making.

A System of Deception and Fraud Detection Using Reliable Linguistic Cues Including Hedging, Disfluencies, and Repeated Phrases

Science.gov (United States)

Humpherys, Sean LaMarc

2010-01-01

Given the increasing problem of fraud, crime, and national security threats, assessing credibility is a recurring research topic in Information Systems and in other disciplines. Decision support systems can help. But the success of the system depends on reliable cues that can distinguish deceptive/truthful behavior and on a proven classification…

Composite system reliability evaluation by stochastic calculation of system operation

Energy Technology Data Exchange (ETDEWEB)

Haubrick, H -J; Hinz, H -J; Landeck, E [Dept. of Power Systems and Power Economics (Germany)

1994-12-31

This report describes a new developed probabilistic approach for steady-state composite system reliability evaluation and its exemplary application to a bulk power test system. The new computer program called PHOENIX takes into consideration transmission limitations, outages of lines and power stations and, as a central element, a highly sophisticated model to the dispatcher performing remedial actions after disturbances. The kernel of the new method is a procedure for optimal power flow calculation that has been specially adapted for the use in reliability evaluations under the above mentioned conditions. (author) 11 refs., 8 figs., 1 tab.

Reliability analysis of diverse safety logic systems of fast breeder reactor

International Nuclear Information System (INIS)

Ravi Kumar, Bh.; Apte, P.R.; Srivani, L.; Ilango Sambasivan, S.; Swaminathan, P.

2006-01-01

Safety Logic for Fast Breeder Reactor (FBR) is designed to initiate safety action against Design Basis Events. Based on the outputs of various processing circuits, Safety logic system drives the control rods of the shutdown system. So, Safety Logic system is classified as safety critical system. Therefore, reliability analysis has to be performed. This paper discusses the Reliability analysis of Diverse Safety logic systems of FBRs. For this literature survey on safety critical systems, system reliability approach and standards to be followed like IEC-61508 are discussed in detail. For Programmable Logic device based systems, Hardware Description Languages (HDL) are used. So this paper also discusses the Verification and Validation for HDLs. Finally a case study for the Reliability analysis of Safety logic is discussed. (author)

Reliability analysis of the reactor protection system with fault diagnosis

International Nuclear Information System (INIS)

Lee, D.Y.; Han, J.B.; Lyou, J.

2004-01-01

The main function of a reactor protection system (RPS) is to maintain the reactor core integrity and reactor coolant system pressure boundary. The RPS consists of the 2-out-of-m redundant architecture to assure a reliable operation. The system reliability of the RPS is a very important factor for the probability safety assessment (PSA) evaluation in the nuclear field. To evaluate the system failure rate of the k-out-of-m redundant system is not so easy with the deterministic method. In this paper, the reliability analysis method using the binomial process is suggested to calculate the failure rate of the RPS system with a fault diagnosis function. The suggested method is compared with the result of the Markov process to verify the validation of the suggested method, and applied to the several kinds of RPS architectures for a comparative evaluation of the reliability. (orig.)

Asymmetric Programming: A Highly Reliable Metadata Allocation Strategy for MLC NAND Flash Memory-Based Sensor Systems

Science.gov (United States)

Huang, Min; Liu, Zhaoqing; Qiao, Liyan

2014-01-01

While the NAND flash memory is widely used as the storage medium in modern sensor systems, the aggressive shrinking of process geometry and an increase in the number of bits stored in each memory cell will inevitably degrade the reliability of NAND flash memory. In particular, it's critical to enhance metadata reliability, which occupies only a small portion of the storage space, but maintains the critical information of the file system and the address translations of the storage system. Metadata damage will cause the system to crash or a large amount of data to be lost. This paper presents Asymmetric Programming, a highly reliable metadata allocation strategy for MLC NAND flash memory storage systems. Our technique exploits for the first time the property of the multi-page architecture of MLC NAND flash memory to improve the reliability of metadata. The basic idea is to keep metadata in most significant bit (MSB) pages which are more reliable than least significant bit (LSB) pages. Thus, we can achieve relatively low bit error rates for metadata. Based on this idea, we propose two strategies to optimize address mapping and garbage collection. We have implemented Asymmetric Programming on a real hardware platform. The experimental results show that Asymmetric Programming can achieve a reduction in the number of page errors of up to 99.05% with the baseline error correction scheme. PMID:25310473

