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Sample records for reliability prediction assessment

  1. Application of structural reliability and risk assessment to life prediction and life extension decision making

    International Nuclear Information System (INIS)

    Meyer, T.A.; Balkey, K.R.; Bishop, B.A.

    1987-01-01

    There can be numerous uncertainties involved in performing component life assessments. In addition, sufficient data may be unavailable to make a useful life prediction. Structural Reliability and Risk Assessment (SRRA) is primarily an analytical methodology or tool that quantifies the impact of uncertainties on the structural life of plant components and can address the lack of data in component life prediction. As a prelude to discussing the technical aspects of SRRA, a brief review of general component life prediction methods is first made so as to better develop an understanding of the role of SRRA in such evaluations. SRRA is then presented as it is applied in component life evaluations with example applications being discussed for both nuclear and non-nuclear components

  2. Dynamic reliability assessment and prediction for repairable systems with interval-censored data

    International Nuclear Information System (INIS)

    Peng, Yizhen; Wang, Yu; Zi, YanYang; Tsui, Kwok-Leung; Zhang, Chuhua

    2017-01-01

    The ‘Test, Analyze and Fix’ process is widely applied to improve the reliability of a repairable system. In this process, dynamic reliability assessment for the system has been paid a great deal of attention. Due to instrument malfunctions, staff omissions and imperfect inspection strategies, field reliability data are often subject to interval censoring, making dynamic reliability assessment become a difficult task. Most traditional methods assume this kind of data as multiple normal distributed variables or the missing mechanism as missing at random, which may cause a large bias in parameter estimation. This paper proposes a novel method to evaluate and predict the dynamic reliability of a repairable system subject to interval-censored problem. First, a multiple imputation strategy based on the assumption that the reliability growth trend follows a nonhomogeneous Poisson process is developed to derive the distributions of missing data. Second, a new order statistic model that can transfer the dependent variables into independent variables is developed to simplify the imputation procedure. The unknown parameters of the model are iteratively inferred by the Monte Carlo expectation maximization (MCEM) algorithm. Finally, to verify the effectiveness of the proposed method, a simulation and a real case study for gas pipeline compressor system are implemented. - Highlights: • A new multiple imputation strategy was developed to derive the PDF of missing data. • A new order statistic model was developed to simplify the imputation procedure. • The parameters of the order statistic model were iteratively inferred by MCEM. • A real cases study was conducted to verify the effectiveness of the proposed method.

  3. Remaining life prediction of I and C cables for reliability assessment of NPP systems

    International Nuclear Information System (INIS)

    Santhosh, T.V.; Ghosh, A.K.; Fernandes, B.G.

    2012-01-01

    Highlights: ► A framework for time dependent reliability prediction of I and C cables for use in PSA of NPP has been developed using stress–strength interference theory. ► The proposed methodology has been illustrated with the accelerated thermal aging data on a typical XLPE cable. ► The behavior of insulation resistance when the degradation process is linear or exponential has also been modeled. ► The reliability index or probability of failure obtained from this approach can be used in system reliability evaluation to account for cable aging for PSA of NPP. - Abstract: Instrumentation and control (I and C) cables are one of the most important components in nuclear power plants (NPPs) because they provide power to safety-related equipment and also to transmit signals to and from various controllers to perform safety operations. I and C cables in NPP are subjected to a variety of aging and degradation stressors that can produce immediate degradation or aging-related mechanisms causing the degradation of cable components over time. Although, there exits several life estimation techniques, currently there is no any standard methodology or an approach toward estimating the time dependent reliability of I and C cables that can be directly used in probabilistic safety assessment (PSA) applications. Hence, the objective of this study is to develop an approach to estimate and confirm the continued acceptable margin in cable insulation life over time subjected to aging. This paper presents a framework based on the structural reliability theory to quantify the life time of I and C cable subjecting to thermal aging. Since cross-linked polyethylene (XLPE) cables are extensively being used in Indian NPPs, the remaining life time evaluations have been carried out for a typical XLPE cable. However, the methodology can be extended to other cables such as polyvinyl chloride (PVC), ethylene propylene rubber (EPR), etc.

  4. Human Reliability Assessments: Using the Past (Shuttle) to Predict the Future (Orion)

    Science.gov (United States)

    DeMott, Diana L.; Bigler, Mark A.

    2017-01-01

    NASA (National Aeronautics and Space Administration) Johnson Space Center (JSC) Safety and Mission Assurance (S&MA) uses two human reliability analysis (HRA) methodologies. The first is a simplified method which is based on how much time is available to complete the action, with consideration included for environmental and personal factors that could influence the human's reliability. This method is expected to provide a conservative value or placeholder as a preliminary estimate. This preliminary estimate or screening value is used to determine which placeholder needs a more detailed assessment. The second methodology is used to develop a more detailed human reliability assessment on the performance of critical human actions. This assessment needs to consider more than the time available, this would include factors such as: the importance of the action, the context, environmental factors, potential human stresses, previous experience, training, physical design interfaces, available procedures/checklists and internal human stresses. The more detailed assessment is expected to be more realistic than that based primarily on time available. When performing an HRA on a system or process that has an operational history, we have information specific to the task based on this history and experience. In the case of a Probabilistic Risk Assessment (PRA) that is based on a new design and has no operational history, providing a "reasonable" assessment of potential crew actions becomes more challenging. To determine what is expected of future operational parameters, the experience from individuals who had relevant experience and were familiar with the system and process previously implemented by NASA was used to provide the "best" available data. Personnel from Flight Operations, Flight Directors, Launch Test Directors, Control Room Console Operators, and Astronauts were all interviewed to provide a comprehensive picture of previous NASA operations. Verification of the

  5. The reliability, validity, sensitivity, specificity and predictive values of the Chinese version of the Rowland Universal Dementia Assessment Scale.

    Science.gov (United States)

    Chen, Chia-Wei; Chu, Hsin; Tsai, Chia-Fen; Yang, Hui-Ling; Tsai, Jui-Chen; Chung, Min-Huey; Liao, Yuan-Mei; Chi, Mei-Ju; Chou, Kuei-Ru

    2015-11-01

    The purpose of this study was to translate the Rowland Universal Dementia Assessment Scale into Chinese and to evaluate the psychometric properties (reliability and validity) and the diagnostic properties (sensitivity, specificity and predictive values) of the Chinese version of the Rowland Universal Dementia Assessment Scale. The accurate detection of early dementia requires screening tools with favourable cross-cultural linguistic and appropriate sensitivity, specificity, and predictive values, particularly for Chinese-speaking populations. This was a cross-sectional, descriptive study. Overall, 130 participants suspected to have cognitive impairment were enrolled in the study. A test-retest for determining reliability was scheduled four weeks after the initial test. Content validity was determined by five experts, whereas construct validity was established by using contrasted group technique. The participants' clinical diagnoses were used as the standard in calculating the sensitivity, specificity, positive predictive value and negative predictive value. The study revealed that the Chinese version of the Rowland Universal Dementia Assessment Scale exhibited a test-retest reliability of 0.90, an internal consistency reliability of 0.71, an inter-rater reliability (kappa value) of 0.88 and a content validity index of 0.97. Both the patients and healthy contrast group exhibited significant differences in their cognitive ability. The optimal cut-off points for the Chinese version of the Rowland Universal Dementia Assessment Scale in the test for mild cognitive impairment and dementia were 24 and 22, respectively; moreover, for these two conditions, the sensitivities of the scale were 0.79 and 0.76, the specificities were 0.91 and 0.81, the areas under the curve were 0.85 and 0.78, the positive predictive values were 0.99 and 0.83 and the negative predictive values were 0.96 and 0.91 respectively. The Chinese version of the Rowland Universal Dementia Assessment Scale

  6. Assessing the reliability of predictive activity coefficient models for molecules consisting of several functional groups

    Directory of Open Access Journals (Sweden)

    R. P. Gerber

    2013-03-01

    Full Text Available Currently, the most successful predictive models for activity coefficients are those based on functional groups such as UNIFAC. In contrast, these models require a large amount of experimental data for the determination of their parameter matrix. A more recent alternative is the models based on COSMO, for which only a small set of universal parameters must be calibrated. In this work, a recalibrated COSMO-SAC model was compared with the UNIFAC (Do model employing experimental infinite dilution activity coefficient data for 2236 non-hydrogen-bonding binary mixtures at different temperatures. As expected, UNIFAC (Do presented better overall performance, with a mean absolute error of 0.12 ln-units against 0.22 for our COSMO-SAC implementation. However, in cases involving molecules with several functional groups or when functional groups appear in an unusual way, the deviation for UNIFAC was 0.44 as opposed to 0.20 for COSMO-SAC. These results show that COSMO-SAC provides more reliable predictions for multi-functional or more complex molecules, reaffirming its future prospects.

  7. Predictive Reliability Assessment of the Automatic Clutch on a Primary Sodium Pump Drive

    International Nuclear Information System (INIS)

    Westwell, P.

    1975-01-01

    This paper examines the reliability of a group of three clutch couplings each mounted between a pony motor and the main drive for the primary sodium pumps. The sodium pumps specification requires that continuously running AC pony motors be fitted to give a guaranteed 10% drive to the pumps in the event of a main supply failure. The drive to the main shaft is via 3 : 1 reduction gearing such that a six pole pony motor running at 300 rpm would drive the main shaft at 100 rpm i.e., 10% of its rated speed. In order that the pony motor drive could be permanently energised during normal operation a free wheeling clutch is fitted between the motor and the reduction gearing. The type of clutch chosen is. the Synchro-Self Shifting (SSS) clutch, shown in Figure 1. This type of clutch has proved itself under fairly onerous operating conditions, but is normally mounted on a horizontal driving shaft whereas in this case because of space limitations, it is necessary to mount it vertically. The reliability target set is that the chance of losing all three independent back-up pony motor drives on loss of main supplies should fall within the 10 -5 - 10 -6 band. Since the electrical supplies and other parts of the pony motor drives have been assessed within this target and some doubts expressed about the clutch it was now necessary to look at this in some detail

  8. Is epicardial adipose tissue, assessed by echocardiography, a reliable method for visceral adipose tissue prediction?

    Science.gov (United States)

    Silaghi, Alina Cristina; Poantă, Laura; Valea, Ana; Pais, Raluca; Silaghi, Horatiu

    2011-03-01

    Epicardial adipose tissue is an ectopic fat storage at the heart surface in direct contact with the coronary arteries. It is considered a metabolically active tissue, being a local source of pro-inflammatory factors that contribute to the pathogenesis of coronary artery disease. The AIM of our study was to establish correlations between echocardiographic assessment of epicardial adipose tissue and anthropometric and ultrasound measurements of the central and peripheral fat depots. The study was conducted on 22 patients with or without coronaropathy. Epicardial adipose tissue was measured using Aloka Prosound α 10 machine with a 3.5-7.5 MHz variable-frequency transducer and subcutaneous and visceral fat with Esaote Megas GPX machine and 3.5-7.5 MHz variable frequency transducer. Epicardial adipose tissue measured by echocardiography is correlated with waist circumference (p < 0.05), visceral adipose tissue thickness measured by ultrasonography (US) and is not correlated with body mass index (p = 0.315), hip and thigh circumference or subcutaneous fat thickness measured by US. Our study confirms that US assessment of epicardial fat correlates with anthropometric and US measurements of the central fat, representing an indirect but reliable marker of the visceral fat.

  9. Interactive reliability assessment using an integrated reliability data bank

    International Nuclear Information System (INIS)

    Allan, R.N.; Whitehead, A.M.

    1986-01-01

    The logical structure, techniques and practical application of a computer-aided technique based on a microcomputer using floppy disc Random Access Files is described. This interactive computational technique is efficient if the reliability prediction program is coupled directly to a relevant source of data to create an integrated reliability assessment/reliability data bank system. (DG)

  10. Approach to reliability assessment

    International Nuclear Information System (INIS)

    Green, A.E.; Bourne, A.J.

    1975-01-01

    Experience has shown that reliability assessments can play an important role in the early design and subsequent operation of technological systems where reliability is at a premium. The approaches to and techniques for such assessments, which have been outlined in the paper, have been successfully applied in variety of applications ranging from individual equipments to large and complex systems. The general approach involves the logical and systematic establishment of the purpose, performance requirements and reliability criteria of systems. This is followed by an appraisal of likely system achievment based on the understanding of different types of variational behavior. A fundamental reliability model emerges from the correlation between the appropriate Q and H functions for performance requirement and achievement. This model may cover the complete spectrum of performance behavior in all the system dimensions

  11. New Approaches to Reliability Assessment

    DEFF Research Database (Denmark)

    Ma, Ke; Wang, Huai; Blaabjerg, Frede

    2016-01-01

    of energy. New approaches for reliability assessment are being taken in the design phase of power electronics systems based on the physics-of-failure in components. In this approach, many new methods, such as multidisciplinary simulation tools, strength testing of components, translation of mission profiles......, and statistical analysis, are involved to enable better prediction and design of reliability for products. This article gives an overview of the new design flow in the reliability engineering of power electronics from the system-level point of view and discusses some of the emerging needs for the technology...

  12. Nonparametric predictive inference in reliability

    International Nuclear Information System (INIS)

    Coolen, F.P.A.; Coolen-Schrijner, P.; Yan, K.J.

    2002-01-01

    We introduce a recently developed statistical approach, called nonparametric predictive inference (NPI), to reliability. Bounds for the survival function for a future observation are presented. We illustrate how NPI can deal with right-censored data, and discuss aspects of competing risks. We present possible applications of NPI for Bernoulli data, and we briefly outline applications of NPI for replacement decisions. The emphasis is on introduction and illustration of NPI in reliability contexts, detailed mathematical justifications are presented elsewhere

  13. Prediction of Osteoporosis through Radiographic Assessment of Proximal Femoral Morphology and Texture in Elderly; is it Valid and Reliable

    Directory of Open Access Journals (Sweden)

    Özkan Köse

    2015-08-01

    Full Text Available Objective: The purpose of this study was to determine the best predictive radiographic measurement method to identify the presence of osteoporosis and test the inter-observer and intra-observer reliability and validity of these methods in postmenopausal women. Materials and Methods: Ninety-two elderly female patients who presented with hip pain were included. Hip radiographs were used to determine the values of Singh index (SI, canal-to-calcar ratio (CCR, and cortical thickness index (CTI. All measurements were performed by two independent observers on two separate occasions, at least 4 weeks apart. Bone mineral density (BMD was assessed by DEXA. In the first part of the analysis, reliability of the all measurement methods was tested. In the second part, correlation coefficient (Pearson r was used to determine the relationship between the measurement methods and BMD. Finally ROC curve analysis was performed to determine the sensitivity, specificity, and threshold values for each radiographic measurement method. Results: Intra-observer reliability analysis of SI revealed kappa coefficient of 0.359 for observer A, and 0.224 for observer B. Inter-observer reliability analysis of SI revealed kappa coefficient of 0.070 for observer A and 0.051 for observer B. The intra-observer and inter-observer reliability was good and excellent for CTI and CCR for both observers (ICC: 0.920 and ICC: 0.936. There was no correlation between SI and BMD (p=0.818. On the other hand, there was a significant correlation between CTI and CCR and BMD (p=0.001. All measured indices were significantly different (p<0.05 between osteoporotic and non-osteoporotic patients. CTI value less than 0.3 or CCR value less than 0.47 reflects the presence of osteoporosis with 100% sensitivity and 98% specificity. Conclusion: SI is not reliable and do not correlate with BMD. However, both CTI and CCR showed good and excellent reliability, and each index correlated well with the real BMD

  14. Assessing the reliability, predictive and construct validity of historical, clinical and risk management-20 (HCR-20) in Mexican psychiatric inpatients.

    Science.gov (United States)

    Sada, Andrea; Robles-García, Rebeca; Martínez-López, Nicolás; Hernández-Ramírez, Rafael; Tovilla-Zarate, Carlos-Alfonso; López-Munguía, Fernando; Suárez-Alvarez, Enrique; Ayala, Xochitl; Fresán, Ana

    2016-08-01

    Assessing dangerousness to gauge the likelihood of future violent behaviour has become an integral part of clinical mental health practice in forensic and non-forensic psychiatric settings, one of the most effective instruments for this being the Historical, Clinical and Risk Management-20 (HCR-20). To examine the HCR-20 factor structure in Mexican psychiatric inpatients and to obtain its predictive validity and reliability for use in this population. In total, 225 patients diagnosed with psychotic, affective or personality disorders were included. The HCR-20 was applied at hospital admission and violent behaviours were assessed during psychiatric hospitalization using the Overt Aggression Scale (OAS). Construct validity, predictive validity and internal consistency were determined. Violent behaviour remains more severe in patients classified in the high-risk group during hospitalization. Fifteen items displayed adequate communalities in the original designated domains of the HCR-20 and internal consistency of the instruments was high. The HCR-20 is a suitable instrument for predicting violence risk in Mexican psychiatric inpatients.

  15. Safety and reliability assessment

    International Nuclear Information System (INIS)

    1979-01-01

    This report contains the papers delivered at the course on safety and reliability assessment held at the CSIR Conference Centre, Scientia, Pretoria. The following topics were discussed: safety standards; licensing; biological effects of radiation; what is a PWR; safety principles in the design of a nuclear reactor; radio-release analysis; quality assurance; the staffing, organisation and training for a nuclear power plant project; event trees, fault trees and probability; Automatic Protective Systems; sources of failure-rate data; interpretation of failure data; synthesis and reliability; quantification of human error in man-machine systems; dispersion of noxious substances through the atmosphere; criticality aspects of enrichment and recovery plants; and risk and hazard analysis. Extensive examples are given as well as case studies

  16. OSS reliability measurement and assessment

    CERN Document Server

    Yamada, Shigeru

    2016-01-01

    This book analyses quantitative open source software (OSS) reliability assessment and its applications, focusing on three major topic areas: the Fundamentals of OSS Quality/Reliability Measurement and Assessment; the Practical Applications of OSS Reliability Modelling; and Recent Developments in OSS Reliability Modelling. Offering an ideal reference guide for graduate students and researchers in reliability for open source software (OSS) and modelling, the book introduces several methods of reliability assessment for OSS including component-oriented reliability analysis based on analytic hierarchy process (AHP), analytic network process (ANP), and non-homogeneous Poisson process (NHPP) models, the stochastic differential equation models and hazard rate models. These measurement and management technologies are essential to producing and maintaining quality/reliable systems using OSS.

  17. Reliability Assessment Of Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2014-01-01

    Reduction of cost of energy for wind turbines are very important in order to make wind energy competitive compared to other energy sources. Therefore the turbine components should be designed to have sufficient reliability but also not be too costly (and safe). This paper presents models...... for uncertainty modeling and reliability assessment of especially the structural components such as tower, blades, substructure and foundation. But since the function of a wind turbine is highly dependent on many electrical and mechanical components as well as a control system also reliability aspects...... of these components are discussed and it is described how there reliability influences the reliability of the structural components. Two illustrative examples are presented considering uncertainty modeling, reliability assessment and calibration of partial safety factors for structural wind turbine components exposed...

  18. Software reliability assessment

    International Nuclear Information System (INIS)

    Barnes, M.; Bradley, P.A.; Brewer, M.A.

    1994-01-01

    The increased usage and sophistication of computers applied to real time safety-related systems in the United Kingdom has spurred on the desire to provide a standard framework within which to assess dependable computing systems. Recent accidents and ensuing legislation have acted as a catalyst in this area. One particular aspect of dependable computing systems is that of software, which is usually designed to reduce risk at the system level, but which can increase risk if it is unreliable. Various organizations have recognized the problem of assessing the risk imposed to the system by unreliable software, and have taken initial steps to develop and use such assessment frameworks. This paper relates the approach of Consultancy Services of AEA Technology in developing a framework to assess the risk imposed by unreliable software. In addition, the paper discusses the experiences gained by Consultancy Services in applying the assessment framework to commercial and research projects. The framework is applicable to software used in safety applications, including proprietary software. Although the paper is written with Nuclear Reactor Safety applications in mind, the principles discussed can be applied to safety applications in all industries

  19. Final report on reliability and lifetime prediction.

    Energy Technology Data Exchange (ETDEWEB)

    Gillen, Kenneth T; Wise, Jonathan; Jones, Gary D.; Causa, Al G.; Terrill, Edward R.; Borowczak, Marc

    2012-12-01

    This document highlights the important results obtained from the subtask of the Goodyear CRADA devoted to better understanding reliability of tires and to developing better lifetime prediction methods. The overall objective was to establish the chemical and physical basis for the degradation of tires using standard as well as unique models and experimental techniques. Of particular interest was the potential application of our unique modulus profiling apparatus for assessing tire properties and for following tire degradation. During the course of this complex investigation, extensive relevant information was generated, including experimental results, data analyses and development of models and instruments. Detailed descriptions of the findings are included in this report.

  20. Reliability tasks from prediction to field use

    International Nuclear Information System (INIS)

    Guyot, Christian.

    1975-01-01

    This tutorial paper is part of a series intended to sensitive on reliability prolems. Reliability probabilistic concept, is an important parameter of availability. Reliability prediction is an estimation process for evaluating design progress. It is only by the application of a reliability program that reliability objectives can be attained through the different stages of work: conception, fabrication, field use. The user is mainly interested in operational reliability. Indication are given on the support and the treatment of data in the case of electronic equipment at C.E.A. Reliability engineering requires a special state of mind which must be formed and developed in a company in the same way as it may be done for example for safety [fr

  1. Using image analysis as a tool for assessment of prognostic and predictive biomarkers for breast cancer: How reliable is it?

    Directory of Open Access Journals (Sweden)

    Mark C Lloyd

    2010-01-01

    Full Text Available Background : Estrogen receptor (ER, progesterone receptor (PR and human epidermal growth factor receptor-2 (HER2 are important and well-established prognostic and predictive biomarkers for breast cancers and routinely tested on patient′s tumor samples by immunohistochemical (IHC study. The accuracy of these test results has substantial impact on patient management. A critical factor that contributes to the result is the interpretation (scoring of IHC. This study investigates how computerized image analysis can play a role in a reliable scoring, and identifies potential pitfalls with common methods. Materials and Methods : Whole slide images of 33 invasive ductal carcinoma (IDC (10 ER and 23 HER2 were scored by pathologist under the light microscope and confirmed by another pathologist. The HER2 results were additionally confirmed by fluorescence in situ hybridization (FISH. The scoring criteria were adherent to the guidelines recommended by the American Society of Clinical Oncology/College of American Pathologists. Whole slide stains were then scored by commercially available image analysis algorithms from Definiens (Munich, Germany and Aperio Technologies (Vista, CA, USA. Each algorithm was modified specifically for each marker and tissue. The results were compared with the semi-quantitative manual scoring, which was considered the gold standard in this study. Results : For HER2 positive group, each algorithm scored 23/23 cases within the range established by the pathologist. For ER, both algorithms scored 10/10 cases within range. The performance of each algorithm varies somewhat from the percentage of staining as compared to the pathologist′s reading. Conclusions : Commercially available computerized image analysis can be useful in the evaluation of ER and HER2 IHC results. In order to achieve accurate results either manual pathologist region selection is necessary, or an automated region selection tool must be employed. Specificity can

  2. Single-leg lateral, horizontal, and vertical jump assessment: reliability, interrelationships, and ability to predict sprint and change-of-direction performance.

    Science.gov (United States)

    Meylan, Cesar; McMaster, Travis; Cronin, John; Mohammad, Nur Ikhwan; Rogers, Cailyn; Deklerk, Melissa

    2009-07-01

    The purposes of this study were to determine the reliability of unilateral vertical, horizontal, and lateral countermovement jump assessments, the interrelationship between these tests, and their usefulness as predictors of sprint (10 m) and change-of-direction (COD) performance for 80 men and women physical education students. Jump performance was assessed on a contact mat and sprint, and COD performances were assessed using timing lights. With regard to the reliability statistics, the largest coefficient of variation (CV) was observed for the vertical jump (CV = 6.7-7.2%) of both genders, whereas the sprint and COD assessments had smallest variability (CV = 0.8 to 2.8%). All intraclass correlation coefficients (ICC) were greater than 0.85, except for the men's COD assessment with the alternate leg. The shared variance between the single-leg vertical, horizontal, and lateral jumps for men and women was less than 50%, indicating that the jumps are relatively independent of one another and represent different leg strength/power qualities. The ability of the jumps to predict sprint and COD performance was limited (R2 < 43%). It would seem that the ability to change direction with 1 leg is relatively independent of a COD with the other leg, especially in the women (R < 30%) of this study. However, if 1 jump assessment were selected to predict sprint and COD performance in a test battery, the single-leg horizontal countermovement jump would seem the logical choice, given the results of this study. Many of the findings in this study have interesting diagnostic and training implications for the strength and conditioning coach.

  3. Reliability Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Middleton, C. R.

    This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the details of a methodology which can be used to generate Whole Life (WL) reliability...... profiles. These WL reliability profiles may be used to establish revised rules for concrete bridges. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

  4. Reliability assessment of Wind turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2015-01-01

    Wind turbines can be considered as structures that are in between civil engineering structures and machines since they consist of structural components and many electrical and machine components together with a control system. Further, a wind turbine is not a one-of-a-kind structure...... but manufactured in series production based on many component tests, some prototype tests and zeroseries wind turbines. These characteristics influence the reliability assessment where focus in this paper is on the structural components. Levelized Cost Of Energy is very important for wind energy, especially when...... comparing to other energy sources. Therefore much focus is on cost reductions and improved reliability both for offshore and onshore wind turbines. The wind turbine components should be designed to have sufficient reliability level with respect to both extreme and fatigue loads but also not be too costly...

  5. Human reliability assessment and probabilistic risk assessment

    International Nuclear Information System (INIS)

    Embrey, D.E.; Lucas, D.A.

    1989-01-01

    Human reliability assessment (HRA) is used within Probabilistic Risk Assessment (PRA) to identify the human errors (both omission and commission) which have a significant effect on the overall safety of the system and to quantify the probability of their occurrence. There exist a variey of HRA techniques and the selection of an appropriate one is often difficult. This paper reviews a number of available HRA techniques and discusses their strengths and weaknesses. The techniques reviewed include: decompositional methods, time-reliability curves and systematic expert judgement techniques. (orig.)

  6. Operator reliability assessment system (OPERAS)

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  7. Verification, validation, and reliability of predictions

    International Nuclear Information System (INIS)

    Pigford, T.H.; Chambre, P.L.

    1987-04-01

    The objective of predicting long-term performance should be to make reliable determinations of whether the prediction falls within the criteria for acceptable performance. Establishing reliable predictions of long-term performance of a waste repository requires emphasis on valid theories to predict performance. The validation process must establish the validity of the theory, the parameters used in applying the theory, the arithmetic of calculations, and the interpretation of results; but validation of such performance predictions is not possible unless there are clear criteria for acceptable performance. Validation programs should emphasize identification of the substantive issues of prediction that need to be resolved. Examples relevant to waste package performance are predicting the life of waste containers and the time distribution of container failures, establishing the criteria for defining container failure, validating theories for time-dependent waste dissolution that depend on details of the repository environment, and determining the extent of congruent dissolution of radionuclides in the UO 2 matrix of spent fuel. Prediction and validation should go hand in hand and should be done and reviewed frequently, as essential tools for the programs to design and develop repositories. 29 refs

  8. Automated reliability assessment for spectroscopic redshift measurements

    Science.gov (United States)

    Jamal, S.; Le Brun, V.; Le Fèvre, O.; Vibert, D.; Schmitt, A.; Surace, C.; Copin, Y.; Garilli, B.; Moresco, M.; Pozzetti, L.

    2018-03-01

    Context. Future large-scale surveys, such as the ESA Euclid mission, will produce a large set of galaxy redshifts (≥106) that will require fully automated data-processing pipelines to analyze the data, extract crucial information and ensure that all requirements are met. A fundamental element in these pipelines is to associate to each galaxy redshift measurement a quality, or reliability, estimate. Aim. In this work, we introduce a new approach to automate the spectroscopic redshift reliability assessment based on machine learning (ML) and characteristics of the redshift probability density function. Methods: We propose to rephrase the spectroscopic redshift estimation into a Bayesian framework, in order to incorporate all sources of information and uncertainties related to the redshift estimation process and produce a redshift posterior probability density function (PDF). To automate the assessment of a reliability flag, we exploit key features in the redshift posterior PDF and machine learning algorithms. Results: As a working example, public data from the VIMOS VLT Deep Survey is exploited to present and test this new methodology. We first tried to reproduce the existing reliability flags using supervised classification in order to describe different types of redshift PDFs, but due to the subjective definition of these flags (classification accuracy 58%), we soon opted for a new homogeneous partitioning of the data into distinct clusters via unsupervised classification. After assessing the accuracy of the new clusters via resubstitution and test predictions (classification accuracy 98%), we projected unlabeled data from preliminary mock simulations for the Euclid space mission into this mapping to predict their redshift reliability labels. Conclusions: Through the development of a methodology in which a system can build its own experience to assess the quality of a parameter, we are able to set a preliminary basis of an automated reliability assessment for

  9. Human reliability assessment in context

    International Nuclear Information System (INIS)

    Hollnagel, Erik

    2005-01-01

    Human Reliability Assessment (HRA) is conducted on the unspoken premise that 'human error' is a meaningful concept and that it can be associated with individual actions. The basis for this assumption it found in the origin of HRA, as a necessary extension of PSA to account for the impact of failures emanating from human actions. Although it was natural to model HRA on PSA, a large number of studies have shown that the premises are wrong, specifically that human and technological functions cannot be decomposed in the same manner. The general experience from accident studies also indicates that action failures are a function of the context, and that it is the variability of the context rather than the 'human error probability' that is the much sought for signal. Accepting this will have significant consequences for the way in which HRA, and ultimately also PSA, should be pursued

  10. Reliability and lifetime predictions of SLC klystrons

    International Nuclear Information System (INIS)

    Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Lee, T.G.; Vlieks, A.E.

    1989-01-01

    The energy upgrade of SLAC, with the first of the new 67 MW SLAC Linear Collider (SLC) klystrons, began over four years ago. Today there are over 200 of these klystrons in operation. As a result, there is a wealth of klystron performance and failure information that enables reasonable predictions to be made on life expectancy and reliability. Data from initial tests, follow-up tests and daily operation monitoring on the accelerator is stored for analysis. Presented here are life expectancy predictions with particular emphasis on cathode life. Also, based on this data, the authors will discuss some of the principal modes of failure. 3 refs., 2 figs., 1 tab

  11. Reliability and lifetime predictions of SLC klystrons

    International Nuclear Information System (INIS)

    Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Lee, T.G.; Vlieks, A.E.

    1989-03-01

    The energy upgrade of SLAC, with the first of the new 67 MW SLAC Linear Collider (SLC) klystrons, began over four years ago. Today there are over 200 of these klystrons in operation. As a result, there is a wealth klystron performance and failure information that enables reasonable predictions to be made on life expectancy and reliability. Data from initial tests, follow-up tests and daily operation monitoring on the accelerator is stores for analysis. Presented here are life expectancy predictions with particular emphasis on cathode life. Also, based on this data, we will discuss some of the principal modes of failure. 3 refs., 2 figs

  12. Prediction of Software Reliability using Bio Inspired Soft Computing Techniques.

    Science.gov (United States)

    Diwaker, Chander; Tomar, Pradeep; Poonia, Ramesh C; Singh, Vijander

    2018-04-10

    A lot of models have been made for predicting software reliability. The reliability models are restricted to using particular types of methodologies and restricted number of parameters. There are a number of techniques and methodologies that may be used for reliability prediction. There is need to focus on parameters consideration while estimating reliability. The reliability of a system may increase or decreases depending on the selection of different parameters used. Thus there is need to identify factors that heavily affecting the reliability of the system. In present days, reusability is mostly used in the various area of research. Reusability is the basis of Component-Based System (CBS). The cost, time and human skill can be saved using Component-Based Software Engineering (CBSE) concepts. CBSE metrics may be used to assess those techniques which are more suitable for estimating system reliability. Soft computing is used for small as well as large-scale problems where it is difficult to find accurate results due to uncertainty or randomness. Several possibilities are available to apply soft computing techniques in medicine related problems. Clinical science of medicine using fuzzy-logic, neural network methodology significantly while basic science of medicine using neural-networks-genetic algorithm most frequently and preferably. There is unavoidable interest shown by medical scientists to use the various soft computing methodologies in genetics, physiology, radiology, cardiology and neurology discipline. CBSE boost users to reuse the past and existing software for making new products to provide quality with a saving of time, memory space, and money. This paper focused on assessment of commonly used soft computing technique like Genetic Algorithm (GA), Neural-Network (NN), Fuzzy Logic, Support Vector Machine (SVM), Ant Colony Optimization (ACO), Particle Swarm Optimization (PSO), and Artificial Bee Colony (ABC). This paper presents working of soft computing

  13. Parts and Components Reliability Assessment: A Cost Effective Approach

    Science.gov (United States)

    Lee, Lydia

    2009-01-01

    System reliability assessment is a methodology which incorporates reliability analyses performed at parts and components level such as Reliability Prediction, Failure Modes and Effects Analysis (FMEA) and Fault Tree Analysis (FTA) to assess risks, perform design tradeoffs, and therefore, to ensure effective productivity and/or mission success. The system reliability is used to optimize the product design to accommodate today?s mandated budget, manpower, and schedule constraints. Stand ard based reliability assessment is an effective approach consisting of reliability predictions together with other reliability analyses for electronic, electrical, and electro-mechanical (EEE) complex parts and components of large systems based on failure rate estimates published by the United States (U.S.) military or commercial standards and handbooks. Many of these standards are globally accepted and recognized. The reliability assessment is especially useful during the initial stages when the system design is still in the development and hard failure data is not yet available or manufacturers are not contractually obliged by their customers to publish the reliability estimates/predictions for their parts and components. This paper presents a methodology to assess system reliability using parts and components reliability estimates to ensure effective productivity and/or mission success in an efficient manner, low cost, and tight schedule.

  14. Multivariate performance reliability prediction in real-time

    International Nuclear Information System (INIS)

    Lu, S.; Lu, H.; Kolarik, W.J.

    2001-01-01

    This paper presents a technique for predicting system performance reliability in real-time considering multiple failure modes. The technique includes on-line multivariate monitoring and forecasting of selected performance measures and conditional performance reliability estimates. The performance measures across time are treated as a multivariate time series. A state-space approach is used to model the multivariate time series. Recursive forecasting is performed by adopting Kalman filtering. The predicted mean vectors and covariance matrix of performance measures are used for the assessment of system survival/reliability with respect to the conditional performance reliability. The technique and modeling protocol discussed in this paper provide a means to forecast and evaluate the performance of an individual system in a dynamic environment in real-time. The paper also presents an example to demonstrate the technique

  15. Prediction of software operational reliability using testing environment factors

    International Nuclear Information System (INIS)

    Jung, Hoan Sung; Seong, Poong Hyun

    1995-01-01

    A number of software reliability models have been developed to estimate and to predict software reliability. However, there are no established standard models to quantify software reliability. Most models estimate the quality of software in reliability figures such as remaining faults, failure rate, or mean time to next failure at the testing phase, and they consider them ultimate indicators of software reliability. Experience shows that there is a large gap between predicted reliability during development and reliability measured during operation, which means that predicted reliability, or so-called test reliability, is not operational reliability. Customers prefer operational reliability to test reliability. In this study, we propose a method that predicts operational reliability rather than test reliability by introducing the testing environment factor that quantifies the changes in environments

  16. Predicting risk and human reliability: a new approach

    International Nuclear Information System (INIS)

    Duffey, R.; Ha, T.-S.

    2009-01-01

    Learning from experience describes human reliability and skill acquisition, and the resulting theory has been validated by comparison against millions of outcome data from multiple industries and technologies worldwide. The resulting predictions were used to benchmark the classic first generation human reliability methods adopted in probabilistic risk assessments. The learning rate, probabilities and response times are also consistent with the existing psychological models for human learning and error correction. The new approach also implies a finite lower bound probability that is not predicted by empirical statistical distributions that ignore the known and fundamental learning effects. (author)

  17. Reliability of windstorm predictions in the ECMWF ensemble prediction system

    Science.gov (United States)

    Becker, Nico; Ulbrich, Uwe

    2016-04-01

    Windstorms caused by extratropical cyclones are one of the most dangerous natural hazards in the European region. Therefore, reliable predictions of such storm events are needed. Case studies have shown that ensemble prediction systems (EPS) are able to provide useful information about windstorms between two and five days prior to the event. In this work, ensemble predictions with the European Centre for Medium-Range Weather Forecasts (ECMWF) EPS are evaluated in a four year period. Within the 50 ensemble members, which are initialized every 12 hours and are run for 10 days, windstorms are identified and tracked in time and space. By using a clustering approach, different predictions of the same storm are identified in the different ensemble members and compared to reanalysis data. The occurrence probability of the predicted storms is estimated by fitting a bivariate normal distribution to the storm track positions. Our results show, for example, that predicted storm clusters with occurrence probabilities of more than 50% have a matching observed storm in 80% of all cases at a lead time of two days. The predicted occurrence probabilities are reliable up to 3 days lead time. At longer lead times the occurrence probabilities are overestimated by the EPS.

  18. Software reliability prediction using SPN | Abbasabadee | Journal of ...

    African Journals Online (AJOL)

    Software reliability prediction using SPN. ... In this research for computation of software reliability, component reliability model based on SPN would be proposed. An isomorphic markov ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  19. Can shoulder dystocia be reliably predicted?

    Science.gov (United States)

    Dodd, Jodie M; Catcheside, Britt; Scheil, Wendy

    2012-06-01

    To evaluate factors reported to increase the risk of shoulder dystocia, and to evaluate their predictive value at a population level. The South Australian Pregnancy Outcome Unit's population database from 2005 to 2010 was accessed to determine the occurrence of shoulder dystocia in addition to reported risk factors, including age, parity, self-reported ethnicity, presence of diabetes and infant birth weight. Odds ratios (and 95% confidence interval) of shoulder dystocia was calculated for each risk factor, which were then incorporated into a logistic regression model. Test characteristics for each variable in predicting shoulder dystocia were calculated. As a proportion of all births, the reported rate of shoulder dystocia increased significantly from 0.95% in 2005 to 1.38% in 2010 (P = 0.0002). Using a logistic regression model, induction of labour and infant birth weight greater than both 4000 and 4500 g were identified as significant independent predictors of shoulder dystocia. The value of risk factors alone and when incorporated into the logistic regression model was poorly predictive of the occurrence of shoulder dystocia. While there are a number of factors associated with an increased risk of shoulder dystocia, none are of sufficient sensitivity or positive predictive value to allow their use clinically to reliably and accurately identify the occurrence of shoulder dystocia. © 2012 The Authors ANZJOG © 2012 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

  20. A method of predicting the reliability of CDM coil insulation

    International Nuclear Information System (INIS)

    Kytasty, A.; Ogle, C.; Arrendale, H.

    1992-01-01

    This paper presents a method of predicting the reliability of the Collider Dipole Magnet (CDM) coil insulation design. The method proposes a probabilistic treatment of electrical test data, stress analysis, material properties variability and loading uncertainties to give the reliability estimate. The approach taken to predict reliability of design related failure modes of the CDM is to form analytical models of the various possible failure modes and their related mechanisms or causes, and then statistically assess the contributions of the various contributing variables. The probability of the failure mode occurring is interpreted as the number of times one would expect certain extreme situations to combine and randomly occur. One of the more complex failure modes of the CDM will be used to illustrate this methodology

  1. Structural reliability assessment capability in NESSUS

    Science.gov (United States)

    Millwater, H.; Wu, Y.-T.

    1992-07-01

    The principal capabilities of NESSUS (Numerical Evaluation of Stochastic Structures Under Stress), an advanced computer code developed for probabilistic structural response analysis, are reviewed, and its structural reliability assessed. The code combines flexible structural modeling tools with advanced probabilistic algorithms in order to compute probabilistic structural response and resistance, component reliability and risk, and system reliability and risk. An illustrative numerical example is presented.

  2. Reliability assessments in qualitative health promotion research.

    Science.gov (United States)

    Cook, Kay E

    2012-03-01

    This article contributes to the debate about the use of reliability assessments in qualitative research in general, and health promotion research in particular. In this article, I examine the use of reliability assessments in qualitative health promotion research in response to health promotion researchers' commonly held misconception that reliability assessments improve the rigor of qualitative research. All qualitative articles published in the journal Health Promotion International from 2003 to 2009 employing reliability assessments were examined. In total, 31.3% (20/64) articles employed some form of reliability assessment. The use of reliability assessments increased over the study period, ranging from qualitative articles decreased. The articles were then classified into four types of reliability assessments, including the verification of thematic codes, the use of inter-rater reliability statistics, congruence in team coding and congruence in coding across sites. The merits of each type were discussed, with the subsequent discussion focusing on the deductive nature of reliable thematic coding, the limited depth of immediately verifiable data and the usefulness of such studies to health promotion and the advancement of the qualitative paradigm.

  3. Program integration of predictive maintenance with reliability centered maintenance

    International Nuclear Information System (INIS)

    Strong, D.K. Jr; Wray, D.M.

    1990-01-01

    This paper addresses improving the safety and reliability of power plants in a cost-effective manner by integrating the recently developed reliability centered maintenance techniques with the traditional predictive maintenance techniques of nuclear power plants. The topics of the paper include a description of reliability centered maintenance (RCM), enhancing RCM with predictive maintenance, predictive maintenance programs, condition monitoring techniques, performance test techniques, the mid-Atlantic Reliability Centered Maintenance Users Group, test guides and the benefits of shared guide development

  4. Evaluating the reliability of predictions made using environmental transfer models

    International Nuclear Information System (INIS)

    1989-01-01

    The development and application of mathematical models for predicting the consequences of releases of radionuclides into the environment from normal operations in the nuclear fuel cycle and in hypothetical accident conditions has increased dramatically in the last two decades. This Safety Practice publication has been prepared to provide guidance on the available methods for evaluating the reliability of environmental transfer model predictions. It provides a practical introduction of the subject and a particular emphasis has been given to worked examples in the text. It is intended to supplement existing IAEA publications on environmental assessment methodology. 60 refs, 17 figs, 12 tabs

  5. Operator reliability assessment system (OPERAS)

    International Nuclear Information System (INIS)

    Spurgin, A.J.; Hallam, J.W.; Spurgin, J.P.; Singh, A.

