Sample records for reliability analysis based

  1. Structural reliability analysis and reliability-based design optimization: Recent advances

    Qiu, ZhiPing; Huang, Ren; Wang, XiaoJun; Qi, WuChao


    We review recent research activities on structural reliability analysis, reliability-based design optimization (RBDO) and applications in complex engineering structural design. Several novel uncertainty propagation methods and reliability models, which are the basis of the reliability assessment, are given. In addition, recent developments on reliability evaluation and sensitivity analysis are highlighted as well as implementation strategies for RBDO.

  2. Reliability Distribution of Numerical Control Lathe Based on Correlation Analysis

    Xiaoyan Qi; Guixiang Shen; Yingzhi Zhang; Shuguang Sun; Bingkun Chen


    Combined Reliability distribution with correlation analysis, a new method has been proposed to make Reliability distribution where considering the elements about structure correlation and failure correlation of subsystems. Firstly, we make a sequence for subsystems by means of TOPSIS which comprehends the considerations of Reliability allocation, and introducing a Copula connecting function to set up a distribution model based on structure correlation, failure correlation and target correlation, and then acquiring reliability target area of all subsystems by Matlab. In this method, not only the traditional distribution considerations are concerned, but also correlation influences are involved, to achieve supplementing information and optimizing distribution.

  3. Reliability-Based Robustness Analysis for a Croatian Sports Hall

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


    . A complex timber structure with a large number of failure modes is modelled with only a few dominant failure modes. First, a component based robustness analysis is performed based on the reliability indices of the remaining elements after the removal of selected critical elements. The robustness...

  4. Reliability-Based Robustness Analysis for a Croatian Sports Hall

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


    This paper presents a probabilistic approach for structural robustness assessment for a timber structure built a few years ago. The robustness analysis is based on a structural reliability based framework for robustness and a simplified mechanical system modelling of a timber truss system. A comp...

  5. Reliability sensitivity-based correlation coefficient calculation in structural reliability analysis

    Yang, Zhou; Zhang, Yimin; Zhang, Xufang; Huang, Xianzhen


    The correlation coefficients of random variables of mechanical structures are generally chosen with experience or even ignored, which cannot actually reflect the effects of parameter uncertainties on reliability. To discuss the selection problem of the correlation coefficients from the reliability-based sensitivity point of view, the theory principle of the problem is established based on the results of the reliability sensitivity, and the criterion of correlation among random variables is shown. The values of the correlation coefficients are obtained according to the proposed principle and the reliability sensitivity problem is discussed. Numerical studies have shown the following results: (1) If the sensitivity value of correlation coefficient ρ is less than (at what magnitude 0.000 01), then the correlation could be ignored, which could simplify the procedure without introducing additional error. (2) However, as the difference between ρ s, that is the most sensitive to the reliability, and ρ R , that is with the smallest reliability, is less than 0.001, ρ s is suggested to model the dependency of random variables. This could ensure the robust quality of system without the loss of safety requirement. (3) In the case of | E abs|>0.001 and also | E rel|>0.001, ρ R should be employed to quantify the correlation among random variables in order to ensure the accuracy of reliability analysis. Application of the proposed approach could provide a practical routine for mechanical design and manufactory to study the reliability and reliability-based sensitivity of basic design variables in mechanical reliability analysis and design.

  6. Reliability analysis of cluster-based ad-hoc networks

    Cook, Jason L. [Quality Engineering and System Assurance, Armament Research Development Engineering Center, Picatinny Arsenal, NJ (United States); Ramirez-Marquez, Jose Emmanuel [School of Systems and Enterprises, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030 (United States)], E-mail:


    The mobile ad-hoc wireless network (MAWN) is a new and emerging network scheme that is being employed in a variety of applications. The MAWN varies from traditional networks because it is a self-forming and dynamic network. The MAWN is free of infrastructure and, as such, only the mobile nodes comprise the network. Pairs of nodes communicate either directly or through other nodes. To do so, each node acts, in turn, as a source, destination, and relay of messages. The virtue of a MAWN is the flexibility this provides; however, the challenge for reliability analyses is also brought about by this unique feature. The variability and volatility of the MAWN configuration makes typical reliability methods (e.g. reliability block diagram) inappropriate because no single structure or configuration represents all manifestations of a MAWN. For this reason, new methods are being developed to analyze the reliability of this new networking technology. New published methods adapt to this feature by treating the configuration probabilistically or by inclusion of embedded mobility models. This paper joins both methods together and expands upon these works by modifying the problem formulation to address the reliability analysis of a cluster-based MAWN. The cluster-based MAWN is deployed in applications with constraints on networking resources such as bandwidth and energy. This paper presents the problem's formulation, a discussion of applicable reliability metrics for the MAWN, and illustration of a Monte Carlo simulation method through the analysis of several example networks.




    Full Text Available The introduction of pervasive devices and mobile devices has led to immense growth of real time distributed processing. In such context reliability of the computing environment is very important. Reliability is the probability that the devices, links, processes, programs and files work efficiently for the specified period of time and in the specified condition. Distributed systems are available as conventional ring networks, clusters and agent based systems. Reliability of such systems is focused. These networks are heterogeneous and scalable in nature. There are several factors, which are to be considered for reliability estimation. These include the application related factors like algorithms, data-set sizes, memory usage pattern, input-output, communication patterns, task granularity and load-balancing. It also includes the hardware related factors like processor architecture, memory hierarchy, input-output configuration and network. The software related factors concerning reliability are operating systems, compiler, communication protocols, libraries and preprocessor performance. In estimating the reliability of a system, the performance estimation is an important aspect. Reliability analysis is approached using probability.

  8. Reliability analysis method for slope stability based on sample weight

    Zhi-gang YANG


    Full Text Available The single safety factor criteria for slope stability evaluation, derived from the rigid limit equilibrium method or finite element method (FEM, may not include some important information, especially for steep slopes with complex geological conditions. This paper presents a new reliability method that uses sample weight analysis. Based on the distribution characteristics of random variables, the minimal sample size of every random variable is extracted according to a small sample t-distribution under a certain expected value, and the weight coefficient of each extracted sample is considered to be its contribution to the random variables. Then, the weight coefficients of the random sample combinations are determined using the Bayes formula, and different sample combinations are taken as the input for slope stability analysis. According to one-to-one mapping between the input sample combination and the output safety coefficient, the reliability index of slope stability can be obtained with the multiplication principle. Slope stability analysis of the left bank of the Baihetan Project is used as an example, and the analysis results show that the present method is reasonable and practicable for the reliability analysis of steep slopes with complex geological conditions.

  9. Reliability analysis for new technology-based transmitters

    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); Universite de Technologie de Troyes (UTT), Institut Charles Delaunay (ICD) and STMR UMR CNRS 6279, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France); Barros, Anne; Berenguer, Christophe [Universite de Technologie de Troyes (UTT), Institut Charles Delaunay (ICD) and STMR UMR CNRS 6279, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France); Charpentier, Dominique [Institut National de l' Environnement Industriel et des Risques (INERIS), Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France)


    The reliability analysis of new technology-based transmitters has to deal with specific issues: various interactions between both material elements and functions, undefined behaviours under faulty conditions, several transmitted data, and little reliability feedback. To handle these particularities, a '3-step' model is proposed, based on goal tree-success tree (GTST) approaches to represent both the functional and material aspects, and includes the faults and failures as a third part for supporting reliability analyses. The behavioural aspects are provided by relationship matrices, also denoted master logic diagrams (MLD), with stochastic values which represent direct relationships between system elements. Relationship analyses are then proposed to assess the effect of any fault or failure on any material element or function. Taking these relationships into account, the probabilities of malfunction and failure modes are evaluated according to time. Furthermore, uncertainty analyses tend to show that even if the input data and system behaviour are not well known, these previous results can be obtained in a relatively precise way. An illustration is provided by a case study on an infrared gas transmitter. These properties make the proposed model and corresponding reliability analyses especially suitable for intelligent transmitters (or 'smart sensors').

  10. Reliability analysis based on the losses from failures.

    Todinov, M T


    The conventional reliability analysis is based on the premise that increasing the reliability of a system will decrease the losses from failures. On the basis of counterexamples, it is demonstrated that this is valid only if all failures are associated with the same losses. In case of failures associated with different losses, a system with larger reliability is not necessarily characterized by smaller losses from failures. Consequently, a theoretical framework and models are proposed for a reliability analysis, linking reliability and the losses from failures. Equations related to the distributions of the potential losses from failure have been derived. It is argued that the classical risk equation only estimates the average value of the potential losses from failure and does not provide insight into the variability associated with the potential losses. Equations have also been derived for determining the potential and the expected losses from failures for nonrepairable and repairable systems with components arranged in series, with arbitrary life distributions. The equations are also valid for systems/components with multiple mutually exclusive failure modes. The expected losses given failure is a linear combination of the expected losses from failure associated with the separate failure modes scaled by the conditional probabilities with which the failure modes initiate failure. On this basis, an efficient method for simplifying complex reliability block diagrams has been developed. Branches of components arranged in series whose failures are mutually exclusive can be reduced to single components with equivalent hazard rate, downtime, and expected costs associated with intervention and repair. A model for estimating the expected losses from early-life failures has also been developed. For a specified time interval, the expected losses from early-life failures are a sum of the products of the expected number of failures in the specified time intervals covering the

  11. A Research Roadmap for Computation-Based Human Reliability Analysis

    Boring, Ronald [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Joe, Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Groth, Katrina [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    The United States (U.S.) Department of Energy (DOE) is sponsoring research through the Light Water Reactor Sustainability (LWRS) program to extend the life of the currently operating fleet of commercial nuclear power plants. The Risk Informed Safety Margin Characterization (RISMC) research pathway within LWRS looks at ways to maintain and improve the safety margins of these plants. The RISMC pathway includes significant developments in the area of thermalhydraulics code modeling and the development of tools to facilitate dynamic probabilistic risk assessment (PRA). PRA is primarily concerned with the risk of hardware systems at the plant; yet, hardware reliability is often secondary in overall risk significance to human errors that can trigger or compound undesirable events at the plant. This report highlights ongoing efforts to develop a computation-based approach to human reliability analysis (HRA). This computation-based approach differs from existing static and dynamic HRA approaches in that it: (i) interfaces with a dynamic computation engine that includes a full scope plant model, and (ii) interfaces with a PRA software toolset. The computation-based HRA approach presented in this report is called the Human Unimodels for Nuclear Technology to Enhance Reliability (HUNTER) and incorporates in a hybrid fashion elements of existing HRA methods to interface with new computational tools developed under the RISMC pathway. The goal of this research effort is to model human performance more accurately than existing approaches, thereby minimizing modeling uncertainty found in current plant risk models.


    Hong-Zhong Huang


    Full Text Available Engineering design under uncertainty has gained considerable attention in recent years. A great multitude of new design optimization methodologies and reliability analysis approaches are put forth with the aim of accommodating various uncertainties. Uncertainties in practical engineering applications are commonly classified into two categories, i.e., aleatory uncertainty and epistemic uncertainty. Aleatory uncertainty arises because of unpredictable variation in the performance and processes of systems, it is irreducible even adding more data or knowledge. On the other hand, epistemic uncertainty stems from lack of knowledge of the system due to limited data, measurement limitations, or simplified approximations in modeling system behavior and it can be reduced by obtaining more data or knowledge. More specifically, aleatory uncertainty is naturally represented by a statistical distribution and its associated parameters can be characterized by sufficient data. If, however, the data is limited and can be quantified in a statistical sense, epistemic uncertainty can be considered as an alternative tool in such a situation. Of the several optional treatments for epistemic uncertainty, possibility theory and evidence theory have proved to be the most computationally efficient and stable for reliability analysis and engineering design optimization. This study first attempts to provide a better understanding of uncertainty in engineering design by giving a comprehensive overview of its classifications, theories and design considerations. Then a review is conducted of general topics such as the foundations and applications of possibility theory and evidence theory. This overview includes the most recent results from theoretical research, computational developments and performance improvement of possibility theory and evidence theory with an emphasis on revealing the capability and characteristics of quantifying uncertainty from different perspectives

  13. Reliability and risk analysis data base development: an historical perspective

    Fragola, Joseph R


    Collection of empirical data and data base development for use in the prediction of the probability of future events has a long history. Dating back at least to the 17th century, safe passage events and mortality events were collected and analyzed to uncover prospective underlying classes and associated class attributes. Tabulations of these developed classes and associated attributes formed the underwriting basis for the fledgling insurance industry. Much earlier, master masons and architects used design rules of thumb to capture the experience of the ages and thereby produce structures of incredible longevity and reliability (Antona, E., Fragola, J. and Galvagni, R. Risk based decision analysis in design. Fourth SRA Europe Conference Proceedings, Rome, Italy, 18-20 October 1993). These rules served so well in producing robust designs that it was not until almost the 19th century that the analysis (Charlton, T.M., A History Of Theory Of Structures In The 19th Century, Cambridge University Press, Cambridge, UK, 1982) of masonry voussoir arches, begun by Galileo some two centuries earlier (Galilei, G. Discorsi e dimostrazioni mathematiche intorno a due nuove science, (Discourses and mathematical demonstrations concerning two new sciences, Leiden, The Netherlands, 1638), was placed on a sound scientific basis. Still, with the introduction of new materials (such as wrought iron and steel) and the lack of theoretical knowledge and computational facilities, approximate methods of structural design abounded well into the second half of the 20th century. To this day structural designers account for material variations and gaps in theoretical knowledge by employing factors of safety (Benvenuto, E., An Introduction to the History of Structural Mechanics, Part II: Vaulted Structures and Elastic Systems, Springer-Verlag, NY, 1991) or codes of practice (ASME Boiler and Pressure Vessel Code, ASME, New York) originally developed in the 19th century (Antona, E., Fragola, J. and

  14. A Most Probable Point-Based Method for Reliability Analysis, Sensitivity Analysis and Design Optimization

    Hou, Gene J.-W.; Gumbert, Clyde R.; Newman, Perry A.


    A major step in a most probable point (MPP)-based method for reliability analysis is to determine the MPP. This is usually accomplished by using an optimization search algorithm. The optimal solutions associated with the MPP provide measurements related to safety probability. This study focuses on two commonly used approximate probability integration methods; i.e., the Reliability Index Approach (RIA) and the Performance Measurement Approach (PMA). Their reliability sensitivity equations are first derived in this paper, based on the derivatives of their respective optimal solutions. Examples are then provided to demonstrate the use of these derivatives for better reliability analysis and Reliability-Based Design Optimization (RBDO).

  15. Optimization Based Efficiencies in First Order Reliability Analysis

    Peck, Jeffrey A.; Mahadevan, Sankaran


    This paper develops a method for updating the gradient vector of the limit state function in reliability analysis using Broyden's rank one updating technique. In problems that use commercial code as a black box, the gradient calculations are usually done using a finite difference approach, which becomes very expensive for large system models. The proposed method replaces the finite difference gradient calculations in a standard first order reliability method (FORM) with Broyden's Quasi-Newton technique. The resulting algorithm of Broyden updates within a FORM framework (BFORM) is used to run several example problems, and the results compared to standard FORM results. It is found that BFORM typically requires fewer functional evaluations that FORM to converge to the same answer.

  16. Simulation and Non-Simulation Based Human Reliability Analysis Approaches

    Boring, Ronald Laurids [Idaho National Lab. (INL), Idaho Falls, ID (United States); Shirley, Rachel Elizabeth [Idaho National Lab. (INL), Idaho Falls, ID (United States); Joe, Jeffrey Clark [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    Part of the U.S. Department of Energy’s Light Water Reactor Sustainability (LWRS) Program, the Risk-Informed Safety Margin Characterization (RISMC) Pathway develops approaches to estimating and managing safety margins. RISMC simulations pair deterministic plant physics models with probabilistic risk models. As human interactions are an essential element of plant risk, it is necessary to integrate human actions into the RISMC risk model. In this report, we review simulation-based and non-simulation-based human reliability assessment (HRA) methods. Chapter 2 surveys non-simulation-based HRA methods. Conventional HRA methods target static Probabilistic Risk Assessments for Level 1 events. These methods would require significant modification for use in dynamic simulation of Level 2 and Level 3 events. Chapter 3 is a review of human performance models. A variety of methods and models simulate dynamic human performance; however, most of these human performance models were developed outside the risk domain and have not been used for HRA. The exception is the ADS-IDAC model, which can be thought of as a virtual operator program. This model is resource-intensive but provides a detailed model of every operator action in a given scenario, along with models of numerous factors that can influence operator performance. Finally, Chapter 4 reviews the treatment of timing of operator actions in HRA methods. This chapter is an example of one of the critical gaps between existing HRA methods and the needs of dynamic HRA. This report summarizes the foundational information needed to develop a feasible approach to modeling human interactions in the RISMC simulations.

  17. Automated migration analysis based on cell texture: method & reliability

    Chittenden Thomas W


    Full Text Available Abstract Background In this paper, we present and validate a way to measure automatically the extent of cell migration based on automated examination of a series of digital photographs. It was designed specifically to identify the impact of Second Hand Smoke (SHS on endothelial cell migration but has broader applications. The analysis has two stages: (1 preprocessing of image texture, and (2 migration analysis. Results The output is a graphic overlay that indicates the front lines of cell migration superimposed on each original image, with automated reporting of the distance traversed vs. time. Expert preference compares to manual placement of leading edge shows complete equivalence of automated vs. manual leading edge definition for cell migration measurement. Conclusion Our method is indistinguishable from careful manual determinations of cell front lines, with the advantages of full automation, objectivity, and speed.

  18. Architecture-Based Reliability Analysis of Web Services

    Rahmani, Cobra Mariam


    In a Service Oriented Architecture (SOA), the hierarchical complexity of Web Services (WS) and their interactions with the underlying Application Server (AS) create new challenges in providing a realistic estimate of WS performance and reliability. The current approaches often treat the entire WS environment as a black-box. Thus, the sensitivity…

  19. Reliability analysis of a gravity-based foundation for wind turbines

    Vahdatirad, Mohammad Javad; Griffiths, D. V.; Andersen, Lars Vabbersgaard


    Deterministic code-based designs proposed for wind turbine foundations, are typically biased on the conservative side, and overestimate the probability of failure which can lead to higher than necessary construction cost. In this study reliability analysis of a gravity-based foundation concerning...... technique to perform the reliability analysis. The calibrated code-based design approach leads to savings of up to 20% in the concrete foundation volume, depending on the target annual reliability level. The study can form the basis for future optimization on deterministic-based designs for wind turbine...... foundations....

  20. Analysis of Syetem Reliability in Manufacturing Cell Based on Triangular Fuzzy Number

    ZHANG Caibo; HAN Botang; SUN Changsen; XU Chunjie


    Due to lacking of test-data and field-data in reliability research during the design stage of manufacturing cell system. The degree of manufacturing cell system reliability research is increased. In order to deal with the deficient data and the uncertainty occurred from analysis and judgment, the paper discussed a method for studying reliability of manufacturing cell system through the analysis of fuzzy fault tree, which was based on triangular fuzzy number. At last, calculation case indicated that it would have great significance for ascertaining reliability index, maintenance and establishing keeping strategy towards manufacturing cell system.

  1. Methodology for reliability allocation based on fault tree analysis and dualistic contrast

    TONG Lili; CAO Xuewu


    Reliability allocation is a difficult multi-objective optimization problem.This paper presents a methodology for reliability allocation that can be applied to determine the reliability characteristics of reactor systems or subsystems.The dualistic contrast,known as one of the most powerful tools for optimization problems,is applied to the reliability allocation model of a typical system in this article.And the fault tree analysis,deemed to be one of the effective methods of reliability analysis,is also adopted.Thus a failure rate allocation model based on the fault tree analysis and dualistic contrast is achieved.An application on the emergency diesel generator in the nuclear power plant is given to illustrate the proposed method.

  2. Reliability analysis and risk-based methods for planning of operation & maintenance of offshore wind turbines

    Sørensen, John Dalsgaard


    for extreme and fatigue limit states are presented. Operation & Maintenance planning often follows corrective and preventive strategies based on information from condition monitoring and structural health monitoring systems. A reliability- and riskbased approach is presented where a life-cycle approach......Reliability analysis and probabilistic models for wind turbines are considered with special focus on structural components and application for reliability-based calibration of partial safety factors. The main design load cases to be considered in design of wind turbine components are presented...... including the effects of the control system and possible faults due to failure of electrical / mechanical components. Considerations are presented on the target reliability level for wind turbine structural components. Application is shown for reliability-based calibrations of partial safety factors...

  3. Reliability of Foundation Pile Based on Settlement and a Parameter Sensitivity Analysis

    Shujun Zhang; Luo Zhong; Zhijun Xu


    Based on the uncertainty analysis to calculation model of settlement, the formula of reliability index of foundation pile is derived. Based on this formula, the influence of coefficient of variation of the calculated settlement at pile head, coefficient of variation of the permissible limit of the settlement, coefficient of variation of the measured settlement, safety coefficient, and the mean value of calculation model coefficient on reliability is analyzed. The results indicate that (1) hig...

  4. Multidisciplinary Inverse Reliability Analysis Based on Collaborative Optimization with Combination of Linear Approximations

    Xin-Jia Meng


    Full Text Available Multidisciplinary reliability is an important part of the reliability-based multidisciplinary design optimization (RBMDO. However, it usually has a considerable amount of calculation. The purpose of this paper is to improve the computational efficiency of multidisciplinary inverse reliability analysis. A multidisciplinary inverse reliability analysis method based on collaborative optimization with combination of linear approximations (CLA-CO is proposed in this paper. In the proposed method, the multidisciplinary reliability assessment problem is first transformed into a problem of most probable failure point (MPP search of inverse reliability, and then the process of searching for MPP of multidisciplinary inverse reliability is performed based on the framework of CLA-CO. This method improves the MPP searching process through two elements. One is treating the discipline analyses as the equality constraints in the subsystem optimization, and the other is using linear approximations corresponding to subsystem responses as the replacement of the consistency equality constraint in system optimization. With these two elements, the proposed method realizes the parallel analysis of each discipline, and it also has a higher computational efficiency. Additionally, there are no difficulties in applying the proposed method to problems with nonnormal distribution variables. One mathematical test problem and an electronic packaging problem are used to demonstrate the effectiveness of the proposed method.

  5. Power electronics reliability analysis.

    Smith, Mark A.; Atcitty, Stanley


    This report provides the DOE and industry with a general process for analyzing power electronics reliability. The analysis can help with understanding the main causes of failures, downtime, and cost and how to reduce them. One approach is to collect field maintenance data and use it directly to calculate reliability metrics related to each cause. Another approach is to model the functional structure of the equipment using a fault tree to derive system reliability from component reliability. Analysis of a fictitious device demonstrates the latter process. Optimization can use the resulting baseline model to decide how to improve reliability and/or lower costs. It is recommended that both electric utilities and equipment manufacturers make provisions to collect and share data in order to lay the groundwork for improving reliability into the future. Reliability analysis helps guide reliability improvements in hardware and software technology including condition monitoring and prognostics and health management.

  6. Finite State Machine Based Evaluation Model for Web Service Reliability Analysis

    M, Thirumaran; Abarna, S; P, Lakshmi


    Now-a-days they are very much considering about the changes to be done at shorter time since the reaction time needs are decreasing every moment. Business Logic Evaluation Model (BLEM) are the proposed solution targeting business logic automation and facilitating business experts to write sophisticated business rules and complex calculations without costly custom programming. BLEM is powerful enough to handle service manageability issues by analyzing and evaluating the computability and traceability and other criteria of modified business logic at run time. The web service and QOS grows expensively based on the reliability of the service. Hence the service provider of today things that reliability is the major factor and any problem in the reliability of the service should overcome then and there in order to achieve the expected level of reliability. In our paper we propose business logic evaluation model for web service reliability analysis using Finite State Machine (FSM) where FSM will be extended to analy...

  7. Analysis and Application of Mechanical System Reliability Model Based on Copula Function

    An Hai


    Full Text Available There is complicated correlations in mechanical system. By using the advantages of copula function to solve the related issues, this paper proposes the mechanical system reliability model based on copula function. And makes a detailed research for the serial and parallel mechanical system model and gets their reliability function respectively. Finally, the application research is carried out for serial mechanical system reliability model to prove its validity by example. Using Copula theory to make mechanical system reliability modeling and its expectation, studying the distribution of the random variables (marginal distribution of the mechanical product’ life and associated structure of variables separately, can reduce the difficulty of multivariate probabilistic modeling and analysis to make the modeling and analysis process more clearly.

  8. Tensile reliability analysis for gravity dam foundation surface based on FEM and response surface method

    Tong-chun LI; Dan-dan LI; Zhi-qiang WANG


    In this study,the limit state equation for tensile reliability analysis of the foundation surface of a gravity dam was established.The possible crack length was set as the action effect and allowable crack length was set as the resistance in the limit state.The nonlinear FEM was used to obtain the crack length of the foundation surface of the gravity dam,and the linear response surface method based on the orthogonal test design method was used to calculate the reliability,providing a reasonable and simple method for calculating the reliability of the serviceability limit state.The Longtan RCC gravity dam was chosen as an example.An orthogonal test,including eleven factors and two levels,was conducted,and the tensile reliability was calculated.The analysis shows that this method is reasonable.

  9. An Evidential Reasoning-Based CREAM to Human Reliability Analysis in Maritime Accident Process.

    Wu, Bing; Yan, Xinping; Wang, Yang; Soares, C Guedes


    This article proposes a modified cognitive reliability and error analysis method (CREAM) for estimating the human error probability in the maritime accident process on the basis of an evidential reasoning approach. This modified CREAM is developed to precisely quantify the linguistic variables of the common performance conditions and to overcome the problem of ignoring the uncertainty caused by incomplete information in the existing CREAM models. Moreover, this article views maritime accident development from the sequential perspective, where a scenario- and barrier-based framework is proposed to describe the maritime accident process. This evidential reasoning-based CREAM approach together with the proposed accident development framework are applied to human reliability analysis of a ship capsizing accident. It will facilitate subjective human reliability analysis in different engineering systems where uncertainty exists in practice.

  10. A Reliability-Based Analysis of Bicyclist Red-Light Running Behavior at Urban Intersections

    Mei Huan


    Full Text Available This paper describes the red-light running behavior of bicyclists at urban intersections based on reliability analysis approach. Bicyclists’ crossing behavior was collected by video recording. Four proportional hazard models by the Cox, exponential, Weibull, and Gompertz distributions were proposed to analyze the covariate effects on safety crossing reliability. The influential variables include personal characteristics, movement information, and situation factors. The results indicate that the Cox hazard model gives the best description of bicyclists’ red-light running behavior. Bicyclists’ safety crossing reliabilities decrease as their waiting times increase. There are about 15.5% of bicyclists with negligible waiting times, who are at high risk of red-light running and very low safety crossing reliabilities. The proposed reliability models can capture the covariates’ effects on bicyclists’ crossing behavior at signalized intersections. Both personal characteristics and traffic conditions have significant effects on bicyclists’ safety crossing reliability. A bicyclist is more likely to have low safety crossing reliability and high violation risk when more riders are crossing against the red light, and they wait closer to the motorized lane. These findings provide valuable insights in understanding bicyclists’ violation behavior; and their implications in assessing bicyclists’ safety crossing reliability were discussed.

  11. Tensile reliability analysis for gravity dam foundation surface based on FEM and response surface method

    Tong-chun LI; Li, Dan-Dan; Wang, Zhi-Qiang


    In the paper, the limit state equation of tensile reliability of foundation base of gravity dam is established. The possible crack length is set as action effect and the allowance crack length is set as resistance in this limit state. The nonlinear FEM is applied to obtain the crack length of foundation base of gravity dam, and linear response surface method based on the orthogonal test design method is used to calculate the reliability,which offered an reasonable and simple analysis method t...

  12. Estimating Reliability of Disturbances in Satellite Time Series Data Based on Statistical Analysis

    Zhou, Z.-G.; Tang, P.; Zhou, M.


    Normally, the status of land cover is inherently dynamic and changing continuously on temporal scale. However, disturbances or abnormal changes of land cover — caused by such as forest fire, flood, deforestation, and plant diseases — occur worldwide at unknown times and locations. Timely detection and characterization of these disturbances is of importance for land cover monitoring. Recently, many time-series-analysis methods have been developed for near real-time or online disturbance detection, using satellite image time series. However, the detection results were only labelled with "Change/ No change" by most of the present methods, while few methods focus on estimating reliability (or confidence level) of the detected disturbances in image time series. To this end, this paper propose a statistical analysis method for estimating reliability of disturbances in new available remote sensing image time series, through analysis of full temporal information laid in time series data. The method consists of three main steps. (1) Segmenting and modelling of historical time series data based on Breaks for Additive Seasonal and Trend (BFAST). (2) Forecasting and detecting disturbances in new time series data. (3) Estimating reliability of each detected disturbance using statistical analysis based on Confidence Interval (CI) and Confidence Levels (CL). The method was validated by estimating reliability of disturbance regions caused by a recent severe flooding occurred around the border of Russia and China. Results demonstrated that the method can estimate reliability of disturbances detected in satellite image with estimation error less than 5% and overall accuracy up to 90%.

  13. Reliability analysis of supporting pressure in tunnels based on three-dimensional failure mechanism

    罗卫华; 李闻韬


    Based on nonlinear failure criterion, a three-dimensional failure mechanism of the possible collapse of deep tunnel is presented with limit analysis theory. Support pressure is taken into consideration in the virtual work equation performed under the upper bound theorem. It is necessary to point out that the properties of surrounding rock mass plays a vital role in the shape of collapsing rock mass. The first order reliability method and Monte Carlo simulation method are then employed to analyze the stability of presented mechanism. Different rock parameters are considered random variables to value the corresponding reliability index with an increasing applied support pressure. The reliability indexes calculated by two methods are in good agreement. Sensitivity analysis was performed and the influence of coefficient variation of rock parameters was discussed. It is shown that the tensile strength plays a much more important role in reliability index than dimensionless parameter, and that small changes occurring in the coefficient of variation would make great influence of reliability index. Thus, significant attention should be paid to the properties of surrounding rock mass and the applied support pressure to maintain the stability of tunnel can be determined for a given reliability index.

  14. Vibration reliability analysis for aeroengine compressor blade based on support vector machine response surface method

    GAO Hai-feng; BAI Guang-chen


    To ameliorate reliability analysis efficiency for aeroengine components, such as compressor blade, support vector machine response surface method (SRSM) is proposed. SRSM integrates the advantages of support vector machine (SVM) and traditional response surface method (RSM), and utilizes experimental samples to construct a suitable response surface function (RSF) to replace the complicated and abstract finite element model. Moreover, the randomness of material parameters, structural dimension and operating condition are considered during extracting data so that the response surface function is more agreeable to the practical model. The results indicate that based on the same experimental data, SRSM has come closer than RSM reliability to approximating Monte Carlo method (MCM); while SRSM (17.296 s) needs far less running time than MCM (10958 s) and RSM (9840 s). Therefore, under the same simulation conditions, SRSM has the largest analysis efficiency, and can be considered a feasible and valid method to analyze structural reliability.

  15. Reliability Analysis of Component Software in Wireless Sensor Networks Based on Transformation of Testing Data

    Chunyan Hou


    Full Text Available We develop an approach of component software reliability analysis which includes the benefits of both time domain, and structure based approaches. This approach overcomes the deficiency of existing NHPP techniques that fall short of addressing repair, and internal system structures simultaneously. Our solution adopts a method of transformation of testing data to cover both methods, and is expected to improve reliability prediction. This paradigm allows component-based software testing process doesn’t meet the assumption of NHPP models, and accounts for software structures by the way of modeling the testing process. According to the testing model it builds the mapping relation from the testing profile to the operational profile which enables the transformation of the testing data to build the reliability dataset required by NHPP models. At last an example is evaluated to validate and show the effectiveness of this approach.

  16. Application of the Simulation Based Reliability Analysis on the LBB methodology

    Pečínka L.; Švrček M.


    Guidelines on how to demonstrate the existence of Leak Before Break (LBB) have been developed in many western countries. These guidelines, partly based on NUREG/CR-6765, define the steps that should be fulfilled to get a conservative assessment of LBB acceptability. As a complement and also to help identify the key parameters that influence the resulting leakage and failure probabilities, the application of Simulation Based Reliability Analysis is under development. The used methodology will ...

  17. Multidisciplinary System Reliability Analysis

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


    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.


    Z.-G. Zhou


    Full Text Available Normally, the status of land cover is inherently dynamic and changing continuously on temporal scale. However, disturbances or abnormal changes of land cover — caused by such as forest fire, flood, deforestation, and plant diseases — occur worldwide at unknown times and locations. Timely detection and characterization of these disturbances is of importance for land cover monitoring. Recently, many time-series-analysis methods have been developed for near real-time or online disturbance detection, using satellite image time series. However, the detection results were only labelled with “Change/ No change” by most of the present methods, while few methods focus on estimating reliability (or confidence level of the detected disturbances in image time series. To this end, this paper propose a statistical analysis method for estimating reliability of disturbances in new available remote sensing image time series, through analysis of full temporal information laid in time series data. The method consists of three main steps. (1 Segmenting and modelling of historical time series data based on Breaks for Additive Seasonal and Trend (BFAST. (2 Forecasting and detecting disturbances in new time series data. (3 Estimating reliability of each detected disturbance using statistical analysis based on Confidence Interval (CI and Confidence Levels (CL. The method was validated by estimating reliability of disturbance regions caused by a recent severe flooding occurred around the border of Russia and China. Results demonstrated that the method can estimate reliability of disturbances detected in satellite image with estimation error less than 5% and overall accuracy up to 90%.

  19. Reliability-Based Code Calibration

    Faber, M.H.; Sørensen, John Dalsgaard


    The present paper addresses fundamental concepts of reliability based code calibration. First basic principles of structural reliability theory are introduced and it is shown how the results of FORM based reliability analysis may be related to partial safety factors and characteristic values....... Thereafter the code calibration problem is presented in its principal decision theoretical form and it is discussed how acceptable levels of failure probability (or target reliabilities) may be established. Furthermore suggested values for acceptable annual failure probabilities are given for ultimate...... and serviceability limit states. Finally the paper describes the Joint Committee on Structural Safety (JCSS) recommended procedure - CodeCal - for the practical implementation of reliability based code calibration of LRFD based design codes....

  20. An Intelligent Method for Structural Reliability Analysis Based on Response Surface

    桂劲松; 刘红; 康海贵


    As water depth increases, the structural safety and reliability of a system become more and more important and challenging. Therefore, the structural reliability method must be applied in ocean engineering design such as offshore platform design. If the performance function is known in structural reliability analysis, the first-order second-moment method is often used. If the performance function could not be definitely expressed, the response surface method is always used because it has a very clear train of thought and simple programming. However, the traditional response surface method fits the response surface of quadratic polynomials where the problem of accuracy could not be solved, because the true limit state surface can be fitted well only in the area near the checking point. In this paper, an intelligent computing method based on the whole response surface is proposed, which can be used for the situation where the performance function could not be definitely expressed in structural reliability analysis. In this method, a response surface of the fuzzy neural network for the whole area should be constructed first, and then the structural reliability can be calculated by the genetic algorithm. In the proposed method, all the sample points for the training network come from the whole area, so the true limit state surface in the whole area can be fitted. Through calculational examples and comparative analysis, it can be known that the proposed method is much better than the traditional response surface method of quadratic polynomials, because, the amount of calculation of finite element analysis is largely reduced, the accuracy of calculation is improved,and the true limit state surface can be fitted very well in the whole area. So, the method proposed in this paper is suitable for engineering application.

  1. Moment Method Based on Fuzzy Reliability Sensitivity Analysis for a Degradable Structural System

    Song Jun; Lu Zhenzhou


    For a degradable structural system with fuzzy failure region, a moment method based on fuzzy reliability sensitivity algorithm is presented. According to the value assignment of porformance function, the integral region for calculating the fuzzy failure probability is first split into a series of subregions in which the membership function values of the performance function within the fuzzy failure region can be approximated by a set of constants. The fuzzy failure probability is then transformed into a sum of products oftbe random failure probabilities and the approximate constants of the membership function in the subregions. Furthermore, the fuzzy reliability sensitivity analysis is transformed into a series of random reliability sensitivity analysis, and the random reliability sensitivity can be obtained by the constructed moment method. The primary advantages of the presented method include higher efficiency for implicit performance function with low and medium dimensionality and wide applicability to multiple failure modes and nonnormal basic random variables. The limitation is that the required computation effort grows exponentially with the increase of dimensionality of the basic random vari-able; hence, it is not suitable for high dimensionality problem. Compared with the available methods, the presented one is pretty com-petitive in the case that the dimensionality is lower than 10. The presented examples are used to verify the advantages and indicate the limitations.

  2. Quasi-Monte Carlo Simulation-Based SFEM for Slope Reliability Analysis

    Yu Yuzhen; Xie Liquan; Zhang Bingyin


    Considering the stochastic spatial variation of geotechnical parameters over the slope, a Stochastic Finite Element Method (SFEM) is established based on the combination of the Shear Strength Reduction (SSR) concept and quasi-Monte Carlo simulation. The shear strength reduction FEM is superior to the slice method based on the limit equilibrium theory in many ways, so it will be more powerful to assess the reliability of global slope stability when combined with probability theory. To illustrate the performance of the proposed method, it is applied to an example of simple slope. The results of simulation show that the proposed method is effective to perform the reliability analysis of global slope stability without presupposing a potential slip surface.

  3. System Reliability Analysis: Foundations.


    performance formulas for systems subject to pre- ventive maintenance are given. V * ~, , 9 D -2 SYSTEM RELIABILITY ANALYSIS: FOUNDATIONS Richard E...reliability in this case is V P{s can communicate with the terminal t = h(p) Sp2(((((p p)p) p)p)gp) + p(l -p)(((pL p)p)(p 2 JLp)) + p(l -p)((p(p p...For undirected networks, the basic reference is A. Satyanarayana and Kevin Wood (1982). For directed networks, the basic reference is Avinash

  4. Inter-rater Reliability of Criteria-Based Content Analysis of Children's Statements of Abuse.

    Niveau, Gérard; Lacasa, Marie-Josée; Berclaz, Michel; Germond, Michèle


    The evaluation of children's statements of sexual abuse cases in forensic cases is critically important and must and reliable. Criteria-based content analysis (CBCA) is the main component of the statement validity assessment (SVA), which is the most frequently used approach in this setting. This study investigated the inter-rater reliability (IRR) of CBCA in a forensic context. Three independent raters evaluated the transcripts of 95 statements of sexual abuse. IRR was calculated for each criterion, total score, and overall evaluation. The IRR was variable for the criteria, with several being unsatisfactory. But high IRR was found for the total CBCA scores (Kendall's W=0.84) and for overall evaluation (Kendall's W=0.65). Despite some shortcomings, SVA remains a robust method to be used in the comprehensive evaluation of children's statements of sexual abuse in the forensic setting. However, the low IRR of some CBCA criteria could justify some technical improvements. © 2015 American Academy of Forensic Sciences.

  5. Copula-Based Slope Reliability Analysis Using the Failure Domain Defined by the g-Line

    Xiaoliang Xu


    Full Text Available The estimation of the cross-correlation of shear strength parameters (i.e., cohesion and internal friction angle and the subsequent determination of the probability of failure have long been challenges in slope reliability analysis. Here, a copula-based approach is proposed to calculate the probability of failure by integrating the copula-based joint probability density function (PDF on the slope failure domain delimited with the g-line. Here, copulas are used to construct the joint PDF of shear strength parameters with specific marginal distributions and correlation structure. In the paper a failure (limit state function approach is applied to investigate a system characterized by a homogeneous slope. The results show that the values obtained by using the failure function approach are similar to those calculated by means of conventional methods, such as the first-order reliability method (FORM and Monte Carlo simulations (MC. In addition, an entropy weight (EW copula is proposed to address the discrepancies of the results calculated by different copulas to avoid over- or underestimating the slope reliability.

  6. ATLAS reliability analysis

    Bartsch, R.R.


    Key elements of the 36 MJ ATLAS capacitor bank have been evaluated for individual probabilities of failure. These have been combined to estimate system reliability which is to be greater than 95% on each experimental shot. This analysis utilizes Weibull or Weibull-like distributions with increasing probability of failure with the number of shots. For transmission line insulation, a minimum thickness is obtained and for the railgaps, a method for obtaining a maintenance interval from forthcoming life tests is suggested.


    Yao Chengyu; Zhao Jingyi


    To overcome the design limitations of traditional hydraulic control system for synthetic rubber press and such faults as high fault rate, low reliability, high energy-consuming and which always led to shutting down of post-treatment product line for synthetic rubber, brand-new hydraulic system combining with PC control and two-way cartridge valves for the press is developed, whose reliability is analyzed, reliability model of the hydraulic system for the press is established by analyzing processing steps, and reliability simulation of each step and the whole system is carried out by software MATLAB, which is verified through reliability test. The fixed time test has proved not that theory analysis is sound, but the system has characteristics of reasonable design and high reliability,and can lower the required power supply and operational energy cost.

  8. Application of the Simulation Based Reliability Analysis on the LBB methodology

    Pečínka L.


    Full Text Available Guidelines on how to demonstrate the existence of Leak Before Break (LBB have been developed in many western countries. These guidelines, partly based on NUREG/CR-6765, define the steps that should be fulfilled to get a conservative assessment of LBB acceptability. As a complement and also to help identify the key parameters that influence the resulting leakage and failure probabilities, the application of Simulation Based Reliability Analysis is under development. The used methodology will be demonstrated on the assessment of through wall leakage crack stability according R6 method. R6 is a known engineering assessment procedure for the evaluation of the integrity of the flawed structure. Influence of thermal ageing and seismic event has been elaborate.

  9. Saddlepoint approximation based structural reliability analysis with non-normal random variables


    The saddlepoint approximation (SA) can directly estimate the probability distribution of linear performance function in non-normal variables space. Based on the property of SA, three SA based methods are developed for the structural system reliability analysis. The first method is SA based reliability bounds theory (RBT), in which SA is employed to estimate failure probability and equivalent normal reliability index for each failure mode firstly, and then RBT is employed to obtain the upper and the lower bounds of system failure probability. The second method is SA based Nataf approximation, in which SA is used to estimate the probability density function (PDF) and cumulative distribution function (CDF) for the approximately linearized performance function of each failure mode. After the PDF of each failure mode and the correlation coefficients among approximately linearized performance functions are estimated, Nataf distribution is employed to approximate the joint PDF of multiple structural system performance functions, and then the system failure probability can be estimated directly by numerical simulation using the joint PDF. The third method is SA based line sampling (LS). The standardization transformation is needed to eliminate the dimensions of variables firstly in this case. Then LS method can express the system failure probability as an arithmetic average of a set of failure probabilities of the linear performance functions, and the probabilities of the linear performance functions can be estimated by the SA in the non-normal variables space. By comparing basic concepts, implementations and results of illustrations, the following conclusions can be drawn: (1) The first method can only obtain the bounds of system failure probability and it is only acceptable for the linear limit state function; (2) the second method can give the estimation of system failure probability, and its error mostly results from the approximation of Nataf distribution for the

  10. Hybrid reliability model for fatigue reliability analysis of steel bridges

    曹珊珊; 雷俊卿


    A kind of hybrid reliability model is presented to solve the fatigue reliability problems of steel bridges. The cumulative damage model is one kind of the models used in fatigue reliability analysis. The parameter characteristics of the model can be described as probabilistic and interval. The two-stage hybrid reliability model is given with a theoretical foundation and a solving algorithm to solve the hybrid reliability problems. The theoretical foundation is established by the consistency relationships of interval reliability model and probability reliability model with normally distributed variables in theory. The solving process is combined with the definition of interval reliability index and the probabilistic algorithm. With the consideration of the parameter characteristics of theS−N curve, the cumulative damage model with hybrid variables is given based on the standards from different countries. Lastly, a case of steel structure in the Neville Island Bridge is analyzed to verify the applicability of the hybrid reliability model in fatigue reliability analysis based on the AASHTO.

  11. Liquefaction of Tangier soils by using physically based reliability analysis modelling

    Dubujet P.


    Full Text Available Approaches that are widely used to characterize propensity of soils to liquefaction are mainly of empirical type. The potential of liquefaction is assessed by using correlation formulas that are based on field tests such as the standard and the cone penetration tests. These correlations depend however on the site where they were derived. In order to adapt them to other sites where seismic case histories are not available, further investigation is required. In this work, a rigorous one-dimensional modelling of the soil dynamics yielding liquefaction phenomenon is considered. Field tests consisting of core sampling and cone penetration testing were performed. They provided the necessary data for numerical simulations performed by using DeepSoil software package. Using reliability analysis, the probability of liquefaction was estimated and the obtained results were used to adapt Juang method to the particular case of sandy soils located in Tangier.

  12. Reliability Analysis of Production System of Fully-Mechanized Face Based on Output Statistic

    CAI Qing-xiang; LI Nai-liang


    Production system of fully-mechanized face is a complicated system composed of human, machine and environment, meantime influenced by various random factors. Analyzing the reliability of system needs plentiful data by means of system faults statistic. Based on the viewpoint that shift output of fully-mechanized face is the result of various random factors' synthetical influence, the process of how to analyze its reliability was deduced by using probability theory, symbolic statistics theory and systematic reliability theory combined with the concrete case study in this paper. And it has been proved that this method is feasible and valuable.

  13. Reliability Based Ship Structural Design

    Dogliani, M.; Østergaard, C.; Parmentier, G.;


    with developments of models of load effects and of structural collapse adopted in reliability formulations which aim at calibrating partial safety factors for ship structural design. New probabilistic models of still-water load effects are developed both for tankers and for containerships. New results are presented......This paper deals with the development of different methods that allow the reliability-based design of ship structures to be transferred from the area of research to the systematic application in current design. It summarises the achievements of a three-year collaborative research project dealing...... structure of several tankers and containerships. The results of the reliability analysis were the basis for the definition of a target safety level which was used to asses the partial safety factors suitable for in a new design rules format to be adopted in modern ship structural design. Finally...

  14. Reliability-Based Optimization in Structural Engineering

    Enevoldsen, I.; Sørensen, John Dalsgaard


    -based optimal inspection planning and reliability-based experiment planning. It is explained how these optimization problems can be solved by application of similar techniques. The reliability estimation is limited to first order reliability methods (FORM) for both component and systems reliability evaluation......, inclusion of the finite element method as the response evaluation tool and how the size of the problem can be made practicable. Finally, the important task of model evaluation and sensitivity analysis of the optimal solution is treated including a strategy for model-making with both pre and post-analysis.......In this paper reliability-based optimization problems in structural engineering are formulated on the basis of the classical decision theory. Several formulations are presented: Reliability-based optimal design of structural systems with component or systems reliability constraints, reliability...

  15. Kuhn-Tucker optimization based reliability analysis for probabilistic finite elements

    Liu, W. K.; Besterfield, G.; Lawrence, M.; Belytschko, T.


    The fusion of probability finite element method (PFEM) and reliability analysis for fracture mechanics is considered. Reliability analysis with specific application to fracture mechanics is presented, and computational procedures are discussed. Explicit expressions for the optimization procedure with regard to fracture mechanics are given. The results show the PFEM is a very powerful tool in determining the second-moment statistics. The method can determine the probability of failure or fracture subject to randomness in load, material properties and crack length, orientation, and location.

  16. Reliability analysis of diesel engine crankshaft based on 2D stress strength interference model


    A 2D stress strength interference model (2D-SSIM) considering that the fatigue reliability of engineering structural components has close relationship to load asymmetric ratio and its variability to some extent is put forward. The principle, geometric schematic and limit state equation of this model are presented. Reliability evaluation for a kind of diesel engine crankshaft was made based on this theory, in which multi-axial loading fatigue criteria was employed. Because more important factors, i.e.stress asymmetric ratio and its variability, are considered, it theoretically can make more accurate evaluation for structural component reliability than the traditional interference model. Correspondingly, a Monte-Carlo Method simulation solution is also given. The computation suggests that this model can yield satisfactory reliability evaluation.

  17. Reduced Expanding Load Method for Simulation-Based Structural System Reliability Analysis

    远方; 宋丽娜; 方江生


    The current situation and difficulties of the structural system reliability analysis are mentioned. Then on the basis of Monte Carlo method and computer simulation, a new analysis method reduced expanding load method ( RELM ) is presented, which can be used to solve structural reliability problems effectively and conveniently. In this method, the uncertainties of loads, structural material properties and dimensions can be fully considered. If the statistic parameters of stochastic variables are known, by using this method, the probability of failure can be estimated rather accurately. In contrast with traditional approaches, RELM method gives a much better understanding of structural failure frequency and its reliability indexβ is more meaningful. To illustrate this new idea, a specific example is given.

  18. Dynamic Reliability Analysis Method of Degraded Mechanical Components Based on Process Probability Density Function of Stress

    Peng Gao


    Full Text Available It is necessary to develop dynamic reliability models when considering strength degradation of mechanical components. Instant probability density function (IPDF of stress and process probability density function (PPDF of stress, which are obtained via different statistical methods, are defined, respectively. In practical engineering, the probability density function (PDF for the usage of mechanical components is mostly PPDF, such as the PDF acquired via the rain flow counting method. For the convenience of application, IPDF is always approximated by PPDF when using the existing dynamic reliability models. However, it may cause errors in the reliability calculation due to the approximation of IPDF by PPDF. Therefore, dynamic reliability models directly based on PPDF of stress are developed in this paper. Furthermore, the proposed models can be used for reliability assessment in the case of small amount of stress process samples by employing the fuzzy set theory. In addition, the mechanical components in solar array of satellites are chosen as representative examples to illustrate the proposed models. The results show that errors are caused because of the approximation of IPDF by PPDF and the proposed models are accurate in the reliability computation.

  19. Reliability assessment of a manual-based procedure towards learning curve modeling and fmea analysis

    Gustavo Rech


    Full Text Available Separation procedures in drug Distribution Centers (DC are manual-based activities prone to failures such as shipping exchanged, expired or broken drugs to the customer. Two interventions seem as promising in improving the reliability in the separation procedure: (i selection and allocation of appropriate operators to the procedure, and (ii analysis of potential failure modes incurred by selected operators. This article integrates Learning Curves (LC and FMEA (Failure Mode and Effect Analysis aimed at reducing the occurrence of failures in the manual separation of a drug DC. LCs parameters enable generating an index to identify the recommended operators to perform the procedures. The FMEA is then applied to the separation procedure carried out by the selected operators in order to identify failure modes. It also deployed the traditional FMEA severity index into two sub-indexes related to financial issues and damage to company´s image in order to characterize failures severity. When applied to a drug DC, the proposed method significantly reduced the frequency and severity of failures in the separation procedure.

  20. The design and use of reliability data base with analysis tool

    Doorepall, J.; Cooke, R.; Paulsen, J.; Hokstadt, P.


    With the advent of sophisticated computer tools, it is possible to give a distributed population of users direct access to reliability component operational histories. This allows the user a greater freedom in defining statistical populations of components and selecting failure modes. However, the reliability data analyst`s current analytical instrumentarium is not adequate for this purpose. The terminology used in organizing and gathering reliability data is standardized, and the statistical methods used in analyzing this data are not always suitably chosen. This report attempts to establish a baseline with regard to terminology and analysis methods, to support the use of a new analysis tool. It builds on results obtained in several projects for the ESTEC and SKI on the design of reliability databases. Starting with component socket time histories, we identify a sequence of questions which should be answered prior to the employment of analytical methods. These questions concern the homogeneity and stationarity of (possible dependent) competing failure modes and the independence of competing failure modes. Statistical tests, some of them new, are proposed for answering these questions. Attention is given to issues of non-identifiability of competing risk and clustering of failure-repair events. These ideas have been implemented in an analysis tool for grazing component socket time histories, and illustrative results are presented. The appendix provides background on statistical tests and competing failure modes. (au) 4 tabs., 17 ills., 61 refs.

  1. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    Gharouni-Nik, M.; Naeimi, M.; Ahadi, S.; Alimoradi, Z.