Asymmetric Programming: A Highly Reliable Metadata Allocation Strategy for MLC NAND Flash Memory-Based Sensor Systems

Directory of Open Access Journals (Sweden)

Min Huang

2014-10-01

Full Text Available While the NAND flash memory is widely used as the storage medium in modern sensor systems, the aggressive shrinking of process geometry and an increase in the number of bits stored in each memory cell will inevitably degrade the reliability of NAND flash memory. In particular, it’s critical to enhance metadata reliability, which occupies only a small portion of the storage space, but maintains the critical information of the file system and the address translations of the storage system. Metadata damage will cause the system to crash or a large amount of data to be lost. This paper presents Asymmetric Programming, a highly reliable metadata allocation strategy for MLC NAND flash memory storage systems. Our technique exploits for the first time the property of the multi-page architecture of MLC NAND flash memory to improve the reliability of metadata. The basic idea is to keep metadata in most significant bit (MSB pages which are more reliable than least significant bit (LSB pages. Thus, we can achieve relatively low bit error rates for metadata. Based on this idea, we propose two strategies to optimize address mapping and garbage collection. We have implemented Asymmetric Programming on a real hardware platform. The experimental results show that Asymmetric Programming can achieve a reduction in the number of page errors of up to 99.05% with the baseline error correction scheme.

Reliability and Validity of the Clinical Dementia Rating for Community-Living Elderly Subjects without an Informant.

Science.gov (United States)

Nyunt, Ma Shwe Zin; Chong, Mei Sian; Lim, Wee Shiong; Lee, Tih Shih; Yap, Philip; Ng, Tze Pin

2013-01-01

The Clinical Dementia Rating (CDR) scale is widely used to assess cognitive impairment in Alzheimer's disease. It requires collateral information from a reliable informant who is not available in many instances. We adapted the original CDR scale for use with elderly subjects without an informant (CDR-NI) and evaluated its reliability and validity for assessing mild cognitive impairment (MCI) and dementia among community-dwelling elderly subjects. At two consecutive visits 1 week apart, nurses trained in CDR assessment interviewed, observed and rated cognitive and functional performance according to a protocol in 90 elderly subjects with suboptimal cognitive performance [Mini-Mental State Examination (MMSE) reliability (κ 0.77-1.00 for six domains and 0.95 for global rating) and test-retest reliability (κ 0.75-1.00 for six domains and 0.80 for global rating), good agreement (κ 0.79) with the clinical assessment status of MCI (n = 37) and dementia (n = 4) and significant differences in the mean scores for MMSE, MOCA and Instrumental Activities of Daily Living (ANOVA global p reliable assessment of MCI and dementia in community-living elderly subjects without an informant.

Fault-tolerant embedded system design and optimization considering reliability estimation uncertainty

International Nuclear Information System (INIS)

Wattanapongskorn, Naruemon; Coit, David W.

2007-01-01

In this paper, we model embedded system design and optimization, considering component redundancy and uncertainty in the component reliability estimates. The systems being studied consist of software embedded in associated hardware components. Very often, component reliability values are not known exactly. Therefore, for reliability analysis studies and system optimization, it is meaningful to consider component reliability estimates as random variables with associated estimation uncertainty. In this new research, the system design process is formulated as a multiple-objective optimization problem to maximize an estimate of system reliability, and also, to minimize the variance of the reliability estimate. The two objectives are combined by penalizing the variance for prospective solutions. The two most common fault-tolerant embedded system architectures, N-Version Programming and Recovery Block, are considered as strategies to improve system reliability by providing system redundancy. Four distinct models are presented to demonstrate the proposed optimization techniques with or without redundancy. For many design problems, multiple functionally equivalent software versions have failure correlation even if they have been independently developed. The failure correlation may result from faults in the software specification, faults from a voting algorithm, and/or related faults from any two software versions. Our approach considers this correlation in formulating practical optimization models. Genetic algorithms with a dynamic penalty function are applied in solving this optimization problem, and reasonable and interesting results are obtained and discussed

Water chemistry data acquisition, processing, evaluation and diagnostic systems in Light Water Reactors: Future improvement of plant reliability and safety

International Nuclear Information System (INIS)

Uchida, S.; Takiguchi, H.; Ishigure, K.