    1991-01-01

    The paper gives an overview of the OPERAS project. It discusses the background which led to the design of the PC-based data collection and analysis system connected to plant training simulators including those used for nuclear power plants. The usefulness of a system like OPERAS was perceived during an earlier EPRI project, the Operator Reliability Experiments project, by EPRI and PG and E. The data collection and analysis approaches used in OPERAS were developed during the ORE project. The paper not only discusses the design of OPERAS but discusses the functions performed and the current experiences with the two prototype systems. Also listed are potential uses of OPERAS by utility personnel in Operations, Training and PRA groups

  6. System reliability prediction using data from non-identical environments

    International Nuclear Information System (INIS)

    Bergman, B.; Ringi, M.

    1997-01-01

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

  7. Reevaluating Interrater Reliability in Offender Risk Assessment

    NARCIS (Netherlands)

    van der Knaap, L.M.; Leenarts, L.E.W.; Born, M.P.; Oosterveld, P.

    2012-01-01

    Offender risk and needs assessment, one of the pillars of the risk-need-responsivity model of offender rehabilitation, usually depends on raters assessing offender risk and needs. The few available studies of interrater reliability in offender risk assessment are, however, limited in the

  8. Reevaluating Interrater Reliability in Offender Risk Assessment

    Science.gov (United States)

    van der Knaap, Leontien M.; Leenarts, Laura E. W.; Born, Marise Ph.; Oosterveld, Paul

    2012-01-01

    Offender risk and needs assessment, one of the pillars of the risk-need-responsivity model of offender rehabilitation, usually depends on raters assessing offender risk and needs. The few available studies of interrater reliability in offender risk assessment are, however, limited in the generalizability of their results. The present study…

  9. Test-Retest Reliability and Predictive Validity of the Implicit Association Test in Children

    Science.gov (United States)

    Rae, James R.; Olson, Kristina R.

    2018-01-01

    The Implicit Association Test (IAT) is increasingly used in developmental research despite minimal evidence of whether children's IAT scores are reliable across time or predictive of behavior. When test-retest reliability and predictive validity have been assessed, the results have been mixed, and because these studies have differed on many…

  10. Prediction of software operational reliability using testing environment factors

    International Nuclear Information System (INIS)

    Jung, Hoan Sung; Seong, Poong Hyun

    1995-01-01

    For many years, many researches have focused on the quantification of software reliability and there are many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. The experiences show that the operational reliability is higher than the test reliability User's interest is on the operational reliability rather than on the test reliability, however. With the assumption that the difference in reliability results from the change of environment, testing environment factors comprising the aging factor and the coverage factor are defined in this study to predict the ultimate operational reliability with the failure data. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results are close to the actual data

  11. An approach for assessing human decision reliability

    International Nuclear Information System (INIS)

    Pyy, P.

    2000-01-01

    This paper presents a method to study human reliability in decision situations related to nuclear power plant disturbances. Decisions often play a significant role in handling of emergency situations. The method may be applied to probabilistic safety assessments (PSAs) in cases where decision making is an important dimension of an accident sequence. Such situations are frequent e.g. in accident management. In this paper, a modelling approach for decision reliability studies is first proposed. Then, a case study with two decision situations with relatively different characteristics is presented. Qualitative and quantitative findings of the study are discussed. In very simple decision cases with time pressure, time reliability correlation proved out to be a feasible reliability modelling method. In all other decision situations, more advanced probabilistic decision models have to be used. Finally, decision probability assessment by using simulator run results and expert judgement is presented

  12. Assessing reliability in energy supply systems

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  13. Reliability assessment based on subjective inferences

    International Nuclear Information System (INIS)

    Ma Zhibo; Zhu Jianshi; Xu Naixin

    2003-01-01

    The reliability information which comes from subjective analysis is often incomplete prior. This information can be generally assumed to exist in the form of either a stated prior mean of R (reliability) or a stated prior credibility interval on R. An efficient approach is developed to determine a complete beta prior distribution from the subjective information according to the principle of maximum entropy, and the the reliability of survival/failure product is assessed via Bayes theorem. Numerical examples are presented to illustrate the methods

  14. The Reliability and Predictive Validity of the Stalking Risk Profile.

    Science.gov (United States)

    McEwan, Troy E; Shea, Daniel E; Daffern, Michael; MacKenzie, Rachel D; Ogloff, James R P; Mullen, Paul E

    2018-03-01

    This study assessed the reliability and validity of the Stalking Risk Profile (SRP), a structured measure for assessing stalking risks. The SRP was administered at the point of assessment or retrospectively from file review for 241 adult stalkers (91% male) referred to a community-based forensic mental health service. Interrater reliability was high for stalker type, and moderate-to-substantial for risk judgments and domain scores. Evidence for predictive validity and discrimination between stalking recidivists and nonrecidivists for risk judgments depended on follow-up duration. Discrimination was moderate (area under the curve = 0.66-0.68) and positive and negative predictive values good over the full follow-up period ( Mdn = 170.43 weeks). At 6 months, discrimination was better than chance only for judgments related to stalking of new victims (area under the curve = 0.75); however, high-risk stalkers still reoffended against their original victim(s) 2 to 4 times as often as low-risk stalkers. Implications for the clinical utility and refinement of the SRP are discussed.

  15. Human reliability. Is probabilistic human reliability assessment possible?

    International Nuclear Information System (INIS)

    Mosneron Dupin, F.

    1996-01-01

    The possibility of carrying out Probabilistic Human Reliability Assessments (PHRA) is often doubted. Basing ourselves on the experience Electricite de France (EDF) has acquired in Probabilistic Safety Assessments for nuclear power plants, we show why the uncertainty of PHRA is very high. We then specify the limits of generic data and models for PHRA: very important factors are often poorly taken into account. To account for them, you need to have proper understanding of the actual context in which operators work. This demands surveys on the field (power plant and simulator) all of which must be carried out with behaviours science skills. The idea of estimating the probabilities of operator failure must not be abandoned, but probabilities must be given less importance, for they are only approximate indications. The qualitative aspects of PHRA should be given greater value (analysis process and qualitative insights). That is why the description (illustrated by case histories) of the main mechanisms of human behaviour, and of their manifestations in the nuclear power plant context (in terms of habits, attitudes, and informal methods and organization in particular) should be an important part of PHRA handbooks. These handbooks should also insist more on methods for gathering information on the actual context of the work of operators. Under these conditions, the PHRA should be possible and even desirable as a process for systematic analysis and assessment of human intervention. (author). 24 refs, 2 figs, 1 tab

  16. Human reliability. Is probabilistic human reliability assessment possible?

    Energy Technology Data Exchange (ETDEWEB)

    Mosneron Dupin, F

    1997-12-31

    The possibility of carrying out Probabilistic Human Reliability Assessments (PHRA) is often doubted. Basing ourselves on the experience Electricite de France (EDF) has acquired in Probabilistic Safety Assessments for nuclear power plants, we show why the uncertainty of PHRA is very high. We then specify the limits of generic data and models for PHRA: very important factors are often poorly taken into account. To account for them, you need to have proper understanding of the actual context in which operators work. This demands surveys on the field (power plant and simulator) all of which must be carried out with behaviours science skills. The idea of estimating the probabilities of operator failure must not be abandoned, but probabilities must be given less importance, for they are only approximate indications. The qualitative aspects of PHRA should be given greater value (analysis process and qualitative insights). That is why the description (illustrated by case histories) of the main mechanisms of human behaviour, and of their manifestations in the nuclear power plant context (in terms of habits, attitudes, and informal methods and organization in particular) should be an important part of PHRA handbooks. These handbooks should also insist more on methods for gathering information on the actual context of the work of operators. Under these conditions, the PHRA should be possible and even desirable as a process for systematic analysis and assessment of human intervention. (author). 24 refs, 2 figs, 1 tab.

  17. Prediction of safety critical software operational reliability from test reliability using testing environment factors

    International Nuclear Information System (INIS)

    Jung, Hoan Sung; Seong, Poong Hyun

    1999-01-01

    It has been a critical issue to predict the safety critical software reliability in nuclear engineering area. For many years, many researches have focused on the quantification of software reliability and there have been many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is however on the operational reliability rather than on the test reliability. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, from testing to operation, testing environment factors comprising the aging factor and the coverage factor are developed in this paper and used to predict the ultimate operational reliability with the failure data in testing phase. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results show that the proposed method can estimate the operational reliability accurately. (Author). 14 refs., 1 tab., 1 fig

  18. Reliable predictions of waste performance in a geologic repository

    International Nuclear Information System (INIS)

    Pigford, T.H.; Chambre, P.L.

    1985-08-01

    Establishing reliable estimates of long-term performance of a waste repository requires emphasis upon valid theories to predict performance. Predicting rates that radionuclides are released from waste packages cannot rest upon empirical extrapolations of laboratory leach data. Reliable predictions can be based on simple bounding theoretical models, such as solubility-limited bulk-flow, if the assumed parameters are reliably known or defensibly conservative. Wherever possible, performance analysis should proceed beyond simple bounding calculations to obtain more realistic - and usually more favorable - estimates of expected performance. Desire for greater realism must be balanced against increasing uncertainties in prediction and loss of reliability. Theoretical predictions of release rate based on mass-transfer analysis are bounding and the theory can be verified. Postulated repository analogues to simulate laboratory leach experiments introduce arbitrary and fictitious repository parameters and are shown not to agree with well-established theory. 34 refs., 3 figs., 2 tabs

  19. Conceptual Software Reliability Prediction Models for Nuclear Power Plant Safety Systems

    International Nuclear Information System (INIS)

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

    2000-01-01

    The objective of this project is to develop a method to predict the potential reliability of software to be used in a digital system instrumentation and control system. The reliability prediction is to make use of existing measures of software reliability such as those described in IEEE Std 982 and 982.2. This prediction must be of sufficient accuracy to provide a value for uncertainty that could be used in a nuclear power plant probabilistic risk assessment (PRA). For the purposes of the project, reliability was defined to be the probability that the digital system will successfully perform its intended safety function (for the distribution of conditions under which it is expected to respond) upon demand with no unintended functions that might affect system safety. The ultimate objective is to use the identified measures to develop a method for predicting the potential quantitative reliability of a digital system. The reliability prediction models proposed in this report are conceptual in nature. That is, possible prediction techniques are proposed and trial models are built, but in order to become a useful tool for predicting reliability, the models must be tested, modified according to the results, and validated. Using methods outlined by this project, models could be constructed to develop reliability estimates for elements of software systems. This would require careful review and refinement of the models, development of model parameters from actual experience data or expert elicitation, and careful validation. By combining these reliability estimates (generated from the validated models for the constituent parts) in structural software models, the reliability of the software system could then be predicted. Modeling digital system reliability will also require that methods be developed for combining reliability estimates for hardware and software. System structural models must also be developed in order to predict system reliability based upon the reliability

  20. Time-variant reliability assessment through equivalent stochastic process transformation

    International Nuclear Information System (INIS)

    Wang, Zequn; Chen, Wei

    2016-01-01

    Time-variant reliability measures the probability that an engineering system successfully performs intended functions over a certain period of time under various sources of uncertainty. In practice, it is computationally prohibitive to propagate uncertainty in time-variant reliability assessment based on expensive or complex numerical models. This paper presents an equivalent stochastic process transformation approach for cost-effective prediction of reliability deterioration over the life cycle of an engineering system. To reduce the high dimensionality, a time-independent reliability model is developed by translating random processes and time parameters into random parameters in order to equivalently cover all potential failures that may occur during the time interval of interest. With the time-independent reliability model, an instantaneous failure surface is attained by using a Kriging-based surrogate model to identify all potential failure events. To enhance the efficacy of failure surface identification, a maximum confidence enhancement method is utilized to update the Kriging model sequentially. Then, the time-variant reliability is approximated using Monte Carlo simulations of the Kriging model where system failures over a time interval are predicted by the instantaneous failure surface. The results of two case studies demonstrate that the proposed approach is able to accurately predict the time evolution of system reliability while requiring much less computational efforts compared with the existing analytical approach. - Highlights: • Developed a new approach for time-variant reliability analysis. • Proposed a novel stochastic process transformation procedure to reduce the dimensionality. • Employed Kriging models with confidence-based adaptive sampling scheme to enhance computational efficiency. • The approach is effective for handling random process in time-variant reliability analysis. • Two case studies are used to demonstrate the efficacy

  1. Assessment of the Reliability of Concrete Bridges

    DEFF Research Database (Denmark)

    Middleton, C. R.; Thoft-Christensen, Palle

    Although there has been a considerable amount of research into different aspects of concrete bridge reliability, it has still not been widely adopted in professional practice other than in the development and calibration of codes. This situation appears to be changing as there has been a signific......Although there has been a considerable amount of research into different aspects of concrete bridge reliability, it has still not been widely adopted in professional practice other than in the development and calibration of codes. This situation appears to be changing as there has been...... adopted to assist in achieving this goal. Rather than review the specific research on this subject this paper examines a number of key issues related to the practical application of reliability analysis to the assessment of concrete bridges....

  2. Scalable Joint Models for Reliable Uncertainty-Aware Event Prediction.

    Science.gov (United States)

    Soleimani, Hossein; Hensman, James; Saria, Suchi

    2017-08-21

    Missing data and noisy observations pose significant challenges for reliably predicting events from irregularly sampled multivariate time series (longitudinal) data. Imputation methods, which are typically used for completing the data prior to event prediction, lack a principled mechanism to account for the uncertainty due to missingness. Alternatively, state-of-the-art joint modeling techniques can be used for jointly modeling the longitudinal and event data and compute event probabilities conditioned on the longitudinal observations. These approaches, however, make strong parametric assumptions and do not easily scale to multivariate signals with many observations. Our proposed approach consists of several key innovations. First, we develop a flexible and scalable joint model based upon sparse multiple-output Gaussian processes. Unlike state-of-the-art joint models, the proposed model can explain highly challenging structure including non-Gaussian noise while scaling to large data. Second, we derive an optimal policy for predicting events using the distribution of the event occurrence estimated by the joint model. The derived policy trades-off the cost of a delayed detection versus incorrect assessments and abstains from making decisions when the estimated event probability does not satisfy the derived confidence criteria. Experiments on a large dataset show that the proposed framework significantly outperforms state-of-the-art techniques in event prediction.

  3. Reliability analysis and assessment of structural systems

    International Nuclear Information System (INIS)

    Yao, J.T.P.; Anderson, C.A.

    1977-01-01

    The study of structural reliability deals with the probability of having satisfactory performance of the structure under consideration within any specific time period. To pursue this study, it is necessary to apply available knowledge and methodology in structural analysis (including dynamics) and design, behavior of materials and structures, experimental mechanics, and the theory of probability and statistics. In addition, various severe loading phenomena such as strong motion earthquakes and wind storms are important considerations. For three decades now, much work has been done on reliability analysis of structures, and during this past decade, certain so-called 'Level I' reliability-based design codes have been proposed and are in various stages of implementation. These contributions will be critically reviewed and summarized in this paper. Because of the undesirable consequences resulting from the failure of nuclear structures, it is important and desirable to consider the structural reliability in the analysis and design of these structures. Moreover, after these nuclear structures are constructed, it is desirable for engineers to be able to assess the structural reliability periodically as well as immediately following the occurrence of severe loading conditions such as a strong-motion earthquake. During this past decade, increasing use has been made of techniques of system identification in structural engineering. On the basis of non-destructive test results, various methods have been developed to obtain an adequate mathematical model (such as the equations of motion with more realistic parameters) to represent the structural system

  4. Conformal prediction for reliable machine learning theory, adaptations and applications

    CERN Document Server

    Balasubramanian, Vineeth; Vovk, Vladimir

    2014-01-01

    The conformal predictions framework is a recent development in machine learning that can associate a reliable measure of confidence with a prediction in any real-world pattern recognition application, including risk-sensitive applications such as medical diagnosis, face recognition, and financial risk prediction. Conformal Predictions for Reliable Machine Learning: Theory, Adaptations and Applications captures the basic theory of the framework, demonstrates how to apply it to real-world problems, and presents several adaptations, including active learning, change detection, and anomaly detecti

  5. Reliability assessment of passive containment isolation system using APSRA methodology

    International Nuclear Information System (INIS)

    Nayak, A.K.; Jain, Vikas; Gartia, M.R.; Srivastava, A.; Prasad, Hari; Anthony, A.; Gaikwad, A.J.; Bhatia, S.; Sinha, R.K.

    2008-01-01

    In this paper, a methodology known as APSRA (Assessment of Passive System ReliAbility) has been employed for evaluation of the reliability of passive systems. The methodology has been applied to the passive containment isolation system (PCIS) of the Indian advanced heavy water reactor (AHWR). In the APSRA methodology, the passive system reliability evaluation is based on the failure probability of the system to carryout the desired function. The methodology first determines the operational characteristics of the system and the failure conditions by assigning a predetermined failure criterion. The failure surface is predicted using a best estimate code considering deviations of the operating parameters from their nominal states, which affect the PCIS performance. APSRA proposes to compare the code predictions with the test data to generate the uncertainties on the failure parameter prediction, which is later considered in the code for accurate prediction of failure surface of the system. Once the failure surface of the system is predicted, the cause of failure is examined through root diagnosis, which occurs mainly due to failure of mechanical components. The failure probability of these components is evaluated through a classical PSA treatment using the generic data. The reliability of the PCIS is evaluated from the probability of availability of the components for the success of the passive containment isolation system

  6. Prediction of software operational reliability using testing environment factor

    International Nuclear Information System (INIS)

    Jung, Hoan Sung

    1995-02-01

    Software reliability is especially important to customers these days. The need to quantify software reliability of safety-critical systems has been received very special attention and the reliability is rated as one of software's most important attributes. Since the software is an intellectual product of human activity and since it is logically complex, the failures are inevitable. No standard models have been established to prove the correctness and to estimate the reliability of software systems by analysis and/or testing. For many years, many researches have focused on the quantification of software reliability and there are many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is on the operational reliability rather than on the test reliability, however. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, testing environment factor comprising the aging factor and the coverage factor are defined in this work to predict the ultimate operational reliability with the failure data. It is by incorporating test environments applied beyond the operational profile into testing environment factor Test reliability can also be estimated with this approach without any model change. The application results are close to the actual data. The approach used in this thesis is expected to be applicable to ultra high reliable software systems that are used in nuclear power plants, airplanes, and other safety-critical applications

  7. Reliability

    OpenAIRE

    Condon, David; Revelle, William

    2017-01-01

    Separating the signal in a test from the irrelevant noise is a challenge for all measurement. Low test reliability limits test validity, attenuates important relationships, and can lead to regression artifacts. Multiple approaches to the assessment and improvement of reliability are discussed. The advantages and disadvantages of several different approaches to reliability are considered. Practical advice on how to assess reliability using open source software is provided.

  8. Predicting Cost/Reliability/Maintainability of Advanced General Aviation Avionics Equipment

    Science.gov (United States)

    Davis, M. R.; Kamins, M.; Mooz, W. E.

    1978-01-01

    A methodology is provided for assisting NASA in estimating the cost, reliability, and maintenance (CRM) requirements for general avionics equipment operating in the 1980's. Practical problems of predicting these factors are examined. The usefulness and short comings of different approaches for modeling coast and reliability estimates are discussed together with special problems caused by the lack of historical data on the cost of maintaining general aviation avionics. Suggestions are offered on how NASA might proceed in assessing cost reliability CRM implications in the absence of reliable generalized predictive models.

  9. Reliability and Probabilistic Risk Assessment - How They Play Together

    Science.gov (United States)

    Safie, Fayssal M.; Stutts, Richard G.; Zhaofeng, Huang

    2015-01-01

    PRA methodology is one of the probabilistic analysis methods that NASA brought from the nuclear industry to assess the risk of LOM, LOV and LOC for launch vehicles. PRA is a system scenario based risk assessment that uses a combination of fault trees, event trees, event sequence diagrams, and probability and statistical data to analyze the risk of a system, a process, or an activity. It is a process designed to answer three basic questions: What can go wrong? How likely is it? What is the severity of the degradation? Since 1986, NASA, along with industry partners, has conducted a number of PRA studies to predict the overall launch vehicles risks. Planning Research Corporation conducted the first of these studies in 1988. In 1995, Science Applications International Corporation (SAIC) conducted a comprehensive PRA study. In July 1996, NASA conducted a two-year study (October 1996 - September 1998) to develop a model that provided the overall Space Shuttle risk and estimates of risk changes due to proposed Space Shuttle upgrades. After the Columbia accident, NASA conducted a PRA on the Shuttle External Tank (ET) foam. This study was the most focused and extensive risk assessment that NASA has conducted in recent years. It used a dynamic, physics-based, integrated system analysis approach to understand the integrated system risk due to ET foam loss in flight. Most recently, a PRA for Ares I launch vehicle has been performed in support of the Constellation program. Reliability, on the other hand, addresses the loss of functions. In a broader sense, reliability engineering is a discipline that involves the application of engineering principles to the design and processing of products, both hardware and software, for meeting product reliability requirements or goals. It is a very broad design-support discipline. It has important interfaces with many other engineering disciplines. Reliability as a figure of merit (i.e. the metric) is the probability that an item will

  10. Life prediction and mechanical reliability of NT551 silicon nitride

    Science.gov (United States)

    Andrews, Mark Jay

    The inert strength and fatigue performance of a diesel engine exhaust valve made from silicon nitride (Si3N4) ceramic were assessed. The Si3N4 characterized in this study was manufactured by Saint Gobain/Norton Industrial Ceramics and was designated as NT551. The evaluation was made utilizing a probabilistic life prediction algorithm that combined censored test specimen strength data with a Weibull distribution function and the stress field of the ceramic valve obtained from finite element analysis. The major assumptions of the life prediction algorithm are that the bulk ceramic material is isotropic and homogeneous and that the strength-limiting flaws are uniformly distributed. The results from mechanical testing indicated that NT551 was not a homogeneous ceramic and that its strength were functions of temperature, loading rate, and machining orientation. Fractographic analysis identified four different failure modes; 2 were identified as inhomogeneities that were located throughout the bulk of NT551 and were due to processing operations. The fractographic analysis concluded that the strength degradation of NT551 observed from the temperature and loading rate test parameters was due to a change of state that occurred in its secondary phase. Pristine and engine-tested valves made from NT551 were loaded to failure and the inert strengths were obtained. Fractographic analysis of the valves identified the same four failure mechanisms as found with the test specimens. The fatigue performance and the inert strength of the Si3N 4 valves were assessed from censored and uncensored test specimen strength data, respectively. The inert strength failure probability predictions were compared to the inert strength of the Si3N4 valves. The inert strength failure probability predictions were more conservative than the strength of the valves. The lack of correlation between predicted and actual valve strength was due to the nonuniform distribution of inhomogeneities present in NT

  11. Methodology for reliability based condition assessment

    International Nuclear Information System (INIS)

    Mori, Y.; Ellingwood, B.

    1993-08-01

    Structures in nuclear power plants may be exposed to aggressive environmental effects that cause their strength to decrease over an extended period of service. A major concern in evaluating the continued service for such structures is to ensure that in their current condition they are able to withstand future extreme load events during the intended service life with a level of reliability sufficient for public safety. This report describes a methodology to facilitate quantitative assessments of current and future structural reliability and performance of structures in nuclear power plants. This methodology takes into account the nature of past and future loads, and randomness in strength and in degradation resulting from environmental factors. An adaptive Monte Carlo simulation procedure is used to evaluate time-dependent system reliability. The time-dependent reliability is sensitive to the time-varying load characteristics and to the choice of initial strength and strength degradation models but not to correlation in component strengths within a system. Inspection/maintenance strategies are identified that minimize the expected future costs of keeping the failure probability of a structure at or below an established target failure probability during its anticipated service period

  12. Operational human performance reliability assessment (OHPRA)

    International Nuclear Information System (INIS)

    Haas, P.M.; Swanson, P.J.; Connelly, E.M.

    1993-01-01

    Operational Human Performance Reliability Assessment (OHPRA) is an approach for assessing human performance that is being developed in response to demands from modern process industries for practical and effective tools to assess and improve human performance, and therefore overall system performance and safety. The single most distinguishing feature of the approach is that is defines human performance in open-quotes operationalclose quotes terms. OHPRA is focused not on generation of human error probabilities, but on practical analysis of human performance to aid management in (1) identifying open-quotes fixableclose quotes problems and (2) providing input on the importance and nature of potential improvements. Development of the model in progress uses a unique approach for eliciting expert strategies for assessing performance. A PC-based model incorporating this expertise is planned. A preliminary version of the approach has already been used successfully to identify practical human performance problems in reactor and chemical process plant operations

  13. Reliability assessment of nuclear structural systems

    International Nuclear Information System (INIS)

    Reich, M.; Hwang, H.

    1983-01-01

    Reliability assessment of nuclear structural systems has been receiving more emphasis over the last few years. This paper deals with the recent progress made by the Structural Analysis Division of Brookhaven National Laboratory (BNL), in the development of a probability-based reliability analysis methodology for safety evaluation of reactor containments and other seismic category I structures. An important feature of this methodology is the incorporation of finite element analysis and random vibration theory. By utilizing this method, it is possible to evaluate the safety of nuclear structures under various static and dynamic loads in terms of limit state probability. Progress in other related areas, such as the establishment of probabilistic characteristics for various loads and structural resistance, are also described. Results of an application of the methodology to a realistic reinforced concrete containment subjected to dead and live loads, accidental internal pressures and earthquake ground accelerations are presented

  14. Towards early software reliability prediction for computer forensic tools (case study).

    Science.gov (United States)

    Abu Talib, Manar

    2016-01-01

    Versatility, flexibility and robustness are essential requirements for software forensic tools. Researchers and practitioners need to put more effort into assessing this type of tool. A Markov model is a robust means for analyzing and anticipating the functioning of an advanced component based system. It is used, for instance, to analyze the reliability of the state machines of real time reactive systems. This research extends the architecture-based software reliability prediction model for computer forensic tools, which is based on Markov chains and COSMIC-FFP. Basically, every part of the computer forensic tool is linked to a discrete time Markov chain. If this can be done, then a probabilistic analysis by Markov chains can be performed to analyze the reliability of the components and of the whole tool. The purposes of the proposed reliability assessment method are to evaluate the tool's reliability in the early phases of its development, to improve the reliability assessment process for large computer forensic tools over time, and to compare alternative tool designs. The reliability analysis can assist designers in choosing the most reliable topology for the components, which can maximize the reliability of the tool and meet the expected reliability level specified by the end-user. The approach of assessing component-based tool reliability in the COSMIC-FFP context is illustrated with the Forensic Toolkit Imager case study.

  15. A comparative evaluation of five human reliability assessment techniques

    International Nuclear Information System (INIS)

    Kirwan, B.

    1988-01-01

    A field experiment was undertaken to evaluate the accuracy, usefulness, and resources requirements of five human reliability quantification techniques (Techniques for Human Error Rate Prediction (THERP); Paired Comparisons, Human Error Assessment and Reduction Technique (HEART), Success Liklihood Index Method (SLIM)-Multi Attribute Utility Decomposition (MAUD), and Absolute Probability Judgement). This was achieved by assessing technique predictions against a set of known human error probabilities, and by comparing their predictions on a set of five realistic Probabilisitc Risk Assessment (PRA) human error. On a combined measure of accuracy THERP and Absolute Probability Judgement performed best, whilst HEART showed indications of accuracy and was lower in resources usage than other techniques. HEART and THERP both appear to benefit from using trained assessors in order to obtain the best results. SLIM and Paired Comparisons require further research on achieving a robust calibration relationship between their scale values and absolute probabilities. (author)

  16. Human reliability in probabilistic safety assessments

    International Nuclear Information System (INIS)

    Nunez Mendez, J.

    1989-01-01

    Nowadays a growing interest in medioambiental aspects is detected in our country. It implies an assessment of the risk involved in the industrial processess and installations in order to determine if those are into the acceptable limits. In these safety assessments, among which PSA (Probabilistic Safety Assessments), can be pointed out the role played by the human being in the system is one of the more relevant subjects. (This relevance has been demostrated in the accidents happenned). However in Spain there aren't manuals specifically dedicated to asses the human contribution to risk in the frame of PSAs. This report aims to improve this situation providing: a) a theoretical background to help the reader in the understanding of the nature of the human error, b) a guide to carry out a Human Reliability Analysis and c) a selected overwiev of the techniques and methodologies currently applied in this area. (Author)

  17. Human Reliability in Probabilistic Safety Assessments

    International Nuclear Information System (INIS)

    Nunez Mendez, J.

    1989-01-01

    Nowadays a growing interest in environmental aspects is detected in our country. It implies an assessment of the risk involved in the industrial processes and installations in order to determine if those are into the acceptable limits. In these safety assessments, among which PSA (Probabilistic Safety Assessments), can be pointed out the role played by the human being in the system is one of the more relevant subjects (This relevance has been demonstrated in the accidents happened) . However, in Spain there aren't manuals specifically dedicated to asses the human contribution to risk in the frame of PSAs. This report aims to improve this situation providing: a) a theoretical background to help the reader in the understanding of the nature of the human error, b) a quid to carry out a Human Reliability Analysis and c) a selected overview of the techniques and methodologies currently applied in this area. (Author) 20 refs

  18. Complex method to calculate objective assessments of information systems protection to improve expert assessments reliability

    Science.gov (United States)

    Abdenov, A. Zh; Trushin, V. A.; Abdenova, G. A.

    2018-01-01

    The paper considers the questions of filling the relevant SIEM nodes based on calculations of objective assessments in order to improve the reliability of subjective expert assessments. The proposed methodology is necessary for the most accurate security risk assessment of information systems. This technique is also intended for the purpose of establishing real-time operational information protection in the enterprise information systems. Risk calculations are based on objective estimates of the adverse events implementation probabilities, predictions of the damage magnitude from information security violations. Calculations of objective assessments are necessary to increase the reliability of the proposed expert assessments.

  19. Performance reliability prediction for thermal aging based on kalman filtering

    International Nuclear Information System (INIS)

    Ren Shuhong; Wen Zhenhua; Xue Fei; Zhao Wensheng

    2015-01-01

    The performance reliability of the nuclear power plant main pipeline that failed due to thermal aging was studied by the performance degradation theory. Firstly, through the data obtained from the accelerated thermal aging experiments, the degradation process of the impact strength and fracture toughness of austenitic stainless steel material of the main pipeline was analyzed. The time-varying performance degradation model based on the state space method was built, and the performance trends were predicted by using Kalman filtering. Then, the multi-parameter and real-time performance reliability prediction model for the main pipeline thermal aging was developed by considering the correlation between the impact properties and fracture toughness, and by using the stochastic process theory. Thus, the thermal aging performance reliability and reliability life of the main pipeline with multi-parameter were obtained, which provides the scientific basis for the optimization management of the aging maintenance decision making for nuclear power plant main pipelines. (authors)

  20. Student Precision and Reliability of the Team Sport Assessment in ...

    African Journals Online (AJOL)

    TSAP) and formative assessment of invasion sport. The specific objectives were to determine the degree of agreement among expert observers, inter-observer reliability (internal consistency), and intra observer reliability (temporal reliability).

  1. Study of redundant Models in reliability prediction of HXMT's HES

    International Nuclear Information System (INIS)

    Wang Jinming; Liu Congzhan; Zhang Zhi; Ji Jianfeng

    2010-01-01

    Two redundant equipment structures of HXMT's HES are proposed firstly, the block backup and dual system cold-redundancy. Then prediction of the reliability is made by using parts count method. Research of comparison and analysis is also performed on the two proposals. A conclusion is drawn that a higher reliability and longer service life could be offered by taking a redundant equipment structure of block backup. (authors)

  2. Reliability Assessment of Transformerless PV Inverters considering Mission Profiles

    Directory of Open Access Journals (Sweden)

    Yongheng Yang

    2015-01-01

    Full Text Available Due to the small volume and high efficiency, transformerless inverters have gained much popularity in grid-connected PV applications, where minimizing leakage current injection is mandatory. This can be achieved by either modifying the modulation schemes or adding extra power switching devices, resulting in an uneven distribution of the power losses on the switching devices. Consequently, the device thermal loading is redistributed and thus may alter the entire inverter reliability performance, especially under a long-term operation. In this consideration, this paper assesses the device reliability of three transformerless inverters under a yearly mission profile (i.e., solar irradiance and ambient temperature. The mission profile is translated to device thermal loading, which is used for lifetime prediction. Comparison results reveal the lifetime mismatches among the power switching devices operating under the same condition, which offers new thoughts for a robust design and a reliable operation of grid-connected transformerless PV inverters with high efficiency.

  3. Methodologies of the hardware reliability prediction for PSA of digital I and C systems

    International Nuclear Information System (INIS)

    Jung, H. S.; Sung, T. Y.; Eom, H. S.; Park, J. K.; Kang, H. G.; Park, J.

    2000-09-01

    Digital I and C systems are being used widely in the Non-safety systems of the NPP and they are expanding their applications to safety critical systems. The regulatory body shifts their policy to risk based and may require Probabilistic Safety Assessment for the digital I and C systems. But there is no established reliability prediction methodology for the digital I and C systems including both software and hardware yet. This survey report includes a lot of reliability prediction methods for electronic systems in view of hardware. Each method has both the strong and the weak points. This report provides the state-of-art of prediction methods and focus on Bellcore method and MIL-HDBK-217F method in deeply. The reliability analysis models are reviewed and discussed to help analysts. Also this report includes state-of-art of software tools that are supporting reliability prediction

  4. Methodologies of the hardware reliability prediction for PSA of digital I and C systems

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H. S.; Sung, T. Y.; Eom, H. S.; Park, J. K.; Kang, H. G.; Park, J

    2000-09-01

    Digital I and C systems are being used widely in the Non-safety systems of the NPP and they are expanding their applications to safety critical systems. The regulatory body shifts their policy to risk based and may require Probabilistic Safety Assessment for the digital I and C systems. But there is no established reliability prediction methodology for the digital I and C systems including both software and hardware yet. This survey report includes a lot of reliability prediction methods for electronic systems in view of hardware. Each method has both the strong and the weak points. This report provides the state-of-art of prediction methods and focus on Bellcore method and MIL-HDBK-217F method in deeply. The reliability analysis models are reviewed and discussed to help analysts. Also this report includes state-of-art of software tools that are supporting reliability prediction.

  5. Assessment of physical server reliability in multi cloud computing system

    Science.gov (United States)

    Kalyani, B. J. D.; Rao, Kolasani Ramchand H.

    2018-04-01

    Business organizations nowadays functioning with more than one cloud provider. By spreading cloud deployment across multiple service providers, it creates space for competitive prices that minimize the burden on enterprises spending budget. To assess the software reliability of multi cloud application layered software reliability assessment paradigm is considered with three levels of abstractions application layer, virtualization layer, and server layer. The reliability of each layer is assessed separately and is combined to get the reliability of multi-cloud computing application. In this paper, we focused on how to assess the reliability of server layer with required algorithms and explore the steps in the assessment of server reliability.

  6. Reliability data collection and use in risk and availability assessment

    International Nuclear Information System (INIS)

    Colombari, V.

    1989-01-01

    For EuReDatA it is a prevailing objective to initiate and support contact between experts, companies and institutions active in reliability engineering and research. Main topics of this 6th EuReDatA Conference are: Reliability data banks; incidents data banks; common cause data; source and propagation of uncertainties; computer aided risk analysis; reliability and incidents data acquisition and processing; human reliability; probabilistic safety and availability assessment; feedback of reliability into system design; data fusion; reliability modeling and techniques; structural and mechanical reliability; consequence modeling; software and electronic reliability; reliability tests. Some conference papers are separately indexed in the database. (HP)

  7. [A reliability growth assessment method and its application in the development of equipment in space cabin].

    Science.gov (United States)

    Chen, J D; Sun, H L

    1999-04-01

    Objective. To assess and predict reliability of an equipment dynamically by making full use of various test informations in the development of products. Method. A new reliability growth assessment method based on army material system analysis activity (AMSAA) model was developed. The method is composed of the AMSAA model and test data conversion technology. Result. The assessment and prediction results of a space-borne equipment conform to its expectations. Conclusion. It is suggested that this method should be further researched and popularized.

  8. A comparative study on the HW reliability assessment methods for digital I and C equipment

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hoan Sung; Sung, T. Y.; Eom, H. S.; Park, J. K.; Kang, H. G.; Lee, G. Y. [Korea Atomic Energy Research Institute, Taejeon (Korea); Kim, M. C. [Korea Advanced Institute of Science and Technology, Taejeon (Korea); Jun, S. T. [KHNP, Taejeon (Korea)

    2002-03-01

    It is necessary to predict or to evaluate the reliability of electronic equipment for the probabilistic safety analysis of digital instrument and control equipment. But most databases for the reliability prediction have no data for the up-to-date equipment and the failure modes are not classified. The prediction results for the specific component show different values according to the methods and databases. For boards and systems each method shows different values than others also. This study is for reliability prediction of PDC system for Wolsong NPP1 as a digital I and C equipment. Various reliability prediction methods and failure databases are used in calculation of the reliability to compare the effects of sensitivity and accuracy of each model and database. Many considerations for the reliability assessment of digital systems are derived with the results of this study. 14 refs., 19 figs., 15 tabs. (Author)

  9. Reliability Assessment of Transformerless PV Inverters Considering Mission Profiles

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Blaabjerg, Frede

    2015-01-01

    reliability of three transformerless inverters under a yearly mission profile (i.e., solar irradiance and ambient temperature). The mission profile is translated to device thermal loading, which is used for lifetime prediction. Compar¬ison results reveal the lifetime mismatches among the power switching......Due to the small volume and high efficiency, transformerless inverters have gained much popularity in grid-connected PV applications, where minimizing leakage current injection is mandatory. This can be achieved either by modifying the modulation schemes or adding extra power switching devices......, resulting in an uneven distribution of the power losses on the switching devices. Consequently, the device thermal loading is redis-tributed, and thus may alter the entire inverter reliability performance, especially under a long-term operation. In this consideration, this paper assesses the device...

  10. Reliability of blood pressure measurement and cardiovascular risk prediction

    NARCIS (Netherlands)

    van der Hoeven, N.V.

    2016-01-01

    High blood pressure is one of the leading risk factors for cardiovascular disease, but difficult to reliably assess because there are many factors which can influence blood pressure including stress, exercise or illness. The first part of this thesis focuses on possible ways to improve the

  11. Towards more accurate and reliable predictions for nuclear applications

    International Nuclear Information System (INIS)

    Goriely, S.

    2015-01-01

    The need for nuclear data far from the valley of stability, for applications such as nuclear astrophysics or future nuclear facilities, challenges the robustness as well as the predictive power of present nuclear models. Most of the nuclear data evaluation and prediction are still performed on the basis of phenomenological nuclear models. For the last decades, important progress has been achieved in fundamental nuclear physics, making it now feasible to use more reliable, but also more complex microscopic or semi-microscopic models in the evaluation and prediction of nuclear data for practical applications. In the present contribution, the reliability and accuracy of recent nuclear theories are discussed for most of the relevant quantities needed to estimate reaction cross sections and beta-decay rates, namely nuclear masses, nuclear level densities, gamma-ray strength, fission properties and beta-strength functions. It is shown that nowadays, mean-field models can be tuned at the same level of accuracy as the phenomenological models, renormalized on experimental data if needed, and therefore can replace the phenomenogical inputs in the prediction of nuclear data. While fundamental nuclear physicists keep on improving state-of-the-art models, e.g. within the shell model or ab initio models, nuclear applications could make use of their most recent results as quantitative constraints or guides to improve the predictions in energy or mass domain that will remain inaccessible experimentally. (orig.)

  12. Reliability assessment of creep rupture life for Gr. 91 steel

    International Nuclear Information System (INIS)

    Kim, Woo-Gon; Park, Jae-Young; Kim, Seon-Jin; Jang, Jinsung

    2013-01-01

    Highlights: • Statistical analysis of a number of creep rupture data based on Z parameter. • Determination of the constant C in LM parameter and long-term creep life prediction. • Generation of random variables for Z s and Z cr by Monte-Carlo simulation in a SCRI model. • Examples for design application were reasonably drawn from the viewpoints of reliability. - Abstract: This paper presents reliability assessment of the long-term creep life of Gr. 91 steel, which is a major structural material for high temperature structural components of Generation-IV reactor systems. A number of creep rupture data for Gr. 91 steel were collected through literature surveys, and the long-term creep life was predicted by Larson–Miller parameter. A “Z parameter” method was used to describe the magnitude of the deviation of the creep rupture data to a master curve. A “Service Condition-creep Rupture property Interference (SCRI) model” based on the Z parameter was used to simultaneously consider the scattering of the creep rupture data of materials and the fluctuations of service conditions in reliability assessment. A statistical analysis of the creep rupture data was conducted by the Z parameter. To carry out the SCRI model, a number of random variables for Z s describing service conditions and Z cr describing the dispersion of the creep rupture data were generated using a Monte-Carlo simulation technique. As examples for application, the creep rupture life under a certain service conditions of Gr. 91 steel was reasonably drawn from the viewpoints of reliability

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

    International Nuclear Information System (INIS)

    Ellingwood, B.; Bhattacharya, B.; Zheng, R.