    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute

  2. Conditional probability Markov chain simulation based reliability analysis method for nonnormal variables


    Based on fast Markov chain simulation for generating the samples distributed in failure region and saddlepoint approximation(SA) technique,an efficient reliability analysis method is presented to evaluate the small failure probability of non-linear limit state function(LSF) with non-normal variables.In the presented method,the failure probability of the non-linear LSF is transformed into a product of the failure probability of the introduced linear LSF and a feature ratio factor.The introduced linear LSF which approximately has the same maximum likelihood points as the non-linear LSF is constructed and its failure probability can be calculated by SA technique.The feature ratio factor,which can be evaluated on the basis of multiplicative rule of probability,exhibits the relation between the failure probability of the non-linear LSF and that of the linear LSF,and it can be fast computed by utilizing the Markov chain algorithm to directly simulate the samples distributed in the failure regions of the non-linear LSF and those of the linear LSF.Moreover,the expectation and variance of the failure probability estimate are derived.The results of several examples demonstrate that the presented method has wide applicability,can be easily implemented,and possesses high precision and high efficiency.

  3. Reliability based structural design

    Vrouwenvelder, A.C.W.M.


    According to ISO 2394, structures shall be designed, constructed and maintained in such a way that they are suited for their use during the design working life in an economic way. To fulfil this requirement one needs insight into the risk and reliability under expected and non-expected actions. A ke

  4. Reliability based structural design

    Vrouwenvelder, A.C.W.M.


    According to ISO 2394, structures shall be designed, constructed and maintained in such a way that they are suited for their use during the design working life in an economic way. To fulfil this requirement one needs insight into the risk and reliability under expected and non-expected actions. A ke

  5. Dependence assessment in human reliability analysis based on D numbers and AHP

    Zhou, Xinyi; Deng, Xinyang [School of Computer and Information Science, Southwest University, Chongqing 400715 (China); Deng, Yong, E-mail: [School of Computer and Information Science, Southwest University, Chongqing 400715 (China); Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Mahadevan, Sankaran [School of Engineering, Vanderbilt University, Nashville, TN 37235 (United States)


    Highlights: • D numbers and AHP are combined to implement dependence assessment in HRA. • A new tool, called D numbers, is used to deal with the uncertainty in HRA. • The proposed method can well address the fuzziness and subjectivity in linguistic assessment. • The proposed method is well applicable in dependence assessment which inherently has a linguistic assessment process. - Abstract: Since human errors always cause heavy loss especially in nuclear engineering, human reliability analysis (HRA) has attracted more and more attention. Dependence assessment plays a vital role in HRA, measuring the dependence degree of human errors. Many researches have been done while still have improvement space. In this paper, a dependence assessment model based on D numbers and analytic hierarchy process (AHP) is proposed. Firstly, identify the factors used to measure the dependence level of two human operations. Besides, in terms of the suggested dependence level, determine and quantify the anchor points for each factor. Secondly, D numbers and AHP are adopted in model. Experts evaluate the dependence level of human operations for each factor. Then, the evaluation results are presented as D numbers and fused by D number’s combination rule that can obtain the dependence probability of human operations for each factor. The weights of factors can be determined by AHP. Thirdly, based on the dependence probability for each factor and its corresponding weight, the dependence probability of two human operations and its confidence can be obtained. The proposed method can well address the fuzziness and subjectivity in linguistic assessment. The proposed method is well applicable to assess the dependence degree of human errors in HRA which inherently has a linguistic assessment process.

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

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


    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.

  7. Space Mission Human Reliability Analysis (HRA) Project

    National Aeronautics and Space Administration — The purpose of this project is to extend current ground-based Human Reliability Analysis (HRA) techniques to a long-duration, space-based tool to more effectively...

  8. Time-Variant Reliability Analysis of FPSO Hull Girder Considering Corrosion Based on Statistics

    ZHANG Dao-kun; TANG Wen-yong; ZHANG Sheng-kun


    FPSO is a kind of important exploitation platform used in ocean oil and gas industry, which has the unique character of mooring at outsea for a long time. Since it can not be inspected and maintained thoroughly at dock like other kinds of ships, the reliability of FPSO hull girder during the whole service should be focused. Based on latest corrosion database and rational corrosion model, the ultimate strength of one FPSO is calculated under the conditions of slight, moderate and severe corrosion. The results not only provide the reliability under different corrosion conditions, but also do well for further inspection and maintenance research. The results provide necessary foundation for deciding inspection intervals and maintenance measures, which has practical sense to improve the general safety level of ocean engineering.

  9. Test-Retest Reliability of an Automated Infrared-Assisted Trunk Accelerometer-Based Gait Analysis System.

    Hsu, Chia-Yu; Tsai, Yuh-Show; Yau, Cheng-Shiang; Shie, Hung-Hai; Wu, Chu-Ming


    The aim of this study was to determine the test-retest reliability of an automated infrared-assisted, trunk accelerometer-based gait analysis system for measuring gait parameters of healthy subjects in a hospital. Thirty-five participants (28 of them females; age range, 23-79 years) performed a 5-m walk twice using an accelerometer-based gait analysis system with infrared assist. Measurements of spatiotemporal gait parameters (walking speed, step length, and cadence) and trunk control (gait symmetry, gait regularity, acceleration root mean square (RMS), and acceleration root mean square ratio (RMSR)) were recorded in two separate walking tests conducted 1 week apart. Relative and absolute test-retest reliability was determined by calculating the intra-class correlation coefficient (ICC3,1) and smallest detectable difference (SDD), respectively. The test-retest reliability was excellent for walking speed (ICC = 0.87, 95% confidence interval = 0.74-0.93, SDD = 13.4%), step length (ICC = 0.81, 95% confidence interval = 0.63-0.91, SDD = 12.2%), cadence (ICC = 0.81, 95% confidence interval = 0.63-0.91, SDD = 10.8%), and trunk control (step and stride regularity in anterior-posterior direction, acceleration RMS and acceleration RMSR in medial-lateral direction, and acceleration RMS and stride regularity in vertical direction). An automated infrared-assisted, trunk accelerometer-based gait analysis system is a reliable tool for measuring gait parameters in the hospital environment.

  10. Reliability analysis on passive residual heat removal of AP1000 based on Grey model

    Qi, Shi; Zhou, Tao; Shahzad, Muhammad Ali; Li, Yu [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, Beijing (China); Jiang, Guangming [Nuclear Power Institute of China, Chengdu (China). Science and Technology on Reactor System Design Technology Laboratory


    It is common to base the design of passive systems on the natural laws of physics, such as gravity, heat conduction, inertia. For AP1000, a generation-III reactor, such systems have an inherent safety associated with them due to the simplicity of their structures. However, there is a fairly large amount of uncertainty in the operating conditions of these passive safety systems. In some cases, a small deviation in the design or operating conditions can affect the function of the system. The reliability of the passive residual heat removal is analysed.

  11. Reliability Analysis of Sensor Networks

    JIN Yan; YANG Xiao-zong; WANG Ling


    To Integrate the capacity of sensing, communication, computing, and actuating, one of the compelling technological advances of these years has been the appearance of distributed wireless sensor network (DSN) for information gathering tasks. In order to save the energy, multi-hop routing between the sensor nodes and the sink node is necessary because of limited resource. In addition, the unpredictable conditional factors make the sensor nodes unreliable. In this paper, the reliability of routing designed for sensor network and some dependability issues of DSN, such as MTTF(mean time to failure) and the probability of connectivity between the sensor nodes and the sink node are analyzed.Unfortunately, we could not obtain the accurate result for the arbitrary network topology, which is # P-hard problem.And the reliability analysis of restricted topologies clustering-based is given. The method proposed in this paper will show us a constructive idea about how to place energyconstrained sensor nodes in the network efficiently from the prospective of reliability.

  12. Reliability Analysis-Based Numerical Calculation of Metal Structure of Bridge Crane

    Wenjun Meng


    Full Text Available The study introduced a finite element model of DQ75t-28m bridge crane metal structure and made finite element static analysis to obtain the stress response of the dangerous point of metal structure in the most extreme condition. The simulated samples of the random variable and the stress of the dangerous point were successfully obtained through the orthogonal design. Then, we utilized BP neural network nonlinear mapping function trains to get the explicit expression of stress in response to the random variable. Combined with random perturbation theory and first-order second-moment (FOSM method, the study analyzed the reliability and its sensitivity of metal structure. In conclusion, we established a novel method for accurately quantitative analysis and design of bridge crane metal structure.

  13. Saddlepoint approximation based line sampling method for uncertainty propagation in fuzzy and random reliability analysis


    For structural system with random basic variables as well as fuzzy basic variables,uncertain propagation from two kinds of basic variables to the response of the structure is investigated.A novel algorithm for obtaining membership function of fuzzy reliability is presented with saddlepoint approximation(SA)based line sampling method.In the presented method,the value domain of the fuzzy basic variables under the given membership level is firstly obtained according to their membership functions.In the value domain of the fuzzy basic variables corresponding to the given membership level,bounds of reliability of the structure response satisfying safety requirement are obtained by employing the SA based line sampling method in the reduced space of the random variables.In this way the uncertainty of the basic variables is propagated to the safety measurement of the structure,and the fuzzy membership function of the reliability is obtained.Compared to the direct Monte Carlo method for propagating the uncertainties of the fuzzy and random basic variables,the presented method can considerably improve computational efficiency with acceptable precision.The presented method has wider applicability compared to the transformation method,because it doesn’t limit the distribution of the variable and the explicit expression of performance function, and no approximation is made for the performance function during the computing process.Additionally,the presented method can easily treat the performance function with cross items of the fuzzy variable and the random variable,which isn’t suitably approximated by the existing transformation methods.Several examples are provided to illustrate the advantages of the presented method.

  14. Reliability based design optimization: Formulations and methodologies

    Agarwal, Harish

    Modern products ranging from simple components to complex systems should be designed to be optimal and reliable. The challenge of modern engineering is to ensure that manufacturing costs are reduced and design cycle times are minimized while achieving requirements for performance and reliability. If the market for the product is competitive, improved quality and reliability can generate very strong competitive advantages. Simulation based design plays an important role in designing almost any kind of automotive, aerospace, and consumer products under these competitive conditions. Single discipline simulations used for analysis are being coupled together to create complex coupled simulation tools. This investigation focuses on the development of efficient and robust methodologies for reliability based design optimization in a simulation based design environment. Original contributions of this research are the development of a novel efficient and robust unilevel methodology for reliability based design optimization, the development of an innovative decoupled reliability based design optimization methodology, the application of homotopy techniques in unilevel reliability based design optimization methodology, and the development of a new framework for reliability based design optimization under epistemic uncertainty. The unilevel methodology for reliability based design optimization is shown to be mathematically equivalent to the traditional nested formulation. Numerical test problems show that the unilevel methodology can reduce computational cost by at least 50% as compared to the nested approach. The decoupled reliability based design optimization methodology is an approximate technique to obtain consistent reliable designs at lesser computational expense. Test problems show that the methodology is computationally efficient compared to the nested approach. A framework for performing reliability based design optimization under epistemic uncertainty is also developed


    姜年朝; 周光明; 张逊; 戴勇; 倪俊; 张志清


    A high cycle fatigue reliability analysis approach to helicopter rotor hub is proposed under working load spectrum .Automatic calculation for the approach is implemented through writing the calculating programs .In the system ,the modification of geometric model of rotor hub is controlled by several parameters ,and finite element method and S-N curve method are then employed to solve the fatigue life by automatically assigned parameters .A database between assigned parameters and fatigue life is obtained via Latin Hypercube Sampling (LHS) on toler-ance zone of rotor hub .Different data-fitting technologies are used and compared to determine a highest-precision approximation for this database .The parameters are assumed to be independent of each other and follow normal distributions .Fatigue reliability is then computed by the Monte Carlo (MC) method and the mean-value first order second moment (M FOSM ) method .Results show that the approach has high efficiency and precision ,and is suit-able for engineering application .

  16. A New Sampling Approach for Response Surface Method Based Reliability Analysis and Its Application

    Xin-Jia Meng


    Full Text Available A response surface method based on the all sample point interpolation approach (ASPIA is proposed to improve the efficiency of reliability computation. ASPIA obtains new sample points through linear interpolation. These new sample points are occasionally extremely dense, thus easily generating an ill-conditioned problem for approximation functions. A mobile most probable failure point strategy is used to solve this problem. The advantage of the proposed method is proven by two numerical examples. With the ASPIA, the approximated process can rapidly approach the actual limit equation with accuracy. Additionally, there are no difficulties in applying the proposed ASPIA to the response surface model with or without cross terms. Solution results for the numerical examples indicate that the use of the response surface function with cross terms increases time cost, but result accuracy cannot be improved significantly. Finally, the proposed method is successfully used to analyze the reliability of the hydraulic cylinder of a forging hydraulic press by combining MATLAB and ANSYS software. The engineering example confirms the practicality of this method.

  17. Comprehensive Reliability Allocation Method for CNC Lathes Based on Cubic Transformed Functions of Failure Mode and Effects Analysis

    YANG Zhou; ZHU Yunpeng; REN Hongrui; ZHANG Yimin


    Reliability allocation of computerized numerical controlled(CNC) lathes is very important in industry. Traditional allocation methods only focus on high-failure rate components rather than moderate failure rate components, which is not applicable in some conditions. Aiming at solving the problem of CNC lathes reliability allocating, a comprehensive reliability allocation method based on cubic transformed functions of failure modes and effects analysis(FMEA) is presented. Firstly, conventional reliability allocation methods are introduced. Then the limitations of direct combination of comprehensive allocation method with the exponential transformed FMEA method are investigated. Subsequently, a cubic transformed function is established in order to overcome these limitations. Properties of the new transformed functions are discussed by considering the failure severity and the failure occurrence. Designers can choose appropriate transform amplitudes according to their requirements. Finally, a CNC lathe and a spindle system are used as an example to verify the new allocation method. Seven criteria are considered to compare the results of the new method with traditional methods. The allocation results indicate that the new method is more flexible than traditional methods. By employing the new cubic transformed function, the method covers a wider range of problems in CNC reliability allocation without losing the advantages of traditional methods.

  18. Reliability analysis for determining performance of barrage based on gates operation

    Adiningrum, C.; Hadihardaja, I. K.


    Some rivers located on a flat slope topography such as Cilemahabang river and Ciherang river in Cilemahabang watershed, Bekasi regency, West Java are susceptible to flooding. The inundation mostly happens near a barrage in the middle and downstream of the Cilemahabang watershed, namely the Cilemahabang and Caringin barrages. Barrages or gated weirs are difficult to exploit since the gate must be kept and operated properly under any circumstances. Therefore, a reliability analysis of the gates operation is necessary to determine the performance of the barrage with respect to the number of gates opened and the gates opening heights. The First Order Second Moment (FOSM) method was used to determine the performance by the reliability index (β) and the probability of failure (risk). It was found that for Cilemahabang Barrage, the number of gates opened with load (L) represents the peak discharge derived from various rainfall (P) respectively one gate with opening height (h=1m) for Preal, two gates (h=1m and h=1,5m) for P50, and three gates (each gate with h=2,5m) for P100. For Caringin Barrage, the results are minimum three gates opened (each gate with h=2,5 m) for Preal, five gates opened (each gate with h=2,5m) for P50, and six gates opened (each gate with h=2,5m) for P100. It can be concluded that a greater load (L) needs greater resistance (R) to counterbalance. Resistance can be added by increasing the number of gates opened and the gate opening height. A higher number of gates opened will lead to the decrease of water level in the upstream of barrage and less risk of overflow.

  19. Test-Retest Reliability of an Automated Infrared-Assisted Trunk Accelerometer-Based Gait Analysis System

    Chia-Yu Hsu


    Full Text Available The aim of this study was to determine the test-retest reliability of an automated infrared-assisted, trunk accelerometer-based gait analysis system for measuring gait parameters of healthy subjects in a hospital. Thirty-five participants (28 of them females; age range, 23–79 years performed a 5-m walk twice using an accelerometer-based gait analysis system with infrared assist. Measurements of spatiotemporal gait parameters (walking speed, step length, and cadence and trunk control (gait symmetry, gait regularity, acceleration root mean square (RMS, and acceleration root mean square ratio (RMSR were recorded in two separate walking tests conducted 1 week apart. Relative and absolute test-retest reliability was determined by calculating the intra-class correlation coefficient (ICC3,1 and smallest detectable difference (SDD, respectively. The test-retest reliability was excellent for walking speed (ICC = 0.87, 95% confidence interval = 0.74–0.93, SDD = 13.4%, step length (ICC = 0.81, 95% confidence interval = 0.63–0.91, SDD = 12.2%, cadence (ICC = 0.81, 95% confidence interval = 0.63–0.91, SDD = 10.8%, and trunk control (step and stride regularity in anterior-posterior direction, acceleration RMS and acceleration RMSR in medial-lateral direction, and acceleration RMS and stride regularity in vertical direction. An automated infrared-assisted, trunk accelerometer-based gait analysis system is a reliable tool for measuring gait parameters in the hospital environment.

  20. Shock reliability analysis and improvement of MEMS electret-based vibration energy harvesters

    Renaud, M.; Fujita, T.; Goedbloed, M.; de Nooijer, C.; van Schaijk, R.


    Vibration energy harvesters can serve as a replacement solution to batteries for powering tire pressure monitoring systems (TPMS). Autonomous wireless TPMS powered by microelectromechanical system (MEMS) electret-based vibration energy harvester have been demonstrated. The mechanical reliability of the MEMS harvester still has to be assessed in order to bring the harvester to the requirements of the consumer market. It should survive the mechanical shocks occurring in the tire environment. A testing procedure to quantify the shock resilience of harvesters is described in this article. Our first generation of harvesters has a shock resilience of 400 g, which is far from being sufficient for the targeted application. In order to improve this aspect, the first important aspect is to understand the failure mechanism. Failure is found to occur in the form of fracture of the device’s springs. It results from impacts between the anchors of the springs when the harvester undergoes a shock. The shock resilience of the harvesters can be improved by redirecting these impacts to nonvital parts of the device. With this philosophy in mind, we design three types of shock absorbing structures and test their effect on the shock resilience of our MEMS harvesters. The solution leading to the best results consists of rigid silicon stoppers covered by a layer of Parylene. The shock resilience of the harvesters is brought above 2500 g. Results in the same range are also obtained with flexible silicon bumpers, which are simpler to manufacture.

  1. Reliability Analysis of Wind Turbines

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard


    In order to minimise the total expected life-cycle costs of a wind turbine it is important to estimate the reliability level for all components in the wind turbine. This paper deals with reliability analysis for the tower and blades of onshore wind turbines placed in a wind farm. The limit states...... consideres are in the ultimate limit state (ULS) extreme conditions in the standstill position and extreme conditions during operating. For wind turbines, where the magnitude of the loads is influenced by the control system, the ultimate limit state can occur in both cases. In the fatigue limit state (FLS......) the reliability level for a wind turbine placed in a wind farm is considered, and wake effects from neighbouring wind turbines is taken into account. An illustrative example with calculation of the reliability for mudline bending of the tower is considered. In the example the design is determined according...

  2. Reliability analysis in intelligent machines

    Mcinroy, John E.; Saridis, George N.


    Given an explicit task to be executed, an intelligent machine must be able to find the probability of success, or reliability, of alternative control and sensing strategies. By using concepts for information theory and reliability theory, new techniques for finding the reliability corresponding to alternative subsets of control and sensing strategies are proposed such that a desired set of specifications can be satisfied. The analysis is straightforward, provided that a set of Gaussian random state variables is available. An example problem illustrates the technique, and general reliability results are presented for visual servoing with a computed torque-control algorithm. Moreover, the example illustrates the principle of increasing precision with decreasing intelligence at the execution level of an intelligent machine.

  3. Production Facility System Reliability Analysis Report

    Dale, Crystal Buchanan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Klein, Steven Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    This document describes the reliability, maintainability, and availability (RMA) modeling of the Los Alamos National Laboratory (LANL) design for the Closed Loop Helium Cooling System (CLHCS) planned for the NorthStar accelerator-based 99Mo production facility. The current analysis incorporates a conceptual helium recovery system, beam diagnostics, and prototype control system into the reliability analysis. The results from the 1000 hr blower test are addressed.

  4. On Bayesian System Reliability Analysis

    Soerensen Ringi, M.


    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.

  5. Reliability prediction of large fuel cell stack based on structure stress analysis

    Liu, L. F.; Liu, B.; Wu, C. W.


    The aim of this paper is to improve the reliability of Proton Electrolyte Membrane Fuel Cell (PEMFC) stack by designing the clamping force and the thickness difference between the membrane electrode assembly (MEA) and the gasket. The stack reliability is directly determined by the component reliability, which is affected by the material property and contact stress. The component contact stress is a random variable because it is usually affected by many uncertain factors in the production and clamping process. We have investigated the influences of parameter variation coefficient on the probability distribution of contact stress using the equivalent stiffness model and the first-order second moment method. The optimal contact stress to make the component stay in the highest level reliability is obtained by the stress-strength interference model. To obtain the optimal contact stress between the contact components, the optimal thickness of the component and the stack clamping force are optimally designed. Finally, a detailed description is given how to design the MEA and gasket dimensions to obtain the highest stack reliability. This work can provide a valuable guidance in the design of stack structure for a high reliability of fuel cell stack.

  6. Reliability-based optimization of engineering structures

    Sørensen, John Dalsgaard


    The theoretical basis for reliability-based structural optimization within the framework of Bayesian statistical decision theory is briefly described. Reliability-based cost benefit problems are formulated and exemplitied with structural optimization. The basic reliability-based optimization prob...

  7. Design Optimization of ESD (Emergency ShutDown System for Offshore Process Based on Reliability Analysis

    Bae Jeong-hoon


    Full Text Available Hydrocarbon leaks have a major accident potential and it could give significant damages to human, property and environment.To prevent these risks from the leak in design aspects, installation of ESD system is representative. Because the ESD system should be operated properly at any time, It needs high reliability and much cost. To make ESD system with high reliability and reasonable cost, it is a need to find specific design method.In this study, we proposed the multi-objective design optimization method and performed the optimization of the ESD system for 1st separation system to satisfy high reliability and cost-effective.‘NSGA-II (Non-dominated Sorting Genetic Algorithm-II’ was applied and two objective functions of ‘Reliability’ and ‘Cost’ of system were defined. Six design variables were set to related variables for system configuration. To verify the result of the optimization, the results of existing design and optimum design were compared in aspects of reliability and cost. With the optimization method proposed from this study, it was possible to derive the reliable and economical design of the ESD system.

  8. Investigation on Thermal Contact Conductance Based on Data Analysis Method of Reliability

    WANG Zongren; YANG Jun; YANG Mingyuan; ZHANG Weifang


    The method of reliability is proposed for the investigation of thermal contact conductance (TCC) in this study.A new definition is introduced,namely reliability thermal contact conductance (RTCC),which is defined as the TCC value that meets the reliability design requirement of the structural materials under consideration.An experimental apparatus with the compensation heater to test the TCC is introduced here.A practical engineering example is utilized to demonstrate the applicability of the proposed approach.By using a statistical regression model along with experimental data obtained from the interfaces of the structural materials GH4169 and K417 used in aero-engine,the estimate values and the confidence level of TCC and RTCC values are studied and compared.The results show that the testing values of TCC increase with interface pressure and the proposed RTCC model matches the test results better at high interface pressure.

  9. Reliability analysis for aeroengine turbine disc fatigue life with multiple random variables based on distributed collaborative response surface method

    高海峰; 白广忱; 高阳; 鲍天未


    The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables, such as applied load, working temperature, geometrical dimensions and material properties. In order to ameliorate reliability analysis efficiency without loss of reliability, the distributed collaborative response surface method (DCRSM) was proposed, and its basic theories were established in this work. Considering the failure dependency among the failure modes, the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables. Then, the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion. Finally, the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method. Through the comparison of DCRSM, Monte Carlo method (MCM) and the traditional response surface method (RSM), the results show that the computational precision for DCRSM is more consistent with MCM than RSM, while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions. Thus, DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables, and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.

  10. Bayesian Reliability-Growth Analysis for Statistical of Diverse Population Based on Non-homogeneous Poisson Process

    MING Zhimao; TAO Junyong; ZHANG Yunan; YI Xiaoshan; CHEN Xun


    New armament systems are subjected to the method for dealing with multi-stage system reliability-growth statistical problems of diverse population in order to improve reliability before starting mass production. Aiming at the test process which is high expense and small sample-size in the development of complex system, the specific methods are studied on how to process the statistical information of Bayesian reliability growth regarding diverse populations. Firstly, according to the characteristics of reliability growth during product development, the Bayesian method is used to integrate the testing information of multi-stage and the order relations of distribution parameters. And then a Gamma-Beta prior distribution is proposed based on non-homogeneous Poisson process(NHPP) corresponding to the reliability growth process. The posterior distribution of reliability parameters is obtained regarding different stages of product, and the reliability parameters are evaluated based on the posterior distribution. Finally, Bayesian approach proposed in this paper for multi-stage reliability growth test is applied to the test process which is small sample-size in the astronautics filed. The results of a numerical example show that the presented model can make use of the diverse information synthetically, and pave the way for the application of the Bayesian model for multi-stage reliability growth test evaluation with small sample-size. The method is useful for evaluating multi-stage system reliability and making reliability growth plan rationally.

  11. A Reliability Accelerated Test of High-speed Punch Based on Failure Analysis

    Chen Lan


    Full Text Available By analyzing the maintainability data of a certain high-speed punch, its main fault modes, such as oil/gas parts damage, parts damage and leakages, were identified. According to the fault signal measurability and the accelerated failure mechanism, the content and scheme of a reliability accelerated test (RAT were planned specifically, which was partly verified by some tests on a high-speed punch. This paper provides a basis for the RAT of high-speed punch.

  12. Simulation and reliability analysis of shunt active power filter based on instantaneous reactive power theory

    CUI Yu-long; LIU Hong; WANG Jing-qin; SUN Shu-guang


    This paper first discusses the operating principle ofinstantaneous reactive power theory. Then, the theory is introduced into shunt active power filter and its control scheme is studied. Finally, Matlab/Simulink power system toolbox is used to simulate the system. In the simulation model, as the most common harmonic source, 3-phase thyfistor bridge rectifier circuit is constructed.The simulation results before and after the shunt active filter was switched to the system corresponding to different firing angles of the thyristors are presented and analyzed, which demonstrate the practicability and reliability of the proposed shunt active filter scheme.

  13. Time-Dependent Reliability Modeling and Analysis Method for Mechanics Based on Convex Process

    Lei Wang


    Full Text Available The objective of the present study is to evaluate the time-dependent reliability for dynamic mechanics with insufficient time-varying uncertainty information. In this paper, the nonprobabilistic convex process model, which contains autocorrelation and cross-correlation, is firstly employed for the quantitative assessment of the time-variant uncertainty in structural performance characteristics. By combination of the set-theory method and the regularization treatment, the time-varying properties of structural limit state are determined and a standard convex process with autocorrelation for describing the limit state is formulated. By virtue of the classical first-passage method in random process theory, a new nonprobabilistic measure index of time-dependent reliability is proposed and its solution strategy is mathematically conducted. Furthermore, the Monte-Carlo simulation method is also discussed to illustrate the feasibility and accuracy of the developed approach. Three engineering cases clearly demonstrate that the proposed method may provide a reasonable and more efficient way to estimate structural safety than Monte-Carlo simulations throughout a product life-cycle.

  14. Reliability-based concurrent subspace optimization method

    FAN Hui; LI Wei-ji


    To avoid the high computational cost and much modification in the process of applying traditional re-liability-based design optimization method, a new reliability-based concurrent subspace optimization approach is proposed based on the comparison and analysis of the existing muhidisciplinary optimization techniques and reli-ability assessment methods. It is shown through a canard configuration optimization for a three-surface transport that the proposed method is computationally efficient and practical with the least modification to the current de-terministic optimization process.

  15. Sensitivity Analysis of Component Reliability



    In a system, Every component has its unique position within system and its unique failure characteristics. When a component's reliability is changed, its effect on system reliability is not equal. Component reliability sensitivity is a measure of effect on system reliability while a component's reliability is changed. In this paper, the definition and relative matrix of component reliability sensitivity is proposed, and some of their characteristics are analyzed. All these will help us to analyse or improve the system reliability.

  16. A Multi-Criteria Decision Analysis based methodology for quantitatively scoring the reliability and relevance of ecotoxicological data.

    Isigonis, Panagiotis; Ciffroy, Philippe; Zabeo, Alex; Semenzin, Elena; Critto, Andrea; Giove, Silvio; Marcomini, Antonio


    Ecotoxicological data are highly important for risk assessment processes and are used for deriving environmental quality criteria, which are enacted for assuring the good quality of waters, soils or sediments and achieving desirable environmental quality objectives. Therefore, it is of significant importance the evaluation of the reliability of available data for analysing their possible use in the aforementioned processes. The thorough analysis of currently available frameworks for the assessment of ecotoxicological data has led to the identification of significant flaws but at the same time various opportunities for improvement. In this context, a new methodology, based on Multi-Criteria Decision Analysis (MCDA) techniques, has been developed with the aim of analysing the reliability and relevance of ecotoxicological data (which are produced through laboratory biotests for individual effects), in a transparent quantitative way, through the use of expert knowledge, multiple criteria and fuzzy logic. The proposed methodology can be used for the production of weighted Species Sensitivity Weighted Distributions (SSWD), as a component of the ecological risk assessment of chemicals in aquatic systems. The MCDA aggregation methodology is described in detail and demonstrated through examples in the article and the hierarchically structured framework that is used for the evaluation and classification of ecotoxicological data is shortly discussed. The methodology is demonstrated for the aquatic compartment but it can be easily tailored to other environmental compartments (soil, air, sediments).



    An efficient importance sampling algorithm is presented to analyze reliability of complex structural system with multiple failure modes and fuzzy-random uncertainties in basic variables and failure modes. In order to improve the sampling efficiency, the simulated annealing algorithm is adopted to optimize the density center of the importance sampling for each failure mode, and results that the more significant contribution the points make to fuzzy failure probability, the higher occurrence possibility the points are sampled. For the system with multiple fuzzy failure modes, a weighted and mixed importance sampling function is constructed. The contribution of each fuzzy failure mode to the system failure probability is represented by the appropriate factors, and the efficiency of sampling is improved furthermore. The variances and the coefficients of variation are derived for the failure probability estimations. Two examples are introduced to illustrate the rationality of the present method. Comparing with the direct Monte-Carlo method, the improved efficiency and the precision of the method are verified by the examples.

  18. Reliability Analysis of a Steel Frame

    M. Sýkora


    Full Text Available A steel frame with haunches is designed according to Eurocodes. The frame is exposed to self-weight, snow, and wind actions. Lateral-torsional buckling appears to represent the most critical criterion, which is considered as a basis for the limit state function. In the reliability analysis, the probabilistic models proposed by the Joint Committee for Structural Safety (JCSS are used for basic variables. The uncertainty model coefficients take into account the inaccuracy of the resistance model for the haunched girder and the inaccuracy of the action effect model. The time invariant reliability analysis is based on Turkstra's rule for combinations of snow and wind actions. The time variant analysis describes snow and wind actions by jump processes with intermittencies. Assuming a 50-year lifetime, the obtained values of the reliability index b vary within the range from 3.95 up to 5.56. The cross-profile IPE 330 designed according to Eurocodes seems to be adequate. It appears that the time invariant reliability analysis based on Turkstra's rule provides considerably lower values of b than those obtained by the time variant analysis.

  19. Analysis of reliability of professor recommendation letters based on concordance with self-introduction letter.

    Kim, Sang Hyun


    The purpose of this study was to examine the concordance between a checklist's categories of professor recommendation letters and characteristics of the self-introduction letter. Checklists of professor recommendation letters were analyzed and classified into cognitive, social, and affective domains. Simple correlation was performed to determine whether the characteristics of the checklists were concordant with those of the self-introduction letter. The difference in ratings of the checklists by pass or fail grades was analyzed by independent sample t-test. Logistic regression analysis was performed to determine whether a pass or fail grade was influenced by ratings on the checklists. The Cronbach alpha value of the checklists was 0.854. Initiative, as an affective domain, in the professor's recommendation letter was highly ranked among the six checklist categories. Self-directed learning in the self-introduction letter was influenced by a pass or fail grade by logistic regression analysis (pprofessor recommendation letters and the sum of all characteristics in the self-introduction letter.

  20. SPARK: Sparsity-based analysis of reliable k-hubness and overlapping network structure in brain functional connectivity.

    Lee, Kangjoo; Lina, Jean-Marc; Gotman, Jean; Grova, Christophe


    Functional hubs are defined as the specific brain regions with dense connections to other regions in a functional brain network. Among them, connector hubs are of great interests, as they are assumed to promote global and hierarchical communications between functionally specialized networks. Damage to connector hubs may have a more crucial effect on the system than does damage to other hubs. Hubs in graph theory are often identified from a correlation matrix, and classified as connector hubs when the hubs are more connected to regions in other networks than within the networks to which they belong. However, the identification of hubs from functional data is more complex than that from structural data, notably because of the inherent problem of multicollinearity between temporal dynamics within a functional network. In this context, we developed and validated a method to reliably identify connectors and corresponding overlapping network structure from resting-state fMRI. This new method is actually handling the multicollinearity issue, since it does not rely on counting the number of connections from a thresholded correlation matrix. The novelty of the proposed method is that besides counting the number of networks involved in each voxel, it allows us to identify which networks are actually involved in each voxel, using a data-driven sparse general linear model in order to identify brain regions involved in more than one network. Moreover, we added a bootstrap resampling strategy to assess statistically the reproducibility of our results at the single subject level. The unified framework is called SPARK, i.e. SParsity-based Analysis of Reliable k-hubness, where k-hubness denotes the number of networks overlapping in each voxel. The accuracy and robustness of SPARK were evaluated using two dimensional box simulations and realistic simulations that examined detection of artificial hubs generated on real data. Then, test/retest reliability of the method was assessed

  1. Reliability Analysis and Optimal Design of Monolithic Vertical Wall Breakwaters

    Sørensen, John Dalsgaard; Burcharth, Hans F.; Christiani, E.


    Reliability analysis and reliability-based design of monolithic vertical wall breakwaters are considered. Probabilistic models of the most important failure modes, sliding failure, failure of the foundation and overturning failure are described . Relevant design variables are identified and relia......Reliability analysis and reliability-based design of monolithic vertical wall breakwaters are considered. Probabilistic models of the most important failure modes, sliding failure, failure of the foundation and overturning failure are described . Relevant design variables are identified...


    LI Hong-shuang; L(U) Zhen-zhou; YUE Zhu-feng


    Support vector machine (SVM) was introduced to analyze the reliability of the implicit performance function, which is difficult to implement by the classical methods such as the first order reliability method (FORM) and the Monte Carlo simulation (MCS). As a classification method where the underlying structural risk minimization inference rule is employed, SVM possesses excellent learning capacity with a small amount of information and good capability of generalization over the complete data. Hence,two approaches, i.e., SVM-based FORM and SVM-based MCS, were presented for the structural reliability analysis of the implicit limit state function. Compared to the conventional response surface method (RSM) and the artificial neural network (ANN), which are widely used to replace the implicit state function for alleviating the computation cost,the more important advantages of SVM are that it can approximate the implicit function with higher precision and better generalization under the small amount of information and avoid the "curse of dimensionality". The SVM-based reliability approaches can approximate the actual performance function over the complete sampling data with the decreased number of the implicit performance function analysis (usually finite element analysis), and the computational precision can satisfy the engineering requirement, which are demonstrated by illustrations.

  3. The quantitative failure of human reliability analysis

    Bennett, C.T.


    This philosophical treatise argues the merits of Human Reliability Analysis (HRA) in the context of the nuclear power industry. Actually, the author attacks historic and current HRA as having failed in informing policy makers who make decisions based on risk that humans contribute to systems performance. He argues for an HRA based on Bayesian (fact-based) inferential statistics, which advocates a systems analysis process that employs cogent heuristics when using opinion, and tempers itself with a rational debate over the weight given subjective and empirical probabilities.

  4. Design and analysis of the reliability of on-board computer system based on Markov-model

    MA Xiu-juan; CAO Xi-bin; ZHAO Guo-liang


    An on-board computer system should have such advantages as light weight, small volume and low power to meet the demand of micro-satellites. This paper, based on specific characteristics of Stereo Mapping Micro-Satellite ( SMMS), describes the on-board computer system with its advantage of having centralized and distributed control in the same system and analyzes its reliability based on a Markov model in order to provide a theoretical foundation for a reliable design. The on-board computer system has been put into use in principle prototype model of Stereo Mapping Micro-Satellite and has already been debugged. All indexes meet the requirements of the design.

  5. A Novel Two-Terminal Reliability Analysis for MANET

    Xibin Zhao; Zhiyang You; Hai Wan


    Mobile ad hoc network (MANET) is a dynamic wireless communication network. Because of the dynamic and infrastructureless characteristics, MANET is vulnerable in reliability. This paper presents a novel reliability analysis for MANET. The node mobility effect and the node reliability based on a real MANET platform are modeled and analyzed. An effective Monte Carlo method for reliability analysis is proposed. A detailed evaluation is performed in terms of the experiment results.

  6. A Novel Two-Terminal Reliability Analysis for MANET

    Xibin Zhao


    Full Text Available Mobile ad hoc network (MANET is a dynamic wireless communication network. Because of the dynamic and infrastructureless characteristics, MANET is vulnerable in reliability. This paper presents a novel reliability analysis for MANET. The node mobility effect and the node reliability based on a real MANET platform are modeled and analyzed. An effective Monte Carlo method for reliability analysis is proposed. A detailed evaluation is performed in terms of the experiment results.

  7. Solving reliability analysis problems in the polar space

    Ghasem Ezzati; Musa Mammadov; Siddhivinayak Kulkarni


    An optimization model that is widely used in engineering problems is Reliability-Based Design Optimization (RBDO). Input data of the RBDO is non-deterministic and constraints are probabilistic. The RBDO aims at minimizing cost ensuring that reliability is at least an accepted level. Reliability analysis is an important step in two-level RBDO approaches. Although many methods have been introduced to apply in reliability analysis loop of the RBDO, there are still many drawbacks in their efficie...

  8. A study and development of Windows based program of reliability analysis for assessing service life of cracked connections

    Suchart Limkatanyu


    Full Text Available The development of a Windows based framework to undertake probabilistic fracture mechanics studies is reported. The reliability method used in the program is Monte-Carlo Simulation method. The results of the computation of the program are stress intensity factor, reliability index and probability of failure. The probabilistic studies of cruciform welded joint containing Lack of Penetration (LOP defect and T-butt geometry containing surface crack at weld toe are performed in both critical crack growth and fatigue problem. The results can be used as an indicator for assuring the safety of this particular type of connection. It can also be used as a design criterion for the connection.

  9. An integrated reliability-based design optimization of offshore towers

    Karadeniz, Halil [Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft (Netherlands)], E-mail:; Togan, Vedat [Department of Civil Engineering, Karadeniz Technical University, Trabzon (Turkey); Vrouwenvelder, Ton [Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft (Netherlands)


    After recognizing the uncertainty in the parameters such as material, loading, geometry and so on in contrast with the conventional optimization, the reliability-based design optimization (RBDO) concept has become more meaningful to perform an economical design implementation, which includes a reliability analysis and an optimization algorithm. RBDO procedures include structural analysis, reliability analysis and sensitivity analysis both for optimization and for reliability. The efficiency of the RBDO system depends on the mentioned numerical algorithms. In this work, an integrated algorithms system is proposed to implement the RBDO of the offshore towers, which are subjected to the extreme wave loading. The numerical strategies interacting with each other to fulfill the RBDO of towers are as follows: (a) a structural analysis program, SAPOS, (b) an optimization program, SQP and (c) a reliability analysis program based on FORM. A demonstration of an example tripod tower under the reliability constraints based on limit states of the critical stress, buckling and the natural frequency is presented.

  10. Reliability Analysis of Slope Stability by Central Point Method

    Li, Chunge; WU Congliang


    Given uncertainty and variability of the slope stability analysis parameter, the paper proceed from the perspective of probability theory and statistics based on the reliability theory. Through the central point method of reliability analysis, performance function about the reliability of slope stability analysis is established. What’s more, the central point method and conventional limit equilibrium methods do comparative analysis by calculation example. The approach’s numerical ...

  11. Creep-rupture reliability analysis

    Peralta-Duran, A.; Wirsching, P. H.


    A probabilistic approach to the correlation and extrapolation of creep-rupture data is presented. Time temperature parameters (TTP) are used to correlate the data, and an analytical expression for the master curve is developed. The expression provides a simple model for the statistical distribution of strength and fits neatly into a probabilistic design format. The analysis focuses on the Larson-Miller and on the Manson-Haferd parameters, but it can be applied to any of the TTP's. A method is developed for evaluating material dependent constants for TTP's. It is shown that optimized constants can provide a significant improvement in the correlation of the data, thereby reducing modelling error. Attempts were made to quantify the performance of the proposed method in predicting long term behavior. Uncertainty in predicting long term behavior from short term tests was derived for several sets of data. Examples are presented which illustrate the theory and demonstrate the application of state of the art reliability methods to the design of components under creep.

  12. Reliability Analysis of Elasto-Plastic Structures


    . Failure of this type of system is defined either as formation of a mechanism or by failure of a prescribed number of elements. In the first case failure is independent of the order in which the elements fail, but this is not so by the second definition. The reliability analysis consists of two parts...... are described and the two definitions of failure can be used by the first formulation, but only the failure definition based on formation of a mechanism by the second formulation. The second part of the reliability analysis is an estimate of the failure probability for the structure on the basis...... are obtained if the failure mechanisms are used. Lower bounds can be calculated on the basis of series systems where the elements are the non-failed elements in a non-failed structure (see Augusti & Baratta [3])....

  13. Modified Bayesian Kriging for Noisy Response Problems for Reliability Analysis


    surrogate model is used to do the MCS prediction for the reliability analysis for the sampling- based reliability-based design optimization ( RBDO ) method...D., Choi, K. K., Noh, Y., & Zhao, L. (2011). Sampling-based stochastic sensitivity analysis using score functions for RBDO problems with correlated...K., and Zhao, L., (2011). Sampling- based RBDO using the stochastic sensitivity analysis and dynamic Kriging method. Structural and

  14. Reliability analysis of wastewater treatment plants.

    Oliveira, Sílvia C; Von Sperling, Marcos


    This article presents a reliability analysis of 166 full-scale wastewater treatment plants operating in Brazil. Six different processes have been investigated, comprising septic tank+anaerobic filter, facultative pond, anaerobic pond+facultative pond, activated sludge, upflow anaerobic sludge blanket (UASB) reactors alone and UASB reactors followed by post-treatment. A methodology developed by Niku et al. [1979. Performance of activated sludge process and reliability-based design. J. Water Pollut. Control Assoc., 51(12), 2841-2857] is used for determining the coefficients of reliability (COR), in terms of the compliance of effluent biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and fecal or thermotolerant coliforms (FC) with discharge standards. The design concentrations necessary to meet the prevailing discharge standards and the expected compliance percentages have been calculated from the COR obtained. The results showed that few plants, under the observed operating conditions, would be able to present reliable performances considering the compliance with the analyzed standards. The article also discusses the importance of understanding the lognormal behavior of the data in setting up discharge standards, in interpreting monitoring results and compliance with the legislation.

  15. Reliability analysis on resonance for low-pressure compressor rotor blade based on least squares support vector machine with leave-one-out cross-validation

    Haifeng Gao


    Full Text Available This research article analyzes the resonant reliability at the rotating speed of 6150.0 r/min for low-pressure compressor rotor blade. The aim is to improve the computational efficiency of reliability analysis. This study applies least squares support vector machine to predict the natural frequencies of the low-pressure compressor rotor blade considered. To build a more stable and reliable least squares support vector machine model, leave-one-out cross-validation is introduced to search for the optimal parameters of least squares support vector machine. Least squares support vector machine with leave-one-out cross-validation is presented to analyze the resonant reliability. Additionally, the modal analysis at the rotating speed of 6150.0 r/min for the rotor blade is considered as a tandem system to simplify the analysis and design process, and the randomness of influence factors on frequencies, such as material properties, structural dimension, and operating condition, is taken into consideration. Back-propagation neural network is compared to verify the proposed approach based on the same training and testing sets as least squares support vector machine with leave-one-out cross-validation. Finally, the statistical results prove that the proposed approach is considered to be effective and feasible and can be applied to structural reliability analysis.

  16. System reliability analysis for kinematic performance of planar mechanisms

    ZHANG YiMin; HUANG XianZhen; ZHANG XuFang; HE XiangDong; WEN BangChun


    Based on the reliability and mechanism kinematic accuracy theories, we propose a general methodology for system reliability analysis of kinematic performance of planar mechanisms. The loop closure equations are used to estimate the kinematic performance errors of planar mechanisms. Reliability and system reliability theories are introduced to develop the limit state functions (LSF) for failure of kinematic performance qualities. The statistical fourth moment method and the Edgeworth series technique are used on system reliability analysis for kinematic performance of planar mechanisms, which relax the restrictions of probability distribution of design variables. Finally, the practicality, efficiency and accuracy of the proposed method are demonstrated by numerical examples.

  17. Reliability Analysis of Money Habitudes

    Delgadillo, Lucy M.; Bushman, Brittani S.


    Use of the Money Habitudes exercise has gained popularity among various financial professionals. This article reports on the reliability of this resource. A survey administered to young adults at a western state university was conducted, and each Habitude or "domain" was analyzed using Cronbach's alpha procedures. Results showed all six…

  18. Reliability Analysis of Money Habitudes

    Delgadillo, Lucy M.; Bushman, Brittani S.


    Use of the Money Habitudes exercise has gained popularity among various financial professionals. This article reports on the reliability of this resource. A survey administered to young adults at a western state university was conducted, and each Habitude or "domain" was analyzed using Cronbach's alpha procedures. Results showed all six…

  19. Mechanical reliability analysis of tubes intended for hydrocarbons

    Nahal, Mourad; Khelif, Rabia [Badji Mokhtar University, Annaba (Algeria)


    Reliability analysis constitutes an essential phase in any study concerning reliability. Many industrialists evaluate and improve the reliability of their products during the development cycle - from design to startup (design, manufacture, and exploitation) - to develop their knowledge on cost/reliability ratio and to control sources of failure. In this study, we obtain results for hardness, tensile, and hydrostatic tests carried out on steel tubes for transporting hydrocarbons followed by statistical analysis. Results obtained allow us to conduct a reliability study based on resistance request. Thus, index of reliability is calculated and the importance of the variables related to the tube is presented. Reliability-based assessment of residual stress effects is applied to underground pipelines under a roadway, with and without active corrosion. Residual stress has been found to greatly increase probability of failure, especially in the early stages of pipe lifetime.

  20. Combination of structural reliability and interval analysis

    Zhiping Qiu; Di Yang; saac Elishakoff


    In engineering applications,probabilistic reliability theory appears to be presently the most important method,however,in many cases precise probabilistic reliability theory cannot be considered as adequate and credible model of the real state of actual affairs.In this paper,we developed a hybrid of probabilistic and non-probabilistic reliability theory,which describes the structural uncertain parameters as interval variables when statistical data are found insufficient.By using the interval analysis,a new method for calculating the interval of the structural reliability as well as the reliability index is introduced in this paper,and the traditional probabilistic theory is incorporated with the interval analysis.Moreover,the new method preserves the useful part of the traditional probabilistic reliability theory,but removes the restriction of its strict requirement on data acquisition.Example is presented to demonstrate the feasibility and validity of the proposed theory.

  1. Integrated Reliability and Risk Analysis System (IRRAS)

    Russell, K D; McKay, M K; Sattison, M.B. Skinner, N.L.; Wood, S T [EG and G Idaho, Inc., Idaho Falls, ID (United States); Rasmuson, D M [Nuclear Regulatory Commission, Washington, DC (United States)


    The Integrated Reliability and Risk Analysis System (IRRAS) is a state-of-the-art, microcomputer-based probabilistic risk assessment (PRA) model development and analysis tool to address key nuclear plant safety issues. IRRAS is an integrated software tool that gives the user the ability to create and analyze fault trees and accident sequences using a microcomputer. This program provides functions that range from graphical fault tree construction to cut set generation and quantification. Version 1.0 of the IRRAS program was released in February of 1987. Since that time, many user comments and enhancements have been incorporated into the program providing a much more powerful and user-friendly system. This version has been designated IRRAS 4.0 and is the subject of this Reference Manual. Version 4.0 of IRRAS provides the same capabilities as Version 1.0 and adds a relational data base facility for managing the data, improved functionality, and improved algorithm performance.

  2. Location-based reliability differentiated service for wireless sensor networks

    Yong ZENG; Jianfeng MA


    Designing reliability differentiated services for missions with different reliability requirements has become a hot topic in wireless sensor networks. Combined with a location-based routing mechanism, a quantified model without full network topology is proposed to evaluate reliability. By introducing a virtual reference point, the data transfer is limited in a specified area. The reliability function of the area is given. A detailed analysis shows that the function increases quadratically with the distance between the source node and the reference node. A reliability differentiated service mechanism is then proposed. The simulation results show the efficiency of the proposed mechanism.

  3. Reliability Analysis of Adhesive Bonded Scarf Joints

    Kimiaeifar, Amin; Toft, Henrik Stensgaard; Lund, Erik;


    A probabilistic model for the reliability analysis of adhesive bonded scarfed lap joints subjected to static loading is developed. It is representative for the main laminate in a wind turbine blade subjected to flapwise bending. The structural analysis is based on a three dimensional (3D) finite...... the FEA model, and a sensitivity analysis on the influence of various geometrical parameters and material properties on the maximum stress is conducted. Because the yield behavior of many polymeric structural adhesives is dependent on both deviatoric and hydrostatic stress components, different ratios...... of the compressive to tensile adhesive yield stresses in the failure criterion are considered. It is shown that the chosen failure criterion, the scarf angle and the load are significant for the assessment of the probability of failure....

  4. Analysis on testing and operational reliability of software

    ZHAO Jing; LIU Hong-wei; CUI Gang; WANG Hui-qiang


    Software reliability was estimated based on NHPP software reliability growth models. Testing reliability and operational reliability may be essentially different. On the basis of analyzing similarities and differences of the testing phase and the operational phase, using the concept of operational reliability and the testing reliability, different forms of the comparison between the operational failure ratio and the predicted testing failure ratio were conducted, and the mathematical discussion and analysis were performed in detail. Finally, software optimal release was studied using software failure data. The results show that two kinds of conclusions can be derived by applying this method, one conclusion is to continue testing to meet the required reliability level of users, and the other is that testing stops when the required operational reliability is met, thus the testing cost can be reduced.

  5. Integrated Methodology for Software Reliability Analysis

    Marian Pompiliu CRISTESCU


    Full Text Available The most used techniques to ensure safety and reliability of the systems are applied together as a whole, and in most cases, the software components are usually overlooked or to little analyzed. The present paper describes the applicability of fault trees analysis software system, analysis defined as Software Fault Tree Analysis (SFTA, fault trees are evaluated using binary decision diagrams, all of these being integrated and used with help from Java library reliability.

  6. Reliability of digital reactor protection system based on extenics.

    Zhao, Jing; He, Ya-Nan; Gu, Peng-Fei; Chen, Wei-Hua; Gao, Feng


    After the Fukushima nuclear accident, safety of nuclear power plants (NPPs) is widespread concerned. The reliability of reactor protection system (RPS) is directly related to the safety of NPPs, however, it is difficult to accurately evaluate the reliability of digital RPS. The method is based on estimating probability has some uncertainties, which can not reflect the reliability status of RPS dynamically and support the maintenance and troubleshooting. In this paper, the reliability quantitative analysis method based on extenics is proposed for the digital RPS (safety-critical), by which the relationship between the reliability and response time of RPS is constructed. The reliability of the RPS for CPR1000 NPP is modeled and analyzed by the proposed method as an example. The results show that the proposed method is capable to estimate the RPS reliability effectively and provide support to maintenance and troubleshooting of digital RPS system.

  7. Reliability analysis of an associated system

    陈长杰; 魏一鸣; 蔡嗣经


    Based on engineering reliability of large complex system and distinct characteristic of soft system, some new conception and theory on the medium elements and the associated system are created. At the same time, the reliability logic model of associated system is provided. In this paper, through the field investigation of the trial operation, the engineering reliability of the paste fill system in No.2 mine of Jinchuan Non-ferrous Metallic Corporation is analyzed by using the theory of associated system.


    Ronald L. Boring; David I. Gertman; Katya Le Blanc


    This paper provides a characterization of human reliability analysis (HRA) issues for computerized procedures in nuclear power plant control rooms. It is beyond the scope of this paper to propose a new HRA approach or to recommend specific methods or refinements to those methods. Rather, this paper provides a review of HRA as applied to traditional paper-based procedures, followed by a discussion of what specific factors should additionally be considered in HRAs for computerized procedures. Performance shaping factors and failure modes unique to computerized procedures are highlighted. Since there is no definitive guide to HRA for paper-based procedures, this paper also serves to clarify the existing guidance on paper-based procedures before delving into the unique aspects of computerized procedures.