2006-01-01

Data acquisition, processing and evaluation systems have been applied in major Japanese PWRs and BWRs to provide (1) reliable and quick data acquisition with manpower savings in plant chemical laboratories and (2) smooth and reliable information transfer among chemists, plant operators, and supervisors. Data acquisition systems in plants consist of automatic and semi-automatic instruments for chemical analyses, e. g., X-ray fluorescence analysis and ion chromatography, while data processing systems consist of PC base-sub-systems, e.g., data storage, reliability evaluation, clear display, and document preparation for understanding the plant own water chemistry trends. Precise and reliable evaluations of water chemistry data are required in order to improve plant reliability and safety. For this, quality assurance of the water chemistry data acquisition system is needed. At the same time, theoretical models are being applied to bridge the gaps between measured water chemistry data and the information desired to understand the interaction of materials and cooling water in plants. Major models which have already been applied for plant evaluation are: (1) water radiolysis models for BWRs and PWRs; (2) crevice radiolysis model for SCC in BWRs; and (3) crevice pH model for SG tubing in PWRs. High temperature water chemistry sensors and automatic plant diagnostic systems have been applied in only restricted areas. ECP sensors are gaining popularity as tools to determine the effects of hydrogen injection in BWR systems. Automatic plant diagnostic systems based on artificial intelligence will be more popular after having sufficient experience with off line diagnostic systems. (author)

Photovoltaic performance and reliability workshop

Energy Technology Data Exchange (ETDEWEB)

Mrig, L. [ed.

1993-12-01

This workshop was the sixth in a series of workshops sponsored by NREL/DOE under the general subject of photovoltaic testing and reliability during the period 1986--1993. PV performance and PV reliability are at least as important as PV cost, if not more. In the US, PV manufacturers, DOE laboratories, electric utilities, and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in the field were brought together to exchange the technical knowledge and field experience as related to current information in this evolving field of PV reliability. The papers presented here reflect this effort since the last workshop held in September, 1992. The topics covered include: cell and module characterization, module and system testing, durability and reliability, system field experience, and standards and codes.

Reliability prediction system based on the failure rate model for electronic components

International Nuclear Information System (INIS)

Lee, Seung Woo; Lee, Hwa Ki

2008-01-01

Although many methodologies for predicting the reliability of electronic components have been developed, their reliability might be subjective according to a particular set of circumstances, and therefore it is not easy to quantify their reliability. Among the reliability prediction methods are the statistical analysis based method, the similarity analysis method based on an external failure rate database, and the method based on the physics-of-failure model. In this study, we developed a system by which the reliability of electronic components can be predicted by creating a system for the statistical analysis method of predicting reliability most easily. The failure rate models that were applied are MILHDBK- 217F N2, PRISM, and Telcordia (Bellcore), and these were compared with the general purpose system in order to validate the effectiveness of the developed system. Being able to predict the reliability of electronic components from the stage of design, the system that we have developed is expected to contribute to enhancing the reliability of electronic components

Reliability Evaluation of Service-Oriented Architecture Systems Considering Fault-Tolerance Designs

Directory of Open Access Journals (Sweden)

Kuan-Li Peng

2014-01-01

strategies. Sensitivity analysis of SOA at both coarse and fine grain levels is also studied, which can be used to efficiently identify the critical parts within the system. Two SOA system scenarios based on real industrial practices are studied. Experimental results show that the proposed SOA model can be used to accurately depict the behavior of SOA systems. Additionally, a sensitivity analysis that quantizes the effects of system structure as well as fault tolerance on the overall reliability is also studied. On the whole, the proposed reliability modeling and analysis framework may help the SOA system service provider to evaluate the overall system reliability effectively and also make smarter improvement plans by focusing resources on enhancing reliability-sensitive parts within the system.