    1996-11-01

    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

  14. Lifetime Reliability Assessment of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed....... Finally the produce is illustrated on 6 existing UK bridges....

  15. Computer-aided reliability and risk assessment

    International Nuclear Information System (INIS)

    Leicht, R.; Wingender, H.J.

    1989-01-01

    Activities in the fields of reliability and risk analyses have led to the development of particular software tools which now are combined in the PC-based integrated CARARA system. The options available in this system cover a wide range of reliability-oriented tasks, like organizing raw failure data in the component/event data bank FDB, performing statistical analysis of those data with the program FDA, managing the resulting parameters in the reliability data bank RDB, and performing fault tree analysis with the fault tree code FTL or evaluating the risk of toxic or radioactive material release with the STAR code. (orig.)

  16. Assessing the reliability of skilled performance

    International Nuclear Information System (INIS)

    Dougherty, E.M.; Collins, E.P.

    1996-01-01

    In some high-hazard military tasks, precision of motor skills is crucial to avoid a risk-sensitive drop or other mishap. Sparse data supports a basic level of reliability for this activity seemingly much lower than typical, individual action, slip-mode errors would yield. A typical occurrence failure rate seems to be of the order of 1 x 10 -5 per opportunity. A speculation is tendered that this represents a difference in kind; that the reliability of skills is a different taxon than previously called out in the typical scheme of human reliability

  17. A Reliable and Valid Survey to Predict a Patient’s Gagging Intensity

    Directory of Open Access Journals (Sweden)

    Casey M. Hearing

    2014-07-01

    Full Text Available Objectives: The aim of this study was to devise a reliable and valid survey to predict the intensity of someone’s gag reflex. Material and Methods: A 10-question Predictive Gagging Survey was created, refined, and tested on 59 undergraduate participants. The questions focused on risk factors and experiences that would indicate the presence and strength of someone’s gag reflex. Reliability was assessed by administering the survey to a group of 17 participants twice, with 3 weeks separating the two administrations. Finally, the survey was given to 25 dental patients. In these cases, patients completed an informed consent form, filled out the survey, and then had a maxillary impression taken while their gagging response was quantified from 1 to 5 on the Fiske and Dickinson Gagging Intensity Index. Results: There was a moderate positive correlation between the Predictive Gagging Survey and Fiske and Dickinson’s Gagging Severity Index, r = +0.64, demonstrating the survey’s validity. Furthermore, the test-retest reliability was r = +0.96, demonstrating the survey’s reliability. Conclusions: The Predictive Gagging Survey is a 10-question survey about gag-related experiences and behaviours. We established that it is a reliable and valid method to assess the strength of someone’s gag reflex.

  18. Data driven CAN node reliability assessment for manufacturing system

    Science.gov (United States)

    Zhang, Leiming; Yuan, Yong; Lei, Yong

    2017-01-01

    The reliability of the Controller Area Network(CAN) is critical to the performance and safety of the system. However, direct bus-off time assessment tools are lacking in practice due to inaccessibility of the node information and the complexity of the node interactions upon errors. In order to measure the mean time to bus-off(MTTB) of all the nodes, a novel data driven node bus-off time assessment method for CAN network is proposed by directly using network error information. First, the corresponding network error event sequence for each node is constructed using multiple-layer network error information. Then, the generalized zero inflated Poisson process(GZIP) model is established for each node based on the error event sequence. Finally, the stochastic model is constructed to predict the MTTB of the node. The accelerated case studies with different error injection rates are conducted on a laboratory network to demonstrate the proposed method, where the network errors are generated by a computer controlled error injection system. Experiment results show that the MTTB of nodes predicted by the proposed method agree well with observations in the case studies. The proposed data driven node time to bus-off assessment method for CAN networks can successfully predict the MTTB of nodes by directly using network error event data.

  19. Different Reliability Assessment Approaches for Wave Energy Converters

    DEFF Research Database (Denmark)

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

    2015-01-01

    Reliability assessments are of importance for wave energy converters (WECs) due to the fact that accessibility might be limited in case of failure and maintenance. These failure rates can be adapted by reliability considerations. There are two different approaches to how reliability can...

  20. Probabilistic assessment of pressure vessel and piping reliability

    International Nuclear Information System (INIS)

    Sundararajan, C.

    1986-01-01

    The paper presents a critical review of the state-of-the-art in probabilistic assessment of pressure vessel and piping reliability. First the differences in assessing the reliability directly from historical failure data and indirectly by a probabilistic analysis of the failure phenomenon are discussed and the advantages and disadvantages are pointed out. The rest of the paper deals with the latter approach of reliability assessment. Methods of probabilistic reliability assessment are described and major projects where these methods are applied for pressure vessel and piping problems are discussed. An extensive list of references is provided at the end of the paper

  1. Developing Predictive Maintenance Expertise to Improve Plant Equipment Reliability

    International Nuclear Information System (INIS)

    Wurzbach, Richard N.

    2002-01-01

    On-line equipment condition monitoring is a critical component of the world-class production and safety histories of many successful nuclear plant operators. From addressing availability and operability concerns of nuclear safety-related equipment to increasing profitability through support system reliability and reduced maintenance costs, Predictive Maintenance programs have increasingly become a vital contribution to the maintenance and operation decisions of nuclear facilities. In recent years, significant advancements have been made in the quality and portability of many of the instruments being used, and software improvements have been made as well. However, the single most influential component of the success of these programs is the impact of a trained and experienced team of personnel putting this technology to work. Changes in the nature of the power generation industry brought on by competition, mergers, and acquisitions, has taken the historically stable personnel environment of power generation and created a very dynamic situation. As a result, many facilities have seen a significant turnover in personnel in key positions, including predictive maintenance personnel. It has become the challenge for many nuclear operators to maintain the consistent contribution of quality data and information from predictive maintenance that has become important in the overall equipment decision process. These challenges can be met through the implementation of quality training to predictive maintenance personnel and regular updating and re-certification of key technology holders. The use of data management tools and services aid in the sharing of information across sites within an operating company, and with experts who can contribute value-added data management and analysis. The overall effectiveness of predictive maintenance programs can be improved through the incorporation of newly developed comprehensive technology training courses. These courses address the use of

  2. Maintenance personnel performance simulation (MAPPS): a model for predicting maintenance performance reliability in nuclear power plants

    International Nuclear Information System (INIS)

    Knee, H.E.; Krois, P.A.; Haas, P.M.; Siegel, A.I.; Ryan, T.G.

    1983-01-01

    The NRC has developed a structured, quantitative, predictive methodology in the form of a computerized simulation model for assessing maintainer task performance. Objective of the overall program is to develop, validate, and disseminate a practical, useful, and acceptable methodology for the quantitative assessment of NPP maintenance personnel reliability. The program was organized into four phases: (1) scoping study, (2) model development, (3) model evaluation, and (4) model dissemination. The program is currently nearing completion of Phase 2 - Model Development

  3. Preliminary investigation on reliability assessment of passive safety system

    International Nuclear Information System (INIS)

    Huang Changfan; Kuang Bo

    2012-01-01

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

  4. Reliability assessment of underground shaft closure

    International Nuclear Information System (INIS)

    Fossum, A.F.; Munson, D.E.

    1994-01-01

    The intent of the WIPP, being constructed in the bedded geologic salt deposits of Southeastern New Mexico, is to provide the technological basis for the safe disposal of radioactive Transuranic (TRU) wastes generated by the defense programs of the United States. In determining this technological basis, advanced reliability and structural analysis techniques are used to determine the probability of time-to-closure of a hypothetical underground shaft located in an argillaceous salt formation and filled with compacted crushed salt. Before being filled with crushed salt for sealing, the shaft provides access to an underground facility. Reliable closure of the shaft depends upon the sealing of the shaft through creep closure and recompaction of crushed backfill. Appropriate methods are demonstrated to calculate cumulative distribution functions of the closure based on laboratory determined random variable uncertainty in salt creep properties

  5. Risk and reliability assessment for telecommunications networks

    Energy Technology Data Exchange (ETDEWEB)

    Wyss, G.D.; Schriner, H.K.; Gaylor, T.R.

    1996-08-01

    Sandia National Laboratories has assembled an interdisciplinary team to explore the applicability of probabilistic logic modeling (PLM) techniques to model network reliability for a wide variety of communications network architectures. The authors have found that the reliability and failure modes of current generation network technologies can be effectively modeled using fault tree PLM techniques. They have developed a ``plug-and-play`` fault tree analysis methodology that can be used to model connectivity and the provision of network services in a wide variety of current generation network architectures. They have also developed an efficient search algorithm that can be used to determine the minimal cut sets of an arbitrarily-interconnected (non-hierarchical) network without the construction of a fault tree model. This paper provides an overview of these modeling techniques and describes how they are applied to networks that exhibit hybrid network structures (i.e., a network in which some areas are hierarchical and some areas are not hierarchical).

  6. Structural reliability analysis and seismic risk assessment

    International Nuclear Information System (INIS)

    Hwang, H.; Reich, M.; Shinozuka, M.

    1984-01-01

    This paper presents a reliability analysis method for safety evaluation of nuclear structures. By utilizing this method, it is possible to estimate the limit state probability in the lifetime of structures and to generate analytically the fragility curves for PRA studies. The earthquake ground acceleration, in this approach, is represented by a segment of stationary Gaussian process with a zero mean and a Kanai-Tajimi Spectrum. All possible seismic hazard at a site represented by a hazard curve is also taken into consideration. Furthermore, the limit state of a structure is analytically defined and the corresponding limit state surface is then established. Finally, the fragility curve is generated and the limit state probability is evaluated. In this paper, using a realistic reinforced concrete containment as an example, results of the reliability analysis of the containment subjected to dead load, live load and ground earthquake acceleration are presented and a fragility curve for PRA studies is also constructed

  7. Suprahyoid Muscle Complex: A Reliable Neural Assessment Tool For Dysphagia?

    DEFF Research Database (Denmark)

    Kothari, Mohit; Stubbs, Peter William; Pedersen, Asger Roer

    be a non-invasive reliable neural assessment tool for patients with dysphagia. Objective: To investigate the possibility of using the suprahyoid muscle complex (SMC) using surface electromyography (sEMG) to assess changes to neural pathways by determining the reliability of measurements in healthy...

  8. Reliability of assessment of adherence to an antimicrobial treatment guideline

    NARCIS (Netherlands)

    Mol, PGM; Gans, ROB; Panday, PVN; Degener, JE; Laseur, M; Haaijer-Ruskamp, FM

    Assessment procedures for adherence to a guideline must be reliable and credible. The aim of this study was to explore the reliability of assessment of adherence, taking account of the professional backgrounds of the observers. A secondary analysis explored the impact of case characteristics on

  9. Reliability assessment using the concept of possibility

    International Nuclear Information System (INIS)

    Ping, R.; Zhao, G.

    1994-01-01

    The role of the possibility theory in the quantitative approach to the reliability of large scale systems, in particular man-machine systems, is discussed. According to the original idea due to professor L.A. Zadeh, an error rate may be associated with a possibility distribution and a probability distribution. They describe the potentiallity and the actuality for error. This is especially important for the analysis of big accidents

  10. Reliability of computerized cephalometric outcome predictions of mandibular set-back surgery

    Directory of Open Access Journals (Sweden)

    Stefanović Neda

    2011-01-01

    Full Text Available Introduction. A successful treatment outcome in dentofacial deformity patients commonly requires combined orthodontic-surgical therapy. This enables us to overcome functional, aesthetic and psychological problems. Since most patients state aesthetics as the primary motive for seeking therapy, cephalometric predictions of treatment outcome have become the essential part of treatment planning, especially in combined orthodontic-surgical cases. Objective. The aim of this study was to evaluate the validity and reliability of computerized orthognathic surgery outcome predictions generated using the Nemotec Dental Studio NX 2005 software. Methods. The sample of the study consisted of 31 patients diagnosed with mandibular prognathism who were surgically treated at the Hospital for Maxillofacial Surgery in Belgrade. Investigation was done on lateral cephalograms made before and after surgical treatment. Cephalograms were digitized and analyzed using computer software. According to measurements made on superimposed pre- and postsurgical cephalograms, the patients were retreated within the software and the predictions were assessed by measuring seven angular and three linear parameters. Prediction measurements were then compared with the actual outcome. Results. Results showed statistically significant changes between posttreatment and predicted values for parameters referring to lower lip and mentolabial sulcus position. Conclusion. Computerized cephalometric predictions for hard-tissue structures in the sagittal and vertical planes, as well as the VTO parameters, generated using the Nemotec Dental Studio NX 2005 software are reliable, while lower lip and mentolabial sulcus position predictions are not reliable enough.

  11. Test-retest reliability and predictive validity of the Implicit Association Test in children.

    Science.gov (United States)

    Rae, James R; Olson, Kristina R

    2018-02-01

    The Implicit Association Test (IAT) is increasingly used in developmental research despite minimal evidence of whether children's IAT scores are reliable across time or predictive of behavior. When test-retest reliability and predictive validity have been assessed, the results have been mixed, and because these studies have differed on many factors simultaneously (lag-time between testing administrations, domain, etc.), it is difficult to discern what factors may explain variability in existing test-retest reliability and predictive validity estimates. Across five studies (total N = 519; ages 6- to 11-years-old), we manipulated two factors that have varied in previous developmental research-lag-time and domain. An internal meta-analysis of these studies revealed that, across three different methods of analyzing the data, mean test-retest (rs of .48, .38, and .34) and predictive validity (rs of .46, .20, and .10) effect sizes were significantly greater than zero. While lag-time did not moderate the magnitude of test-retest coefficients, whether we observed domain differences in test-retest reliability and predictive validity estimates was contingent on other factors, such as how we scored the IAT or whether we included estimates from a unique sample (i.e., a sample containing gender typical and gender diverse children). Recommendations are made for developmental researchers that utilize the IAT in their research. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  12. Extrapolation Method for System Reliability Assessment

    DEFF Research Database (Denmark)

    Qin, Jianjun; Nishijima, Kazuyoshi; Faber, Michael Havbro

    2012-01-01

    of integrals with scaled domains. The performance of this class of approximation depends on the approach applied for the scaling and the functional form utilized for the extrapolation. A scheme for this task is derived here taking basis in the theory of asymptotic solutions to multinormal probability integrals......The present paper presents a new scheme for probability integral solution for system reliability analysis, which takes basis in the approaches by Naess et al. (2009) and Bucher (2009). The idea is to evaluate the probability integral by extrapolation, based on a sequence of MC approximations...... that the proposed scheme is efficient and adds to generality for this class of approximations for probability integrals....

  13. Reliability and maintainability assessment factors for reliable fault-tolerant systems

    Science.gov (United States)

    Bavuso, S. J.

    1984-01-01

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

  14. Analysis and assessment of water treatment plant reliability

    Directory of Open Access Journals (Sweden)

    Szpak Dawid

    2017-03-01

    Full Text Available The subject of the publication is the analysis and assessment of the reliability of the surface water treatment plant (WTP. In the study the one parameter method of reliability assessment was used. Based on the flow sheet derived from the water company the reliability scheme of the analysed WTP was prepared. On the basis of the daily WTP work report the availability index Kg for the individual elements included in the WTP, was determined. Then, based on the developed reliability scheme showing the interrelationships between elements, the availability index Kg for the whole WTP was determined. The obtained value of the availability index Kg was compared with the criteria values.

  15. Reliability of dipstick assay in predicting urinary tract infection

    Directory of Open Access Journals (Sweden)

    Anith Kumar Mambatta

    2015-01-01

    Full Text Available Aims: Urine dipstick analysis is a quick, cheap and a useful test in predicting Urinary Tract Infection (UTI in hospitalized patients. Our aim is to evaluate the reliability (sensitivity of urine dipstick analysis against urine culture in the diagnosis of UTI. Materials and Methods: Patients admitted to our hospital suspected of having UTI, with positive urine cultures were included in this study from a 2-year period (January 2011 to December 2012. Dipstick urinalysis was done using multistix 10 SG (Siemens and clinitek advantus analyzer. The sensitivity of dipstick nitrites, leukocyte esterase and blood in these culture-positive UTI patients was calculated retrospectively. Results: Urine dipstick analysis of 635 urine culture-positive patients was studied. The sensitivity of nitrite alone and leukocyte esterase alone were 23.31% and 48.5%, respectively. The sensitivity of blood alone in positive urine culture was 63.94%, which was the highest sensitivity for a single screening test. The presence of leukocyte esterase and/or blood increased the sensitivity to 72.28%. The sensitivity was found to be the highest when nitrite, leukocyte and blood were considered together. Conclusions: Nitrite test and leukocyte esterase test when used individually is not reliable to rule out UTI. Hence, symptomatic UTI patients with negative dipstick assay should be subjected to urine culture for a proper management.

  16. Assessing the Impact of Imperfect Diagnosis on Service Reliability

    DEFF Research Database (Denmark)

    Grønbæk, Lars Jesper; Schwefel, Hans-Peter; Kjærgaard, Jens Kristian

    2010-01-01

    , representative diagnosis performance metrics have been defined and their closed-form solutions obtained for the Markov model. These equations enable model parameterization from traces of implemented diagnosis components. The diagnosis model has been integrated in a reliability model assessing the impact...... of the diagnosis functions for the studied reliability problem. In a simulation study we finally analyze trade-off properties of diagnosis heuristics from literature, map them to the analytic Markov model, and investigate its suitability for service reliability optimization....

  17. The application of cognitive models to the evaluation and prediction of human reliability

    International Nuclear Information System (INIS)

    Embrey, D.E.; Reason, J.T.

    1986-01-01

    The first section of the paper provides a brief overview of a number of important principles relevant to human reliability modeling that have emerged from cognitive models, and presents a synthesis of these approaches in the form of a Generic Error Modeling System (GEMS). The next section illustrates the application of GEMS to some well known nuclear power plant (NPP) incidents in which human error was a major contributor. The way in which design recommendations can emerge from analyses of this type is illustrated. The third section describes the use of cognitive models in the classification of human errors for prediction and data collection purposes. The final section addresses the predictive modeling of human error as part of human reliability assessment in Probabilistic Risk Assessment

  18. Probabilistic simulation applications to reliability assessments

    International Nuclear Information System (INIS)

    Miller, Ian; Nutt, Mark W.; Hill, Ralph S. III

    2003-01-01

    Probabilistic risk/reliability (PRA) analyses for engineered systems are conventionally based on fault-tree methods. These methods are mature and efficient, and are well suited to systems consisting of interacting components with known, low probabilities of failure. Even complex systems, such as nuclear power plants or aircraft, are modeled by the careful application of these approaches. However, for systems that may evolve in complex and nonlinear ways, and where the performance of components may be a sensitive function of the history of their working environments, fault-tree methods can be very demanding. This paper proposes an alternative method of evaluating such systems, based on probabilistic simulation using intelligent software objects to represent the components of such systems. Using a Monte Carlo approach, simulation models can be constructed from relatively simple interacting objects that capture the essential behavior of the components that they represent. Such models are capable of reflecting the complex behaviors of the systems that they represent in a natural and realistic way. (author)

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

    International Nuclear Information System (INIS)

    Locks, M.O.

    1978-01-01

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

  20. 75 FR 66038 - Planning Resource Adequacy Assessment Reliability Standard

    Science.gov (United States)

    2010-10-27

    ..., providing a common framework for resource adequacy analysis, assessment, and documentation) effectively and...://www.nerc.com/commondocs.php?cd=2 . D. Proposed Effective Date 24. Proposed regional Reliability...

  1. Improving the reliability of fishery predictions under climate change

    DEFF Research Database (Denmark)

    Brander, Keith

    2015-01-01

    The increasing number of publications assessing impacts of climate change on marine ecosystems and fisheries attests to rising scientific and public interest. A selection of recent papers, dealing more with biological than social and economic aspects, is reviewed here, with particular attention...... to the reliability of projections of climate impacts on future fishery yields. The 2014 Intergovernmental Panel on Climate Change (IPCC) report expresses high confidence in projections that mid- and high-latitude fish catch potential will increase by 2050 and medium confidence that low-latitude catch potential...... understanding of climate impacts, such as how to improve coupled models from physics to fish and how to strengthen confidence in analysis of time series...

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

    International Nuclear Information System (INIS)

    Son, Young Kap

    2011-01-01

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

  3. Reliability and comparison of acromion assessment techniques on x-ray and magnetic resonance imaging (reliability of acromion assessment techniques)

    International Nuclear Information System (INIS)

    Viskontas, D.G.; MacDermid, J.C.; Drosdowech, D.S.; Garvin, G.J.; Romano, W.M.; Faber, K.J.

    2005-01-01

    To determine the reliability and correlation of plain radiography and magnetic resonance imaging (MRI) in the assessment of acromion morphology. Materials and Methods: Acromion morphology was assessed using the lateral acromion angle (LAA) and the acromion-humeral interval (AHI). Thirty patients who had x-rays and MRI for impingement syndrome were included. Six blinded observers assessed the acromion morphology subjectively and objectively. Results: Neither acromion assessment technique demonstrated a positive correlation (kappa and intraclass coefficient 0.55) when measured objectively by experienced observers. Conclusion: The LAA and the AHI are both reliable acromion assessment techniques on X-ray and MRI when measured objectively and by experienced observers. (author)

  4. Sequential optimization and reliability assessment method for metal forming processes

    International Nuclear Information System (INIS)

    Sahai, Atul; Schramm, Uwe; Buranathiti, Thaweepat; Chen Wei; Cao Jian; Xia, Cedric Z.

    2004-01-01

    Uncertainty is inevitable in any design process. The uncertainty could be due to the variations in geometry of the part, material properties or due to the lack of knowledge about the phenomena being modeled itself. Deterministic design optimization does not take uncertainty into account and worst case scenario assumptions lead to vastly over conservative design. Probabilistic design, such as reliability-based design and robust design, offers tools for making robust and reliable decisions under the presence of uncertainty in the design process. Probabilistic design optimization often involves double-loop procedure for optimization and iterative probabilistic assessment. This results in high computational demand. The high computational demand can be reduced by replacing computationally intensive simulation models with less costly surrogate models and by employing Sequential Optimization and reliability assessment (SORA) method. The SORA method uses a single-loop strategy with a series of cycles of deterministic optimization and reliability assessment. The deterministic optimization and reliability assessment is decoupled in each cycle. This leads to quick improvement of design from one cycle to other and increase in computational efficiency. This paper demonstrates the effectiveness of Sequential Optimization and Reliability Assessment (SORA) method when applied to designing a sheet metal flanging process. Surrogate models are used as less costly approximations to the computationally expensive Finite Element simulations

  5. The 6-min push test is reliable and predicts low fitness in spinal cord injury.

    Science.gov (United States)

    Cowan, Rachel E; Callahan, Morgan K; Nash, Mark S

    2012-10-01

    The objective of this study is to assess 6-min push test (6MPT) reliability, determine whether the 6MPT is sensitive to fitness differences, and assess if 6MPT distance predicts fitness level in persons with spinal cord injury (SCI) or disease. Forty individuals with SCI who could self-propel a manual wheelchair completed an incremental arm crank peak oxygen consumption assessment and two 6MPTs across 3 d (37% tetraplegia (TP), 63% paraplegia (PP), 85% men, 70% white, 63% Hispanic, mean age = 34 ± 10 yr, mean duration of injury = 13 ± 10 yr, and mean body mass index = 24 ± 5 kg.m). Intraclass correlation and Bland-Altman plots assessed 6MPT distance (m) reliability. Mann-Whitney U test compared 6MPT distance (m) of high and low fitness groups for TP and PP. The fitness status prediction was developed using N = 30 and validated in N = 10 (validation group (VG)). A nonstatistical prediction approach, below or above a threshold distance (TP = 445 m and PP = 604 m), was validated statistically by binomial logistic regression. Accuracy, sensitivity, and specificity were computed to evaluate the threshold approach. Intraclass correlation coefficients exceeded 0.90 for the whole sample and the TP/PP subsets. High fitness persons propelled farther than low fitness persons for both TP/PP (both P < 0.05). Binomial logistic regression (P < 0.008) predicted the same fitness levels in the VG as the threshold approach. In the VG, overall accuracy was 70%. Eighty-six percent of low fitness persons were correctly identified (sensitivity), and 33% of high fitness persons were correctly identified (specificity). The 6MPT may be a useful tool for SCI clinicians and researchers. 6MPT distance demonstrates excellent reliability and is sensitive to differences in fitness level. 6MPT distances less than a threshold distance may be an effective approach to identify low fitness in person with SCI.

  6. Translation, reliability, and clinical utility of the Melbourne Assessment 2.

    Science.gov (United States)

    Gerber, Corinna N; Plebani, Anael; Labruyère, Rob

    2017-10-12

    The aims were to (i) provide a German translation of the Melbourne Assessment 2 (MA2), a quantitative test to measure unilateral upper limb function in children with neurological disabilities and (ii) to evaluate its reliability and aspects of clinical utility. After its translation into German and approval of the back translation by the original authors, the MA2 was performed and videotaped twice with 30 children with neuromotor disorders. For each participant, two raters scored the video of the first test for inter-rater reliability. To determine test-retest reliability, one rater additionally scored the video of the second test while the other rater repeated the scoring of the first video to evaluate intra-rater reliability. Time needed for rater training, test administration, and scoring was recorded. The four subscale scores showed excellent intra-, inter-rater, and test-retest reliability with intraclass correlation coefficients of 0.90-1.00 (95%-confidence intervals 0.78-1.00). Score items revealed substantial to almost perfect intra-rater reliability (weighted kappa k w  = 0.66-1.00) for the more affected side. Score item inter-rater and test-retest reliability of the same extremity were, with one exception, moderate to almost perfect (k w  = 0.42-0.97; k w  = 0.40-0.89). Furthermore, the MA2 was feasible and acceptable for patients and clinicians. The MA2 showed excellent subscale and moderate to almost perfect score item reliability. Implications for Rehabilitation There is a lack of high-quality studies about psychometric properties of upper limb measurement tools in the neuropediatric population. The Melbourne Assessment 2 is a promising tool for reliable measurement of unilateral upper limb movement quality in the neuropediatric population. The Melbourne Assessment 2 is acceptable and practicable to therapists and patients for routine use in clinical care.

  7. Software reliability

    CERN Document Server

    Bendell, A

    1986-01-01

    Software Reliability reviews some fundamental issues of software reliability as well as the techniques, models, and metrics used to predict the reliability of software. Topics covered include fault avoidance, fault removal, and fault tolerance, along with statistical methods for the objective assessment of predictive accuracy. Development cost models and life-cycle cost models are also discussed. This book is divided into eight sections and begins with a chapter on adaptive modeling used to predict software reliability, followed by a discussion on failure rate in software reliability growth mo

  8. Is the Frontal Assessment Battery reliable in ALS patients?

    NARCIS (Netherlands)

    Raaphorst, J.; Beeldman, E.; Jaeger, B.; Schmand, B.A.; Berg, L.H. van den; Weikamp, J.G.; Schelhaas, H.J.; Visser, M. de; Haan, R.J. de

    2013-01-01

    The assessment of frontal functions in ALS patients is important because of the overlap with the behavioural variant of frontotemporal dementia (bvFTD). We investigated the applicability and reliability of the Frontal Assessment Battery (FAB) within a cohort of predominantly prevalent ALS patients.

  9. Photographic assessment of burn size and depth: reliability and validity

    NARCIS (Netherlands)

    Hop, M.; Moues, C.; Bogomolova, K.; Nieuwenhuis, M.; Oen, I.; Middelkoop, E.; Breederveld, R.; de Baar, M.

    2014-01-01

    Objective: The aim of this study was to examine the reliability and validity of using photographs of burns to assess both burn size and depth. Method: Fifty randomly selected photographs taken on day 0-1 post burn were assessed by seven burn experts and eight referring physicians. Inter-rater

  10. Valid and Reliable Science Content Assessments for Science Teachers

    Science.gov (United States)

    Tretter, Thomas R.; Brown, Sherri L.; Bush, William S.; Saderholm, Jon C.; Holmes, Vicki-Lynn

    2013-01-01

    Science teachers' content knowledge is an important influence on student learning, highlighting an ongoing need for programs, and assessments of those programs, designed to support teacher learning of science. Valid and reliable assessments of teacher science knowledge are needed for direct measurement of this crucial variable. This paper…

  11. Reliability and validity of subjective assessment of lumbar lordosis in ...

    African Journals Online (AJOL)

    Radiological assessment of lumbar lordotic curve aids in early diagnosis of conditions even before neurologic changes set in. Objective: To ascertain the level of reliability and validity of subjective assessment of lumbar lordosis in conventional radiography. Design: A blinded, repeated-measures diagnostic test was carried ...

  12. A computational Bayesian approach to dependency assessment in system reliability

    International Nuclear Information System (INIS)

    Yontay, Petek; Pan, Rong

    2016-01-01

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

  13. Sequential decision reliability concept and failure rate assessment

    International Nuclear Information System (INIS)

    Ciftcioglu, O.

    1990-11-01

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

  14. Reliability of sonographic assessment of tendinopathy in tennis elbow.

    Science.gov (United States)

    Poltawski, Leon; Ali, Syed; Jayaram, Vijay; Watson, Tim

    2012-01-01

    To assess the reliability and compute the minimum detectable change using sonographic scales to quantify the extent of pathology and hyperaemia in the common extensor tendon in people with tennis elbow. The lateral elbows of 19 people with tennis elbow were assessed sonographically twice, 1-2 weeks apart. Greyscale and power Doppler images were recorded for subsequent rating of abnormalities. Tendon thickening, hypoechogenicity, fibrillar disruption and calcification were each rated on four-point scales, and scores were summed to provide an overall rating of structural abnormality; hyperaemia was scored on a five point scale. Inter-rater reliability was established using the intraclass correlation coefficient (ICC) to compare scores assigned independently to the same set of images by a radiologist and a physiotherapist with training in musculoskeletal imaging. Test-retest reliability was assessed by comparing scores assigned by the physiotherapist to images recorded at the two sessions. The minimum detectable change (MDC) was calculated from the test-retest reliability data. ICC values for inter-rater reliability ranged from 0.35 (95% CI: 0.05, 0.60) for fibrillar disruption to 0.77 (0.55, 0.88) for overall greyscale score, and 0.89 (0.79, 0.95) for hyperaemia. Test-retest reliability ranged from 0.70 (0.48, 0.84) for tendon thickening to 0.82 (0.66, 0.90) for overall greyscale score and 0.86 (0.73, 0.93) for calcification. The MDC for the greyscale total score was 2.0/12 and for the hyperaemia score was 1.1/5. The sonographic scoring system used in this study may be used reliably to quantify tendon abnormalities and change over time. A relatively inexperienced imager can conduct the assessment and use the rating scales reliably.

  15. Design and reliability of a didactic inphographic rubric assessment

    OpenAIRE

    Guzmán-cedillo, Yunuen Ixchel

    2017-01-01

    The objective of this study is to describe design, validity process and reliability of a rubric assessment to evaluate didactic infographics quality. Participants were fifteen judges who participate in different moments of elaboration rubric process; it was made in three process phases: design, settings and reliability determination. Content validity was obtained by percentage agreement between 3 judges by component of the rubric; likewise a Krippendorff’s alpha were applied (a = .710) in pi...

  16. Reliability of histologic assessment in patients with eosinophilic oesophagitis.

    Science.gov (United States)

    Warners, M J; Ambarus, C A; Bredenoord, A J; Verheij, J; Lauwers, G Y; Walsh, J C; Katzka, D A; Nelson, S; van Viegen, T; Furuta, G T; Gupta, S K; Stitt, L; Zou, G; Parker, C E; Shackelton, L M; D Haens, G R; Sandborn, W J; Dellon, E S; Feagan, B G; Collins, M H; Jairath, V; Pai, R K

    2018-04-01

    The validity of the eosinophilic oesophagitis (EoE) histologic scoring system (EoEHSS) has been demonstrated, but only preliminary reliability data exist. Formally assess the reliability of the EoEHSS and additional histologic features. Four expert gastrointestinal pathologists independently reviewed slides from adult patients with EoE (N = 45) twice, in random order, using standardised training materials and scoring conventions for the EoEHSS and additional histologic features agreed upon during a modified Delphi process. Intra- and inter-rater reliability for scoring the EoEHSS, a visual analogue scale (VAS) of overall histopathologic disease severity, and additional histologic features were assessed using intra-class correlation coefficients (ICCs). Almost perfect intra-rater reliability was observed for the composite EoEHSS scores and the VAS. Inter-rater reliability was also almost perfect for the composite EoEHSS scores and substantial for the VAS. Of the EoEHSS items, eosinophilic inflammation was associated with the highest ICC estimates and consistent with almost perfect intra- and inter-rater reliability. With the exception of dyskeratotic epithelial cells and surface epithelial alteration, ICC estimates for the remaining EoEHSS items were above the benchmarks for substantial intra-rater, and moderate inter-rater reliability. Estimation of peak eosinophil count and number of lamina propria eosinophils were associated with the highest ICC estimates among the exploratory items. The composite EoEHSS and most component items are associated with substantial reliability when assessed by central pathologists. Future studies should assess responsiveness of the score to change after a therapeutic intervention to facilitate its use in clinical trials. © 2018 John Wiley & Sons Ltd.

  17. A Novel Risk Scoring System Reliably Predicts Readmission Following Pancreatectomy

    Science.gov (United States)

    Valero, Vicente; Grimm, Joshua C.; Kilic, Arman; Lewis, Russell L.; Tosoian, Jeffrey J.; He, Jin; Griffin, James; Cameron, John L.; Weiss, Matthew J.; Vollmer, Charles M.; Wolfgang, Christopher L.

    2015-01-01

    Background Postoperative readmissions have been proposed by Medicare as a quality metric and may impact provider reimbursement. Since readmission following pancreatectomy is common, we sought to identify factors associated with readmission in order to establish a predictive risk scoring system (RSS). Study Design A retrospective analysis of 2,360 pancreatectomies performed at nine, high-volume pancreatic centers between 2005 and 2011 was performed. Forty-five factors strongly associated with readmission were identified. To derive and validate a RSS, the population was randomly divided into two cohorts in a 4:1 fashion. A multivariable logistic regression model was constructed and scores were assigned based on the relative odds ratio of each independent predictor. A composite Readmission After Pancreatectomy (RAP) score was generated and then stratified to create risk groups. Results Overall, 464 (19.7%) patients were readmitted within 90-days. Eight pre- and postoperative factors, including prior myocardial infarction (OR 2.03), ASA Class ≥ 3 (OR 1.34), dementia (OR 6.22), hemorrhage (OR 1.81), delayed gastric emptying (OR 1.78), surgical site infection (OR 3.31), sepsis (OR 3.10) and short length of stay (OR 1.51), were independently predictive of readmission. The 32-point RAP score generated from the derivation cohort was highly predictive of readmission in the validation cohort (AUC 0.72). The low (0-3), intermediate (4-7) and high risk (>7) groups correlated to 11.7%, 17.5% and 45.4% observed readmission rates, respectively (preadmission following pancreatectomy. Identification of patients with increased risk of readmission using the RAP score will allow efficient resource allocation aimed to attenuate readmission rates. It also has potential to serve as a new metric for comparative research and quality assessment. PMID:25797757

  18. Reliability and Validity of the Load-Velocity Relationship to Predict the 1RM Back Squat.

    Science.gov (United States)

    Banyard, Harry G; Nosaka, Kazunori; Haff, G Gregory

    2017-07-01

    Banyard, HG, Nosaka, K, and Haff, GG. Reliability and validity of the load-velocity relationship to predict the 1RM back squat. J Strength Cond Res 31(7): 1897-1904, 2017-This study investigated the reliability and validity of the load-velocity relationship to predict the free-weight back squat one repetition maximum (1RM). Seventeen strength-trained males performed three 1RM assessments on 3 separate days. All repetitions were performed to full depth with maximal concentric effort. Predicted 1RMs were calculated by entering the mean concentric velocity of the 1RM (V1RM) into an individualized linear regression equation, which was derived from the load-velocity relationship of 3 (20, 40, 60% of 1RM), 4 (20, 40, 60, 80% of 1RM), or 5 (20, 40, 60, 80, 90% of 1RM) incremental warm-up sets. The actual 1RM (140.3 ± 27.2 kg) was very stable between 3 trials (ICC = 0.99; SEM = 2.9 kg; CV = 2.1%; ES = 0.11). Predicted 1RM from 5 warm-up sets up to and including 90% of 1RM was the most reliable (ICC = 0.92; SEM = 8.6 kg; CV = 5.7%; ES = -0.02) and valid (r = 0.93; SEE = 10.6 kg; CV = 7.4%; ES = 0.71) of the predicted 1RM methods. However, all predicted 1RMs were significantly different (p ≤ 0.05; ES = 0.71-1.04) from the actual 1RM. Individual variation for the actual 1RM was small between trials ranging from -5.6 to 4.8% compared with the most accurate predictive method up to 90% of 1RM, which was more variable (-5.5 to 27.8%). Importantly, the V1RM (0.24 ± 0.06 m·s) was unreliable between trials (ICC = 0.42; SEM = 0.05 m·s; CV = 22.5%; ES = 0.14). The load-velocity relationship for the full depth free-weight back squat showed moderate reliability and validity but could not accurately predict 1RM, which was stable between trials. Thus, the load-velocity relationship 1RM prediction method used in this study cannot accurately modify sessional training loads because of large V1RM variability.

  19. Reliable and valid assessment of Lichtenstein hernia repair skills

    DEFF Research Database (Denmark)

    Carlsen, C G; Lindorff Larsen, Karen; Funch-Jensen, P

    2014-01-01

    PURPOSE: Lichtenstein hernia repair is a common surgical procedure and one of the first procedures performed by a surgical trainee. However, formal assessment tools developed for this procedure are few and sparsely validated. The aim of this study was to determine the reliability and validity...... of an assessment tool designed to measure surgical skills in Lichtenstein hernia repair. METHODS: Key issues were identified through a focus group interview. On this basis, an assessment tool with eight items was designed. Ten surgeons and surgical trainees were video recorded while performing Lichtenstein hernia...... a significant difference between the three groups which indicates construct validity, p skills can be assessed blindly by a single rater in a reliable and valid fashion with the new procedure-specific assessment tool. We recommend this tool for future assessment...

  20. [Reliability and validity of the Braden Scale for predicting pressure sore risk].

    Science.gov (United States)

    Boes, C

    2000-12-01

    For more accurate and objective pressure sore risk assessment various risk assessment tools were developed mainly in the USA and Great Britain. The Braden Scale for Predicting Pressure Sore Risk is one such example. By means of a literature analysis of German and English texts referring to the Braden Scale the scientific control criteria reliability and validity will be traced and consequences for application of the scale in Germany will be demonstrated. Analysis of 4 reliability studies shows an exclusive focus on interrater reliability. Further, even though examination of 19 validity studies occurs in many different settings, such examination is limited to the criteria sensitivity and specificity (accuracy). The range of sensitivity and specificity level is 35-100%. The recommended cut off points rank in the field of 10 to 19 points. The studies prove to be not comparable with each other. Furthermore, distortions in these studies can be found which affect accuracy of the scale. The results of the here presented analysis show an insufficient proof for reliability and validity in the American studies. In Germany, the Braden scale has not yet been tested under scientific criteria. Such testing is needed before using the scale in different German settings. During the course of such testing, construction and study procedures of the American studies can be used as a basis as can the problems be identified in the analysis presented below.

  1. Assessment of structural reliability of precast concrete buildings

    Directory of Open Access Journals (Sweden)

    Koyankin Alexandr

    2018-01-01

    Full Text Available Precast housing construction is currently being under rapid development, however, reliability of building structures made from precast reinforced concrete cannot be assessed rationally due to insufficient research data on that subject. In this regard, experimental and numerical studies were conducted to assess structural reliability of precast buildings as described in the given paper. Experimental studies of full-scale and model samples were conducted; numerical studies were held based on finite element models using “Lira” software. The objects under study included fragment of flooring of a building under construction, full-size fragment of flooring, full-scale models of precast cross-beams-to-columns joints and joints between hollow-core floor slabs and precast and cast-in-place cross-beams. Conducted research enabled to perform an objective assessment of structural reliability of precast buildings.

  2. A new measurement of workload in Web application reliability assessment

    Directory of Open Access Journals (Sweden)

    CUI Xia

    2015-02-01

    Full Text Available Web application has been popular in various fields of social life.It becomes more and more important to study the reliability of Web application.In this paper the definition of Web application failure is firstly brought out,and then the definition of Web application reliability.By analyzing data in the IIS server logs and selecting corresponding usage and information delivery failure data,the paper study the feasibility of Web application reliability assessment from the perspective of Web software system based on IIS server logs.Because the usage for a Web site often has certain regularity,a new measurement of workload in Web application reliability assessment is raised.In this method,the unit is removed by weighted average technique;and the weights are assessed by setting objective function and optimization.Finally an experiment was raised for validation.The experiment result shows the assessment of Web application reliability base on the new workload is better.

  3. ASSESSING AND COMBINING RELIABILITY OF PROTEIN INTERACTION SOURCES

    Science.gov (United States)

    LEACH, SONIA; GABOW, AARON; HUNTER, LAWRENCE; GOLDBERG, DEBRA S.

    2008-01-01

    Integrating diverse sources of interaction information to create protein networks requires strategies sensitive to differences in accuracy and coverage of each source. Previous integration approaches calculate reliabilities of protein interaction information sources based on congruity to a designated ‘gold standard.’ In this paper, we provide a comparison of the two most popular existing approaches and propose a novel alternative for assessing reliabilities which does not require a gold standard. We identify a new method for combining the resultant reliabilities and compare it against an existing method. Further, we propose an extrinsic approach to evaluation of reliability estimates, considering their influence on the downstream tasks of inferring protein function and learning regulatory networks from expression data. Results using this evaluation method show 1) our method for reliability estimation is an attractive alternative to those requiring a gold standard and 2) the new method for combining reliabilities is less sensitive to noise in reliability assignments than the similar existing technique. PMID:17990508

  4. Assessment of the reliability of ultrasonic inspection methods

    International Nuclear Information System (INIS)

    Haines, N.F.; Langston, D.B.; Green, A.J.; Wilson, R.