  9. Reliability-Based Topology Optimization With Uncertainties

    Bae, Kyoungryun [JAEIK Information and Communication Co. Ltd., Seoul (Korea, Republic of); Wang, Semyung [Kwangju Institute of Science and Technology, Kwangju (Korea, Republic of); Choi, Kyung K. [Univ. of Iowa, Iowa (United States)


    A probabilistic optimal design modeled with finite elements is presented. A 2-D finite element model is constructed for topology optimization. Young's modulus, thickness and loading are considered as uncertain variables. The uncertain variable means that the variable has a variance on a certain point. In order to compute reliability constraints, two methods-RIA, PMA-are widely used. To find reliability index easily, the limit state function is linearly approximated at the each iteration. This approximation method is called as the first order reliability method (FORM), which is widely used in reliability based design optimizations (RBDO)

  10. A Reliability-based Framework for Multi-path Routing Analysis in Mobile Ad-Hoc Networks

    Caleffi, Marcello; Paura, Luigi


    Unlike traditional routing procedures that, at the best, single out a unique route, multi-path routing protocols discover proactively several alternative routes. It has been recognized that multi-path routing can be more efficient than traditional one mainly for mobile ad hoc networks, where route failure events are frequent. Most studies in the area of multi-path routing focus on heuristic methods, and the performances of these strategies are commonly evaluated by numerical simulations. The need of a theoretical analysis motivates such a paper, which proposes to resort to the terminal-pair routing reliability as performance metric. This metric allows one to assess the performance gain due to the availability of route diversity. By resorting to graph theory, we propose an analytical framework to evaluate the tolerance of multi-path route discovery processes against route failures for mobile ad hoc networks. Moreover, we derive a useful bound to easily estimate the performance improvements achieved by multi-pa...

  11. Reliability Sensitivity Analysis for Location Scale Family

    洪东跑; 张海瑞


    Many products always operate under various complex environment conditions. To describe the dynamic influence of environment factors on their reliability, a method of reliability sensitivity analysis is proposed. In this method, the location parameter is assumed as a function of relevant environment variables while the scale parameter is assumed as an un- known positive constant. Then, the location parameter function is constructed by using the method of radial basis function. Using the varied environment test data, the log-likelihood function is transformed to a generalized linear expression by de- scribing the indicator as Poisson variable. With the generalized linear model, the maximum likelihood estimations of the model coefficients are obtained. With the reliability model, the reliability sensitivity is obtained. An instance analysis shows that the method is feasible to analyze the dynamic variety characters of reliability along with environment factors and is straightforward for engineering application.

  12. Reliability-Based Optimization of Series Systems of Parallel Systems

    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...... problems are described. Numerical tests indicate that a sequential technique called the bounds iteration method (BIM) is particularly fast and stable....

  13. Reliability-Analysis of Offshore Structures using Directional Loads

    Sørensen, John Dalsgaard; Bloch, Allan; Sterndorff, M. J.


    Reliability analyses of offshore structures such as steel jacket platforms are usually performed using stochastic models for the wave loads based on the omnidirectional wave height. However, reliability analyses with respect to structural failure modes such as total collapse of a structure...... heights from the central part of the North Sea. It is described how the stochastic model for the directional wave heights can be used in a reliability analysis where total collapse of offshore steel jacket platforms is considered....

  14. Statistical analysis on reliability and serviceability of caterpillar tractor

    WANG Jinwu; LIU Jiafu; XU Zhongxiang


    For further understanding reliability and serviceability of tractor and to furnish scientific and technical theories, based on the promotion and application of it, the following experiments and statistical analysis on reliability (reliability and MTBF) serviceability (service and MTTR) of Donfanghong-1002 and Dongfanghong-802 were conducted. The result showed that the intervals of average troubles of these two tractors were 182.62 h and 160.2 h, respectively, and the weakest assembly of them was engine part.

  15. Simulation Approach to Mission Risk and Reliability Analysis Project

    National Aeronautics and Space Administration — It is proposed to develop and demonstrate an integrated total-system risk and reliability analysis approach that is based on dynamic, probabilistic simulation. This...

  16. The stability safety factor calibration based on the reliability index

    Tong Xiaolong; Fang Zhi


    When the bridge structure stability safety factor of the first type is 4,the research that whether the structure reliability index will reach target reliability index under the more-likely-to-happen collapse situation of the second type is necessary. The stability calculations of the first and the second type are made respectively for single layer and single span rigid frame bridge. Based on the critical load obtained from the stability calculation of the first type,the stability safety factor of the first type is taken as 4,and the first order reliability method is used to program and calculate the reliability index. Then,the load effect under the stability reliability index cal-culation of the first type and the critical load of the second type are employed to calculate the reliability index of the second type. The evaluation of structure stability safety factor is discussed according to reliability index. Based on the discussion above,parameter analysis of the stable critical loads of two types is made,and the in-fluence of critical load change on reliability index is researched. The result shows that stability analysis should identify collapse state;when the stability safety factor of the first type is 4,but the structure has the collapse of the second type,the reliability index cannot be ensured to reach the target reliability index under certain condi-tions.


    Bowerman, P. N.


    RELAV (Reliability/Availability Analysis Program) is a comprehensive analytical tool to determine the reliability or availability of any general system which can be modeled as embedded k-out-of-n groups of items (components) and/or subgroups. Both ground and flight systems at NASA's Jet Propulsion Laboratory have utilized this program. RELAV can assess current system performance during the later testing phases of a system design, as well as model candidate designs/architectures or validate and form predictions during the early phases of a design. Systems are commonly modeled as System Block Diagrams (SBDs). RELAV calculates the success probability of each group of items and/or subgroups within the system assuming k-out-of-n operating rules apply for each group. The program operates on a folding basis; i.e. it works its way towards the system level from the most embedded level by folding related groups into single components. The entire folding process involves probabilities; therefore, availability problems are performed in terms of the probability of success, and reliability problems are performed for specific mission lengths. An enhanced cumulative binomial algorithm is used for groups where all probabilities are equal, while a fast algorithm based upon "Computing k-out-of-n System Reliability", Barlow & Heidtmann, IEEE TRANSACTIONS ON RELIABILITY, October 1984, is used for groups with unequal probabilities. Inputs to the program include a description of the system and any one of the following: 1) availabilities of the items, 2) mean time between failures and mean time to repairs for the items from which availabilities are calculated, 3) mean time between failures and mission length(s) from which reliabilities are calculated, or 4) failure rates and mission length(s) from which reliabilities are calculated. The results are probabilities of success of each group and the system in the given configuration. RELAV assumes exponential failure distributions for

  18. 基于人差错纠正能力的人因可靠性模型研究%Human Reliability Method Analysis Based on Human Error Correcting Ability

    陈炉云; 张裕芳


    Based on the theory of time sequence and error correcting ability character of the human operator behaviors in man-machine system, combining the key performance shaping factor analysis, the human reliability analysis of the vessel chamber is investigated. By the time sequence parameter and error correcting parameter in the human errors analysis, the operator behaviors shaping model of man-machine system and human errors event tree are proposed. By the error correcting ability analysis, the quantitative model and allowance theory in human reliability analysis are discussed. In the end, with the monitoring task of the operation desk in the vessel chamber as an example, a human reliability analysis was conducted to quantitatively assess the mission reliability of the operator.%根据人-机系统中人的操作行为具有时序性和差错可纠正性的特点,结合船舶舱室行为形成主因子,开展船舶舱室人因可靠性研究.以人因失误的时序性和差错纠正参数为基础,建立人-机系统中操作者行为模式和人因失误事件树模型.通过对人的差错纠正能力的分析,开展人因可靠性量化模型纠正理论研究.最后,以船舶舱室操作台的监控任务人因可靠性为例进行量化计算,定量评估操作人员执行任务的可靠度.

  19. Evaluating some Reliability Analysis Methodologies in Seismic Design

    A. E. Ghoulbzouri


    Full Text Available Problem statement: Accounting for uncertainties that are present in geometric and material data of reinforced concrete buildings is performed in this study within the context of performance based seismic engineering design. Approach: Reliability of the expected performance state is assessed by using various methodologies based on finite element nonlinear static pushover analysis and specialized reliability software package. Reliability approaches that were considered included full coupling with an external finite element code and surface response based methods in conjunction with either first order reliability method or importance sampling method. Various types of probability distribution functions that model parameters uncertainties were introduced. Results: The probability of failure according to the used reliability analysis method and to the selected distribution of probabilities was obtained. Convergence analysis of the importance sampling method was performed. The required duration of analysis as function of the used reliability method was evaluated. Conclusion/Recommendations: It was found that reliability results are sensitive to the used reliability analysis method and to the selected distribution of probabilities. Durations of analysis for coupling methods were found to be higher than those associated to surface response based methods; one should however include time needed to derive these lasts. For the reinforced concrete building considered in this study, it was found that significant variations exist between all the considered reliability methodologies. The full coupled importance sampling method is recommended, but the first order reliability method applied on a surface response model can be used with good accuracy. Finally, the distributions of probabilities should be carefully identified since giving the mean and the standard deviation were found to be insufficient.

  20. Multi-Disciplinary System Reliability Analysis

    Mahadevan, Sankaran; Han, Song


    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.

  1. Reliability Analysis of DOOF for Weibull Distribution

    陈文华; 崔杰; 樊小燕; 卢献彪; 相平


    Hierarchical Bayesian method for estimating the failure probability under DOOF by taking the quasi-Beta distribution as the prior distribution is proposed in this paper. The weighted Least Squares Estimate method was used to obtain the formula for computing reliability distribution parameters and estimating the reliability characteristic values under DOOF. Taking one type of aerospace electrical connector as an example, the correctness of the above method through statistical analysis of electrical connector accelerated life test data was verified.

  2. [Qualitative analysis: theory, steps and reliability].

    Minayo, Maria Cecília de Souza


    This essay seeks to conduct in-depth analysis of qualitative research, based on benchmark authors and the author's own experience. The hypothesis is that in order for an analysis to be considered reliable, it needs to be based on structuring terms of qualitative research, namely the verbs 'comprehend' and 'interpret', and the nouns 'experience', 'common sense' and 'social action'. The 10 steps begin with the construction of the scientific object by its inclusion on the national and international agenda; the development of tools that make the theoretical concepts tangible; conducting field work that involves the researcher empathetically with the participants in the use of various techniques and approaches, making it possible to build relationships, observations and a narrative with perspective. Finally, the author deals with the analysis proper, showing how the object, which has already been studied in all the previous steps, should become a second-order construct, in which the logic of the actors in their diversity and not merely their speech predominates. The final report must be a theoretic, contextual, concise and clear narrative.

  3. Reliability-based design optimization strategies based on FORM: a review

    Lopez, Rafael Holdorf; BECK, André Teófilo


    In deterministic optimization, the uncertainties of the structural system (i.e. dimension, model, material, loads, etc) are not explicitly taken into account. Hence, resulting optimal solutions may lead to reduced reliability levels. The objective of reliability based design optimization (RBDO) is to optimize structures guaranteeing that a minimum level of reliability, chosen a priori by the designer, is maintained. Since reliability analysis using the First Order Reliability Method (FORM) is...

  4. Reliability analysis of flood defence systems

    Steenbergen, H.M.G.M.; Lassing, B.L.; Vrouwenvelder, A.C.W.M.; Waarts, P.H.


    In recent years an advanced program for the reliability analysis of flood defence systems has been under development. This paper describes the global data requirements for the application and the setup of the models. The analysis generates the probability of system failure and the contribution of ea

  5. Reliability Analysis of High Rockfill Dam Stability

    Ping Yi


    Full Text Available A program 3DSTAB combining slope stability analysis and reliability analysis is developed and validated. In this program, the limit equilibrium method is utilized to calculate safety factors of critical slip surfaces. The first-order reliability method is used to compute reliability indexes corresponding to critical probabilistic surfaces. When derivatives of the performance function are calculated by finite difference method, the previous iteration’s critical slip surface is saved and used. This sequential approximation strategy notably improves efficiency. Using this program, the stability reliability analyses of concrete faced rockfill dams and earth core rockfill dams with different heights and different slope ratios are performed. The results show that both safety factors and reliability indexes decrease as the dam’s slope increases at a constant height and as the dam’s height increases at a constant slope. They decrease dramatically as the dam height increases from 100 m to 200 m while they decrease slowly once the dam height exceeds 250 m, which deserves attention. Additionally, both safety factors and reliability indexes of the upstream slope of earth core rockfill dams are higher than that of the downstream slope. Thus, the downstream slope stability is the key failure mode for earth core rockfill dams.

  6. Seismic reliability analysis of large electric power systems

    何军; 李杰


    Based on the De. Morgan laws and Boolean simplification, a recursive decomposition method is introduced in this paper to identity the main exclusive safe paths and failed paths of a network. The reliability or the reliability bound of a network can be conveniently expressed as the summation of the joint probabilities of these paths. Under the multivariate normal distribution assumption, a conditioned reliability index method is developed to evaluate joint probabilities of various exclusive safe paths and failed paths, and, finally, the seismic reliability or the reliability bound of an electric power system.Examples given in thc paper show that the method is very simple and provides accurate results in the seismic reliability analysis.



    performance of any structural system be eva ... by the Joint crete slabs, bending, shear, deflection, reliability, design codes. ement such as ... could be sensitive to this distribution. Table 1: ..... Ang, A. H-S and Tang, W. H. Probability Concepts in.

  8. Culture Representation in Human Reliability Analysis

    David Gertman; Julie Marble; Steven Novack


    Understanding human-system response is critical to being able to plan and predict mission success in the modern battlespace. Commonly, human reliability analysis has been used to predict failures of human performance in complex, critical systems. However, most human reliability methods fail to take culture into account. This paper takes an easily understood state of the art human reliability analysis method and extends that method to account for the influence of culture, including acceptance of new technology, upon performance. The cultural parameters used to modify the human reliability analysis were determined from two standard industry approaches to cultural assessment: Hofstede’s (1991) cultural factors and Davis’ (1989) technology acceptance model (TAM). The result is called the Culture Adjustment Method (CAM). An example is presented that (1) reviews human reliability assessment with and without cultural attributes for a Supervisory Control and Data Acquisition (SCADA) system attack, (2) demonstrates how country specific information can be used to increase the realism of HRA modeling, and (3) discusses the differences in human error probability estimates arising from cultural differences.

  9. A single loop reliability-based design optimization using EPM and MPP-based PSO

    Liao, Kuo-Wei; Ivan,Gautama


    A reliability-based design optimization (RBDO) incorporates a probabilistic analysis with an optimization technique to find a best design within a reliable design space. However, the computational cost of an RBDO task is often expensive compared to a deterministic optimization, which is mainly due to the reliability analysis performed inside the optimization loop. Theoretically, the reliability of a given design point can be obtained through a multidimensional integration. Integration with mu...

  10. Process control using reliability based control charts

    J.K. Jacob


    Full Text Available Purpose: The paper presents the method to monitor the mean time between failures (MTBF and detect anychange in intensity parameter. Here, a control chart procedure is presented for process reliability monitoring.Control chart based on different distributions are also considered and were used in decision making. Results anddiscussions are presented based on the case study at different industries.Design/methodology/approach: The failure occurrence process can be modeled by different distributions likehomogeneous Poisson process, Weibull model etc. In each case the aim is to monitor the mean time betweenfailure (MTBF and detect any change in intensity parameter. When the process can be described by a Poissonprocess the time between failures will be exponential and can be used for reliability monitoring.Findings: In this paper, a new procedure based on the monitoring of time to observe r failures is also proposedand it can be more appropriate for reliability monitoring.Practical implications: This procedure is useful and more sensitive when compared with the λ-chart although itwill wait until r failures for a decision. These charts can be regarded as powerful tools for reliability monitoring.λr gives more accurate results than λ-chart.Originality/value: Adopting these measures to system of equipments can increase the reliability and availabilityof the system results in economic gain. A homogeneous Poisson process is usually used to model the failureoccurrence process with certain intensity.

  11. Reliability-based design optimization using convex approximations and sequential optimization and reliability assessment method

    Cho, Tae Min; Lee, Byung Chai [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)


    In this study, an effective method for reliability-based design optimization (RBDO) is proposed enhancing sequential optimization and reliability assessment (SORA) method by convex approximations. In SORA, reliability estimation and deterministic optimization are performed sequentially. The sensitivity and function value of probabilistic constraint at the most probable point (MPP) are obtained in the reliability analysis loop. In this study, the convex approximations for probabilistic constraint are constructed by utilizing the sensitivity and function value of the probabilistic constraint at the MPP. Hence, the proposed method requires much less function evaluations of probabilistic constraints in the deterministic optimization than the original SORA method. The efficiency and accuracy of the proposed method were verified through numerical examples

  12. Dynamic reliability of digital-based transmitters

    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)


    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.

  13. Reliability-Based Design of Coastal Structures

    Burcharth, H. F.


    The objective of this paper is to introduce the application of reliability theory for conceptual design and evaluation of coastal structures. It is without the scope to discuss the validity and quality of the various design formulae available for coastal structures. The contents of the paper...... Engineering. Burcharth, H.F. (1993) Design of Breakwaters. Aalborg University. Department of Civil Engineering. Aalborg, Denmark. (Note). Burcbarth, H.F., Dalsgaard S9lrensen, J ., Cbristiani, E. (1995} Application for reliability analysis for optimal design of monolithic vertical wall breakwaters....... Proceedings Conference of Port and Coastal Engineering in developing countries. Rio de Janeiro, Brazil, 1995....

  14. Event/Time/Availability/Reliability-Analysis Program

    Viterna, L. A.; Hoffman, D. J.; Carr, Thomas


    ETARA is interactive, menu-driven program that performs simulations for analysis of reliability, availability, and maintainability. Written to evaluate performance of electrical power system of Space Station Freedom, but methodology and software applied to any system represented by block diagram. Program written in IBM APL.

  15. An Efficient Method for Reliability-based Multidisciplinary Design Optimization

    Fan Hui; Li Weiji


    Design for modem engineering system is becoming multidisciplinary and incorporates practical uncertainties; therefore, it is necessary to synthesize reliability analysis and the multidiscipLinary design optimization (MDO) techniques for the design of complex engineering system. An advanced first order second moment method-based concurrent subspace optimization approach is proposed based on the comparison and analysis of the existing multidisciplinary optimization techniques and the reliability analysis methods. It is seen through a canard configuration optimization for a three-surface transport that the proposed method is computationally efficient and practical with the least modification to the current deterministic optimization process.

  16. Interactive Reliability-Based Optimal Design

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle; Siemaszko, A.


    Interactive design/optimization of large, complex structural systems is considered. The objective function is assumed to model the expected costs. The constraints are reliability-based and/or related to deterministic code requirements. Solution of this optimization problem is divided in four main...... be used in interactive optimization....

  17. Reliability-Based Optimization of Wind Turbines

    Sørensen, John Dalsgaard; Tarp-Johansen, N.J.


    Reliability-based optimization of the main tower and monopile foundation of an offshore wind turbine is considered. Different formulations are considered of the objective function including benefits and building and failure costs of the wind turbine. Also different reconstruction policies in case...

  18. Reliability analysis of DOOF for Weibull distribution

    陈文华; 崔杰; 樊晓燕; 卢献彪; 相平


    Hierarchical Bayesian method for estimating the failure probability Pi under DOOF by taking the quasi-Beta distribution B(pi-1 , 1,1, b ) as the prior distribution is proposed in this paper. The weighted Least Squares Estimate method was used to obtain the formula for computing reliability distribution parameters and estimating the reliability characteristic values under DOOF. Taking one type of aerospace electrical connectoras an example, the correctness of the above method through statistical analysis of electrical connector acceler-ated life test data was verified.

  19. Reliability based fatigue design and maintenance procedures

    Hanagud, S.


    A stochastic model has been developed to describe a probability for fatigue process by assuming a varying hazard rate. This stochastic model can be used to obtain the desired probability of a crack of certain length at a given location after a certain number of cycles or time. Quantitative estimation of the developed model was also discussed. Application of the model to develop a procedure for reliability-based cost-effective fail-safe structural design is presented. This design procedure includes the reliability improvement due to inspection and repair. Methods of obtaining optimum inspection and maintenance schemes are treated.

  20. Requalification of offshore structures. Reliability analysis of platform

    Bloch, A.; Dalsgaard Soerensen, J. [Aalborg Univ. (Denmark)


    A preliminary reliability analysis has been performed for an example platform. In order to model the structural response such that it is possible to calculate reliability indices, approximate quadratic response surfaces have been determined for cross-sectional forces. Based on a deterministic, code-based analysis the elements and joints which can be expected to be the most critical are selected and response surfaces are established for the cross-sectional forces in those. A stochastic model is established for the uncertain variables. The reliability analysis shows that with this stochastic model the smallest reliability indices for elements are about 3.9. The reliability index for collapse (pushover) is estimated to 6.7 and the reliability index for fatigue failure using a crude model is for the expected most critical detail estimated to 3.2, corresponding to the accumulated damage during the design lifetime of the platform. These reliability indices are considered to be reasonable compared with values recommended by e.g. ISO. The most important stochastic variables are found to be the wave height and the drag coefficient (including the model uncertainty related to estimation of wave forces on the platform). (au)

  1. Equilibrating errors: reliable estimation of information transmission rates in biological systems with spectral analysis-based methods.

    Ignatova, Irina; French, Andrew S; Immonen, Esa-Ville; Frolov, Roman; Weckström, Matti


    Shannon's seminal approach to estimating information capacity is widely used to quantify information processing by biological systems. However, the Shannon information theory, which is based on power spectrum estimation, necessarily contains two sources of error: time delay bias error and random error. These errors are particularly important for systems with relatively large time delay values and for responses of limited duration, as is often the case in experimental work. The window function type and size chosen, as well as the values of inherent delays cause changes in both the delay bias and random errors, with possibly strong effect on the estimates of system properties. Here, we investigated the properties of these errors using white-noise simulations and analysis of experimental photoreceptor responses to naturalistic and white-noise light contrasts. Photoreceptors were used from several insect species, each characterized by different visual performance, behavior, and ecology. We show that the effect of random error on the spectral estimates of photoreceptor performance (gain, coherence, signal-to-noise ratio, Shannon information rate) is opposite to that of the time delay bias error: the former overestimates information rate, while the latter underestimates it. We propose a new algorithm for reducing the impact of time delay bias error and random error, based on discovering, and then using that size of window, at which the absolute values of these errors are equal and opposite, thus cancelling each other, allowing minimally biased measurement of neural coding.

  2. Bypassing BDD Construction for Reliability Analysis

    Williams, Poul Frederick; Nikolskaia, Macha; Rauzy, Antoine


    In this note, we propose a Boolean Expression Diagram (BED)-based algorithm to compute the minimal p-cuts of boolean reliability models such as fault trees. BEDs make it possible to bypass the Binary Decision Diagram (BDD) construction, which is the main cost of fault tree assessment....



    Collaborative filtering recommender systems often suffer from the "Matchmaker" problem, which comes from the false assumption that users are counted only based on their similarity, and high similarity means good advisers. In order to find good advisers for every user, a matchmaker's reliability mode based on the algorithm deriving from Hits is constructed, and it is applied in the proposed World Wide Web (WWW)collaborative recommendation system. Comparative experimental results also show that our approach obviously improves the substantial performance.

  4. A Reliability Based Model for Wind Turbine Selection

    A.K. Rajeevan


    Full Text Available A wind turbine generator output at a specific site depends on many factors, particularly cut- in, rated and cut-out wind speed parameters. Hence power output varies from turbine to turbine. The objective of this paper is to develop a mathematical relationship between reliability and wind power generation. The analytical computation of monthly wind power is obtained from weibull statistical model using cubic mean cube root of wind speed. Reliability calculation is based on failure probability analysis. There are many different types of wind turbinescommercially available in the market. From reliability point of view, to get optimum reliability in power generation, it is desirable to select a wind turbine generator which is best suited for a site. The mathematical relationship developed in this paper can be used for site-matching turbine selection in reliability point of view.

  5. Reliability-Based Design Optimization Considering Variable Uncertainty

    Lim, Woochul; Jang, Junyoung; Lee, Tae Hee [Hanyang University, Seoul (Korea, Republic of); Kim, Jungho; Na, Jongho; Lee, Changkun; Kim, Yongsuk [GM Korea, Incheon (Korea, Republic of)


    Although many reliability analysis and reliability-based design optimization (RBDO) methods have been developed to estimate system reliability, many studies assume the uncertainty of the design variable to be constant. In practice, because uncertainty varies with the design variable's value, this assumption results in inaccurate conclusions about the reliability of the optimum design. Therefore, uncertainty should be considered variable in RBDO. In this paper, we propose an RBDO method considering variable uncertainty. Variable uncertainty can modify uncertainty for each design point, resulting in accurate reliability estimation. Finally, a notable optimum design is obtained using the proposed method with variable uncertainty. A mathematical example and an engine cradle design are illustrated to verify the proposed method.

  6. Human reliability analysis of control room operators

    Santos, Isaac J.A.L.; Carvalho, Paulo Victor R.; Grecco, Claudio H.S. [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)


    Human reliability is the probability that a person correctly performs some system required action in a required time period and performs no extraneous action that can degrade the system Human reliability analysis (HRA) is the analysis, prediction and evaluation of work-oriented human performance using some indices as human error likelihood and probability of task accomplishment. Significant progress has been made in the HRA field during the last years, mainly in nuclear area. Some first-generation HRA methods were developed, as THERP (Technique for human error rate prediction). Now, an array of called second-generation methods are emerging as alternatives, for instance ATHEANA (A Technique for human event analysis). The ergonomics approach has as tool the ergonomic work analysis. It focus on the study of operator's activities in physical and mental form, considering at the same time the observed characteristics of operator and the elements of the work environment as they are presented to and perceived by the operators. The aim of this paper is to propose a methodology to analyze the human reliability of the operators of industrial plant control room, using a framework that includes the approach used by ATHEANA, THERP and the work ergonomics analysis. (author)

  7. Developing safety performance functions incorporating reliability-based risk measures.

    Ibrahim, Shewkar El-Bassiouni; Sayed, Tarek


    Current geometric design guides provide deterministic standards where the safety margin of the design output is generally unknown and there is little knowledge of the safety implications of deviating from these standards. Several studies have advocated probabilistic geometric design where reliability analysis can be used to account for the uncertainty in the design parameters and to provide a risk measure of the implication of deviation from design standards. However, there is currently no link between measures of design reliability and the quantification of safety using collision frequency. The analysis presented in this paper attempts to bridge this gap by incorporating a reliability-based quantitative risk measure such as the probability of non-compliance (P(nc)) in safety performance functions (SPFs). Establishing this link will allow admitting reliability-based design into traditional benefit-cost analysis and should lead to a wider application of the reliability technique in road design. The present application is concerned with the design of horizontal curves, where the limit state function is defined in terms of the available (supply) and stopping (demand) sight distances. A comprehensive collision and geometric design database of two-lane rural highways is used to investigate the effect of the probability of non-compliance on safety. The reliability analysis was carried out using the First Order Reliability Method (FORM). Two Negative Binomial (NB) SPFs were developed to compare models with and without the reliability-based risk measures. It was found that models incorporating the P(nc) provided a better fit to the data set than the traditional (without risk) NB SPFs for total, injury and fatality (I+F) and property damage only (PDO) collisions.

  8. Pushover-based seismic reliability analysis of structures%基于 pushover 方法的结构抗震可靠度分析

    贡金鑫; 于忠翰; 张勤


    To evaluate the seismic performance of the frame structure system from the probability point of view , a method for pushover-based seismic reliability analysis of the structure is proposed based on the secondary develop -ment of the software SAP 2000.Reliability analysis is executed using the FORTRAN program , and pushover analysis is carried out by the software SAP 2000 .Throughout the process of the analysis , the capacity spectrum method ( CSM) for calculating target displacement of structure and the secondary development of SAP 2000 are integrated into the computing of reliability index .The connection between FORTRAN and SAP 2000 is established through component object model (COM) technology, and plenty of public API codes provided by SAP 2000 are compiled to call intrinsic functions of this software .Then, the pushover analysis based on SAP 2000 is introduced to the iteration calculation of reliability analysis , and the uncertainty of the structure is considered by treating the structure parame-ters as random variables during the solution iteration .A numerical example result indicates that the proposed method is practical and efficient in predicting the seismic reliability of the structural system .%为了从概率角度分析框架结构体系的抗震性能,通过对SAP2000软件的二次开发,建立了基于pushover方法的框架结构抗震可靠度分析方法。其中可靠度通过FORTRAN语言编程计算,pushover分析通过SAP2000软件完成。整个分析过程涉及了结构可靠指标的计算、能力谱法( CSM)位移计算和SAP2000软件的二次开发。利用COM技术使FORTRAN程序和SAP2000软件建立联接,同时通过编译SAP2000软件提供的大量公开的API代码调用该软件固有的基本功能,最终使SAP2000的pushover分析过程参与到可靠度迭代计算中。在每次迭代过程中,作为随机变量的结构参数不断变化,以考虑结构自身的不确定性。算例分析结果表明

  9. Reliability Analysis of Fatigue Fracture of Wind Turbine Drivetrain Components

    Berzonskis, Arvydas; Sørensen, John Dalsgaard


    in the volume of the casted ductile iron main shaft, on the reliability of the component. The probabilistic reliability analysis conducted is based on fracture mechanics models. Additionally, the utilization of the probabilistic reliability for operation and maintenance planning and quality control is discussed....... of operation and maintenance. The manufacturing of casted drivetrain components, like the main shaft of the wind turbine, commonly result in many smaller defects through the volume of the component with sizes that depend on the manufacturing method. This paper considers the effect of the initial defect present...

  10. Bridging Resilience Engineering and Human Reliability Analysis

    Ronald L. Boring


    There has been strong interest in the new and emerging field called resilience engineering. This field has been quick to align itself with many existing safety disciplines, but it has also distanced itself from the field of human reliability analysis. To date, the discussion has been somewhat one-sided, with much discussion about the new insights afforded by resilience engineering. This paper presents an attempt to address resilience engineering from the perspective of human reliability analysis (HRA). It is argued that HRA shares much in common with resilience engineering and that, in fact, it can help strengthen nascent ideas in resilience engineering. This paper seeks to clarify and ultimately refute the arguments that have served to divide HRA and resilience engineering.

  11. Coverage Modeling and Reliability Analysis Using Multi-state Function


    Fault tree analysis is an effective method for predicting the reliability of a system. It gives a pictorial representation and logical framework for analyzing the reliability. Also, it has been used for a long time as an effective method for the quantitative and qualitative analysis of the failure modes of critical systems. In this paper, we propose a new general coverage model (GCM) based on hardware independent faults. Using this model, an effective software tool can be constructed to detect, locate and recover fault from the faulty system. This model can be applied to identify the key component that can cause the failure of the system using failure mode effect analysis (FMEA).




    Full Text Available The veracity and secrecy of medical information which is transacted over the Internet is vulnerable to attack. But the transaction of such details is mandatory in order to avail the luxury of medical services anywhere, anytime. Especially in a web service enabled system for hospital management, it becomes necessary to address these security issues. It is mandatory that the services guarantee message delivery to software applications, with a chosen level of quality of service (QoS. This paper presents a VDM++ based specification for modelling a security framework for web services with non repudiation to ensure that a party in a dispute cannot repudiate, or refute the validity of a statement or contract and it is ensured that the transaction happens in a reliable manner. This model presents the procedure and technical options to have a secure communication over Internet with web services. Based on the model the Medi - Helper is developed to use the technologies of WS-Security, WS-Reliability and WS-Policy, WSRN in order to create encrypted messages so that the Patient’s medical records are not tampered with when relayed over Internet, and are sent in a reliable manner. In addition to authentication, integrity, confidentiality, as proposed in this paper security framework for healthcare based web services is equipped with non repudiation which is not inclusive in many existing frameworks.

  13. Proof-of-Concept Demonstrations for Computation-Based Human Reliability Analysis. Modeling Operator Performance During Flooding Scenarios

    Joe, Jeffrey Clark [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boring, Ronald Laurids [Idaho National Lab. (INL), Idaho Falls, ID (United States); Herberger, Sarah Elizabeth Marie [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis Lee [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    The United States (U.S.) Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) program has the overall objective to help sustain the existing commercial nuclear power plants (NPPs). To accomplish this program objective, there are multiple LWRS “pathways,” or research and development (R&D) focus areas. One LWRS focus area is called the Risk-Informed Safety Margin and Characterization (RISMC) pathway. Initial efforts under this pathway to combine probabilistic and plant multi-physics models to quantify safety margins and support business decisions also included HRA, but in a somewhat simplified manner. HRA experts at Idaho National Laboratory (INL) have been collaborating with other experts to develop a computational HRA approach, called the Human Unimodel for Nuclear Technology to Enhance Reliability (HUNTER), for inclusion into the RISMC framework. The basic premise of this research is to leverage applicable computational techniques, namely simulation and modeling, to develop and then, using RAVEN as a controller, seamlessly integrate virtual operator models (HUNTER) with 1) the dynamic computational MOOSE runtime environment that includes a full-scope plant model, and 2) the RISMC framework PRA models already in use. The HUNTER computational HRA approach is a hybrid approach that leverages past work from cognitive psychology, human performance modeling, and HRA, but it is also a significant departure from existing static and even dynamic HRA methods. This report is divided into five chapters that cover the development of an external flooding event test case and associated statistical modeling considerations.

  14. A Passive System Reliability Analysis for a Station Blackout

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


    The latest iterations of advanced reactor designs have included increased reliance on passive safety systems to maintain plant integrity during unplanned sequences. While these systems are advantageous in reducing the reliance on human intervention and availability of power, the phenomenological foundations on which these systems are built require a novel approach to a reliability assessment. Passive systems possess the unique ability to fail functionally without failing physically, a result of their explicit dependency on existing boundary conditions that drive their operating mode and capacity. Argonne National Laboratory is performing ongoing analyses that demonstrate various methodologies for the characterization of passive system reliability within a probabilistic framework. Two reliability analysis techniques are utilized in this work. The first approach, the Reliability Method for Passive Systems, provides a mechanistic technique employing deterministic models and conventional static event trees. The second approach, a simulation-based technique, utilizes discrete dynamic event trees to treat time- dependent phenomena during scenario evolution. For this demonstration analysis, both reliability assessment techniques are used to analyze an extended station blackout in a pool-type sodium fast reactor (SFR) coupled with a reactor cavity cooling system (RCCS). This work demonstrates the entire process of a passive system reliability analysis, including identification of important parameters and failure metrics, treatment of uncertainties and analysis of results.

  15. Representative Sampling for reliable data analysis

    Petersen, Lars; Esbensen, Kim Harry


    regime in order to secure the necessary reliability of: samples (which must be representative, from the primary sampling onwards), analysis (which will not mean anything outside the miniscule analytical volume without representativity ruling all mass reductions involved, also in the laboratory) and data...... analysis (“data” do not exist in isolation of their provenance). The Total Sampling Error (TSE) is by far the dominating contribution to all analytical endeavours, often 100+ times larger than the Total Analytical Error (TAE).We present a summarizing set of only seven Sampling Unit Operations (SUOs...

  16. Lifeline system network reliability calculation based on GIS and FTA

    TANG Ai-ping; OU Jin-ping; LU Qin-nian; ZHANG Ke-xu


    Lifelines, such as pipeline, transportation, communication, electric transmission and medical rescue systems, are complicated networks that always distribute spatially over large geological and geographic units.The quantification of their reliability under an earthquake occurrence should be highly regarded, because the performance of these systems during a destructive earthquake is vital in order to estimate direct and indirect economic losses from lifeline failures, and is also related to laying out a rescue plan. The research in this paper aims to develop a new earthquake reliability calculation methodology for lifeline systems. The methodology of the network reliability for lifeline systems is based on fault tree analysis (FTA) and geological information system(GIS). The interactions existing in a lifeline system are considered herein. The lifeline systems are idealized as equivalent networks, consisting of nodes and links, and are described by network analysis in GIS. Firstly, the node is divided into two types: simple node and complicated node, where the reliability of the complicated node is calculated by FTA and interaction is regarded as one factor to affect performance of the nodes. The reliability of simple node and link is evaluated by code. Then, the reliability of the entire network is assessed based on GIS and FTA. Lastly, an illustration is given to show the methodology.

  17. Multi-mode reliability-based design of horizontal curves.

    Essa, Mohamed; Sayed, Tarek; Hussein, Mohamed


    Recently, reliability analysis has been advocated as an effective approach to account for uncertainty in the geometric design process and to evaluate the risk associated with a particular design. In this approach, a risk measure (e.g. probability of noncompliance) is calculated to represent the probability that a specific design would not meet standard requirements. The majority of previous applications of reliability analysis in geometric design focused on evaluating the probability of noncompliance for only one mode of noncompliance such as insufficient sight distance. However, in many design situations, more than one mode of noncompliance may be present (e.g. insufficient sight distance and vehicle skidding at horizontal curves). In these situations, utilizing a multi-mode reliability approach that considers more than one failure (noncompliance) mode is required. The main objective of this paper is to demonstrate the application of multi-mode (system) reliability analysis to the design of horizontal curves. The process is demonstrated by a case study of Sea-to-Sky Highway located between Vancouver and Whistler, in southern British Columbia, Canada. Two noncompliance modes were considered: insufficient sight distance and vehicle skidding. The results show the importance of accounting for several noncompliance modes in the reliability model. The system reliability concept could be used in future studies to calibrate the design of various design elements in order to achieve consistent safety levels based on all possible modes of noncompliance.

  18. Reliability of photographic posture analysis of adolescents.

    Hazar, Zeynep; Karabicak, Gul Oznur; Tiftikci, Ugur


    [Purpose] Postural problems of adolescents needs to be evaluated accurately because they may lead to greater problems in the musculoskeletal system as they develop. Although photographic posture analysis has been frequently used, more simple and accessible methods are still needed. The purpose of this study was to investigate the inter- and intra-rater reliability of photographic posture analysis using MB-ruler software. [Subjects and Methods] Subjects were 30 adolescents (15 girls and 15 boys, mean age: 16.4±0.4 years, mean height 166.3±6.7 cm, mean weight 63.8±15.1 kg) and photographs of their habitual standing posture photographs were taken in the sagittal plane. For the evaluation of postural angles, reflective markers were placed on anatomical landmarks. For angular measurements, MB-ruler (Markus Bader- MB Software Solutions, triangular screen ruler) was used. Photographic evaluations were performed by two observers with a repetition after a week. Test-retest and inter-rater reliability evaluations were calculated using intra-class correlation coefficients (ICC). [Results] Inter-rater (ICC>0.972) and test-retest (ICC>0.774) reliability were found to be in the range of acceptable to excellent. [Conclusion] Reference angles for postural evaluation were found to be reliable and repeatable. The present method was found to be an easy and non-invasive method and it may be utilized by researchers who are in search of an alternative method for photographic postural assessments.

  19. Method for software reliability assessment based on fuzzy fault tree analysis%软件可靠度的模糊故障树评定方法

    刘博宁; 张鹏; 张建业; 马秋芝


    软件可靠性的定量评价是软件可靠性工程的关键问题之一,采用故障树方法对软件进行定性和定量分析,提出了两类情况下对影响软件可靠性的主次因素划分及其模糊权重的计算方法.在此基础上,建立多级模糊评价模型,提出了增广和聚合算法,并给出了软件可靠度算式.选择某型航空装备软件进行了测试实例分析,实验结果表明了该方法评价结构的合理性与评价算法的有效性,适用于软件质量及开发过程控制的工程实践.%The quantitative assessment of software reliability is one of the most important problem for software reliability project, this paper used firstly the qualitative and quantitative analyzing based on fault tree analysis of software, it proposed the method for fuzzy weight calculating and the primary and secondary ingredients compartmentalizing. It established the multi-grade fuzzy assessment model, discussed the enhanced and converging arithmetic, and proposed the expressions of reliability. This method presented its rationality of assessment configuration and validity of assessment arithmetic through testing and analyzing of an aero equipment' s software, it could be used on quality and exploitation control engineering for software.

  20. Integration of Human Reliability Analysis Models into the Simulation-Based Framework for the Risk-Informed Safety Margin Characterization Toolkit

    Boring, Ronald [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rasmussen, Martin [Norwegian Univ. of Science and Technology, Trondheim (Norway). Social Research; Herberger, Sarah [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ulrich, Thomas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Groth, Katrina [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Curtis [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    This report presents an application of a computation-based human reliability analysis (HRA) framework called the Human Unimodel for Nuclear Technology to Enhance Reliability (HUNTER). HUNTER has been developed not as a standalone HRA method but rather as framework that ties together different HRA methods to model dynamic risk of human activities as part of an overall probabilistic risk assessment (PRA). While we have adopted particular methods to build an initial model, the HUNTER framework is meant to be intrinsically flexible to new pieces that achieve particular modeling goals. In the present report, the HUNTER implementation has the following goals: • Integration with a high fidelity thermal-hydraulic model capable of modeling nuclear power plant behaviors and transients • Consideration of a PRA context • Incorporation of a solid psychological basis for operator performance • Demonstration of a functional dynamic model of a plant upset condition and appropriate operator response This report outlines these efforts and presents the case study of a station blackout scenario to demonstrate the various modules developed to date under the HUNTER research umbrella.

  1. An index-based short-form of the WISC-IV with accompanying analysis of the reliability and abnormality of differences.

    Crawford, John R; Anderson, Vicki; Rankin, Peter M; MacDonald, Jayne


    To develop an Index-based, seven subtest, short-form of the Wechsler intelligence scale for children fourth edition (WISC-IV) that offers the same comprehensive range of analytic methods available for the full-length version. Psychometric. The short-form Indexes had high reliability and criterion validity. Scores are expressed as Index scores and as percentiles. Methods are provided that allow setting of confidence limits on scores, and analysis of the reliability and abnormality of Index score differences. The use of the short-form is illustrated with a case example. A computer programme (that automates scoring and implements all the analytical methods) accompanies this paper and can be downloaded from the following web address: The short-form will be useful when pressure of time or client fatigue precludes use of a full-length WISC-IV. The accompanying computer programme scores and analyses an individual's performance on the short-form instantaneously and minimizes the chance of clerical error.

  2. Reliability Analysis Based on a Jump Diffusion Model with Two Wiener Processes for Cloud Computing with Big Data

    Yoshinobu Tamura


    Full Text Available At present, many cloud services are managed by using open source software, such as OpenStack and Eucalyptus, because of the unification management of data, cost reduction, quick delivery and work savings. The operation phase of cloud computing has a unique feature, such as the provisioning processes, the network-based operation and the diversity of data, because the operation phase of cloud computing changes depending on many external factors. We propose a jump diffusion model with two-dimensional Wiener processes in order to consider the interesting aspects of the network traffic and big data on cloud computing. In particular, we assess the stability of cloud software by using the sample paths obtained from the jump diffusion model with two-dimensional Wiener processes. Moreover, we discuss the optimal maintenance problem based on the proposed jump diffusion model. Furthermore, we analyze actual data to show numerical examples of dependability optimization based on the software maintenance cost considering big data on cloud computing.

  3. Reliability analysis and initial requirements for FC systems and stacks

    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.

  4. Representative Sampling for reliable data analysis

    Petersen, Lars; Esbensen, Kim Harry


    The Theory of Sampling (TOS) provides a description of all errors involved in sampling of heterogeneous materials as well as all necessary tools for their evaluation, elimination and/or minimization. This tutorial elaborates on—and illustrates—selected central aspects of TOS. The theoretical...... regime in order to secure the necessary reliability of: samples (which must be representative, from the primary sampling onwards), analysis (which will not mean anything outside the miniscule analytical volume without representativity ruling all mass reductions involved, also in the laboratory) and data...

  5. Structural hybrid reliability index and its convergent solving method based on random–fuzzy–interval reliability model

    Hai An


    Full Text Available Aiming to resolve the problems of a variety of uncertainty variables that coexist in the engineering structure reliability analysis, a new hybrid reliability index to evaluate structural hybrid reliability, based on the random–fuzzy–interval model, is proposed in this article. The convergent solving method is also presented. First, the truncated probability reliability model, the fuzzy random reliability model, and the non-probabilistic interval reliability model are introduced. Then, the new hybrid reliability index definition is presented based on the random–fuzzy–interval model. Furthermore, the calculation flowchart of the hybrid reliability index is presented and it is solved using the modified limit-step length iterative algorithm, which ensures convergence. And the validity of convergent algorithm for the hybrid reliability model is verified through the calculation examples in literature. In the end, a numerical example is demonstrated to show that the hybrid reliability index is applicable for the wear reliability assessment of mechanisms, where truncated random variables, fuzzy random variables, and interval variables coexist. The demonstration also shows the good convergence of the iterative algorithm proposed in this article.

  6. Reliability of the Emergency Severity Index: Meta-analysis

    Amir Mirhaghi


    Full Text Available Objectives: Although triage systems based on the Emergency Severity Index (ESI have many advantages in terms of simplicity and clarity, previous research has questioned their reliability in practice. Therefore, the aim of this meta-analysis was to determine the reliability of ESI triage scales. Methods: This metaanalysis was performed in March 2014. Electronic research databases were searched and articles conforming to the Guidelines for Reporting Reliability and Agreement Studies were selected. Two researchers independently examined selected abstracts. Data were extracted in the following categories: version of scale (latest/older, participants (adult/paediatric, raters (nurse, physician or expert, method of reliability (intra/inter-rater, reliability statistics (weighted/unweighted kappa and the origin and publication year of the study. The effect size was obtained by the Z-transformation of reliability coefficients. Data were pooled with random-effects models and a meta-regression was performed based on the method of moments estimator. Results: A total of 19 studies from six countries were included in the analysis. The pooled coefficient for the ESI triage scales was substantial at 0.791 (95% confidence interval: 0.787‒0.795. Agreement was higher with the latest and adult versions of the scale and among expert raters, compared to agreement with older and paediatric versions of the scales and with other groups of raters, respectively. Conclusion: ESI triage scales showed an acceptable level of overall reliability. However, ESI scales require more development in order to see full agreement from all rater groups. Further studies concentrating on other aspects of reliability assessment are needed.

  7. Reliability analysis method and the application based on ANSYS%基于ANSYS的可靠度分析方法及应用

    杨超; 高谦; 钟海滨


    Through the over view on reliability analysis as a modern engineering analysis, it was known that there are many factors, such as material properties, processing tolerance, boundary conditions and loading, etc, can make analysis not accuracy. Design and analysis of structure engineering contains many uncertainty, engineering of the factors of uncertainty and random characteristics description is the basis of reliability analysis. Structure reliability evaluation of the reliability of the structure is index. The probability analysis is that our analysis the model on some of the input parameters and uncertainty on the assumption of the influence on the result of the analysis, and the results can be judged, it can improve product quality and reliability when it cant completely eliminate input parameter uncertainty. The software of FEA (Finite Element Analysis) ANSYS provides the function of probabilistic design of PDS, which makes structural probabilistic analysis very easy. According to the structural failure mode to determine the structure and function, thereby a structure limit state equation can be set up, again with the structure reliability analysis of the Monte Carlo method (MCS method) , structure failure frequency can be used to estimate the failure probability. In this paper, the technique of the structural reliability analysis through the probabilistic design of ANSYS was presented. From an instance, it showed that the method presented is feasible.%通过对可靠度分析的概述理解到现代工程分析中实体模型不确定因素众多,进而带来分析的不准确性.基于有限元分析软件ANSYS提供的概率设计系统(PDS)的概率分析功能,使对结构的概率分析非常容易.根据结构的失效模式来确定结构功能函数,由此建立结构极限状态方程,再运用结构可靠度分析中的蒙特卡洛法(MCS法)利用结构的失效频率来估算其失效概率.在本文中提出了利用ANSYS的概率分析功能结

  8. Advancing Usability Evaluation through Human Reliability Analysis

    Ronald L. Boring; David I. Gertman


    This paper introduces a novel augmentation to the current heuristic usability evaluation methodology. The SPAR-H human reliability analysis method was developed for categorizing human performance in nuclear power plants. Despite the specialized use of SPAR-H for safety critical scenarios, the method also holds promise for use in commercial off-the-shelf software usability evaluations. The SPAR-H method shares task analysis underpinnings with human-computer interaction, and it can be easily adapted to incorporate usability heuristics as performance shaping factors. By assigning probabilistic modifiers to heuristics, it is possible to arrive at the usability error probability (UEP). This UEP is not a literal probability of error but nonetheless provides a quantitative basis to heuristic evaluation. When combined with a consequence matrix for usability errors, this method affords ready prioritization of usability issues.

  9. Reliability Analysis of Screw Mounting Location Based on ANSYS%基于ANSYS丝杠安装位置的可靠性分析



    Based on ANSYS software analysis platform and static theoretical analysis technology and with, finite element analysis as core, this paer uses Pro / E to build the model and imports ANSYS for analysis. Both softwars are used to do the reliability analysis and study of the screw mounting position of the machine bed. lts deformation, stress, strain and other physical quantities are ana-lyzed and discussed. Comparing the difference before and after its optimization, the structure optimization strategy is proposed, which is used to optimize the product structure design and speed up the design process.%基于ANSYS软件分析平台,以静力学理论分析技术为基础,以有限元分析方法为核心,利用Pro/E的三维建模功能建立工件模型后,导入ANSYS软件进行了分析。并联合使用这两款软件对某机床床身的丝杠安装位置进行了零件的可靠性分析与研究,对变形、应力、应变等物理量进行了分析讨论。在对优化前后之间的差异进行了比较分析后提出了结构优化策略。优化了产品设计结构并加快了设计过程。

  10. Operation safety of complex industrial systems. Forward-looking analysis and reliability databases; Surete de fonctionnement des systemes industriels complexes. Analyse previsionnelle et bases de donnees de fiabilite

    Zwingelstein, G


    The forward-looking analysis of systems failure consists in identifying the conditions that may lead to failures and to foresee their consequences on the reliability, maintainability, availability and safety of systems at the design stage or at the operation stage. It is performed from various information, the selection and analysis of which allows to design a system model. The essential information is: a description of the real system (physical and functional structures), the characteristics of the system components and of the interactions between them (failure modes and their consequences), the relations between the system and its environment, and the consideration of human errors at the exploitation step. Content: 1 - steps of an operation safety analysis; 2 - functional analysis methods: FAST, RELIASEP, SADT, IDEFO, APTE and other methods; 3 - Forward-looking analysis methods: qualitative methods, mixed and quantitative methods, human factors; 4 - reliability databases. (J.S.)

  11. Reliability Analysis of a Green Roof Under Different Storm Scenarios

    William, R. K.; Stillwell, A. S.


    Urban environments continue to face the challenges of localized flooding and decreased water quality brought on by the increasing amount of impervious area in the built environment. Green infrastructure provides an alternative to conventional storm sewer design by using natural processes to filter and store stormwater at its source. However, there are currently few consistent standards available in North America to ensure that installed green infrastructure is performing as expected. This analysis offers a method for characterizing green roof failure using a visual aid commonly used in earthquake engineering: fragility curves. We adapted the concept of the fragility curve based on the efficiency in runoff reduction provided by a green roof compared to a conventional roof under different storm scenarios. We then used the 2D distributed surface water-groundwater coupled model MIKE SHE to model the impact that a real green roof might have on runoff in different storm events. We then employed a multiple regression analysis to generate an algebraic demand model that was input into the Matlab-based reliability analysis model FERUM, which was then used to calculate the probability of failure. The use of reliability analysis as a part of green infrastructure design code can provide insights into green roof weaknesses and areas for improvement. It also supports the design of code that is more resilient than current standards and is easily testable for failure. Finally, the understanding of reliability of a single green roof module under different scenarios can support holistic testing of system reliability.

  12. Reliability Analysis of Tubular Joints in Offshore Structures

    Thoft-Christensen, Palle; Sørensen, John Dalsgaard


    Reliability analysis of single tubular joints and offshore platforms with tubular joints is" presented. The failure modes considered are yielding, punching, buckling and fatigue failure. Element reliability as well as systems reliability approaches are used and illustrated by several examples....... Finally, optimal design of tubular.joints with reliability constraints is discussed and illustrated by an example....