Reliability analysis framework for computer-assisted medical decision systems

International Nuclear Information System (INIS)

Habas, Piotr A.; Zurada, Jacek M.; Elmaghraby, Adel S.; Tourassi, Georgia D.

2007-01-01

We present a technique that enhances computer-assisted decision (CAD) systems with the ability to assess the reliability of each individual decision they make. Reliability assessment is achieved by measuring the accuracy of a CAD system with known cases similar to the one in question. The proposed technique analyzes the feature space neighborhood of the query case to dynamically select an input-dependent set of known cases relevant to the query. This set is used to assess the local (query-specific) accuracy of the CAD system. The estimated local accuracy is utilized as a reliability measure of the CAD response to the query case. The underlying hypothesis of the study is that CAD decisions with higher reliability are more accurate. The above hypothesis was tested using a mammographic database of 1337 regions of interest (ROIs) with biopsy-proven ground truth (681 with masses, 656 with normal parenchyma). Three types of decision models, (i) a back-propagation neural network (BPNN), (ii) a generalized regression neural network (GRNN), and (iii) a support vector machine (SVM), were developed to detect masses based on eight morphological features automatically extracted from each ROI. The performance of all decision models was evaluated using the Receiver Operating Characteristic (ROC) analysis. The study showed that the proposed reliability measure is a strong predictor of the CAD system's case-specific accuracy. Specifically, the ROC area index for CAD predictions with high reliability was significantly better than for those with low reliability values. This result was consistent across all decision models investigated in the study. The proposed case-specific reliability analysis technique could be used to alert the CAD user when an opinion that is unlikely to be reliable is offered. The technique can be easily deployed in the clinical environment because it is applicable with a wide range of classifiers regardless of their structure and it requires neither additional

Reliability issues at the LHC

CERN Multimedia

CERN. Geneva. Audiovisual Unit; Gillies, James D

2002-01-01

The Lectures on reliability issues at the LHC will be focused on five main Modules on five days. Module 1: Basic Elements in Reliability Engineering Some basic terms, definitions and methods, from components up to the system and the plant, common cause failures and human factor issues. Module 2: Interrelations of Reliability & Safety (R&S) Reliability and risk informed approach, living models, risk monitoring. Module 3: The ideal R&S Process for Large Scale Systems From R&S goals via the implementation into the system to the proof of the compliance. Module 4: Some Applications of R&S on LHC Master logic, anatomy of risk, cause - consequence diagram, decomposition and aggregation of the system. Module 5: Lessons learned from R&S Application in various Technologies Success stories, pitfalls, constrains in data and methods, limitations per se, experienced in aviation, space, process, nuclear, offshore and transport systems and plants. The Lectures will reflect in summary the compromise in...

Making real-time reactive systems reliable

Science.gov (United States)

Marzullo, Keith; Wood, Mark

1990-01-01

A reactive system is characterized by a control program that interacts with an environment (or controlled program). The control program monitors the environment and reacts to significant events by sending commands to the environment. This structure is quite general. Not only are most embedded real time systems reactive systems, but so are monitoring and debugging systems and distributed application management systems. Since reactive systems are usually long running and may control physical equipment, fault tolerance is vital. The research tries to understand the principal issues of fault tolerance in real time reactive systems and to build tools that allow a programmer to design reliable, real time reactive systems. In order to make real time reactive systems reliable, several issues must be addressed: (1) How can a control program be built to tolerate failures of sensors and actuators. To achieve this, a methodology was developed for transforming a control program that references physical value into one that tolerates sensors that can fail and can return inaccurate values; (2) How can the real time reactive system be built to tolerate failures of the control program. Towards this goal, whether the techniques presented can be extended to real time reactive systems is investigated; and (3) How can the environment be specified in a way that is useful for writing a control program. Towards this goal, whether a system with real time constraints can be expressed as an equivalent system without such constraints is also investigated.