    1982-01-01

    The reliability of NDT techniques has remained an open question for many years. A reliable technique may be defined as one that, when rigorously applied by a number of inspection teams, consistently finds then correctly sizes all defects of concern. In this paper we report an assessment of the reliability of defect detection by manual ultrasonic methods applied to the inspection of thick section pressure vessel weldments. Initially we consider the available data relating to the inherent physical capabilities of ultrasonic techniques to detect cracks in weldment and then, independently, we assess the likely variability in team to team performance when several teams are asked to follow the same specified test procedure. The two aspects of 'capability' and 'variability' are brought together to provide quantitative estimates of the overall reliability of ultrasonic inspection of thick section pressure vessel weldments based on currently existing data. The final section of the paper considers current research programmes on reliability and presents a view on how these will help to further improve NDT reliability. (author)

  5. Reliable and valid assessment of performance in thoracoscopy

    DEFF Research Database (Denmark)

    Konge, Lars; Lehnert, Per; Hansen, Henrik Jessen

    2012-01-01

    BACKGROUND: As we move toward competency-based education in medicine, we have lagged in developing competency-based evaluation methods. In the era of minimally invasive surgery, there is a need for a reliable and valid tool dedicated to measure competence in video-assisted thoracoscopic surgery....... The purpose of this study is to create such an assessment tool, and to explore its reliability and validity. METHODS: An expert group of physicians created an assessment tool consisting of 10 items rated on a five-point rating scale. The following factors were included: economy and confidence of movement...

  6. Reliability assessment for safety critical systems by statistical random testing

    International Nuclear Information System (INIS)

    Mills, S.E.

    1995-11-01

    In this report we present an overview of reliability assessment for software and focus on some basic aspects of assessing reliability for safety critical systems by statistical random testing. We also discuss possible deviations from some essential assumptions on which the general methodology is based. These deviations appear quite likely in practical applications. We present and discuss possible remedies and adjustments and then undertake applying this methodology to a portion of the SDS1 software. We also indicate shortcomings of the methodology and possible avenues to address to follow to address these problems. (author). 128 refs., 11 tabs., 31 figs

  7. Reliability assessment for safety critical systems by statistical random testing

    Energy Technology Data Exchange (ETDEWEB)

    Mills, S E [Carleton Univ., Ottawa, ON (Canada). Statistical Consulting Centre

    1995-11-01

    In this report we present an overview of reliability assessment for software and focus on some basic aspects of assessing reliability for safety critical systems by statistical random testing. We also discuss possible deviations from some essential assumptions on which the general methodology is based. These deviations appear quite likely in practical applications. We present and discuss possible remedies and adjustments and then undertake applying this methodology to a portion of the SDS1 software. We also indicate shortcomings of the methodology and possible avenues to address to follow to address these problems. (author). 128 refs., 11 tabs., 31 figs.

  8. A critique of reliability prediction techniques for avionics applications

    Directory of Open Access Journals (Sweden)

    Guru Prasad PANDIAN

    2018-01-01

    Full Text Available Avionics (aeronautics and aerospace industries must rely on components and systems of demonstrated high reliability. For this, handbook-based methods have been traditionally used to design for reliability, develop test plans, and define maintenance requirements and sustainment logistics. However, these methods have been criticized as flawed and leading to inaccurate and misleading results. In its recent report on enhancing defense system reliability, the U.S. National Academy of Sciences has recently discredited these methods, judging the Military Handbook (MIL-HDBK-217 and its progeny as invalid and inaccurate. This paper discusses the issues that arise with the use of handbook-based methods in commercial and military avionics applications. Alternative approaches to reliability design (and its demonstration are also discussed, including similarity analysis, testing, physics-of-failure, and data analytics for prognostics and systems health management.

  9. Reliability assessment of complex electromechanical systems under epistemic uncertainty

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  10. Reliable and valid assessment of Lichtenstein hernia repair skills.

    Science.gov (United States)

    Carlsen, C G; Lindorff-Larsen, K; Funch-Jensen, P; Lund, L; Charles, P; Konge, L

    2014-08-01

    Lichtenstein hernia repair is a common surgical procedure and one of the first procedures performed by a surgical trainee. However, formal assessment tools developed for this procedure are few and sparsely validated. The aim of this study was to determine the reliability and validity of an assessment tool designed to measure surgical skills in Lichtenstein hernia repair. Key issues were identified through a focus group interview. On this basis, an assessment tool with eight items was designed. Ten surgeons and surgical trainees were video recorded while performing Lichtenstein hernia repair, (four experts, three intermediates, and three novices). The videos were blindly and individually assessed by three raters (surgical consultants) using the assessment tool. Based on these assessments, validity and reliability were explored. The internal consistency of the items was high (Cronbach's alpha = 0.97). The inter-rater reliability was very good with an intra-class correlation coefficient (ICC) = 0.93. Generalizability analysis showed a coefficient above 0.8 even with one rater. The coefficient improved to 0.92 if three raters were used. One-way analysis of variance found a significant difference between the three groups which indicates construct validity, p fashion with the new procedure-specific assessment tool. We recommend this tool for future assessment of trainees performing Lichtenstein hernia repair to ensure that the objectives of competency-based surgical training are met.

  11. Human reliability analysis methods for probabilistic safety assessment

    International Nuclear Information System (INIS)

    Pyy, P.

    2000-11-01

    Human reliability analysis (HRA) of a probabilistic safety assessment (PSA) includes identifying human actions from safety point of view, modelling the most important of them in PSA models, and assessing their probabilities. As manifested by many incidents and studies, human actions may have both positive and negative effect on safety and economy. Human reliability analysis is one of the areas of probabilistic safety assessment (PSA) that has direct applications outside the nuclear industry. The thesis focuses upon developments in human reliability analysis methods and data. The aim is to support PSA by extending the applicability of HRA. The thesis consists of six publications and a summary. The summary includes general considerations and a discussion about human actions in the nuclear power plant (NPP) environment. A condensed discussion about the results of the attached publications is then given, including new development in methods and data. At the end of the summary part, the contribution of the publications to good practice in HRA is presented. In the publications, studies based on the collection of data on maintenance-related failures, simulator runs and expert judgement are presented in order to extend the human reliability analysis database. Furthermore, methodological frameworks are presented to perform a comprehensive HRA, including shutdown conditions, to study reliability of decision making, and to study the effects of wrong human actions. In the last publication, an interdisciplinary approach to analysing human decision making is presented. The publications also include practical applications of the presented methodological frameworks. (orig.)

  12. Validity and reliability of balance assessment software using the Nintendo Wii balance board: usability and validation.

    Science.gov (United States)

    Park, Dae-Sung; Lee, GyuChang

    2014-06-10

    A balance test provides important information such as the standard to judge an individual's functional recovery or make the prediction of falls. The development of a tool for a balance test that is inexpensive and widely available is needed, especially in clinical settings. The Wii Balance Board (WBB) is designed to test balance, but there is little software used in balance tests, and there are few studies on reliability and validity. Thus, we developed a balance assessment software using the Nintendo Wii Balance Board, investigated its reliability and validity, and compared it with a laboratory-grade force platform. Twenty healthy adults participated in our study. The participants participated in the test for inter-rater reliability, intra-rater reliability, and concurrent validity. The tests were performed with balance assessment software using the Nintendo Wii balance board and a laboratory-grade force platform. Data such as Center of Pressure (COP) path length and COP velocity were acquired from the assessment systems. The inter-rater reliability, the intra-rater reliability, and concurrent validity were analyzed by an intraclass correlation coefficient (ICC) value and a standard error of measurement (SEM). The inter-rater reliability (ICC: 0.89-0.79, SEM in path length: 7.14-1.90, SEM in velocity: 0.74-0.07), intra-rater reliability (ICC: 0.92-0.70, SEM in path length: 7.59-2.04, SEM in velocity: 0.80-0.07), and concurrent validity (ICC: 0.87-0.73, SEM in path length: 5.94-0.32, SEM in velocity: 0.62-0.08) were high in terms of COP path length and COP velocity. The balance assessment software incorporating the Nintendo Wii balance board was used in our study and was found to be a reliable assessment device. In clinical settings, the device can be remarkably inexpensive, portable, and convenient for the balance assessment.

  13. Reliable and Valid Assessment of Point-of-care Ultrasonography

    DEFF Research Database (Denmark)

    Todsen, Tobias; Tolsgaard, Martin Grønnebæk; Olsen, Beth Härstedt

    2015-01-01

    physicians' OSAUS scores with diagnostic accuracy. RESULTS: The generalizability coefficient was high (0.81) and a D-study demonstrated that 1 assessor and 5 cases would result in similar reliability. The construct validity of the OSAUS scale was supported by a significant difference in the mean scores......OBJECTIVE: To explore the reliability and validity of the Objective Structured Assessment of Ultrasound Skills (OSAUS) scale for point-of-care ultrasonography (POC US) performance. BACKGROUND: POC US is increasingly used by clinicians and is an essential part of the management of acute surgical...... conditions. However, the quality of performance is highly operator-dependent. Therefore, reliable and valid assessment of trainees' ultrasonography competence is needed to ensure patient safety. METHODS: Twenty-four physicians, representing novices, intermediates, and experts in POC US, scanned 4 different...

  14. Windfarm Generation Assessment for ReliabilityAnalysis of Power Systems

    DEFF Research Database (Denmark)

    Negra, Nicola Barberis; Holmstrøm, Ole; Bak-Jensen, Birgitte

    2007-01-01

    Due to the fast development of wind generation in the past ten years, increasing interest has been paid to techniques for assessing different aspects of power systems with a large amount of installed wind generation. One of these aspects concerns power system reliability. Windfarm modelling plays...

  15. Windfarm generation assessment for reliability analysis of power systems

    DEFF Research Database (Denmark)

    Negra, N.B.; Holmstrøm, O.; Bak-Jensen, B.

    2007-01-01

    Due to the fast development of wind generation in the past ten years, increasing interest has been paid to techniques for assessing different aspects of power systems with a large amount of installed wind generation. One of these aspects concerns power system reliability. Windfarm modelling plays...

  16. Methodology for reliability, economic and environmental assessment of wave energy

    International Nuclear Information System (INIS)

    Thorpe, T.W.; Muirhead, S.

    1994-01-01

    As part of the Preliminary Actions in Wave Energy R and D for DG XII's Joule programme, methodologies were developed to facilitate assessment of the reliability, economics and environmental impact of wave energy. This paper outlines these methodologies, their limitations and areas requiring further R and D. (author)

  17. Reliable and Valid Assessment of Clinical Bronchoscopy Performance

    DEFF Research Database (Denmark)

    Konge, Lars; Larsen, Klaus Richter; Clementsen, Paul

    2012-01-01

    : The interrater reliability was high, with Cronbach's a = 0.86. Assessment of 3 bronchoscopies by a single rater had a generalizability coefficient of 0.84. The correlation between experience and performance was good (Pearson correlation = 0.76). There were significant differences between the groups for all...

  18. Assessment of the Reliability of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C. R.

    This paper is based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges". It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....

  19. Assessment of reliability of Greulich and Pyle (gp) method for ...

    African Journals Online (AJOL)

    Background: Greulich and Pyle standards are the most widely used age estimation standards all over the world. The applicability of the Greulich and Pyle standards to populations which differ from their reference population is often questioned. This study aimed to assess the reliability of Greulich and Pyle (GP) method for ...

  20. Reliability of scored patient generated subjective global assessment ...

    African Journals Online (AJOL)

    Objective: Establish the reliability of the scored Patient Generated-Subjective Global Assessment (PG-SGA) in determining nutritional status among Antiretroviral Therapy (ART) naive HIV-infected adults. Methods: A descriptive, cross sectional study among outpatient medical clinics, in The AIDS Support Organization ...

  1. Qualification Users' Perceptions and Experiences of Assessment Reliability

    Science.gov (United States)

    Chamberlain, Suzanne

    2013-01-01

    This paper presents the findings of a study designed to explore qualification users' perceptions and experiences of reliability in the context of national assessment outcomes in England. The study consisted of 17 focus groups conducted across six sectors of qualification users: students, teachers, trainee teachers, job-seekers, employers and…

  2. Reliability of medical audit in quality assessment of medical care

    Directory of Open Access Journals (Sweden)

    Camacho Luiz Antonio Bastos

    1996-01-01

    Full Text Available Medical audit of hospital records has been a major component of quality of care assessment, although physician judgment is known to have low reliability. We estimated interrater agreement of quality assessment in a sample of patients with cardiac conditions admitted to an American teaching hospital. Physician-reviewers used structured review methods designed to improve quality assessment based on judgment. Chance-corrected agreement for the items considered more relevant to process and outcome of care ranged from low to moderate (0.2 to 0.6, depending on the review item and the principal diagnoses and procedures the patients underwent. Results from several studies seem to converge on this point. Comparisons among different settings should be made with caution, given the sensitivity of agreement measurements to prevalence rates. Reliability of review methods in their current stage could be improved by combining the assessment of two or more reviewers, and by emphasizing outcome-oriented events.

  3. Risk assessment and reliability for low level radioactive waste disposal

    International Nuclear Information System (INIS)

    Gregory, P.O.; Jones, G.A.

    1986-01-01

    The reliability of critical design features at low-level radioactive waste disposal facilities is a major concern in the licensing of these structures. To date, no systematic methodology has been adopted to evaluate the geotechnical reliability of Uranium Mill Tailings Remedial Action (UMTRA) disposal facilities currently being designed and/or constructed. This paper discusses and critiques the deterministic methods currently used to evaluate UMTRA reliability. Because deterministic methods may not be applicable in some cases because of the unusually long design life of UMTRA facilities, it is proposed that a probabilistic risk assessment-based methodology be used as a secondary method to aid in the evaluating of geotechnical reliability of critical items. Similar methodologies have proven successful in evaluating the reliability of a variety of conventional earth structures. In this paper, an ''acceptable'' level of risk for UMTRA facilities is developed, an evaluation method is presented, and two example applications of the proposed methodology are provided for a generic UMTRA disposal facility. The proposed technique is shown to be a simple method which might be used to aid in reliability evaluations on a selective basis. Finally, other possible applications and the limitations of the proposed methodology are discussed

  4. Observer reliability in assessing placental maturity by histology.

    OpenAIRE

    Khong, T Y; Staples, A; Bendon, R W; Chambers, H M; Gould, S J; Knowles, S; Shen-Schwarz, S

    1995-01-01

    AIMS--To evaluate the ability of five experienced perinatal pathologists to assess placental maturity reliably by histology. METHODS--Twenty four haematoxylin and eosin slides, six each from placentas of 27, 31, 35, and 39 weeks' gestation, were circulated to five pathologists on three separate occasions. The slides were labelled with the correct or incorrect gestational ages. RESULTS--The mean absolute error over all 360 readings was 2.72 weeks. Only 54% of the slides were assessed within tw...

  5. A common reference population from four European Holstein populations increases reliability of genomic predictions

    DEFF Research Database (Denmark)

    Lund, Mogens Sandø; de Ross, Sander PW; de Vries, Alfred G

    2011-01-01

    Background Size of the reference population and reliability of phenotypes are crucial factors influencing the reliability of genomic predictions. It is therefore useful to combine closely related populations. Increased accuracies of genomic predictions depend on the number of individuals added to...

  6. An approach for assessing ALWR passive safety system reliability

    International Nuclear Information System (INIS)

    Hake, T.M.

    1991-01-01

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

  7. Embedded mechatronic systems 1 analysis of failures, predictive reliability

    CERN Document Server

    El Hami, Abdelkhalak

    2015-01-01

    In operation, mechatronics embedded systems are stressed by loads of different causes: climate (temperature, humidity), vibration, electrical and electromagnetic. These stresses in components which induce failure mechanisms should be identified and modeled for better control. AUDACE is a collaborative project of the cluster Mov'eo that address issues specific to mechatronic reliability embedded systems. AUDACE means analyzing the causes of failure of components of mechatronic systems onboard. The goal of the project is to optimize the design of mechatronic devices by reliability. The projec

  8. Reliability of the Hazelbaker Assessment Tool for Lingual Frenulum Function

    Directory of Open Access Journals (Sweden)

    James Jennifer P

    2006-03-01

    Full Text Available Abstract Background About 3% of infants are born with a tongue-tie which may lead to breastfeeding problems such as ineffective latch, painful attachment or poor weight gain. The Hazelbaker Assessment Tool for Lingual Frenulum Function (HATLFF has been developed to give a quantitative assessment of the tongue-tie and recommendation about frenotomy (release of the frenulum. The aim of this study was to assess the inter-rater reliability of the HATLFF. Methods Fifty-eight infants referred to the Breastfeeding Education and Support Services (BESS at The Royal Women's Hospital for assessment of tongue-tie and 25 control infants were assessed by two clinicians independently. Results The Appearance items received kappas between about 0.4 to 0.6, which represents "moderate" reliability. The first three Function items (lateralization, lift and extension of tongue had kappa values over 0.65 which indicates "substantial" agreement. The four Function items relating to infant sucking (spread, cupping, peristalsis and snapback received low kappa values with insignificant p values. There was 96% agreement between the two assessors on the recommendation for frenotomy (kappa 0.92, excellent agreement. The study found that the Function Score can be more simply assessed using only the first three function items (ie not scoring the sucking items, with a cut-off of ≤4 for recommendation of frenotomy. Conclusion We found that the HATLFF has a high reliability in a study of infants with tongue-tie and control infants

  9. Engineering Design Handbook: Development Guide for Reliability. Part Three. Reliability Prediction

    Science.gov (United States)

    1976-01-01

    to t is pa(t)=l-qa(t) (10-6) This is the reliability of being closed, defined for this interval. 2 The probability that a contact viH be open...Monte Carlo simulation. Few people can know all about all available programs. Special- ists can assist in selecting a few from the avail- able many

  10. Methods to compute reliabilities for genomic predictions of feed intake

    Science.gov (United States)

    For new traits without historical reference data, cross-validation is often the preferred method to validate reliability (REL). Time truncation is less useful because few animals gain substantial REL after the truncation point. Accurate cross-validation requires separating genomic gain from pedigree...

  11. Nonspecialist Raters Can Provide Reliable Assessments of Procedural Skills

    DEFF Research Database (Denmark)

    Mahmood, Oria; Dagnæs, Julia; Bube, Sarah

    2018-01-01

    was significant (p Pearson's correlation of 0.77 for the nonspecialists and 0.75 for the specialists. The test-retest reliability showed the biggest difference between the 2 groups, 0.59 and 0.38 for the nonspecialist raters and the specialist raters, respectively (p ... was chosen as it is a simple procedural skill that is crucial to master in a resident urology program. RESULTS: The internal consistency of assessments was high, Cronbach's α = 0.93 and 0.95 for nonspecialist and specialist raters, respectively (p correlations). The interrater reliability...

  12. Quantitative reliability assessment for safety critical system software

    International Nuclear Information System (INIS)

    Chung, Dae Won; Kwon, Soon Man

    2005-01-01

    An essential issue in the replacement of the old analogue I and C to computer-based digital systems in nuclear power plants is the quantitative software reliability assessment. Software reliability models have been successfully applied to many industrial applications, but have the unfortunate drawback of requiring data from which one can formulate a model. Software which is developed for safety critical applications is frequently unable to produce such data for at least two reasons. First, the software is frequently one-of-a-kind, and second, it rarely fails. Safety critical software is normally expected to pass every unit test producing precious little failure data. The basic premise of the rare events approach is that well-tested software does not fail under normal routine and input signals, which means that failures must be triggered by unusual input data and computer states. The failure data found under the reasonable testing cases and testing time for these conditions should be considered for the quantitative reliability assessment. We will present the quantitative reliability assessment methodology of safety critical software for rare failure cases in this paper

  13. High reliability flow system - an assessment of pump reliability and optimisation of the number of pumps

    International Nuclear Information System (INIS)

    Butterfield, J.M.

    1981-01-01

    A system is considered where a number of pumps operate in parallel. Normally, all pumps operate, driven by main motors fed from the grid. Each pump has a pony motor fed from an individual battery supply. Each pony motor is normally running, but not engaged to the pump shaft. On demand, e.g. failure of grid supplies, each pony motor is designed to clutch-in automatically when the pump speed falls to a specified value. The probability of all the pony motors failing to clutch-in on demand must be demonstrated with 95% confidence to be less than 10 -8 per demand. This assessment considers how the required reliability of pony motor drives might be demonstrated in practice and the implications on choice of the number of pumps at the design stage. The assessment recognises that not only must the system prove to be extremely reliable, but that demonstration that reliability is adequate must be done during plant commissioning, with practical limits on the amount of testing performed. It is concluded that a minimum of eight pony motors should be provided, eight pumps each with one pony motor (preferred) or five pumps each with two independent pony motors. A minimum of two diverse pony motor systems should be provided. (author)

  14. Reliability-based assessment of polyethylene pipe creep lifetime

    International Nuclear Information System (INIS)

    Khelif, Rabia; Chateauneuf, Alaa; Chaoui, Kamel

    2007-01-01

    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

  15. Reliability-based assessment of polyethylene pipe creep lifetime

    Energy Technology Data Exchange (ETDEWEB)

    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: rabia.khelif@ifma.fr; Chateauneuf, Alaa [LGC-University Blaise Pascal, Campus des Cezeaux, BP 206, 63174 Aubiere Cedex (France)], E-mail: alaa.chateauneuf@polytech.univ-bpclermont.fr; Chaoui, Kamel [LR3MI, Departement de Genie Mecanique, Universite Badji Mokhtar, BP 12, Annaba 23000 (Algeria)], E-mail: chaoui@univ-annaba.org

    2007-12-15

    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.

  16. Predictions of models for environmental radiological assessment

    International Nuclear Information System (INIS)

    Peres, Sueli da Silva; Lauria, Dejanira da Costa; Mahler, Claudio Fernando

    2011-01-01

    In the field of environmental impact assessment, models are used for estimating source term, environmental dispersion and transfer of radionuclides, exposure pathway, radiation dose and the risk for human beings Although it is recognized that the specific information of local data are important to improve the quality of the dose assessment results, in fact obtaining it can be very difficult and expensive. Sources of uncertainties are numerous, among which we can cite: the subjectivity of modelers, exposure scenarios and pathways, used codes and general parameters. The various models available utilize different mathematical approaches with different complexities that can result in different predictions. Thus, for the same inputs different models can produce very different outputs. This paper presents briefly the main advances in the field of environmental radiological assessment that aim to improve the reliability of the models used in the assessment of environmental radiological impact. The intercomparison exercise of model supplied incompatible results for 137 Cs and 60 Co, enhancing the need for developing reference methodologies for environmental radiological assessment that allow to confront dose estimations in a common comparison base. The results of the intercomparison exercise are present briefly. (author)

  17. Reliability and Validity Assessment of a Linear Position Transducer

    Science.gov (United States)

    Garnacho-Castaño, Manuel V.; López-Lastra, Silvia; Maté-Muñoz, José L.

    2015-01-01

    The objectives of the study were to determine the validity and reliability of peak velocity (PV), average velocity (AV), peak power (PP) and average power (AP) measurements were made using a linear position transducer. Validity was assessed by comparing measurements simultaneously obtained using the Tendo Weightlifting Analyzer Systemi and T-Force Dynamic Measurement Systemr (Ergotech, Murcia, Spain) during two resistance exercises, bench press (BP) and full back squat (BS), performed by 71 trained male subjects. For the reliability study, a further 32 men completed both lifts using the Tendo Weightlifting Analyzer Systemz in two identical testing sessions one week apart (session 1 vs. session 2). Intraclass correlation coefficients (ICCs) indicating the validity of the Tendo Weightlifting Analyzer Systemi were high, with values ranging from 0.853 to 0.989. Systematic biases and random errors were low to moderate for almost all variables, being higher in the case of PP (bias ±157.56 W; error ±131.84 W). Proportional biases were identified for almost all variables. Test-retest reliability was strong with ICCs ranging from 0.922 to 0.988. Reliability results also showed minimal systematic biases and random errors, which were only significant for PP (bias -19.19 W; error ±67.57 W). Only PV recorded in the BS showed no significant proportional bias. The Tendo Weightlifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and estimating power in resistance exercises. The low biases and random errors observed here (mainly AV, AP) make this device a useful tool for monitoring resistance training. Key points This study determined the validity and reliability of peak velocity, average velocity, peak power and average power measurements made using a linear position transducer The Tendo Weight-lifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and power. PMID:25729300

  18. Human reliability: an evaluation of its understanding and prediction

    International Nuclear Information System (INIS)

    Joksimovich, V.

    1987-01-01

    This paper presents a viewpoint on the state-of-the-art in human reliability. The bases for this viewpoint are, by and large, research projects conducted by the NUS for the Electric Power Research Institute (EPRI) primarily with the objective of further enhancing the credibility of PRA methodology. The presentation is divided into the following key sections: Background and Overview, Methodology and Data Base with emphasis on the simulator data base

  19. Nanoscale deformation measurements for reliability assessment of material interfaces

    Science.gov (United States)

    Keller, Jürgen; Gollhardt, Astrid; Vogel, Dietmar; Michel, Bernd

    2006-03-01

    With the development and application of micro/nano electronic mechanical systems (MEMS, NEMS) for a variety of market segments new reliability issues will arise. The understanding of material interfaces is the key for a successful design for reliability of MEMS/NEMS and sensor systems. Furthermore in the field of BIOMEMS newly developed advanced materials and well known engineering materials are combined despite of fully developed reliability concepts for such devices and components. In addition the increasing interface-to volume ratio in highly integrated systems and nanoparticle filled materials are challenges for experimental reliability evaluation. New strategies for reliability assessment on the submicron scale are essential to fulfil the needs of future devices. In this paper a nanoscale resolution experimental method for the measurement of thermo-mechanical deformation at material interfaces is introduced. The determination of displacement fields is based on scanning probe microscopy (SPM) data. In-situ SPM scans of the analyzed object (i.e. material interface) are carried out at different thermo-mechanical load states. The obtained images are compared by grayscale cross correlation algorithms. This allows the tracking of local image patterns of the analyzed surface structure. The measurement results are full-field displacement fields with nanometer resolution. With the obtained data the mixed mode type of loading at material interfaces can be analyzed with highest resolution for future needs in micro system and nanotechnology.

  20. Nuclear power plant maintenance personnel reliability prediction (NPP/MPRP) effort at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Knee, H.E.; Haas, P.M.; Siegel, A.I.

    1981-01-01

    Human errors committed during maintenance activities are potentially a major contribution to the overall risk associated with the operation of a nuclear power plant (NPP). An NRC-sponsored program at Oak Ridge National Laboratory is attempting to develop a quantitative predictive technique to evaluate the contribution of maintenance errors to the overall NPP risk. The current work includes a survey of the requirements of potential users to ascertain the need for and content of the proposed quantitative model, plus an initial job/task analysis to determine the scope and applicability of various maintenance tasks. In addition, existing human reliability prediction models are being reviewed and assessed with respect to their applicability to NPP maintenance tasks. This paper discusses the status of the program and summarizes the results to date

  1. Mammography image assessment; validity and reliability of current scheme

    International Nuclear Information System (INIS)

    Hill, C.; Robinson, L.

    2015-01-01

    Mammographers currently score their own images according to criteria set out by Regional Quality Assurance. The criteria used are based on the ‘Perfect, Good, Moderate, Inadequate’ (PGMI) marking criteria established by the National Health Service Breast Screening Programme (NHSBSP) in their Quality Assurance Guidelines of 2006 1 . This document discusses the validity and reliability of the current mammography image assessment scheme. Commencing with a critical review of the literature this document sets out to highlight problems with the national approach to the use of marking schemes. The findings suggest that ‘PGMI’ scheme is flawed in terms of reliability and validity and is not universally applied across the UK. There also appear to be differences in schemes used by trainees and qualified mammographers. Initial recommendations are to be made in collaboration with colleagues within the National Health Service Breast Screening Programme (NHSBSP), Higher Education Centres, College of Radiographers and the Royal College of Radiologists in order to identify a mammography image appraisal scheme that is fit for purpose. - Highlights: • Currently no robust evidence based marking tools in use for the assessment of images in mammography. • Is current system valid, reliable and robust? • How can the current image assessment tool be improved? • Should students and qualified mammographers use the same tool? • What marking criteria are available for image assessment?

  2. Coding Scheme for Assessment of Students’ Explanations and Predictions

    Directory of Open Access Journals (Sweden)

    Mihael Gojkošek

    2017-04-01

    Full Text Available In the process of analyzing students’ explanations and predictions for interaction between brightness enhancement film and beam of white light, a need for objective and reliable assessment instrumentarose. Consequently, we developed a codingscheme that was mostly inspired by the rubrics for self-assessment of scientific abilities. In the paper we present the grading categories that were integrated in the coding scheme, and descriptions of criteria used for evaluation of students work. We report the results of reliability analysis of new assessment tool and present some examples of its application.

  3. The DYLAM approach to systems safety and reliability assessment

    International Nuclear Information System (INIS)

    Amendola, A.

    1988-01-01

    A survey of the principal features and applications of DYLAM (Dynamic Logical Analytical Methodology) is presented, whose basic principles can be summarized as follows: after a particular modelling of the component states, computerized heuristical procedures generate stochastic configurations of the system, whereas the resulting physical processes are simultaneously simulated to give account of the possible interactions between physics and states and, on the other hand, to search for system dangerous configurations and related probabilities. The association of probabilistic techniques for describing the states with physical equations for describing the process results in a very powerful tool for safety and reliability assessment of systems potentially subjected to dangerous incidental transients. A comprehensive picture of DYLAM capability for manifold applications can be obtained by the review of the study cases analyzed (LMFBR core accident, systems reliability assessment, accident simulation, man-machine interaction analysis, chemical reactors safety, etc.)

  4. Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual

    International Nuclear Information System (INIS)

    Gilbert, B.G.; Reece, W.J.; Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.

    1990-12-01

    The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal computer. NUCLARR can furnish the end user with data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented is a five-volume series of reports. Volume V: Data Manual provides a hard-copy representation of all data and related information available within the NUCLARR system software. This document is organized in three sections. Part 1 is the summary description, which presents an overview of the NUCLARR system and data processing procedures. Part 2 contains all data and information relevant to the human error probability (HEP) data side of NUCLARR. Data and information for the hardware component failure data (HCFD) side are presented in Part 3. 7 refs

  5. Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR)

    International Nuclear Information System (INIS)

    Gilbert, B.G.; Reece, W.J.; Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.

    1990-12-01

    The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal computer. NUCLARR can furnish the end user with data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. Volume 5: Data Manual provides a hard-copy representation of all data and related information available within the NUCLARR system software. This document is organized in three sections. Part 1 is the summary description, which presents an overview of the NUCLARR system and data processing procedures. Part 2 contains all data and information relevant to the human error probability (HEP) data side of NUCLARR. Data and information for the hardware component failure data (HCFD) side are presented in Part 3. 7 refs

  6. Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual

    International Nuclear Information System (INIS)

    Gilbert, B.G.; Reece, W.J.; Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.

    1990-12-01

    The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal computer. NUCLARR can furnish the end user with data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. Volume V: Data Manual provides a hard-copy representation of all data and related information available within the NUCLARR system software. This document is organized in three sections. Part 1 is the summary description, which presents an overview of the NUCLARR system and data processing procedures. Part 2 contains all data and information relevant to the human error probability (HEP) side of NUCLARR. Data and information for the hardware component failure data (HCFD) side are presented in Part 3. 7 refs., 1 fig

  7. Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Summary description

    International Nuclear Information System (INIS)

    Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.; Groh, M.R.; Gentillon, C.D.; Gilbert, B.G.; Reece, W.J.

    1990-05-01

    The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automate data base management system for storing and processing human error probability and hardware component failure rate data. The NUCLARR system software resides on an IBM (or compatible) personal microcomputer. NUCLARR can be accessed by the end user to furnish data suitable for input in human and/or hardware reliability analysis to support a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. This document Volume 1, of this series is the Summary Description, which presents an overview of the data management system, including a description of data collection, data qualification, data structure, and taxonomies. Programming activities, procedures for processing data, a user's guide, and hard copy data manual are presented in Volumes 2 through 5, NUREG/CR-4639

  8. Reliability Assessment for Low-cost Unmanned Aerial Vehicles

    Science.gov (United States)

    Freeman, Paul Michael

    Existing low-cost unmanned aerospace systems are unreliable, and engineers must blend reliability analysis with fault-tolerant control in novel ways. This dissertation introduces the University of Minnesota unmanned aerial vehicle flight research platform, a comprehensive simulation and flight test facility for reliability and fault-tolerance research. An industry-standard reliability assessment technique, the failure modes and effects analysis, is performed for an unmanned aircraft. Particular attention is afforded to the control surface and servo-actuation subsystem. Maintaining effector health is essential for safe flight; failures may lead to loss of control incidents. Failure likelihood, severity, and risk are qualitatively assessed for several effector failure modes. Design changes are recommended to improve aircraft reliability based on this analysis. Most notably, the control surfaces are split, providing independent actuation and dual-redundancy. The simulation models for control surface aerodynamic effects are updated to reflect the split surfaces using a first-principles geometric analysis. The failure modes and effects analysis is extended by using a high-fidelity nonlinear aircraft simulation. A trim state discovery is performed to identify the achievable steady, wings-level flight envelope of the healthy and damaged vehicle. Tolerance of elevator actuator failures is studied using familiar tools from linear systems analysis. This analysis reveals significant inherent performance limitations for candidate adaptive/reconfigurable control algorithms used for the vehicle. Moreover, it demonstrates how these tools can be applied in a design feedback loop to make safety-critical unmanned systems more reliable. Control surface impairments that do occur must be quickly and accurately detected. This dissertation also considers fault detection and identification for an unmanned aerial vehicle using model-based and model-free approaches and applies those

  9. Reliability prediction for structures under cyclic loads and recurring inspections

    Directory of Open Access Journals (Sweden)

    Alberto W. S. Mello Jr

    2009-06-01

    Full Text Available This work presents a methodology for determining the reliability of fracture control plans for structures subjected to cyclic loads. It considers the variability of the parameters involved in the problem, such as initial flaw and crack growth curve. The probability of detection (POD curve of the field non-destructive inspection method and the condition/environment are used as important factors for structural confidence. According to classical damage tolerance analysis (DTA, inspection intervals are based on detectable crack size and crack growth rate. However, all variables have uncertainties, which makes the final result totally stochastic. The material properties, flight loads, engineering tools and even the reliability of inspection methods are subject to uncertainties which can affect significantly the final maintenance schedule. The present methodology incorporates all the uncertainties in a simulation process, such as Monte Carlo, and establishes a relationship between the reliability of the overall maintenance program and the proposed inspection interval, forming a “cascade” chart. Due to the scatter, it also defines the confidence level of the “acceptable” risk. As an example, the damage tolerance analysis (DTA results are presented for the upper cockpit longeron splice bolt of the BAF upgraded F-5EM. In this case, two possibilities of inspection intervals were found: one that can be characterized as remote risk, with a probability of failure (integrity nonsuccess of 1 in 10 million, per flight hour; and other as extremely improbable, with a probability of nonsuccess of 1 in 1 billion, per flight hour, according to aviation standards. These two results are compared with the classical military airplane damage tolerance requirements.

  10. A model for assessing human cognitive reliability in PRA studies

    International Nuclear Information System (INIS)

    Hannaman, G.W.; Spurgin, A.J.; Lukic, Y.

    1985-01-01

    This paper summarizes the status of a research project sponsored by EPRI as part of the Probabilistic Risk Assessment (PRA) technology improvement program and conducted by NUS Corporation to develop a model of Human Cognitive Reliability (HCR). The model was synthesized from features identified in a review of existing models. The model development was based on the hypothesis that the key factors affecting crew response times are separable. The inputs to the model consist of key parameters the values of which can be determined by PRA analysts for each accident situation being assessed. The output is a set of curves which represent the probability of control room crew non-response as a function of time for different conditions affecting their performance. The non-response probability is then a contributor to the overall non-success of operating crews to achieve a functional objective identified in the PRA study. Simulator data and some small scale tests were utilized to illustrate the calibration of interim HCR model coefficients for different types of cognitive processing since the data were sparse. The model can potentially help PRA analysts make human reliability assessments more explicit. The model incorporates concepts from psychological models of human cognitive behavior, information from current collections of human reliability data sources and crew response time data from simulator training exercises

  11. Statistical reliability assessment of software-based systems

    International Nuclear Information System (INIS)

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

    1997-01-01

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

  12. Interrater reliability of videotaped observational gait-analysis assessments.

    Science.gov (United States)

    Eastlack, M E; Arvidson, J; Snyder-Mackler, L; Danoff, J V; McGarvey, C L

    1991-06-01

    The purpose of this study was to determine the interrater reliability of videotaped observational gait-analysis (VOGA) assessments. Fifty-four licensed physical therapists with varying amounts of clinical experience served as raters. Three patients with rheumatoid arthritis who demonstrated an abnormal gait pattern served as subjects for the videotape. The raters analyzed each patient's most severely involved knee during the four subphases of stance for the kinematic variables of knee flexion and genu valgum. Raters were asked to determine whether these variables were inadequate, normal, or excessive. The temporospatial variables analyzed throughout the entire gait cycle were cadence, step length, stride length, stance time, and step width. Generalized kappa coefficients ranged from .11 to .52. Intraclass correlation coefficients (2,1) and (3,1) were slightly higher. Our results indicate that physical therapists' VOGA assessments are only slightly to moderately reliable and that improved interrater reliability of the assessments of physical therapists utilizing this technique is needed. Our data suggest that there is a need for greater standardization of gait-analysis training.

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

    International Nuclear Information System (INIS)

    Lee, Seung Woo; Lee, Hwa Ki

    2008-01-01

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

  14. A reliability assessment methodology for the VHTR passive safety system

    International Nuclear Information System (INIS)

    Lee, Hyungsuk; Jae, Moosung

    2014-01-01

    The passive safety system of a VHTR (Very High Temperature Reactor), which has recently attracted worldwide attention, is currently being considered for the design of safety improvements for the next generation of nuclear power plants in Korea. The functionality of the passive system does not rely on an external source of an electrical support system, but on the intelligent use of natural phenomena. Its function involves an ultimate heat sink for a passive secondary auxiliary cooling system, especially during a station blackout such as the case of the Fukushima Daiichi reactor accidents. However, it is not easy to quantitatively evaluate the reliability of passive safety for the purpose of risk analysis, considering the existing active system failure since the classical reliability assessment method cannot be applied. Therefore, we present a new methodology to quantify the reliability based on reliability physics models. This evaluation framework is then applied to of the conceptually designed VHTR in Korea. The Response Surface Method (RSM) is also utilized for evaluating the uncertainty of the maximum temperature of nuclear fuel. The proposed method could contribute to evaluating accident sequence frequency and designing new innovative nuclear systems, such as the reactor cavity cooling system (RCCS) in VHTR to be designed and constructed in Korea.

  15. Predictable and reliable ECG monitoring over IEEE 802.11 WLANs within a hospital.

    Science.gov (United States)

    Park, Juyoung; Kang, Kyungtae

    2014-09-01

    Telecardiology provides mobility for patients who require constant electrocardiogram (ECG) monitoring. However, its safety is dependent on the predictability and robustness of data delivery, which must overcome errors in the wireless channel through which the ECG data are transmitted. We report here a framework that can be used to gauge the applicability of IEEE 802.11 wireless local area network (WLAN) technology to ECG monitoring systems in terms of delay constraints and transmission reliability. For this purpose, a medical-grade WLAN architecture achieved predictable delay through the combination of a medium access control mechanism based on the point coordination function provided by IEEE 802.11 and an error control scheme based on Reed-Solomon coding and block interleaving. The size of the jitter buffer needed was determined by this architecture to avoid service dropout caused by buffer underrun, through analysis of variations in transmission delay. Finally, we assessed this architecture in terms of service latency and reliability by modeling the transmission of uncompressed two-lead electrocardiogram data from the MIT-BIH Arrhythmia Database and highlight the applicability of this wireless technology to telecardiology.

  16. A pediatric FOUR score coma scale: interrater reliability and predictive validity.

    Science.gov (United States)

    Czaikowski, Brianna L; Liang, Hong; Stewart, C Todd

    2014-04-01

    The Full Outline of UnResponsiveness (FOUR) Score is a coma scale that consists of four components (eye and motor response, brainstem reflexes, and respiration). It was originally validated among the adult population and recently in a pediatric population. To enhance clinical assessment of pediatric intensive care unit patients, including those intubated and/or sedated, at our children's hospital, we modified the FOUR Score Scale for this population. This modified scale would provide many of the same advantages as the original, such as interrater reliability, simplicity, and elimination of the verbal component that is not compatible with the Glasgow Coma Scale (GCS), creating a more valuable neurological assessment tool for the nursing community. Our goal was to potentially provide greater information than the formally used GCS when assessing critically ill, neurologically impaired patients, including those sedated and/or intubated. Experienced pediatric intensive care unit nurses were trained as "expert raters." Two different nurses assessed each subject using the Pediatric FOUR Score Scale (PFSS), GCS, and Richmond Agitation Sedation Scale at three different time points. Data were compared with the Pediatric Cerebral Performance Category (PCPC) assessed by another nurse. Our hypothesis was that the PFSS and PCPC should highly correlate and the GCS and PCPC should correlate lower. Study results show that the PFSS is excellent for interrater reliability for trained nurse-rater pairs and prediction of poor outcome and in-hospital mortality, under various situations, but there were no statistically significant differences between the PFSS and the GCS. However, the PFSS does have the potential to provide greater neurological assessment in the intubated and/or sedated patient based on the outcomes of our study.