  13. 基于故障物理的电路板可靠性分析%Reliability Analysis of Circuit Board Based on Physics of Failure

    王文; 范源远; 王成刚; 胡建明; 黄胜利


    在装备生命周期的各阶段,其承受的环境载荷都可能对装备造成累积损伤,进而引发故障。从装备设计特性和寿命期环境应力分布及其相互作用角度来分析装备的故障更符合其未来实际使用情况。介绍了电路板常用的故障物理模型,阐述了基于故障物理的电路板可靠性分析流程,明确了潜在故障仿真思路,为装备早期可靠性设计、测试性设计与评价提供了方法依据。%At every stage of life cycle, environmental loads may cause cumulative damage to the equipment, and then caus-ing fault. It is in accord with the actual usage in the future for equipment to analyze its faults from the angle of the design feature of equipments, longevity environment stress distribution and the interaction between them. The common fault physi-cal models of circuit boards were presented, and the circuit reliability analysis process based on physics-of-failure (PoF) was expounded. The simulation method of potential fault was expatiated. A feasible method was provided for the early eval-uation and design for reliability and testability of equipment.

  14. Software Architecture Reliability Analysis using Failure Scenarios

    Tekinerdogan, B.; Sözer, Hasan; Aksit, Mehmet

    With the increasing size and complexity of software in embedded systems, software has now become a primary threat for the reliability. Several mature conventional reliability engineering techniques exist in literature but traditionally these have primarily addressed failures in hardware components

  15. Classification using least squares support vector machine for reliability analysis

    Zhi-wei GUO; Guang-chen BAI


    In order to improve the efficiency of the support vector machine (SVM) for classification to deal with a large amount of samples,the least squares support vector machine (LSSVM) for classification methods is introduced into the reliability analysis.To reduce the computational cost,the solution of the SVM is transformed from a quadratic programming to a group of linear equations.The numerical results indicate that the reliability method based on the LSSVM for classification has higher accuracy and requires less computational cost than the SVM method.

  16. Application of Reliability Analysis for Optimal Design of Monolithic Vertical Wall Breakwaters

    Burcharth, H. F.; Sørensen, John Dalsgaard; Christiani, E.


    Reliability analysis and reliability-based design of monolithic vertical wall breakwaters are considered. Probabilistic models of some of the most important failure modes are described. The failures are sliding and slip surface failure of a rubble mound and a clay foundation. Relevant design...... variables are identified and a reliability-based design optimization procedure is formulated. Results from an illustrative example are given....

  17. Human Reliability Analysis for Small Modular Reactors

    Ronald L. Boring; David I. Gertman


    Because no human reliability analysis (HRA) method was specifically developed for small modular reactors (SMRs), the application of any current HRA method to SMRs represents tradeoffs. A first- generation HRA method like THERP provides clearly defined activity types, but these activity types do not map to the human-system interface or concept of operations confronting SMR operators. A second- generation HRA method like ATHEANA is flexible enough to be used for SMR applications, but there is currently insufficient guidance for the analyst, requiring considerably more first-of-a-kind analyses and extensive SMR expertise in order to complete a quality HRA. Although no current HRA method is optimized to SMRs, it is possible to use existing HRA methods to identify errors, incorporate them as human failure events in the probabilistic risk assessment (PRA), and quantify them. In this paper, we provided preliminary guidance to assist the human reliability analyst and reviewer in understanding how to apply current HRA methods to the domain of SMRs. While it is possible to perform a satisfactory HRA using existing HRA methods, ultimately it is desirable to formally incorporate SMR considerations into the methods. This may require the development of new HRA methods. More practicably, existing methods need to be adapted to incorporate SMRs. Such adaptations may take the form of guidance on the complex mapping between conventional light water reactors and small modular reactors. While many behaviors and activities are shared between current plants and SMRs, the methods must adapt if they are to perform a valid and accurate analysis of plant personnel performance in SMRs.

  18. Assessment Method for the Reliability of Power Transformer Based on Fault-tree Analysis%基于粒子群优化支持向量机的变压器故障诊断

    费胜巍; 苗玉彬; 刘成良


    Accurate assessment of system reliability with limited or insufficient statistical data is difficult. At present, to assess the reliability of the transformers primarily depend on the statistics data, and the result of the assessment does not accurately reflect the reliability of a transformer. Fault tree is a powerful tool for depicting the logical relationships between the faults system. However, for a sophisticated reliability system, like power transformer,fault analysis is hard or infeasible because of the complexities of the equipment configuration and its faults. This paper presents a method which overcomes the drawbacks of traditional fault-tree analysis (FTA) by using FTA based on fault probability and equivalent calculation of each failure mode. Based on the further analysis of typical failure modes and influences of power transformer, the fault-tree of transformer is set up by using FTA techniques and the assessment method for the reliability of transformer is put forward, combined with the index of the importance and the method of improved analytic hierarchy process(IAHP). The assessment examples show the method can deduct the failure modes of transformer clearly, meanwhile, find out the weaknesses in time during the operation and get better assessment results. The method is helpful for the reliability analysis of a sophisticated system.

  19. Distribution System Reliability Analysis for Smart Grid Applications

    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.

  20. Reliability analysis of retaining walls with multiple failure modes

    张道兵; 孙志彬; 朱川曲


    In order to reduce the errors of the reliability of the retaining wall structure in the establishment of function, in the estimation of parameter and algorithm, firstly, two new reliability and stability models of anti-slipping and anti-overturning based on the upper-bound theory of limit analysis were established, and two kinds of failure modes were regarded as a series of systems with multiple correlated failure modes. Then, statistical characteristics of parameters of the retaining wall structure were inferred by maximal entropy principle. At last, the structural reliabilities of single failure mode and multiple failure modes were calculated by Monte Carlo method in MATLAB and the results were compared and analyzed on the sensitivity. It indicates that this method, with a high precision, is not only easy to program and quick in calculation, but also without the limit of nonlinear functions and non-normal random variables. And the results calculated by this method which applies both the limit analysis theory, maximal entropy principle and Monte Carlo method into analyzing the reliability of the retaining wall structures is more scientific, accurate and reliable, in comparison with those calculated by traditional method.

  1. A reliability measure of protein-protein interactions and a reliability measure-based search engine.

    Park, Byungkyu; Han, Kyungsook


    Many methods developed for estimating the reliability of protein-protein interactions are based on the topology of protein-protein interaction networks. This paper describes a new reliability measure for protein-protein interactions, which does not rely on the topology of protein interaction networks, but expresses biological information on functional roles, sub-cellular localisations and protein classes as a scoring schema. The new measure is useful for filtering many spurious interactions, as well as for estimating the reliability of protein interaction data. In particular, the reliability measure can be used to search protein-protein interactions with the desired reliability in databases. The reliability-based search engine is available at We believe this is the first search engine for interacting proteins, which is made available to public. The search engine and the reliability measure of protein interactions should provide useful information for determining proteins to focus on.

  2. Task Decomposition in Human Reliability Analysis

    Boring, Ronald Laurids [Idaho National Laboratory; Joe, Jeffrey Clark [Idaho National Laboratory


    In the probabilistic safety assessments (PSAs) used in the nuclear industry, human failure events (HFEs) are determined as a subset of hardware failures, namely those hardware failures that could be triggered by human action or inaction. This approach is top-down, starting with hardware faults and deducing human contributions to those faults. Elsewhere, more traditionally human factors driven approaches would tend to look at opportunities for human errors first in a task analysis and then identify which of those errors is risk significant. The intersection of top-down and bottom-up approaches to defining HFEs has not been carefully studied. Ideally, both approaches should arrive at the same set of HFEs. This question remains central as human reliability analysis (HRA) methods are generalized to new domains like oil and gas. The HFEs used in nuclear PSAs tend to be top-down— defined as a subset of the PSA—whereas the HFEs used in petroleum quantitative risk assessments (QRAs) are more likely to be bottom-up—derived from a task analysis conducted by human factors experts. The marriage of these approaches is necessary in order to ensure that HRA methods developed for top-down HFEs are also sufficient for bottom-up applications.

  3. Reliability-based assessment of polyethylene pipe creep lifetime

    Khelif, Rabia [LaMI-UBP and IFMA, Campus de Clermont-Fd, Les Cezeaux, BP 265, 63175 Aubiere Cedex (France); LR3MI, Departement de Genie Mecanique, Universite Badji Mokhtar, BP 12, Annaba 23000 (Algeria)], E-mail:; Chateauneuf, Alaa [LGC-University Blaise Pascal, Campus des Cezeaux, BP 206, 63174 Aubiere Cedex (France)], E-mail:; Chaoui, Kamel [LR3MI, Departement de Genie Mecanique, Universite Badji Mokhtar, BP 12, Annaba 23000 (Algeria)], E-mail:


    Lifetime management of underground pipelines is mandatory for safe hydrocarbon transmission and distribution systems. The use of high-density polyethylene tubes subjected to internal pressure, external loading and environmental variations requires a reliability study in order to define the service limits and the optimal operating conditions. In service, the time-dependent phenomena, especially creep, take place during the pipe lifetime, leading to significant strength reduction. In this work, the reliability-based assessment of pipe lifetime models is carried out, in order to propose a probabilistic methodology for lifetime model selection and to determine the pipe safety levels as well as the most important parameters for pipeline reliability. This study is enhanced by parametric analysis on pipe configuration, gas pressure and operating temperature.

  4. Spanning Trees and bootstrap reliability estimation in correlation based networks

    Tumminello, M; Lillo, F; Micciché, S; Mantegna, R N


    We introduce a new technique to associate a spanning tree to the average linkage cluster analysis. We term this tree as the Average Linkage Minimum Spanning Tree. We also introduce a technique to associate a value of reliability to links of correlation based graphs by using bootstrap replicas of data. Both techniques are applied to the portfolio of the 300 most capitalized stocks traded at New York Stock Exchange during the time period 2001-2003. We show that the Average Linkage Minimum Spanning Tree recognizes economic sectors and sub-sectors as communities in the network slightly better than the Minimum Spanning Tree does. We also show that the average reliability of links in the Minimum Spanning Tree is slightly greater than the average reliability of links in the Average Linkage Minimum Spanning Tree.

  5. Reliability and maintainability analysis of electrical system of drum shearers

    SEYED Hadi Hoseinie; MOHAMMAD Ataei; REZA Khalokakaie; UDAY Kumar


    The reliability and maintainability of electrical system of drum shearer at Parvade.l Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. According to trend and serial correlation tests, the data were independent and identically distributed (iid) and therefore the statistical techniques were used for modeling. The data analysis show that the time between failures (TBF) and time to repair (TTR) data obey the lognormal and Weibull 3 parameters distribution respectively. Reliability-based preventive maintenance time intervals for electrical system of the drum shearer were calculated with regard to reliability plot. The reliability-based maintenance intervals for 90%, 80%, 70% and 50% reliability level are respectively 9.91, 17.96, 27.56 and 56.1 h. Also the calculations show that time to repair (TTR) of this system varies in range 0.17-4 h with 1.002 h as mean time to repair (MTTR). There is a 80% chance that the electrical system of shearer of Parvade.l mine repair will be accomplished within 1.45 h.

  6. Optimal Reliability-Based Code Calibration

    Sørensen, John Dalsgaard; Kroon, I. B.; Faber, M. H.


    Calibration of partial safety factors is considered in general, including classes of structures where no code exists beforehand. The partial safety factors are determined such that the difference between the reliability for the different structures in the class considered and a target reliability...... level is minimized. Code calibration on a decision theoretical basis is also considered and it is shown how target reliability indices can be calibrated. Results from code calibration for rubble mound breakwater designs are shown....

  7. Reliability Analysis of Free Jet Scour Below Dams

    Chuanqi Li


    Full Text Available Current formulas for calculating scour depth below of a free over fall are mostly deterministic in nature and do not adequately consider the uncertainties of various scouring parameters. A reliability-based assessment of scour, taking into account uncertainties of parameters and coefficients involved, should be performed. This paper studies the reliability of a dam foundation under the threat of scour. A model for calculating the reliability of scour and estimating the probability of failure of the dam foundation subjected to scour is presented. The Maximum Entropy Method is applied to construct the probability density function (PDF of the performance function subject to the moment constraints. Monte Carlo simulation (MCS is applied for uncertainty analysis. An example is considered, and there liability of its scour is computed, the influence of various random variables on the probability failure is analyzed.

  8. Sensitivity Analysis for the System Reliability Function


    reliabilities. The unique feature of the approach is that stunple data collected on K inde-ndent replications using a specified component reliability % v &:•r...Carlo method. The polynomial time algorithm of Agrawaw Pad Satyanarayana (104) fIr the exact reliability computaton for seres- allel systems exemplifies...consideration. As an example for the s-t connectedness problem, let denote -7- edge-disjoint minimal s-t paths of G and let V , denote edge-disjoint

  9. Reliability Based Optimization of Structural Systems

    Sørensen, John Dalsgaard


    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...

  10. Strength Reliability Analysis of Turbine Blade Using Surrogate Models

    Wei Duan


    Full Text Available There are many stochastic parameters that have an effect on the reliability of steam turbine blades performance in practical operation. In order to improve the reliability of blade design, it is necessary to take these stochastic parameters into account. In this study, a variable cross-section twisted blade is investigated and geometrical parameters, material parameters and load parameters are considered as random variables. A reliability analysis method as a combination of a Finite Element Method (FEM, a surrogate model and Monte Carlo Simulation (MCS, is applied to solve the blade reliability analysis. Based on the blade finite element parametrical model and the experimental design, two kinds of surrogate models, Polynomial Response Surface (PRS and Artificial Neural Network (ANN, are applied to construct the approximation analytical expressions between the blade responses (including maximum stress and deflection and random input variables, which act as a surrogate of finite element solver to drastically reduce the number of simulations required. Then the surrogate is used for most of the samples needed in the Monte Carlo method and the statistical parameters and cumulative distribution functions of the maximum stress and deflection are obtained by Monte Carlo simulation. Finally, the probabilistic sensitivities analysis, which combines the magnitude of the gradient and the width of the scatter range of the random input variables, is applied to evaluate how much the maximum stress and deflection of the blade are influenced by the random nature of input parameters.


    彭世济; 卢明银; 张达贤


    It is stipulated in the China national document, named"The Economical Appraisal Methods for Construction Projects" that dynamic analysis should dominate the project economical appraisal methods.This paper has set up a dynamic investment forecast model for Yuanbaoshan Surface Coal Mine. Based on this model, the investment reliability using simulation and analytic methods has been analysed, anti the probability that the designed internal rate of return can reach 8.4%, from economic points of view, have been also studied.

  12. Reliability in Cross-National Content Analysis.

    Peter, Jochen; Lauf, Edmund


    Investigates how coder characteristics such as language skills, political knowledge, coding experience, and coding certainty affected inter-coder and coder-training reliability. Shows that language skills influenced both reliability types. Suggests that cross-national researchers should pay more attention to cross-national assessments of…

  13. Software architecture reliability analysis using failure scenarios

    Tekinerdogan, Bedir; Sozer, Hasan; Aksit, Mehmet


    With the increasing size and complexity of software in embedded systems, software has now become a primary threat for the reliability. Several mature conventional reliability engineering techniques exist in literature but traditionally these have primarily addressed failures in hardware components a

  14. Software reliability experiments data analysis and investigation

    Walker, J. Leslie; Caglayan, Alper K.


    The objectives are to investigate the fundamental reasons which cause independently developed software programs to fail dependently, and to examine fault tolerant software structures which maximize reliability gain in the presence of such dependent failure behavior. The authors used 20 redundant programs from a software reliability experiment to analyze the software errors causing coincident failures, to compare the reliability of N-version and recovery block structures composed of these programs, and to examine the impact of diversity on software reliability using subpopulations of these programs. The results indicate that both conceptually related and unrelated errors can cause coincident failures and that recovery block structures offer more reliability gain than N-version structures if acceptance checks that fail independently from the software components are available. The authors present a theory of general program checkers that have potential application for acceptance tests.

  15. Individual Differences in Human Reliability Analysis

    Jeffrey C. Joe; Ronald L. Boring


    While human reliability analysis (HRA) methods include uncertainty in quantification, the nominal model of human error in HRA typically assumes that operator performance does not vary significantly when they are given the same initiating event, indicators, procedures, and training, and that any differences in operator performance are simply aleatory (i.e., random). While this assumption generally holds true when performing routine actions, variability in operator response has been observed in multiple studies, especially in complex situations that go beyond training and procedures. As such, complexity can lead to differences in operator performance (e.g., operator understanding and decision-making). Furthermore, psychological research has shown that there are a number of known antecedents (i.e., attributable causes) that consistently contribute to observable and systematically measurable (i.e., not random) differences in behavior. This paper reviews examples of individual differences taken from operational experience and the psychological literature. The impact of these differences in human behavior and their implications for HRA are then discussed. We propose that individual differences should not be treated as aleatory, but rather as epistemic. Ultimately, by understanding the sources of individual differences, it is possible to remove some epistemic uncertainty from analyses.

  16. Fault Diagnosis and Reliability Analysis Using Fuzzy Logic Method

    Miao Zhinong; Xu Yang; Zhao Xiangyu


    A new fuzzy logic fault diagnosis method is proposed. In this method, fuzzy equations are employed to estimate the component state of a system based on the measured system performance and the relationship between component state and system performance which is called as "performance-parameter" knowledge base and constructed by expert. Compared with the traditional fault diagnosis method, this fuzzy logic method can use humans intuitive knowledge and dose not need a precise mapping between system performance and component state. Simulation proves its effectiveness in fault diagnosis. Then, the reliability analysis is performed based on the fuzzy logic method.

  17. 基于GO法的汽车EPS系统可靠性分析%Reliability Analysis of Vehicle' s EPS System Based on GO Methodology

    游专; 何仁


    In view of the limitations of the traditional methods of vehicle EPS system reliability assessment, the GO methodology was applied to analyze the system reliability. In this paper, specific analysis steps of the GO methodology were described, the corresponding GO diagram model was built, and a precise quantitative analysis and qualitative analysis were given. Finally, by comparing the analysis of the EPS with that of the FTA ( fault tree analysis) and the FMEA(failure modes and effects analysis) , accuracy of the GO method was verified. The results show that the Go method is a kind of practical method to analyze the reliability of vehicle' s EPS, which can reduce the workload and modeling errors.%针对现有汽车EPS系统可靠性评估传统方法的局限性,应用GO法对EPS系统进行可靠性分析.阐述了汽车EPS系统GO法的具体分析步骤,建立了相应GO图模型,进行了定性分析和精确的定量分析.通过与FTA分析和FMEA分析法对同一EPS的分析对比验证了GO法在汽车EPS进行可靠性分析中的实用性和正确性.结果表明应用GO法进行汽车EPS可靠性分析,是一种具有实际操作意义的解决方案,可以减少计算工作量和降低建模差错.

  18. Reliable Quantification of the Potential for Equations Based on Spot Urine Samples to Estimate Population Salt Intake: Protocol for a Systematic Review and Meta-Analysis

    Huang, Liping; Crino, Michelle; Wu, Jason HY; Woodward, Mark; Land, Mary-Anne; McLean, Rachael; Webster, Jacqui; Enkhtungalag, Batsaikhan; Nowson, Caryl A; Elliott, Paul; Cogswell, Mary; Toft, Ulla; MILL, Jose G.; Furlanetto,Tania W.; Ilich, Jasminka Z.


    Background Methods based on spot urine samples (a single sample at one time-point) have been identified as a possible alternative approach to 24-hour urine samples for determining mean population salt intake. Objective The aim of this study is to identify a reliable method for estimating mean population salt intake from spot urine samples. This will be done by comparing the performance of existing equations against one other and against estimates derived from 24-hour urine samples. The effect...

  19. Optimal, Reliability-Based Code Calibration

    Sørensen, John Dalsgaard


    acceptable levels of failure probability (or target reliabilities) may be established. Furthermore suggested values for acceptable annual failure probabilities are given for the ultimate and the serviceability limit states. Finally the paper describes a procedure for the practical implementation...

  20. Risk Based Reliability Centered Maintenance of DOD Fire Protection Systems


    Reliability Analysis of Underground Fire Water Piping at the Paducah Gaseous Diffusion Plant , January 1990. I I I I U B-8 3 I U I I I I APPENDIX C N...paper No. 7B, 1982. I3IEEE-Std-500-1984. 4INPO 83-034, Nuclear Plant Reliability Data Annual Report, October 1983. 5Nonelectronic Parts Reliability Data

  1. System Reliability for LED-Based Products

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


    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.


    Popescu V.S.


    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.




    Full Text Available Reliability is the probability that a system, component or device will perform without failure for a specified period of time under specified operating conditions. The concept of reliability is of great importance in the design of various machine members. Conventional engineering design uses a deterministic approach. It disregards the fact that the material properties, the dimensions of the components and the externally applied loads are statistical in nature. In conventional design this uncertainties are covered with a factor of safety, which is not always successful. The growing trend towards reducing uncertainty and increasing reliability is to use the probabilistic approach. In the present work a three shaft four speed gear box and six speed gear box are designed using reliability principles. For the specified reliability of the system (Gear box, component reliability (Gear pair is calculated by considering the system as a series system. Design is considered to be safe and adequate if the probability of failure of gear box is less than or equal to a specified quantity in each of the two failure modes. . All the parameters affecting the design are considered as random variables and all the random variables are assumed to follow normal distribution. A computer program in C++ is developed to calculate the face widths in bending and surface failure modes. The larger one out of the two values is considered. By changing the variations in the design parameters, variations in the face widths are studied.

  4. Analysis of Gumbel Model for Software Reliability Using Bayesian Paradigm

    Raj Kumar


    Full Text Available In this paper, we have illustrated the suitability of Gumbel Model for software reliability data. The model parameters are estimated using likelihood based inferential procedure: classical as well as Bayesian. The quasi Newton-Raphson algorithm is applied to obtain the maximum likelihood estimates and associated probability intervals. The Bayesian estimates of the parameters of Gumbel model are obtained using Markov Chain Monte Carlo(MCMC simulation method in OpenBUGS(established software for Bayesian analysis using Markov Chain Monte Carlo methods. The R functions are developed to study the statistical properties, model validation and comparison tools of the model and the output analysis of MCMC samples generated from OpenBUGS. Details of applying MCMC to parameter estimation for the Gumbel model are elaborated and a real software reliability data set is considered to illustrate the methods of inference discussed in this paper.

  5. Reliability Analysis on English Writing Test of SHSEE in Shanghai

    黄玉麒; 黄芳


    As a subjective test, the validity of writing test is acceptable. What about the reliability? Writing test occupies a special position in the senior high school entrance examination (SHSEE for short). It is important to ensure its reliability. By the analysis of recent years’English writing items in SHSEE, the author offer suggestions on how to guarantee the reliability of writing tests.


    C.L. Liu; Z.Z. Lü; Y.L. Xu


    Reliability analysis methods based on the linear damage accumulation law (LDAL) and load-life interference model are studied in this paper. According to the equal probability rule, the equivalent loads are derived, and the reliability analysis method based on load-life interference model and recurrence formula is constructed. In conjunction with finite element analysis (FEA) program, the reliability of an aero engine turbine disk under low cycle fatigue (LCF) condition has been analyzed. The results show the turbine disk is safety and the above reliability analysis methods are feasible.

  7. Analysis on Some of Software Reliability Models


    Software reliability & maintainability evaluation tool (SRMET 3.0) is introducted in detail in this paper,which was developed by Software Evaluation and Test Center of China Aerospace Mechanical Corporation. SRMET 3.0is supported by seven soft ware reliability models and four software maintainability models. Numerical characteristicsfor all those models are deeply studied in this paper, and corresponding numerical algorithms for each model are alsogiven in the paper.

  8. Reliability-Based Optimization and Optimal Reliability Level of Offshore Wind Turbines

    Tarp-Johansen, N.J.; Sørensen, John Dalsgaard


    Different formulations relevant for the reliability-based optimization of offshore wind turbines are presented, including different reconstruction policies in case of failure. Illustrative examples are presented and, as a part of the results, optimal reliability levels for the different failure m...

  9. Reliability-Based Optimization and Optimal Reliability Level of Offshore Wind Turbines

    Sørensen, John Dalsgaard; Tarp-Johansen, N.J.


    Different formulations relevant for the reliability-based optimization of offshore wind turbines are presented, including different reconstruction policies in case of failure. Illustrative examples are presented and, as a part of the results, optimal reliability levels for the different failure...


    Zhao Jingyi; Zhuoru; Wang Yiqun


    According to the demand of high reliability of the primary cylinder of the hydraulic press,the reliability model of the primary cylinder is built after its reliability analysis.The stress of the primary cylinder is analyzed by finite element software-MARC,and the structure reliability of the cylinder based on stress-strength model is predicted,which would provide the reference to the design.

  11. An efficient approach for reliability-based topology optimization

    Kanakasabai, Pugazhendhi; Dhingra, Anoop K.


    This article presents an efficient approach for reliability-based topology optimization (RBTO) in which the computational effort involved in solving the RBTO problem is equivalent to that of solving a deterministic topology optimization (DTO) problem. The methodology presented is built upon the bidirectional evolutionary structural optimization (BESO) method used for solving the deterministic optimization problem. The proposed method is suitable for linear elastic problems with independent and normally distributed loads, subjected to deflection and reliability constraints. The linear relationship between the deflection and stiffness matrices along with the principle of superposition are exploited to handle reliability constraints to develop an efficient algorithm for solving RBTO problems. Four example problems with various random variables and single or multiple applied loads are presented to demonstrate the applicability of the proposed approach in solving RBTO problems. The major contribution of this article comes from the improved efficiency of the proposed algorithm when measured in terms of the computational effort involved in the finite element analysis runs required to compute the optimum solution. For the examples presented with a single applied load, it is shown that the CPU time required in computing the optimum solution for the RBTO problem is 15-30% less than the time required to solve the DTO problems. The improved computational efficiency allows for incorporation of reliability considerations in topology optimization without an increase in the computational time needed to solve the DTO problem.



    The optimum design method based on the reliability is presented to the stochastic structure systems (i. e., the sectional area, length, elastic module and strength of the structural member are random variables) under the random loads. The sensitivity expression of system reliability index and the safety margins were presented in the stochastic structure systems. The optimum vector method was given. First, the expressions of the reliability index of the safety margins with the improved first-order second-moment and the stochastic finite element method were deduced, and then the expressions of the systemic failure probability by probabilistic network evaluation technique(PNET) method were obtained. After derivation calculus, the expressions of the sensitivity analysis for the system reliability were obtained. Moreover, the optimum design with the optimum vector algorithm was undertaken. In the optimum iterative procedure, the gradient step and the optimum vector step were adopted to calculate. At the last, a numerical example was provided to illustrate that the method is efficient in the calculation, stably converges and fits the application in engineering.

  13. Human Reliability Analysis for Design: Using Reliability Methods for Human Factors Issues

    Ronald Laurids Boring


    This paper reviews the application of human reliability analysis methods to human factors design issues. An application framework is sketched in which aspects of modeling typically found in human reliability analysis are used in a complementary fashion to the existing human factors phases of design and testing. The paper provides best achievable practices for design, testing, and modeling. Such best achievable practices may be used to evaluate and human system interface in the context of design safety certifications.

  14. Human Performance Modeling for Dynamic Human Reliability Analysis

    Boring, Ronald Laurids [Idaho National Laboratory; Joe, Jeffrey Clark [Idaho National Laboratory; Mandelli, Diego [Idaho National Laboratory


    Part of the U.S. Department of Energy’s (DOE’s) Light Water Reac- tor Sustainability (LWRS) Program, the Risk-Informed Safety Margin Charac- terization (RISMC) Pathway develops approaches to estimating and managing safety margins. RISMC simulations pair deterministic plant physics models with probabilistic risk models. As human interactions are an essential element of plant risk, it is necessary to integrate human actions into the RISMC risk framework. In this paper, we review simulation based and non simulation based human reliability analysis (HRA) methods. This paper summarizes the founda- tional information needed to develop a feasible approach to modeling human in- teractions in RISMC simulations.

  15. Reliability-Based Planning of Chloride Measurements

    Sørensen, John Dalsgaard; Engelund, S.


    on measurements of the chloride content obtained from the given structure. In the present paper optimal planning of measurements of the chloride content in reinforced concrete structures is considered. It is shown how optimal experimental plans can be obtained using FORM-analysis. Bayesian statistics are used......In reinforced concrete structures corrosion is initiated when the chloride concentration around the reinforcement exceeds a threshold value. If corrosion starts then expensive repairs can be necessary. The estimation of the probability that corrosion has been initiated in a given structure is based...


    LIU Deshun; YUE Wenhui; ZHU Pingyu; DU Xiaoping


    Conventional reliability-based design optimization (RBDO) requires to use the most probable point (MPP) method for a probabilistic analysis of the reliability constraints. A new approach is presented, called as the minimum error point (MEP) method or the MEP based method,for reliability-based design optimization, whose idea is to minimize the error produced by approximating performance functions. The MEP based method uses the first order Taylor's expansion at MEP instead of MPP. Examples demonstrate that the MEP based design optimization can ensure product reliability at the required level, which is very imperative for many important engineering systems. The MEP based reliability design optimization method is feasible and is considered as an alternative for solving reliability design optimization problems. The MEP based method is more robust than the commonly used MPP based method for some irregular performance functions.

  17. Reliability-Based Optimization of Structural Elements

    Sørensen, John Dalsgaard

    In this paper structural elements from an optimization point of view are considered, i.e. only the geometry of a structural element is optimized. Reliability modelling of the structural element is discussed both from an element point of view and from a system point of view. The optimization...

  18. Reliability Based Management of Marine Fouling

    Faber, Michael Havbro; Hansen, Peter Friis


    The present paper describes the results of a recent study on the application of methods from structural reliability to optimise management of marine fouling on jacket type structures.In particular the study addresses effects on the structural response by assessment and quantification of uncertain...

  19. Using functional analysis diagrams to improve product reliability and cost

    Ioannis Michalakoudis


    Full Text Available Failure mode and effects analysis and value engineering are well-established methods in the manufacturing industry, commonly applied to optimize product reliability and cost, respectively. Both processes, however, require cross-functional teams to identify and evaluate the product/process functions and are resource-intensive, hence their application is mostly limited to large organizations. In this article, we present a methodology involving the concurrent execution of failure mode and effects analysis and value engineering, assisted by a set of hierarchical functional analysis diagram models, along with the outcomes of a pilot application in a UK-based manufacturing small and medium enterprise. Analysis of the results indicates that this new approach could significantly enhance the resource efficiency and effectiveness of both failure mode and effects analysis and value engineering processes.

  20. Reliability estimation in a multilevel confirmatory factor analysis framework.

    Geldhof, G John; Preacher, Kristopher J; Zyphur, Michael J


    Scales with varying degrees of measurement reliability are often used in the context of multistage sampling, where variance exists at multiple levels of analysis (e.g., individual and group). Because methodological guidance on assessing and reporting reliability at multiple levels of analysis is currently lacking, we discuss the importance of examining level-specific reliability. We present a simulation study and an applied example showing different methods for estimating multilevel reliability using multilevel confirmatory factor analysis and provide supporting Mplus program code. We conclude that (a) single-level estimates will not reflect a scale's actual reliability unless reliability is identical at each level of analysis, (b) 2-level alpha and composite reliability (omega) perform relatively well in most settings, (c) estimates of maximal reliability (H) were more biased when estimated using multilevel data than either alpha or omega, and (d) small cluster size can lead to overestimates of reliability at the between level of analysis. We also show that Monte Carlo confidence intervals and Bayesian credible intervals closely reflect the sampling distribution of reliability estimates under most conditions. We discuss the estimation of credible intervals using Mplus and provide R code for computing Monte Carlo confidence intervals.

  1. Reliability Analysis of Dynamic Stability in Waves

    Søborg, Anders Veldt


    exhibit sufficient characteristics with respect to slope at zero heel (GM value), maximum leverarm, positive range of stability and area below the leverarm curve. The rule-based requirements to calm water leverarm curves are entirely based on experience obtained from vessels in operation and recorded......-4 per ship year such brute force Monte-Carlo simulations are not always feasible due to the required computational resources. Previous studies of dynamic stability of ships in waves typically focused on the capsizing event. In this study the objective is to establish a procedure that can identify...... the distribution of the exceedance probability may be established by an estimation of the out-crossing rate of the "safe set" defined by the utility function. This out-crossing rate will be established using the so-called Madsen's Formula. A bi-product of this analysis is a set of short wave time series...

  2. Analysis of Reliability of CET Band4



    CET Band 4 has been carried out for more than a decade. It becomes so large- scaled, so popular and so influential that many testing experts and foreign language teachers are willing to do research on it. In this paper, I will mainly analyse its reliability from the perspective of writing test and speaking test.

  3. Reliability Analysis of an Offshore Structure

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle; Rackwitz, R.


    A jacket type offshore structure from the North Sea is considered. The time variant reliability is estimated for failure defined as brittie fradure and crack through the tubular roerober walls. The stochastic modeiling is described. The hot spot stress speetral moments as fundion of the stochastic...

  4. Analytical reliability analysis of soil-water characteristic curve

    Johari A.


    Full Text Available The Soil Water Characteristic Curve (SWCC, also known as the soil water-retention curve, is an important part of any constitutive relationship for unsaturated soils. Deterministic assessment of SWCC has received considerable attention in the past few years. However the uncertainties of the parameters which affect SWCC dictate that the problem is of a probabilistic nature rather than being deterministic. In this research, a Gene Expression Programming (GEP-based SWCC model is employed to assess the reliability of SWCC. For this purpose, the Jointly Distributed Random Variables (JDRV method is used as an analytical method for reliability analysis. All input parameters of the model which are initial void ratio, initial water content, silt and clay contents are set to be stochastic and modelled using truncated normal probability density functions. The results are compared with those of the Monte Carlo (MC simulation. It is shown that the initial water content is the most effective parameter in SWCC.

  5. Study of vertical breakwater reliability based on copulas

    Dong, Sheng; Li, Jingjing; Li, Xue; Wei, Yong


    The reliability of a vertical breakwater is calculated using direct integration methods based on joint density functions. The horizontal and uplifting wave forces on the vertical breakwater can be well fitted by the lognormal and the Gumbel distributions, respectively. The joint distribution of the horizontal and uplifting wave forces is analyzed using different probabilistic distributions, including the bivariate logistic Gumbel distribution, the bivariate lognormal distribution, and three bivariate Archimedean copulas functions constructed with different marginal distributions simultaneously. We use the fully nested copulas to construct multivariate distributions taking into account related variables. Different goodness fitting tests are carried out to determine the best bivariate copula model for wave forces on a vertical breakwater. We show that a bivariate model constructed by Frank copula gives the best reliability analysis, using marginal distributions of Gumbel and lognormal to account for uplifting pressure and horizontal wave force on a vertical breakwater, respectively. The results show that failure probability of the vertical breakwater calculated by multivariate density function is comparable to those by the Joint Committee on Structural Safety methods. As copulas are suitable for constructing a bivariate or multivariate joint distribution, they have great potential in reliability analysis for other coastal structures.


    G. W. Parry; J.A Forester; V.N. Dang; S. M. L. Hendrickson; M. Presley; E. Lois; J. Xing


    This paper describes a method, IDHEAS (Integrated Decision-Tree Human Event Analysis System) that has been developed jointly by the US NRC and EPRI as an improved approach to Human Reliability Analysis (HRA) that is based on an understanding of the cognitive mechanisms and performance influencing factors (PIFs) that affect operator responses. The paper describes the various elements of the method, namely the performance of a detailed cognitive task analysis that is documented in a crew response tree (CRT), and the development of the associated time-line to identify the critical tasks, i.e. those whose failure results in a human failure event (HFE), and an approach to quantification that is based on explanations of why the HFE might occur.

  7. Reliability analysis of the Chinese version of the Functional Assessment of Cancer Therapy - Leukemia (FACT-Leu) scale based on multivariate generalizability theory.

    Meng, Qiong; Yang, Zheng; Wu, Yang; Xiao, Yuanyuan; Gu, Xuezhong; Zhang, Meixia; Wan, Chonghua; Li, Xiaosong


    The Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu) scale, a leukemia-specific instrument for determining the health-related quality of life (HRQOL) in patients with leukemia, had been developed and validated, but there have been no reports on the development of a simplified Chinese version of this scale. This is a new exploration to analyze the reliability of the HRQOL measurement using multivariate generalizability theory (MGT). This study aimed to develop a Chinese version of the FACT-Leu scale and evaluate its reliability using MGT to provide evidence to support the revision and improvement of this scale. The Chinese version of the FACT-Leu scale was developed by four steps: forward translation, backward translation, cultural adaptation and pilot-testing. The HRQOL was measured for eligible inpatients with leukemia using this scale to provide data. A single-facet multivariate Generalizability Study (G-study) design was demonstrated to estimate the variance-covariance components and then several Decision Studies (D-studies) with varying numbers of items were analyzed to obtain reliability coefficients and to understand how much the measurement reliability could be vary as the number of items in MGT changes. One-hundred and one eligible inpatients diagnosed with leukemia were recruited and completed the HRQOL measurement at the time of admission to the hospital. In the G-study, the variation component of the patient-item interaction was largest while the variation component of the item was the smallest for the four of five domains, except for the leukemia-specific (LEUS) domain. In the D-study, at the level of domain, the generalizability coefficients (G) and the indexes of dependability (Ф) for four of the five domains were approximately equal to or greater than 0.80 except for the Emotional Well-being (EWB) domain (>0.70 but FACT-Leu scale has good reliability as a whole based on the results of MGT and the implementation of MGT could lead to more

  8. Reliability-Based Inspection Planning for Structural Systems

    Sørensen, John Dalsgaard


    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...

  9. Establishing maintenance intervals based on measurement reliability of engineering endpoints.

    James, P J


    Methods developed by the metrological community and principles used by the research community were integrated to provide a basis for a periodic maintenance interval analysis system. Engineering endpoints are used as measurement attributes on which to base two primary quality indicators: accuracy and reliability. Also key to establishing appropriate maintenance intervals is the ability to recognize two primary failure modes: random failure and time-related failure. The primary objective of the maintenance program is to avert predictable and preventable device failure, and understanding time-related failures enables service personnel to set intervals accordingly.

  10. Fatigue Reliability Analysis of Wind Turbine Cast Components

    Hesam Mirzaei Rafsanjani


    Full Text Available The fatigue life of wind turbine cast components, such as the main shaft in a drivetrain, is generally determined by defects from the casting process. These defects may reduce the fatigue life and they are generally distributed randomly in components. The foundries, cutting facilities and test facilities can affect the verification of properties by testing. Hence, it is important to have a tool to identify which foundry, cutting and/or test facility produces components which, based on the relevant uncertainties, have the largest expected fatigue life or, alternatively, have the largest reliability to be used for decision-making if additional cost considerations are added. In this paper, a statistical approach is presented based on statistical hypothesis testing and analysis of covariance (ANCOVA which can be applied to compare different groups (manufacturers, suppliers, test facilities, etc. and to quantify the relevant uncertainties using available fatigue tests. Illustrative results are presented as obtained by statistical analysis of a large set of fatigue data for casted test components typically used for wind turbines. Furthermore, the SN curves (fatigue life curves based on applied stress for fatigue assessment are estimated based on the statistical analyses and by introduction of physical, model and statistical uncertainties used for the illustration of reliability assessment.

  11. Reliability analysis of ceramic matrix composite laminates

    Thomas, David J.; Wetherhold, Robert C.


    At a macroscopic level, a composite lamina may be considered as a homogeneous orthotropic solid whose directional strengths are random variables. Incorporation of these random variable strengths into failure models, either interactive or non-interactive, allows for the evaluation of the lamina reliability under a given stress state. Using a non-interactive criterion for demonstration purposes, laminate reliabilities are calculated assuming previously established load sharing rules for the redistribution of load as the failure of laminae occur. The matrix cracking predicted by ACK theory is modeled to allow a loss of stiffness in the fiber direction. The subsequent failure in the fiber direction is controlled by a modified bundle theory. Results using this modified bundle model are compared with previous models which did not permit separate consideration of matrix cracking, as well as to results obtained from experimental data.

  12. An efficient approach to reliability-based design optimization within the enhanced sequential optimization and reliability assessment framework

    Huang, Hong Zhong; Zhang, Xudong; Meng, De Biao; Wang, Zhonglai; Liu, Yu [University of Electronic Science and Technology of China, Chengdu (China)


    Reliability based design optimization (RBDO) has been widely implemented in engineering practices for high safety and reliability. It is an important challenge to improve computational efficiency. Sequential optimization and reliability assessment (SORA) has made great efforts to improve computational efficiency by decoupling a RBDO problem into sequential deterministic optimization and reliability analysis as a single-loop method. In this paper, in order to further improve computational efficiency and extend the application of the current SORA method, an enhanced SORA (ESORA) is proposed by considering constant and varying variances of random design variables while keeping the sequential framework. Some mathematical examples and an engineering case are given to illustrate the proposed method and validate the efficiency.

  13. A reliability analysis of the revised competitiveness index.

    Harris, Paul B; Houston, John M


    This study examined the reliability of the Revised Competitiveness Index by investigating the test-retest reliability, interitem reliability, and factor structure of the measure based on a sample of 280 undergraduates (200 women, 80 men) ranging in age from 18 to 28 years (M = 20.1, SD = 2.1). The findings indicate that the Revised Competitiveness Index has high test-retest reliability, high inter-item reliability, and a stable factor structure. The results support the assertion that the Revised Competitiveness Index assesses competitiveness as a stable trait rather than a dynamic state.

  14. DFTCalc: Reliability centered maintenance via fault tree analysis (tool paper)

    Guck, Dennis; Spel, Jip; Stoelinga, Mariëlle Ida Antoinette; Butler, Michael; Conchon, Sylvain; Zaïdi, Fatiha


    Reliability, availability, maintenance and safety (RAMS) analysis is essential in the evaluation of safety critical systems like nuclear power plants and the railway infrastructure. A widely used methodology within RAMS analysis are fault trees, representing failure propagations throughout a system.

  15. DFTCalc: reliability centered maintenance via fault tree analysis (tool paper)

    Guck, Dennis; Spel, Jip; Stoelinga, Mariëlle; Butler, Michael; Conchon, Sylvain; Zaïdi, Fatiha


    Reliability, availability, maintenance and safety (RAMS) analysis is essential in the evaluation of safety critical systems like nuclear power plants and the railway infrastructure. A widely used methodology within RAMS analysis are fault trees, representing failure propagations throughout a system.


    Gaguk Margono


    Full Text Available The purpose of this paper is to compare unidimensional reliability and multidimensional reliability of instrument students’ satisfaction as an internal costumer. Multidimensional reliability measurement is rarely used in the field of research. Multidimensional reliability is estimated by using Confirmatory Factor Analysis (CFA on the Structural Equation Model (SEM. Measurements and calculations are described in this article using instrument students’ satisfaction as an internal costumer. Survey method used in this study and sampling used simple random sampling. This instrument has been tried out to 173 students. The result is concluded that the measuringinstrument of students’ satisfaction as an internal costumer by using multidimensional reliability coefficient has higher accuracy when compared with a unidimensional reliability coefficient. Expected in advanced research used another formula multidimensional reliability, including when using SEM.

  17. Reliability analysis of PLC safety equipment

    Yu, J.; Kim, J. Y. [Chungnam Nat. Univ., Daejeon (Korea, Republic of)


    FMEA analysis for Nuclear Safety Grade PLC, failure rate prediction for nuclear safety grade PLC, sensitivity analysis for components failure rate of nuclear safety grade PLC, unavailability analysis support for nuclear safety system.

  18. Earth slope reliability analysis under seismic loadings using neural network

    PENG Huai-sheng; DENG Jian; GU De-sheng


    A new method was proposed to cope with the earth slope reliability problem under seismic loadings. The algorithm integrates the concepts of artificial neural network, the first order second moment reliability method and the deterministic stability analysis method of earth slope. The performance function and its derivatives in slope stability analysis under seismic loadings were approximated by a trained multi-layer feed-forward neural network with differentiable transfer functions. The statistical moments calculated from the performance function values and the corresponding gradients using neural network were then used in the first order second moment method for the calculation of the reliability index in slope safety analysis. Two earth slope examples were presented for illustrating the applicability of the proposed approach. The new method is effective in slope reliability analysis. And it has potential application to other reliability problems of complicated engineering structure with a considerably large number of random variables.

  19. Design and Analysis for Reliability of Wireless Sensor Network

    Yongxian Song


    Full Text Available Reliability is an important performance indicator of wireless sensor network, to some application fields, which have high demands in terms of reliability, it is particularly important to ensure reliability of network. At present, the reliability research findings of wireless sensor network are much more at home and abroad, but they mainly improve network reliability from the networks topology, reliable protocol and application layer fault correction and so on, and reliability of network is comprehensive considered from hardware and software aspects is much less. This paper adopts bionic hardware to implement bionic reconfigurable of wireless sensor network nodes, so as to the nodes have able to change their structure and behavior autonomously and dynamically, in the cases of the part hardware are failure, and the nodes can realize bionic self-healing. Secondly, Markov state diagram and probability analysis method are adopted to realize solution of functional model for reliability, establish the relationship between reliability and characteristic parameters for sink nodes, analyze sink nodes reliability model, so as to determine the reasonable parameters of the model and ensure reliability of sink nodes.

  20. Transformer real-time reliability model based on operating conditions

    HE Jian; CHENG Lin; SUN Yuan-zhang


    Operational reliability evaluation theory reflects real-time reliability level of power system. The component failure rate varies with operating conditions. The impact of real-time operating conditions such as ambient temperature and transformer MVA (megavolt-ampere) loading on transformer insulation life is studied in this paper. The formula of transformer failure rate based on the winding hottest-spot temperature (HST) is given. Thus the real-time reliability model of transformer based on operating conditions is presented. The work is illustrated using the 1979 IEEE Reliability Test System. The changes of operating conditions are simulated by using hourly load curve and temperature curve, so the curves of real-time reliability indices are obtained by using operational reliability evaluation.

  1. Integrated Software Architecture-Based Reliability Prediction for IT Systems

    Brosch, Franz


    With the increasing importance of reliability in business and industrial IT systems, new techniques for architecture-based software reliability prediction are becoming an integral part of the development process. This dissertation thesis introduces a novel reliability modelling and prediction technique that considers the software architecture with its component structure, control and data flow, recovery mechanisms, its deployment to distributed hardware resources and the system´s usage p...

  2. Reliability and risk analysis using artificial neural networks

    Robinson, D.G. [Sandia National Labs., Albuquerque, NM (United States)


    This paper discusses preliminary research at Sandia National Laboratories into the application of artificial neural networks for reliability and risk analysis. The goal of this effort is to develop a reliability based methodology that captures the complex relationship between uncertainty in material properties and manufacturing processes and the resulting uncertainty in life prediction estimates. The inputs to the neural network model are probability density functions describing system characteristics and the output is a statistical description of system performance. The most recent application of this methodology involves the comparison of various low-residue, lead-free soldering processes with the desire to minimize the associated waste streams with no reduction in product reliability. Model inputs include statistical descriptions of various material properties such as the coefficients of thermal expansion of solder and substrate. Consideration is also given to stochastic variation in the operational environment to which the electronic components might be exposed. Model output includes a probabilistic characterization of the fatigue life of the surface mounted component.

  3. Reliability analysis of large, complex systems using ASSIST

    Johnson, Sally C.


    The SURE reliability analysis program is discussed as well as the ASSIST model generation program. It is found that semi-Markov modeling using model reduction strategies with the ASSIST program can be used to accurately solve problems at least as complex as other reliability analysis tools can solve. Moreover, semi-Markov analysis provides the flexibility needed for modeling realistic fault-tolerant systems.


    陈涛; 孙伟; 张旭


    In order to increase the accuracy of fault tree analysis and improve the predictive viaracity of reliability analysis, the transmission qear box of wind power was provided as study case. Fault tree model was divided into several sub-units and grey relation theory was used to establish the reliability links between various units. In the base unit, basic feature events were defined to generalize the probability characteristics of similar basic events. In addition, rftliability of each basic feature events was calculated by stress-strength interference model and Monte Carlo method. Based on these work, reliability of whole transmission can be solved. The results indicate that the method an improve the objectivity of reliability analysis, and the system reliability can be predicted fleetly if the design parameters are known.%为提高故障树分析在可靠性预测过程中的准确性,以风电齿轮箱传动系统为研究对象,将故障树模型划分为若干子单元,利用灰色关联度理论建立各单元之间的可靠度联系;对于基准单元,定义基本特征事件表征同类底事件的概率特征,利用应力-强度干涉模型及蒙特卡罗数值法模拟各基本特征事件的可靠度,在此基础上求解整个传动系统的可靠度.结果表明:该方法不仅可提高可靠度计算的客观性,且能够在设计参数已知的前提下对系统可靠度进行快速预测.

  5. Tailoring a Human Reliability Analysis to Your Industry Needs

    DeMott, D. L.


    Companies at risk of accidents caused by human error that result in catastrophic consequences include: airline industry mishaps, medical malpractice, medication mistakes, aerospace failures, major oil spills, transportation mishaps, power production failures and manufacturing facility incidents. Human Reliability Assessment (HRA) is used to analyze the inherent risk of human behavior or actions introducing errors into the operation of a system or process. These assessments can be used to identify where errors are most likely to arise and the potential risks involved if they do occur. Using the basic concepts of HRA, an evolving group of methodologies are used to meet various industry needs. Determining which methodology or combination of techniques will provide a quality human reliability assessment is a key element to developing effective strategies for understanding and dealing with risks caused by human errors. There are a number of concerns and difficulties in "tailoring" a Human Reliability Assessment (HRA) for different industries. Although a variety of HRA methodologies are available to analyze human error events, determining the most appropriate tools to provide the most useful results can depend on industry specific cultures and requirements. Methodology selection may be based on a variety of factors that include: 1) how people act and react in different industries, 2) expectations based on industry standards, 3) factors that influence how the human errors could occur such as tasks, tools, environment, workplace, support, training and procedure, 4) type and availability of data, 5) how the industry views risk & reliability, and 6) types of emergencies, contingencies and routine tasks. Other considerations for methodology selection should be based on what information is needed from the assessment. If the principal concern is determination of the primary risk factors contributing to the potential human error, a more detailed analysis method may be employed

  6. Reliability and safety analysis of redundant vehicle management computer system

    Shi Jian; Meng Yixuan; Wang Shaoping; Bian Mengmeng; Yan Dungong


    Redundant techniques are widely adopted in vehicle management computer (VMC) to ensure that VMC has high reliability and safety. At the same time, it makes VMC have special char-acteristics, e.g., failure correlation, event simultaneity, and failure self-recovery. Accordingly, the reliability and safety analysis to redundant VMC system (RVMCS) becomes more difficult. Aimed at the difficulties in RVMCS reliability modeling, this paper adopts generalized stochastic Petri nets to establish the reliability and safety models of RVMCS. Then this paper analyzes RVMCS oper-ating states and potential threats to flight control system. It is verified by simulation that the reli-ability of VMC is not the product of hardware reliability and software reliability, and the interactions between hardware and software faults can reduce the real reliability of VMC obviously. Furthermore, the failure undetected states and false alarming states inevitably exist in RVMCS due to the influences of limited fault monitoring coverage and false alarming probability of fault mon-itoring devices (FMD). RVMCS operating in some failure undetected states will produce fatal threats to the safety of flight control system. RVMCS operating in some false alarming states will reduce utility of RVMCS obviously. The results abstracted in this paper can guide reliable VMC and efficient FMD designs. The methods adopted in this paper can also be used to analyze other intelligent systems’ reliability.

  7. Optimal Reliability-Based Planning of Experiments for POD Curves

    Sørensen, John Dalsgaard; Faber, M. H.; Kroon, I. B.

    Optimal planning of the crack detection test is considered. The test are used to update the information on the reliability of the inspection techniques modelled by probability of detection (P.O.D.) curves. It is shown how cost-optimal and reliability based test plans can be obtained using First O...... Order Reliability Methods in combination with life-cycle cost-optimal inspection and maintenance planning. The methodology is based on preposterior analyses from Bayesian decision theory. An illustrative example is shown.......Optimal planning of the crack detection test is considered. The test are used to update the information on the reliability of the inspection techniques modelled by probability of detection (P.O.D.) curves. It is shown how cost-optimal and reliability based test plans can be obtained using First...