Automation of testing the metrological reliability of nondestructive control systems

International Nuclear Information System (INIS)

Zhukov, Yu.A.; Isakov, V.B.; Karlov, Yu.K.; Kovalevskij, Yu.A.

1987-01-01

Opportunities of microcomputers are used to solve the problem of testing control-measuring systems. Besides the main program the program of data processing when characterizing the nondestructive control systems is written in the microcomputer. The program includes two modules. The first module contains tests-programs, by which accuracy of functional elements of the microcomputer and interface elements with issuing a message to the operator on readiness of the elements for operation and failure of a certain element are determined. The second module includes: calculational programs when determining metrological reliability of measuring channel reliability, a calculational subprogram for random statistical measuring error, time instability and ''dead time''. Automation of testing metrological reliability of the nondestructive control systems increases reliability of determining metrological parameters and reduces time of system testing

A Reliability Assessment Method for the VHTR Safety Systems

International Nuclear Information System (INIS)

Lee, Hyung Sok; Jae, Moo Sung; Kim, Yong Wan

2011-01-01

The Passive safety system by very high temperature reactor which has attracted worldwide attention in the last century is the reliability safety system introduced for the improvement in the safety of the next generation nuclear power plant design. The Passive system functionality does not rely on an external source of energy, but on an intelligent use of the natural phenomena, such as gravity, conduction and radiation, which are always present. Because of these features, it is difficult to evaluate the passive safety on the risk analysis methodology having considered the existing active system failure. Therefore new reliability methodology has to be considered. In this study, the preliminary evaluation and conceptualization are tried, applying the concept of the load and capacity from the reliability physics model, designing the new passive system analysis methodology, and the trial applying to paper plant.

Optimizing the design and operation of reactor emergency systems using reliability analysis techniques

International Nuclear Information System (INIS)

Snaith, E.R.

1975-01-01

Following a reactor trip various reactor emergency systems, e.g. essential power supplies, emergency core cooling and boiler feed water arrangements are required to operate with a high degree of reliability. These systems must therefore be critically assessed to confirm their capability of operation and determine their reliability of performance. The use of probability analysis techniques enables the potential operating reliability of the systems to be calculated and this can then be compared with the overall reliability requirements. However, a system reliability analysis does much more than calculate an overall reliability value for the system. It establishes the reliability of all parts of the system and thus identifies the most sensitive areas of unreliability. This indicates the areas where any required improvements should be made and enables the overall systems' designs and modes of operation to be optimized, to meet the system and hence the overall reactor safety criteria. This paper gives specific examples of sensitive areas of unreliability that were identified as a result of a reliability analysis that was carried out on a reactor emergency core cooling system. Details are given of modifications to design and operation that were implemented with a resulting improvement in reliability of various reactor sub-systems. The report concludes that an initial calculation of system reliability should represent only the beginning of continuing process of system assessment. Data on equipment and system performance, particularly in those areas shown to be sensitive in their effect on the overall nuclear power plant reliability, should be collected and processed to give reliability data. These data should then be applied in further probabilistic analyses and the results correlated with the original analysis. This will demonstrate whether the required and the originally predicted system reliability is likely to be achieved, in the light of the actual history to date of

Reliability optimization of a redundant system with failure dependencies

Energy Technology Data Exchange (ETDEWEB)

Yu Haiyang [Institute Charles Delaunay (ICD, FRE CNRS 2848), Troyes University of Technology, Rue Marie Curie, BP 2060, 10010 Troyes (France)]. E-mail: Haiyang.YU@utt.fr; Chu Chengbin [Institute Charles Delaunay (ICD, FRE CNRS 2848), Troyes University of Technology, Rue Marie Curie, BP 2060, 10010 Troyes (France); Management School, Hefei University of Technology, 193 Tunxi Road, Hefei (China); Chatelet, Eric [Institute Charles Delaunay (ICD, FRE CNRS 2848), Troyes University of Technology, Rue Marie Curie, BP 2060, 10010 Troyes (France); Yalaoui, Farouk [Institute Charles Delaunay (ICD, FRE CNRS 2848), Troyes University of Technology, Rue Marie Curie, BP 2060, 10010 Troyes (France)