  17. Design and reliability of a didactic inphographic rubric assessment

    Directory of Open Access Journals (Sweden)

    Yunuen Ixchel GUZMÁN-CEDILLO

    2017-12-01

    Full Text Available The objective of this study is to describe design, validity process and reliability of a rubric assessment to evaluate didactic infographics quality. Participants were fifteen judges who participate in different moments of elaboration rubric process; it was made in three process phases: design, settings and reliability determination. Content validity was obtained by percentage agreement between 3 judges by component of the rubric; likewise a Krippendorff’s alpha were applied (a = .710 in pilot assessment with 5 infographics in order to set possible writings contradictions between components and criteria of performance. The intern consistence was determined by Cronbach’s alpha (? = .806 in 22 infographics gradation. An Intraclass correlation coefficient icc (a = .909 was applied to 6 judges qualifications also a Krippendorff’s alpha (a = .538 both of them in ordinal levels. The rubric is composed by 9 components, 3 performance levels, definitions of each component and assignments how to use the rubric. Results suggest the rubric is valid and reliable to grade quality of didactic infographic.

  18. Reliability and Validity Assessment of a Linear Position Transducer

    Directory of Open Access Journals (Sweden)

    Manuel V. Garnacho-Castaño

    2015-03-01

    Full Text Available The objectives of the study were to determine the validity and reliability of peak velocity (PV, average velocity (AV, peak power (PP and average power (AP measurements were made using a linear position transducer. Validity was assessed by comparing measurements simultaneously obtained using the Tendo Weightlifting Analyzer Systemi and T-Force Dynamic Measurement Systemr (Ergotech, Murcia, Spain during two resistance exercises, bench press (BP and full back squat (BS, performed by 71 trained male subjects. For the reliability study, a further 32 men completed both lifts using the Tendo Weightlifting Analyzer Systemz in two identical testing sessions one week apart (session 1 vs. session 2. Intraclass correlation coefficients (ICCs indicating the validity of the Tendo Weightlifting Analyzer Systemi were high, with values ranging from 0.853 to 0.989. Systematic biases and random errors were low to moderate for almost all variables, being higher in the case of PP (bias ±157.56 W; error ±131.84 W. Proportional biases were identified for almost all variables. Test-retest reliability was strong with ICCs ranging from 0.922 to 0.988. Reliability results also showed minimal systematic biases and random errors, which were only significant for PP (bias -19.19 W; error ±67.57 W. Only PV recorded in the BS showed no significant proportional bias. The Tendo Weightlifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and estimating power in resistance exercises. The low biases and random errors observed here (mainly AV, AP make this device a useful tool for monitoring resistance training.

  19. Investigating Postgraduate College Admission Interviews: Generalizability Theory Reliability and Incremental Predictive Validity

    Science.gov (United States)

    Arce-Ferrer, Alvaro J.; Castillo, Irene Borges

    2007-01-01

    The use of face-to-face interviews is controversial for college admissions decisions in light of the lack of availability of validity and reliability evidence for most college admission processes. This study investigated reliability and incremental predictive validity of a face-to-face postgraduate college admission interview with a sample of…

  20. Reliability Prediction Approaches For Domestic Intelligent Electric Energy Meter Based on IEC62380

    Science.gov (United States)

    Li, Ning; Tong, Guanghua; Yang, Jincheng; Sun, Guodong; Han, Dongjun; Wang, Guixian

    2018-01-01

    The reliability of intelligent electric energy meter is a crucial issue considering its large calve application and safety of national intelligent grid. This paper developed a procedure of reliability prediction for domestic intelligent electric energy meter according to IEC62380, especially to identify the determination of model parameters combining domestic working conditions. A case study was provided to show the effectiveness and validation.

  1. Improving risk assessment by defining consistent and reliable system scenarios

    Directory of Open Access Journals (Sweden)

    B. Mazzorana

    2009-02-01

    Full Text Available During the entire procedure of risk assessment for hydrologic hazards, the selection of consistent and reliable scenarios, constructed in a strictly systematic way, is fundamental for the quality and reproducibility of the results. However, subjective assumptions on relevant impact variables such as sediment transport intensity on the system loading side and weak point response mechanisms repeatedly cause biases in the results, and consequently affect transparency and required quality standards. Furthermore, the system response of mitigation measures to extreme event loadings represents another key variable in hazard assessment, as well as the integral risk management including intervention planning. Formative Scenario Analysis, as a supplement to conventional risk assessment methods, is a technique to construct well-defined sets of assumptions to gain insight into a specific case and the potential system behaviour. By two case studies, carried out (1 to analyse sediment transport dynamics in a torrent section equipped with control measures, and (2 to identify hazards induced by woody debris transport at hydraulic weak points, the applicability of the Formative Scenario Analysis technique is presented. It is argued that during scenario planning in general and with respect to integral risk management in particular, Formative Scenario Analysis allows for the development of reliable and reproducible scenarios in order to design more specifically an application framework for the sustainable assessment of natural hazards impact. The overall aim is to optimise the hazard mapping and zoning procedure by methodologically integrating quantitative and qualitative knowledge.

  2. Supporting change processes in design: Complexity, prediction and reliability

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, Claudia M. [Engineering Design Centre, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ (United Kingdom)]. E-mail: cme26@cam.ac.uk; Keller, Rene [Engineering Design Centre, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ (United Kingdom)]. E-mail: rk313@cam.ac.uk; Earl, Chris [Open University, Department of Design and Innovation, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)]. E-mail: C.F.Earl@open.ac.uk; Clarkson, P. John [Engineering Design Centre, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ (United Kingdom)]. E-mail: pjc10@cam.ac.uk

    2006-12-15

    Change to existing products is fundamental to design processes. New products are often designed through change or modification to existing products. Specific parts or subsystems are changed to similar ones whilst others are directly reused. Design by modification applies particularly to safety critical products where the reuse of existing working parts and subsystems can reduce cost and risk. However change is rarely a matter of just reusing or modifying parts. Changing one part can propagate through the entire design leading to costly rework or jeopardising the integrity of the whole product. This paper characterises product change based on studies in the aerospace and automotive industry and introduces tools to aid designers in understanding the potential effects of change. Two ways of supporting designers are described: probabilistic prediction of the effects of change and visualisation of change propagation through product connectivities. Change propagation has uncertainties which are amplified by the choices designers make in practice as they implement change. Change prediction and visualisation is discussed with reference to complexity in three areas of product development: the structural backcloth of connectivities in the existing product (and its processes), the descriptions of the product used in design and the actions taken to carry out changes.

  3. Evaluation of the Validity and Reliability of the Waterlow Pressure Ulcer Risk Assessment Scale.

    Science.gov (United States)

    Charalambous, Charalambos; Koulori, Agoritsa; Vasilopoulos, Aristidis; Roupa, Zoe

    2018-04-01

    Prevention is the ideal strategy to tackle the problem of pressure ulcers. Pressure ulcer risk assessment scales are one of the most pivotal measures applied to tackle the problem, much criticisms has been developed regarding the validity and reliability of these scales. To investigate the validity and reliability of the Waterlow pressure ulcer risk assessment scale. The methodology used is a narrative literature review, the bibliography was reviewed through Cinahl, Pubmed, EBSCO, Medline and Google scholar, 26 scientific articles where identified. The articles where chosen due to their direct correlation with the objective under study and their scientific relevance. The construct and face validity of the Waterlow appears adequate, but with regards to content validity changes in the category age and gender can be beneficial. The concurrent validity cannot be assessed. The predictive validity of the Waterlow is characterized by high specificity and low sensitivity. The inter-rater reliability has been demonstrated to be inadequate, this may be due to lack of clear definitions within the categories and differentiating level of knowledge between the users. Due to the limitations presented regarding the validity and reliability of the Waterlow pressure ulcer risk assessment scale, the scale should be used in conjunction with clinical assessment to provide optimum results.

  4. Evaluation of the Validity and Reliability of the Waterlow Pressure Ulcer Risk Assessment Scale

    Science.gov (United States)

    Charalambous, Charalambos; Koulori, Agoritsa; Vasilopoulos, Aristidis; Roupa, Zoe

    2018-01-01

    Introduction Prevention is the ideal strategy to tackle the problem of pressure ulcers. Pressure ulcer risk assessment scales are one of the most pivotal measures applied to tackle the problem, much criticisms has been developed regarding the validity and reliability of these scales. Objective To investigate the validity and reliability of the Waterlow pressure ulcer risk assessment scale. Method The methodology used is a narrative literature review, the bibliography was reviewed through Cinahl, Pubmed, EBSCO, Medline and Google scholar, 26 scientific articles where identified. The articles where chosen due to their direct correlation with the objective under study and their scientific relevance. Results The construct and face validity of the Waterlow appears adequate, but with regards to content validity changes in the category age and gender can be beneficial. The concurrent validity cannot be assessed. The predictive validity of the Waterlow is characterized by high specificity and low sensitivity. The inter-rater reliability has been demonstrated to be inadequate, this may be due to lack of clear definitions within the categories and differentiating level of knowledge between the users. Conclusion Due to the limitations presented regarding the validity and reliability of the Waterlow pressure ulcer risk assessment scale, the scale should be used in conjunction with clinical assessment to provide optimum results. PMID:29736104

  5. Reliability, compliance, and security in web-based course assessments

    Directory of Open Access Journals (Sweden)

    Scott Bonham

    2008-04-01

    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.

  6. Fast mission reliability prediction for Unmanned Aerial Vehicles

    International Nuclear Information System (INIS)

    Andrews, J.D.; Poole, J.; Chen, W.H.

    2013-01-01

    There is currently a significant interest in the use of autonomous vehicles in many industrial sectors. One such example is the ever increasing use of Unmanned Aerial Vehicles (UAVs), particularly in military operations. This enables dangerous missions to be accomplished without risk to a pilot. UAVs also have potential civil applications which would require their certification and the demonstration that they are able to respond safety to any potential circumstances. The aircraft would therefore need to be capable of responding safely to the occurrence of component failures, the emergence of threats such as other aircraft in the neighboring airspace, and changing weather conditions. The likelihood that an aircraft will successfully complete any mission can be predicted using phased mission analysis techniques. The predicted mission unreliability can be updated in response to changing circumstances. In the event that the likelihood of mission failure becomes too high then changes have to be made to the mission plan. If these calculations could be carried out fast enough then the quantification procedure could be used to establish an acceptable response to any new conditions. With a view to using the methodology in the context described above, this paper investigates ways in which phased mission analysis can be improved to reduce the calculation time. The methodology improves the processing capability for a UAV phased mission analysis by taking into account the specific characteristics of the fault tree structures which provide the causes of phase failure for a UAV mission. It also carries out as much of the quantification as possible in advance of the mission plan being formulated

  7. A generic method for assignment of reliability scores applied to solvent accessibility predictions

    Directory of Open Access Journals (Sweden)

    Nielsen Morten

    2009-07-01

    Full Text Available Abstract Background Estimation of the reliability of specific real value predictions is nontrivial and the efficacy of this is often questionable. It is important to know if you can trust a given prediction and therefore the best methods associate a prediction with a reliability score or index. For discrete qualitative predictions, the reliability is conventionally estimated as the difference between output scores of selected classes. Such an approach is not feasible for methods that predict a biological feature as a single real value rather than a classification. As a solution to this challenge, we have implemented a method that predicts the relative surface accessibility of an amino acid and simultaneously predicts the reliability for each prediction, in the form of a Z-score. Results An ensemble of artificial neural networks has been trained on a set of experimentally solved protein structures to predict the relative exposure of the amino acids. The method assigns a reliability score to each surface accessibility prediction as an inherent part of the training process. This is in contrast to the most commonly used procedures where reliabilities are obtained by post-processing the output. Conclusion The performance of the neural networks was evaluated on a commonly used set of sequences known as the CB513 set. An overall Pearson's correlation coefficient of 0.72 was obtained, which is comparable to the performance of the currently best public available method, Real-SPINE. Both methods associate a reliability score with the individual predictions. However, our implementation of reliability scores in the form of a Z-score is shown to be the more informative measure for discriminating good predictions from bad ones in the entire range from completely buried to fully exposed amino acids. This is evident when comparing the Pearson's correlation coefficient for the upper 20% of predictions sorted according to reliability. For this subset, values of 0

  8. Reliability of Volumetry and Perimetry to Assess Knee Volume.

    Science.gov (United States)

    Nunes, Guilherme S; Yamashitafuji, Igor; Wageck, Bruna; Teixeira, Guilherme Garcia; Karloh, Manuela; de Noronha, Marcos

    2016-08-24

    The treatment of edema after a knee injury is usually 1 of the main objectives during rehabilitation. To assess the success of treatment, 2 methods are commonly used in clinical practice: volumetry and perimetry. To investigate the intra- and interassessor reliability of volumetry and perimetry to assess knee volume. Cross-sectional. Laboratory. 45 healthy participants (26 women) with mean age of 22.4 ± 2.8 y. Knee volume was assessed by 3 assessors (A, B, and C) with 3 methods (lower-limb volumetry [LLV], knee volumetry [KV], and knee perimetry [KP]). Assessor A was the most-experienced assessor, and assessor C, the least experienced. LLV and KV were performed with participants in the orthostatic position, while KP was performed with participants in supine. For the interassessor analysis, the ICC2,1 was high (.82) for KV and very high for LLV (.99) and KP (.99). For the intra-assessor analysis, ICC2,1 ranged from moderate to high for KV (.69-.83) and was very high for LLV (.99) and KP (.97-.99). KV, LLV, and KP are reliable methods, both intra- and interassessor, to measure knee volume.

  9. Assessing Reliability of Cold Spray Sputter Targets in Photovoltaic Manufacturing

    Science.gov (United States)

    Hardikar, Kedar; Vlcek, Johannes; Bheemreddy, Venkata; Juliano, Daniel

    2017-10-01

    Cold spray has been used to manufacture more than 800 Cu-In-Ga (CIG) sputter targets for deposition of high-efficiency photovoltaic thin films. It is a preferred technique since it enables high deposit purity and transfer of non-equilibrium alloy states to the target material. In this work, an integrated approach to reliability assessment of such targets with deposit weight in excess of 50 lb. is undertaken, involving thermal-mechanical characterization of the material in as-deposited condition, characterization of the interface adhesion on cylindrical substrate in as-deposited condition, and developing means to assess target integrity under thermal-mechanical loads during the physical vapor deposition (PVD) sputtering process. Mechanical characterization of cold spray deposited CIG alloy is accomplished through the use of indentation testing and adaptation of Brazilian disk test. A custom lever test was developed to characterize adhesion along the cylindrical interface between the CIG deposit and cylindrical substrate, overcoming limitations of current standards. A cohesive zone model for crack initiation and propagation at the deposit interface is developed and validated using the lever test and later used to simulate the potential catastrophic target failure in the PVD process. It is shown that this approach enables reliability assessment of sputter targets and improves robustness.

  10. Method for assessing reliability of a network considering probabilistic safety assessment

    International Nuclear Information System (INIS)

    Cepin, M.

    2005-01-01

    A method for assessment of reliability of the network is developed, which uses the features of the fault tree analysis. The method is developed in a way that the increase of the network under consideration does not require significant increase of the model. The method is applied to small examples of network consisting of a small number of nodes and a small number of their connections. The results give the network reliability. They identify equipment, which is to be carefully maintained in order that the network reliability is not reduced, and equipment, which is a candidate for redundancy, as this would improve network reliability significantly. (author)

  11. Assessing high reliability via Bayesian approach and accelerated tests

    International Nuclear Information System (INIS)

    Erto, Pasquale; Giorgio, Massimiliano

    2002-01-01

    Sometimes the assessment of very high reliability levels is difficult for the following main reasons: - the high reliability level of each item makes it impossible to obtain, in a reasonably short time, a sufficient number of failures; - the high cost of the high reliability items to submit to life tests makes it unfeasible to collect enough data for 'classical' statistical analyses. In the above context, this paper presents a Bayesian solution to the problem of estimation of the parameters of the Weibull-inverse power law model, on the basis of a limited number (say six) of life tests, carried out at different stress levels, all higher than the normal one. The over-stressed (i.e. accelerated) tests allow the use of experimental data obtained in a reasonably short time. The Bayesian approach enables one to reduce the required number of failures adding to the failure information the available a priori engineers' knowledge. This engineers' involvement conforms to the most advanced management policy that aims at involving everyone's commitment in order to obtain total quality. A Monte Carlo study of the non-asymptotic properties of the proposed estimators and a comparison with the properties of maximum likelihood estimators closes the work

  12. Reliability assessment of distribution power systems including distributed generations

    International Nuclear Information System (INIS)

    Megdiche, M.

    2004-12-01

    Nowadays, power systems have reached a good level of reliability. Nevertheless, considering the modifications induced by the connections of small independent producers to distribution networks, there's a need to assess the reliability of these new systems. Distribution networks present several functional characteristics, highlighted by the qualitative study of the failures, as dispersed loads at several places, variable topology and some electrotechnical phenomena which must be taken into account to model the events that can occur. The adopted reliability calculations method is Monte Carlo simulations, the probabilistic method most powerful and most flexible to model complex operating of the distribution system. We devoted a first part on the case of a 20 kV feeder to which a cogeneration unit is connected. The method was applied to a software of stochastic Petri nets simulations. Then a second part related to the study of a low voltage power system supplied by dispersed generations. Here, the complexity of the events required to code the method in an environment of programming allowing the use of power system calculations (load flow, short-circuit, load shedding, management of units powers) in order to analyse the system state for each new event. (author)

  13. An approach for assessing ALWR passive safety system reliability

    International Nuclear Information System (INIS)

    Hake, T.M.

    1991-01-01

    Many advanced light water reactor designs incorporate passive rather than active safety features for front-line accident response. A method for evaluating the reliability of these passive systems in the context of probabilistic risk assessment has been developed at Sandia National Laboratories. This method addresses both the component (e.g. valve) failure aspect of passive system failure, and uncertainties in system success criteria arising from uncertainties in the system's underlying physical processes. These processes provide the system's driving force; examples are natural circulation and gravity-induced injection. This paper describes the method, and provides some preliminary results of application of the approach to the Westinghouse AP600 design

  14. Seismic reliability assessment methodology for CANDU concrete containment structures

    International Nuclear Information System (INIS)

    Stephens, M.J.; Nessim, M.A.; Hong, H.P.

    1995-05-01

    A study was undertaken to develop a reliability-based methodology for the assessment of existing CANDU concrete containment structures with respect to seismic loading. The focus of the study was on defining appropriate specified values and partial safety factors for earthquake loading and resistance parameters. Key issues addressed in the work were the identification of an approach to select design earthquake spectra that satisfy consistent safety levels, and the use of structure-specific data in the evaluation of structural resistance. (author). 23 refs., 9 tabs., 15 figs

  15. An overview of erosion corrosion models and reliability assessment for corrosion defects in piping system

    International Nuclear Information System (INIS)

    Srividya, A.; Suresh, H.N.; Verma, A.K.; Gopika, V.; Santosh

    2006-01-01

    Piping systems are part of passive structural elements in power plants. The analysis of the piping systems and their quantification in terms of failure probability is of utmost importance. The piping systems may fail due to various degradation mechanisms like thermal fatigue, erosion-corrosion, stress corrosion cracking and vibration fatigue. On examination of previous results, erosion corrosion was more prevalent and wall thinning is a time dependent phenomenon. The paper is intended to consolidate the work done by various investigators on erosion corrosion in estimating the erosion corrosion rate and reliability predictions. A comparison of various erosion corrosion models is made. The reliability predictions based on remaining strength of corroded pipelines by wall thinning is also attempted. Variables in the limit state functions are modelled using normal distributions and Reliability assessment is carried out using some of the existing failure pressure models. A steady state corrosion rate is assumed to estimate the corrosion defect and First Order Reliability Method (FORM) is used to find the probability of failure associated with corrosion defects over time using the software for Component Reliability evaluation (COMREL). (author)

  16. Reliable scar scoring system to assess photographs of burn patients.

    Science.gov (United States)

    Mecott, Gabriel A; Finnerty, Celeste C; Herndon, David N; Al-Mousawi, Ahmed M; Branski, Ludwik K; Hegde, Sachin; Kraft, Robert; Williams, Felicia N; Maldonado, Susana A; Rivero, Haidy G; Rodriguez-Escobar, Noe; Jeschke, Marc G

    2015-12-01

    Several scar-scoring scales exist to clinically monitor burn scar development and maturation. Although scoring scars through direct clinical examination is ideal, scars must sometimes be scored from photographs. No scar scale currently exists for the latter purpose. We modified a previously described scar scale (Yeong et al., J Burn Care Rehabil 1997) and tested the reliability of this new scale in assessing burn scars from photographs. The new scale consisted of three parameters as follows: scar height, surface appearance, and color mismatch. Each parameter was assigned a score of 1 (best) to 4 (worst), generating a total score of 3-12. Five physicians with burns training scored 120 representative photographs using the original and modified scales. Reliability was analyzed using coefficient of agreement, Cronbach alpha, intraclass correlation coefficient, variance, and coefficient of variance. Analysis of variance was performed using the Kruskal-Wallis test. Color mismatch and scar height scores were validated by analyzing actual height and color differences. The intraclass correlation coefficient, the coefficient of agreement, and Cronbach alpha were higher for the modified scale than those of the original scale. The original scale produced more variance than that in the modified scale. Subanalysis demonstrated that, for all categories, the modified scale had greater correlation and reliability than the original scale. The correlation between color mismatch scores and actual color differences was 0.84 and between scar height scores and actual height was 0.81. The modified scar scale is a simple, reliable, and useful scale for evaluating photographs of burn patients. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Reliable prediction of adsorption isotherms via genetic algorithm molecular simulation.

    Science.gov (United States)

    LoftiKatooli, L; Shahsavand, A

    2017-01-01

    Conventional molecular simulation techniques such as grand canonical Monte Carlo (GCMC) strictly rely on purely random search inside the simulation box for predicting the adsorption isotherms. This blind search is usually extremely time demanding for providing a faithful approximation of the real isotherm and in some cases may lead to non-optimal solutions. A novel approach is presented in this article which does not use any of the classical steps of the standard GCMC method, such as displacement, insertation, and removal. The new approach is based on the well-known genetic algorithm to find the optimal configuration for adsorption of any adsorbate on a structured adsorbent under prevailing pressure and temperature. The proposed approach considers the molecular simulation problem as a global optimization challenge. A detailed flow chart of our so-called genetic algorithm molecular simulation (GAMS) method is presented, which is entirely different from traditions molecular simulation approaches. Three real case studies (for adsorption of CO 2 and H 2 over various zeolites) are borrowed from literature to clearly illustrate the superior performances of the proposed method over the standard GCMC technique. For the present method, the average absolute values of percentage errors are around 11% (RHO-H 2 ), 5% (CHA-CO 2 ), and 16% (BEA-CO 2 ), while they were about 70%, 15%, and 40% for the standard GCMC technique, respectively.

  18. Reliability assessment of Passive Containment Cooling System of an Advanced Reactor using APSRA methodology

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mukesh, E-mail: mukeshd@barc.gov.in [Reactor Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Chakravarty, Aranyak [School of Nuclear Studies and Application, Jadavpur University, Kolkata 700032 (India); Nayak, A.K. [Reactor Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Prasad, Hari; Gopika, V. [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2014-10-15

    Highlights: • The paper deals with the reliability assessment of Passive Containment Cooling System of Advanced Heavy Water Reactor. • Assessment of Passive System ReliAbility (APSRA) methodology is used for reliability assessment. • Performance assessment of the PCCS is initially performed during a postulated design basis LOCA. • The parameters affecting the system performance are then identified and considered for further analysis. • The failure probabilities of the various components are assessed through a classical PSA treatment using generic data. - Abstract: Passive Systems are increasingly playing a prominent role in the advanced nuclear reactor systems and are being utilised in normal operations as well as safety systems of the reactors following an accident. The Passive Containment Cooling System (PCCS) is one of the several passive safety features in an Advanced Reactor (AHWR). In this paper, the APSRA methodology has been employed for reliability evaluation of the PCCS of AHWR. Performance assessment of the PCCS is initially performed during a postulated design basis LOCA using the best-estimate code RELAP5/Mod 3.2. The parameters affecting the system performance are then identified and considered for further analysis. Based on some pre-determined failure criterion, the failure surface for the system is predicted using the best-estimate code taking into account the deviations of the identified parameters from their nominal states as well as the model uncertainties inherent to the best estimate code. Root diagnosis is then carried out to determine the various failure causes, which occurs mainly due to malfunctioning of mechanical components. The failure probabilities of the various components are assessed through a classical PSA treatment using generic data. The reliability of the PCCS is then evaluated from the probability of availability of these components.

  19. Reliability assessment of Passive Containment Cooling System of an Advanced Reactor using APSRA methodology

    International Nuclear Information System (INIS)

    Kumar, Mukesh; Chakravarty, Aranyak; Nayak, A.K.; Prasad, Hari; Gopika, V.

    2014-01-01

    Highlights: • The paper deals with the reliability assessment of Passive Containment Cooling System of Advanced Heavy Water Reactor. • Assessment of Passive System ReliAbility (APSRA) methodology is used for reliability assessment. • Performance assessment of the PCCS is initially performed during a postulated design basis LOCA. • The parameters affecting the system performance are then identified and considered for further analysis. • The failure probabilities of the various components are assessed through a classical PSA treatment using generic data. - Abstract: Passive Systems are increasingly playing a prominent role in the advanced nuclear reactor systems and are being utilised in normal operations as well as safety systems of the reactors following an accident. The Passive Containment Cooling System (PCCS) is one of the several passive safety features in an Advanced Reactor (AHWR). In this paper, the APSRA methodology has been employed for reliability evaluation of the PCCS of AHWR. Performance assessment of the PCCS is initially performed during a postulated design basis LOCA using the best-estimate code RELAP5/Mod 3.2. The parameters affecting the system performance are then identified and considered for further analysis. Based on some pre-determined failure criterion, the failure surface for the system is predicted using the best-estimate code taking into account the deviations of the identified parameters from their nominal states as well as the model uncertainties inherent to the best estimate code. Root diagnosis is then carried out to determine the various failure causes, which occurs mainly due to malfunctioning of mechanical components. The failure probabilities of the various components are assessed through a classical PSA treatment using generic data. The reliability of the PCCS is then evaluated from the probability of availability of these components

  20. Reliability engineering

    International Nuclear Information System (INIS)

    Lee, Chi Woo; Kim, Sun Jin; Lee, Seung Woo; Jeong, Sang Yeong

    1993-08-01

    This book start what is reliability? such as origin of reliability problems, definition of reliability and reliability and use of reliability. It also deals with probability and calculation of reliability, reliability function and failure rate, probability distribution of reliability, assumption of MTBF, process of probability distribution, down time, maintainability and availability, break down maintenance and preventive maintenance design of reliability, design of reliability for prediction and statistics, reliability test, reliability data and design and management of reliability.

  1. Reliability assessment using Bayesian networks. Case study on quantative reliability estimation of a software-based motor protection relay

    International Nuclear Information System (INIS)

    Helminen, A.; Pulkkinen, U.

    2003-06-01

    In this report a quantitative reliability assessment of motor protection relay SPAM 150 C has been carried out. The assessment focuses to the methodological analysis of the quantitative reliability assessment using the software-based motor protection relay as a case study. The assessment method is based on Bayesian networks and tries to take the full advantage of the previous work done in a project called Programmable Automation System Safety Integrity assessment (PASSI). From the results and experiences achieved during the work it is justified to claim that the assessment method presented in the work enables a flexible use of qualitative and quantitative elements of reliability related evidence in a single reliability assessment. At the same time the assessment method is a concurrent way of reasoning one's beliefs and references about the reliability of the system. Full advantage of the assessment method is taken when using the method as a way to cultivate the information related to the reliability of software-based systems. The method can also be used as a communicational instrument in a licensing process of software-based systems. (orig.)

  2. Defect localization, characterization and reliability assessment in emerging photovoltaic devices.

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Benjamin Bing-Yeh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cruz-Campa, Jose Luis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Haase, Gad S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tangyunyong, Paiboon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Colr, Edward Isaac [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Okandan, Murat [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nielson, Gregory N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-04-01

    Microsystems-enabled photovoltaics (MEPV) can potentially meet increasing demands for light-weight, portable, photovoltaic solutions with high power density and efficiency. The study in this report examines failure analysis techniques to perform defect localization and evaluate MEPV modules. CMOS failure analysis techniques, including electroluminescence, light-induced voltage alteration, thermally-induced voltage alteration, optical beam induced current, and Seabeck effect imaging were successfully adapted to characterize MEPV modules. The relative advantages of each approach are reported. In addition, the effects of exposure to reverse bias and light stress are explored. MEPV was found to have good resistance to both kinds of stressors. The results form a basis for further development of failure analysis techniques for MEPVs of different materials systems or multijunction MEPVs. The incorporation of additional stress factors could be used to develop a reliability model to generate lifetime predictions for MEPVs as well as uncover opportunities for future design improvements.

  3. Application of nonparametric statistics to material strength/reliability assessment

    International Nuclear Information System (INIS)

    Arai, Taketoshi

    1992-01-01

    An advanced material technology requires data base on a wide variety of material behavior which need to be established experimentally. It may often happen that experiments are practically limited in terms of reproducibility or a range of test parameters. Statistical methods can be applied to understanding uncertainties in such a quantitative manner as required from the reliability point of view. Statistical assessment involves determinations of a most probable value and the maximum and/or minimum value as one-sided or two-sided confidence limit. A scatter of test data can be approximated by a theoretical distribution only if the goodness of fit satisfies a test criterion. Alternatively, nonparametric statistics (NPS) or distribution-free statistics can be applied. Mathematical procedures by NPS are well established for dealing with most reliability problems. They handle only order statistics of a sample. Mathematical formulas and some applications to engineering assessments are described. They include confidence limits of median, population coverage of sample, required minimum number of a sample, and confidence limits of fracture probability. These applications demonstrate that a nonparametric statistical estimation is useful in logical decision making in the case a large uncertainty exists. (author)

  4. Mechanical reliability assessment of optical fibres in Radiation environments

    International Nuclear Information System (INIS)

    Van Uffelen, M.

    2006-01-01

    After more than two decades of intensive research and even some pioneering applications in space, optical fibres are now finding their way in various radiation environments, including both fission and future fusion nuclear-power plants, and high-energy physics experiments. For example, next to distributed monitoring applications of large nuclear infrastructures, fibre-optics can also be used for data communications during maintenance operations in the reactor vessel of the future ITER (International Thermonuclear Experimental Reactor), or for plasma diagnostics applications during operation of the reactor. These maintenance and diagnostics tasks require the optical fibres to withstand extremely high doses of radiation, up to MGy dose levels and temperatures above 150 degrees Celsius. The reliability assessment of fibre-optic systems for their qualification in nuclear environments often requires to meet stringent radiation tolerance levels. The majority of (usually accelerated) radiation assessments have so far focused on optical properties, such as wavelength-dependent radiation induced attenuation and radio-luminescence. The relation of these radiation effects with the fabrication methods and other environmental parameters has been the subject of years of research. Only a few results are available on the long-term evolution of mechanical properties of irradiated optical fibres. As a first step towards understanding the long-term reliability of fibre-optic composite cables in hostile radiation environments, we therefore performed dynamic fatigue tests with different commercial-grade optical fibres, both multi-mode and single-mode types

  5. HitPredict version 4: comprehensive reliability scoring of physical protein-protein interactions from more than 100 species.

    Science.gov (United States)

    López, Yosvany; Nakai, Kenta; Patil, Ashwini

    2015-01-01

    HitPredict is a consolidated resource of experimentally identified, physical protein-protein interactions with confidence scores to indicate their reliability. The study of genes and their inter-relationships using methods such as network and pathway analysis requires high quality protein-protein interaction information. Extracting reliable interactions from most of the existing databases is challenging because they either contain only a subset of the available interactions, or a mixture of physical, genetic and predicted interactions. Automated integration of interactions is further complicated by varying levels of accuracy of database content and lack of adherence to standard formats. To address these issues, the latest version of HitPredict provides a manually curated dataset of 398 696 physical associations between 70 808 proteins from 105 species. Manual confirmation was used to resolve all issues encountered during data integration. For improved reliability assessment, this version combines a new score derived from the experimental information of the interactions with the original score based on the features of the interacting proteins. The combined interaction score performs better than either of the individual scores in HitPredict as well as the reliability score of another similar database. HitPredict provides a web interface to search proteins and visualize their interactions, and the data can be downloaded for offline analysis. Data usability has been enhanced by mapping protein identifiers across multiple reference databases. Thus, the latest version of HitPredict provides a significantly larger, more reliable and usable dataset of protein-protein interactions from several species for the study of gene groups. Database URL: http://hintdb.hgc.jp/htp. © The Author(s) 2015. Published by Oxford University Press.

  6. The Child Dental Control Assessment (CDCA) in youth: reliability, validity and cross-cultural differences.

    Science.gov (United States)

    Coolidge, T; Heima, M; Heaton, L J; Nakai, Y; Höskuldsson, O; Smith, T A; Weinstein, P; Milgrom, P

    2005-03-01

    The Child Dental Control Assessment (CDCA) measures children's preferred control strategies in the dental situation. Three studies are reported, assessing aspects of this instrument in youths from the USA, Japan and Australia. In particular, measurements were made as to the reliability and validity of this instrument in this age group in the three cultures, as well as comparing some results across cultures. These studies used a questionnaire design. Questionnaires (including the CDCA and other measures) were given to youths aged 11-15 in the three cultures. In one culture, youths received the questionnaire twice, to compute test-retest reliability. The measure's reliability and validity were similar to those of other measures. The CDCA behaves similarly to the Revised Iowa Dental Control Index (R-IDCI). Youths in all three cultures showed similar responses, although the Japanese were less likely to endorse items. Internal reliability of the scale ranged from 0.74 to 0.85. Test- retest reliability was 0.74. Participants in the High Desire/Low Predicted classification on the R-IDCI scored higher on the CDCA (t (73) = 2.9, p < .01). In the Japanese and Australian samples the correlation between CDCA and dental fear was 0.29-0.33 (p < .001). The Australian and USA samples scored significantly higher than the Japanese sample (overall F(2,1544) = 383.98, p < .001, followed by Tukey's HSD, p < .001). These results provide evidence for the reliability and validity of the CDCA in youth. It appears to measure the discrepancy between Desired and Predicted Control identified in the Revised Iowa Dental Control Index (R-IDCI). Responses of the youth in all three cultures were similar, indicating common dental control preferences for individuals of this age. However, consistent with cultural values, Japanese youth were less likely to endorse the control strategies. These results underline the need to develop culturally-specific, as well as situationally-specific control measures.

  7. Reliability of System Identification Techniques to Assess Standing Balance in Healthy Elderly.

    Directory of Open Access Journals (Sweden)

    Jantsje H Pasma

    Full Text Available System identification techniques have the potential to assess the contribution of the underlying systems involved in standing balance by applying well-known disturbances. We investigated the reliability of standing balance parameters obtained with multivariate closed loop system identification techniques.In twelve healthy elderly balance tests were performed twice a day during three days. Body sway was measured during two minutes of standing with eyes closed and the Balance test Room (BalRoom was used to apply four disturbances simultaneously: two sensory disturbances, to the proprioceptive and the visual system, and two mechanical disturbances applied at the leg and trunk segment. Using system identification techniques, sensitivity functions of the sensory disturbances and the neuromuscular controller were estimated. Based on the generalizability theory (G theory, systematic errors and sources of variability were assessed using linear mixed models and reliability was assessed by computing indexes of dependability (ID, standard error of measurement (SEM and minimal detectable change (MDC.A systematic error was found between the first and second trial in the sensitivity functions. No systematic error was found in the neuromuscular controller and body sway. The reliability of 15 of 25 parameters and body sway were moderate to excellent when the results of two trials on three days were averaged. To reach an excellent reliability on one day in 7 out of 25 parameters, it was predicted that at least seven trials must be averaged.This study shows that system identification techniques are a promising method to assess the underlying systems involved in standing balance in elderly. However, most of the parameters do not appear to be reliable unless a large number of trials are collected across multiple days. To reach an excellent reliability in one third of the parameters, a training session for participants is needed and at least seven trials of two

  8. Reliability assessment using degradation models: bayesian and classical approaches

    Directory of Open Access Journals (Sweden)

    Marta Afonso Freitas

    2010-04-01

    Full Text Available Traditionally, reliability assessment of devices has been based on (accelerated life tests. However, for highly reliable products, little information about reliability is provided by life tests in which few or no failures are typically observed. Since most failures arise from a degradation mechanism at work for which there are characteristics that degrade over time, one alternative is monitor the device for a period of time and assess its reliability from the changes in performance (degradation observed during that period. The goal of this article is to illustrate how degradation data can be modeled and analyzed by using "classical" and Bayesian approaches. Four methods of data analysis based on classical inference are presented. Next we show how Bayesian methods can also be used to provide a natural approach to analyzing degradation data. The approaches are applied to a real data set regarding train wheels degradation.Tradicionalmente, o acesso à confiabilidade de dispositivos tem sido baseado em testes de vida (acelerados. Entretanto, para produtos altamente confiáveis, pouca informação a respeito de sua confiabilidade é fornecida por testes de vida no quais poucas ou nenhumas falhas são observadas. Uma vez que boa parte das falhas é induzida por mecanismos de degradação, uma alternativa é monitorar o dispositivo por um período de tempo e acessar sua confiabilidade através das mudanças em desempenho (degradação observadas durante aquele período. O objetivo deste artigo é ilustrar como dados de degradação podem ser modelados e analisados utilizando-se abordagens "clássicas" e Bayesiana. Quatro métodos de análise de dados baseados em inferência clássica são apresentados. A seguir, mostramos como os métodos Bayesianos podem também ser aplicados para proporcionar uma abordagem natural à análise de dados de degradação. As abordagens são aplicadas a um banco de dados real relacionado à degradação de rodas de trens.

  9. Reliability worth assessment of radial systems with distributed generation

    OpenAIRE

    Bellart Llavall, Francesc Xavier

    2010-01-01

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

  10. The Irvine, Beatties, and Bresnahan (IBB) Forelimb Recovery Scale: An Assessment of Reliability and Validity

    Science.gov (United States)

    Irvine, Karen-Amanda; Ferguson, Adam R.; Mitchell, Kathleen D.; Beattie, Stephanie B.; Lin, Amity; Stuck, Ellen D.; Huie, J. Russell; Nielson, Jessica L.; Talbott, Jason F.; Inoue, Tomoo; Beattie, Michael S.; Bresnahan, Jacqueline C.

    2014-01-01

    The IBB scale is a recently developed forelimb scale for the assessment of fine control of the forelimb and digits after cervical spinal cord injury [SCI; (1)]. The present paper describes the assessment of inter-rater reliability and face, concurrent and construct validity of this scale following SCI. It demonstrates that the IBB is a reliable and valid scale that is sensitive to severity of SCI and to recovery over time. In addition, the IBB correlates with other outcome measures and is highly predictive of biological measures of tissue pathology. Multivariate analysis using principal component analysis (PCA) demonstrates that the IBB is highly predictive of the syndromic outcome after SCI (2), and is among the best predictors of bio-behavioral function, based on strong construct validity. Altogether, the data suggest that the IBB, especially in concert with other measures, is a reliable and valid tool for assessing neurological deficits in fine motor control of the distal forelimb, and represents a powerful addition to multivariate outcome batteries aimed at documenting recovery of function after cervical SCI in rats. PMID:25071704

  11. Assessment of microelectronics packaging for high temperature, high reliability applications

    Energy Technology Data Exchange (ETDEWEB)

    Uribe, F.

    1997-04-01

    This report details characterization and development activities in electronic packaging for high temperature applications. This project was conducted through a Department of Energy sponsored Cooperative Research and Development Agreement between Sandia National Laboratories and General Motors. Even though the target application of this collaborative effort is an automotive electronic throttle control system which would be located in the engine compartment, results of this work are directly applicable to Sandia`s national security mission. The component count associated with the throttle control dictates the use of high density packaging not offered by conventional surface mount. An enabling packaging technology was selected and thermal models defined which characterized the thermal and mechanical response of the throttle control module. These models were used to optimize thick film multichip module design, characterize the thermal signatures of the electronic components inside the module, and to determine the temperature field and resulting thermal stresses under conditions that may be encountered during the operational life of the throttle control module. Because the need to use unpackaged devices limits the level of testing that can be performed either at the wafer level or as individual dice, an approach to assure a high level of reliability of the unpackaged components was formulated. Component assembly and interconnect technologies were also evaluated and characterized for high temperature applications. Electrical, mechanical and chemical characterizations of enabling die and component attach technologies were performed. Additionally, studies were conducted to assess the performance and reliability of gold and aluminum wire bonding to thick film conductor inks. Kinetic models were developed and validated to estimate wire bond reliability.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-26

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

  13. Reliability of a semi-quantitative method for dermal exposure assessment (DREAM)

    NARCIS (Netherlands)

    Wendel de Joode, B. van; Hemmen, J.J. van; Meijster, T.; Major, V.; London, L.; Kromhout, H.