  8. Reliability-based design of wind turbine blades

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard


    Reliability-based design of wind turbine blades requires identification of the important failure modes/limit states along with stochastic models for the uncertainties and methods for estimating the reliability. In the present paper it is described how reliability-based design can be applied to wind...... turbine blades. For wind turbine blades, tests with the basic composite materials and a few full-scale blades are normally performed during the design process. By adopting a reliability-based design approach, information from these tests can be taken into account in a rational way during the design...... process. In the present paper, a probabilistic framework for design of wind turbine blades are presented and it is demonstrated how information from tests can be taken into account using the Maximum-Likelihood method and Bayesian statistics. In a numerical example, the reliability is estimated for a wind...

  9. Reliability-based design of wind turbine blades

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard


    Reliability-based design of wind turbine blades requires identification of the important failure modes/limit states along with stochastic models for the uncertainties and methods for estimating the reliability. In the present paper it is described how reliability-based design can be applied to wind...... turbine blades. For wind turbine blades, tests with the basic composite materials and a few full-scale blades are normally performed during the design process. By adopting a reliability-based design approach, information from these tests can be taken into account in a rational way during the design...... process. In the present paper, a probabilistic framework for design of wind turbine blades are presented and it is demonstrated how information from tests can be taken into account using the Maximum-Likelihood method and Bayesian statistics. In a numerical example, the reliability is estimated for a wind...

  10. Fifty Years of THERP and Human Reliability Analysis

    Ronald L. Boring


    In 1962 at a Human Factors Society symposium, Alan Swain presented a paper introducing a Technique for Human Error Rate Prediction (THERP). This was followed in 1963 by a Sandia Laboratories monograph outlining basic human error quantification using THERP and, in 1964, by a special journal edition of Human Factors on quantification of human performance. Throughout the 1960s, Swain and his colleagues focused on collecting human performance data for the Sandia Human Error Rate Bank (SHERB), primarily in connection with supporting the reliability of nuclear weapons assembly in the US. In 1969, Swain met with Jens Rasmussen of Risø National Laboratory and discussed the applicability of THERP to nuclear power applications. By 1975, in WASH-1400, Swain had articulated the use of THERP for nuclear power applications, and the approach was finalized in the watershed publication of the NUREG/CR-1278 in 1983. THERP is now 50 years old, and remains the most well known and most widely used HRA method. In this paper, the author discusses the history of THERP, based on published reports and personal communication and interviews with Swain. The author also outlines the significance of THERP. The foundations of human reliability analysis are found in THERP: human failure events, task analysis, performance shaping factors, human error probabilities, dependence, event trees, recovery, and pre- and post-initiating events were all introduced in THERP. While THERP is not without its detractors, and it is showing signs of its age in the face of newer technological applications, the longevity of THERP is a testament of its tremendous significance. THERP started the field of human reliability analysis. This paper concludes with a discussion of THERP in the context of newer methods, which can be seen as extensions of or departures from Swain’s pioneering work.

  11. Reliability forecasting of vehicles basing upon the graph of states

    Abramovich, M. S.; Prikhodko, Yu.


    The forecasting technique of reliability measures is described for the vehicle MAZ in monitoring maintenance. The base of the technique is mathematical model of vehicle maintenance as stochastic walk over a graph of state. The offered model enables to make a forecast of reliability measures both in time, and under the changing maintenance conditions or maintenance policy.

  12. Optimal Reliability-Based Planning of Experiments for POD Curves

    Sørensen, John Dalsgaard; Faber, M. H.; Kroon, I. B.

    Optimal planning of the crack detection test is considered. The test are used to update the information on the reliability of the inspection techniques modelled by probability of detection (P.O.D.) curves. It is shown how cost-optimal and reliability based test plans can be obtained using First...

  13. Reliability-based design optimization using a moment method and a kriging metamodel

    Ju, Byeong Hyeon; Chai Lee, Byung


    Reliability-based design optimization (RBDO) has been used for optimizing engineering systems with uncertainties in design variables and system parameters. RBDO involves reliability analysis, which requires a large amount of computational effort, so it is important to select an efficient method for reliability analysis. Of the many methods for reliability analysis, a moment method, which is called the fourth moment method, is known to be less expensive for moderate size problems and requires neither iteration nor the computation of derivatives. Despite these advantages, previous research on RBDO has been mainly based on the first-order reliability method and relatively little attention has been paid to moment-based RBDO. This article considers difficulties in implementing the moment method into RBDO; they are solved using a kriging metamodel with an active constraint strategy. Three numerical examples are tested and the results show that the proposed method is efficient and accurate.


    Rui Ge; Jianqiao Chen; Jnnhong Wei


    This paper proposed a reliability design model for composite materials under the mixture of random and interval variables. Together with the inverse reliability analysis technique, the sequential single-loop optimization method is applied to the reliability-based design of com-posites. In the sequential single-loop optimization, the optimization and the reliability analysis are decoupled to improve the computational efficiency. As shown in examples, the minimum weight problems under the constraint of structural reliability are solved for laminated composites. The Particle Swarm Optimization (PSO) algorithm is utilized to search for the optimal solutions. The design results indicate that, under the mixture of random and interval variables, the method that combines the sequential single-loop optimization and the PSO algorithm can deal effectively with the reliability-based design of composites.

  15. Optimal reliability-based design of offshore wind turbine parks

    Sørensen, John Dalsgaard


    that wind turbines are parked for wind speeds larger than 25 m/s resulting in reduced wind loads. Basic relationships are described for the mean wind velocity and turbulence intensity in wind turbine parks with emphasis on the spatial correlation. The expected total failure costs for the wind turbine park......A basic formulation for optimal reliability-based design of wind turbine parks is presented. Based on this model a probabilistic model and representative limit state equations for structural failure of wind turbine towers are formulated. The probability of failure is determined taking into account...... are estimated and normalised with a situation with only one wind turbine taking into account the spatial correlation. A sensitivity analysis is made with respect to parameters modelling the spatial correlation. Further, an optimization problem is formulated where a design parameter is the distance between...

  16. Identification of Black Spots Based on Reliability Approach

    Ahmadreza Ghaffari


    Full Text Available Identifying crash “black-spots”, “hot-spots” or “high-risk” locations is one of the most important and prevalent concerns in traffic safety and various methods have been devised and presented for solving this issue until now. In this paper, a new method based on the reliability analysis is presented to identify black-spots. Reliability analysis has an ordered framework to consider the probabilistic nature of engineering problems, so crashes with their probabilistic na -ture can be applied. In this study, the application of this new method was compared with the commonly implemented Frequency and Empirical Bayesian methods using simulated data. The results indicated that the traditional methods can lead to an inconsistent prediction due to their inconsider -ation of the variance of the number of crashes in each site and their dependence on the mean of the data.

  17. Method of reliability tolerance design based on EDA technology and its application on DC hybrid contactor

    WANG Shu-juan; SHA You-tao; ZHANG Hui; ZHAI Guo-fu


    Tolerance design, including tolerance analysis and distribution, is an important part of the electronic system's reliability design. The traditional design needs to construct mathematic model of material circuit, which involves large amount of workload and lacks of practicability. This paper discusses the basic theory of electronic system's reliability tolerance design and presents a new design method based on EDA (Electronic Design Automatic) software. This method has been validated through the application research on reliability tolerance design of the DC hybrid contactor's control circuit.

  18. Reliability Analysis of Bearing Capacity of Large-Diameter Piles under Osterberg Test

    Lei Nie


    Full Text Available This study gives the reliability analysis of bearing capacity of large-diameter piles under osterberg test. The limit state equation of dimensionless random variables is utilized in the reliability analysis of vertical bearing capacity of large-diameter piles based on Osterberg loading tests. And the reliability index and the resistance partial coefficient under the current specifications are calculated using calibration method. The results show: the reliable index of large-diameter piles is correlated with the load effect ratio and is smaller than the ordinary piles; resistance partial coefficient of 1.53 is proper in design of large-diameter piles.

  19. Reliability-Based Planning of Chloride Measurements

    Sørensen, John Dalsgaard; Engelund, S.


    on measurements of the chloride content obtained from the given structure. In the present paper optimal planning of measurements of the chloride content in reinforced concrete structures is considered. It is shown how optimal experimental plans can be obtained using FORM-analysis. Bayesian statistics are used...

  20. Reliability analysis of ship structure system with multi-defects


    This paper analyzes the influence of multi-defects including the initial distortions,welding residual stresses,cracks and local dents on the ultimate strength of the plate element,and has worked out expressions of reliability calculation and sensitivity analysis of the plate element.Reliability analysis is made for the system with multi-defects plate elements.Failure mechanism,failure paths and the calculating approach to global reliability index are also worked out.After plate elements with multi-defects fail,the formula of reverse node forces which affect the residual structure is deduced,so are the sensitivity expressions of the system reliability index.This ensures calculating accuracy and rationality for reliability analysis,and makes it convenient to find weakness plate elements which affect the reliability of the structure system.Finally,for the validity of the approach proposed,we take the numerical example of a ship cabin to compare and contrast the reliability and the sensitivity analysis of the structure system with multi-defects with those of the structure system with no defects.The approach has implications for the structure design,rational maintenance and renewing strategy.

  1. Reliability Assessment and Reliability-Based Inspection and Maintenance of Offshore Wind Turbines

    Ramírez, José G. Rangel; Sørensen, John Dalsgaard


    to optimize inspection and maintenance (I&M) efforts, entailing to a suitable life-cycle performance without neglecting the economical aspect. Moreover, the integration of condition monitoring information (CMI) can be done through probabilistic inference. In this work, a reliability-based I&M planning OWT...

  2. Reliability analysis of a Shift Platform Bracket Based on ANSYS%基于ANSYS的移动平台支架可靠性分析

    朱亚超; 程欣; 丁善婷; 何涛


    The ANSYS finite-element analysis software was adopted to analyze the displacement and deformation of solar energy testing shift platform bracket under weight of automatic tracker and solar panel during testing process.Form variable data was then compared with actual data.The results indicate that: adding one set of lock device and back-up unit at the end of shift platform bracket and reinforcing connection between platform bracket and back-up leg can improve safety and reliability of the whole platform bracket and testing device.%采用ANSYS有限元分析软件,对太阳能测试移动平台支架在测试过程中承受自动追踪器和太阳能集热板重量后发生的位移形变进行分析,比较计算形变量数据与实际数据,得出在移动平台支架尾部增加一组锁死装置和支撑装置,以加强移动平台与支撑腿连结,可提高整个平台支架和测试设备的安全性与可靠性的结论.

  3. Improved Reliability-Based Optimization with Support Vector Machines and Its Application in Aircraft Wing Design

    Yu Wang


    Full Text Available A new reliability-based design optimization (RBDO method based on support vector machines (SVM and the Most Probable Point (MPP is proposed in this work. SVM is used to create a surrogate model of the limit-state function at the MPP with the gradient information in the reliability analysis. This guarantees that the surrogate model not only passes through the MPP but also is tangent to the limit-state function at the MPP. Then, importance sampling (IS is used to calculate the probability of failure based on the surrogate model. This treatment significantly improves the accuracy of reliability analysis. For RBDO, the Sequential Optimization and Reliability Assessment (SORA is employed as well, which decouples deterministic optimization from the reliability analysis. The improved SVM-based reliability analysis is used to amend the error from linear approximation for limit-state function in SORA. A mathematical example and a simplified aircraft wing design demonstrate that the improved SVM-based reliability analysis is more accurate than FORM and needs less training points than the Monte Carlo simulation and that the proposed optimization strategy is efficient.

  4. Reliability Based Optimization of Fire Protection

    Thoft-Christensen, Palle

    fire protection (PFP) of firewalls and structural members. The paper is partly based on research performed within the EU supported research project B/E-4359 "Optimized Fire Safety of Offshore Structures" and partly on research supported by the Danish Technical Research Council (see Thoft-Christensen [1...

  5. Estimation on the Reliability of Farm Vehicle Based on Artificial Neural Network

    WANG Jinwu


    As a peculiar product in China today, farm vehicles play an important role in economic construction and development of the countryside, but its work reliability remains low. In this paper truncated tracking was used to solve the low reliability of farm vehicles. Relevant reliability data were obtained by tracking a certain model vehicle and conducting reliability experiments. Data analysis revealed the weakest part of the vehicle system was the engine assembly. The theory of Artificial Neural Network was employed to estimate a parameter of the reliability model based on self-adaptive linear neural network, and the reliability function educed by the estimation could provide important theory references for reliability reassignment, manufacture and management of farm transport vehicles.

  6. Methodology for maintenance analysis based on hydroelectric power stations reliability; Metodologia para realizar analisis de mantenimiento basado en confiabilidad en centrales hidroelectricas

    Rea Soto, Rogelio; Calixto Rodriguez, Roberto; Sandoval Valenzuela, Salvador; Velasco Flores, Rocio; Garcia Lizarraga, Maria del Carmen [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)


    A methodology to carry out Reliability Centered Maintenance (RCM) studies for hydroelectric power plants is presented. The methodology is an implantation/extension of the guidelines proposed by the Engineering Society for Advanced Mobility Land, Sea and Space in the SAE-JA1012 standard. With the purpose of answering the first five questions, that are set out in that standard, the use of standard ISO14224 is strongly recommended. This approach standardizes failure mechanisms and homogenizes RCM studies with the process of collecting failure and maintenance data. The use of risk matrixes to rank the importance of each failure based on a risk criteria is also proposed. [Spanish] Se presenta una metodologia para realizar estudios de mantenimiento Basado en Confiabilidad (RCM) aplicados a la industria hidroelectrica. La metodologia es una implantacion/ extension realizada por los autores de este trabajo, de los lineamientos propuestos por la Engineering Society for Advanced Mobility Land, Sea and Space en el estandar SAE-JA1012. Para contestar las primeras cinco preguntas del estandar se propone tomar como base los modos y mecanismos de fallas de componentes documentados en la guia para recopilar datos de falla en el estandar ISO-14224. Este enfoque permite estandarizar la descripcion de mecanismos de fallas de los equipos, tanto en el estudio RCM como en el proceso de recopilacion de datos de falla y de mantenimiento, lo que permite retroalimentar el ciclo de mejora continua de los procesos RCM. Tambien se propone el uso de matrices de riesgo para jerarquizar la importancia de los mecanismos de falla con base en el nivel de riesgo.

  7. 3D face recognition algorithm based on detecting reliable components

    Huang Wenjun; Zhou Xuebing; Niu Xiamu


    Fisherfaces algorithm is a popular method for face recognition. However, there exist some unstable components that degrade recognition performance. In this paper, we propose a method based on detecting reliable components to overcome the problem and introduce it to 3D face recognition. The reliable components are detected within the binary feature vector, which is generated from the Fisherfaces feature vector based on statistical properties, and is used for 3D face recognition as the final feature vector. Experimental results show that the reliable components feature vector is much more effective than the Fisherfaces feature vector for face recognition.

  8. Reliability Analysis of Dynamic Stability in Waves

    Søborg, Anders Veldt


    exhibit sufficient characteristics with respect to slope at zero heel (GM value), maximum leverarm, positive range of stability and area below the leverarm curve. The rule-based requirements to calm water leverarm curves are entirely based on experience obtained from vessels in operation and recorded......The assessment of a ship's intact stability is traditionally based on a semi-empirical deterministic concept that evaluates the characteristics of ship's calm water restoring leverarm curves. Today the ship is considered safe with respect to dynamic stability if its calm water leverarm curves...... accidents in the past. The rules therefore only leaves little room for evaluation and improvement of safety of a ship's dynamic stability. A few studies have evaluated the probability of ship stability loss in waves using Monte Carlo simulations. However, since this probability may be in the order of 10...

  9. Reliable Space Pursuing for Reliability-based Design Optimization with Black-box Performance Functions

    SHAN Songqing; WANG G Gary


    Reliability-based design optimization (RBDO) is intrinsically a double-loop procedure since it involves an overall optimization and an iterative reliability assessment at each search point. Due to the double-loop procedure, the computational expense of RBDO is normally very high. Current RBDO research focuses on problems with explicitly expressed performance functions and readily available gradients. This paper addresses a more challenging type of RBDO problem in which the performance functions are computation intensive. These computation intensive functions are often considered as a "black-box" and their gradients are not available or not reliable. On the basis of the reliable design space (RDS) concept proposed earlier by the authors, this paper proposes a Reliable Space Pursuing (RSP) approach, in which RDS is first identified and then gradually refined while optimization is performed. It fundamentally avoids the nested optimization and probabilistic assessment loop. Three well known RBDO problems from the literature are used for testing and demonstrating the effectiveness of the proposed RSP method.

  10. A Reliable SVD based Watermarking Schem

    Jain, Chirag; Panigrahi, Prasanta K


    We propose a novel scheme for watermarking of digital images based on singular value decomposition (SVD), which makes use of the fact that the SVD subspace preserves significant amount of information of an image, as compared to its singular value matrix, Zhang and Li (2005). The principal components of the watermark are embedded in the original image, leaving the detector with a complimentary set of singular vectors for watermark extraction. The above step invariably ensures that watermark extraction from the embedded watermark image, using a modified matrix, is not possible, thereby removing a major drawback of an earlier proposed algorithm by Liu and Tan (2002).

  11. Maritime shipping as a high reliability industry: A qualitative analysis

    Mannarelli, T.; Roberts, K.; Bea, R.


    The maritime oil shipping industry has great public demands for safe and reliable organizational performance. Researchers have identified a set of organizations and industries that operate at extremely high levels of reliability, and have labelled them High Reliability Organizations (HRO). Following the Exxon Valdez oil spill disaster of 1989, public demands for HRO-level operations were placed on the oil industry. It will be demonstrated that, despite enormous improvements in safety and reliability, maritime shipping is not operating as an HRO industry. An analysis of the organizational, environmental, and cultural history of the oil industry will help to provide justification and explanation. The oil industry will be contrasted with other HRO industries and the differences will inform the shortfalls maritime shipping experiences with regard to maximizing reliability. Finally, possible solutions for the achievement of HRO status will be offered.

  12. Reliability Analysis of OMEGA Network and Its Variants

    Suman Lata


    Full Text Available The performance of a computer system depends directly on the time required to perform a basic operation and the number of these basic operations that can be performed concurrently. High performance computing systems can be designed using parallel processing. Parallel processing is achieved by using more than one processors or computers together they communicate with each other to solve a givenproblem. MINs provide better way for the communication between different processors or memory modules with less complexity, fast communication, good fault tolerance, high reliability and low cost. Reliability of a system is the probability that it will successfully perform its intended operations for a given time under stated operating conditions. From the reliability analysis it has beenobserved that addition of one stage to Omega networks provide higher reliability in terms of terminal reliability than the addition of two stages in the corresponding network.

  13. Reliability-based Assessment of Fatigue Life for Bridges

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard


    The reliability level for bridges is discussed based on a comparison of the reliability levels proposed and used by e.g. JCSS, ISO, NKB and Eurocodes. The influence of reserve capacity by which failure of a specific detail does not lead to structural collapse is investigated. The results show...... of regular inspections into account. In an illustrative example the reliability level for a set of typical welded steel details is investigated along with the influence of different inspection methods. The results show that the reliability level can be significantly increased by applying regular inspections....... However, the accuracy of the inspection methods has a significant influence on how much the reliability level is increased by an inspection....

  14. Discrete event simulation versus conventional system reliability analysis approaches

    Kozine, Igor


    Discrete Event Simulation (DES) environments are rapidly developing and appear to be promising tools for building reliability and risk analysis models of safety-critical systems and human operators. If properly developed, they are an alternative to the conventional human reliability analysis models...... and systems analysis methods such as fault and event trees and Bayesian networks. As one part, the paper describes briefly the author’s experience in applying DES models to the analysis of safety-critical systems in different domains. The other part of the paper is devoted to comparing conventional approaches...

  15. Numerical Model based Reliability Estimation of Selective Laser Melting Process

    Mohanty, Sankhya; Hattel, Jesper Henri


    Selective laser melting is developing into a standard manufacturing technology with applications in various sectors. However, the process is still far from being at par with conventional processes such as welding and casting, the primary reason of which is the unreliability of the process. While...... of the selective laser melting process. A validated 3D finite-volume alternating-direction-implicit numerical technique is used to model the selective laser melting process, and is calibrated against results from single track formation experiments. Correlation coefficients are determined for process input...... parameters such as laser power, speed, beam profile, etc. Subsequently, uncertainties in the processing parameters are utilized to predict a range for the various outputs, using a Monte Carlo method based uncertainty analysis methodology, and the reliability of the process is established....

  16. Non-probabilistic fuzzy reliability analysis of pile foundation stability by interval theory


    Randomness and fuzziness are among the attributes of the influential factors for stability assessment of pile foundation.According to these two characteristics, the triangular fuzzy number analysis approach was introduced to determine the probability-distributed function of mechanical parameters. Then the functional function of reliability analysis was constructed based on the study of bearing mechanism of pile foundation, and the way to calculate interval values of the functional function was developed by using improved interval-truncation approach and operation rules of interval numbers. Afterwards, the non-probabilistic fuzzy reliability analysis method was applied to assessing the pile foundation, from which a method was presented for nonprobabilistic fuzzy reliability analysis of pile foundation stability by interval theory. Finally, the probability distribution curve of nonprobabilistic fuzzy reliability indexes of practical pile foundation was concluded. Its failure possibility is 0.91%, which shows that the pile foundation is stable and reliable.

  17. Structural Reliability Analysis for Implicit Performance with Legendre Orthogonal Neural Network Method

    Lirong Sha; Tongyu Wang


    In order to evaluate the failure probability of a complicated structure, the structural responses usually need to be estimated by some numerical analysis methods such as finite element method ( FEM) . The response surface method ( RSM) can be used to reduce the computational effort required for reliability analysis when the performance functions are implicit. However, the conventional RSM is time⁃consuming or cumbersome if the number of random variables is large. This paper proposes a Legendre orthogonal neural network ( LONN)⁃based RSM to estimate the structural reliability. In this method, the relationship between the random variables and structural responses is established by a LONN model. Then the LONN model is connected to a reliability analysis method, i.e. first⁃order reliability methods (FORM) to calculate the failure probability of the structure. Numerical examples show that the proposed approach is applicable to structural reliability analysis, as well as the structure with implicit performance functions.

  18. Cost effectiveness and reliability improvement capabilities of CHECWORKS and SWIPS based inspection and maintenance plans

    Singh, S. [United Dynamics, Malvern, PA (United States); Borodotsky, A. [Rochester Gas and Electric Corp., NY (United States)


    CHECWORKS and SWIPS are computer programs that undertaken degradation analysis and generate prioritized lists for scheduling inspections. A simplified analysis presented in this paper demonstrates that application of such computer aided degeneration analysis and prioritized list based I and M plans can achieve full system reliability along with high cost effectiveness. For purposes of developing insight and a basic understanding, relative cost-effectiveness and system reliability improvement analysis is conducted on a small service water system for five types of inspection and maintenance plans. The following plans are considered: a full inspection plan, a random sampling plan, an experienced based sampling plan, a computer aided degeneration analysis based plan, and a superman based plan. The results obtained show that a computer aided inspection plan is the most effective of the feasible plans. For a realistic system, the plan can pay for the analysis cost and generate additional cost savings while maintaining full system reliability.

  19. 基于改进CREAM的管制员与飞行员间人因可靠性分析%Human reliability analysis of the cooperative relation between the pilot and the controllers based on CREAM

    赵振武; 张微


    The present paper is inclined to introduce our study findings on the human reliability analysis of the alternative relation between the pilot and the controllers based on CREAM in air traffic and transportation. As is known, air traffic control is an alternative system between the air traffic controllers and the pilots, which reflects the air traffic control functions in the whole flight-operational and controlling process, with the controller s supervisory role in accordance with the flight conditions of the aircraft, and the controller' s command and supervision to the operation of the pilots to ensure the safety of the flight. As is known, human reliability analysis (HRA) focuses on the likely error and its probability of the process between human and system alternation. The idea of air traffic control implies that man is the key link in air traffic control. It is for this reason that human reliability is regarded as the key factor in the relation between the air traffic controllers and pilots. As a result of this study, full and complete reliability should be emphasized from the point of view of human trust on the traffic workers through the proper human reliability mode. Based on the combination with the alternation process between air traffic controller and pilot, human reliability model of the relation between the two sides can be established through the optimization of the Cognitive Reliability and Error Analysis Method ( CREAM) , which should be in turn carried out through the analysis of the alternative process between air traffic controllers and pilots and the modification to the comparison table of the cognitive behavior and cognitive function matrix in the CREAM. Thus, it is the human reliability in the alternative process that should be stressed by this model and the relative unsubstantial link should be ascertained by the comparison with the evaluation system of the standard indexes, which is also the team-performance factors of the air traffic

  20. A heuristic-based approach for reliability importance assessment of energy producers

    Akhavein, A., E-mail: [Department of Engineering, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Fotuhi Firuzabad, M., E-mail: fotuhi@sharif.ed [Department of Electrical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)


    Reliability of energy supply is one of the most important issues of service quality. On one hand, customers usually have different expectations for service reliability and price. On the other hand, providing different level of reliability at load points is a challenge for system operators. In order to take reasonable decisions and obviate reliability implementation difficulties, market players need to know impacts of their assets on system and load-point reliabilities. One tool to specify reliability impacts of assets is the criticality or reliability importance measure by which system components can be ranked based on their effect on reliability. Conventional methods for determination of reliability importance are essentially on the basis of risk sensitivity analysis and hence, impose prohibitive calculation burden in large power systems. An approach is proposed in this paper to determine reliability importance of energy producers from perspective of consumers or distribution companies in a composite generation and transmission system. In the presented method, while avoiding immense computational burden, the energy producers are ranked based on their rating, unavailability and impact on power flows in the lines connecting to the considered load points. Study results on the IEEE reliability test system show successful application of the proposed method. - Research highlights: {yields} Required reliability level at load points is a concern in modern power systems. {yields} It is important to assess reliability importance of energy producers or generators. {yields} Generators can be ranked based on their impacts on power flow to a selected area. {yields} Ranking of generators is an efficient tool to assess their reliability importance.

  1. Seismic reliability analysis of urban water distribution network

    Li Jie; Wei Shulin; Liu Wei


    An approach to analyze the seismic reliability of water distribution networks by combining a hydraulic analysis with a first-order reliability method (FORM), is proposed in this paper.The hydraulic analysis method for normal conditions is modified to accommodate the special conditions necessary to perform a seismic hydraulic analysis. In order to calculate the leakage area and leaking flow of the pipelines in the hydraulic analysis method, a new leakage model established from the seismic response analysis of buried pipelines is presented. To validate the proposed approach, a network with 17 nodes and 24 pipelines is investigated in detail. The approach is also applied to an actual project consisting of 463 nodes and 767pipelines. Thee results show that the proposed approach achieves satisfactory results in analyzing the seismic reliability of large-scale water distribution networks.


    M. Khalaj


    Full Text Available

    ENGLISH ABSTRACT: The overall objective of the reliability allocation is to increase the profitability of the operation and optimise the total life cycle cost without losses from failure issues. The methodology, called risk-based reliability (RBR, is based on integrating a reliability approach and a risk assessment strategy to obtain an optimum cost and acceptable risk. This assessment integrates reliability with the smaller losses from failures issues, and so can be used as a tool for decision-making. The approach to maximising reliability should be replaced with the risk-based reliability assessment approach, in which reliability planning, based on risk analysis, minimises the probability of system failure and its consequences. This paper proposes a new methodology for risk-based reliability under epistemic uncertainty, using possibility theory and probability theory. This methodology is used for a case study in order to determine the reliability and risk of production systems when the available data are insufficient, and to help make decisions.

    AFRIKAANSE OPSOMMING: Die hoofdoelwit van betroubaarheidstoedeling is die verhoging van winsgewendheid van sisteemgebruik teen die agtergrond van optimum totale leeftydsikluskoste. Die metodologie genaamd “risikogebaseerde betroubaarheid” behels die bepaling van ’n risikoskatting om optimum koste te behaal vir ’n aanvaarbare risiko. Die navorsing stel vervolgens ’n nuwe ontledingsmetode voor vir epistemiese onsekerheid gebaseer op moontlikheids- en waarskynlikheidsleer. ’n Bypassende gevallestudie word aangebied.


    Ronald L. Boring; Donald D. Dudenhoeffer; Bruce P. Hallbert; Brian F. Gore


    This paper summarizes an emerging collaboration between Idaho National Laboratory and NASA Ames Research Center regarding the utilization of high-fidelity MIDAS simulations for modeling control room crew performance at nuclear power plants. The key envisioned uses for MIDAS-based control room simulations are: (i) the estimation of human error with novel control room equipment and configurations, (ii) the investigative determination of risk significance in recreating past event scenarios involving control room operating crews, and (iii) the certification of novel staffing levels in control rooms. It is proposed that MIDAS serves as a key component for the effective modeling of risk in next generation control rooms.

  4. Reliability Analysis and Modeling of ZigBee Networks

    Lin, Cheng-Min

    The architecture of ZigBee networks focuses on developing low-cost, low-speed ubiquitous communication between devices. The ZigBee technique is based on IEEE 802.15.4, which specifies the physical layer and medium access control (MAC) for a low rate wireless personal area network (LR-WPAN). Currently, numerous wireless sensor networks have adapted the ZigBee open standard to develop various services to promote improved communication quality in our daily lives. The problem of system and network reliability in providing stable services has become more important because these services will be stopped if the system and network reliability is unstable. The ZigBee standard has three kinds of networks; star, tree and mesh. The paper models the ZigBee protocol stack from the physical layer to the application layer and analyzes these layer reliability and mean time to failure (MTTF). Channel resource usage, device role, network topology and application objects are used to evaluate reliability in the physical, medium access control, network, and application layers, respectively. In the star or tree networks, a series system and the reliability block diagram (RBD) technique can be used to solve their reliability problem. However, a division technology is applied here to overcome the problem because the network complexity is higher than that of the others. A mesh network using division technology is classified into several non-reducible series systems and edge parallel systems. Hence, the reliability of mesh networks is easily solved using series-parallel systems through our proposed scheme. The numerical results demonstrate that the reliability will increase for mesh networks when the number of edges in parallel systems increases while the reliability quickly drops when the number of edges and the number of nodes increase for all three networks. More use of resources is another factor impact on reliability decreasing. However, lower network reliability will occur due to

  5. Reliability-based design optimization of multiphysics, aerospace systems

    Allen, Matthew R.

    Aerospace systems are inherently plagued by uncertainties in their design, fabrication, and operation. Safety factors and expensive testing at the prototype level traditionally account for these uncertainties. Reliability-based design optimization (RBDO) can drastically decrease life-cycle development costs by accounting for the stochastic nature of the system response in the design process. The reduction in cost is amplified for conceptually new designs, for which no accepted safety factors currently exist. Aerospace systems often operate in environments dominated by multiphysics phenomena, such as the fluid-structure interaction of aeroelastic wings or the electrostatic-mechanical interaction of sensors and actuators. The analysis of such phenomena is generally complex and computationally expensive, and therefore is usually simplified or approximated in the design process. However, this leads to significant epistemic uncertainties in modeling, which may dominate the uncertainties for which the reliability analysis was intended. Therefore, the goal of this thesis is to present a RBDO framework that utilizes high-fidelity simulation techniques to minimize the modeling error for multiphysics phenomena. A key component of the framework is an extended reduced order modeling (EROM) technique that can analyze various states in the design or uncertainty parameter space at a reduced computational cost, while retaining characteristics of high-fidelity methods. The computational framework is verified and applied to the RBDO of aeroelastic systems and electrostatically driven sensors and actuators, utilizing steady-state analysis and design criteria. The framework is also applied to the design of electrostatic devices with transient criteria, which requires the use of the EROM technique to overcome the computational burden of multiple transient analyses.


    E. Vidya Sagar


    Full Text Available Power reliability and quality are gaining their greater grounds than ever in the power and industrial market of the times. It has become an essential means for the successful dispatch of quality product, operation, services of any industry. The reliability of power distribution network can be greatly enhanced by the automation of its feeder system and other associated parts. Remotely controlled and automated restoration services can avoid the necessity of executing manual switching schedules and are bound to bring about remarkable levels of system reliability and interruption costs. The reliability cost-worth analysis is the excellent tool for evaluation of interruption costs. Reliability cost-worth analysis is very significant in the power system planning, operation, maintenance andexpansion, for it takes into account the customer concerns in the analysis. This paper deals in due detail with the reliability based cost-worth analysis of automated radial distribution network. The direct method of assessing the worth of reliability is to calculate the user costs relevant to interruptions in the power supply. By the application of failure mode effect analysis and cost-worth analysis byusing direct costing method the reliability of radial distribution network can be evaluated. The customer interruption costs’ indices of a radial distribution network calculated using the analytical method applied to an Indian utility network system with 2000KVA& sixteen nodes and the related results of the study are duly discussed in this paper.


    Su Xihong; Liu Hongwei; Wu Zhibo; Yang Xiaozong; Zuo Decheng


    Reliability is one of the most critical properties of software system.System deployment architecture is the allocation of system software components on host nodes.Software Architecture (SA)based software deployment models help to analyze reliability of different deployments.Though many approaches for architecture-based reliability estimation exist,little work has incorporated the influence of system deployment and hardware resources into reliability estimation.There are many factors influencing system deployment.By translating the multi-dimension factors into degree matrix of component dependence,we provide the definition of component dependence and propose a method of calculating system reliability of deployments.Additionally,the parameters that influence the optimal deployment may change during system execution.The existing software deployment architecture may be ill-suited for the given environment,and the system needs to be redeployed to improve reliability.An approximate algorithm,A*_D,to increase system reliability is presented.When the number of components and host nodes is relative large,experimental results show that this algorithm can obtain better deployment than stochastic and greedy algorithms.

  8. Reliability Analysis of Structural Timber Systems

    Sørensen, John Dalsgaard; Hoffmeyer, P.


    characteristics of the load-bearing capacity is estimated in the form of a characteristic value and a coefficient of variation. These two values are of primary importance for codes of practice based on the partial safety factor format since the partial safety factor is closely related to the coefficient...... the above stochastic models, statistical characteristics (distribution function, 5% quantile and coefficient of variation) are determined. Generally, the results show that taking the system effects into account the characteristic load bearing capacity can be increased and the partial safety factor decreased...... of variation. In the paper a stochastic model is described for the strength of a single piece of timber taking into account the stochastic variation of the strength and stiffness with length. Also stochastic models for different types of loads are formulated. First, simple representative systems with different...

  9. Test-Retest Reliability and Concurrent Validity of a Single Tri-Axial Accelerometer-Based Gait Analysis in Older Adults with Normal Cognition.

    Seonjeong Byun

    Full Text Available We investigated the concurrent validity and test-retest reliability of spatio-temporal gait parameters measured with a single tri-axial accelerometer (TAA, determined the optimal number of steps required for obtaining acceptable levels of reliability, and compared the validity and reliability of the estimated gait parameters across the three reference axes of the TAA.A total of 82 cognitively normal elderly participants walked around a 40-m long round walkway twice wearing a TAA at their center of body mass. Gait parameters such as cadence, gait velocity, step time, step length, step time variability, and step time asymmetry were estimated from the low pass-filtered signal of the TAA. The test-retest reliability and concurrent validity with the GAITRite® system were evaluated for the estimated gait parameters.Gait parameters using signals from the vertical axis showed excellent reliability for all gait parameters; the intraclass correlation coefficient (ICC was 0.79-0.90. A minimum of 26 steps and 14 steps were needed to achieve excellent reliability in step time variability and step time asymmetry, respectively. A strong level of agreement was seen for the basic gait parameters between the TAA and GAITRiteⓇ (ICC = 0.91-0.96.The measurement of gait parameters of elderly individuals with normal cognition using a TAA placed on the body's center of mass was reliable and showed superiority over the GAITRiteⓇ with regard to gait variability and asymmetry. The TAA system was a valid tool for measuring basic gait parameters. Considering its wearability and low price, the TAA system may be a promising alternative to the pressure sensor walkway system for measuring gait parameters.

  10. Sequential optimization and reliability assessment based on dimension reduction method for accurate and efficient reliability-based design optimization

    Lim, Jong Min; Lee, Byung Chai; Lee, Ik Jin [KAIST, Daejeon (Korea, Republic of)


    This study develops an efficient and accurate methodology for reliability-based design optimization (RBDO) by combining the most probable point (MPP)-based dimension reduction method (DRM) to enhance accuracy and the sequential optimization and reliability assessment (SORA) to enhance efficiency. In many researches, first-order reliability method (FORM) has been utilized for RBDO methods due to its efficiency and simplicity. However, it might not be accurate enough for highly nonlinear performance functions. Therefore, the MPP-based DRM is introduced for the accurate reliability assessment in this study. Even though the MPP-based DRM significantly improves the accuracy, additional computations for the moment-based integration are required. It is desirable to reduce the number of reliability analyses in the RBDO process. Since decoupled approaches such as SORA reduce necessary reliability analyses considerably, DRM-based SORA is proposed in this study for accurate and efficient RBDO. Furthermore, convex linearization is introduced to approximate inactive probabilistic constraints to additionally improve the efficiency. The efficiency and accuracy of the proposed method are verified through numerical examples.

  11. Analysis on Operation Reliability of Generating Units in 2009



    This paper presents the data on operation reliability indices and relevant analyses toward China's conventional power generating units in 2009. The units brought into the statistical analysis include 100-MW or above thermal generating units, 40-MW or above hydro generating units, and all nuclear generating units. The reliability indices embodied include utilization hours, times and hours of scheduled outages, times and hours of unscheduled outages, equivalent forced outage rate and equivalent availability factor.

  12. Reliability Analysis of Metallized Film Pulse Capacitors under Competing Failure Modes Based on Regression Analysis%基于参数回归分析的金属化膜脉冲电容器竞争失效分析

    刘芳; 赵建印; 彭绍雄


    The failures of metallized-film capacitor have two modes:traumatic and degradation failures. By analyzing degradation mechanism of metallized-film capacitor, a general model under competing failure modes involving both traumatic and degradation failures is given based on parameter regression analysis, and used to analyze the test data of some capacitors. According to the assessment results, the reliability probability of the capacitors is 0. 7986 for 10 000 shots. This model provides an effective method to assess the reliability of electronic products under competing failures modes.%金属化膜脉冲电容器既有突发型失效又有退化型失效.通过分析金属化膜脉冲电容器的退化失效机理,在假设突发失效与退化失效相关的条件下,给出了基于参数回归分析的电容器竞争失效的一般模型,最后利用该模型对某金属化膜脉冲电容器的试验数据进行可靠性分析.根据评估结论,该电容器打靶10 000发的可靠度为0.798 6.该模型为竞争失效模式下电子产品可靠性评估提供了一种新的有效途径.

  13. Acquisition and statistical analysis of reliability data for I and C parts in plant protection system

    Lim, T. J.; Byun, S. S.; Han, S. H.; Lee, H. J.; Lim, J. S.; Oh, S. J.; Park, K. Y.; Song, H. S. [Soongsil Univ., Seoul (Korea)


    This project has been performed in order to construct I and C part reliability databases for detailed analysis of plant protection system and to develop a methodology for analysing trip set point drifts. Reliability database for the I and C parts of plant protection system is required to perform the detailed analysis. First, we have developed an electronic part reliability prediction code based on MIL-HDBK-217F. Then we have collected generic reliability data for the I and C parts in plant protection system. Statistical analysis procedure has been developed to process the data. Then the generic reliability database has been constructed. We have also collected plant specific reliability data for the I and C parts in plant protection system for YGN 3,4 and UCN 3,4 units. Plant specific reliability database for I and C parts has been developed by the Bayesian procedure. We have also developed an statistical analysis procedure for set point drift, and performed analysis of drift effects for trip set point. The basis for the detailed analysis can be provided from the reliability database for the PPS I and C parts. The safety of the KSNP and succeeding NPPs can be proved by reducing the uncertainty of PSA. Economic and efficient operation of NPP can be possible by optimizing the test period to reduce utility's burden. 14 refs., 215 figs., 137 tabs. (Author)

  14. Risk and reliability analysis theory and applications : in honor of Prof. Armen Der Kiureghian


    This book presents a unique collection of contributions from some of the foremost scholars in the field of risk and reliability analysis. Combining the most advanced analysis techniques with practical applications, it is one of the most comprehensive and up-to-date books available on risk-based engineering. All the fundamental concepts needed to conduct risk and reliability assessments are covered in detail, providing readers with a sound understanding of the field and making the book a powerful tool for students and researchers alike. This book was prepared in honor of Professor Armen Der Kiureghian, one of the fathers of modern risk and reliability analysis.

  15. Reliability-based design optimization with Cross-Entropy method

    Ghidey, Hiruy


    Implementation of the Cross-entropy (CE) method to solve reliability-based design optimization (RBDO) problems was investigated. The emphasis of this implementation method was to solve independently both the reliability and optimization sub-problems within the RBDO problem; therefore, the main aim of this study was to evaluate the performance of the Cross-entropy method in terms of efficiency and accuracy to solve RBDO problems. A numerical approach was followed in which the implementatio...

  16. Reliability based design optimization using akaike information criterion for discrete information

    Lim, Woochul; Lee, Tae Hee [Hanyang Univ., Seoul (Korea, Republic of)


    Reliability based design optimization (RBDO) can be used to determine the reliability of a system by means of probabilistic design criteria, i.e., the possibility of failure considering stochastic features of design variables and input parameters. To assure these criteria, various reliability analysis methods have been developed. Most of these methods assume that distribution functions are continuous. However, in real problems, because real data is often discrete in form, it is important to estimate the distributions for discrete information during reliability analysis. In this study, we employ the Akaike information criterion (AIC) method for reliability analysis to determine the best estimated distribution for discrete information and we suggest an RBDO method using AIC. Mathematical and engineering examples are illustrated to verify the proposed method.

  17. Reliability Modeling and Optimization Strategy for Manufacturing System Based on RQR Chain

    Yihai He


    Full Text Available Accurate and dynamic reliability modeling for the running manufacturing system is the prerequisite to implement preventive maintenance. However, existing studies could not output the reliability value in real time because their abandonment of the quality inspection data originated in the operation process of manufacturing system. Therefore, this paper presents an approach to model the manufacturing system reliability dynamically based on their operation data of process quality and output data of product reliability. Firstly, on the basis of importance explanation of the quality variations in manufacturing process as the linkage for the manufacturing system reliability and product inherent reliability, the RQR chain which could represent the relationships between them is put forward, and the product qualified probability is proposed to quantify the impacts of quality variation in manufacturing process on the reliability of manufacturing system further. Secondly, the impact of qualified probability on the product inherent reliability is expounded, and the modeling approach of manufacturing system reliability based on the qualified probability is presented. Thirdly, the preventive maintenance optimization strategy for manufacturing system driven by the loss of manufacturing quality variation is proposed. Finally, the validity of the proposed approach is verified by the reliability analysis and optimization example of engine cover manufacturing system.

  18. Reliability analysis of flood defence systems in the Netherlands

    Lassing, B.L.; Vrouwenvelder, A.C.W.M.; Waarts, P.H.


    In recent years an advanced program for reliability analysis of dike systems has been under de-velopment in the Netherlands. This paper describes the global data requirements for application and the set-up of the models in the Netherlands. The analysis generates an estimate of the probability of sys

  19. 基于Petri网的井下煤仓可靠性分析%Analysis of Bunker Reliability Based on Petri Nets

    王毅; 刘志河; 李剑刚


    采用Petri网原理,针对矿井运输系统中柔性部件——煤仓,建立其Petri网模型,并通过随机过程理论计算了煤仓的有效度,从而给出了计算煤仓有效度的一个新的方法。%Petri nets is a new way in calculating bunker availability. The author designs petri nets model and analyses reliability of flexible units (i.e bunker) of mining transport system.Petri nets model with reliability theory model is presented.

  20. Grid weak point analysis based on loop contribution index of the reliability%基于回路可靠性贡献指标的电网薄弱点分析

    肖雅元; 张磊; 罗毅; 王宏刚; 邓集


    Power system’s weak point analysis commonly uses sensitivity analysis method. This paper presents a new identification method of weak points based on loop bulk power system reliability of adequacy evaluation. The method puts the loop reliability parameters as input parameters to assess the reliability of the bulk power system, and determines the important degree of circuit elements based on Birnbaum constant method. To better distinguish the weak point in the system, this paper deduces loop contribution indices on the basis of the traditional grid system reliability evaluation indices. The system-loops-node three levels reflect the reliability of the electrical network and weak points. The actual assessment of province's power grid indicates that the method can effectively reduce the number of system status without complex sensitivity calculation, and overcome the problem that the traditional system reliability index can’t accurately find the weak points.%电网薄弱点分析通常采用灵敏度分析方法。提出了一种基于回路的大电网可靠性充裕度评估的薄弱点辨识新方法。该方法采用回路可靠性参数作为电网可靠性评估的输入参数,结合Birnbaum恒定方法确定回路中元件的重要度。为更好地区分系统中的薄弱点,在传统电网可靠性评估系统指标的基础上,推导出了回路贡献指标,从系统-回路-节点三个层面反映了电网的可靠性情况及薄弱环节。对某省实际电网的评估结果表明,该方法不用进行复杂的灵敏度计算且有效减少系统状态数量,克服了传统可靠性指标无法准确找到系统薄弱点的问题。

  1. Operation of Reliability Analysis Center (FY85-87)


    environmental conditions at the time of the reported failure as well as the exact nature of the failure. 4 The diskette format (FMDR-21A) contains...based upon the reliability and maintainability standards and tasks delineated in NAC R&M-STD-ROO010 (Reliability Program Requirements Seleccion ). These...characteristics, environmental conditions at the time of the reported failure, and the exact nature of the failure, which has been categorized as follows

  2. Recent advances in computational structural reliability analysis methods

    Thacker, Ben H.; Wu, Y.-T.; Millwater, Harry R.; Torng, Tony Y.; Riha, David S.


    The goal of structural reliability analysis is to determine the probability that the structure will adequately perform its intended function when operating under the given environmental conditions. Thus, the notion of reliability admits the possibility of failure. Given the fact that many different modes of failure are usually possible, achievement of this goal is a formidable task, especially for large, complex structural systems. The traditional (deterministic) design methodology attempts to assure reliability by the application of safety factors and conservative assumptions. However, the safety factor approach lacks a quantitative basis in that the level of reliability is never known and usually results in overly conservative designs because of compounding conservatisms. Furthermore, problem parameters that control the reliability are not identified, nor their importance evaluated. A summary of recent advances in computational structural reliability assessment is presented. A significant level of activity in the research and development community was seen recently, much of which was directed towards the prediction of failure probabilities for single mode failures. The focus is to present some early results and demonstrations of advanced reliability methods applied to structural system problems. This includes structures that can fail as a result of multiple component failures (e.g., a redundant truss), or structural components that may fail due to multiple interacting failure modes (e.g., excessive deflection, resonate vibration, or creep rupture). From these results, some observations and recommendations are made with regard to future research needs.

  3. On reliability analysis of multi-categorical forecasts

    J. Bröcker


    Full Text Available Reliability analysis of probabilistic forecasts, in particular through the rank histogram or Talagrand diagram, is revisited. Two shortcomings are pointed out: Firstly, a uniform rank histogram is but a necessary condition for reliability. Secondly, if the forecast is assumed to be reliable, an indication is needed how far a histogram is expected to deviate from uniformity merely due to randomness. Concerning the first shortcoming, it is suggested that forecasts be grouped or stratified along suitable criteria, and that reliability is analyzed individually for each forecast stratum. A reliable forecast should have uniform histograms for all individual forecast strata, not only for all forecasts as a whole. As to the second shortcoming, instead of the observed frequencies, the probability of the observed frequency is plotted, providing and indication of the likelihood of the result under the hypothesis that the forecast is reliable. Furthermore, a Goodness-Of-Fit statistic is discussed which is essentially the reliability term of the Ignorance score. The discussed tools are applied to medium range forecasts for 2 m-temperature anomalies at several locations and lead times. The forecasts are stratified along the expected ranked probability score. Those forecasts which feature a high expected score turn out to be particularly unreliable.

  4. Reliability-Based Design of Wind Turbine Components

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard


    wind turbine design a deterministic design approach based on partial safety factors is normally used. In the present paper a numerical example demonstrates how information from tests with wind turbine blades can be used to establish a probabilistic basis for reliabilitybased design. It is also......Application of reliability-based design for wind turbines requires a definition of the probabilistic basis for the individual components of the wind turbine. In the present paper reliability-based design of structural wind turbine components is considered. A framework for the uncertainties which...... demonstrated how partial safety factors can be derived for reliability-based design and how the partial safety factors changes dependent on the uncertainty in the test results....

  5. Research on Control Method Based on Real-Time Operational Reliability Evaluation for Space Manipulator

    Yifan Wang


    Full Text Available A control method based on real-time operational reliability evaluation for space manipulator is presented for improving the success rate of a manipulator during the execution of a task. In this paper, a method for quantitative analysis of operational reliability is given when manipulator is executing a specified task; then a control model which could control the quantitative operational reliability is built. First, the control process is described by using a state space equation. Second, process parameters are estimated in real time using Bayesian method. Third, the expression of the system's real-time operational reliability is deduced based on the state space equation and process parameters which are estimated using Bayesian method. Finally, a control variable regulation strategy which considers the cost of control is given based on the Theory of Statistical Process Control. It is shown via simulations that this method effectively improves the operational reliability of space manipulator control system.

  6. Multi-Objective Fuzzy Optimum Design Based on Reliability for Offshore Jacket Platforms

    康海贵; 刘未; 翟钢军; 徐发淙; 封盛


    In consideration of the fuzzy constraint boundary and through analysis of structural reliability, a model of structural fuzzy optimum design is established based on reliability for offshore jacket platforms. According to the characteristics of offshore jacket platforms, the tolerance coefficient of the constraint boundary is determined with the fuzzy optimization method. The optimum level cut set λ *, which is the intersection of the fuzzy constraint set and fuzzy objective set, is determined with the bound search method, and then the fuzzy optimum solution to the fuzzy optimization problem is obtained. The central offshore platform SZ36-1 is designed with the fuzzy optimum model based on reliability; the results are compared with those from deterministic optimum design and fuzzy optimum design. The tendency of design variables in the above three methods and its reasons are analyzed. The results of an example show that the fuzzy optimum design based on reliability is stable and reliable.

  7. Reliability-based design for automobiles in China

    Yimin ZHANG


    The level of automobile design and manufac-turing is an important sign of leadership in science and technology and economic power. The achievements of theories and methods for reliability-based design of auto-mobiles in China are reviewed. For reliability-based design, the theories and practices, optimization, sensitiv-ity, and robustness are estimated. The techniques of reli-ability-based design for automobiles are developed. The techniques service to the "hollow" phenomena of kernel technology, product innovative power, and independent development power can be solved.

  8. The development of a reliable amateur boxing performance analysis template.

    Thomson, Edward; Lamb, Kevin; Nicholas, Ceri


    The aim of this study was to devise a valid performance analysis system for the assessment of the movement characteristics associated with competitive amateur boxing and assess its reliability using analysts of varying experience of the sport and performance analysis. Key performance indicators to characterise the demands of an amateur contest (offensive, defensive and feinting) were developed and notated using a computerised notational analysis system. Data were subjected to intra- and inter-observer reliability assessment using median sign tests and calculating the proportion of agreement within predetermined limits of error. For all performance indicators, intra-observer reliability revealed non-significant differences between observations (P > 0.05) and high agreement was established (80-100%) regardless of whether exact or the reference value of ±1 was applied. Inter-observer reliability was less impressive for both analysts (amateur boxer and experienced analyst), with the proportion of agreement ranging from 33-100%. Nonetheless, there was no systematic bias between observations for any indicator (P > 0.05), and the proportion of agreement within the reference range (±1) was 100%. A reliable performance analysis template has been developed for the assessment of amateur boxing performance and is available for use by researchers, coaches and athletes to classify and quantify the movement characteristics of amateur boxing.

  9. Stochastic Finite Elements in Reliability-Based Structural Optimization

    Sørensen, John Dalsgaard; Engelund, S.


    Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to optimi......Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect...

  10. Stochastic Finite Elements in Reliability-Based Structural Optimization

    Sørensen, John Dalsgaard; Engelund, S.

    Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to optimi......Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect...

  11. Reliability Analysis of Wireless Sensor Networks Using Markovian Model

    Jin Zhu


    Full Text Available This paper investigates reliability analysis of wireless sensor networks whose topology is switching among possible connections which are governed by a Markovian chain. We give the quantized relations between network topology, data acquisition rate, nodes' calculation ability, and network reliability. By applying Lyapunov method, sufficient conditions of network reliability are proposed for such topology switching networks with constant or varying data acquisition rate. With the conditions satisfied, the quantity of data transported over wireless network node will not exceed node capacity such that reliability is ensured. Our theoretical work helps to provide a deeper understanding of real-world wireless sensor networks, which may find its application in the fields of network design and topology control.