2007-12-15

In a multi-component system, the failure of one component can reduce the system reliability in two aspects: loss of the reliability contribution of this failed component, and the reconfiguration of the system, e.g., the redistribution of the system loading. The system reconfiguration can be triggered by the component failures as well as by adding redundancies. Hence, dependency is essential for the design of a multi-component system. In this paper, we study the design of a redundant system with the consideration of a specific kind of failure dependency, i.e., the redundant dependency. The dependence function is introduced to quantify the redundant dependency. With the dependence function, the redundant dependencies are further classified as independence, weak, linear, and strong dependencies. In addition, this classification is useful in that it facilitates the optimization resolution of the system design. Finally, an example is presented to illustrate the concept of redundant dependency and its application in system design. This paper thus conveys the significance of failure dependencies in the reliability optimization of systems.

Reliability optimization of a redundant system with failure dependencies

International Nuclear Information System (INIS)

Yu Haiyang; Chu Chengbin; Chatelet, Eric; Yalaoui, Farouk

2007-01-01

In a multi-component system, the failure of one component can reduce the system reliability in two aspects: loss of the reliability contribution of this failed component, and the reconfiguration of the system, e.g., the redistribution of the system loading. The system reconfiguration can be triggered by the component failures as well as by adding redundancies. Hence, dependency is essential for the design of a multi-component system. In this paper, we study the design of a redundant system with the consideration of a specific kind of failure dependency, i.e., the redundant dependency. The dependence function is introduced to quantify the redundant dependency. With the dependence function, the redundant dependencies are further classified as independence, weak, linear, and strong dependencies. In addition, this classification is useful in that it facilitates the optimization resolution of the system design. Finally, an example is presented to illustrate the concept of redundant dependency and its application in system design. This paper thus conveys the significance of failure dependencies in the reliability optimization of systems

Evaluating Proposed Investments in Power System Reliability and Resilience: Preliminary Results from Interviews with Public Utility Commission Staff

Energy Technology Data Exchange (ETDEWEB)

LaCommare, Kristina [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Larsen, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eto, Joseph [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2017-01-01

Policymakers and regulatory agencies are expressing renewed interest in the reliability and resilience of the U.S. electric power system in large part due to growing recognition of the challenges posed by climate change, extreme weather events, and other emerging threats. Unfortunately, there has been little or no consolidated information in the public domain describing how public utility/service commission (PUC) staff evaluate the economics of proposed investments in the resilience of the power system. Having more consolidated information would give policymakers a better understanding of how different state regulatory entities across the U.S. make economic decisions pertaining to reliability/resiliency. To help address this, Lawrence Berkeley National Laboratory (LBNL) was tasked by the U.S. Department of Energy Office of Energy Policy and Systems Analysis (EPSA) to conduct an initial set of interviews with PUC staff to learn more about how proposed utility investments in reliability/resilience are being evaluated from an economics perspective. LBNL conducted structured interviews in late May-early June 2016 with staff from the following PUCs: Washington D.C. (DCPSC), Florida (FPSC), and California (CPUC).

Minimal information: an urgent need to assess the functional reliability of recombinant proteins used in biological experiments

Directory of Open Access Journals (Sweden)

de Marco Ario

2008-07-01

Full Text Available Abstract Structural characterization of proteins used in biological experiments is largely neglected. In most publications, the information available is totally insufficient to judge the functionality of the proteins used and, therefore, the significance of identified protein-protein interactions (was the interaction specific or due to unspecific binding of misfolded protein regions? or reliability of kinetic and thermodynamic data (how much protein was in its native form?. As a consequence, the results of single experiments might not only become questionable, but the whole reliability of systems biology, built on these fundaments, would be weakened. The introduction of Minimal Information concerning purified proteins to add as metadata to the main body of a manuscript would render straightforward the assessment of their functional and structural qualities and, consequently, of results obtained using these proteins. Furthermore, accepted standards for protein annotation would simplify data comparison and exchange. This article has been envisaged as a proposal for aggregating scientists who share the opinion that the scientific community needs a platform for Minimum Information for Protein Functionality Evaluation (MIPFE.