    2005-01-01

    Valid and reliable semi-quantitative dermal exposure assessment methods for epidemiological research and for occupational hygiene practice, applicable for different chemical agents, are practically nonexistent. The aim of this study was to assess the reliability of a recently developed

  14. Water resources assessment and prediction in China

    Directory of Open Access Journals (Sweden)

    W. Guangsheng

    2016-10-01

    Full Text Available Water resources assessment in China, can be classified into three groups: (i comprehensive water resources assessment, (ii annual water resources assessment, and (iii industrial project water resources assessment. Comprehensive water resources assessment is the conventional assessment where the frequency distribution of water resources in basins or provincial regions are analyzed. For the annual water resources assessment, water resources of the last year in basins or provincial regions are usually assessed. For the industrial project water resources assessment, the water resources situation before the construction of industrial project has to be assessed. To address the climate and environmental changes, hydrological and statistical models are widely applied for studies on assessing water resources changes. For the water resources prediction in China usually the monthly runoff prediction is used. In most low flow seasons, the flow recession curve is commonly used as prediction method. In the humid regions, the rainfall-runoff ensemble prediction (ESP has been widely applied for the monthly runoff prediction. The conditional probability method for the monthly runoff prediction was also applied to assess next month runoff probability under a fixed initial condition.

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

    International Nuclear Information System (INIS)

    Lofgren, E.V.

    1985-08-01

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

  16. Modified Tuck Jump Assessment: Reliability and Training of Raters

    Directory of Open Access Journals (Sweden)

    Craig A. Smith, Nicole J. Chimera, Monica R. Lininger, Meghan Warren

    2017-09-01

    Full Text Available We are writing with regard to “Intra- and inter-rater reliability of the modified tuck jump assessment,” by Fort-Vanmeerhaeghe et al. (2017 published in the Journal of Sports Science & Medicine. The authors reported on the reliability of the modified Tuck Jump Assessment (TJA. The purpose of the article was twofold: to introduce a new scoring methodology and to report on the interrater and intrarater reliability. The authors found the modified TJA to have excellent interrater reliability (ICC = 0.94, 95% CI = 0.88-0.97 and intrarater reliability (rater 1 ICC = 0.94, 95% CI = 0.88-0.9; rater 2 ICC = 0.96, 95% CI = 0.92-0.98 with experienced raters (n = 2 in a sample of 24 elite volleyball athletes. Overall, we found the study to be well conducted and valuable to the field of injury screening; however, the study did not adequately explain how the raters were trained in the modified TJA to improve consistency of scoring, or the modifications of the individual flaw “excessive contact noise at landing.” This information is necessary to improve the clinical utility of the TJA and direct future reliability studies. The TJA has been changed at least three times in the literature: from the initial introduction (Myer et al., 2006 to the most referenced and detailed protocol (Myer et al., 2011 to the publication under discussion (Fort-Vanmeerhaeghe et al., 2017. The initial test protocol was based upon clinical expertise and has evolved over time as new research emerged and problems arose with the original TJA. Initially, the TJA was scored on a visual analog scale (Myer et al., 2006, changed to a dichotomous scale (0 for no flaw or 1 for flaw present (Myer et al., 2011 and most recently modified using an ordinal scale (Fort-Vanmeerhaeghe et al., 2017. A significant disparity in the reported interrater and intrarater reliability arose with the dichotomously scored TJA, between those involved in the development of the TJA (Herrington et al., 2013

  17. Reliability assessment of passive isolation condenser system of AHWR using APSRA methodology

    International Nuclear Information System (INIS)

    Nayak, A.K.; Jain, Vikas; Gartia, M.R.; Prasad, Hari; Anthony, A.; Bhatia, S.K.; Sinha, R.K.

    2009-01-01

    In this paper, a methodology known as APSRA (Assessment of Passive System ReliAbility) is used for evaluation of reliability of passive isolation condenser system of the Indian Advanced Heavy Water Reactor (AHWR). As per the APSRA methodology, the passive system reliability evaluation is based on the failure probability of the system to perform the design basis function. The methodology first determines the operational characteristics of the system and the failure conditions based on a predetermined failure criterion. The parameters that could degrade the system performance are identified and considered for analysis. Different modes of failure and their cause are identified. The failure surface is predicted using a best estimate code considering deviations of the operating parameters from their nominal states, which affect the isolation condenser system performance. Once the failure surface of the system is predicted, the causes of failure are examined through root diagnosis, which occur mainly due to failure of mechanical components. Reliability of the system is evaluated through a classical PSA treatment based on the failure probability of the components using generic data

  18. Usage models in reliability assessment of software-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Haapanen, P.; Pulkkinen, U. [VTT Automation, Espoo (Finland); Korhonen, J. [VTT Electronics, Espoo (Finland)

    1997-04-01

    This volume in the OHA-project report series deals with the statistical reliability assessment of software based systems on the basis of dynamic test results and qualitative evidence from the system design process. Other reports to be published later on in the OHA-project report series will handle the diversity requirements in safety critical software-based systems, generation of test data from operational profiles and handling of programmable automation in plant PSA-studies. In this report the issues related to the statistical testing and especially automated test case generation are considered. The goal is to find an efficient method for building usage models for the generation of statistically significant set of test cases and to gather practical experiences from this method by applying it in a case study. The scope of the study also includes the tool support for the method, as the models may grow quite large and complex. (32 refs., 30 figs.).

  19. Analysis of dependent failures in risk assessment and reliability evaluation

    International Nuclear Information System (INIS)

    Fleming, K.N.; Mosleh, A.; Kelley, A.P. Jr.; Gas-Cooled Reactors Associates, La Jolla, CA)

    1983-01-01

    The ability to estimate the risk of potential reactor accidents is largely determined by the ability to analyze statistically dependent multiple failures. The importance of dependent failures has been indicated in recent probabilistic risk assessment (PRA) studies as well as in reports of reactor operating experiences. This article highlights the importance of several different types of dependent failures from the perspective of the risk and reliability analyst and provides references to the methods and data available for their analysis. In addition to describing the current state of the art, some recent advances, pitfalls, misconceptions, and limitations of some approaches to dependent failure analysis are addressed. A summary is included of the discourse on this subject, which is presented in the Institute of Electrical and Electronics Engineers/American Nuclear Society PRA Procedures Guide

  20. Usage models in reliability assessment of software-based systems

    International Nuclear Information System (INIS)

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

    1997-04-01

    This volume in the OHA-project report series deals with the statistical reliability assessment of software based systems on the basis of dynamic test results and qualitative evidence from the system design process. Other reports to be published later on in the OHA-project report series will handle the diversity requirements in safety critical software-based systems, generation of test data from operational profiles and handling of programmable automation in plant PSA-studies. In this report the issues related to the statistical testing and especially automated test case generation are considered. The goal is to find an efficient method for building usage models for the generation of statistically significant set of test cases and to gather practical experiences from this method by applying it in a case study. The scope of the study also includes the tool support for the method, as the models may grow quite large and complex. (32 refs., 30 figs.)

  1. Time-dependent reliability analysis and condition assessment of structures

    International Nuclear Information System (INIS)

    Ellingwood, B.R.

    1997-01-01

    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

  2. Quantification of human reliability in probabilistic safety assessment

    International Nuclear Information System (INIS)

    Hirschberg, S.; Dankg, Vinh N.

    1996-01-01

    Human performance may substantially influence the reliability and safety of complex technical systems. For this reason, Human Reliability Analysis (HRA) constitutes an important part of Probabilistic Safety Assessment (PSAs) or Quantitative Risk Analyses (QRAs). The results of these studies as well as analyses of past accidents and incidents clearly demonstrate the importance of human interactions. The contribution of human errors to the core damage frequency (CDF), as estimated in the Swedish nuclear PSAs, are between 15 and 88%. A survey of the FRAs in the Swiss PSAs shows that also for the Swiss nuclear power plants the estimated HE contributions are substantial (49% of the CDF due to internal events in the case of Beznau and 70% in the case of Muehleberg; for the total CDF, including external events, 25% respectively 20%). Similar results can be extracted from the PSAs carried out for French, German, and US plants. In PSAs or QRAs, the adequate treatment of the human interactions with the system is a key to the understanding of accident sequences and their relative importance to overall risk. The main objectives of HRA are: first, to ensure that the key human interactions are systematically identified and incorporated into the safety analysis in a traceable manner, and second, to quantify the probabilities of their success and failure. Adopting a structured and systematic approach to the assessment of human performance makes it possible to provide greater confidence that the safety and availability of human-machine systems is not unduly jeopardized by human performance problems. Section 2 discusses the different types of human interactions analysed in PSAs. More generally, the section presents how HRA fits in the overall safety analysis, that is, how the human interactions to be quantified are identified. Section 3 addresses the methods for quantification. Section 4 concludes the paper by presenting some recommendations and pointing out the limitations of the

  3. Assessment of Data Reliability of Wireless Sensor Network for Bioinformatics

    Directory of Open Access Journals (Sweden)

    Ting Dong

    2017-09-01

    Full Text Available As a focal point of biotechnology, bioinformatics integrates knowledge from biology, mathematics, physics, chemistry, computer science and information science. It generally deals with genome informatics, protein structure and drug design. However, the data or information thus acquired from the main areas of bioinformatics may not be effective. Some researchers combined bioinformatics with wireless sensor network (WSN into biosensor and other tools, and applied them to such areas as fermentation, environmental monitoring, food engineering, clinical medicine and military. In the combination, the WSN is used to collect data and information. The reliability of the WSN in bioinformatics is the prerequisite to effective utilization of information. It is greatly influenced by factors like quality, benefits, service, timeliness and stability, some of them are qualitative and some are quantitative. Hence, it is necessary to develop a method that can handle both qualitative and quantitative assessment of information. A viable option is the fuzzy linguistic method, especially 2-tuple linguistic model, which has been extensively used to cope with such issues. As a result, this paper introduces 2-tuple linguistic representation to assist experts in giving their opinions on different WSNs in bioinformatics that involve multiple factors. Moreover, the author proposes a novel way to determine attribute weights and uses the method to weigh the relative importance of different influencing factors which can be considered as attributes in the assessment of the WSN in bioinformatics. Finally, an illustrative example is given to provide a reasonable solution for the assessment.

  4. Human reliability assessment on the basis of operating experience

    International Nuclear Information System (INIS)

    Straeter, O.

    1997-01-01

    For development of methodology, available models for qualitative assessment of human errors (e.g. by Swain, Hacker, Rasmussen) and a variety of known systematic approaches for quantitiative assessment of inadequate human action (e.g. THERP, ASEP, HCR, SLIM) were taken as a basis to establish a job specification, which in turn was used for developing a method for acquisition, characterisation and evaluation of errors. This method encompasses the two processes of event analysis and event evaluation: The first step comprises analysis of events by analysis of information describing the conditions and scenarios of relevance to the inadequate human action examined. In addition to the description of process sequences, information is taken into account on possible conditions that may bring about failure. As an assessment of human reliability requires manifold approaches for evaluation, a connectionistic procedure was developed for evaluation of the compilation of events based on a debate about various approaches from the domain of artificial intelligence (AI). This procedure yields both qualitative and quantitative information through a homogenous approach. (orig./GL) [de

  5. On the reliability of predictions of geomechanical response - project Cosa in perspective

    International Nuclear Information System (INIS)

    Knowles, N.C.; Lowe, M.J.S.; Come, B.

    1990-01-01

    Project COSA (Comparison of computer codes for Salt) was set up by the CEC as international benchmark exercise to compare the reliability of predictions of thermo-mechanical response of HLW repositories in salt. The first phase (COSA I) was conducted between 1984-1986 and attention was directed at code verification issues. The second phase (COSA II), carried out in the period 1986-1988, addressed code validation and other issues. Specifically, a series of experimental heat and pressure tests carried out at the Asse Mine in Wast Germany were modelled and predictions of the thermo-mechanical behaviour were compared. Ten European organisations participated. A key feature of this exercise was that, as far as possible, the calculations were performed blind (i.e. without any knowledge of the observed behaviour) using the best information available a priori, to describe the physical situation to be modelled. Interest centred around the various constitutive models (of material behaviour) for rock-salt and the assumptions about the in situ state of stress. The paper gives an overview of the project, presents some broad conclusions and attempts to assess their significance. 17 refs., 6 figs., 2 tabs

  6. Optimization of reliability centered predictive maintenance scheme for inertial navigation system

    International Nuclear Information System (INIS)

    Jiang, Xiuhong; Duan, Fuhai; Tian, Heng; Wei, Xuedong

    2015-01-01

    The goal of this study is to propose a reliability centered predictive maintenance scheme for a complex structure Inertial Navigation System (INS) with several redundant components. GO Methodology is applied to build the INS reliability analysis model—GO chart. Components Remaining Useful Life (RUL) and system reliability are updated dynamically based on the combination of components lifetime distribution function, stress samples, and the system GO chart. Considering the redundant design in INS, maintenance time is based not only on components RUL, but also (and mainly) on the timing of when system reliability fails to meet the set threshold. The definition of components maintenance priority balances three factors: components importance to system, risk degree, and detection difficulty. Maintenance Priority Number (MPN) is introduced, which may provide quantitative maintenance priority results for all components. A maintenance unit time cost model is built based on components MPN, components RUL predictive model and maintenance intervals for the optimization of maintenance scope. The proposed scheme can be applied to serve as the reference for INS maintenance. Finally, three numerical examples prove the proposed predictive maintenance scheme is feasible and effective. - Highlights: • A dynamic PdM with a rolling horizon is proposed for INS with redundant components. • GO Methodology is applied to build the system reliability analysis model. • A concept of MPN is proposed to quantify the maintenance sequence of components. • An optimization model is built to select the optimal group of maintenance components. • The optimization goal is minimizing the cost of maintaining system reliability

  7. A generic Approach for Reliability Predictions considering non-uniformly Deterioration Behaviour

    International Nuclear Information System (INIS)

    Krause, Jakob; Kabitzsch, Klaus

    2012-01-01

    Predictive maintenance offers the possibility to prognosticate the remaining time until a maintenance action of a machine has to be scheduled. Unfortunately, current predictive maintenance solutions are only suitable for very specific use cases like reliability predictions based on vibration monitoring. Furthermore, they do not consider the fact that machines may deteriorate non-uniformly, depending on external influences (e.g., the work piece material in a milling machine or the changing fruit acid concentration in a bottling plant). In this paper two concepts for a generic predictive maintenance solution which also considers non-uniformly aging behaviour are introduced. The first concept is based on system models representing the health state of a technical system. As these models are usually statically (viz. without a timely dimension) their coefficients are determined periodically and the resulting time series is used as aging indicator. The second concept focuses on external influences (contexts) which change the behaviour of the previous mentioned aging indicators in order to increase the accuracy of reliability predictions. Therefore, context-depended time series models are determined and used to predict machine reliability. Both concepts were evaluated on data of an air ventilation system. Thereby, it could be shown that they are suitable to determine aging indicators in a generic way and to incorporate external influences in the reliability prediction. Through this, the quality of reliability predictions can be significantly increased. In reality this leads to a more accurate scheduling of maintenance actions. Furthermore, the generic character of the solutions makes the concepts suitable for a wide range of aging processes.

  8. Bearing Procurement Analysis Method by Total Cost of Ownership Analysis and Reliability Prediction

    Science.gov (United States)

    Trusaji, Wildan; Akbar, Muhammad; Sukoyo; Irianto, Dradjad

    2018-03-01

    In making bearing procurement analysis, price and its reliability must be considered as decision criteria, since price determines the direct cost as acquisition cost and reliability of bearing determine the indirect cost such as maintenance cost. Despite the indirect cost is hard to identify and measured, it has high contribution to overall cost that will be incurred. So, the indirect cost of reliability must be considered when making bearing procurement analysis. This paper tries to explain bearing evaluation method with the total cost of ownership analysis to consider price and maintenance cost as decision criteria. Furthermore, since there is a lack of failure data when bearing evaluation phase is conducted, reliability prediction method is used to predict bearing reliability from its dynamic load rating parameter. With this method, bearing with a higher price but has higher reliability is preferable for long-term planning. But for short-term planning the cheaper one but has lower reliability is preferable. This contextuality can give rise to conflict between stakeholders. Thus, the planning horizon needs to be agreed by all stakeholder before making a procurement decision.

  9. Impact of data source on travel time reliability assessment.

    Science.gov (United States)

    2014-08-01

    Travel time reliability measures are becoming an increasingly important input to the mobility and : congestion management studies. In the case of Maryland State Highway Administration, reliability : measures are key elements in the agencys Annual ...

  10. Portfolio assessment during medical internships: How to obtain a reliable and feasible assessment procedure?

    Science.gov (United States)

    Michels, Nele R M; Driessen, Erik W; Muijtjens, Arno M M; Van Gaal, Luc F; Bossaert, Leo L; De Winter, Benedicte Y

    2009-12-01

    A portfolio is used to mentor and assess students' clinical performance at the workplace. However, students and raters often perceive the portfolio as a time-consuming instrument. In this study, we investigated whether assessment during medical internship by a portfolio can combine reliability and feasibility. The domain-oriented reliability of 61 double-rated portfolios was measured, using a generalisability analysis with portfolio tasks and raters as sources of variation in measuring the performance of a student. We obtained reliability (Phi coefficient) of 0.87 with this internship portfolio containing 15 double-rated tasks. The generalisability analysis showed that an acceptable level of reliability (Phi = 0.80) was maintained when the amount of portfolio tasks was decreased to 13 or 9 using one and two raters, respectively. Our study shows that a portfolio can be a reliable method for the assessment of workplace learning. The possibility of reducing the amount of tasks or raters while maintaining a sufficient level of reliability suggests an increase in feasibility of portfolio use for both students and raters.

  11. An overview of the IAEA Safety Series on procedures for evaluating the reliability of predictions made by environmental transfer models

    International Nuclear Information System (INIS)

    Hoffman, F.W.; Hofer, E.

    1987-10-01

    The International Atomic Energy Agency is preparing a Safety Series publication on practical approaches for evaluating the reliability of the predictions made by environmental radiological assessment models. This publication identifies factors that affect the reliability of these predictions and discusses methods for quantifying uncertainty. Emphasis is placed on understanding the quantity of interest specified by the assessment question and distinguishing between stochastic variability and lack of knowledge about either the true value or the true distribution of values for quantity of interest. Among the many approaches discussed, model testing using independent data sets (model validation) is considered the best method for evaluating the accuracy in model predictions. Analytical and numerical methods for propagating the uncertainties in model parameters are presented and the strengths and weaknesses of model intercomparison exercises are also discussed. It is recognized that subjective judgment is employed throughout the entire modelling process, and quantitative reliability statements must be subjectively obtained when models are applied to different situations from those under which they have been tested. (6 refs.)

  12. Reliable prediction and determination of Norwegian lamb carcass composition and value

    International Nuclear Information System (INIS)

    Kongsro, Jørgen

    2008-01-01

    The main objective of this work was to study prediction and determination of Norwegian lamb carcass composition with different techniques spanning from subjective appraisal to computer-intensive methods. There is an increasing demand, both from farmers and processors of meats, for a more objective and reliable system for prediction of muscle (lean meat), fat, bone and value of a lamb carcass. When introducing new technologies for determination of lamb carcass composition, the reference method used for calibration must be precise and reliable. The precision and reliability of the current dissection reference for lamb carcass classification and grading has never been quantified. A poor reference method will not benefit even the most optimal system for prediction and determination of lamb carcasses. To help achieve reliable systems, the uncertainty or errors in the reference method and measuring systems needs to be quantified. Using proper calibration methods for the measuring systems, the uncertainty and modeling power can be determined for lamb carcasses. The results of the work presented in this thesis show that the current classification system using subjective appraisal (EUROP) is reliable; however the accuracy with respect to carcass composition, especially for lean meat or muscle and carcass value, is poor. The reference method used for determining lamb carcass composition with respect to lamb carcass classification and grading is precise and reliable for carcass composition. For the composition and yield of sub-primal cuts, the reliability varied, and was especially poor for the breast cut. Further attention is needed for jointing and cutting of sub-primals to achieve even higher precision and reliability of the reference method. As an alternative to butcher or manual dissection, Computer Tomography (CT) showed promising results with respect to prediction of lamb carcass composition. This method is nicknamed “virtual dissection”. By utilizing the

  13. Reliability algorithms applied to reinforced concrete structures durability assessment

    Directory of Open Access Journals (Sweden)

    C. G. Nogueira

    Full Text Available This paper addresses the analysis of probabilistic corrosion time initiation in reinforced concrete structures exposed to ions chloride penetration. Structural durability is an important criterion which must be evaluated in every type of structure, especially when these structures are constructed in aggressive atmospheres. Considering reinforced concrete members, chloride diffusion process is widely used to evaluate the durability. Therefore, at modelling this phenomenon, corrosion of reinforcements can be better estimated and prevented. These processes begin when a threshold level of chlorides concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in the literature, deterministic approaches fail to predict accurately the corrosion time initiation due to the inherently randomness observed in this process. In this regard, the durability can be more realistically represented using probabilistic approaches. A probabilistic analysis of ions chloride penetration is presented in this paper. The ions chloride penetration is simulated using the Fick's second law of diffusion. This law represents the chloride diffusion process, considering time dependent effects. The probability of failure is calculated using Monte Carlo simulation and the First Order Reliability Method (FORM with a direct coupling approach. Some examples are considered in order to study these phenomena and a simplified method is proposed to determine optimal values for concrete cover.

  14. Reliability of a single objective measure in assessing sleepiness.

    Science.gov (United States)

    Sunwoo, Bernie Y; Jackson, Nicholas; Maislin, Greg; Gurubhagavatula, Indira; George, Charles F; Pack, Allan I

    2012-01-01

    To evaluate reliability of single objective tests in assessing sleepiness. Subjects who completed polysomnography underwent a 4-nap multiple sleep latency test (MSLT) the following day. Prior to each nap opportunity on MSLT, subjects performed the psychomotor vigilance test (PVT) and divided attention driving task (DADT). Results of single versus multiple test administrations were compared using the intraclass correlation coefficient (ICC) and adjusted for test administration order effects to explore time of day effects. Measures were explored as continuous and binary (i.e., impaired or not impaired). Community-based sample evaluated at a tertiary, university-based sleep center. 372 adult commercial vehicle operators oversampled for increased obstructive sleep apnea risk. N/A. AS CONTINUOUS MEASURES, ICC WERE AS FOLLOWS: MSLT 0.45, PVT median response time 0.69, PVT number of lapses 0.51, 10-min DADT tracking error 0.87, 20-min DADT tracking error 0.90. Based on binary outcomes, ICC were: MSLT 0.63, PVT number of lapses 0.85, 10-min DADT 0.95, 20-min DADT 0.96. Statistically significant time of day effects were seen in both the MSLT and PVT but not the DADT. Correlation between ESS and different objective tests was strongest for MSLT, range [-0.270 to -0.195] and persisted across all time points. Single DADT and PVT administrations are reliable measures of sleepiness. A single MSLT administration can reasonably discriminate individuals with MSL < 8 minutes. These results support the use of a single administration of some objective tests of sleepiness when performed under controlled conditions in routine clinical care.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  16. Seismic reliability assessment of RC structures including soil–structure interaction using wavelet weighted least squares support vector machine

    International Nuclear Information System (INIS)

    Khatibinia, Mohsen; Javad Fadaee, Mohammad; Salajegheh, Javad; Salajegheh, Eysa

    2013-01-01

    An efficient metamodeling framework in conjunction with the Monte-Carlo Simulation (MCS) is introduced to reduce the computational cost in seismic reliability assessment of existing RC structures. In order to achieve this purpose, the metamodel is designed by combining weighted least squares support vector machine (WLS-SVM) and a wavelet kernel function, called wavelet weighted least squares support vector machine (WWLS-SVM). In this study, the seismic reliability assessment of existing RC structures with consideration of soil–structure interaction (SSI) effects is investigated in accordance with Performance-Based Design (PBD). This study aims to incorporate the acceptable performance levels of PBD into reliability theory for comparing the obtained annual probability of non-performance with the target values for each performance level. The MCS method as the most reliable method is utilized to estimate the annual probability of failure associated with a given performance level in this study. In WWLS-SVM-based MCS, the structural seismic responses are accurately predicted by WWLS-SVM for reducing the computational cost. To show the efficiency and robustness of the proposed metamodel, two RC structures are studied. Numerical results demonstrate the efficiency and computational advantages of the proposed metamodel for the seismic reliability assessment of structures. Furthermore, the consideration of the SSI effects in the seismic reliability assessment of existing RC structures is compared to the fixed base model. It shows which SSI has the significant influence on the seismic reliability assessment of structures.

  17. Clinical assessment of dysphagia in neurodegeneration (CADN): development, validity and reliability of a bedside tool for dysphagia assessment.

    Science.gov (United States)

    Vogel, Adam P; Rommel, Natalie; Sauer, Carina; Horger, Marius; Krumm, Patrick; Himmelbach, Marc; Synofzik, Matthis

    2017-06-01

    Screening assessments for dysphagia are essential in neurodegenerative disease. Yet there are no purpose-built tools to quantify swallowing deficits at bedside or in clinical trials. A quantifiable, brief, easy to administer assessment that measures the impact of dysphagia and predicts the presence or absence of aspiration is needed. The Clinical Assessment of Dysphagia in Neurodegeneration (CADN) was designed by a multidisciplinary team (neurology, neuropsychology, speech pathology) validated against strict methodological criteria in two neurodegenerative diseases, Parkinson's disease (PD) and degenerative ataxia (DA). CADN comprises two parts, an anamnesis (part one) and consumption (part two). Two-thirds of patients were assessed using reference tests, the SWAL-QOL symptoms subscale (part one) and videofluoroscopic assessment of swallowing (part two). CADN has 11 items and can be administered and scored in an average of 7 min. Test-retest reliability was established using correlation and Bland-Altman plots. 125 patients with a neurodegenerative disease were recruited; 60 PD and 65 DA. Validity was established using ROC graphs and correlations. CADN has sensitivity of 79 and 84% and specificity 71 and 69% for parts one and two, respectively. Significant correlations with disease severity were also observed (p dysphagia symptomatology and risk of aspiration. The CADN is a reliable, valid, brief, quantifiable, and easily deployed assessment of swallowing in neurodegenerative disease. It is thus ideally suited for both clinical bedside assessment and future multicentre clinical trials in neurodegenerative disease.

  18. Development of equipment reliability process using predictive technologies at Hamaoka Nuclear Power Station

    International Nuclear Information System (INIS)

    Taniguchi, Yuji; Sakuragi, Futoshi; Hamada, Seiichi

    2014-01-01

    Development of equipment reliability(ER) process, specifically for predictive maintenance (PdM) technologies integrated condition based maintenance (CBM) process, at Hamaoka Nuclear Power Station is introduced in this paper. Integration of predictive maintenance technologies such as vibration, oil analysis and thermo monitoring is more than important to establish strong maintenance strategies and to direct a specific technical development. In addition, a practical example of CBM is also presented to support the advantage of the idea. (author)

  19. Reliability analysis and prediction of mixed mode load using Markov Chain Model

    International Nuclear Information System (INIS)

    Nikabdullah, N.; Singh, S. S. K.; Alebrahim, R.; Azizi, M. A.; K, Elwaleed A.; Noorani, M. S. M.

    2014-01-01

    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

  20. Assimilation of satellite data to increase the reliability of the wave predictions in the Black Sea

    Science.gov (United States)

    Rusu, Liliana; Raileanu, Alina

    2015-04-01

    In order to improve the wave predictions provided in the Black Sea by a wave modelling system based on the SWAN (Simulating Waves Nearshore) spectral model, a technique for assimilating the satellite data has been implemented and evaluated. For this purpose, an approach based on the Optimal Interpolation method has been considered and its results are discussed in the present work. As a first step, SWAN model simulations have been carried out for a 5-year interval (2004-2008). The assimilation is made in terms of the significant wave height (Hs) for each 24 hours considering data coming from 4 satellites (ERS-2, JASON-1, JASON-2, GEOSAT Follow-On). Subsequently, data provided by two other satellites (ENVISAT and TOPEX) are used for validations. To assess the improvement brought in the model predictions by the assimilation scheme, a comparison has been performed between the model results with and without assimilation. The statistical parameters evaluated are: bias, mean absolute error, RMS error, scatter index, correlation coefficient and symmetric slope. The results show that the data assimilation procedure induces a significant improvement of the statistical parameters (lower values for bias, errors and scatter index and values closer to the unity of the correlation coefficient and for the symmetric slope). It was found also that an important factor in improving the wave predictions is represented by the value of the correlation length accounted for the Hs prediction errors (Lmax). Previous studies indicate for this length a value around four degrees in the vicinity of 45 degrees latitude (which corresponds also to the basin of the Black Sea). This value was first considered in the assimilation technique. On the other hand, taking also into account the fact that in the Black Sea the wind-sea waves are dominant, lower values for the parameter Lmax were tested as well and it seems that the most appropriate value for this parameter is between three and four degrees

  1. Reliability and Validity of Dual-Task Mobility Assessments in People with Chronic Stroke

    Science.gov (United States)

    Yang, Lei; He, Chengqi; Pang, Marco Yiu Chung

    2016-01-01

    . Conclusions The walking time derived from the various dual-task assessments generally demonstrated good to excellent reliability, making them potentially useful in clinical practice and future research endeavors. However, the usefulness of these measurements in predicting falls needs to be further explored. Relatively low reliability was shown in the cognitive outcomes and DTE, which may not be preferred measurements for assessing dual-task performance. PMID:26808662

  2. Human Reliability Analysis in Support of Risk Assessment for Positive Train Control

    Science.gov (United States)

    2003-06-01

    This report describes an approach to evaluating the reliability of human actions that are modeled in a probabilistic risk assessment : (PRA) of train control operations. This approach to human reliability analysis (HRA) has been applied in the case o...

  3. Reliability assessment of hydraulic cylinders considering service loads and flaw distribution

    International Nuclear Information System (INIS)

    Altamura, Alessandra; Beretta, Stefano

    2012-01-01

    Manufacturing process, service conditions and material properties are all necessary requirements to a good design of tubular mechanical components subjected to fatigue. The most common approach to this design is usually deterministic, where a fixed NDT threshold, related to flaw acceptance limit, is set. However many uncertainties are left aside, i.e. the failure probability related to the fatigue strength under applied loads. This paper addresses the reliability evaluation of tubular mechanical components carrying some flaws and subjected to cyclic internal pressure variation. The aim is comparing the probability of failure obtained under several assumptions. A reliability assessment model, based on a random variable approach, has been implemented by using the Monte Carlo method. The analysis of the results, from a case study based on load spectra measurements of hydraulic cylinders of earth moving machines, has consented to evaluate the most important factors influencing the fatigue life prediction of these components. Highlights: ► Reliability evaluation of tubular components subjected to variable internal pressure. ► The dispersion of the threshold controls the stochasticity of crack growth. ► A random variable model has been developed using Monte Carlo. ► Initial crack size and spectrum shape are key factors in reliability evaluation.

  4. Reliability-based Assessment of Fatigue Life for Bridges

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2012-01-01

    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...

  5. Construction of Valid and Reliable Test for Assessment of Students

    Science.gov (United States)

    Osadebe, P. U.

    2015-01-01

    The study was carried out to construct a valid and reliable test in Economics for secondary school students. Two research questions were drawn to guide the establishment of validity and reliability for the Economics Achievement Test (EAT). It is a multiple choice objective test of five options with 100 items. A sample of 1000 students was randomly…

  6. Assessment of power reliability and improvement potential by using ...

    African Journals Online (AJOL)

    This paper presents the use of smart reclosers for improving reliability of a distribution system of one of the major cities of Ethiopia. As frequent power interruptions are posing a huge problem to the life of the people and the economy, finding a solution to the problem is very essential. Electric reliability has affected social well ...

  7. Reliability assessment of Indian Point Unit 3 containment structure

    International Nuclear Information System (INIS)

    Kawakami, J.; Hwang, H.; Chang, M.T.; Reich, M.

    1984-01-01

    In the current design criteria, the load combinations specified for design of concrete containment structures are in the deterministic formats. However, by applying the probability-based reliability method developed by BNL to the concrete containment structures designed according to the criteria, it is possible to evaluate the reliability levels implied in the current design criteria. For this purpose, the reliability analysis is applied to the Indian Point Unit No. 3 containment. The details of the containment structure such as the geometries and the rebar arrangements, etc., are taken from the working drawings and the final safety analysis reports. Three kinds of loads are considered in the reliability analysis. They are, dead load (D), accidental pressure due to a large LOCA (P), and earthquake ground acceleration (E). Reliability analysis of the containment subjected to all combinations of loads is performed. Results are presented in this report

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

    DEFF Research Database (Denmark)

    Ramírez, José G. Rangel; Sørensen, John Dalsgaard

    2009-01-01

    Probabilistic methodologies represent an important tool to identify the suitable strategy to inspect and deal with the deterioration in structures such as offshore wind turbines (OWT). Reliability based methods such as Risk Based Inspection (RBI) planning may represent a proper methodology to opt...

  9. Reliability assessment of ballistic jump squats and bench throws.

    Science.gov (United States)

    Alemany, Joseph A; Pandorf, Clay E; Montain, Scott J; Castellani, John W; Tuckow, Alexander P; Nindl, Bradley C

    2005-02-01

    The purpose of this investigation was to determine the test-retest reliability and coefficient of variation of 2 novel physical performance tests. Ten healthy men (22.0 +/- 3.0 years, 87.0 +/- 8.0 kg, 20.0 +/- 5.0% body fat) performed 30 continuous and dynamic jump squats (JS) and bench throws (BT) on 4 separate occasions. The movements were performed under loaded conditions utilizing 30% of subject's predetermined 1 repetition maximum in the back squat and bench press. Mean power (MP; W), peak power (PP; W), mean velocity (MV; m.s(-1)), peak velocity (PV; m.s(-1)), and total work (TW; J) were assessed using a ballistic measurement system (Innervations Inc., Muncie, IN). Data were analyzed using repeated measures analysis of variance with Duncan's post hoc test when mean differences were p < or = 0.05. Intraclass correlation coefficient (ICC) and within-subject coefficient of variation (CV%) were also calculated. All values are presented as mean +/- SE. BT variables were statistically similar across the 4 sessions: MP (350.0 +/- 13.9 W), PP (431.4 +/- 18.5 W) MV (1.6 +/- 0.03 m.s(-1)), PV (2.0 +/- 0.03 m.s(-1)), and TW (199.1 +/- 7.2 J). For JS, session 3 PP (1,669.8 +/- 111.2 W) was significantly greater vs. sessions 1, 2, and 4 (1,601.2 +/- 58.4 W). Session 4 MP (1,403.2 +/- 88.6 W) and MV (1.9 +/- 0.1 m.s(-1)) for JS were significantly lower during sessions 1, 2, and 3 (MP: 1,479.4.5 +/- 44.8 W, MV: 2.0 +/- 0.05 m.s(-1)). TW (834.7 +/- 24.3 J) and PV (2.2 +/- 0.04 m.s(-1)) were statistically similar during all sessions for JS. The CVs ranged from 3.0 to 7.6% for the BT and 3.2 to 5.7% for the JS. ICCs for MP, PP, MV, PV, and TW were 0.92, 0.95, 0.94, 0.91, and 0.95, respectively, during BT. ICCs during JS for MP, PP, MV, PV, and TW were 0.96, 0.98, 0.94, 0.94, and 0.89, respectively. The results of the current study support the use of a 30 continuous and dynamic BT protocol as a reliable upper-body physical performance test, which can be administered with

  10. A generic method for assignment of reliability scores applied to solvent accessibility predictions

    DEFF Research Database (Denmark)

    Petersen, Bent; Petersen, Thomas Nordahl; Andersen, Pernille

    2009-01-01

    : The performance of the neural networks was evaluated on a commonly used set of sequences known as the CB513 set. An overall Pearson's correlation coefficient of 0.72 was obtained, which is comparable to the performance of the currently best public available method, Real-SPINE. Both methods associate a reliability...... comparing the Pearson's correlation coefficient for the upper 20% of predictions sorted according to reliability. For this subset, values of 0.79 and 0.74 are obtained using our and the compared method, respectively. This tendency is true for any selected subset....

  11. Network reliability assessment using a cellular automata approach

    International Nuclear Information System (INIS)

    Rocco S, Claudio M.; Moreno, Jose Ali

    2002-01-01

    Two cellular automata (CA) models that evaluate the s-t connectedness and shortest path in a network are presented. CA based algorithms enhance the performance of classical algorithms, since they allow a more reliable and straightforward parallel implementation resulting in a dynamic network evaluation, where changes in the connectivity and/or link costs can readily be incorporated avoiding recalculation from scratch. The paper also demonstrates how these algorithms can be applied for network reliability evaluation (based on Monte-Carlo approach) and for finding s-t path with maximal reliability

  12. A method to assign failure rates for piping reliability assessments

    International Nuclear Information System (INIS)

    Gamble, R.M.; Tagart, S.W. Jr.

    1991-01-01

    This paper reports on a simplified method that has been developed to assign failure rates that can be used in reliability and risk studies of piping. The method can be applied on a line-by-line basis by identifying line and location specific attributes that can lead to piping unreliability from in-service degradation mechanisms and random events. A survey of service experience for nuclear piping reliability also was performed. The data from this survey provides a basis for identifying in-service failure attributes and assigning failure rates for risk and reliability studies

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

    International Nuclear Information System (INIS)

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

    2005-04-01

    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 dominating condition, the use

  14. Structural Reliability Methods for Wind Power Converter System Component Reliability Assessment

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2012-01-01

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

  15. Reliability and Probabilistic Risk Assessment - How They Play Together

    Science.gov (United States)

    Safie, Fayssal M.; Stutts, Richard; Huang, Zhaofeng

    2015-01-01

    The objective of this presentation is to discuss the PRA process and the reliability engineering discipline, their differences and similarities, and how they are used as complimentary analyses to support design and flight decisions.

  16. Assessment of landslide distribution map reliability in Niigata prefecture - Japan using frequency ratio approach

    Science.gov (United States)

    Rahardianto, Trias; Saputra, Aditya; Gomez, Christopher

    2017-07-01

    Research on landslide susceptibility has evolved rapidly over the few last decades thanks to the availability of large databases. Landslide research used to be focused on discreet events but the usage of large inventory dataset has become a central pillar of landslide susceptibility, hazard, and risk assessment. Indeed, extracting meaningful information from the large database is now at the forth of geoscientific research, following the big-data research trend. Indeed, the more comprehensive information of the past landslide available in a particular area is, the better the produced map will be, in order to support the effective decision making, planning, and engineering practice. The landslide inventory data which is freely accessible online gives an opportunity for many researchers and decision makers to prevent casualties and economic loss caused by future landslides. This data is advantageous especially for areas with poor landslide historical data. Since the construction criteria of landslide inventory map and its quality evaluation remain poorly defined, the assessment of open source landslide inventory map reliability is required. The present contribution aims to assess the reliability of open-source landslide inventory data based on the particular topographical setting of the observed area in Niigata prefecture, Japan. Geographic Information System (GIS) platform and statistical approach are applied to analyze the data. Frequency ratio method is utilized to model and assess the landslide map. The outcomes of the generated model showed unsatisfactory results with AUC value of 0.603 indicate the low prediction accuracy and unreliability of the model.

  17. Complex proximal humerus fractures: Hertel's criteria reliability to predict head necrosis.

    Science.gov (United States)

    Campochiaro, G; Rebuzzi, M; Baudi, P; Catani, F

    2015-09-01

    The risk of post-traumatic humeral head avascular necrosis (AVN), regardless of the treatment, has a high reported incidence. In 2004, Hertel et al. stated that the most relevant predictors of ischemia after intracapsular fracture treated with osteosynthesis are the calcar length, medial hinge integrity and some specific fracture types. Based on Hertel's model, the purpose of this study is to evaluate both its reliability and weaknesses in our series of 267 fractures, assessing how the anatomical configuration of fracture, the quality of reduction and its maintenance were predictive of osteonecrosis development, and so to suggest a treatment choice algorithm. A retrospective study, level of evidence IV, was conducted to duly assess the radiographic features of 267 fractures treated from 2004 to 2010 following Hertel's criteria treated with open reduction and internal fixation by angular stability plates and screws. The average age was 65.2 years. The average follow-up was 28.3 ± 17.0 months. The percentage of AVN, the quality and maintenance of reduction obtained during surgery were evaluated. The AVN incidence was 3.7 %. No significant correlation with gender, age and fracture type was found. At the last follow-up X-ray, only 30 % presented all Hertel's good predictors in the AVN group, 4.7 % in the non-AVN group (p AVN group, it was poor in 50 %; while in the non-AVN group, it was poor in 3.4 % (p AVN were symptomatic, and three needed a second surgery. Hertel's criteria are important in the surgical planning, but they are not sufficient: an accurate evaluation of the calcar area fracture in three planes is required. All fractures involving calcar area should be studied with CT.

  18. Reliability: How much is it worth? Beyond its estimation or prediction, the (net) present value of reliability

    International Nuclear Information System (INIS)

    Saleh, J.H.; Marais, K.

    2006-01-01

    In this article, we link an engineering concept, reliability, to a financial and managerial concept, net present value, by exploring the impact of a system's reliability on its revenue generation capability. The framework here developed for non-repairable systems quantitatively captures the value of reliability from a financial standpoint. We show that traditional present value calculations of engineering systems do not account for system reliability, thus over-estimate a system's worth and can therefore lead to flawed investment decisions. It is therefore important to involve reliability engineers upfront before investment decisions are made in technical systems. In addition, the analyses here developed help designers identify the optimal level of reliability that maximizes a system's net present value-the financial value reliability provides to the system minus the cost to achieve this level of reliability. Although we recognize that there are numerous considerations driving the specification of an engineering system's reliability, we contend that the financial analysis of reliability here developed should be made available to decision-makers to support in part, or at least be factored into, the system reliability specification

  19. Assessment and Improving Methods of Reliability Indices in Bakhtar Regional Electricity Company

    Directory of Open Access Journals (Sweden)

    Saeed Shahrezaei

    2013-04-01

    Full Text Available Reliability of a system is the ability of a system to do prospected duties in future and the probability of desirable operation for doing predetermined duties. Power system elements failures data are the main data of reliability assessment in the network. Determining antiseptic parameters is the goal of reliability assessment by using system history data. These parameters help to recognize week points of the system. In other words, the goal of reliability assessment is operation improving and decreasing of the failures and power outages. This paper is developed to assess reliability indices of Bakhtar Regional Electricity Company up to 1393 and the improving methods and their effects on the reliability indices in this network. DIgSILENT Power Factory software is employed for simulation. Simulation results show the positive effect of improving methods in reliability indices of Bakhtar Regional Electricity Company.