  12. Decomposition Techniques and Effective Algorithms in Reliability-Based Optimization

    Enevoldsen, I.; Sørensen, John Dalsgaard


    The common problem of an extensive number of limit state function calculations in the various formulations and applications of reliability-based optimization is treated. It is suggested to use a formulation based on decomposition techniques so the nested two-level optimization problem can be solved...

  13. Reliability Analysis of the Digital Reactor Protection System Based on RBD Method%基于 RBD 方法的数字化反应堆保护系统可靠性分析



    It presents system availability and failure rate analysis and calculation methodology for reactor trip and Engineered Safety Feature Actuation as object for Reactor Protection System (RPS) in a native Nuclear power plant.This reliability analysis is based on RPS architecture and adopts the analysis methodology of Reliability Block Diagram.The results meet to the general design requirements of the nuclear power plant , and provide the important theory bases and the data supports to optimize RPS system architecture design and analyze the reliabil -ity of the nuclear power plant .%以国内某一核电厂数字化反应堆保护系统的架构为基础,反应堆停堆和专设安全设施驱动功能为对象,采用可靠性方框图分析方法,对反应堆保护系统的可用性和系统故障率进行分析和计算,结果表明满足核电厂系统总体设计要求,并为优化反应堆保护系统架构设计和核电厂可靠性分析提供了重要理论依据和数据支撑。

  14. Reliability-based condition assessment of steel containment and liners

    Ellingwood, B.; Bhattacharya, B.; Zheng, R. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering


    Steel containments and liners in nuclear power plants may be exposed to aggressive environments that may cause their strength and stiffness to decrease during the plant service life. Among the factors recognized as having the potential to cause structural deterioration are uniform, pitting or crevice corrosion; fatigue, including crack initiation and propagation to fracture; elevated temperature; and irradiation. The evaluation of steel containments and liners for continued service must provide assurance that they are able to withstand future extreme loads during the service period with a level of reliability that is sufficient for public safety. Rational methodologies to provide such assurances can be developed using modern structural reliability analysis principles that take uncertainties in loading, strength, and degradation resulting from environmental factors into account. The research described in this report is in support of the Steel Containments and Liners Program being conducted for the US Nuclear Regulatory Commission by the Oak Ridge National Laboratory. The research demonstrates the feasibility of using reliability analysis as a tool for performing condition assessments and service life predictions of steel containments and liners. Mathematical models that describe time-dependent changes in steel due to aggressive environmental factors are identified, and statistical data supporting the use of these models in time-dependent reliability analysis are summarized. The analysis of steel containment fragility is described, and simple illustrations of the impact on reliability of structural degradation are provided. The role of nondestructive evaluation in time-dependent reliability analysis, both in terms of defect detection and sizing, is examined. A Markov model provides a tool for accounting for time-dependent changes in damage condition of a structural component or system. 151 refs.


    Nichols, R.


    Recent analysis of offshore wind turbine foundations using both applicable API and IEC standards show that the total load demand from wind and waves is greatest in wave driven storms. Further, analysis of overturning moment loads (OTM) reveal that impact forces exerted by breaking waves are the largest contributor to OTM in big storms at wind speeds above the operating range of 25 m/s. Currently, no codes or standards for offshore wind power generators have been adopted by the Bureau of Ocean Energy Management Regulation and Enforcement (BOEMRE) for use on the Outer Continental Shelf (OCS). Current design methods based on allowable stress design (ASD) incorporate the uncertainty in the variation of loads transferred to the foundation and geotechnical capacity of the soil and rock to support the loads is incorporated into a factor of safety. Sources of uncertainty include spatial and temporal variation of engineering properties, reliability of property measurements applicability and sufficiency of sampling and testing methods, modeling errors, and variability of estimated load predictions. In ASD these sources of variability are generally given qualitative rather than quantitative consideration. The IEC 61400‐3 design standard for offshore wind turbines is based on ASD methods. Load and resistance factor design (LRFD) methods are being increasingly used in the design of structures. Uncertainties such as those listed above can be included quantitatively into the LRFD process. In LRFD load factors and resistance factors are statistically based. This type of analysis recognizes that there is always some probability of failure and enables the probability of failure to be quantified. This paper presents an integrated approach consisting of field observations and numerical simulation to establish the distribution of loads from breaking waves to support the LRFD of fixed offshore foundations.

  16. Statistical models and methods for reliability and survival analysis

    Couallier, Vincent; Huber-Carol, Catherine; Mesbah, Mounir; Huber -Carol, Catherine; Limnios, Nikolaos; Gerville-Reache, Leo


    Statistical Models and Methods for Reliability and Survival Analysis brings together contributions by specialists in statistical theory as they discuss their applications providing up-to-date developments in methods used in survival analysis, statistical goodness of fit, stochastic processes for system reliability, amongst others. Many of these are related to the work of Professor M. Nikulin in statistics over the past 30 years. The authors gather together various contributions with a broad array of techniques and results, divided into three parts - Statistical Models and Methods, Statistical

  17. Bayesian Inference for NASA Probabilistic Risk and Reliability Analysis

    Dezfuli, Homayoon; Kelly, Dana; Smith, Curtis; Vedros, Kurt; Galyean, William


    This document, Bayesian Inference for NASA Probabilistic Risk and Reliability Analysis, is intended to provide guidelines for the collection and evaluation of risk and reliability-related data. It is aimed at scientists and engineers familiar with risk and reliability methods and provides a hands-on approach to the investigation and application of a variety of risk and reliability data assessment methods, tools, and techniques. This document provides both: A broad perspective on data analysis collection and evaluation issues. A narrow focus on the methods to implement a comprehensive information repository. The topics addressed herein cover the fundamentals of how data and information are to be used in risk and reliability analysis models and their potential role in decision making. Understanding these topics is essential to attaining a risk informed decision making environment that is being sought by NASA requirements and procedures such as 8000.4 (Agency Risk Management Procedural Requirements), NPR 8705.05 (Probabilistic Risk Assessment Procedures for NASA Programs and Projects), and the System Safety requirements of NPR 8715.3 (NASA General Safety Program Requirements).

  18. Notes on numerical reliability of several statistical analysis programs

    Landwehr, J.M.; Tasker, Gary D.


    This report presents a benchmark analysis of several statistical analysis programs currently in use in the USGS. The benchmark consists of a comparison between the values provided by a statistical analysis program for variables in the reference data set ANASTY and their known or calculated theoretical values. The ANASTY data set is an amendment of the Wilkinson NASTY data set that has been used in the statistical literature to assess the reliability (computational correctness) of calculated analytical results.

  19. A level set method for reliability-based topology optimization of compliant mechanisms


    Based on the level set model and the reliability theory, a numerical approach of reliability-based topology optimization for compliant mechanisms with multiple inputs and outputs is presented. A multi-objective topology optimal model of compliant mechanisms considering uncertainties of the loads, material properties, and member geometries is developed. The reliability analysis and topology optimization are integrated in the optimal iterative process. The reliabilities of the compliant mechanisms are evaluated by using the first order reliability method. Meanwhile, the problem of structural topology optimization is solved by the level set method which is flexible in handling complex topological changes and concise in describing the boundary shape of the mechanism. Numerical examples show the importance of considering the stochastic nature of the compliant mechanisms in the topology optimization process.

  20. Reliable design space and complete single-loop reliability-based design optimization

    Shan Songqing [University of Manitoba (Canada); Wang, G. Gary [University of Manitoba (Canada)], E-mail:


    Reliability-based design optimization (RBDO) has been intensively studied due to its significance and its conceptual and mathematical complexity. This paper proposes a new method for RBDO on the basis of the concept of reliable design space (RDS), within which any design satisfies the reliability requirements. Therefore, a RBDO problem becomes a simple, deterministic optimization problem constrained by RDS rather than its deterministic feasible space. The RDS is found in this work by using the partial derivatives at the current design point as an approximation of the derivatives at its corresponding most probable point (MPP) on the limit state function. This work completely resolves the double loop in RBDO and turns RBDO into a simple optimization problem. Well-known problems from the literature are selected to illustrate the steps of the approach and for result comparison. Discussions will also be given on the limitation of the proposed method, which is shown to be a common limitation overlooked by the research community on RBDO.

  1. Failure Analysis towards Reliable Performance of Aero-Engines

    T. Jayakumar


    Full Text Available Aero-engines are critical components whose reliable performance decides the primary safety of anaircrafthelicopter. This is met by rigorous maintenance schedule with periodic inspection/nondestructive testingof various engine components. In spite of these measures, failure of areo-engines do occur rather frequentlyin comparison to failure of other components. Systematic failure analysis helps one to identify root causeof the failure, thus enabling remedial measures to prevent recurrence of such failures. Turbine blades madeof nickel or cobalt-based alloys are used in aero-engines. These blades are subjected to complex loadingconditions at elevated temperatures. The main causes of failure of blades are attributed to creep, thermalfatigue and hot corrosion. Premature failure of blades in the combustion zone was reported in one of theaero-engines. The engine had both the compressor and the free-turbine in a common shaft. Detailedfailure analysis revealed the presence of creep voids in the blades that failed. Failure of turbine bladeswas also detected in another aero-engine operating in a coastal environment. In this failure, the protectivecoating on the blades was cracked at many locations. Grain boundary spikes were observed on these locations.The primary cause of this failure was the hot corrosion followed by creep damage

  2. Semigroup Method for a Mathematical Model in Reliability Analysis

    Geni Gupur; LI Xue-zhi


    The system which consists of a reliable machine, an unreliable machine and a storage buffer with infinite many workpieces has been studied. The existence of a unique positive time-dependent solution of the model corresponding to the system has been obtained by using C0-semigroup theory of linear operators in functional analysis.

  3. System Reliability Analysis Capability and Surrogate Model Application in RAVEN

    Rabiti, Cristian; Alfonsi, Andrea; Huang, Dongli; Gleicher, Frederick; Wang, Bei; Adbel-Khalik, Hany S.; Pascucci, Valerio; Smith, Curtis L.


    This report collect the effort performed to improve the reliability analysis capabilities of the RAVEN code and explore new opportunity in the usage of surrogate model by extending the current RAVEN capabilities to multi physics surrogate models and construction of surrogate models for high dimensionality fields.

  4. Test-retest reliability of trunk accelerometric gait analysis

    Henriksen, Marius; Lund, Hans; Moe-Nilssen, R


    The purpose of this study was to determine the test-retest reliability of a trunk accelerometric gait analysis in healthy subjects. Accelerations were measured during walking using a triaxial accelerometer mounted on the lumbar spine of the subjects. Six men and 14 women (mean age 35.2; range 18...

  5. Interactive Reliability-Based Optimization of Structural Systems

    Pedersen, Claus

    In order to introduce the basic concepts within the field of reliability-based structural optimization problems, this chapter is devoted to a brief outline of the basic theories. Therefore, this chapter is of a more formal nature and used as a basis for the remaining parts of the thesis. In secti...

  6. Reliability-Based Shape Optimization using Stochastic Finite Element Methods

    Enevoldsen, Ib; Sørensen, John Dalsgaard; Sigurdsson, G.


    Application of first-order reliability methods FORM (see Madsen, Krenk & Lind [8)) in structural design problems has attracted growing interest in recent years, see e.g. Frangopol [4), Murotsu, Kishi, Okada, Yonezawa & Taguchi [9) and Sørensen [14). In probabilistically based optimal design...

  7. Study of the Service Reliability of Machines Based on Safety


    From the point of safety being the basic requirement of machine operation, equivalent failure number, which is employed to replace the actual statistical failure number, is introduced. Calculating theory of service reliability indexes of machines based on safety is developed. The method proposed in this paper can reflect the damage degree of failure.

  8. Reliability-Based Inspection Planning for Structural Systems

    Sørensen, John Dalsgaard


    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 wi...

  9. Reliability Based Optimum Design of a Gear Box



    Full Text Available The gear box represents an important mechanical sub system. In machine tools, the propose of a gear box is to provide a series of useful output speeds so that the machining operation can be carried out at its most optimum operating conditions high spindle speeds with low feed rate for roughing operations. An important aspect in the design of machine tool transmission is to keep the cost and volume of the gear box to a minimum. The probabilistic approach to design has been considered to be more rational compared to the conventional design approach based on the factor of safety. The existence of uncertainties in either engineering simulations or manufacturing processes calls for a reliability-based design optimization (RBDO model for robust and cost-effective designs. In the present work a three shaft four speed gear box is designed using reliability principles. For the specified reliability of the system (Gear box, component reliability (Gear pair is calculated by considering the system as a series system. Design is considered to be safe and adequate if the probability of failure of gear box is less than or equal to a specified quantity in each of the two failure modes. A FORTRAN program has been developed to calculate the mean values of face widths of gears for the minimum mass of gear box. By changing the probability of failure of system variations in the face widths are studied. The reliability based optimum design results are compared with those obtained by deterministic optimum design. The minimum mass of the gear box is increase as the specified values of the reliability is increased.

  10. Human Reliability Analysis for Digital Human-Machine Interfaces

    Ronald L. Boring


    This paper addresses the fact that existing human reliability analysis (HRA) methods do not provide guidance on digital human-machine interfaces (HMIs). Digital HMIs are becoming ubiquitous in nuclear power operations, whether through control room modernization or new-build control rooms. Legacy analog technologies like instrumentation and control (I&C) systems are costly to support, and vendors no longer develop or support analog technology, which is considered technologically obsolete. Yet, despite the inevitability of digital HMI, no current HRA method provides guidance on how to treat human reliability considerations for digital technologies.

  11. Modelling application for cognitive reliability and error analysis method

    Fabio De Felice


    Full Text Available The automation of production systems has delegated to machines the execution of highly repetitive and standardized tasks. In the last decade, however, the failure of the automatic factory model has led to partially automated configurations of production systems. Therefore, in this scenario, centrality and responsibility of the role entrusted to the human operators are exalted because it requires problem solving and decision making ability. Thus, human operator is the core of a cognitive process that leads to decisions, influencing the safety of the whole system in function of their reliability. The aim of this paper is to propose a modelling application for cognitive reliability and error analysis method.

  12. Congestion Control Based on Reliable Transmission in Wireless Sensor Networks

    Hua Sun


    Full Text Available A new congestion control method is proposed in this paper. It makes use of the combination of buffer queue length and its variation rate to estimate the degree of congestion. It divides the node states and adopts various bandwidth allocation strategies according to different states, which ensures the reliable transmission of emergent information. Firstly, this paper introduces the queue model with priorities, divides the services according to different data flows and makes a detailed introduction on congestion adjustment mechanism based on the above information. The simulation experiment shows that the congestion control mechanism in this paper can ensure the reliable transmission of emergency information in monitoring sensor networks

  13. Accident Sequence Evaluation Program: Human reliability analysis procedure

    Swain, A.D.


    This document presents a shortened version of the procedure, models, and data for human reliability analysis (HRA) which are presented in the Handbook of Human Reliability Analysis With emphasis on Nuclear Power Plant Applications (NUREG/CR-1278, August 1983). This shortened version was prepared and tried out as part of the Accident Sequence Evaluation Program (ASEP) funded by the US Nuclear Regulatory Commission and managed by Sandia National Laboratories. The intent of this new HRA procedure, called the ''ASEP HRA Procedure,'' is to enable systems analysts, with minimal support from experts in human reliability analysis, to make estimates of human error probabilities and other human performance characteristics which are sufficiently accurate for many probabilistic risk assessments. The ASEP HRA Procedure consists of a Pre-Accident Screening HRA, a Pre-Accident Nominal HRA, a Post-Accident Screening HRA, and a Post-Accident Nominal HRA. The procedure in this document includes changes made after tryout and evaluation of the procedure in four nuclear power plants by four different systems analysts and related personnel, including human reliability specialists. The changes consist of some additional explanatory material (including examples), and more detailed definitions of some of the terms. 42 refs.

  14. Generating function approach to reliability analysis of structural systems


    The generating function approach is an important tool for performance assessment in multi-state systems. Aiming at strength reliability analysis of structural systems, generating function approach is introduced and developed. Static reliability models of statically determinate, indeterminate systems and fatigue reliability models are built by constructing special generating functions, which are used to describe probability distributions of strength (resistance), stress (load) and fatigue life, by defining composite operators of generating functions and performance structure functions thereof. When composition operators are executed, computational costs can be reduced by a big margin by means of collecting like terms. The results of theoretical analysis and numerical simulation show that the generating function approach can be widely used for probability modeling of large complex systems with hierarchical structures due to the unified form, compact expression, computer program realizability and high universality. Because the new method considers twin loads giving rise to component failure dependency, it can provide a theoretical reference and act as a powerful tool for static, dynamic reliability analysis in civil engineering structures and mechanical equipment systems with multi-mode damage coupling.

  15. Identifying Sources of Difference in Reliability in Content Analysis

    Elizabeth Murphy


    Full Text Available This paper reports on a case study which identifies and illustrates sources of difference in agreement in relation to reliability in a context of quantitative content analysis of a transcript of an online asynchronous discussion (OAD. Transcripts of 10 students in a month-long online asynchronous discussion were coded by two coders using an instrument with two categories, five processes, and 19 indicators of Problem Formulation and Resolution (PFR. Sources of difference were identified in relation to: coders; tasks; and students. Reliability values were calculated at the levels of categories, processes, and indicators. At the most detailed level of coding on the basis of the indicator, findings revealed that the overall level of reliability between coders was .591 when measured with Cohen’s kappa. The difference between tasks at the same level ranged from .349 to .664, and the difference between participants ranged from .390 to .907. Implications for training and research are discussed.

  16. Modeling and Analysis of Component Faults and Reliability

    Le Guilly, Thibaut; Olsen, Petur; Ravn, Anders Peter;


    that are automatically generated. The stochastic information on the faults is used to estimate the reliability of the fault affected system. The reliability is given with respect to properties of the system state space. We illustrate the process on a concrete example using the Uppaal model checker for validating...... the ideal system model and the fault modeling. Then the statistical version of the tool, UppaalSMC, is used to find reliability estimates.......This chapter presents a process to design and validate models of reactive systems in the form of communicating timed automata. The models are extended with faults associated with probabilities of occurrence. This enables a fault tree analysis of the system using minimal cut sets...

  17. Reliability analysis of two unit parallel repairable industrial system

    Mohit Kumar Kakkar


    Full Text Available The aim of this work is to present a reliability and profit analysis of a two-dissimilar parallel unit system under the assumption that operative unit cannot fail after post repair inspection and replacement and there is only one repair facility. Failure and repair times of each unit are assumed to be uncorrelated. Using regenerative point technique various reliability characteristics are obtained which are useful to system designers and industrial managers. Graphical behaviors of mean time to system failure (MTSF and profit function have also been studied. In this paper, some important measures of reliability characteristics of a two non-identical unit standby system model with repair, inspection and post repair are obtained using regenerative point technique.

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



    Full Text Available 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, etc. 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

  19. Integrated Reliability-Based Optimal Design of Structures

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle


    the reliability decreases with time it is often necessary to design an inspection and repair programme. For example the reliability of offshore steel structures decreases with time due to corrosion and development of fatigue cracks. Until now most inspection and repair strategies are based on experience rather......In conventional optimal design of structural systems the weight or the initial cost of the structure is usually used as objective function. Further, the constraints require that the stresses and/or strains at some critical points have to be less than some given values. Finally, all variables...... and parameters are assumed to be deterministic quantities. In this paper a probabilistic formulation is used. Some of the quantities specifying the load and the strength of the structure are modelled as random variables, and the constraints specify that the reliability of the structure has to exceed some given...

  20. NHPP-Based Software Reliability Models Using Equilibrium Distribution

    Xiao, Xiao; Okamura, Hiroyuki; Dohi, Tadashi

    Non-homogeneous Poisson processes (NHPPs) have gained much popularity in actual software testing phases to estimate the software reliability, the number of remaining faults in software and the software release timing. In this paper, we propose a new modeling approach for the NHPP-based software reliability models (SRMs) to describe the stochastic behavior of software fault-detection processes. The fundamental idea is to apply the equilibrium distribution to the fault-detection time distribution in NHPP-based modeling. We also develop efficient parameter estimation procedures for the proposed NHPP-based SRMs. Through numerical experiments, it can be concluded that the proposed NHPP-based SRMs outperform the existing ones in many data sets from the perspective of goodness-of-fit and prediction performance.

  1. Analysis of the Reliability of the "Alternator- Alternator Belt" System

    Ivan Mavrin


    Full Text Available Before starting and also during the exploitation of va1ioussystems, it is vety imp011ant to know how the system and itsparts will behave during operation regarding breakdowns, i.e.failures. It is possible to predict the service behaviour of a systemby determining the functions of reliability, as well as frequencyand intensity of failures.The paper considers the theoretical basics of the functionsof reliability, frequency and intensity of failures for the twomain approaches. One includes 6 equal intetvals and the other13 unequal intetvals for the concrete case taken from practice.The reliability of the "alternator- alternator belt" system installedin the buses, has been analysed, according to the empiricaldata on failures.The empitical data on failures provide empirical functionsof reliability and frequency and intensity of failures, that arepresented in tables and graphically. The first analysis perfO!med by dividing the mean time between failures into 6 equaltime intervals has given the forms of empirical functions of fa ilurefrequency and intensity that approximately cotTespond totypical functions. By dividing the failure phase into 13 unequalintetvals with two failures in each interval, these functions indicateexplicit transitions from early failure inte1val into the randomfailure interval, i.e. into the ageing intetval. Functions thusobtained are more accurate and represent a better solution forthe given case.In order to estimate reliability of these systems with greateraccuracy, a greater number of failures needs to be analysed.

  2. Reliability of MR-Based Volumetric 3-D Analysis of Pelvic Muscles among Subjects with Low Back with Leg Pain and Healthy Volunteers.

    Elżbieta Skorupska

    Full Text Available Lately, the diagnostic value of magnetic resonance imaging, Lasègue sign and classic neurological signs have been considered not accurate enough to distinguish the radicular from non-radicular low back with leg pain (LBLP and a calculation of the symptomatic side muscle volume has been indicated as a probable valuable marker. However, only the multifidus muscle volume has been calculated so far. The main objective of the study was to verify whether LBLP subjects presented symptomatic side pelvic muscle atrophy compared to healthy volunteers. The second aim was to assess the inter-rater reliability of 3-D manual method for segmenting and measuring the volume of the gluteus maximus, gluteus medius, gluteus minimus and piriformis muscles in both LBLP patients and healthy subjects.Two independent raters analyzed MR images of LBLP and healthy subjects towards muscle volume of four pelvic muscles, i.e. the piriformis, gluteus minimus, gluteus medius and gluteus maximus. For both sides, the MR images of the muscles without adipose tissue infiltration were manually segmented in 3-D medical images.Symptomatic muscle atrophy was confirmed in only over 50% of LBLP subjects (gluteus maximus (p<0.001, gluteus minimus (p<0.01 and piriformis (p<0.05. The ICC values indicated that the inter-rater reproducibility was greater than 0.90 for all measurements (LBLP and healthy subjects, except for the measurement of the right gluteus medius muscle in LBLP patients, which was equal to 0.848.More than 50% of LBLP subjects presented symptomatic gluteus maximus, gluteus minimus and piriformis muscle atrophy. 3-D manual segmentation reliably measured muscle volume in all the measured pelvic muscles in both healthy and LBLP subjects. To answer the question of what kind of muscle atrophy is indicative of radicular or non-radicular pain further studies are required.

  3. Reliability-based design optimization of composite stiffened panels in post-buckling regime

    Lopez, C.; Bacarreza Nogales, OR; Baldomir, A.; Hernandez, S; Aliabadi, MH


    This paper focuses on Deterministic and Reliability Based Design Optimization (DO and RBDO) of composite stiffened panels considering post-buckling regime and progressive failure analysis. The ultimate load that a post-buckled panel can hold is to be maximised by changing the stacking sequence of both skin and stringers composite layups. The RBDO problem looks for a design that collapses beyond the shortening of failure obtained in the DO phase with a target reliability while considering unce...

  4. Reliability analysis of a wastewater treatment plant using fault tree analysis and Monte Carlo simulation.

    Taheriyoun, Masoud; Moradinejad, Saber


    The reliability of a wastewater treatment plant is a critical issue when the effluent is reused or discharged to water resources. Main factors affecting the performance of the wastewater treatment plant are the variation of the influent, inherent variability in the treatment processes, deficiencies in design, mechanical equipment, and operational failures. Thus, meeting the established reuse/discharge criteria requires assessment of plant reliability. Among many techniques developed in system reliability analysis, fault tree analysis (FTA) is one of the popular and efficient methods. FTA is a top down, deductive failure analysis in which an undesired state of a system is analyzed. In this study, the problem of reliability was studied on Tehran West Town wastewater treatment plant. This plant is a conventional activated sludge process, and the effluent is reused in landscape irrigation. The fault tree diagram was established with the violation of allowable effluent BOD as the top event in the diagram, and the deficiencies of the system were identified based on the developed model. Some basic events are operator's mistake, physical damage, and design problems. The analytical method is minimal cut sets (based on numerical probability) and Monte Carlo simulation. Basic event probabilities were calculated according to available data and experts' opinions. The results showed that human factors, especially human error had a great effect on top event occurrence. The mechanical, climate, and sewer system factors were in subsequent tier. Literature shows applying FTA has been seldom used in the past wastewater treatment plant (WWTP) risk analysis studies. Thus, the developed FTA model in this study considerably improves the insight into causal failure analysis of a WWTP. It provides an efficient tool for WWTP operators and decision makers to achieve the standard limits in wastewater reuse and discharge to the environment.

  5. Reliability-based generation resource planning in electricity markets

    Moghaddam, Maziar Mirhosseini; Javidi, Mohammad Hossein


    This paper proposes a reliability-based competitive generation resource planning model in electricity markets. The Monte Carlo simulation method is applied to consider random outages of generation units and transmission lines as well as load uncertainty. In order to determine the optimal plan for installation of candidate generating units, the decisions of generation companies (GenCos) and the independent system operators (ISOs) are investigated. The method is based on an iterative pro...

  6. Reliability-Based Optimal Design for Very Large Floating Structure

    ZHANG Shu-hua(张淑华); FUJIKUBO Masahiko


    Costs and losses induced by possible future extreme environmental conditions and difficulties in repairing post-yielding damage strongly suggest the need for proper consideration in design rather than just life loss prevention. This can be addressed through the development of design methodology that balances the initial cost of the very large floating structure (VLFS) against the expected potential losses resulting from future extreme wave-induced structural damage. Here, the development of a methodology for determining optimal, cost-effective design will be presented and applied to a VLFS located in the Tokyo bay. Optimal design criteria are determined based on the total expected life-cycle cost and acceptable damage probability and curvature of the structure, and a set of sizes of the structure are obtained. The methodology and applications require expressions of the initial cost and the expected life-cycle damage cost as functions of the optimal design variables. This study includes the methodology, total life-cycle cost function, structural damage modeling, and reliability analysis.

  7. Reliability analysis of the control system of large-scale vertical mixing equipment


    The control system of vertical mixing equipment is a concentrate distributed monitoring system (CDMS).A reliability analysis model was built and its analysis was conducted based on reliability modeling theories such as the graph theory,Markov process,and redundancy theory.Analysis and operational results show that the control system can meet all technical requirements for high energy composite solid propellant manufacturing.The reliability performance of the control system can be considerably improved by adopting a control strategy combined with the hot spared redundancy of the primary system and the cold spared redundancy of the emergent one.The reliability performance of the control system can be also improved by adopting the redundancy strategy or improving the quality of each component and cable of the system.

  8. Topology Reliability Design and Optimization Analysis of IoT-Based Monitoring%物联网监测拓扑可靠性设计与优化分析

    田立勤; 林闯; 张琪; 陈振国


    unstable information transmission environment, this paper presents an effective mechanism and quantitative analysis method to guarantee the reliability of monitored region and remote backbone topology. This method highlights a dynamic optimization strategy to the topological reliability of those key transmission nodes. Theoretical analysis and simulation results show that this method is placed on traits such as even data fusion, effective energy saving and extensibility and is remarkable in improving the reliability of IoT-based remote monitoring. At the same time, theories from this paper have important theoretical and actual application reference value in guaranteeing topological reliability of IoT-based remote real-time monitoring of large region, such as agriculture, animal husbandry and forestry related industries.

  9. Cost-benefit Analysis Model for Distribution Automation System Reliability Based on Cloud Theory%基于云理论的配电自动化系统可靠性成本效益分析模型

    苏浩益; 贺伟明; 吴小勇; 谢振宁; 黄升; 罗杰


    On the basis of stating basic principles and characteristics of distribution automation system based on cable fault in-dicator,cost-benefit analysis model for distribution automation system reliability was proposed. By analyzing characteristics of distribution network in our country and combining engineering calculation method for distribution system reliability, quantitative calculation on cost and benefit of distribution automation system composed of cable fault indicator for improving system reliability was conducted. Combining cloud theory,economic evaluation on transform of distribution automation sys-tem was proceeded in order to find an entry point for ideal investment on distribution automation system. Example analysis indicated that this model was provided with better practicability and feasibility.%在阐述基于电缆故障指示器的配电自动化系统的基本原理和特点的基础上,提出配电自动化系统可靠性成本效益分析模型。通过分析我国配电网的特点,结合配电系统可靠性的工程计算方法,对通过电缆故障指示器构成的配电自动化系统在提高系统可靠性方面的成本和效益进行定量计算。结合云理论对配电自动化系统改造进行经济评估,找到实施配电自动化系统理想投资的切入点。算例分析表明该模型具有较好的实用性和可行性。

  10. Semantic Web for Reliable Citation Analysis in Scholarly Publishing

    Ruben Tous


    Full Text Available Analysis of the impact of scholarly artifacts is constrained by current unreliable practices in cross-referencing, citation discovering, and citation indexing and analysis, which have not kept pace with the technological advances that are occurring in several areas like knowledge management and security. Because citation analysis has become the primary component in scholarly impact factor calculation, and considering the relevance of this metric within both the scholarly publishing value chain and (especially important the professional curriculum evaluation of scholarly professionals, we defend that current practices need to be revised. This paper describes a reference architecture that aims to provide openness and reliability to the citation-tracking lifecycle. The solution relies on the use of digitally signed semantic metadata in the different stages of the scholarly publishing workflow in such a manner that authors, publishers, repositories, and citation-analysis systems will have access to independent reliable evidences that are resistant to forgery, impersonation, and repudiation. As far as we know, this is the first paper to combine Semantic Web technologies and public-key cryptography to achieve reliable citation analysis in scholarly publishing

  11. Reliability Analysis of Random Vibration Transmission Path Systems

    Wei Zhao


    Full Text Available The vibration transmission path systems are generally composed of the vibration source, the vibration transfer path, and the vibration receiving structure. The transfer path is the medium of the vibration transmission. Moreover, the randomness of transfer path influences the transfer reliability greatly. In this paper, based on the matrix calculus, the generalized second moment technique, and the stochastic finite element theory, the effective approach for the transfer reliability of vibration transfer path systems was provided. The transfer reliability of vibration transfer path system with uncertain path parameters including path mass and path stiffness was analyzed theoretically and computed numerically, and the correlated mathematical expressions were derived. Thus, it provides the theoretical foundation for the dynamic design of vibration systems in practical project, so that most random path parameters can be considered to solve the random problems for vibration transfer path systems, which can avoid the system resonance failure.

  12. Design Optimization Method for Composite Components Based on Moment Reliability-Sensitivity Criteria

    Sun, Zhigang; Wang, Changxi; Niu, Xuming; Song, Yingdong


    In this paper, a Reliability-Sensitivity Based Design Optimization (RSBDO) methodology for the design of the ceramic matrix composites (CMCs) components has been proposed. A practical and efficient method for reliability analysis and sensitivity analysis of complex components with arbitrary distribution parameters are investigated by using the perturbation method, the respond surface method, the Edgeworth series and the sensitivity analysis approach. The RSBDO methodology is then established by incorporating sensitivity calculation model into RBDO methodology. Finally, the proposed RSBDO methodology is applied to the design of the CMCs components. By comparing with Monte Carlo simulation, the numerical results demonstrate that the proposed methodology provides an accurate, convergent and computationally efficient method for reliability-analysis based finite element modeling engineering practice.

  13. Reliability Assessment and Reliability-Based Inspection and Maintenance of Offshore Wind Turbines

    Ramirez, José Rangel

    actions are the most relevant and effective means of control of deterioration. The risk-based inspection planning methodology, based on Bayesian decision theory, represents an important tool to identify the suitable strategy to inspect and control the deterioration in structures such as offshore wind...... performance during the life cycle. The deterioration processes, such as fatigue and corrosion, are typically affecting offshore structural systems. This damage decreases the system performance and increases the risk of failure, thus not fulfilling the established safety criteria. Inspection and maintenance...... to their offshore location, no pollution risks and low human risks since they are unmanned. This allows the allocation of lower reliability level compared to e.g. oil & gas installations. With the incursion to water depths between 20 and 50 meters, the use of jacket and tripod structures represents a feasible...

  14. Reliable Classification of Geologic Surfaces Using Texture Analysis

    Foil, G.; Howarth, D.; Abbey, W. J.; Bekker, D. L.; Castano, R.; Thompson, D. R.; Wagstaff, K.


    Communication delays and bandwidth constraints are major obstacles for remote exploration spacecraft. Due to such restrictions, spacecraft could make use of onboard science data analysis to maximize scientific gain, through capabilities such as the generation of bandwidth-efficient representative maps of scenes, autonomous instrument targeting to exploit targets of opportunity between communications, and downlink prioritization to ensure fast delivery of tactically-important data. Of particular importance to remote exploration is the precision of such methods and their ability to reliably reproduce consistent results in novel environments. Spacecraft resources are highly oversubscribed, so any onboard data analysis must provide a high degree of confidence in its assessment. The TextureCam project is constructing a "smart camera" that can analyze surface images to autonomously identify scientifically interesting targets and direct narrow field-of-view instruments. The TextureCam instrument incorporates onboard scene interpretation and mapping to assist these autonomous science activities. Computer vision algorithms map scenes such as those encountered during rover traverses. The approach, based on a machine learning strategy, trains a statistical model to recognize different geologic surface types and then classifies every pixel in a new scene according to these categories. We describe three methods for increasing the precision of the TextureCam instrument. The first uses ancillary data to segment challenging scenes into smaller regions having homogeneous properties. These subproblems are individually easier to solve, preventing uncertainty in one region from contaminating those that can be confidently classified. The second involves a Bayesian approach that maximizes the likelihood of correct classifications by abstaining from ambiguous ones. We evaluate these two techniques on a set of images acquired during field expeditions in the Mojave Desert. Finally, the

  15. Connectivity-Based Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs

    Woo-Yong Choi


    Full Text Available We propose the efficient reliable multicast MAC protocol based on the connectivity information among the recipients. Enhancing the BMMM (Batch Mode Multicast MAC protocol, the reliable multicast MAC protocol significantly reduces the RAK (Request for ACK frame transmissions in a reasonable computational time and enhances the MAC performance. By the analytical performance analysis, the throughputs of the BMMM protocol and our proposed MAC protocol are derived. Numerical examples show that our proposed MAC protocol increases the reliable multicast MAC performance for IEEE 802.11 wireless LANs.

  16. Reliability test and failure analysis of high power LED packages*

    Chen Zhaohui; Zhang Qin; Wang Kai; Luo Xiaobing; Liu Sheng


    A new type application specific light emitting diode (LED) package (ASLP) with freeform polycarbonate lens for street lighting is developed, whose manufacturing processes are compatible with a typical LED packaging process. The reliability test methods and failure criterions from different vendors are reviewed and compared. It is found that test methods and failure criterions are quite different. The rapid reliability assessment standards are urgently needed for the LED industry. 85 ℃/85 RH with 700 mA is used to test our LED modules with three other vendors for 1000 h, showing no visible degradation in optical performance for our modules, with two other vendors showing significant degradation. Some failure analysis methods such as C-SAM, Nano X-ray CT and optical microscope are used for LED packages. Some failure mechanisms such as delaminations and cracks are detected in the LED packages after the accelerated reliability testing. The finite element simulation method is helpful for the failure analysis and design of the reliability of the LED packaging. One example is used to show one currently used module in industry is vulnerable and may not easily pass the harsh thermal cycle testing.

  17. Advanced response surface method for mechanical reliability analysis

    L(U) Zhen-zhou; ZHAO Jie; YUE Zhu-feng


    Based on the classical response surface method (RSM), a novel RSM using improved experimental points (EPs) is presented for reliability analysis. Two novel points are included in the presented method. One is the use of linear interpolation, from which the total EPs for determining the RS are selected to be closer to the actual failure surface;the other is the application of sequential linear interpolation to control the distance between the surrounding EPs and the center EP, by which the presented method can ensure that the RS fits the actual failure surface in the region of maximum likelihood as the center EPs converge to the actual most probable point (MPP). Since the fitting precision of the RS to the actual failure surface in the vicinity of the MPP, which has significant contribution to the probability of the failure surface being exceeded, is increased by the presented method, the precision of the failure probability calculated by RS is increased as well. Numerical examples illustrate the accuracy and efficiency of the presented method.

  18. Diagnostic reliability of MMPI-2 computer-based test interpretations.

    Pant, Hina; McCabe, Brian J; Deskovitz, Mark A; Weed, Nathan C; Williams, John E


    Reflecting the common use of the MMPI-2 to provide diagnostic considerations, computer-based test interpretations (CBTIs) also typically offer diagnostic suggestions. However, these diagnostic suggestions can sometimes be shown to vary widely across different CBTI programs even for identical MMPI-2 profiles. The present study evaluated the diagnostic reliability of 6 commercially available CBTIs using a 20-item Q-sort task developed for this study. Four raters each sorted diagnostic classifications based on these 6 CBTI reports for 20 MMPI-2 profiles. Two questions were addressed. First, do users of CBTIs understand the diagnostic information contained within the reports similarly? Overall, diagnostic sorts of the CBTIs showed moderate inter-interpreter diagnostic reliability (mean r = .56), with sorts for the 1/2/3 profile showing the highest inter-interpreter diagnostic reliability (mean r = .67). Second, do different CBTIs programs vary with respect to diagnostic suggestions? It was found that diagnostic sorts of the CBTIs had a mean inter-CBTI diagnostic reliability of r = .56, indicating moderate but not strong agreement across CBTIs in terms of diagnostic suggestions. The strongest inter-CBTI diagnostic agreement was found for sorts of the 1/2/3 profile CBTIs (mean r = .71). Limitations and future directions are discussed. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  19. Fault Diagnosis of Machine Based on Fuzzy Reliability Theory


    According to life analysis in reliability theory, certain diagnosis rules can be used to diagnose machines' faults. On this basis, considering the indefiniteness in machine working states, the accurate diagnosis rule was extended to fuzzy diagnosis rule by using basic concepts and methods of fuzzy mathematics. The formulas of fault probability under different conditions were deduced. In the end, an example is given and the results of two methods were compared.



    Recently, considerable emphasis has been laid to the reliability-based optimization model for water distribution systems. But considerable computational effort is needed to determine the reliability-based optimal design of large networks, even of mid-sized networks. In this paper, a new methodology is presented for the reliability analysis for water distribution systems. This methodology consists of two procedures. The first is that the optimal design is constrained only by the pressure heads at demand nodes, done in GRG2. Because the reliability constrains are removed from the optimal problem, a number of simulations do not need to be conducted, so the computer time is greatly decreased. Then, the second procedure is a linear optimal search procedure. In this linear procedure, the optimal results obtained by GRG2 are adjusted by the reliability constrains. The results are a group of commercial diameters of pipes and the constraints of pressure heads and reliability at nodes are satisfied. Therefore, the computer burden is significantly decreased, and the reliability-based optimization is of more practical use.

  1. 基于Kriging算法的隧道衬砌稳定可靠度分析%Reliability Analysis of Tunnel Lining Stability Based on Kriging Algorithm

    苏永华; 张鹏; 李翔


    According to the conventional theory of deformation pressure, the four-stage idea for evolution of deformation pressure of surrounding rock was proposed when adding the plasticity-separateness process to it. On this basis, the performance function for structural stability of tunnel lining was developed, and the fact that the reliability evaluation is hampered by the implicit form of performance function was indicated. By using the expression capability of variance function for the characteristics of random variables and the interpolation technique in Kriging algorithm as well as Latin hypercube sampling method, both the formulation of variance function for minimum support resistance of surrounding rock and the interpolation of performance function for tunnel lining stability were derived, and then the corresponding process for accomplishing abovementioned tasks was also presented,thus the problem of the calculation of reliability index in the context of the non-explicit expression of performance function for tunnel lining stability was resolved. In comparison with Monte-Carlo simulation method, the iterations of computation process in this illustrative example through the proposed procedure were alleviated to a large extent, the absolute error of failure probability is only 0.004 9% and the relative error is approximate to 2.523 8%, which demonstrates that the Kriging algorithm is not only efficient but also can fulfill the precision level of calculated results.%根据以往的变形压力理论增加了塑性-分离阶段,由此提出了围岩变形压力发展过程的4个阶段,并在上述理论基础上建立了隧道衬砌结构稳定的功能函数,指出了该功能函数的隐式特征在求解可靠度时的困难.利用Kriging算法中变异函数对随机变量特征的表达能力和Kriging算法的插值技术,结合拉丁超立方试验设计抽样方法,推导出了隧道围岩最小支护阻力的变异函数建立方法以及隧道衬砌结构稳

  2. Fatigue Reliability Analysis of a Mono-Tower Platform

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Brincker, Rune


    In this paper, a fatigue reliability analysis of a Mono-tower platform is presented. The failure mode, fatigue failure in the butt welds, is investigated with two different models. The one with the fatigue strength expressed through SN relations, the other with the fatigue strength expressed thro...... of the natural period, damping ratio, current, stress spectrum and parameters describing the fatigue strength. Further, soil damping is shown to be significant for the Mono-tower.......In this paper, a fatigue reliability analysis of a Mono-tower platform is presented. The failure mode, fatigue failure in the butt welds, is investigated with two different models. The one with the fatigue strength expressed through SN relations, the other with the fatigue strength expressed...

  3. Reliability analysis method applied in slope stability: slope prediction and forecast on stability analysis

    Wenjuan ZHANG; Li CHEN; Ning QU; Hai'an LIANG


    Landslide is one kind of geologic hazards that often happens all over the world. It brings huge losses to human life and property; therefore, it is very important to research it. This study focused in combination between single and regional landslide, traditional slope stability analysis method and reliability analysis method. Meanwhile, methods of prediction of slopes and reliability analysis were discussed.

  4. A Sensitivity Analysis on Component Reliability from Fatigue Life Computations


    AD-A247 430 MTL TR 92-5 AD A SENSITIVITY ANALYSIS ON COMPONENT RELIABILITY FROM FATIGUE LIFE COMPUTATIONS DONALD M. NEAL, WILLIAM T. MATTHEWS, MARK G...HAGI OR GHANI NUMBI:H(s) Donald M. Neal, William T. Matthews, Mark G. Vangel, and Trevor Rudalevige 9. PERFORMING ORGANIZATION NAME AND ADDRESS lU...Technical Information Center, Cameron Station, Building 5, 5010 Duke Street, Alexandria, VA 22304-6145 2 ATTN: DTIC-FDAC I MIAC/ CINDAS , Purdue




    A reliable validation based on the optical flow visualization for numerical simula-tions of complex flowfields is addressed in this paper. Several test cases, including two-dimensional,axisymmetric and three-dimensional flowfields, were presented to demonstrate the effectiveness of the validation and gain credibility of numerical solutions of complex flowfields. In the validation, imagesof these flowfields were constructed from numerical results based on the principle of the optical flowvisualization, and compared directly with experimental interferograms. Because both experimental and numerical results axe of identical physical representation, the agreement between them can be evaluatedeffectively by examining flow structures as well as checking discrepancies in density. The study shows that the reliable validation can be achieved by using the direct comparison between numerical and experiment results without any loss of accuracy in either of them.

  6. Development of seismic technology and reliability based on vibration tests

    Sasaki, Youichi [Nuclear Power Engineering Corp., Tokyo (Japan)


    This paper deals with some of the vibration tests and investigations on the seismic safety of nuclear power plants (NPPs) in Japan. To ensure the reliability of the seismic safety of nuclear power plants, nuclear power plants in Japan have been designed according to the Technical Guidelines for Aseismic Design of Nuclear Power Plants. This guideline has been developed based on technical date base and findings which were obtained from many vibration tests and investigations. Besides the tests for the guideline, proving tests on seismic reliability of operating nuclear power plants equipment and systems have been carried out. In this paper some vibration tests and their evaluation results are presented. They have crucially contributed to develop the guideline. (J.P.N.)

  7. Reliability Based Optimization of Composite Laminates for Frequency Constraint

    Wu Hao; Yan Ying; Liu Yujia


    The reliability based optimization (RBO) issue of composite laminates under fundamental frequency constraint is studied. Considering the uncertainties of material properties, the frequency constraint reliability of the structure is evaluated by the combination of response surface method (RSM) and finite element method. An optimization algorithm is developed based on the mechanism of laminate frequency characteristics, to optimize the laminate in terms of the ply amount and orientation angles. Numerical examples of composite laminates and cylindrical shell illustrate the advantages of the present optimization algorithm on the efficiency and applicability respects.The optimal solutions of RBO are obviously different from the deterministic optimization results, and the necessity of considering material property uncertainties in the composite srtuctural frequency constraint optimization is revealed.




    A reliable validation based on the optical flow visualization for numerical simulations of complex flowfields is addressed in this paper.Several test cases,including two-dimensional,axisymmetric and three-dimensional flowfields,were presented to demonstrate the effectiveness of the validation and gain credibility of numerical solutions of complex flowfields.In the validation,images of these flowfields were constructed from numerical results based on the principle of the optical flow visualization,and compared directly with experimental interferograms.Because both experimental and numerical results are of identical physical representation,the agreement between them can be evaluated effectively by examining flow structures as well as checking discrepancies in density.The study shows that the reliable validation can be achieved by using the direct comparison between numerical and experiment results without any loss of accuracy in either of them.

  9. Modeling Sensor Reliability in Fault Diagnosis Based on Evidence Theory.

    Yuan, Kaijuan; Xiao, Fuyuan; Fei, Liguo; Kang, Bingyi; Deng, Yong


    Sensor data fusion plays an important role in fault diagnosis. Dempster-Shafer (D-R) evidence theory is widely used in fault diagnosis, since it is efficient to combine evidence from different sensors. However, under the situation where the evidence highly conflicts, it may obtain a counterintuitive result. To address the issue, a new method is proposed in this paper. Not only the statistic sensor reliability, but also the dynamic sensor reliability are taken into consideration. The evidence distance function and the belief entropy are combined to obtain the dynamic reliability of each sensor report. A weighted averaging method is adopted to modify the conflict evidence by assigning different weights to evidence according to sensor reliability. The proposed method has better performance in conflict management and fault diagnosis due to the fact that the information volume of each sensor report is taken into consideration. An application in fault diagnosis based on sensor fusion is illustrated to show the efficiency of the proposed method. The results show that the proposed method improves the accuracy of fault diagnosis from 81.19% to 89.48% compared to the existing methods.

  10. Analysis and Reliability Performance Comparison of Different Facial Image Features

    J. Madhavan


    Full Text Available This study performs reliability analysis on the different facial features with weighted retrieval accuracy on increasing facial database images. There are many methods analyzed in the existing papers with constant facial databases mentioned in the literature review. There were not much work carried out to study the performance in terms of reliability and also how the method will perform on increasing the size of the database. In this study certain feature extraction methods were analyzed on the regular performance measure and also the performance measures are modified to fit the real time requirements by giving weight ages for the closer matches. In this study four facial feature extraction methods are performed, they are DWT with PCA, LWT with PCA, HMM with SVD and Gabor wavelet with HMM. Reliability of these methods are analyzed and reported. Among all these methods Gabor wavelet with HMM gives more reliability than other three methods performed. Experiments are carried out to evaluate the proposed approach on the Olivetti Research Laboratory (ORL face database.

  11. A Robust and Reliability-Based Optimization Framework for Conceptual Aircraft Wing Design

    Paiva, Ricardo Miguel

    A robustness and reliability based multidisciplinary analysis and optimization framework for aircraft design is presented. Robust design optimization and Reliability Based Design Optimization are merged into a unified formulation which streamlines the setup of optimization problems and aims at preventing foreseeable implementation issues in uncertainty based design. Surrogate models are evaluated to circumvent the intensive computations resulting from using direct evaluation in nondeterministic optimization. Three types of models are implemented in the framework: quadratic interpolation, regression Kriging and artificial neural networks. Regression Kriging presents the best compromise between performance and accuracy in deterministic wing design problems. The performance of the simultaneous implementation of robustness and reliability is evaluated using simple analytic problems and more complex wing design problems, revealing that performance benefits can still be achieved while satisfying probabilistic constraints rather than the simpler (and not as computationally intensive) robust constraints. The latter are proven to to be unable to follow a reliability constraint as uncertainty in the input variables increases. The computational effort of the reliability analysis is further reduced through the implementation of a coordinate change in the respective optimization sub-problem. The computational tool developed is a stand-alone application and it presents a user-friendly graphical user interface. The multidisciplinary analysis and design optimization tool includes modules for aerodynamics, structural, aeroelastic and cost analysis, that can be used either individually or coupled.

  12. Mechanical system reliability analysis using a combination of graph theory and Boolean function

    Tang, J


    A new method based on graph theory and Boolean function for assessing reliability of mechanical systems is proposed. The procedure for this approach consists of two parts. By using the graph theory, the formula for the reliability of a mechanical system that considers the interrelations of subsystems or components is generated. Use of the Boolean function to examine the failure interactions of two particular elements of the system, followed with demonstrations of how to incorporate such failure dependencies into the analysis of larger systems, a constructive algorithm for quantifying the genuine interconnections between the subsystems or components is provided. The combination of graph theory and Boolean function provides an effective way to evaluate the reliability of a large, complex mechanical system. A numerical example demonstrates that this method an effective approaches in system reliability analysis.

  13. Methodological Approach for Performing Human Reliability and Error Analysis in Railway Transportation System

    Fabio De Felice


    Full Text Available Today, billions of dollars are being spent annually world wide to develop, manufacture, and operate transportation system such trains, ships, aircraft, and motor vehicles. Around 70 to 90 percent oftransportation crashes are, directly or indirectly, the result of human error. In fact, with the development of technology, system reliability has increased dramatically during the past decades, while human reliability has remained unchanged over the same period. Accordingly, human error is now considered as the most significant source of accidents or incidents in safety-critical systems. The aim of the paper is the proposal of a methodological approach to improve the transportation system reliability and in particular railway transportation system. The methodology presented is based on Failure Modes, Effects and Criticality Analysis (FMECA and Human Reliability Analysis (HRA.

  14. Methods for reliability based design optimization of structural components

    Dersjö, Tomas


    Cost and quality are key properties of a product, possibly even the two most important. Onedefinition of quality is fitness for purpose. Load-bearing products, i.e. structural components,loose their fitness for purpose if they fail. Thus, the ability to withstand failure is a fundamentalmeasure of quality for structural components. Reliability based design optimization(RBDO) is an approach for development of structural components which aims to minimizethe cost while constraining the probabili...

  15. AMOVA ["Accumulative Manifold Validation Analysis"]: An Advanced Statistical Methodology Designed to Measure and Test the Validity, Reliability, and Overall Efficacy of Inquiry-Based Psychometric Instruments

    Osler, James Edward, II


    This monograph provides an epistemological rational for the Accumulative Manifold Validation Analysis [also referred by the acronym "AMOVA"] statistical methodology designed to test psychometric instruments. This form of inquiry is a form of mathematical optimization in the discipline of linear stochastic modelling. AMOVA is an in-depth…

  16. 基于Monte Carlo和Rosenblueth方法的边坡可靠性分析及其在工程实践中的应用%Reliability analysis of slopes based on the means of Monte Carlo and Rosenblueth



    Traditionally,the safety factor which is a certain value calculated by a certain method was often used as evaluation indexes of slope stability.But the variability of parameters was not took into account,so the safety factor could not express the degree of slope safety.For this reason,the concept of reliability was imported in this paper,and the Monte Carlo and Rosenblueth methods based on probability theory and mathematical statistics were used into slope reliability analysis,therefor the shortages of traditional evaluation methodology was offseted effectively.%传统上常以安全系数作为边坡稳定性的评价指标,但是安全系数只是由一种确定的方法计算所得的一个定值,没有考虑设计参数的变异性,因此安全系数很难表征边坡的安全程度,为此本文引入了可靠度的概念,并运用基于概率论和数理统计学的蒙特卡洛法(Monte Carlo)和Rosenblueth法进行边坡可靠性分析,有效的弥补了边坡传统评价方法的不足。

  17. Stochastic Differential Equation-Based Flexible Software Reliability Growth Model

    P. K. Kapur


    Full Text Available Several software reliability growth models (SRGMs have been developed by software developers in tracking and measuring the growth of reliability. As the size of software system is large and the number of faults detected during the testing phase becomes large, so the change of the number of faults that are detected and removed through each debugging becomes sufficiently small compared with the initial fault content at the beginning of the testing phase. In such a situation, we can model the software fault detection process as a stochastic process with continuous state space. In this paper, we propose a new software reliability growth model based on Itô type of stochastic differential equation. We consider an SDE-based generalized Erlang model with logistic error detection function. The model is estimated and validated on real-life data sets cited in literature to show its flexibility. The proposed model integrated with the concept of stochastic differential equation performs comparatively better than the existing NHPP-based models.

  18. Reliability-based design optimization with progressive surrogate models

    Kanakasabai, Pugazhendhi; Dhingra, Anoop K.


    Reliability-based design optimization (RBDO) has traditionally been solved as a nested (bilevel) optimization problem, which is a computationally expensive approach. Unilevel and decoupled approaches for solving the RBDO problem have also been suggested in the past to improve the computational efficiency. However, these approaches also require a large number of response evaluations during optimization. To alleviate the computational burden, surrogate models have been used for reliability evaluation. These approaches involve construction of surrogate models for the reliability computation at each point visited by the optimizer in the design variable space. In this article, a novel approach to solving the RBDO problem is proposed based on a progressive sensitivity surrogate model. The sensitivity surrogate models are built in the design variable space outside the optimization loop using the kriging method or the moving least squares (MLS) method based on sample points generated from low-discrepancy sampling (LDS) to estimate the most probable point of failure (MPP). During the iterative deterministic optimization, the MPP is estimated from the surrogate model for each design point visited by the optimizer. The surrogate sensitivity model is also progressively updated for each new iteration of deterministic optimization by adding new points and their responses. Four example problems are presented showing the relative merits of the kriging and MLS approaches and the overall accuracy and improved efficiency of the proposed approach.

  19. Strategy for Synthesis of Flexible Heat Exchanger Networks Embedded with System Reliability Analysis

    YI Dake; HAN Zhizhong; WANG Kefeng; YAO Pingjing


    System reliability can produce a strong influence on the performance of the heat exchanger network (HEN).In this paper,an optimization method with system reliability analysis for flexible HEN by genetic/simulated annealing algorithms (GA/SA) is presented.Initial flexible arrangements of HEN is received by pseudo-temperature enthalpy diagram.For determining system reliability of HEN,the connections of heat exchangers(HEXs) and independent subsystems in the HEN are analyzed by the connection sequence matrix(CSM),and the system reliability is measured by the independent subsystem including maximum number of HEXs in the HEN.As for the HEN that did not meet system reliability,HEN decoupling is applied and the independent subsystems in the HEN are changed by removing decoupling HEX,and thus the system reliability is elevated.After that,heat duty redistribution based on the relevant elements of the heat load loops and HEX areas are optimized in GA/SA.Then,the favorable network configuration,which matches both the most economical cost and system reliability criterion,is located.Moreover,particular features belonging to suitable decoupling HEX are extracted from calculations.Corresponding numerical example is presented to verify that the proposed strategy is effective to formulate optimal flexible HEN with system reliability measurement.

  20. 基于随机故障序列的制造系统动态可靠性仿真%Dynamic Reliability Simulation for Manufacturing System Based on Stochastic Failure Sequence Analysis

    苏春; 王胜友


    采用随机故障序列、Petri网理论和蒙特卡洛仿真评估制造系统的动态可靠性.给出随机故障序列、序列重要度以及关键部件的定义,阐述随机故障序列的分析流程.基于随机Petri网理论建立系统可靠性分析模型,得到系统状态标识表:由状态标识表构建可达树,根据可达树求得系统的随机故障序列集.利用最小路集方法判定系统故障与否,分析仿真过程中避免部件过度故障问题及其解决方法;利用蒙特卡洛仿真计算随机故障序列的发生规律,评估系统的动态可靠性.通过计算每一个故障序列发生的次数、频率和持续时间等指标,确定影响系统可靠性的关键部件和瓶颈环节,为系统可靠性增长提供了理论依据.完成某供油系统动态可靠性案例分析,仿真结果验证所提出方法的正确性和有效性.%System dynamic reliability for manufacturing system is investigated based on stochastic failure sequence(SFS) analysis, Petri nets theory and Monte Carlo simulation. The definitions of SFS, importance of sequence, and key components of system are given out. The analysis procedure for SFS is discussed. Analysis model for system reliability is established based on Petri nets theory, the state identification table of the system is built and the reachability tree is created, and all SFSs of the system can be obtained. System's failure states can be determined with the method of minimal path sets, and the method for avoiding components' excessive failure during simulation is also considered. Monte Carlo simulation is used to compute the occurrence of all the failure sequences and system dynamic reliability. By means of calculating the number of times, frequency, and time of duration of each failure sequence, we can get the key components and bottleneck parts which influence system reliability, it provides theoretical basis for system reliability growth. A case study for an oil supply system is




    RHIC has been successfully operated for 5 years as a collider for different species, ranging from heavy ions including gold and copper, to polarized protons. We present a critical analysis of reliability data for RHIC that not only identifies the principal factors limiting availability but also evaluates critical choices at design times and assess their impact on present machine performance. RHIC availability data are typical when compared to similar high-energy colliders. The critical analysis of operations data is the basis for studies and plans to improve RHIC machine availability beyond the 50-60% typical of high-energy colliders.

  2. Reliability-based design optimization via high order response surface method

    Li, Hong Shuang [Nanjing University of Aeronautics and Astronautics, Nanjing (China)


    To reduce the computational effort of reliability-based design optimization (RBDO), the response surface method (RSM) has been widely used to evaluate reliability constraints. We propose an efficient methodology for solving RBDO problems based on an improved high order response surface method (HORSM) that takes advantage of an efficient sampling method, Hermite polynomials and uncertainty contribution concept to construct a high order response surface function with cross terms for reliability analysis. The sampling method generates supporting points from Gauss-Hermite quadrature points, which can be used to approximate response surface function without cross terms, to identify the highest order of each random variable and to determine the significant variables connected with point estimate method. The cross terms between two significant random variables are added to the response surface function to improve the approximation accuracy. Integrating the nested strategy, the improved HORSM is explored in solving RBDO problems. Additionally, a sampling based reliability sensitivity analysis method is employed to reduce the computational effort further when design variables are distributional parameters of input random variables. The proposed methodology is applied on two test problems to validate its accuracy and efficiency. The proposed methodology is more efficient than first order reliability method based RBDO and Monte Carlo simulation based RBDO, and enables the use of RBDO as a practical design tool.

  3. Condition-based Human Reliability Assessment for digitalized control room

    Kang, H. G.; Jang, S. C.; Eom, H. S.; Ha, J. J


    In safety-critical systems, the generation failure of an actuation signal is caused by the concurrent failures of the automated systems and an operator action. These two sources of safety signals are complicatedly correlated. The failures of sensors or automated systems will cause a lack of necessary information for a human operator and result in error-forcing contexts such as the loss of corresponding alarms and indications. In the conventional analysis, the Human Error Probabilities (HEP) are estimated based on the assumption of 'normal condition of indications and alarms'. In order to construct a more realistic signal-generation failure model, we have to consider more complicated conditions in a more realistic manner. In this study, we performed two kinds of investigation for addressing this issue. We performed the analytic calculations for estimating the effect of sensors failures on the system unavailability and plant risk. For the single-parameter safety signals, the analysis result reveals that the quantification of the HEP should be performed by focusing on the 'no alarm from the automatic system and corresponding indications unavailable' situation. This study also proposes a Condition-Based Human Reliability Assessment (CBHRA) method in order to address these complicated conditions in a practical way. We apply the CBHRA method to the manual actuation of the safety features such as a reactor trip and auxiliary feedwater actuation in Korean Standard Nuclear Power Plants. In the case of conventional single HEP method, it is very hard to consider the multiple HE conditions. The merit of CBHRA is clearly shown in the application to the AFAS generation where no dominating HE condition exits. In this case, even if the HE conditions are carefully investigated, the single HEP method cannot accommodate the multiple conditions in a fault tree. On the other hand, the application result of the reactor trip in SLOCA shows that if there is a

  4. Mutation Analysis Approach to Develop Reliable Object-Oriented Software

    Monalisa Sarma


    Full Text Available In general, modern programs are large and complex and it is essential that they should be highly reliable in applications. In order to develop highly reliable software, Java programming language developer provides a rich set of exceptions and exception handling mechanisms. Exception handling mechanisms are intended to help developers build robust programs. Given a program with exception handling constructs, for an effective testing, we are to detect whether all possible exceptions are raised and caught or not. However, complex exception handling constructs make it tedious to trace which exceptions are handled and where and which exceptions are passed on. In this paper, we address this problem and propose a mutation analysis approach to develop reliable object-oriented programs. We have applied a number of mutation operators to create a large set of mutant programs with different type of faults. We then generate test cases and test data to uncover exception related faults. The test suite so obtained is applied to the mutant programs measuring the mutation score and hence verifying whether mutant programs are effective or not. We have tested our approach with a number of case studies to substantiate the efficacy of the proposed mutation analysis technique.

  5. Strength Reliability Analysis of Stiffened Cylindrical Shells Considering Failure Correlation

    Xu Bai; Liping Sun; Wei Qin; Yongkun Lv


    The stiffened cylindrical shell is commonly used for the pressure hull of submersibles and the legs of offshore platforms. There are various failure modes because of uncertainty with the structural size and material properties, uncertainty of the calculation model and machining errors. Correlations among failure modes must be considered with the structural reliability of stiffened cylindrical shells. However, the traditional method cannot consider the correlations effectively. The aim of this study is to present a method of reliability analysis for stiffened cylindrical shells which considers the correlations among failure modes. Firstly, the joint failure probability calculation formula of two related failure modes is derived through use of the 2D joint probability density function. Secondly, the full probability formula of the tandem structural system is given with consideration to the correlations among failure modes. At last, the accuracy of the system reliability calculation is verified through use of the Monte Carlo simulation. Result of the analysis shows the failure probability of stiffened cylindrical shells can be gained through adding the failure probability of each mode.

  6. Reliability Analysis of Penetration Systems Using Nondeterministic Methods



    Device penetration into media such as metal and soil is an application of some engineering interest. Often, these devices contain internal components and it is of paramount importance that all significant components survive the severe environment that accompanies the penetration event. In addition, the system must be robust to perturbations in its operating environment, some of which exhibit behavior which can only be quantified to within some level of uncertainty. In the analysis discussed herein, methods to address the reliability of internal components for a specific application system are discussed. The shock response spectrum (SRS) is utilized in conjunction with the Advanced Mean Value (AMV) and Response Surface methods to make probabilistic statements regarding the predicted reliability of internal components. Monte Carlo simulation methods are also explored.

  7. Issues in benchmarking human reliability analysis methods : a literature review.

    Lois, Erasmia (US Nuclear Regulatory Commission); Forester, John Alan; Tran, Tuan Q. (Idaho National Laboratory, Idaho Falls, ID); Hendrickson, Stacey M. Langfitt; Boring, Ronald L. (Idaho National Laboratory, Idaho Falls, ID)


    There is a diversity of human reliability analysis (HRA) methods available for use in assessing human performance within probabilistic risk assessment (PRA). Due to the significant differences in the methods, including the scope, approach, and underlying models, there is a need for an empirical comparison investigating the validity and reliability of the methods. To accomplish this empirical comparison, a benchmarking study is currently underway that compares HRA methods with each other and against operator performance in simulator studies. In order to account for as many effects as possible in the construction of this benchmarking study, a literature review was conducted, reviewing past benchmarking studies in the areas of psychology and risk assessment. A number of lessons learned through these studies are presented in order to aid in the design of future HRA benchmarking endeavors.

  8. Reliability-Based Structural Optimization of Wave Energy Converters

    Ambühl, Simon; Kramer, Morten; Sørensen, John Dalsgaard


    More and more wave energy converter (WEC) concepts are reaching prototype level. Once the prototype level is reached, the next step in order to further decrease the levelized cost of energy (LCOE) is optimizing the overall system with a focus on structural and maintenance (inspection) costs......, as well as on the harvested power from the waves. The target of a fully-developed WEC technology is not maximizing its power output, but minimizing the resulting LCOE. This paper presents a methodology to optimize the structural design of WECs based on a reliability-based optimization problem...

  9. Position Mooring Control Based on a Structural Reliability Criterion

    Fang, Shaoji; Leira, Bernt J.; Blanke, Mogens


    is achieved using structural reliability indices in a cost function, where both the mean mooring-line tension and dynamic effects are considered. An optimal set-point is automatically produced without need for manual interaction. The parameters of the extreme value distribution are calculated on-line thereby...... adapting the set-point calculations to the prevailing environment. In contrast to earlier approaches, several mooring line are simultaneously accounted for by the algorithm, not only the most critical one. Detailed simulations illustrate the features of the new method and it is shown that the structural...... reliability criterion based algorithm ensures the safety of mooring lines in a variety of external environmental conditions and also in situations of failure of a single line....

  10. Probabilistic confidence for decisions based on uncertain reliability estimates

    Reid, Stuart G.


    Reliability assessments are commonly carried out to provide a rational basis for risk-informed decisions concerning the design or maintenance of engineering systems and structures. However, calculated reliabilities and associated probabilities of failure often have significant uncertainties associated with the possible estimation errors relative to the 'true' failure probabilities. For uncertain probabilities of failure, a measure of 'probabilistic confidence' has been proposed to reflect the concern that uncertainty about the true probability of failure could result in a system or structure that is unsafe and could subsequently fail. The paper describes how the concept of probabilistic confidence can be applied to evaluate and appropriately limit the probabilities of failure attributable to particular uncertainties such as design errors that may critically affect the dependability of risk-acceptance decisions. This approach is illustrated with regard to the dependability of structural design processes based on prototype testing with uncertainties attributable to sampling variability.

  11. Reliability-Based Maintenance and Inspection Planning for Wind Turbines

    Sørensen, John Dalsgaard


    , local buckling of main tower, and failure of the foundation. This paper considers reliability-based optimal inspection and maintenance planning of wind turbines. Different formulations are considered of the objective function including benefits, building costs of the wind turbine, inspection...... and maintenance costs, and failure costs. Different reconstruction policies in case of failure are considered, including systematic reconstruction in case of failure, no reconstruction and failure of the control system. The concept of generic inspection and maintenance planning coupled with information from...... continuous monitoring is presented and illustrated. Illustrative examples for offshore wind turbines are presented, and as a part of the results optimal reliability levels for the different failure modes are obtained....

  12. Reliability-Based Control Design for Uncertain Systems

    Crespo, Luis G.; Kenny, Sean P.


    This paper presents a robust control design methodology for systems with probabilistic parametric uncertainty. Control design is carried out by solving a reliability-based multi-objective optimization problem where the probability of violating design requirements is minimized. Simultaneously, failure domains are optimally enlarged to enable global improvements in the closed-loop performance. To enable an efficient numerical implementation, a hybrid approach for estimating reliability metrics is developed. This approach, which integrates deterministic sampling and asymptotic approximations, greatly reduces the numerical burden associated with complex probabilistic computations without compromising the accuracy of the results. Examples using output-feedback and full-state feedback with state estimation are used to demonstrate the ideas proposed.

  13. Reliability-Based Topology Optimization Using Stochastic Response Surface Method with Sparse Grid Design

    Qinghai Zhao


    Full Text Available A mathematical framework is developed which integrates the reliability concept into topology optimization to solve reliability-based topology optimization (RBTO problems under uncertainty. Two typical methodologies have been presented and implemented, including the performance measure approach (PMA and the sequential optimization and reliability assessment (SORA. To enhance the computational efficiency of reliability analysis, stochastic response surface method (SRSM is applied to approximate the true limit state function with respect to the normalized random variables, combined with the reasonable design of experiments generated by sparse grid design, which was proven to be an effective and special discretization technique. The uncertainties such as material property and external loads are considered on three numerical examples: a cantilever beam, a loaded knee structure, and a heat conduction problem. Monte-Carlo simulations are also performed to verify the accuracy of the failure probabilities computed by the proposed approach. Based on the results, it is demonstrated that application of SRSM with SGD can produce an efficient reliability analysis in RBTO which enables a more reliable design than that obtained by DTO. It is also found that, under identical accuracy, SORA is superior to PMA in view of computational efficiency.

  14. Reliability analysis of foundation bearing capacity based on combined coefficients of variation%基于综合变异系数的地基承载力可靠性分析

    曹宇春; 刘富玲


    A simplified reliability and risk analysis method of foundation bearing capacity based on combined coefficients of variation of random variables is proposed using first order second moment technique. The laboratory results and historical published ones of coefficients of variation are taken into consideration as the combined coefficients of variation, which are adopted as the calculated coefficients of variation. The most likely values and their possible ranges of degrees of reliability, probabilities of failure and average expected losses can be obtained using suitable coefficients of variation besides the conventional deterministic analysis. This enables to make optimal design scheme and engineering decision. It has shown that the degrees of reliability of foundation bearing capacity are more sensitive to the internal friction angle compared with the unit weight and the cohesion. The width or area of foundation can be decided upon in terms of the required factor of safety, degree of reliability and probability of failure. Moreover, the combined coefficients of variation of random variables will gradually decrease with the weights increasing of coefficients of variation based on the in-situ investigation results;the corresponding degrees of reliability will increase and the probabilities of failure decrease due to that decrease of combined coefficients of variation.%采用一次二阶矩法,考虑岩土参量变异系数的试验及历史数据,提出了基于综合变异系数的地基承载力简化可靠性与风险分析方法。利用提出的简化可靠性与风险分析方法,可在传统确定性分析的基础上,采用合理的变异系数,分别得到与地基承载力有关的可靠度、破坏概率和平均期望损失的最可能值及其变化范围,为提出优化的地基基础设计方案和工程决策奠定基础;相对于土重度和黏聚力,地基承载力可靠度对于内摩擦角的变化更加敏感;设计时可以

  15. Preventive Replacement Decisions for Dragline Components Using Reliability Analysis

    Nuray Demirel


    Full Text Available Reliability-based maintenance policies allow qualitative and quantitative evaluation of system downtimes via revealing main causes of breakdowns and discussing required preventive activities against failures. Application of preventive maintenance is especially important for mining machineries since production is highly affected from machinery breakdowns. Overburden stripping operations are one of the integral parts in surface coal mine productions. Draglines are extensively utilized in overburden stripping operations and they achieve earthmoving activities with bucket capacities up to 168 m3. The massive structure and operational severity of these machines increase the importance of performance awareness for individual working components. Research on draglines is rarely observed in the literature and maintenance studies for these earthmovers have been generally ignored. On this basis, this paper offered a comprehensive reliability assessment for two draglines currently operating in the Tunçbilek coal mine and discussed preventive replacement for wear-out components of the draglines considering cost factors.

  16. Low Carbon-Oriented Optimal Reliability Design with Interval Product Failure Analysis and Grey Correlation Analysis

    Yixiong Feng


    Full Text Available The problem of large amounts of carbon emissions causes wide concern across the world, and it has become a serious threat to the sustainable development of the manufacturing industry. The intensive research into technologies and methodologies for green product design has significant theoretical meaning and practical value in reducing the emissions of the manufacturing industry. Therefore, a low carbon-oriented product reliability optimal design model is proposed in this paper: (1 The related expert evaluation information was prepared in interval numbers; (2 An improved product failure analysis considering the uncertain carbon emissions of the subsystem was performed to obtain the subsystem weight taking the carbon emissions into consideration. The interval grey correlation analysis was conducted to obtain the subsystem weight taking the uncertain correlations inside the product into consideration. Using the above two kinds of subsystem weights and different caution indicators of the decision maker, a series of product reliability design schemes is available; (3 The interval-valued intuitionistic fuzzy sets (IVIFSs were employed to select the optimal reliability and optimal design scheme based on three attributes, namely, low carbon, correlation and functions, and economic cost. The case study of a vertical CNC lathe proves the superiority and rationality of the proposed method.

  17. Multiobject Reliability Analysis of Turbine Blisk with Multidiscipline under Multiphysical Field Interaction

    Chun-Yi Zhang


    Full Text Available To study accurately the influence of the deformation, stress, and strain of turbine blisk on the performance of aeroengine, the comprehensive reliability analysis of turbine blisk with multiple disciplines and multiple objects was performed based on multiple response surface method (MRSM and fluid-thermal-solid coupling technique. Firstly, the basic thought of MRSM was introduced. And then the mathematical model of MRSM was established with quadratic polynomial. Finally, the multiple reliability analyses of deformation, stress, and strain of turbine blisk were completed under multiphysical field coupling by the MRSM, and the comprehensive performance of turbine blisk was evaluated. From the reliability analysis, it is demonstrated that the reliability degrees of the deformation, stress, and strain for turbine blisk are 0.9942, 0.9935, 0.9954, and 0.9919, respectively, when the allowable deformation, stress, and strain are 3.7 × 10−3 m, 1.07 × 109 Pa, and 1.12 × 10−2 m/m, respectively; besides, the comprehensive reliability degree of turbine blisk is 0.9919, which basically satisfies the engineering requirement of aeroengine. The efforts of this paper provide a promising approach method for multidiscipline multiobject reliability analysis.

  18. A general framework for a reliable multivariate analysis and pattern recognition in high-dimensional epidemiological data, based on cluster robustness: a tutorial to enrich the epidemiologists' toolkit.

    Lefèvre, T; Chauvin, P


    In an epidemiologist's toolbox, three main types of statistical tools can be found: means and proportions comparisons, linear or logistic regression models and Cox-type regression models. All these techniques have their own multivariate formulations, so that biases can be accounted for. Nonetheless, there is an entire set of natively massive multivariate techniques, which are based on weaker assumptions than classical statistical techniques are, and which seem to be underestimated or remain unknown to most epidemiologists. These techniques are used for pattern recognition or clustering – that is, for retrieving homogeneous groups in data without any a priori about these groups. They are widely used in connex domains such as genetics or biomolecular studies. Most clustering techniques require tuning specific parameters so that groups can be identified in data. A critical parameter to set is the number of groups the technique needs to discover. Different approaches to find the optimal number of groups are available, such as the silhouette approach and the robustness approach. This article presents the key aspects of clustering techniques (how proximity between observations is defined and how to find the number of groups), two archetypal techniques (namely the k-means and PAM algorithms) and how they relate to more classical statistical approaches. Through a theoretical, simple example and a real data application, we provide a complete framework within which classical epidemiological concerns can be reconsidered. We show how to (i) identify whether distinct groups exist in data, (ii) identify the optimal number of groups in data, (iii) label each observation according to its own group and (iv) analyze the groups identified according to separate and explicative data. In addition, how to achieve consistent results while removing sensitivity to initial conditions is explained. Clustering techniques, in conjunction with methods for parameter tuning, provide the

  19. Method for combination of actions based on stochastic processes in analysis of structural reliability%结构可靠度分析中作用的随机过程组合方法

    姚继涛; 解耀魁


    The analysis of structural reliability should be based on the probabilistic models describing directly the variety of actions and the method for combination of actions based on stochastic processes. However, the current method for combination of variable actions appearing with their frequent values or quasi-permanent values is actually the one based on random variables by maximum values expression, thus will lead to unreasonable results. According to stochastic model for variable action of equal time interval stationary binomial rectangular wave process, the interval samples corresponding to exceeded rates of frequent value and quasi-permanent value were determined, and the new concepts of frequent sequence values and quasi-permanent sequence values of variable actions were proposed. Consequently, the method for combination of actions based on stochastic process by sequence values expressions and models for reliability analysis were established. The proposed method is based on the theory of stochastic process, with clear and reasonable engineering concepts, thus can reflect accurately the ideas of actions combination, and derive reasonable results of reliability analysis, overcoming essentially the disadvantages of current method for combination of actions based on random variables.%结构可靠度分析应以直接描述作用随机变化的概率模型和随机过程组合方法为基础,但在目前的作用概率组合中,对由频遇值、准永久值参与组合的可变作用实际采用的是以最大值表达的随机变量组合方法,这将导致不合理的分析结果.依据可变作用的等时段平稳二项矩形波过程概率模型,确定与频遇值、准永久值超越比率对应的时段样本,提出可变作用频遇序位值和准永久序位值的概念,据此建立以作用序位值表达的随机过程组合方法和可靠度分析模型.该方法以随机过程理论为基础,具有明确、合理的工程概念,可准确反映作用组

  20. Reliability-Based Calibration of Partial Safety Factors for Wind Turbine Blades

    Toft, Henrik Stensgaard; Branner, Kim; Sørensen, John Dalsgaard


    The reliability of a wind turbine blade can be estimated using a response surface technique, the First Order Reliability Method (FORM) and Monte Carlo simulation. The response surface is here estimated based on nonlinear finite element analysis by which nonlinear failure modes due to e.g. buckling...... of the unidirectional laminas. For this failure mode the reliability is estimated along the centreline of the main spar cap. The results show significant variations in the reliability along the blade length....... can be taken into account. Stochastic models for the material properties and the load-effect are formulated in order to take physical, model and statistical uncertainties into account. The blade fails due to buckling of the main spar cap which results in high stresses in the transverse direction...

  1. Reliability-Based Calibration of Partial Safety Factors for Wind Turbine Blades

    Toft, Henrik Stensgaard; Branner, Kim; Sørensen, John Dalsgaard


    The reliability of a wind turbine blade can be estimated using a response surface technique, the First Order Reliability Method (FORM) and Monte Carlo simulation. The response surface is here estimated based on nonlinear finite element analysis by which nonlinear failure modes due to e.g. buckling...... can be taken into account. Stochastic models for the material properties and the load-effect are formulated in order to take physical, model and statistical uncertainties into account. The blade fails due to buckling of the main spar cap which results in high stresses in the transverse direction...... of the unidirectional laminas. For this failure mode the reliability is estimated along the centreline of the main spar cap. The results show significant variations in the reliability along the blade length....

  2. Reliability-Based Calibration of Partial Safety Factors for Wind Turbine Blades

    Toft, Henrik Stensgaard; Branner, Kim; Sørensen, John Dalsgaard;


    The reliability of a wind turbine blade can be estimated using a response surface technique, the First Order Reliability Method (FORM) and Monte Carlo simulation. The response surface is here estimated based on nonlinear finite element analysis by which nonlinear failure modes due to e.g. buckling...... of the unidirectional laminas. For this failure mode the reliability is estimated along the centreline of the main spar cap. The results show significant variations in the reliability along the blade length....... can be taken into account. Stochastic models for the material properties and the load-effect are formulated in order to take physical, model and statistical uncertainties into account. The blade fails due to buckling of the main spar cap which results in high stresses in the transverse direction...

  3. An Imprecise Probability Model for Structural Reliability Based on Evidence and Gray Theory

    Bin Suo


    Full Text Available To avoid the shortages and limitations of probabilistic and non-probabilistic reliability model for structural reliability analysis in the case of limited samples for basic variables, a new imprecise probability model is proposed. Confidence interval with a given confidence is calculated on the basis of small samples by gray theory, which is not depending on the distribution pattern of variable. Then basic probability assignments and focal elements are constructed and approximation methods of structural reliability based on belief and plausibility functions are proposed in the situation that structure limit state function is monotonic and non-monotonic, respectively. The numerical examples show that the new reliability model utilizes all the information included in small samples and considers both aleatory and epistemic uncertainties in them, thus it can rationally measure the safety of the structure and the measurement can be more and more accurate with the increasing of sample size.

  4. A Novel OBDD-Based Reliability Evaluation Algorithm for Wireless Sensor Networks on the Multicast Model

    Zongshuai Yan


    Full Text Available The two-terminal reliability calculation for wireless sensor networks (WSNs is a #P-hard problem. The reliability calculation of WSNs on the multicast model provides an even worse combinatorial explosion of node states with respect to the calculation of WSNs on the unicast model; many real WSNs require the multicast model to deliver information. This research first provides a formal definition for the WSN on the multicast model. Next, a symbolic OBDD_Multicast algorithm is proposed to evaluate the reliability of WSNs on the multicast model. Furthermore, our research on OBDD_Multicast construction avoids the problem of invalid expansion, which reduces the number of subnetworks by identifying the redundant paths of two adjacent nodes and s-t unconnected paths. Experiments show that the OBDD_Multicast both reduces the complexity of the WSN reliability analysis and has a lower running time than Xing’s OBDD- (ordered binary decision diagram- based algorithm.

  5. Reliability-based design optimization for nonlinear energy harvesters

    Seong, Sumin; Lee, Soobum; Hu, Chao


    The power output of a vibration energy harvesting device is highly sensitive to uncertainties in materials, manufacturing, and operating conditions. Although the use of a nonlinear spring (e.g., snap-through mechanism) in energy harvesting device has been reported to reduce the sensitivity of power output with respect to the excitation frequency, the nonlinear spring characteristic remains significantly sensitive and it causes unreliable power generation. In this paper, we present a reliability-based design optimization (RBDO) study of vibration energy harvesters. For a nonlinear harvester, a purely mechanical nonlinear spring design implemented in the middle of cantilever beam harvester is considered in the study. This design has the curved section in the center of beam that causes bi-stable configuration. When vibrating, the inertia of the tip mass activates the curved shell to cause snap-through buckling and make the nature of vibration nonlinear. In this paper, deterministic optimization (DO) is performed to obtain deterministic optimum of linear and nonlinear energy harvester configuration. As a result of the deterministic optimization, an optimum bi-stable vibration configuration of nonlinear harvester can be obtained for reliable power generation despite uncertainty on input vibration condition. For the linear harvester, RBDO is additionally performed to find the optimum design that satisfies a target reliability on power generation, while accounting for uncertainty in material properties and geometric parameters.


    Dustin Lawrence


    Full Text Available The purpose of this study was to inform decision makers at state and local levels, as well as property owners about the amount of water that can be supplied by rainwater harvesting systems in Texas so that it may be included in any future planning. Reliability of a rainwater tank is important because people want to know that a source of water can be depended on. Performance analyses were conducted on rainwater harvesting tanks for three Texas cities under different rainfall conditions and multiple scenarios to demonstrate the importance of optimizing rainwater tank design. Reliability curves were produced and reflect the percentage of days in a year that water can be supplied by a tank. Operational thresholds were reached in all scenarios and mark the point at which reliability increases by only 2% or less with an increase in tank size. A payback period analysis was conducted on tank sizes to estimate the amount of time it would take to recoup the cost of installing a rainwater harvesting system.

  7. A Bayesian Framework for Reliability Analysis of Spacecraft Deployments

    Evans, John W.; Gallo, Luis; Kaminsky, Mark


    Deployable subsystems are essential to mission success of most spacecraft. These subsystems enable critical functions including power, communications and thermal control. The loss of any of these functions will generally result in loss of the mission. These subsystems and their components often consist of unique designs and applications for which various standardized data sources are not applicable for estimating reliability and for assessing risks. In this study, a two stage sequential Bayesian framework for reliability estimation of spacecraft deployment was developed for this purpose. This process was then applied to the James Webb Space Telescope (JWST) Sunshield subsystem, a unique design intended for thermal control of the Optical Telescope Element. Initially, detailed studies of NASA deployment history, "heritage information", were conducted, extending over 45 years of spacecraft launches. This information was then coupled to a non-informative prior and a binomial likelihood function to create a posterior distribution for deployments of various subsystems uSing Monte Carlo Markov Chain sampling. Select distributions were then coupled to a subsequent analysis, using test data and anomaly occurrences on successive ground test deployments of scale model test articles of JWST hardware, to update the NASA heritage data. This allowed for a realistic prediction for the reliability of the complex Sunshield deployment, with credibility limits, within this two stage Bayesian framework.

  8. Asymptotic Sampling for Reliability Analysis of Adhesive Bonded Stepped Lap Composite Joints

    Kimiaeifar, Amin; Lund, Erik; Thomsen, Ole Thybo


    Reliability analysis coupled with finite element analysis (FEA) of composite structures is computationally very demanding and requires a large number of simulations to achieve an accurate prediction of the probability of failure with a small standard error. In this paper Asymptotic Sampling, which....... Three dimensional (3D) FEA is used for the structural analysis together with a design equation that is associated with a deterministic code-based design equation where reliability is secured by partial safety factors. The Tsai-Wu and the maximum principal stress failure criteria are used to predict...... failure in the composite and adhesive layers, respectively, and the results are compared with the target reliability level implicitly used in the wind turbine standard IEC 61400-1. The accuracy and efficiency of Asymptotic Sampling is investigated by comparing the results with predictions obtained using...

  9. Structure buckling and non-probabilistic reliability analysis of supercavitating vehicles

    AN Wei-guang; ZHOU Ling; AN Hai


    To perform structure buckling and reliability analysis on supercavitating vehicles with high velocity in the submarine, supercavitating vehicles were simplified as variable cross section beam firstly. Then structural buckling analysis of supercavitating vehicles with or without engine thrust was conducted, and the structural buckling safety margin equation of supercavitating vehicles was established. The indefinite information was de-scribed by interval set and the structure reliability analysis was performed by using non-probabilistic reliability method. Considering interval variables as random variables which satisfy uniform distribution, the Monte-Carlo method was used to calculate the non-probabilistic failure degree. Numerical examples of supercavitating vehi-cles were presented. Under different ratios of base diameter to cavitator diameter, the change tendency of non-probabilistic failure degree of structural buckling of supereavitating vehicles with or without engine thrust was studied along with the variety of speed.

  10. Reliability and Robustness Analysis of the Masinga Dam under Uncertainty

    Hayden Postle-Floyd


    Full Text Available Kenya’s water abstraction must meet the projected growth in municipal and irrigation demand by the end of 2030 in order to achieve the country’s industrial and economic development plan. The Masinga dam, on the Tana River, is the key to meeting this goal to satisfy the growing demands whilst also continuing to provide hydroelectric power generation. This study quantitatively assesses the reliability and robustness of the Masinga dam system under uncertain future supply and demand using probabilistic climate and population projections, and examines how long-term planning may improve the longevity of the dam. River flow and demand projections are used alongside each other as inputs to the dam system simulation model linked to an optimisation engine to maximise water availability. Water availability after demand satisfaction is assessed for future years, and the projected reliability of the system is calculated for selected years. The analysis shows that maximising power generation on a short-term year-by-year basis achieves 80%, 50% and 1% reliability by 2020, 2025 and 2030 onwards, respectively. Longer term optimal planning, however, has increased system reliability to up to 95% in 2020, 80% in 2025, and more than 40% in 2030 onwards. In addition, increasing the capacity of the reservoir by around 25% can significantly improve the robustness of the system for all future time periods. This study provides a platform for analysing the implication of different planning and management of Masinga dam and suggests that careful consideration should be given to account for growing municipal needs and irrigation schemes in both the immediate and the associated Tana River basin.

  11. Reliability Index for Reinforced Concrete Frames using Nonlinear Pushover and Dynamic Analysis

    Ahmad A. Fallah


    Full Text Available In the conventional design and analysis methods affecting parameters loads, materials' strength, etc are not set as probable variables. Safety factors in the current Codes and Standards are usually obtained on the basis of judgment and experience, which may be improper or uneconomical. In technical literature, a method based on nonlinear static analysis is suggested to set Reliability Index on strength of structural systems. In this paper, a method based on Nonlinear Dynamic analysis with rising acceleration (or Incremental Dynamic Analysis is introduced, the results of which are compared with those of the previous (Static Pushover Analysis method and two concepts namely Redundancy Strength and Redundancy Variations are proposed as an index to these impacts. The Redundancy Variation Factor and Redundancy Strength Factor indices for reinforced concrete frames with varying number of bays and stories and different ductility potentials are computed and ultimately, Reliability Index is determined using these two indices.

  12. Reliability Analysis of a Mono-Tower Platform

    Kirkegaard, Poul Henning; Enevoldsen, I.; Sørensen, John Dalsgaard;

    In this paper a reliability analysis of a Mono-tower platform is presented. The failure modes, considered, are yelding in the tube cross-sections, and fatigue failure in the butt welds. The fatigue failure mode is investigated with a fatigue model, where the fatigue strength is expressed through SN...... for the fatigue limit state is a significant failure mode for the Mono.tower platform. Further, it is shown for the fatigue failure mode the the largest contributions to the overall uncertainty are due to the damping ratio, the inertia coefficient, the stress concentration factor, the model uncertainties...

  13. Reliability Analysis of a Mono-Tower Platform

    Kirkegaard, Poul Henning; Enevoldsen, I.; Sørensen, John Dalsgaard;


    In this paper, a reliability analysis of a Mono-tower platform is presented. Te failure modes considered are yielding in the tube cross sections and fatigue failure in the butts welds. The fatigue failrue mode is investigated with a fatigue model, where the fatigue strength is expressed through SN...... that the fatigue limit state is a significant failure mode for the Mono-tower platform. Further, it is shown for the fatigue failure mode that the largest contributions to the overall uncertainty are due to the damping ratio, the inertia coefficient, the stress concentration factor, the model uncertainties...


    宋述芳; 吕震宙


    The saddlepoint approximation (SA) can directly estimate probability distribution of linear performance function in non-normal variables space and then calculate the failure probability of structure.Based on the property of SA, SA based reliability sensitivity analysis method is developed.For the nonlinear performance function, SA method needs the linearization of performance function firstly, but they neglect the influence of nonlinearity of performance function on the failure probability.So the reliability sensitivity analysis method based its improved method, named as SA based line sampling (LS), is presented.The reliability sensitivity can be estimated by the average of these partial derivatives of failure probabilities with respect to the distribution parameter of random variables, and the probabilities and sensitivities of the linear performance functions can be estimated by the SA in the non-normal variables space.By comparing basic concepts, implementations and results of illustrations, the following conclusions can be drawn, (1) SA based reliability sensitivity method is only acceptable for the linear performance function.The error mostly results from the linearization of the performance functions.(2) The SA based LS method can obtain the estimators of failure probability and reliability sensitivity, which converge to the actual value along with the increase of sample size.The SA based LS method considers the influence of nonlinearity of performance function on the failure probability and reliability sensitivity; therefore it has the wide applicability.%鞍点估计可以直接逼近非正态变量空间中线性功能函数概率分布,进而得出功能函数的失效概率.在此基础上进行了基于鞍点估计的可靠性灵敏度分析.对于非线性功能函数,尤其是强非线性功能函数,基于鞍点估计进行可靠性及灵敏度分析时存在较大的误差,为此建立了基于鞍点估计的改进方法--鞍点线抽样方法的

  15. Integration of human reliability analysis into the high consequence process

    Houghton, F.K.; Morzinski, J.


    When performing a hazards analysis (HA) for a high consequence process, human error often plays a significant role in the hazards analysis. In order to integrate human error into the hazards analysis, a human reliability analysis (HRA) is performed. Human reliability is the probability that a person will correctly perform a system-required activity in a required time period and will perform no extraneous activity that will affect the correct performance. Even though human error is a very complex subject that can only approximately be addressed in risk assessment, an attempt must be made to estimate the effect of human errors. The HRA provides data that can be incorporated in the hazard analysis event. This paper will discuss the integration of HRA into a HA for the disassembly of a high explosive component. The process was designed to use a retaining fixture to hold the high explosive in place during a rotation of the component. This tool was designed as a redundant safety feature to help prevent a drop of the explosive. This paper will use the retaining fixture to demonstrate the following HRA methodology`s phases. The first phase is to perform a task analysis. The second phase is the identification of the potential human, both cognitive and psychomotor, functions performed by the worker. During the last phase the human errors are quantified. In reality, the HRA process is an iterative process in which the stages overlap and information gathered in one stage may be used to refine a previous stage. The rationale for the decision to use or not use the retaining fixture and the role the HRA played in the decision will be discussed.

  16. Planning of operation & maintenance using risk and reliability based methods

    Florian, Mihai; Sørensen, John Dalsgaard


    Operation and maintenance (OM) of offshore wind turbines contributes with a substantial part of the total levelized cost of energy (LCOE). The objective of this paper is to present an application of risk- and reliability-based methods for planning of OM. The theoretical basis is presented...... and illustrated by an example, namely for planning of inspections and maintenance of wind turbine blades. A life-cycle approach is used where the total expected cost in the remaining lifetime is minimized. This maintenance plan is continuously updated during the lifetime using information from previous...... inspections and from condition monitoring with time intervals between inspections and maintenance / repair options as the decision parameters....

  17. 大五人格问卷(BFI-44)信度元分析--基于信度概化方法%A Reliability Meta-Analysis for 44 Items Big Five Inventory:Based on the Reliability Generalization Methodology

    黎红艳; 徐建平; 陈基越; 范业鑫


    Based on Reliability Generalization (RG) approach, this meta-analysis study focused on 85 English papers chosen from 782 papers (in both English and Chinese) about 44-Item Big Five Inventory (BFI-44) published in the past 24 years (1991~2014). This study analyzed the amount of variability in Cronbach's coefficient alpha of every dimension in BFI-44 and examined predictor variables, including sample size, subjects’ nationality, test language, average age and gender ratio, which were used for further investigation of their impact on the reliability of BFI-44 by using regression analysis. The study results showed that the Cronbach's coefficient alpha of each dimension reach nearly 0.8. The sample size, nationality and gender ratio variables influence BFI-44 dimensions on different levels. There are two suggestions for the use of the BFI-44. First, researchers should report the Cronbach's coefficient alpha of his/her own samples to avoid the reliability induction error;secondly, researchers should pay attention to the effect of sample size, nationality and gender ratio on Cronbach's coefficient alpha.%查询了1991~2014近24年发表的782篇BFI-44中、英文文献,最终筛选出85篇英文文献,采用信度概化方法对其进行了元分析。分析考察了BFI-44各维度的α系数值的分布与变化范围,并以样本量、国籍、测验语言版本、平均年龄、男女比例作为预测变量,通过回归分析探究了影响BFI-44信度水平的因素。结果显示 BFI-44各维度α系数均接近0.8;样本量、国籍、男女比例对各维度的信度水平有不同程度的影响。建议在应用BFI-44测验时,要报告BFI-44当前测试样本的α系数,忌犯“信度引入”错误,同时应注意样本量、文化差异、被试比例对α系数的影响。

  18. Reliability-Based Structural Optimization of Wave Energy Converters

    Simon Ambühl


    Full Text Available More and more wave energy converter (WEC concepts are reaching prototypelevel. Once the prototype level is reached, the next step in order to further decrease thelevelized cost of energy (LCOE is optimizing the overall system with a focus on structuraland maintenance (inspection costs, as well as on the harvested power from the waves.The target of a fully-developed WEC technology is not maximizing its power output,but minimizing the resulting LCOE. This paper presents a methodology to optimize thestructural design of WECs based on a reliability-based optimization problem and the intentto maximize the investor’s benefits by maximizing the difference between income (e.g., fromselling electricity and the expected expenses (e.g., structural building costs or failure costs.Furthermore, different development levels, like prototype or commercial devices, may havedifferent main objectives and will be located at different locations, as well as receive varioussubsidies. These points should be accounted for when performing structural optimizationsof WECs. An illustrative example on the gravity-based foundation of the Wavestar deviceis performed showing how structural design can be optimized taking target reliability levelsand different structural failure modes due to extreme loads into account.

  19. Generic Reliability-Based Inspection Planning for Fatigue Sensitive Details

    Sørensen, John Dalsgaard; Straub, Daniel; Faber, Michael Havbro


    of fatigue sensitive details in fixed offshore steel jacket platforms and FPSO ship structures. Inspection and maintenance activities are planned such that code based requirements to the safety of personnel and environment for the considered structure are fulfilled and at the same time such that the overall......The generic approach for planning of in-service NDT inspections is extended to cover the case where the fatigue load is modified during the design lifetime of the structure. Generic reliability-based inspection planning has been developed as a practical approach to perform inspection planning...... expected costs for design, inspections, repairs and failures are minimized. The method is based on the assumption of “no-finds” of cracks during inspections. Each fatigue sensitive detail is categorized according to their type of details (SN curves), FDF values, RSR values, inspection, repair and failure...

  20. Reliability Analysis of Timber Structures through NDT Data Upgrading

    Sousa, Hélder; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning

    for reliability calculation. In chapter 4, updating methods are conceptualized and defined. Special attention is drawn upon Bayesian methods and its implementation. Also a topic for updating based in inspection of deterioration is provided. State of the art definitions and proposed measurement indices......The first part of this document presents, in chapter 2, a description of timber characteristics and common used NDT and MDT for timber elements. Stochastic models for timber properties and damage accumulation models are also referred. According to timber’s properties a framework is proposed...

  1. A disjoint algorithm for seismic reliability analysis of lifeline networks


    The algorithm is based on constructing a disjoin kg t set of the minimal paths in a network system. In this paper,cubic notation was used to describe the logic function of a network in a well-balanced state, and then the sharp-product operation was used to construct the disjoint minimal path set of the network. A computer program has been developed, and when combined with decomposition technology, the reliability of a general lifeline network can be effectively and automatically calculated.

  2. Inclusion of fatigue effects in human reliability analysis

    Griffith, Candice D. [Vanderbilt University, Nashville, TN (United States); Mahadevan, Sankaran, E-mail: [Vanderbilt University, Nashville, TN (United States)


    The effect of fatigue on human performance has been observed to be an important factor in many industrial accidents. However, defining and measuring fatigue is not easily accomplished. This creates difficulties in including fatigue effects in probabilistic risk assessments (PRA) of complex engineering systems that seek to include human reliability analysis (HRA). Thus the objectives of this paper are to discuss (1) the importance of the effects of fatigue on performance, (2) the difficulties associated with defining and measuring fatigue, (3) the current status of inclusion of fatigue in HRA methods, and (4) the future directions and challenges for the inclusion of fatigue, specifically sleep deprivation, in HRA. - Highlights: >We highlight the need for fatigue and sleep deprivation effects on performance to be included in human reliability analysis (HRA) methods. Current methods do not explicitly include sleep deprivation effects. > We discuss the difficulties in defining and measuring fatigue. > We review sleep deprivation research, and discuss the limitations and future needs of the current HRA methods.

  3. Multi-objective reliability-based optimization with stochastic metamodels.

    Coelho, Rajan Filomeno; Bouillard, Philippe


    This paper addresses continuous optimization problems with multiple objectives and parameter uncertainty defined by probability distributions. First, a reliability-based formulation is proposed, defining the nondeterministic Pareto set as the minimal solutions such that user-defined probabilities of nondominance and constraint satisfaction are guaranteed. The formulation can be incorporated with minor modifications in a multiobjective evolutionary algorithm (here: the nondominated sorting genetic algorithm-II). Then, in the perspective of applying the method to large-scale structural engineering problems--for which the computational effort devoted to the optimization algorithm itself is negligible in comparison with the simulation--the second part of the study is concerned with the need to reduce the number of function evaluations while avoiding modification of the simulation code. Therefore, nonintrusive stochastic metamodels are developed in two steps. First, for a given sampling of the deterministic variables, a preliminary decomposition of the random responses (objectives and constraints) is performed through polynomial chaos expansion (PCE), allowing a representation of the responses by a limited set of coefficients. Then, a metamodel is carried out by kriging interpolation of the PCE coefficients with respect to the deterministic variables. The method has been tested successfully on seven analytical test cases and on the 10-bar truss benchmark, demonstrating the potential of the proposed approach to provide reliability-based Pareto solutions at a reasonable computational cost.

  4. Current Human Reliability Analysis Methods Applied to Computerized Procedures

    Ronald L. Boring


    Computerized procedures (CPs) are an emerging technology within nuclear power plant control rooms. While CPs have been implemented internationally in advanced control rooms, to date no US nuclear power plant has implemented CPs in its main control room (Fink et al., 2009). Yet, CPs are a reality of new plant builds and are an area of considerable interest to existing plants, which see advantages in terms of enhanced ease of use and easier records management by omitting the need for updating hardcopy procedures. The overall intent of this paper is to provide a characterization of human reliability analysis (HRA) issues for computerized procedures. It is beyond the scope of this document to propose a new HRA approach or to recommend specific methods or refinements to those methods. Rather, this paper serves as a review of current HRA as it may be used for the analysis and review of computerized procedures.

  5. Transient Reliability Analysis Capability Developed for CARES/Life

    Nemeth, Noel N.


    The CARES/Life software developed at the NASA Glenn Research Center provides a general-purpose design tool that predicts the probability of the failure of a ceramic component as a function of its time in service. This award-winning software has been widely used by U.S. industry to establish the reliability and life of a brittle material (e.g., ceramic, intermetallic, and graphite) structures in a wide variety of 21st century applications.Present capabilities of the NASA CARES/Life code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code can compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth failure conditions CARES/Life can handle sustained and linearly increasing time-dependent loads, whereas in cyclic fatigue applications various types of repetitive constant-amplitude loads can be accounted for. However, in real applications applied loads are rarely that simple but vary with time in more complex ways such as engine startup, shutdown, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. A methodology has now been developed to allow the CARES/Life computer code to perform reliability analysis of ceramic components undergoing transient thermal and mechanical loading. This means that CARES/Life will be able to analyze finite element models of ceramic components that simulate dynamic engine operating conditions. The methodology developed is generalized to account for material property variation (on strength distribution and fatigue) as a function of temperature. This allows CARES/Life to analyze components undergoing rapid temperature change in other words, components undergoing thermal shock. In addition, the capability has

  6. Reliability analysis of production ships with emphasis on load combination and ultimate strength

    Wang, Xiaozhi


    This thesis deals with ultimate strength and reliability analysis of offshore production ships, accounting for stochastic load combinations, using a typical North Sea production ship for reference. A review of methods for structural reliability analysis is presented. Probabilistic methods are established for the still water and vertical wave bending moments. Linear stress analysis of a midships transverse frame is carried out, four different finite element models are assessed. Upon verification of the general finite element code ABAQUS with a typical ship transverse girder example, for which test results are available, ultimate strength analysis of the reference transverse frame is made to obtain the ultimate load factors associated with the specified pressure loads in Det norske Veritas Classification rules for ships and rules for production vessels. Reliability analysis is performed to develop appropriate design criteria for the transverse structure. It is found that the transverse frame failure mode does not seem to contribute to the system collapse. Ultimate strength analysis of the longitudinally stiffened panels is performed, accounting for the combined biaxial and lateral loading. Reliability based design of the longitudinally stiffened bottom and deck panels is accomplished regarding the collapse mode under combined biaxial and lateral loads. 107 refs., 76 refs., 37 tabs.

  7. Cost Optimal Reliability Based Inspection and Replacement Planning of Piping Subjected to CO2 Corrosion

    Hellevik, S. G.; Langen, I.; Sørensen, John Dalsgaard


    A methodology for cost optimal reliability based inspection and replacement planning of piping subjected to CO2 corrosion is described. Both initial (design phase) and in-service planning are dealt with. The methodology is based on the application of methods for structural reliability analysis...... within the framework of Bayesian decision theory. The planning problem is formulated as an optimization problem where the expected lifetime costs are minimized with a constraint on the minimum acceptable reliability level. The optimization parameters are the number of inspections in the expected lifetime......, the inspection times and methods. In the design phase the nominal design wall thickness is also treated as an optimization parameter. The most important benefits gained through the application of the methodology are consistent evaluation of the consequences of different inspection and replacement plans...

  8. An approach for the reliability based design optimization of laminated composites

    Holdorf Lopez, Rafael; Lemosse, Didier; Souza de Cursi, José Eduardo; Rojas, Jhojan; El-Hami, Abdelkhalak


    This article aims at optimizing laminated composite plates taking into account uncertainties in the structural dimensions. As laminated composites require a global optimization tool, the Particle Swarm Optimization (PSO) method is employed. A new Reliability Based Design Optimization (RBDO) methodology based on safety factors is presented and coupled with PSO. Such safety factors are derived from the Karush-Kuhn-Tucker optimality conditions of the reliability index approach and eliminate the need for reliability analysis in RBDO. The plate weight minimization is the objective function of the optimization process. The results show that the coupling of the evolutionary algorithm with the safety-factor method proposed in this article successfully performs the RBDO of laminated composite structures.