  20. Reliability Prediction Of System And Component Of Process System Of RSG-GAS Reactor

    International Nuclear Information System (INIS)

    Sitorus Pane, Jupiter

    2001-01-01

    The older the reactor the higher the probability of the system and components suffer from loss of function or degradation. This phenomenon occurred because of wear, corrosion, and fatigue. Study on component reliability was generally performed deterministically and statistically. This paper would describe an analysis of using statistical method, i.e. regression Cox, in order to predict the reliability of the components and their environmental influence's factors. The result showed that the dynamics, non safety related, and mechanic components have higher risk of failure, whereas static, safety related, and electric have lower risk of failures. The relative risk value for variable of components dynamics, quality, dummy 1 and dummy 2 are of 1.54, 1.59, 1.50, and 0.83 compare to other components type with each variable. Component with the higher risk have lower reliability than lower one

  1. Reliability of self-reported childhood physical abuse by adults and factors predictive of inconsistent reporting.

    Science.gov (United States)

    McKinney, Christy M; Harris, T Robert; Caetano, Raul

    2009-01-01

    Little is known about the reliability of self-reported child physical abuse (CPA) or CPA reporting practices. We estimated reliability and prevalence of self-reported CPA and identified factors predictive of inconsistent CPA reporting among 2,256 participants using surveys administered in 1995 and 2000. Reliability of CPA was fair to moderate (kappa = 0.41). Using a positive report from either survey, the prevalence of moderate (61.8%) and severe (12.0%) CPA was higher than at either survey alone. Compared to consistent reporters of having experienced CPA, inconsistent reporters were less likely to be > or = 30 years old (vs. 18-29) or Black (vs. White) and more likely to have report one type (vs. > or = 2) of CPA. These findings may assist researchers conducting and interpreting studies of CPA.

  2. Reliability assessment of Port Harcourt 33/11kv Distribution System ...

    African Journals Online (AJOL)

    This makes reliability studies an important task besides all the other analyses required for assessing the system performance. The paper presents an analytical approach in the reliability assessment of the Port Harcourt 33/11kV power distribution system. The assessment was performed with the 2009 power outage data ...

  3. Validity and Reliability of Field-Based Measures for Assessing Movement Skill Competency in Lifelong Physical Activities: A Systematic Review.

    Science.gov (United States)

    Hulteen, Ryan M; Lander, Natalie J; Morgan, Philip J; Barnett, Lisa M; Robertson, Samuel J; Lubans, David R

    2015-10-01

    It has been suggested that young people should develop competence in a variety of 'lifelong physical activities' to ensure that they can be active across the lifespan. The primary aim of this systematic review is to report the methodological properties, validity, reliability, and test duration of field-based measures that assess movement skill competency in lifelong physical activities. A secondary aim was to clearly define those characteristics unique to lifelong physical activities. A search of four electronic databases (Scopus, SPORTDiscus, ProQuest, and PubMed) was conducted between June 2014 and April 2015 with no date restrictions. Studies addressing the validity and/or reliability of lifelong physical activity tests were reviewed. Included articles were required to assess lifelong physical activities using process-oriented measures, as well as report either one type of validity or reliability. Assessment criteria for methodological quality were adapted from a checklist used in a previous review of sport skill outcome assessments. Movement skill assessments for eight different lifelong physical activities (badminton, cycling, dance, golf, racquetball, resistance training, swimming, and tennis) in 17 studies were identified for inclusion. Methodological quality, validity, reliability, and test duration (time to assess a single participant), for each article were assessed. Moderate to excellent reliability results were found in 16 of 17 studies, with 71% reporting inter-rater reliability and 41% reporting intra-rater reliability. Only four studies in this review reported test-retest reliability. Ten studies reported validity results; content validity was cited in 41% of these studies. Construct validity was reported in 24% of studies, while criterion validity was only reported in 12% of studies. Numerous assessments for lifelong physical activities may exist, yet only assessments for eight lifelong physical activities were included in this review

  4. Predictive validity of measurements of clinical competence using the team objective structured bedside assessment (TOSBA): assessing the clinical competence of final year medical students.

    LENUS (Irish Health Repository)

    Meagher, Frances M

    2009-11-01

    The importance of valid and reliable assessment of student competence and performance is gaining increased recognition. Provision of valid patient-based formative assessment is an increasing challenge for clinical teachers in a busy hospital setting. A formative assessment tool that reliably predicts performance in the summative setting would be of value to both students and teachers.

  5. General Inattentiveness Is a Long-Term Reliable Trait Independently Predictive of Psychological Health

    DEFF Research Database (Denmark)

    Jensen, Christian Gaden; Niclasen, Janni; Vangkilde, Signe

    2016-01-01

    The Mindful Attention Awareness Scale (MAAS) measures perceived degree of inattentiveness in different contexts and is often used as a reversed indicator of mindfulness. MAAS is hypothesized to reflect a psychological trait or disposition when used outside attentional training contexts, but the l......The Mindful Attention Awareness Scale (MAAS) measures perceived degree of inattentiveness in different contexts and is often used as a reversed indicator of mindfulness. MAAS is hypothesized to reflect a psychological trait or disposition when used outside attentional training contexts......, but the long-term test-retest reliability of MAAS scores is virtually untested. It is unknown whether MAAS predicts psychological health after controlling for standardized socioeconomic status classifications. First, MAAS translated to Danish was validated psychometrically within a randomly invited healthy...... adult community sample (N = 490). Factor analysis confirmed that MAAS scores quantified a unifactorial construct of excellent composite reliability and consistent convergent validity. Structural equation modeling revealed that MAAS scores contributed independently to predicting psychological distress...

  6. Reliability of didactic grades to predict practical skills in an undergraduate dental college in Saudi Arabia.

    Science.gov (United States)

    Zawawi, Khalid H; Afify, Ahmed R; Yousef, Mohammed K; Othman, Hisham I; Al-Dharrab, Ayman A

    2015-01-01

    This longitudinal study was aimed to investigate the association between didactic grades and practical skills for dental students and whether didactic grades can reliability predict the dental students' practical performance. Didactic and practical grades for graduates from the Faculty of Dentistry, King Abdulaziz University, between the years 2009 and 2011 were collected. Four courses were selected: Dental Anatomy, Operative Dentistry, Prosthodontics, and Orthodontics. Pearson product-moment correlation analyses between didactic and practical scores were conducted. There was only a significant correlation between didactic and practical scores for the Dental Anatomy course (Pdidactic scores (Pdidactic and practical scores for all subjects. Based on the findings of this study, the relationship between didactic grades and practical performance is course specific. Didactic grades do not reliably predict the students' practical skills. Measuring practical performances should be independent from didactic grading.

  7. A dynamic particle filter-support vector regression method for reliability prediction

    International Nuclear Information System (INIS)

    Wei, Zhao; Tao, Tao; ZhuoShu, Ding; Zio, Enrico

    2013-01-01

    Support vector regression (SVR) has been applied to time series prediction and some works have demonstrated the feasibility of its use to forecast system reliability. For accuracy of reliability forecasting, the selection of SVR's parameters is important. The existing research works on SVR's parameters selection divide the example dataset into training and test subsets, and tune the parameters on the training data. However, these fixed parameters can lead to poor prediction capabilities if the data of the test subset differ significantly from those of training. Differently, the novel method proposed in this paper uses particle filtering to estimate the SVR model parameters according to the whole measurement sequence up to the last observation instance. By treating the SVR training model as the observation equation of a particle filter, our method allows updating the SVR model parameters dynamically when a new observation comes. Because of the adaptability of the parameters to dynamic data pattern, the new PF–SVR method has superior prediction performance over that of standard SVR. Four application results show that PF–SVR is more robust than SVR to the decrease of the number of training data and the change of initial SVR parameter values. Also, even if there are trends in the test data different from those in the training data, the method can capture the changes, correct the SVR parameters and obtain good predictions. -- Highlights: •A dynamic PF–SVR method is proposed to predict the system reliability. •The method can adjust the SVR parameters according to the change of data. •The method is robust to the size of training data and initial parameter values. •Some cases based on both artificial and real data are studied. •PF–SVR shows superior prediction performance over standard SVR

  8. Reliability of the Bulb Dynamometer for Assessing Grip Strength

    Directory of Open Access Journals (Sweden)

    Colleen Maher

    2018-04-01

    Full Text Available Background: Hand function is an overall indicator of health and is often measured using grip strength. Handheld dynamometry is the most common method of measuring grip strength. The purpose of this study was to determine the inter-rater and test-retest reliability, the reliability of one trial versus three trials, and the preliminary norms for a young adult population using the Baseline® Pneumatic Squeeze Bulb Dynamometer (30 psi. Methods: This study used a one-group methodological design. One hundred and three healthy adults (30 males and 73 females were recruited. Six measurements were collected for each hand per participant. The data was analyzed using Intraclass Correlation Coefficients (ICC two-way effects model (2,2 and paired-samples t-tests. Results: The ICC for inter-rater reliability ranged from 0.955 to 0.977. Conclusion: The results of this study suggest that the bulb dynamometer is a reliable tool to measure grip strength and should be further explored for reliable and valid use in diverse populations and as an alternative to the Jamar dynamometer.

  9. Discrete Address Beacon System (DABS) Software System Reliability Modeling and Prediction.

    Science.gov (United States)

    1981-06-01

    Service ( ATARS ) module because of its interim status. Reliability prediction models for software modules were derived and then verified by matching...System (A’iCR3BS) and thus can be introduced gradually and economically without ma jor olper- ational or procedural change. Since DABS uses monopulse...lineanaly- sis tools or are ured during maintenance or pre-initialization were not modeled because they are not part of the mission software. The ATARS

  10. Reliability, Validity, and Predictive Utility of the 25-Item Criminogenic Cognitions Scale (CCS)

    OpenAIRE

    Tangney, June Price; Stuewig, Jeffrey; Furukawa, Emi; Kopelovich, Sarah; Meyer, Patrick; Cosby, Brandon

    2012-01-01

    Theory, research, and clinical reports suggest that moral cognitions play a role in initiating and sustaining criminal behavior. The 25 item Criminogenic Cognitions Scale (CCS) was designed to tap 5 dimensions: Notions of entitlement; Failure to Accept Responsibility; Short-Term Orientation; Insensitivity to Impact of Crime; and Negative Attitudes Toward Authority. Results from 552 jail inmates support the reliability, validity, and predictive utility of the measure. The CCS was linked to cri...

  11. A summary of methods of predicting reliability life of nuclear equipment with small samples

    International Nuclear Information System (INIS)

    Liao Weixian

    2000-03-01

    Some of nuclear equipment are manufactured in small batch, e.g., 1-3 sets. Their service life may be very difficult to determine experimentally in view of economy and technology. The method combining theoretical analysis with material tests to predict the life of equipment is put forward, based on that equipment consists of parts or elements which are made of different materials. The whole life of an equipment part consists of the crack forming life (i.e., the fatigue life or the damage accumulation life) and the crack extension life. Methods of predicting machine life has systematically summarized with the emphasis on those which use theoretical analysis to substitute large scale prototype experiments. Meanwhile, methods and steps of predicting reliability life have been described by taking into consideration of randomness of various variables and parameters in engineering. Finally, the latest advance and trends of machine life prediction are discussed

  12. An application of characteristic function in order to predict reliability and lifetime of aeronautical hardware

    Energy Technology Data Exchange (ETDEWEB)

    Żurek, Józef; Kaleta, Ryszard; Zieja, Mariusz [Air Force Institute of Technology ul. Księcia Bolesława 6 01-494 Warsaw (Poland)

    2016-06-08

    The forecasting of reliability and life of aeronautical hardware requires recognition of many and various destructive processes that deteriorate the health/maintenance status thereof. The aging of technical components of aircraft as an armament system proves of outstanding significance to reliability and safety of the whole system. The aging process is usually induced by many and various factors, just to mention mechanical, biological, climatic, or chemical ones. The aging is an irreversible process and considerably affects (i.e. reduces) reliability and lifetime of aeronautical equipment. Application of the characteristic function of the aging process is suggested to predict reliability and lifetime of aeronautical hardware. An increment in values of diagnostic parameters is introduced to formulate then, using the characteristic function and after some rearrangements, the partial differential equation. An analytical dependence for the characteristic function of the aging process is a solution to this equation. With the inverse transformation applied, the density function of the aging of aeronautical hardware is found. Having found the density function, one can determine the aeronautical equipment’s reliability and lifetime. The in-service collected or the life tests delivered data are used to attain this goal. Coefficients in this relationship are found using the likelihood function.

  13. An application of characteristic function in order to predict reliability and lifetime of aeronautical hardware

    International Nuclear Information System (INIS)

    Żurek, Józef; Kaleta, Ryszard; Zieja, Mariusz

    2016-01-01

    The forecasting of reliability and life of aeronautical hardware requires recognition of many and various destructive processes that deteriorate the health/maintenance status thereof. The aging of technical components of aircraft as an armament system proves of outstanding significance to reliability and safety of the whole system. The aging process is usually induced by many and various factors, just to mention mechanical, biological, climatic, or chemical ones. The aging is an irreversible process and considerably affects (i.e. reduces) reliability and lifetime of aeronautical equipment. Application of the characteristic function of the aging process is suggested to predict reliability and lifetime of aeronautical hardware. An increment in values of diagnostic parameters is introduced to formulate then, using the characteristic function and after some rearrangements, the partial differential equation. An analytical dependence for the characteristic function of the aging process is a solution to this equation. With the inverse transformation applied, the density function of the aging of aeronautical hardware is found. Having found the density function, one can determine the aeronautical equipment’s reliability and lifetime. The in-service collected or the life tests delivered data are used to attain this goal. Coefficients in this relationship are found using the likelihood function.

  14. Failure and reliability prediction by support vector machines regression of time series data

    International Nuclear Information System (INIS)

    Chagas Moura, Marcio das; Zio, Enrico; Lins, Isis Didier; Droguett, Enrique

    2011-01-01

    Support Vector Machines (SVMs) are kernel-based learning methods, which have been successfully adopted for regression problems. However, their use in reliability applications has not been widely explored. In this paper, a comparative analysis is presented in order to evaluate the SVM effectiveness in forecasting time-to-failure and reliability of engineered components based on time series data. The performance on literature case studies of SVM regression is measured against other advanced learning methods such as the Radial Basis Function, the traditional MultiLayer Perceptron model, Box-Jenkins autoregressive-integrated-moving average and the Infinite Impulse Response Locally Recurrent Neural Networks. The comparison shows that in the analyzed cases, SVM outperforms or is comparable to other techniques. - Highlights: → Realistic modeling of reliability demands complex mathematical formulations. → SVM is proper when the relation input/output is unknown or very costly to be obtained. → Results indicate the potential of SVM for reliability time series prediction. → Reliability estimates support the establishment of adequate maintenance strategies.

  15. A Reliability Assessment Method for the VHTR Safety Systems

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  16. Assessing communication skills in dietetic consultations: the development of the reliable and valid DIET-COMMS tool.

    Science.gov (United States)

    Whitehead, K A; Langley-Evans, S C; Tischler, V A; Swift, J A

    2014-04-01

    There is an increasing emphasis on the development of communication skills for dietitians but few evidence-based assessment tools available. The present study aimed to develop a dietetic-specific, short, reliable and valid assessment tool for measuring communication skills in patient consultations: DIET-COMMS. A literature review and feedback from 15 qualified dietitians were used to establish face and content validity during the development of DIET-COMMS. In total, 113 dietetic students and qualified dietitians were video-recorded undertaking mock consultations, assessed using DIET-COMMS by the lead author, and used to establish intra-rater reliability, as well as construct and predictive validity. Twenty recorded consultations were reassessed by nine qualified dietitians to assess inter-rater reliability: eight of these assessors were interviewed to determine user evaluation. Significant improvements in DIET-COMMS scores were achieved as students and qualified staff progressed through their training and gained experience, demonstrating construct validity, and also by qualified staff attending a training course, indicating predictive validity (P skills in practice was questioned. DIET-COMMS is a short, user-friendly, reliable and valid tool for measuring communication skills in patient consultations with both pre- and post-registration dietitians. Additional work is required to develop a training package for assessors and to identify how DIET-COMMS assessment can acceptably be incorporated into practice. © 2013 The British Dietetic Association Ltd.

  17. A clinical assessment tool used for physiotherapy students--is it reliable?

    Science.gov (United States)

    Lewis, Lucy K; Stiller, Kathy; Hardy, Frances

    2008-01-01

    Educational institutions providing professional programs such as physiotherapy must provide high-quality student assessment procedures. To ensure that assessment is consistent, assessment tools should have an acceptable level of reliability. There is a paucity of research evaluating the reliability of clinical assessment tools used for physiotherapy students. This study evaluated the inter- and intrarater reliability of an assessment tool used for physiotherapy students during a clinical placement. Five clinical educators and one academic participated in the study. Each rater independently marked 22 student written assessments that had been completed by students after viewing a videotaped patient physiotherapy assessment. The raters repeated the marking process 7 weeks later, with the assessments provided in a randomised order. The interrater reliability (Intraclass Correlation Coefficient) for the total scores was 0.32, representing a poor level of reliability. A high level of intrarater reliability (percentage agreement) was found for the clinical educators, with a difference in section scores of one mark or less on 93.4% of occasions. Further research should be undertaken to reevaluate the reliability of this clinical assessment tool following training. The reliability of clinical assessment tools used in other areas of physiotherapy education should be formally measured rather than assumed.

  18. Do in-training evaluation reports deserve their bad reputations? A study of the reliability and predictive ability of ITER scores and narrative comments.

    Science.gov (United States)

    Ginsburg, Shiphra; Eva, Kevin; Regehr, Glenn

    2013-10-01

    Although scores on in-training evaluation reports (ITERs) are often criticized for poor reliability and validity, ITER comments may yield valuable information. The authors assessed across-rotation reliability of ITER scores in one internal medicine program, ability of ITER scores and comments to predict postgraduate year three (PGY3) performance, and reliability and incremental predictive validity of attendings' analysis of written comments. Numeric and narrative data from the first two years of ITERs for one cohort of residents at the University of Toronto Faculty of Medicine (2009-2011) were assessed for reliability and predictive validity of third-year performance. Twenty-four faculty attendings rank-ordered comments (without scores) such that each resident was ranked by three faculty. Mean ITER scores and comment rankings were submitted to regression analyses; dependent variables were PGY3 ITER scores and program directors' rankings. Reliabilities of ITER scores across nine rotations for 63 residents were 0.53 for both postgraduate year one (PGY1) and postgraduate year two (PGY2). Interrater reliabilities across three attendings' rankings were 0.83 for PGY1 and 0.79 for PGY2. There were strong correlations between ITER scores and comments within each year (0.72 and 0.70). Regressions revealed that PGY1 and PGY2 ITER scores collectively explained 25% of variance in PGY3 scores and 46% of variance in PGY3 rankings. Comment rankings did not improve predictions. ITER scores across multiple rotations showed decent reliability and predictive validity. Comment ranks did not add to the predictive ability, but correlation analyses suggest that trainee performance can be measured through these comments.

  19. A Systematic Review of the Reliability and Validity of Behavioural Tests Used to Assess Behavioural Characteristics Important in Working Dogs.

    Science.gov (United States)

    Brady, Karen; Cracknell, Nina; Zulch, Helen; Mills, Daniel Simon

    2018-01-01

    Working dogs are selected based on predictions from tests that they will be able to perform specific tasks in often challenging environments. However, withdrawal from service in working dogs is still a big problem, bringing into question the reliability of the selection tests used to make these predictions. A systematic review was undertaken aimed at bringing together available information on the reliability and predictive validity of the assessment of behavioural characteristics used with working dogs to establish the quality of selection tests currently available for use to predict success in working dogs. The search procedures resulted in 16 papers meeting the criteria for inclusion. A large range of behaviour tests and parameters were used in the identified papers, and so behaviour tests and their underpinning constructs were grouped on the basis of their relationship with positive core affect (willingness to work, human-directed social behaviour, object-directed play tendencies) and negative core affect (human-directed aggression, approach withdrawal tendencies, sensitivity to aversives). We then examined the papers for reports of inter-rater reliability, within-session intra-rater reliability, test-retest validity and predictive validity. The review revealed a widespread lack of information relating to the reliability and validity of measures to assess behaviour and inconsistencies in terminologies, study parameters and indices of success. There is a need to standardise the reporting of these aspects of behavioural tests in order to improve the knowledge base of what characteristics are predictive of optimal performance in working dog roles, improving selection processes and reducing working dog redundancy. We suggest the use of a framework based on explaining the direct or indirect relationship of the test with core affect.

  20. Component reliability data for use in probabilistic safety assessment

    International Nuclear Information System (INIS)

    1988-10-01

    Generic component reliability data is indispensable in any probabilistic safety analysis. It is not realistic to assume that all possible component failures and failure modes modeled in a PSA would be available from the operating experience of a specific plant in a statistically meaningful way. The degree that generic data is used in PSAs varies from case to case. Some studies are totally based on generic data while others use generic data as prior information to be specialized by plant specific data. Most studies, however, finally use a combination where data for certain components come from generic data sources and others from Bayesian updating. The IAEA effort to compile a generic component reliability data base aimed at facilitating the use of data available in the literature and at highlighting pitfalls which deserve special consideration. It was also intended to complement the fault tree and event tree package (PSAPACK) and to facilitate its use. Moreover, it should be noted, that the IAEA has recently initiated a Coordinated Research Program in Reliability Data Collection, Retrieval and Analysis. In this framework the issues identified as most affecting the quality of existing data bases would be addressed. This report presents the results of a compilation made from the specialized literature and includes reliability data for components usually considered in PSA

  1. Training Raters to Assess Adult ADHD: Reliability of Ratings

    Science.gov (United States)

    Adler, Lenard A.; Spencer, Thomas; Faraone, Stephen V.; Reimherr, Fred W.; Kelsey, Douglas; Michelson, David; Biederman, Joseph

    2005-01-01

    The standardization of ADHD ratings in adults is important given their differing symptom presentation. The authors investigated the agreement and reliability of rater standardization in a large-scale trial of atomoxetine in adults with ADHD. Training of 91 raters for the investigator-administered ADHD Rating Scale (ADHDRS-IV-Inv) occurred prior to…

  2. Re-assessing reliability based on survived loads

    NARCIS (Netherlands)

    Schweckendiek, T.

    2011-01-01

    The reliability of flood defenses is often dictated by large uncertainties in the hydraulic loading and the structural resistance. Additional information decreases uncertainty, however, acquiring it is often costly. One source of information, even though in many cases readily available, is hardly

  3. Assessing Assertion: An Investigation of Construct Validity and Reliability.

    Science.gov (United States)

    Kern, Jeffrey M.; MacDonald, Marian L.

    The reliability and meaning of assertiveness tests were explored using 120 female undergraduates. Several self-report inventories (the College Self-Expression Scale, Conflict Resolution Inventory, and a global rating from one to seven) were administered, as were three anxiety measures (Timed Behavior Checklist, response latency, and response…

  4. Pattern Recognition for Reliability Assessment of Water Distribution Networks

    NARCIS (Netherlands)

    Trifunovi?, N.

    2012-01-01

    The study presented in this manuscript investigates the patterns that describe reliability of water distribution networks focusing to the node connectivity, energy balance, and economics of construction, operation and maintenance. A number of measures to evaluate the network resilience has been

  5. Assessment of the Reliability Profiles for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper calculation of reliability profiles is discussed. ULS as well as SLS limit states are formulated. Corrosion due to chloride penetration is the considered deterioration mechanism. Three models for corrosion are formulated. A definition of service lifetime for concrete bridges...

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

    DEFF Research Database (Denmark)

    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...

  7. Technical report on reliability assessment of the digital I and C equipment using reliability block diagram

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Young; Hwang, In Koo; Cha, Kyung Ho; Park, Joo Hyun; Choi, Jong Gyun; Lee, Ki Young; Park, Jong Kyun [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-03-01

    As the operational life-time of nuclear power plants being currently developed is increasing with technology improvements, the life-time of instrumentation and control systems is also required to be met to this plant operational period. The electronic devices are usually expected to be available less than for 10 years. Therefore, an appropriate S and PM (surveillance and preventive maintenance) strategy should be established to secure the reliability and availability of the plants. EPRI-URD requires that the mean time between failures caused by any I and C system failure shall be more than 50 operating years. The methodology to access of the mean time between failures of I and C system is included in this report. 35 refs., 19 figs., 3 tabs. (Author)

  8. [Reliability of the PROFUND index to predict 4-year mortality in polypathological patients].

    Science.gov (United States)

    Díez-Manglano, Jesús; Del Corral Beamonte, Esther; Ramos Ibáñez, Rosa; Lambán Aranda, María Pilar; Toyas Miazza, Carla; Rodero Roldán, María Del Mar; Ortiz Domingo, Concepción; Munilla López, Eulalia; de Escalante Yangüela, Begoña

    2016-09-16

    To determine the usefullness of the PROFUND index to assess the risk of global death after 4 years in polypathological patients. Multicenter prospective cohort (Internal Medicine and Geriatrics) study. Polypathological patients admitted between March 1st and June 30th 2011 were included. For each patient, data concerning age, sex, living at home or in a nursing residence, polypathology categories, Charlson, Barthel and Lawton-Brody indexes, Pfeiffer questionnaire, socio-familial Gijon scale, delirium, number of drugs, hemoglobin and creatinine values were gathered, and the PROFUND index was calculated. The follow-up lasted 4 years. We included 441 patients, 324 from Internal Medicine and 117 from Geriatrics, with a mean age of 80.9 (8.7) years. Of them, 245 (55.6%) were women. Heart (62.7%), neurological (41.4%) and respiratory (37.3%) diseases were the most frequent. Geriatrics inpatients were older and more dependants and presented greater cognitive deterioration. After 4 years, 335 (76%) patients died. Mortality was associated with age, dyspnoea, Barthel index<60, delirium, advanced neoplasia and≥4 admissions in the last year. The area under the curve of the PROFUND index was 0.748, 95% CI 0.689-0.806, P<.001 in Internal Medicine and 0.517, 95% CI 0.369-0.666, P=.818 in Geriatrics patients, respectively. The PROFUND index is a reliable tool for predicting long-term global mortality in polypathological patients from Internal Medicine but not from Geriatrics departments. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

  9. Using personality item characteristics to predict single-item reliability, retest reliability, and self-other agreement

    NARCIS (Netherlands)

    de Vries, Reinout Everhard; Realo, Anu; Allik, Jüri

    2016-01-01

    The use of reliability estimates is increasingly scrutinized as scholars become more aware that test–retest stability and self–other agreement provide a better approximation of the theoretical and practical usefulness of an instrument than its internal reliability. In this study, we investigate item

  10. Fast Reliability Assessing Method for Distribution Network with Distributed Renewable Energy Generation

    Science.gov (United States)

    Chen, Fan; Huang, Shaoxiong; Ding, Jinjin; Ding, Jinjin; Gao, Bo; Xie, Yuguang; Wang, Xiaoming

    2018-01-01

    This paper proposes a fast reliability assessing method for distribution grid with distributed renewable energy generation. First, the Weibull distribution and the Beta distribution are used to describe the probability distribution characteristics of wind speed and solar irradiance respectively, and the models of wind farm, solar park and local load are built for reliability assessment. Then based on power system production cost simulation probability discretization and linearization power flow, a optimal power flow objected with minimum cost of conventional power generation is to be resolved. Thus a reliability assessment for distribution grid is implemented fast and accurately. The Loss Of Load Probability (LOLP) and Expected Energy Not Supplied (EENS) are selected as the reliability index, a simulation for IEEE RBTS BUS6 system in MATLAB indicates that the fast reliability assessing method calculates the reliability index much faster with the accuracy ensured when compared with Monte Carlo method.

  11. The Reliability and Predictive Ability of a Biomarker of Oxidative DNA Damage on Functional Outcomes after Stroke Rehabilitation

    Science.gov (United States)

    Hsieh, Yu-Wei; Lin, Keh-Chung; Korivi, Mallikarjuna; Lee, Tsong-Hai; Wu, Ching-Yi; Wu, Kuen-Yuh

    2014-01-01

    We evaluated the reliability of 8-hydroxy-2′-deoxyguanosine (8-OHdG), and determined its ability to predict functional outcomes in stroke survivors. The rehabilitation effect on 8-OHdG and functional outcomes were also assessed. Sixty-one stroke patients received a 4-week rehabilitation. Urinary 8-OHdG levels were determined by liquid chromatography–tandem mass spectrometry. The test-retest reliability of 8-OHdG was good (interclass correlation coefficient = 0.76). Upper-limb motor function and muscle power determined by the Fugl-Meyer Assessment (FMA) and Medical Research Council (MRC) scales before rehabilitation showed significant negative correlation with 8-OHdG (r = −0.38, r = −0.30; p rehabilitation, we found a fair and significant correlation between 8-OHdG and FMA (r = −0.34) and 8-OHdG and pain (r = 0.26, p rehabilitation. The exploratory study findings conclude that 8-OHdG is a reliable and promising biomarker of oxidative stress and could be a valid predictor of functional outcomes in patients. Monitoring of behavioral indicators along with biomarkers may have crucial benefits in translational stroke research. PMID:24743892

  12. Generation reliability assessment in oligopoly power market using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Haroonabadi, H.; Haghifam, M.R.

    2007-01-01

    This paper addressed issues regarding power generation reliability assessment (HLI) in deregulated power pool markets. Most HLI reliability evaluation methods are based on the loss of load (LOLE) approach which is among the most suitable indices to describe the level of generation reliability. LOLE refers to the time in which load is greater than the amount of available generation. While most reliability assessments deal only with power system constraints, this study considered HLI reliability assessment in an oligopoly power market using Monte Carlo simulation (MCS). It evaluated the sensitivity of the reliability index to different reserve margins and future margins. The reliability index was determined by intersecting the offer and demand curves of power plants and comparing them to other parameters. The paper described the fundamentals of an oligopoly power pool market and proposed an algorithm for HLI reliability assessment for such a market. The proposed method was assessed on the IEEE-Reliability Test System with satisfactory results. In all cases, generation reliability indices were evaluated with different reserve margins and various load levels. 19 refs., 7 figs., 1 appendix

  13. An overall methodology for reliability prediction of mechatronic systems design with industrial application

    International Nuclear Information System (INIS)

    Habchi, Georges; Barthod, Christine

    2016-01-01

    We propose in this paper an overall ten-step methodology dedicated to the analysis and quantification of reliability during the design phase of a mechatronic system, considered as a complex system. The ten steps of the methodology are detailed according to the downward side of the V-development cycle usually used for the design of complex systems. Two main phases of analysis are complementary and cover the ten steps, qualitative analysis and quantitative analysis. The qualitative phase proposes to analyze the functional and dysfunctional behavior of the system and then determine its different failure modes and degradation states, based on external and internal functional analysis, organic and physical implementation, and dependencies between components, with consideration of customer specifications and mission profile. The quantitative phase is used to calculate the reliability of the system and its components, based on the qualitative behavior patterns, and considering data gathering and processing and reliability targets. Systemic approach is used to calculate the reliability of the system taking into account: the different technologies of a mechatronic system (mechanics, electronics, electrical .), dependencies and interactions between components and external influencing factors. To validate the methodology, the ten steps are applied to an industrial system, the smart actuator of Pack'Aero Company. - Highlights: • A ten-step methodology for reliability prediction of mechatronic systems design. • Qualitative and quantitative analysis for reliability evaluation using PN and RBD. • A dependency matrix proposal, based on the collateral and functional interactions. • Models consider mission profile, deterioration, interactions and influent factors. • Application and validation of the methodology on the “Smart Actuator” of PACK’AERO.

  14. Probabilistic risk assessment for a loss of coolant accident in McMaster Nuclear Reactor and application of reliability physics model for modeling human reliability

    Science.gov (United States)

    Ha, Taesung

    A probabilistic risk assessment (PRA) was conducted for a loss of coolant accident, (LOCA) in the McMaster Nuclear Reactor (MNR). A level 1 PRA was completed including event sequence modeling, system modeling, and quantification. To support the quantification of the accident sequence identified, data analysis using the Bayesian method and human reliability analysis (HRA) using the accident sequence evaluation procedure (ASEP) approach were performed. Since human performance in research reactors is significantly different from that in power reactors, a time-oriented HRA model (reliability physics model) was applied for the human error probability (HEP) estimation of the core relocation. This model is based on two competing random variables: phenomenological time and performance time. The response surface and direct Monte Carlo simulation with Latin Hypercube sampling were applied for estimating the phenomenological time, whereas the performance time was obtained from interviews with operators. An appropriate probability distribution for the phenomenological time was assigned by statistical goodness-of-fit tests. The human error probability (HEP) for the core relocation was estimated from these two competing quantities: phenomenological time and operators' performance time. The sensitivity of each probability distribution in human reliability estimation was investigated. In order to quantify the uncertainty in the predicted HEPs, a Bayesian approach was selected due to its capability of incorporating uncertainties in model itself and the parameters in that model. The HEP from the current time-oriented model was compared with that from the ASEP approach. Both results were used to evaluate the sensitivity of alternative huinan reliability modeling for the manual core relocation in the LOCA risk model. This exercise demonstrated the applicability of a reliability physics model supplemented with a. Bayesian approach for modeling human reliability and its potential

  15. Reliability assessment of the containment of a PWR

    International Nuclear Information System (INIS)

    Schueller, G.I.; Wellein, R.; Wittmann, F.H.; Boulahdour, T.; Mihashi, M.; Zorn, N.F.; Bauer, J.

    1981-09-01

    The aim of this research effort was to contribute to the development of methods to quantify the risk involved with nuclear power plants. Using a large component, i.e. the containment of the reference plant BIBLIS B (PWR) as sample structure a reliability analysis was performed which is based on realistic assumptions of loads and material properties. For this purpose in many fields it was necessary to develop new methods, collect data, and where not available, obtain data in tests. This effort concentrated on partial aspects and on the other hand on the development of a methodology for an overall reliability concept. According to the results of the previous project, the keypoints of this effort are the treatment of loss of coolant accidents (small leak), earthquake loading, the possibly resulting crackpropagation in the steel hull, and the structural mechanics and material strength aspects of the reinforced concrete hull subjected to impact loading (aircraft impact). (orig./HP) [de

  16. Assessment of teacher competence using video portfolios: reliability, construct validity and consequential validity

    NARCIS (Netherlands)

    Admiraal, W.; Hoeksma, M.; van de Kamp, M.-T.; van Duin, G.

    2011-01-01

    The richness and complexity of video portfolios endanger both the reliability and validity of the assessment of teacher competencies. In a post-graduate teacher education program, the assessment of video portfolios was evaluated for its reliability, construct validity, and consequential validity.

  17. Reliability and validity of a tool to assess airway management skills in anesthesia trainees

    Directory of Open Access Journals (Sweden)

    Aliya Ahmed

    2016-01-01

    Conclusion: The tool designed to assess bag-mask ventilation and tracheal intubation skills in anesthesia trainees demonstrated excellent inter-rater reliability, fair test-retest reliability, and good construct validity. The authors recommend its use for formative and summative assessment of junior anesthesia trainees.

  18. The nuclear power plant maintenance personnel reliability prediction (NPP/MPRP) effort at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Knee, H.E.; Haas, P.M.; Siegel, A.I.

    1982-01-01

    Human errors committed during maintenance activities are potentially a major contribution to the overall risk associated with the operation of a nuclear power plant (NPP). An NRC-sponsored program at Oak Ridge National Laboratory is attempting to develop a quantitative predictive technique to evaluate the contribution of maintenance errors to the overall NPP risk. The current work includes a survey of the requirements of potential users to ascertain the need for and content of the proposed quantitative model, plus an initial job/task analysis to determine the scope and applicability of various maintenance tasks. In addition, existing human reliability prediction models are being reviewed and assessed with respect to their applicability to NPP maintenance tasks. This paper discusses the status of the program and summarizes the results to date

  19. Advancing methods for reliably assessing motivational interviewing fidelity using the motivational interviewing skills code.

    Science.gov (United States)

    Lord, Sarah Peregrine; Can, Doğan; Yi, Michael; Marin, Rebeca; Dunn, Christopher W; Imel, Zac E; Georgiou, Panayiotis; Narayanan, Shrikanth; Steyvers, Mark; Atkins, David C

    2015-02-01

    The current paper presents novel methods for collecting MISC data and accurately assessing reliability of behavior codes at the level of the utterance. The MISC 2.1 was used to rate MI interviews from five randomized trials targeting alcohol and drug use. Sessions were coded at the utterance-level. Utterance-based coding reliability was estimated using three methods and compared to traditional reliability estimates of session tallies. Session-level reliability was generally higher compared to reliability using utterance-based codes, suggesting that typical methods for MISC reliability may be biased. These novel methods in MI fidelity data collection and reliability assessment provided rich data for therapist feedback and further analyses. Beyond implications for fidelity coding, utterance-level coding schemes may elucidate important elements in the counselor-client interaction that could inform theories of change and the practice of MI. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. ARA and ARI imperfect repair models: Estimation, goodness-of-fit and reliability prediction

    International Nuclear Information System (INIS)

    Toledo, Maria Luíza Guerra de; Freitas, Marta A.; Colosimo, Enrico A.; Gilardoni, Gustavo L.

    2015-01-01

    An appropriate maintenance policy is essential to reduce expenses and risks related to equipment failures. A fundamental aspect to be considered when specifying such policies is to be able to predict the reliability of the systems under study, based on a well fitted model. In this paper, the classes of models Arithmetic Reduction of Age and Arithmetic Reduction of Intensity are explored. Likelihood functions for such models are derived, and a graphical method is proposed for model selection. A real data set involving failures in trucks used by a Brazilian mining is analyzed considering models with different memories. Parameters, namely, shape and scale for Power Law Process, and the efficiency of repair were estimated for the best fitted model. Estimation of model parameters allowed us to derive reliability estimators to predict the behavior of the failure process. These results are a valuable information for the mining company and can be used to support decision making regarding preventive maintenance policy. - Highlights: • Likelihood functions for imperfect repair models are derived. • A goodness-of-fit technique is proposed as a tool for model selection. • Failures in trucks owned by a Brazilian mining are modeled. • Estimation allowed deriving reliability predictors to forecast the future failure process of the trucks

  1. Genotyping cows for the reference increase reliability of genomic prediction in a small breed

    DEFF Research Database (Denmark)

    Thomasen, Jørn Rind; Sørensen, Anders Christian; Lund, Mogens Sandø

    2013-01-01

    We hypothesized that adding cows to the reference population in a breed with a small number of reference bulls would increase reliabilities of genomic breeding values and genetic gain. We tested this premise by comparing two strategies for maintaining the reference population for genetic gain......, inbreeding and reliabilities of genomic predictions: 1) Adding 60 progeny tested bulls each year (B), and 2) in addition to 60 progeny tested bulls, adding 2,000 genotyped cows per year (C). Two breeding schemes were tested: 1) A turbo scheme (T) with only genotyped young bulls used intensively, and 2...... compared to the H-B, at the same level of ∆F. T-C yielded 15% higher ∆G compared t o T-B. Changing the breeding scheme from H-B to H-C increased ∆G by 5.5%. The lowest ∆F was observed with genotyping of cows. Reliabilities of GEBV in the C schemes showed a steep increase in reliability during the first...

  2. A reliable morphological method to assess the age of male Anopheles gambiae

    Directory of Open Access Journals (Sweden)

    Killeen Gerry F

    2006-07-01

    Full Text Available Abstract Background Release of genetically-modified (GM or sterile male mosquitoes for malaria control is hampered by inability to assess the age and mating history of free-living male Anopheles. Methods Age and mating-related changes in the reproductive system of male Anopheles gambiae were quantified and used to fit predictive statistical models. These models, based on numbers of spermatocysts, relative size of sperm reservoir and presence/absence of a clear area around the accessory gland, were evaluated using an independent sample of mosquitoes whose status was blinded during the experiment. Results The number of spermatocysts in male testes decreased with age, and the relative size of their sperm reservoir increased. The presence of a clear area around accessory glands was also linked to age and mating status. A quantitative model was able to categorize males from the blind trial into age groups of young (≤ 4 days and old (> 4 days with an overall efficiency of 89%. Using the parameters of this model, a simple table was compiled that can be used to predict male age. In contrast, mating history could not be reliably assessed as virgins could not be distinguished from mated males. Conclusion Simple assessment of a few morphological traits which are easily collected in the field allows accurate age-grading of male An. gambiae. This simple, yet robust, model enables evaluation of demographic patterns and mortality in wild and released males in populations targeted by GM or sterile male-based control programmes.

  3. Impact of Relationships between Test and Reference Animals and between Reference Animals on Reliability of Genomic Prediction

    DEFF Research Database (Denmark)

    Wu, Xiaoping; Lund, Mogens Sandø; Sun, Dongxiao

    This study investigated reliability of genomic prediction in various scenarios with regard to relationship between test and reference animals and between animals within the reference population. Different reference populations were generated from EuroGenomics data and 1288 Nordic Holstein bulls...... as a common test population. A GBLUP model and a Bayesian mixture model were applied to predict Genomic breeding values for bulls in the test data. Result showed that a closer relationship between test and reference animals led to a higher reliability, while a closer relationship between reference animal...... resulted in a lower reliability. Therefore, the design of reference population is important for improving the reliability of genomic prediction. With regard to model, the Bayesian mixture model in general led to slightly a higher reliability of genomic prediction than the GBLUP model...