  9. Analyzing reliability of seizure diagnosis based on semiology.

    Jin, Bo; Wu, Han; Xu, Jiahui; Yan, Jianwei; Ding, Yao; Wang, Z Irene; Guo, Yi; Wang, Zhongjin; Shen, Chunhong; Chen, Zhong; Ding, Meiping; Wang, Shuang


    This study aimed to determine the accuracy of seizure diagnosis by semiological analysis and to assess the factors that affect diagnostic reliability. A total of 150 video clips of seizures from 50 patients (each with three seizures of the same type) were observed by eight epileptologists, 12 neurologists, and 20 physicians (internists). The videos included 37 series of epileptic seizures, eight series of physiologic nonepileptic events (PNEEs), and five series of psychogenic nonepileptic seizures (PNESs). After observing each video, the doctors chose the diagnosis of epileptic seizures or nonepileptic events for the patient; if the latter was chosen, they further chose the diagnosis of PNESs or PNEEs. The overall diagnostic accuracy rate for epileptic seizures and nonepileptic events increased from 0.614 to 0.660 after observations of all three seizures (p semiological diagnosis of seizures is greatly affected by the seizure type as well as the doctor's experience. Although the overall reliability is limited, it can be improved by observing more seizures. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Reliability analysis and prediction of mixed mode load using Markov Chain Model

    Nikabdullah, N.; Singh, S. S. K.; Alebrahim, R.; Azizi, M. A.; K, Elwaleed A.; Noorani, M. S. M.


    The aim of this paper is to present the reliability analysis and prediction of mixed mode loading by using a simple two state Markov Chain Model for an automotive crankshaft. The reliability analysis and prediction for any automotive component or structure is important for analyzing and measuring the failure to increase the design life, eliminate or reduce the likelihood of failures and safety risk. The mechanical failures of the crankshaft are due of high bending and torsion stress concentration from high cycle and low rotating bending and torsional stress. The Markov Chain was used to model the two states based on the probability of failure due to bending and torsion stress. In most investigations it revealed that bending stress is much serve than torsional stress, therefore the probability criteria for the bending state would be higher compared to the torsion state. A statistical comparison between the developed Markov Chain Model and field data was done to observe the percentage of error. The reliability analysis and prediction was derived and illustrated from the Markov Chain Model were shown in the Weibull probability and cumulative distribution function, hazard rate and reliability curve and the bathtub curve. It can be concluded that Markov Chain Model has the ability to generate near similar data with minimal percentage of error and for a practical application; the proposed model provides a good accuracy in determining the reliability for the crankshaft under mixed mode loading.

  11. Reliability analysis and prediction of mixed mode load using Markov Chain Model

    Nikabdullah, N. [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia and Institute of Space Science (ANGKASA), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (Malaysia); Singh, S. S. K.; Alebrahim, R.; Azizi, M. A. [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (Malaysia); K, Elwaleed A. [Institute of Space Science (ANGKASA), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (Malaysia); Noorani, M. S. M. [School of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (Malaysia)


    The aim of this paper is to present the reliability analysis and prediction of mixed mode loading by using a simple two state Markov Chain Model for an automotive crankshaft. The reliability analysis and prediction for any automotive component or structure is important for analyzing and measuring the failure to increase the design life, eliminate or reduce the likelihood of failures and safety risk. The mechanical failures of the crankshaft are due of high bending and torsion stress concentration from high cycle and low rotating bending and torsional stress. The Markov Chain was used to model the two states based on the probability of failure due to bending and torsion stress. In most investigations it revealed that bending stress is much serve than torsional stress, therefore the probability criteria for the bending state would be higher compared to the torsion state. A statistical comparison between the developed Markov Chain Model and field data was done to observe the percentage of error. The reliability analysis and prediction was derived and illustrated from the Markov Chain Model were shown in the Weibull probability and cumulative distribution function, hazard rate and reliability curve and the bathtub curve. It can be concluded that Markov Chain Model has the ability to generate near similar data with minimal percentage of error and for a practical application; the proposed model provides a good accuracy in determining the reliability for the crankshaft under mixed mode loading.

  12. 基于小g函数法的客户侧供电可靠性分析的研究%Power Supply Reliability Analysis on Customer Side Based on Small g Function Method

    梁瑞莹; 黄玉昆


    针对目前我国对于供电可靠性只统计到中压客户,并不能全面反映各类用电客户实际的供电可靠性的缺陷,为了找出计及中压与计及低压两者之间供电可靠性的差异及其变化的规律,本文对低压客户侧供电可靠性的主要评价指标、基础数据的建立及各类停电数据的采集进行了分析,提出了采用“小g函数法”进行差异化分析,且以仿真数据输入的方式计算了同一外部环境和停电事件下的两种可靠性指标,经分析比较后得出了计及中、低压客户的供电可靠性指标变化差异的规律,为计及低压客户供电可靠性计算方式提供了理论依据.%In our country, it only counts medium voltage customers for power supply reliability, not fully reflect the defects of actual power supply reliability of various types of electricity customers. In order to find out the differences of power supply reliability between inclusive medium voltage and low voltage as well as the changing law, this paper made analysis on main evaluation index of the power supply reliability of the low voltage customer side, the establishment of the basic data and collection of various types of power outage data, and proposed to use "small g function method" to conduct gap analysis, and calculated two kinds of reliability index under the same external environment and the power outage with the way of simulation data input, through the comparative analysis, it gets the law of difference of changing in power supply reliability of inclusive mid-voltage and low-voltage customers, providing a theoretical basis for calculation way of power supply reliability inclusive low-voltage customer supply reliability.

  13. Productivity enhancement and reliability through AutoAnalysis

    Garetto, Anthony; Rademacher, Thomas; Schulz, Kristian


    The decreasing size and increasing complexity of photomask features, driven by the push to ever smaller technology nodes, places more and more challenges on the mask house, particularly in terms of yield management and cost reduction. Particularly challenging for mask shops is the inspection, repair and review cycle which requires more time and skill from operators due to the higher number of masks required per technology node and larger nuisance defect counts. While the measurement throughput of the AIMS™ platform has been improved in order to keep pace with these trends, the analysis of aerial images has seen little advancement and remains largely a manual process. This manual analysis of aerial images is time consuming, dependent on the skill level of the operator and significantly contributes to the overall mask manufacturing process flow. AutoAnalysis, the first application available for the FAVOR® platform, offers a solution to these problems by providing fully automated analysis of AIMS™ aerial images. Direct communication with the AIMS™ system allows automated data transfer and analysis parallel to the measurements. User defined report templates allow the relevant data to be output in a manner that can be tailored to various internal needs and support the requests of your customers. Productivity is significantly improved due to the fast analysis, operator time is saved and made available for other tasks and reliability is no longer a concern as the most defective region is always and consistently captured. In this paper the concept and approach of AutoAnalysis will be presented as well as an update to the status of the project. The benefits arising from the use of AutoAnalysis will be discussed in more detail and a study will be performed in order to demonstrate.

  14. Reliability of metalloceramic and zirconia-based ceramic crowns.

    Silva, N R F A; Bonfante, E A; Zavanelli, R A; Thompson, V P; Ferencz, J L; Coelho, P G


    Despite the increasing utilization of all-ceramic crown systems, their mechanical performance relative to that of metal ceramic restorations (MCR) has yet to be determined. This investigation tested the hypothesis that MCR present higher reliability over two Y-TZP all-ceramic crown systems under mouth-motion fatigue conditions. A CAD-based tooth preparation with the average dimensions of a mandibular first molar was used as a master die to fabricate all restorations. One 0.5-mm Pd-Ag and two Y-TZP system cores were veneered with 1.5 mm porcelain. Crowns were cemented onto aged (60 days in water) composite (Z100, 3M/ESPE) reproductions of the die. Mouth-motion fatigue was performed, and use level probability Weibull curves were determined. Failure modes of all systems included chipping or fracture of the porcelain veneer initiating at the indentation site. Fatigue was an acceleration factor for all-ceramic systems, but not for the MCR system. The latter presented significantly higher reliability under mouth-motion cyclic mechanical testing.

  15. ERP Reliability Analysis (ERA) Toolbox: An open-source toolbox for analyzing the reliability of event-related brain potentials.

    Clayson, Peter E; Miller, Gregory A


    Generalizability theory (G theory) provides a flexible, multifaceted approach to estimating score reliability. G theory's approach to estimating score reliability has important advantages over classical test theory that are relevant for research using event-related brain potentials (ERPs). For example, G theory does not require parallel forms (i.e., equal means, variances, and covariances), can handle unbalanced designs, and provides a single reliability estimate for designs with multiple sources of error. This monograph provides a detailed description of the conceptual framework of G theory using examples relevant to ERP researchers, presents the algorithms needed to estimate ERP score reliability, and provides a detailed walkthrough of newly-developed software, the ERP Reliability Analysis (ERA) Toolbox, that calculates score reliability using G theory. The ERA Toolbox is open-source, Matlab software that uses G theory to estimate the contribution of the number of trials retained for averaging, group, and/or event types on ERP score reliability. The toolbox facilitates the rigorous evaluation of psychometric properties of ERP scores recommended elsewhere in this special issue.

  16. Reliability analysis and updating of deteriorating systems with subset simulation

    Schneider, Ronald; Thöns, Sebastian; Straub, Daniel


    Bayesian updating of the system deterioration model. The updated system reliability is then obtained through coupling the updated deterioration model with a probabilistic structural model. The underlying high-dimensional structural reliability problems are solved using subset simulation, which...

  17. Reliability Analysis of Piezoelectric Truss Structures Under Joint Action of Electric and Mechanical Loading

    YANG Duo-he; AN Wei-guang; ZHU Rong-rong; MIAO Han


    Based on the finite element method(FEM) for the dynamical analysis of piezoelectric truss structures, the expressions of safety margins of strength fracture and damage electric field in the structure element are given considering electromechanical coupling effect under the joint action of electric and mechanical load. By importing the stochastic FEM,reliability of piezoelectric truss structures is analyzed by solving for partial derivative in the process of solving dynamical response of structure system with mode-superposition method. The influence of electromechanical coupling effect to reliability index is then analyzed through an example.

  18. Signal Quality Outage Analysis for Ultra-Reliable Communications in Cellular Networks

    Gerardino, Guillermo Andrés Pocovi; Alvarez, Beatriz Soret; Lauridsen, Mads


    , we investigate the potential of several techniques to combat these main threats. The analysis shows that traditional microscopic multiple-input multiple-output schemes with 2x2 or 4x4 antenna configurations are not enough to fulfil stringent reliability requirements. It is revealed how such antenna...... schemes must be complemented with macroscopic diversity as well as interference management techniques in order to ensure the necessary SINR outage performance. Based on the obtained performance results, it is discussed which of the feasible options fulfilling the ultra-reliable criteria are most promising...

  19. Suitability Analysis of Continuous-Use Reliability Growth Projection Models


    exists for all types, shapes, and sizes. The primary focus of this study is a comparison of reliability growth projection models designed for...requirements to use reliability growth models, recent studies have noted trends in reliability failures throughout the DoD. In [14] Dr. Michael a strict exponential distribu- tion was used to stay within their assumptions. In reality, however, reliability growth models often must be used

  20. Analysis of the Kinematic Accuracy Reliability of a 3-DOF Parallel Robot Manipulator

    Guohua Cui


    Full Text Available Kinematic accuracy reliability is an important performance index in the evaluation of mechanism quality. By using a 3- DOF 3-PUU parallel robot manipulator as the research object, the position and orientation error model was derived by mapping the relation between the input and output of the mechanism. Three error sensitivity indexes that evaluate the kinematic accuracy of the parallel robot manipulator were obtained by adapting the singular value decomposition of the error translation matrix. Considering the influence of controllable and uncontrollable factors on the kinematic accuracy, the mathematical model of reliability based on random probability was employed. The measurement and calculation method for the evaluation of the mechanism’s kinematic reliability level was also provided. By analysing the mechanism’s errors and reliability, the law of surface error sensitivity for the location and structure parameters was obtained. The kinematic reliability of the parallel robot manipulator was statistically computed on the basis of the Monte Carlo simulation method. The reliability analysis of kinematic accuracy provides a theoretical basis for design optimization and error compensation.

  1. Markov Chain Modelling of Reliability Analysis and Prediction under Mixed Mode Loading

    SINGH Salvinder; ABDULLAH Shahrum; NIK MOHAMED Nik Abdullah; MOHD NOORANI Mohd Salmi


    The reliability assessment for an automobile crankshaft provides an important understanding in dealing with the design life of the component in order to eliminate or reduce the likelihood of failure and safety risks. The failures of the crankshafts are considered as a catastrophic failure that leads towards a severe failure of the engine block and its other connecting subcomponents. The reliability of an automotive crankshaft under mixed mode loading using the Markov Chain Model is studied. The Markov Chain is modelled by using a two-state condition to represent the bending and torsion loads that would occur on the crankshaft. The automotive crankshaft represents a good case study of a component under mixed mode loading due to the rotating bending and torsion stresses. An estimation of the Weibull shape parameter is used to obtain the probability density function, cumulative distribution function, hazard and reliability rate functions, the bathtub curve and the mean time to failure. The various properties of the shape parameter is used to model the failure characteristic through the bathtub curve is shown. Likewise, an understanding of the patterns posed by the hazard rate onto the component can be used to improve the design and increase the life cycle based on the reliability and dependability of the component. The proposed reliability assessment provides an accurate, efficient, fast and cost effective reliability analysis in contrast to costly and lengthy experimental techniques.

  2. Reliability Analysis of Distributed Grid-connected Photovoltaic System Monitoring Network

    Fu Zhixin


    Full Text Available A large amount of distributed grid-connected Photovoltaic systems have brought new challenges to the dispatching of power network. Real-time monitoring the PV system can efficiently help improve the ability of power network to accept and control the distributed PV systems, and thus mitigate the impulse on the power network imposed by the uncertainty of its power output. To study the reliability of distributed PV monitoring network, it is of great significance to look for a method to build a highly reliable monitoring system, analyze the weak links and key nodes of its monitoring performance in improving the performance of the monitoring network. Firstly a reliability model of PV system was constructed based on WSN technology. Then, in view of the dynamic characteristics of the network’s reliability, fault tree analysis was used to judge any possible reasons that cause the failure of the network and logical relationship between them. Finally, the reliability of the monitoring network was analyzed to figure out the weak links and key nodes. This paper provides guidance to build a stable and reliable monitoring network of a distributed PV system.

  3. An Efficient Approach for the Reliability Analysis of Phased-Mission Systems with Dependent Failures

    Xing, Liudong; Meshkat, Leila; Donahue, Susan K.


    We consider the reliability analysis of phased-mission systems with common-cause failures in this paper. Phased-mission systems (PMS) are systems supporting missions characterized by multiple, consecutive, and nonoverlapping phases of operation. System components may be subject to different stresses as well as different reliability requirements throughout the course of the mission. As a result, component behavior and relationships may need to be modeled differently from phase to phase when performing a system-level reliability analysis. This consideration poses unique challenges to existing analysis methods. The challenges increase when common-cause failures (CCF) are incorporated in the model. CCF are multiple dependent component failures within a system that are a direct result of a shared root cause, such as sabotage, flood, earthquake, power outage, or human errors. It has been shown by many reliability studies that CCF tend to increase a system's joint failure probabilities and thus contribute significantly to the overall unreliability of systems subject to CCF.We propose a separable phase-modular approach to the reliability analysis of phased-mission systems with dependent common-cause failures as one way to meet the above challenges in an efficient and elegant manner. Our methodology is twofold: first, we separate the effects of CCF from the PMS analysis using the total probability theorem and the common-cause event space developed based on the elementary common-causes; next, we apply an efficient phase-modular approach to analyze the reliability of the PMS. The phase-modular approach employs both combinatorial binary decision diagram and Markov-chain solution methods as appropriate. We provide an example of a reliability analysis of a PMS with both static and dynamic phases as well as CCF as an illustration of our proposed approach. The example is based on information extracted from a Mars orbiter project. The reliability model for this orbiter considers

  4. Reliability Analysis of Large Power Equipment Based on Nonlinear Forecast%基于非线性预估的大规模电力设备可靠性分析

    吴丽贤; 陈科师


    针对电力设备一旦规模较为庞大,会出现较为复杂的运行过程,使得信号分析过程中,非线性故障信号与其他故障信号失联。造成电力设备可靠性分析出现较大偏差。为此提出一种以无限传感网络配合故障估计分析算法的大规模电力设备可靠性分析系统的优化设计方案。通过运用无线传感网络对电力设备接口信号的快速采集,对其进行准确的非线性预测性估计,保证系统对电力设备可靠性分析的准确性。实验结果证明,优化后的系统对电力设备可靠性分析较为准确,性能有所提高。%In view of the power equipment once the scale is relatively large, signal analysis process, the nonlinear fault signal and other signal is lost. Electric power equipment reliability analysis appear large deviation. Therefore put forward a kind of fault estimation with infinite sensor network analysis algorithm of optimizing design scheme of large power e-quipment reliability analysis system. The wireless sensor network is used to power equipment interface signal fast acqui-sition, carry on the accurate nonlinear predictive estimate, it ensured the accuracy of the system for power equipment re-liability analysis. The experimental results show that the optimized system for power equipment reliability analysis is rela-tively accurate, the performance improved.

  5. Spatial reliability analysis of a wind turbine blade cross section subjected to multi-axial extreme loading

    Dimitrov, Nikolay Krasimirov; Bitsche, Robert; Blasques, José Pedro Albergaria Amaral


    properties, progressive material failure, and system reliability effects. An example analysis of reliability against material failure is demonstrated for a blade cross section. Based on the study we discuss the implications of using a system reliability approach, the effect of spatial correlation length......This paper presents a methodology for structural reliability analysis of wind turbine blades. The study introduces several novel elements by taking into account loading direction using a multiaxial probabilistic load model, considering random material strength, spatial correlation between material......, type of material degradation algorithm, and reliability methods on the system failure probability, as well as the main factors that have an influence on the reliability. (C) 2017 Elsevier Ltd. All rights reserved....

  6. Reliability analysis of digital protection system based on interval theory%基于区间理论的数字化保护系统可靠性分析

    肖飞; 吕飞鹏


    This paper puts forward two new programs for improving the redundancy configuration of traditional digital protection, and takes advantage of the GO methodology for modeling analysis. Considering the uncertainty of initial data of digital protection, interval values are used to revise them and interval evaluation is conducted based on the reliability model. Since the interval values contain the uncertain risks, the results are more scientific and practical. The proposed method is testified by an example and is proved to be effective.%  对传统的数字化保护系统冗余配置,提出了两种新的改进方案,并利用 GO 法进行建模分析。考虑数字化保护系统可靠性原始数据的不确定性,采用区间数值的方法来对原始数据进行修正,并结合提出的可靠性模型,对保护系统进行区间评估。由于区间值结果包含了不确定的风险因素,因此得到结果更科学、更符合实际。最后的算例对所提方法进行了验证,说明了该方法的有效性。

  7. New Mathematical Derivations Applicable to Safety and Reliability Analysis

    Cooper, J.A.; Ferson, S.


    Boolean logic expressions are often derived in safety and reliability analysis. Since the values of the operands are rarely exact, accounting for uncertainty with the tightest justifiable bounds is important. Accurate determination of result bounds is difficult when the inputs have constraints. One example of a constraint is that an uncertain variable that appears multiple times in a Boolean expression must always have the same value, although the value cannot be exactly specified. A solution for this repeated variable problem is demonstrated for two Boolean classes. The classes, termed functions with unate variables (including, but not limited to unate functions), and exclusive-or functions, frequently appear in Boolean equations for uncertain outcomes portrayed by logic trees (event trees and fault trees).

  8. Applicability of simplified human reliability analysis methods for severe accidents

    Boring, R.; St Germain, S. [Idaho National Lab., Idaho Falls, Idaho (United States); Banaseanu, G.; Chatri, H.; Akl, Y. [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada)


    Most contemporary human reliability analysis (HRA) methods were created to analyse design-basis accidents at nuclear power plants. As part of a comprehensive expansion of risk assessments at many plants internationally, HRAs will begin considering severe accident scenarios. Severe accidents, while extremely rare, constitute high consequence events that significantly challenge successful operations and recovery. Challenges during severe accidents include degraded and hazardous operating conditions at the plant, the shift in control from the main control room to the technical support center, the unavailability of plant instrumentation, and the need to use different types of operating procedures. Such shifts in operations may also test key assumptions in existing HRA methods. This paper discusses key differences between design basis and severe accidents, reviews efforts to date to create customized HRA methods suitable for severe accidents, and recommends practices for adapting existing HRA methods that are already being used for HRAs at the plants. (author)

  9. Time-dependent reliability analysis and condition assessment of structures

    Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States)


    Structures generally play a passive role in assurance of safety in nuclear plant operation, but are important if the plant is to withstand the effect of extreme environmental or abnormal events. Relative to mechanical and electrical components, structural systems and components would be difficult and costly to replace. While the performance of steel or reinforced concrete structures in service generally has been very good, their strengths may deteriorate during an extended service life as a result of changes brought on by an aggressive environment, excessive loading, or accidental loading. Quantitative tools for condition assessment of aging structures can be developed using time-dependent structural reliability analysis methods. Such methods provide a framework for addressing the uncertainties attendant to aging in the decision process.

  10. Reliability analysis for the quench detection in the LHC machine

    Denz, R; Vergara-Fernández, A


    The Large Hadron Collider (LHC) will incorporate a large amount of superconducting elements that require protection in case of a quench. Key elements in the quench protection system are the electronic quench detectors. Their reliability will have an important impact on the down time as well as on the operational cost of the collider. The expected rates of both false and missed quenches have been computed for several redundant detection schemes. The developed model takes account of the maintainability of the system to optimise the frequency of foreseen checks, and evaluate their influence on the performance of different detection topologies. Seen the uncertainty of the failure rate of the components combined with the LHC tunnel environment, the study has been completed with a sensitivity analysis of the results. The chosen detection scheme and the maintainability strategy for each detector family are given.

  11. Reliability, compliance, and security in web-based course assessments

    Scott Bonham


    Full Text Available Pre- and postcourse assessment has become a very important tool for education research in physics and other areas. The web offers an attractive alternative to in-class paper administration, but concerns about web-based administration include reliability due to changes in medium, student compliance rates, and test security, both question leakage and utilization of web resources. An investigation was carried out in introductory astronomy courses comparing pre- and postcourse administration of assessments using the web and on paper. Overall no difference was seen in performance due to the medium. Compliance rates fluctuated greatly, and factors that seemed to produce higher rates are identified. Notably, email reminders increased compliance by 20%. Most of the 559 students complied with requests to not copy, print, or save questions nor use web resources; about 1% did copy some question text and around 2% frequently used other windows or applications while completing the assessment.

  12. Reliable routing mechanism based on neighbor stability for MANET

    WU Da-peng; WU Mu-qing; ZHEN Yan


    One critical issue for routing in mobile Ad-hoc networks (MANETs) is how to select a reliable path that can last longer because mobility may cause frequent breakdown in radio links. A novel routing mechanism based on link lifetime estimation is proposed in this article. In this mechanism, the node's received signal strength is obtained continuously by using Newton interpolation polynomial, and by method of middle value and interception, the reference points are selected to estimate the link lifetime. With the constraint of link lifetime and hop counts, the source nodes set up the route hop by hop. The simulations show that link lifetime can be predicted regardless of mobility pattern. Moreover, the route discovery times and packet drop ratio can be reduced by the proposed mechanism, and thus improving the performance of MANETs.

  13. Reliability, compliance, and security in web-based course assessments

    Scott Bonham


    Full Text Available Pre- and postcourse assessment has become a very important tool for education research in physics and other areas. The web offers an attractive alternative to in-class paper administration, but concerns about web-based administration include reliability due to changes in medium, student compliance rates, and test security, both question leakage and utilization of web resources. An investigation was carried out in introductory astronomy courses comparing pre- and postcourse administration of assessments using the web and on paper. Overall no difference was seen in performance due to the medium. Compliance rates fluctuated greatly, and factors that seemed to produce higher rates are identified. Notably, email reminders increased compliance by 20%. Most of the 559 students complied with requests to not copy, print, or save questions nor use web resources; about 1% did copy some question text and around 2% frequently used other windows or applications while completing the assessment.

  14. Reliability of Substation Protection System Based on IEC61850

    XIONG Xiaofu; YU Jun; LIU Xiaofang; SHEN Zhijan


    Although the new technology of protection and automation system of substation based on IEC61850 standard has developed rapidly in China, reliability measures depending on this tech- nology need to be further researched. By taking advantage of convenient information sharing, two kinds of new schemes, shared backup protection unit (SBPU) and signal backup (SB), have been proposed to solve the failure problem of protective devices and current/voltage transducers respec- tively, and the working principle of these two schemes are also described. Furthermore, the key technologies of on-line diagnosis of protective devices' failure and on-line status diagnosis of op- tical or electronic current/voltage transducers to realize the two schemes are proposed.

  15. Reliability estimation and remaining useful lifetime prediction for bearing based on proportional hazard model

    王鹭; 张利; 王学芝


    As the central component of rotating machine, the performance reliability assessment and remaining useful lifetime prediction of bearing are of crucial importance in condition-based maintenance to reduce the maintenance cost and improve the reliability. A prognostic algorithm to assess the reliability and forecast the remaining useful lifetime (RUL) of bearings was proposed, consisting of three phases. Online vibration and temperature signals of bearings in normal state were measured during the manufacturing process and the most useful time-dependent features of vibration signals were extracted based on correlation analysis (feature selection step). Time series analysis based on neural network, as an identification model, was used to predict the features of bearing vibration signals at any horizons (feature prediction step). Furthermore, according to the features, degradation factor was defined. The proportional hazard model was generated to estimate the survival function and forecast the RUL of the bearing (RUL prediction step). The positive results show that the plausibility and effectiveness of the proposed approach can facilitate bearing reliability estimation and RUL prediction.

  16. A model for reliability analysis and calculation applied in an example from chemical industry

    Pejović Branko B.


    Full Text Available The subject of the paper is reliability design in polymerization processes that occur in reactors of a chemical industry. The designed model is used to determine the characteristics and indicators of reliability, which enabled the determination of basic factors that result in a poor development of a process. This would reduce the anticipated losses through the ability to control them, as well as enabling the improvement of the quality of production, which is the major goal of the paper. The reliability analysis and calculation uses the deductive method based on designing of a scheme for fault tree analysis of a system based on inductive conclusions. It involves the use standard logical symbols and rules of Boolean algebra and mathematical logic. The paper eventually gives the results of the work in the form of quantitative and qualitative reliability analysis of the observed process, which served to obtain complete information on the probability of top event in the process, as well as objective decision making and alternative solutions.

  17. The Seismic Reliability of Offshore Structures Based on Nonlinear Time History Analyses

    Hosseini, Mahmood; Karimiyani, Somayyeh; Ghafooripour, Amin; Jabbarzadeh, Mohammad Javad


    Regarding the past earthquakes damages to offshore structures, as vital structures in the oil and gas industries, it is important that their seismic design is performed by very high reliability. Accepting the Nonlinear Time History Analyses (NLTHA) as the most reliable seismic analysis method, in this paper an offshore platform of jacket type with the height of 304 feet, having a deck of 96 feet by 94 feet, and weighing 290 million pounds has been studied. At first, some Push-Over Analyses (POA) have been preformed to recognize the more critical members of the jacket, based on the range of their plastic deformations. Then NLTHA have been performed by using the 3-components accelerograms of 100 earthquakes, covering a wide range of frequency content, and normalized to three Peak Ground Acceleration (PGA) levels of 0.3 g, 0.65 g, and 1.0 g. By using the results of NLTHA the damage and rupture probabilities of critical member have been studied to assess the reliability of the jacket structure. Regarding that different structural members of the jacket have different effects on the stability of the platform, an "importance factor" has been considered for each critical member based on its location and orientation in the structure, and then the reliability of the whole structure has been obtained by combining the reliability of the critical members, each having its specific importance factor.

  18. Guidelines for reliability analysis of digital systems in PSA context. Phase 1 status report

    Authen, S.; Larsson, J. (Risk Pilot AB, Stockholm (Sweden)); Bjoerkman, K.; Holmberg, J.-E. (VTT, Helsingfors (Finland))


    Digital protection and control systems are appearing as upgrades in older nuclear power plants (NPPs) and are commonplace in new NPPs. To assess the risk of NPP operation and to determine the risk impact of digital system upgrades on NPPs, quantitative reliability models are needed for digital systems. Due to the many unique attributes of these systems, challenges exist in systems analysis, modeling and in data collection. Currently there is no consensus on reliability analysis approaches. Traditional methods have clearly limitations, but more dynamic approaches are still in trial stage and can be difficult to apply in full scale probabilistic safety assessments (PSA). The number of PSAs worldwide including reliability models of digital I and C systems are few. A comparison of Nordic experiences and a literature review on main international references have been performed in this pre-study project. The study shows a wide range of approaches, and also indicates that no state-of-the-art currently exists. The study shows areas where the different PSAs agree and gives the basis for development of a common taxonomy for reliability analysis of digital systems. It is still an open matter whether software reliability needs to be explicitly modelled in the PSA. The most important issue concerning software reliability is proper descriptions of the impact that software-based systems has on the dependence between the safety functions and the structure of accident sequences. In general the conventional fault tree approach seems to be sufficient for modelling reactor protection system kind of functions. The following focus areas have been identified for further activities: 1. Common taxonomy of hardware and software failure modes of digital components for common use 2. Guidelines regarding level of detail in system analysis and screening of components, failure modes and dependencies 3. Approach for modelling of CCF between components (including software). (Author)

  19. Reliablity analysis of gravity dams by response surface method

    Humar, Nina; Kryžanowski, Andrej; Brilly, Mitja; Schnabl, Simon


    A dam failure is one of the most important problems in dam industry. Since the mechanical behavior of dams is usually a complex phenomenon existing classical mathematical models are generally insufficient to adequately predict the dam failure and thus the safety of dams. Therefore, numerical reliability methods are often used to model such a complex mechanical phenomena. Thus, the main purpose of the present paper is to present the response surface method as a powerful mathematical tool used to study and foresee the dam safety considering a set of collected monitoring data. The derived mathematical model is applied to a case study, the Moste dam, which is the highest concrete gravity dam in Slovenia. Based on the derived model, the ambient/state variables are correlated with the dam deformation in order to gain a forecasting tool able to define the critical thresholds for dam management.

  20. Potential Negative Impact of DG on Reliability Index: A Study Based on Time-Domain Modeling

    Ran, Xuanchang

    This thesis presents an original insight of the negative impact of distributed generation on reliability index based on dynamic time-domain modeling. Models for essential power system components, such as protective devices and synchronous generators, were developed and tested. A 4 kV distribution loop which carries relatively high power demand was chosen for the analysis. The characteristic curves of all protective devices were extracted from utility database and applied to the time domain relay model. The performance of each device was investigated in details. The negative effect on reliability is due to the fuse opening caused by the installation of DG at the wrong location and inappropriate relay setup. Over 50% of the possible DG locations can produce an undesirable impact. The study conclusion is that there exists a significant potential for the installation of DG to negatively affect the reliability of power systems.

  1. A Study on Management Techniques of Power Telecommunication System by Reliability Analysis

    Lee, B.K.; Lee, B.S.; Woy, Y.H.; Oh, M.T.; Shin, M.T.; Kwan, O.G. [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, K.H.; Kim, Y.H.; Lee, W.T.; Park, Y.H.; Lee, J.J.; Park, H.S.; Choi, M.C.; Kim, J. [Korea Electrotechnology Research Inst., Changwon (Korea, Republic of)


    Power telecommunication network is being increased rapidly in that expansion of power facilities according to the growth of electric power supply. The requirement of power facility and office automation and importance of communication services make it to complex and confusing to operate. And, for the sake of correspond to the change of power telecommunication network, effective operation and management is called for urgently. Therefore, the object of this study is to establish total reliability analysis system based on dependability, maintainability, cost effectiveness and replenishment for keep up reasonable reliability, support economical maintenance and reasonable planning of facility investment. And it will make effective management and administration system and schemes for total reliability improvement. (author). 44 refs., figs.

  2. A hybrid algorithm for reliability analysis combining Kriging and subset simulation importance sampling

    Tong, Cao; Sun, Zhili; Zhao, Qianli; Wang, Qibin [Northeastern University, Shenyang (China); Wang, Shuang [Jiangxi University of Science and Technology, Ganzhou (China)


    To solve the problem of large computation when failure probability with time-consuming numerical model is calculated, we propose an improved active learning reliability method called AK-SSIS based on AK-IS algorithm. First, an improved iterative stopping criterion in active learning is presented so that iterations decrease dramatically. Second, the proposed method introduces Subset simulation importance sampling (SSIS) into the active learning reliability calculation, and then a learning function suitable for SSIS is proposed. Finally, the efficiency of AK-SSIS is proved by two academic examples from the literature. The results show that AK-SSIS requires fewer calls to the performance function than AK-IS, and the failure probability obtained from AK-SSIS is very robust and accurate. Then this method is applied on a spur gear pair for tooth contact fatigue reliability analysis.

  3. Reliability Analysis for Electric Multiple Units Based on Fault Tree Monte Carlo Method%基于故障树—蒙特卡洛方法的动车组可靠性分析

    胡川; 姚建伟


    建立CRH2型动车组系统及其走行子系统、牵引传动子系统、制动子系统、高压电器子系统、辅助供电子系统以及网络控制子系统的故障树,在此基础上运用蒙特卡洛方法和MATLAB软件,对动车组的可靠性进行仿真分析.结果表明:基于故障树分析的蒙特卡洛仿真方法能快速、准确地计算动车组整车的可靠性;当动车组各基本部件发生故障的概率服从指数分布时,整个动车组系统发生故障的概率也服从指数分布;动车组最重要的3个分系统依次为空气供给分系统、接地保护开关和高压设备箱分系统以及牵引传动分系统.%The fault trees of the CRH2 EMU system as well as its subsystems of running, traction drive, braking, high voltage apparatus, auxiliary power supply and network control were established. On that basis, Monte Carlo method and MATLAB software were applied to simulate and analyze the reliability of the EMU. The results indicate that, Monte Carlo simulation method which is based on fault tree analysis, can rapidly and accurately calculate the reliability of the whole EMU. If the fault probabilities of EMU various basic components obey exponential distribution, then does the fault probability of the whole EMU system. The three most important partial systems of the EMU are, in order, the air supply partial system, the grounding protection switch and high voltage equipment box partial system and traction drive partial system.

  4. 基于多失效模式的扭簧可靠性优化分析%Optimal Analysis of the Reliability for Torsion Spring Based on Multi-failure Modes

    王梅; 陈国定; 肖勇


    基于广义应力-广义强度分布干涉理论和单一失效模式下扭簧可靠性计算模型,建立了多失效模式下扭簧可靠度优化数学模型,采用规格化加权法进行各失效模式影响相同(等失效效应)和有差异(非等失效效应)两种情况下的扭簧可靠度计算.在给定扭簧结构和工况约束条件下,应用提出的计算模型和技术进行了失效模式影响相同和有差异的基于可靠度最大的扭簧结构优化,与非优化结构的扭簧可靠度的比较,以及这两种情况下的扭簧可靠度比较.结果表明,提出的可靠度优化模型和方法是可靠和有效的,对于航天工程中零部件的可靠性优化分析具有很好的借鉴作用.%Based on the general stress-intensity distribution of a broad interference theory and reliability model of a single failure mode, the torsion spring reliability optimization model was established under multi-failure mode. The normalized weighted method was used to solve the torsion spring reliability calculation under equal failure effect mode and unequal failure effect mode. Under given structure and constraint conditions of torsion spring, the best reliability optimization of torsion spring structure was done in the same failure mode (equal failure effect) and different failure mode (unequal failure effect) one using the proposed model and techniques. Under equal failure effect and unequal failure effect, compared with the torsion spring reliability of non-optimized structure, the proposed reliability optimization models and methods proposed are reliable, valid and good reference for the reliability optimization of the spacecraft components.

  5. Reliability-Based Marginal Cost Pricing Problem Case with Both Demand Uncertainty and Travelers’ Perception Errors

    Shaopeng Zhong


    Full Text Available Focusing on the first-best marginal cost pricing (MCP in a stochastic network with both travel demand uncertainty and stochastic perception errors within the travelers’ route choice decision processes, this paper develops a perceived risk-based stochastic network marginal cost pricing (PRSN-MCP model. Numerical examples based on an integrated method combining the moment analysis approach, the fitting distribution method, and the reliability measures are also provided to demonstrate the importance and properties of the proposed model. The main finding is that ignoring the effect of travel time reliability and travelers’ perception errors may significantly reduce the performance of the first-best MCP tolls, especially under high travelers’ confidence and network congestion levels. The analysis result could also enhance our understanding of (1 the effect of stochastic perception error (SPE on the perceived travel time distribution and the components of road toll; (2 the effect of road toll on the actual travel time distribution and its reliability measures; (3 the effect of road toll on the total network travel time distribution and its statistics; and (4 the effect of travel demand level and the value of reliability (VoR level on the components of road toll.

  6. Multi-Unit Considerations for Human Reliability Analysis

    St. Germain, S.; Boring, R.; Banaseanu, G.; Akl, Y.; Chatri, H.


    This paper uses the insights from the Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) methodology to help identify human actions currently modeled in the single unit PSA that may need to be modified to account for additional challenges imposed by a multi-unit accident as well as identify possible new human actions that might be modeled to more accurately characterize multi-unit risk. In identifying these potential human action impacts, the use of the SPAR-H strategy to include both errors in diagnosis and errors in action is considered as well as identifying characteristics of a multi-unit accident scenario that may impact the selection of the performance shaping factors (PSFs) used in SPAR-H. The lessons learned from the Fukushima Daiichi reactor accident will be addressed to further help identify areas where improved modeling may be required. While these multi-unit impacts may require modifications to a Level 1 PSA model, it is expected to have much more importance for Level 2 modeling. There is little currently written specifically about multi-unit HRA issues. A review of related published research will be presented. While this paper cannot answer all issues related to multi-unit HRA, it will hopefully serve as a starting point to generate discussion and spark additional ideas towards the proper treatment of HRA in a multi-unit PSA.

  7. Johnson Space Center's Risk and Reliability Analysis Group 2008 Annual Report

    Valentine, Mark; Boyer, Roger; Cross, Bob; Hamlin, Teri; Roelant, Henk; Stewart, Mike; Bigler, Mark; Winter, Scott; Reistle, Bruce; Heydorn,Dick


    The Johnson Space Center (JSC) Safety & Mission Assurance (S&MA) Directorate s Risk and Reliability Analysis Group provides both mathematical and engineering analysis expertise in the areas of Probabilistic Risk Assessment (PRA), Reliability and Maintainability (R&M) analysis, and data collection and analysis. The fundamental goal of this group is to provide National Aeronautics and Space Administration (NASA) decisionmakers with the necessary information to make informed decisions when evaluating personnel, flight hardware, and public safety concerns associated with current operating systems as well as with any future systems. The Analysis Group includes a staff of statistical and reliability experts with valuable backgrounds in the statistical, reliability, and engineering fields. This group includes JSC S&MA Analysis Branch personnel as well as S&MA support services contractors, such as Science Applications International Corporation (SAIC) and SoHaR. The Analysis Group s experience base includes nuclear power (both commercial and navy), manufacturing, Department of Defense, chemical, and shipping industries, as well as significant aerospace experience specifically in the Shuttle, International Space Station (ISS), and Constellation Programs. The Analysis Group partners with project and program offices, other NASA centers, NASA contractors, and universities to provide additional resources or information to the group when performing various analysis tasks. The JSC S&MA Analysis Group is recognized as a leader in risk and reliability analysis within the NASA community. Therefore, the Analysis Group is in high demand to help the Space Shuttle Program (SSP) continue to fly safely, assist in designing the next generation spacecraft for the Constellation Program (CxP), and promote advanced analytical techniques. The Analysis Section s tasks include teaching classes and instituting personnel qualification processes to enhance the professional abilities of our analysts

  8. Fuzzy Reliability Analysis of the Shaft of a Steam Turbine


    Field surveying shows that the failure of the steam turbine's coupling is due to fatigue that is caused by compound stress. Fuzzy mathematics was applied to get the membership function of the fatigue strength rule. A formula of fuzzy reliability of the coupling was derived and a theory of coupling's fuzzy reliability is set up. The calculating method of the fuzzy reliability is explained by an illustrative example.

  9. Reliability of videotaped observational gait analysis in patients with orthopedic impairments

    Brunnekreef, J.J.; Uden, C. van; Moorsel, S. van; Kooloos, J.G.M.


    BACKGROUND: In clinical practice, visual gait observation is often used to determine gait disorders and to evaluate treatment. Several reliability studies on observational gait analysis have been described in the literature and generally showed moderate reliability. However, patients with orthopedic

  10. An Efficient Variable Screening Method for Effective Surrogate Models for Reliability-Based Design Optimization


    reliability-based design optimization ( RBDO ) process, surrogate models are frequently used to reduce the number of simulations because analysis of a...the RBDO problem and thus mitigate the curse of dimensionality. Therefore, it is desirable to develop an efficient and effective variable...screening method for reduction of the dimension of the RBDO problem. In this paper, requirements of the variable screening method for deterministic design

  11. AP1000 In-Containment Pressure Over-limit ESF Actuation Reliability Analysis Based on DFM%基于DFM的AP1000壳内压力超限ESF驱动可靠性分析

    王志超; 王豪; 周赟


    This paper making use of Dynamic Flowgraph Methodology (DFM) which is the reliability analysis method proposed in (NRC) report NUREG/ CR-6465 to analyze the reliability of AP1000 nuclear power plant containment pressure over-limit safety feature facility (ESF) actuation system. This method reflects the impact of process input and output variable causal relationship, dynamic characteristics, component state variation and software logic to the system reliability, and organically combines the digital protect system and process system. The result of the analysis is the set of time-stamped Prime Implicant (PI) which has a highly important guiding significance to the further quantitative analysis and the improvement of the reliability of the system.%本文运用美国核管会(NRC)报告NUREG/CR-6465提出的动态流图(DFM)可靠性分析方法,以AP1000核电站安全壳压力超限专设安全设施(ESF)驱动系统为对象进行可靠性分析。该方法体现过变量输入输出的因果关系、动态特性、部件状态变化和软件逻辑对系统可靠性的影响,将数字化保护系统与工艺系统有机结合。其分析结果是带时间标签的质蕴含(PI)集合,对进一步地定量分析以及提高系统的可靠性具有很重要的指导意义。

  12. Dimensionality and reliability of the self-care of heart failure index scales: further evidence from confirmatory factor analysis.

    Barbaranelli, Claudio; Lee, Christopher S; Vellone, Ercole; Riegel, Barbara


    The Self-Care of Heart Failure Index (SCHFI) is used widely, but issues with reliability have been evident. Cronbach alpha coefficient is usually used to assess reliability, but this approach assumes a unidimensional scale. The purpose of this article is to address the dimensionality and internal consistency reliability of the SCHFI. This was a secondary analysis of data from 629 adults with heart failure enrolled in three separate studies conducted in the northeastern and northwestern United States. Following testing for scale dimensionality using confirmatory factor analysis, reliability was tested using coefficient alpha and alternative options. Confirmatory factor analysis demonstrated that: (a) the Self-Care Maintenance Scale has a multidimensional four-factor structure; (b) the Self-Care Management Scale has a two-factor structure, but the primary factors loaded on a common higher-order factor; and (c) the Self-Care Confidence Scale is unidimensional. Reliability estimates for the three scales, obtained with methods compatible with each scale's dimensionality, were adequate or high. The results of the analysis demonstrate that issues of dimensionality and reliability cannot be separated. Appropriate estimates of reliability that are consistent with the dimensionality of the scale must be used. In the case of the SCHFI, coefficient alpha should not be used to assess reliability of the self-care maintenance and the self-care management scales, due to their multidimensionality. When performing psychometric evaluations, we recommend testing dimensionality before assessing reliability, as well using multiple indices of reliability, such as model-based internal consistency, composite reliability, and omega and maximal reliability coefficients. © 2014 Wiley Periodicals, Inc.

  13. Wind energy Computerized Maintenance Management System (CMMS) : data collection recommendations for reliability analysis.

    Peters, Valerie A.; Ogilvie, Alistair; Veers, Paul S.


    This report addresses the general data requirements for reliability analysis of fielded wind turbines and other wind plant equipment. The report provides a list of the data needed to support reliability and availability analysis, and gives specific recommendations for a Computerized Maintenance Management System (CMMS) to support automated analysis. This data collection recommendations report was written by Sandia National Laboratories to address the general data requirements for reliability analysis of fielded wind turbines. This report is intended to help the reader develop a basic understanding of what data are needed from a Computerized Maintenance Management System (CMMS) and other data systems, for reliability analysis. The report provides: (1) a list of the data needed to support reliability and availability analysis; and (2) specific recommendations for a CMMS to support automated analysis. Though written for reliability analysis of wind turbines, much of the information is applicable to a wider variety of equipment and a wider variety of analysis and reporting needs.

  14. Iterative projection on critical states for reliability-based design optimization

    Croquet, R.; Lemosse, D.; Souza de Cursi, E.; El Hami, A.


    Reliability-Based Design Optimization (RBDO) has been developed to design structures that reach the best compromise between cost reduction and reliability by considering uncertainties. This is achieved by reformulating the initial optimization problem in order to introduce probabilistic constraints. Numerical evaluation of these constraints by direct approaches turns out to be difficult: estimation of probability of failure implies calculation of multidimensional integrals. The integrals often rely on complex models whose evaluation is time-consuming. In this article, the RBDO framework is used to propose a new approach. For this purpose, a method to project a deterministic optimal solution onto a reliable domain is provided. This is achieved by a two-step iterative scheme. A sensitivity analysis identifies a critical situation. The latter leads to an adapted reliable safety domain. This new area is used to define a reliable design through a Newton-like process. Corresponding safety margins can be easily interpreted as partial safety factors. Finally, numerical applications in engineering are discussed to show the efficiency and the interest of the proposed algorithm.

  15. Reliability-based design and load tolerance evaluation using stochastic response surface and probabilistic sensitivities

    Wang, Haoyu

    Uncertainty is inevitable in structural design. This research presents an efficient uncertainty analysis technique based on stochastic response surfaces (SRS). The focus is on calculating uncertainty propagation using fewer number of function evaluations. Due to sensitivity analysis, the gradient information of the performance is efficiently calculated and used in constructing SRS. Based on SRS, reliability-based design optimization (RBDO) is studied intensively in this research. Probability sensitivity analysis using the sampling technique is also proposed. Since the computational cost of RBDO increases significantly proportional to the increasing number of random variables, global sensitivity analysis is introduced to adaptively reduce unessential random variables. It has been shown that the global sensitivity indices can be calculated analytically because the SRS employs the Hermite polynomials as bases. Traditional structural design focuses on designing a reliable structure under well characterized random factors (dimensions, shape, material properties, etc). Variations of these parameters are relatively small and well characterized. However, everyday engineering life tends to use the existing structural part in a different applications instead of designing a completely new part. In this research, a reliability-based safety envelope concept for load tolerance is introduced. This shows the capacity of the current design as a future reference for design upgrade, maintenance and control. The safety envelope is applied to estimate the load tolerance of a structural part with respect to the reliability of fatigue life. Stochastic response surface is also applied on robust design in this research. It is shown that the polynomial chaos expansion with appropriate bases provides an accurate and efficient tool in evaluating the performance variance. In addition, the sensitivity of the output variance, which is critical in the mathematical programming method, is

  16. Reliability Evaluation for the Running State of the Manufacturing System Based on Poor Information

    Xintao Xia


    Full Text Available The output performance of the manufacturing system has a direct impact on the mechanical product quality. For guaranteeing product quality and production cost, many firms try to research the crucial issues on reliability of the manufacturing system with small sample data, to evaluate whether the manufacturing system is capable or not. The existing reliability methods depend on a known probability distribution or vast test data. However, the population performances of complex systems become uncertain as processing time; namely, their probability distributions are unknown, if the existing methods are still taken into account; it is ineffective. This paper proposes a novel evaluation method based on poor information to settle the problems of reliability of the running state of a manufacturing system under the condition of small sample sizes with a known or unknown probability distribution. Via grey bootstrap method, maximum entropy principle, and Poisson process, the experimental investigation on reliability evaluation for the running state of the manufacturing system shows that, under the best confidence level P=0.95, if the reliability degree of achieving running quality is r>0.65, the intersection area between the inspection data and the intrinsic data is A(T>0.3 and the variation probability of the inspection data is PB(T≤0.7, and the running state of the manufacturing system is reliable; otherwise, it is not reliable. And the sensitivity analysis regarding the size of the samples can show that the size of the samples has no effect on the evaluation results obtained by the evaluation method. The evaluation method proposed provides the scientific decision and suggestion for judging the running state of the manufacturing system reasonably, which is efficient, profitable, and organized.

  17. Effect of wine dilution on the reliability of tannin analysis by protein precipitation

    Jensen, Jacob Skibsted; Werge, Hans Henrik Malmborg; Egebo, Max


    A reported analytical method for tannin quantification relies on selective precipitation of tannins with bovine serum albumin. The reliability of tannin analysis by protein precipitation on wines having variable tannin levels was evaluated by measuring the tannin concentration of various dilutions...... of five commercial red wines. Tannin concentrations of both very diluted and concentrated samples were systematically underestimated, which could be explained by a precipitation threshold and insufficient protein for precipitation, respectively. Based on these findings, we have defined a valid range...

  18. Reliability Information Analysis Center 1st Quarter 2007, Technical Area Task (TAT) Report


    07 planning conference 14 Dec 06 II Marine Expeditionary Force (MEF) meeting with Major Smith 14 Dec 06 Gulf of Mexico Tyndall Air Force Base Missile...Restructured action item spreadsheet " Reviewed the following storyboards (functional flow, graphics and text): 1. 050101 Main Rotor System components 2... storyboards (functional flow, graphics, and text): o 050101 Main Rotor System components. Reliability Information Analysis Center 6000 Flanagan Road

  19. A damage mechanics based approach to structural deterioration and reliability

    Bhattcharya, B.; Ellingwood, B. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering


    Structural deterioration often occurs without perceptible manifestation. Continuum damage mechanics defines structural damage in terms of the material microstructure, and relates the damage variable to the macroscopic strength or stiffness of the structure. This enables one to predict the state of damage prior to the initiation of a macroscopic flaw, and allows one to estimate residual strength/service life of an existing structure. The accumulation of damage is a dissipative process that is governed by the laws of thermodynamics. Partial differential equations for damage growth in terms of the Helmholtz free energy are derived from fundamental thermodynamical conditions. Closed-form solutions to the equations are obtained under uniaxial loading for ductile deformation damage as a function of plastic strain, for creep damage as a function of time, and for fatigue damage as function of number of cycles. The proposed damage growth model is extended into the stochastic domain by considering fluctuations in the free energy, and closed-form solutions of the resulting stochastic differential equation are obtained in each of the three cases mentioned above. A reliability analysis of a ring-stiffened cylindrical steel shell subjected to corrosion, accidental pressure, and temperature is performed.

  20. Probabilistic durability assessment of concrete structures in marine environments: Reliability and sensitivity analysis

    Yu, Bo; Ning, Chao-lie; Li, Bing


    A probabilistic framework for durability assessment of concrete structures in marine environments was proposed in terms of reliability and sensitivity analysis, which takes into account the uncertainties under the environmental, material, structural and executional conditions. A time-dependent probabilistic model of chloride ingress was established first to consider the variations in various governing parameters, such as the chloride concentration, chloride diffusion coefficient, and age factor. Then the Nataf transformation was adopted to transform the non-normal random variables from the original physical space into the independent standard Normal space. After that the durability limit state function and its gradient vector with respect to the original physical parameters were derived analytically, based on which the first-order reliability method was adopted to analyze the time-dependent reliability and parametric sensitivity of concrete structures in marine environments. The accuracy of the proposed method was verified by comparing with the second-order reliability method and the Monte Carlo simulation. Finally, the influences of environmental conditions, material properties, structural parameters and execution conditions on the time-dependent reliability of concrete structures in marine environments were also investigated. The proposed probabilistic framework can be implemented in the decision-making algorithm for the maintenance and repair of deteriorating concrete structures in marine environments.