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

    Institute of Scientific and Technical Information of China (English)

    Sun Youchao; Shi Jun

    2004-01-01

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

  5. On the use of NDT Data for Reliability-Based Assessment of Existing Timber Structures

    DEFF Research Database (Denmark)

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

    2013-01-01

    The objective of this paper is to address the possibilities of using non-destructive testing (NDT) data for updating information and obtaining adequate characterization of the reliability level of existing timber structures and, also, for assessing the evolution in time of performance...... of these structures when exposed to deterioration. By improving the knowledge upon the mechanical properties of timber, better and more substantiated decisions after a reliability safety assessment are aimed at. Bayesian methods are used to update the mechanical properties of timber and reliability assessment......, and information of NDT is also used to calibrate these models. The proposed approach is used for reliability assessment of different structural timber systems. Reliability of the structural system is assessed regarding the failure consequences of individual elements defined as key elements which were determined...

  6. "The Reliability, Validity, and Utility of Self-Assessment"

    Directory of Open Access Journals (Sweden)

    John A. Ross

    2006-11-01

    Full Text Available Despite widespread use of self-assessment, teachers have doubts about the value and accuracy of the technique. This article reviews research evidence on student self-assessment, finding that (1 self-assessment produces consistent results across items, tasks, and short time periods; (2 self-assessment provides information about student achievement that corresponds only in part to the information generated by teacher assessments; (3 self-assessment contributes to higher student achievement and improved behavior. The central finding of this review is that (4 the strengths of self-assessment can be enhanced through training students how to assess their work and each of the weaknesses of the approach (including inflation of grades can be reduced through teacher action.

  7. A comparative study of the probabilistic fracture mechanics and the stochastic Markovian process approaches for structural reliability assessment

    Energy Technology Data Exchange (ETDEWEB)

    Stavrakakis, G.; Lucia, A.C.; Solomos, G. (Commission of the European Communities, Ispra (Italy). Joint Research Centre)

    1990-01-01

    The two computer codes COVASTOL and RELIEF, developed for the modeling of cumulative damage processes in the framework of probabilistic structural reliability, are compared. They are based respectively on the randomisation of a differential crack growth law and on the theory of discrete Markov processes. The codes are applied for fatigue crack growth predictions using two sets of data of crack propagation curves from specimens. The results are critically analyzed and an extensive discussion follows on the merits and limitations of each code. Their transferability for the reliability assessment of real structures is investigated. (author).

  8. Using the Hemophilia Joint Health Score for assessment of children: Reliability of the Spanish version.

    Science.gov (United States)

    R, Cuesta-Barriuso; A, Torres-Ortuño; S, Pérez-Alenda; J, Carrasco Juan; F, Querol; J, Nieto-Munuera; Ja, López-Pina

    2018-02-27

    Numerous measuring instruments for the evaluation of hemophilic arthropathy have been developed. One of the most used systems is the Hemophilia Joint Health Score (HJHS) given its sensitivity to clinical changes appearing in the joints because of recurrent hemarthrosis. Assessing the interrater reliability, using the Spanish version of the HJHS (version 2.1) in children with hemophilia. Reliability study to assess the interrater reliability of the Spanish version of HJHS. A sample of 36 children aged 7-13 years diagnosed with hemophilia A or B was used. Two physiotherapists performed physical assessments with the Spanish version of the HJHS. Descriptive statistics (range, mean, standard deviation) and the analysis of interrater reliability were calculated. The interrater reliability was heterogeneous since the Kappa coefficient range (ĸ), although significant (p reliability of the Spanish population version of the HJHS is high. This scale should be used generically in evaluating musculoskeletal pediatric patients with hemophilia.

  9. Impact of relationships between test and training animals and among training animals on reliability of genomic prediction.

    Science.gov (United States)

    Wu, X; Lund, M S; Sun, D; Zhang, Q; Su, G

    2015-10-01

    One of the factors affecting the reliability of genomic prediction is the relationship among the animals of interest. This study investigated the reliability of genomic prediction in various scenarios with regard to the relationship between test and training animals, and among animals within the training data set. Different training data sets were generated from EuroGenomics data and a group of Nordic Holstein bulls (born in 2005 and afterwards) as a common test data set. Genomic breeding values were predicted using a genomic best linear unbiased prediction model and a Bayesian mixture model. The results showed that a closer relationship between test and training animals led to a higher reliability of genomic predictions for the test animals, while a closer relationship among training animals resulted in a lower reliability. In addition, the Bayesian mixture model in general led to a slightly higher reliability of genomic prediction, especially for the scenario of distant relationships between training and test animals. Therefore, to prevent a decrease in reliability, constant updates of the training population with animals from more recent generations are required. Moreover, a training population consisting of less-related animals is favourable for reliability of genomic prediction. © 2015 Blackwell Verlag GmbH.

  10. A new lifetime estimation model for a quicker LED reliability prediction

    Science.gov (United States)

    Hamon, B. H.; Mendizabal, L.; Feuillet, G.; Gasse, A.; Bataillou, B.

    2014-09-01

    LED reliability and lifetime prediction is a key point for Solid State Lighting adoption. For this purpose, one hundred and fifty LEDs have been aged for a reliability analysis. LEDs have been grouped following nine current-temperature stress conditions. Stress driving current was fixed between 350mA and 1A and ambient temperature between 85C and 120°C. Using integrating sphere and I(V) measurements, a cross study of the evolution of electrical and optical characteristics has been done. Results show two main failure mechanisms regarding lumen maintenance. The first one is the typically observed lumen depreciation and the second one is a much more quicker depreciation related to an increase of the leakage and non radiative currents. Models of the typical lumen depreciation and leakage resistance depreciation have been made using electrical and optical measurements during the aging tests. The combination of those models allows a new method toward a quicker LED lifetime prediction. These two models have been used for lifetime predictions for LEDs.

  11. Reliability assessment based on small samples of normal distribution

    International Nuclear Information System (INIS)

    Ma Zhibo; Zhu Jianshi; Xu Naixin

    2003-01-01

    When the pertinent parameter involved in reliability definition complies with normal distribution, the conjugate prior of its distributing parameters (μ, h) is of normal-gamma distribution. With the help of maximum entropy and the moments-equivalence principles, the subjective information of the parameter and the sampling data of its independent variables are transformed to a Bayesian prior of (μ,h). The desired estimates are obtained from either the prior or the posterior which is formed by combining the prior and sampling data. Computing methods are described and examples are presented to give demonstrations

  12. The Reliability and Predictive Ability of a Biomarker of Oxidative DNA Damage on Functional Outcomes after Stroke Rehabilitation

    Directory of Open Access Journals (Sweden)

    Yu-Wei Hsieh

    2014-04-01

    Full Text Available We evaluated the reliability of 8-hydroxy-2'-deoxyguanosine (8-OHdG, and determined its ability to predict functional outcomes in stroke survivors. The rehabilitation effect on 8-OHdG and functional outcomes were also assessed. Sixty-one stroke patients received a 4-week rehabilitation. Urinary 8-OHdG levels were determined by liquid chromatography–tandem mass spectrometry. The test-retest reliability of 8-OHdG was good (interclass correlation coefficient = 0.76. Upper-limb motor function and muscle power determined by the Fugl-Meyer Assessment (FMA and Medical Research Council (MRC scales before rehabilitation showed significant negative correlation with 8-OHdG (r = −0.38, r = −0.30; p < 0.05. After rehabilitation, we found a fair and significant correlation between 8-OHdG and FMA (r = −0.34 and 8-OHdG and pain (r = 0.26, p < 0.05. Baseline 8-OHdG was significantly correlated with post-treatment FMA, MRC, and pain scores (r = −0.34, −0.31, and 0.25; p < 0.05, indicating its ability to predict functional outcomes. 8-OHdG levels were significantly decreased, and functional outcomes were improved after rehabilitation. The exploratory study findings conclude that 8-OHdG is a reliable and promising biomarker of oxidative stress and could be a valid predictor of functional outcomes in patients. Monitoring of behavioral indicators along with biomarkers may have crucial benefits in translational stroke research.

  13. Physics-based process modeling, reliability prediction, and design guidelines for flip-chip devices

    Science.gov (United States)

    Michaelides, Stylianos

    Flip Chip on Board (FCOB) and Chip-Scale Packages (CSPs) are relatively new technologies that are being increasingly used in the electronic packaging industry. Compared to the more widely used face-up wirebonding and TAB technologies, flip-chips and most CSPs provide the shortest possible leads, lower inductance, higher frequency, better noise control, higher density, greater input/output (I/O), smaller device footprint and lower profile. However, due to the short history and due to the introduction of several new electronic materials, designs, and processing conditions, very limited work has been done to understand the role of material, geometry, and processing parameters on the reliability of flip-chip devices. Also, with the ever-increasing complexity of semiconductor packages and with the continued reduction in time to market, it is too costly to wait until the later stages of design and testing to discover that the reliability is not satisfactory. The objective of the research is to develop integrated process-reliability models that will take into consideration the mechanics of assembly processes to be able to determine the reliability of face-down devices under thermal cycling and long-term temperature dwelling. The models incorporate the time and temperature-dependent constitutive behavior of various materials in the assembly to be able to predict failure modes such as die cracking and solder cracking. In addition, the models account for process-induced defects and macro-micro features of the assembly. Creep-fatigue and continuum-damage mechanics models for the solder interconnects and fracture-mechanics models for the die have been used to determine the reliability of the devices. The results predicted by the models have been successfully validated against experimental data. The validated models have been used to develop qualification and test procedures for implantable medical devices. In addition, the research has helped develop innovative face

  14. Physics of Failure as a Basis for Solder Elements Reliability Assessment in Wind Turbines

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2012-01-01

    description of the reliability. A physics of failure approach is applied. A SnAg solder component used in power electronics is used as an example. Crack propagation in the SnAg solder is modeled and a model to assess the accumulated plastic strain is proposed based on a physics of failure approach. Based...... on the proposed model it is described how to find the accumulated linear damage and reliability levels for a given temperature loading profile. Using structural reliability methods the reliability levels of the electrical components are assessed by introducing scale factors for stresses....

  15. Practice of value-based distribution reliability assessment (VBDRA) at Scarborough Public Utilities

    International Nuclear Information System (INIS)

    Chen, R-L.

    1995-01-01

    The development of value-based distribution reliability assessment (VBDRA) at Scarborough Public Utilities was described. Load point reliability indices, customer interruption costs (CIC), continuity and service reliability, accuracy of CIC, and the aspects of application of VBDRA were addressed. The application of VBDRA to a long-term rebuild plan for 4.16 kV distribution system was described. The importance of a cost-benefit analysis for implementation of VBDRA was emphasized. In the case of the Scarborough Public Utilities Commission the enhanced feeder reliability assessment was found to influence the allocation of funding to where it provided the most value to customers. 14 refs., 3 tabs., 3 figs

  16. How reliably can climate change and mitigation policy impacts on electric utilities be assessed?

    International Nuclear Information System (INIS)

    Dowlatabadi, H.; Kopp, R.J.; Palmer, K.; De Witt, D.

    1993-01-01

    Numerous mechanisms link climate change and electric utilities. Electricity generation releases radiatively active trace substances (RATS). Significant changes in atmospheric concentration of RATS can lead to a change in regional and global climate regimes. Mitigation action designed to prevent or limit climate change is possible through curbing emissions. Climate change and related mitigation actions impact on electric utilities. Foresight in electric utility planning requires reliable predictions of how the utilities may be affected in the decades ahead. In this paper the impacts of climate change and mitigation policies are noted, and our ability to assess these is reviewed. To this end a suite of models exploring supply and demand questions have been developed. The overall conclusion of the study is that the demand-side uncertainties dominate other unknowns and need to be better characterized and understood. (author)

  17. Reliability assessment of slender concrete columns at the stability failure

    Science.gov (United States)

    Valašík, Adrián; Benko, Vladimír; Strauss, Alfred; Täubling, Benjamin

    2018-01-01

    The European Standard for designing concrete columns within the use of non-linear methods shows deficiencies in terms of global reliability, in case that the concrete columns fail by the loss of stability. The buckling failure is a brittle failure which occurs without warning and the probability of its formation depends on the columns slenderness. Experiments with slender concrete columns were carried out in cooperation with STRABAG Bratislava LTD in Central Laboratory of Faculty of Civil Engineering SUT in Bratislava. The following article aims to compare the global reliability of slender concrete columns with slenderness of 90 and higher. The columns were designed according to methods offered by EN 1992-1-1 [1]. The mentioned experiments were used as basis for deterministic nonlinear modelling of the columns and subsequent the probabilistic evaluation of structural response variability. Final results may be utilized as thresholds for loading of produced structural elements and they aim to present probabilistic design as less conservative compared to classic partial safety factor based design and alternative ECOV method.

  18. Reliability assessment of competing risks with generalized mixed shock models

    International Nuclear Information System (INIS)

    Rafiee, Koosha; Feng, Qianmei; Coit, David W.

    2017-01-01

    This paper investigates reliability modeling for systems subject to dependent competing risks considering the impact from a new generalized mixed shock model. Two dependent competing risks are soft failure due to a degradation process, and hard failure due to random shocks. The shock process contains fatal shocks that can cause hard failure instantaneously, and nonfatal shocks that impact the system in three different ways: 1) damaging the unit by immediately increasing the degradation level, 2) speeding up the deterioration by accelerating the degradation rate, and 3) weakening the unit strength by reducing the hard failure threshold. While the first impact from nonfatal shocks comes from each individual shock, the other two impacts are realized when the condition for a new generalized mixed shock model is satisfied. Unlike most existing mixed shock models that consider a combination of two shock patterns, our new generalized mixed shock model includes three classic shock patterns. According to the proposed generalized mixed shock model, the degradation rate and the hard failure threshold can simultaneously shift multiple times, whenever the condition for one of these three shock patterns is satisfied. An example using micro-electro-mechanical systems devices illustrates the effectiveness of the proposed approach with sensitivity analysis. - Highlights: • A rich reliability model for systems subject to dependent failures is proposed. • The degradation rate and the hard failure threshold can shift simultaneously. • The shift is triggered by a new generalized mixed shock model. • The shift can occur multiple times under the generalized mixed shock model.

  19. Notes on human factors problems in process plant reliability and safety prediction

    International Nuclear Information System (INIS)

    Rasmussen, J.; Taylor, J.R.

    1976-09-01

    The basis for plant operator reliability evaluation is described. Principles for plant design, necessary to permit reliability evaluation, are outlined. Five approaches to the plant operator reliability problem are described. Case stories, illustrating operator reliability problems, are given. (author)

  20. Validated Loads Prediction Models for Offshore Wind Turbines for Enhanced Component Reliability

    DEFF Research Database (Denmark)

    Koukoura, Christina

    To improve the reliability of offshore wind turbines, accurate prediction of their response is required. Therefore, validation of models with site measurements is imperative. In the present thesis a 3.6MW pitch regulated-variable speed offshore wind turbine on a monopole foundation is built...... are used for the modification of the sub-structure/foundation design for possible material savings. First, the background of offshore wind engineering, including wind-wave conditions, support structure, blade loading and wind turbine dynamics are presented. Second, a detailed description of the site...

  1. Uncertainty propagation and sensitivity analysis in system reliability assessment via unscented transformation

    International Nuclear Information System (INIS)

    Rocco Sanseverino, Claudio M.; Ramirez-Marquez, José Emmanuel

    2014-01-01

    The reliability of a system, notwithstanding it intended function, can be significantly affected by the uncertainty in the reliability estimate of the components that define the system. This paper implements the Unscented Transformation to quantify the effects of the uncertainty of component reliability through two approaches. The first approach is based on the concept of uncertainty propagation, which is the assessment of the effect that the variability of the component reliabilities produces on the variance of the system reliability. This assessment based on UT has been previously considered in the literature but only for system represented through series/parallel configuration. In this paper the assessment is extended to systems whose reliability cannot be represented through analytical expressions and require, for example, Monte Carlo Simulation. The second approach consists on the evaluation of the importance of components, i.e., the evaluation of the components that most contribute to the variance of the system reliability. An extension of the UT is proposed to evaluate the so called “main effects” of each component, as well to assess high order component interaction. Several examples with excellent results illustrate the proposed approach. - Highlights: • Simulation based approach for computing reliability estimates. • Computation of reliability variance via 2n+1 points. • Immediate computation of component importance. • Application to network systems

  2. The psychophysiological assessment method for pilot's professional reliability.

    Science.gov (United States)

    Zhang, L M; Yu, L S; Wang, K N; Jing, B S; Fang, C

    1997-05-01

    Previous research has shown that a pilot's professional reliability depends on two relative factors: the pilot's functional state and the demands of task workload. The Psychophysiological Reserve Capacity (PRC) is defined as a pilot's ability to accomplish additive tasks without reducing the performance of the primary task (flight task). We hypothesized that the PRC was a mirror of the pilot's functional state. The purpose of this study was to probe the psychophysiological method for evaluating a pilot's professional reliability on a simulator. The PRC Comprehensive Evaluating System (PRCCES) which was used in the experiment included four subsystems: a) quantitative evaluation system for pilot's performance on simulator; b) secondary task display and quantitative estimating system; c) multiphysiological data monitoring and statistical system; and d) comprehensive evaluation system for pilot PRC. Two studies were performed. In study one, 63 healthy and 13 hospitalized pilots participated. Each pilot performed a double 180 degrees circuit flight program with and without secondary task (three digit operation). The operator performance, score of secondary task and cost of physiological effort were measured and compared by PRCCES in the two conditions. Then, each pilot's flight skill in training was subjectively scored by instructor pilot ratings. In study two, 7 healthy pilots volunteered to take part in the experiment on the effects of sleep deprivation on pilot's PRC. Each participant had PRC tested pre- and post-8 h sleep deprivation. The results show that the PRC values of a healthy pilot was positively correlated with abilities of flexibility, operating and correcting deviation, attention distribution, and accuracy of instrument flight in the air (r = 0.27-0.40, p < 0.05), and negatively correlated with emotional anxiety in flight (r = -0.40, p < 0.05). The values of PRC in healthy pilots (0.61 +/- 0.17) were significantly higher than that of hospitalized pilots

  3. Reliability and availability assessments for the next European Torus

    International Nuclear Information System (INIS)

    Bunde, R.

    1988-01-01

    To achieve its targets in reasonable time, the Next European Torus (NET) must be operated with considerable reliability and availability (R and A). Therefore, failure modes, effects, and criticality analysis (FMECA) of the overall plant and of its major components is already being performed as the design evolves. The present status of the R and A work is described in four steps: First, the R and A targets envisaged for the NET operation are discussed. Then an FMECA covering the overall plant is described, and a more detailed FMECA of major components is presented concerning the toroidal field coil systeml plasma heating systems; protection, instrumentation, and control systems; first wall and blanket, as well as the cooling system. Finally, the R and A results are compared with the targets, and measures for improvements are given

  4. A Valid and Reliable Tool to Assess Nursing Students` Clinical Performance

    OpenAIRE

    Mehrnoosh Pazargadi; Tahereh Ashktorab; Sharareh Khosravi; Hamid Alavi majd

    2013-01-01

    Background: The necessity of a valid and reliable assessment tool is one of the most repeated issues in nursing students` clinical evaluation. But it is believed that present tools are not mostly valid and can not assess students` performance properly.Objectives: This study was conducted to design a valid and reliable assessment tool for evaluating nursing students` performance in clinical education.Methods: In this methodological study considering nursing students` performance definition; th...

  5. Reliability, Validity, and Predictive Utility of the 25-Item Criminogenic Cognitions Scale (CCS).

    Science.gov (United States)

    Tangney, June Price; Stuewig, Jeffrey; Furukawa, Emi; Kopelovich, Sarah; Meyer, Patrick; Cosby, Brandon

    2012-10-01

    Theory, research, and clinical reports suggest that moral cognitions play a role in initiating and sustaining criminal behavior. The 25 item Criminogenic Cognitions Scale (CCS) was designed to tap 5 dimensions: Notions of entitlement; Failure to Accept Responsibility; Short-Term Orientation; Insensitivity to Impact of Crime; and Negative Attitudes Toward Authority. Results from 552 jail inmates support the reliability, validity, and predictive utility of the measure. The CCS was linked to criminal justice system involvement, self-report measures of aggression, impulsivity, and lack of empathy. Additionally, the CCS was associated with violent criminal history, antisocial personality, and clinicians' ratings of risk for future violence and psychopathy (PCL:SV). Furthermore, criminogenic thinking upon incarceration predicted subsequent official reports of inmate misconduct during incarceration. CCS scores varied somewhat by gender and race. Research and applied uses of CCS are discussed.

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

    International Nuclear Information System (INIS)

    Akhavein, A.; Fotuhi Firuzabad, M.

    2011-01-01

    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: → Required reliability level at load points is a concern in modern power systems. → It is important to assess reliability importance of energy producers or generators. → Generators can be ranked based on their impacts on power flow to a selected area. → Ranking of generators is an efficient tool to assess their reliability importance.

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

    OpenAIRE

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

    2007-01-01

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

  8. Semen molecular and cellular features: these parameters can reliably predict subsequent ART outcome in a goat model

    Directory of Open Access Journals (Sweden)

    Mereu Paolo

    2009-11-01

    Full Text Available Abstract Currently, the assessment of sperm function in a raw or processed semen sample is not able to reliably predict sperm ability to withstand freezing and thawing procedures and in vivo fertility and/or assisted reproductive biotechnologies (ART outcome. The aim of the present study was to investigate which parameters among a battery of analyses could predict subsequent spermatozoa in vitro fertilization ability and hence blastocyst output in a goat model. Ejaculates were obtained by artificial vagina from 3 adult goats (Capra hircus aged 2 years (A, B and C. In order to assess the predictive value of viability, computer assisted sperm analyzer (CASA motility parameters and ATP intracellular concentration before and after thawing and of DNA integrity after thawing on subsequent embryo output after an in vitro fertility test, a logistic regression analysis was used. Individual differences in semen parameters were evident for semen viability after thawing and DNA integrity. Results of IVF test showed that spermatozoa collected from A and B lead to higher cleavage rates (0

  9. Reliability Assessment of a Bridge Structure Subjected to Chloride Attack

    DEFF Research Database (Denmark)

    Leira, Bernt J.; Thöns, Sebastian; Nielsen, Michael Havbro Faber

    2018-01-01

    Prediction of the service lifetime of concrete structures with respect to chloride ingress involves a number of parameters that are associated with large uncertainties. Hence, full-scale measurements are strongly in demand. This paper begins by summarizing statistical distributions based on measu......Prediction of the service lifetime of concrete structures with respect to chloride ingress involves a number of parameters that are associated with large uncertainties. Hence, full-scale measurements are strongly in demand. This paper begins by summarizing statistical distributions based...... on measurements taken from the Gimsøystraumen Bridge in Norway. A large number of chloride profiles are available based on concrete coring samples, and for each of these profiles the diffusion coefficient and surface concentration (due to sea spray) are estimated. Extensive measurements of the concrete cover...... depth are also performed. The probability distributions are input into a prediction model for chloride concentration at the steel reinforcement. By also introducing the critical chloride concentration as a random variable, the probability of exceeding the critical threshold is determined as a function...

  10. Developing a novel hierarchical approach for multiscale structural reliability predictions for ultra-high consequence applications

    Energy Technology Data Exchange (ETDEWEB)

    Emery, John M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Coffin, Peter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robbins, Brian A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carroll, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Field, Richard V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jeremy Yoo, Yung Suk [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kacher, Josh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Microstructural variabilities are among the predominant sources of uncertainty in structural performance and reliability. We seek to develop efficient algorithms for multiscale calcu- lations for polycrystalline alloys such as aluminum alloy 6061-T6 in environments where ductile fracture is the dominant failure mode. Our approach employs concurrent multiscale methods, but does not focus on their development. They are a necessary but not sufficient ingredient to multiscale reliability predictions. We have focused on how to efficiently use concurrent models for forward propagation because practical applications cannot include fine-scale details throughout the problem domain due to exorbitant computational demand. Our approach begins with a low-fidelity prediction at the engineering scale that is sub- sequently refined with multiscale simulation. The results presented in this report focus on plasticity and damage at the meso-scale, efforts to expedite Monte Carlo simulation with mi- crostructural considerations, modeling aspects regarding geometric representation of grains and second-phase particles, and contrasting algorithms for scale coupling.

  11. Assessment of modern methods of human factor reliability analysis in PSA studies

    International Nuclear Information System (INIS)

    Holy, J.

    2001-12-01

    The report is structured as follows: Classical terms and objects (Probabilistic safety assessment as a framework for human reliability assessment; Human failure within the PSA model; Basic types of operator failure modelled in a PSA study and analyzed by HRA methods; Qualitative analysis of human reliability; Quantitative analysis of human reliability used; Process of analysis of nuclear reactor operator reliability in a PSA study); New terms and objects (Analysis of dependences; Errors of omission; Errors of commission; Error forcing context); and Overview and brief assessment of human reliability analysis (Basic characteristics of the methods; Assets and drawbacks of the use of each of HRA method; History and prospects of the use of the methods). (P.A.)

  12. Review of Reliability Assessment of Westinghouse SSPS Using SPC by WEC

    International Nuclear Information System (INIS)

    Kang, H. T.; Chung, H. Y.

    2007-01-01

    Westinghouse Electric Company (WEC) has accomplished the reliability assessment of Westinghouse Solid State Protection System (SSPS) in KORI no. 2, 3, 4, and YGN no. 1, 2. In their studies, it is reported that creating a cost-effective plan for improving the reliability of the SSPS and at KORI no. 2, 3 and 4, and YGN no. 1, 2 should be needed while reducing their maintenance cost. In this paper, we reviewed the reliability assessment of Westinghouse SSPS analyzed in two performance standards, availability, and the maintenance expense using Statistic Process Control (SPC). As a result, it is concluded all plants have several failures reported but no effect on the system's availability, and the maintenance expense analysis did not reduce the current maintenance expense by 30%. Therefore, overall review for the reliability assessment is that a new strategy for cost-effective plan and/or upgrade approach for improving the reliability of the aging Westinghouse SSPS should be needed

  13. Advanced Reactor PSA Methodologies for System Reliability Analysis and Source Term Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Grabaskas, D.; Brunett, A.; Passerini, S.; Grelle, A.; Bucknor, M.

    2017-06-26

    Beginning in 2015, a project was initiated to update and modernize the probabilistic safety assessment (PSA) of the GE-Hitachi PRISM sodium fast reactor. This project is a collaboration between GE-Hitachi and Argonne National Laboratory (Argonne), and funded in part by the U.S. Department of Energy. Specifically, the role of Argonne is to assess the reliability of passive safety systems, complete a mechanistic source term calculation, and provide component reliability estimates. The assessment of passive system reliability focused on the performance of the Reactor Vessel Auxiliary Cooling System (RVACS) and the inherent reactivity feedback mechanisms of the metal fuel core. The mechanistic source term assessment attempted to provide a sequence specific source term evaluation to quantify offsite consequences. Lastly, the reliability assessment focused on components specific to the sodium fast reactor, including electromagnetic pumps, intermediate heat exchangers, the steam generator, and sodium valves and piping.

  14. The prediction of reliability and residual life of reactor pressure components

    International Nuclear Information System (INIS)

    Nemec, J.; Antalovsky, S.

    1978-01-01

    The paper deals with the problem of PWR pressure components reliability and residual life evaluation and prediction. A physical model of damage cumulation which serves as a theoretical basis for all considerations presents two major aspects. The first one describes the dependence of the degree of damage in the crack leading-edge in pressure components on the reactor system load-time history, i.e. on the number of transient loads. Both stages, fatigue crack initiation and growth through the wall until the critical length is reached, are investigated. The crack is supposed to initiate at the flaws in a strength weld joint or in the bimetallic weld of the base ferritic steel and the austenitic stainless overlay cladding. The growth rates of developed cracks are analysed in respect to different load-time histories. Important cyclic properties of some steels are derived from the low-cycle fatigue theory. The second aspect is the load-time history-dependent process of precipitation, deformation and radiation aging, characterized entirely by the critical crack-length value mentioned above. The fracture point, defined by the equation ''crack-length=critical value'' and hence the residual life, can be evaluated using this model and verified by in-service inspection. The physical model described is randomized by considering all the parameters of the model as random. Monte Carlo methods are applied and fatigue crack initiation and growth is simulated. This permits evaluation of the reliability and residual life of the component. The distributions of material and load-time history parameters are needed for such simulation. Both the deterministic and computer-simulated probabilistic predictions of reliability and residual life are verified by prior-to-failure sequential testing of data coming from in-service NDT periodical inspections. (author)

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  16. Surgeon Reliability for the Assessment of Lumbar Spinal Stenosis on MRI: The Impact of Surgeon Experience.

    Science.gov (United States)

    Marawar, Satyajit V; Madom, Ian A; Palumbo, Mark; Tallarico, Richard A; Ordway, Nathaniel R; Metkar, Umesh; Wang, Dongliang; Green, Adam; Lavelle, William F

    2017-01-01

    Treating surgeon's visual assessment of axial MRI images to ascertain the degree of stenosis has a critical impact on surgical decision-making. The purpose of this study was to prospectively analyze the impact of surgeon experience on inter-observer and intra-observer reliability of assessing severity of spinal stenosis on MRIs by spine surgeons directly involved in surgical decision-making. Seven fellowship trained spine surgeons reviewed MRI studies of 30 symptomatic patients with lumbar stenosis and graded the stenosis in the central canal, the lateral recess and the foramen at T12-L1 to L5-S1 as none, mild, moderate or severe. No specific instructions were provided to what constituted mild, moderate, or severe stenosis. Two surgeons were "senior" (>fifteen years of practice experience); two were "intermediate" (>four years of practice experience), and three "junior" (< one year of practice experience). The concordance correlation coefficient (CCC) was calculated to assess inter-observer reliability. Seven MRI studies were duplicated and randomly re-read to evaluate inter-observer reliability. Surgeon experience was found to be a strong predictor of inter-observer reliability. Senior inter-observer reliability was significantly higher assessing central(p<0.001), foraminal p=0.005 and lateral p=0.001 than "junior" group.Senior group also showed significantly higher inter-observer reliability that intermediate group assessing foraminal stenosis (p=0.036). In intra-observer reliability the results were contrary to that found in inter-observer reliability. Inter-observer reliability of assessing stenosis on MRIs increases with surgeon experience. Lower intra-observer reliability values among the senior group, although not clearly explained, may be due to the small number of MRIs evaluated and quality of MRI images.Level of evidence: Level 3.

  17. Assessing the reliability of calculated catalytic ammonia synthesis rates

    DEFF Research Database (Denmark)

    Medford, Andrew James; Wellendorff, Jess; Vojvodic, Aleksandra

    2014-01-01

    We introduce a general method for estimating the uncertainty in calculated materials properties based on density functional theory calculations. We illustrate the approach for a calculation of the catalytic rate of ammonia synthesis over a range of transition-metal catalysts. The correlation...... between errors in density functional theory calculations is shown to play an important role in reducing the predicted error on calculated rates. Uncertainties depend strongly on reaction conditions and catalyst material, and the relative rates between different catalysts are considerably better described...

  18. Reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women

    DEFF Research Database (Denmark)

    Clausen, Frederik Banch; Krog, Grethe Risum; Rieneck, Klaus

    2005-01-01

    The objective of this study was to establish a reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women. This test is needed for future prenatal Rh prophylaxis.......The objective of this study was to establish a reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women. This test is needed for future prenatal Rh prophylaxis....

  19. Standardization of domestic human reliability analysis and experience of human reliability analysis in probabilistic safety assessment for NPPs under design

    International Nuclear Information System (INIS)

    Kang, D. I.; Jung, W. D.

    2002-01-01

    This paper introduces the background and development activities of domestic standardization of procedure and method for Human Reliability Analysis (HRA) to avoid the intervention of subjectivity by HRA analyst in Probabilistic Safety Assessment (PSA) as possible, and the review of the HRA results for domestic nuclear power plants under design studied by Korea Atomic Energy Research Institute. We identify the HRA methods used for PSA for domestic NPPs and discuss the subjectivity of HRA analyst shown in performing a HRA. Also, we introduce the PSA guidelines published in USA and review the HRA results based on them. We propose the system of a standard procedure and method for HRA to be developed

  20. Assessment and prediction of wind turbine noise

    International Nuclear Information System (INIS)

    Lowson, M.V.

    1993-01-01

    The significance of basic aerodynamic noise sources for wind turbine noise are assessed, using information on the aero-acoustic mechanisms of other rotors, which have been studied in depth for many years. From the analysis, areas of potential improvement in wind turbine noise prediction are defined. Suggestions are made for approaches to wind turbine noise control which separate the noise problems at cut-in from those at rated power. Some of these offer the possibility of noise reduction without unfavourable effects on performance. Based on this analysis, a new model for prediction of wind turbine noise is presented and comparisons made between prediction and experiment. The model is based on well established aeroacoustic theory and published laboratory data for the two principal sources, inflow turbulence and boundary layer trailing edge interaction. The new method gives good agreement with experiment with the case studied so far. Parametric trends and sensitivities for the model are presented. Comparisons with previous prediction methods are also given. A consequence of the new model is to put more emphasis on boundary layer trailing edge interaction as a noise source. There are prospects for reducing noise from this source detail changes to the wind turbine design. (author)

  1. Reliability and Validity of the Research Methods Skills Assessment

    Science.gov (United States)

    Smith, Tamarah; Smith, Samantha

    2018-01-01

    The Research Methods Skills Assessment (RMSA) was created to measure psychology majors' statistics knowledge and skills. The American Psychological Association's Guidelines for the Undergraduate Major in Psychology (APA, 2007, 2013) served as a framework for development. Results from a Rasch analysis with data from n = 330 undergraduates showed…

  2. Reliability of dune erosion assessment along curved coastlines

    NARCIS (Netherlands)

    Hoonhout, B.M.; Den Heijer, C.

    2010-01-01

    The dune assessment methods used to ensure the safety of the lower areas in The Netherlands are based on simple empirical relations that are, strictly speaking, only valid for infinitely long, uniform and straight coasts. The wide application of these relations is mainly justified due to intentional

  3. reliability reliability

    African Journals Online (AJOL)

    eobe

    Corresponding author, Tel: +234-703. RELIABILITY .... V , , given by the code of practice. However, checks must .... an optimization procedure over the failure domain F corresponding .... of Concrete Members based on Utility Theory,. Technical ...

  4. Assessing predictability of a hydrological stochastic-dynamical system

    Science.gov (United States)

    Gelfan, Alexander

    2014-05-01

    The water cycle includes the processes with different memory that creates potential for predictability of hydrological system based on separating its long and short memory components and conditioning long-term prediction on slower evolving components (similar to approaches in climate prediction). In the face of the Panta Rhei IAHS Decade questions, it is important to find a conceptual approach to classify hydrological system components with respect to their predictability, define predictable/unpredictable patterns, extend lead-time and improve reliability of hydrological predictions based on the predictable patterns. Representation of hydrological systems as the dynamical systems subjected to the effect of noise (stochastic-dynamical systems) provides possible tool for such conceptualization. A method has been proposed for assessing predictability of hydrological system caused by its sensitivity to both initial and boundary conditions. The predictability is defined through a procedure of convergence of pre-assigned probabilistic measure (e.g. variance) of the system state to stable value. The time interval of the convergence, that is the time interval during which the system losses memory about its initial state, defines limit of the system predictability. The proposed method was applied to assess predictability of soil moisture dynamics in the Nizhnedevitskaya experimental station (51.516N; 38.383E) located in the agricultural zone of the central European Russia. A stochastic-dynamical model combining a deterministic one-dimensional model of hydrothermal regime of soil with a stochastic model of meteorological inputs was developed. The deterministic model describes processes of coupled heat and moisture transfer through unfrozen/frozen soil and accounts for the influence of phase changes on water flow. The stochastic model produces time series of daily meteorological variables (precipitation, air temperature and humidity), whose statistical properties are similar

  5. Reliability of the ECHOWS Tool for Assessment of Patient Interviewing Skills.

    Science.gov (United States)

    Boissonnault, Jill S; Evans, Kerrie; Tuttle, Neil; Hetzel, Scott J; Boissonnault, William G

    2016-04-01

    History taking is an important component of patient/client management. Assessment of student history-taking competency can be achieved via a standardized tool. The ECHOWS tool has been shown to be valid with modest intrarater reliability in a previous study but did not demonstrate sufficient power to definitively prove its stability. The purposes of this study were: (1) to assess the reliability of the ECHOWS tool for student assessment of patient interviewing skills and (2) to determine whether the tool discerns between novice and experienced skill levels. A reliability and construct validity assessment was conducted. Three faculty members from the United States and Australia scored videotaped histories from standardized patients taken by students and experienced clinicians from each of these countries. The tapes were scored twice, 3 to 6 weeks apart. Reliability was assessed using interclass correlation coefficients (ICCs) and repeated measures. Analysis of variance models assessed the ability of the tool to discern between novice and experienced skill levels. The ECHOWS tool showed excellent intrarater reliability (ICC [3,1]=.74-.89) and good interrater reliability (ICC [2,1]=.55) as a whole. The summary of performance (S) section showed poor interrater reliability (ICC [2,1]=.27). There was no statistical difference in performance on the tool between novice and experienced clinicians. A possible ceiling effect may occur when standardized patients are not coached to provide complex and obtuse responses to interviewer questions. Variation in familiarity with the ECHOWS tool and in use of the online training may have influenced scoring of the S section. The ECHOWS tool demonstrates excellent intrarater reliability and moderate interrater reliability. Sufficient training with the tool prior to student assessment is recommended. The S section must evolve in order to provide a more discerning measure of interviewing skills. © 2016 American Physical Therapy

  6. Sustainability of transport structures - some aspects of the nonlinear reliability assessment

    Science.gov (United States)

    Pukl, Radomír; Sajdlová, Tereza; Strauss, Alfred; Lehký, David; Novák, Drahomír

    2017-09-01

    Efficient techniques for both nonlinear numerical analysis of concrete structures and advanced stochastic simulation methods have been combined in order to offer an advanced tool for assessment of realistic behaviour, failure and safety assessment of transport structures. The utilized approach is based on randomization of the non-linear finite element analysis of the structural models. Degradation aspects such as carbonation of concrete can be accounted in order predict durability of the investigated structure and its sustainability. Results can serve as a rational basis for the performance and sustainability assessment based on advanced nonlinear computer analysis of the structures of transport infrastructure such as bridges or tunnels. In the stochastic simulation the input material parameters obtained from material tests including their randomness and uncertainty are represented as random variables or fields. Appropriate identification of material parameters is crucial for the virtual failure modelling of structures and structural elements. Inverse analysis using artificial neural networks and virtual stochastic simulations approach is applied to determine the fracture mechanical parameters of the structural material and its numerical model. Structural response, reliability and sustainability have been investigated on different types of transport structures made from various materials using the above mentioned methodology and tools.

  7. Linear Interaction Energy Based Prediction of Cytochrome P450 1A2 Binding Affinities with Reliability Estimation.

    Directory of Open Access Journals (Sweden)

    Luigi Capoferri

    Full Text Available Prediction of human Cytochrome P450 (CYP binding affinities of small ligands, i.e., substrates and inhibitors, represents an important task for predicting drug-drug interactions. A quantitative assessment of the ligand binding affinity towards different CYPs can provide an estimate of inhibitory activity or an indication of isoforms prone to interact with the substrate of inhibitors. However, the accuracy of global quantitative models for CYP substrate binding or inhibition based on traditional molecular descriptors can be limited, because of the lack of information on the structure and flexibility of the catalytic site of CYPs. Here we describe the application of a method that combines protein-ligand docking, Molecular Dynamics (MD simulations and Linear Interaction Energy (LIE theory, to allow for quantitative CYP affinity prediction. Using this combined approach, a LIE model for human CYP 1A2 was developed and evaluated, based on a structurally diverse dataset for which the estimated experimental uncertainty was 3.3 kJ mol-1. For the computed CYP 1A2 binding affinities, the model showed a root mean square error (RMSE of 4.1 kJ mol-1 and a standard error in prediction (SDEP in cross-validation of 4.3 kJ mol-1. A novel approach that includes information on both structural ligand description and protein-ligand interaction was developed for estimating the reliability of predictions, and was able to identify compounds from an external test set with a SDEP for the predicted affinities of 4.6 kJ mol-1 (corresponding to 0.8 pKi units.

  8. Reliability of joint count assessment in rheumatoid arthritis: a systematic literature review.

    Science.gov (United States)

    Cheung, Peter P; Gossec, Laure; Mak, Anselm; March, Lyn

    2014-06-01

    Joint counts are central to the assessment of rheumatoid arthritis (RA) but reliability is an issue. To evaluate the reliability and agreement of joint counts (intra-observer and inter-observer) by health care professionals (physicians, nurses, and metrologists) and patients in RA, and the impact of training and standardization on joint count reliability through a systematic literature review. Articles reporting joint count reliability or agreement in RA in PubMed, EMBase, and the Cochrane library between 1960 and 2012 were selected. Data were extracted regarding tender joint counts (TJCs) and swollen joint counts (SJCs) derived by physicians, metrologists, or patients for intra-observer and inter-observer reliability. In addition, methods and effects of training or standardization were extracted. Statistics expressing reliability such as intraclass correlation coefficients (ICCs) were extracted. Data analysis was primarily descriptive due to high heterogeneity. Twenty-eight studies on health care professionals (HCP) and 20 studies on patients were included. Intra-observer reliability for TJCs and SJCs was good for HCPs and patients (range of ICC: 0.49-0.98). Inter-observer reliability between HCPs for TJCs was higher than for SJCs (range of ICC: 0.64-0.88 vs. 0.29-0.98). Patient inter-observer reliability with HCPs as comparators was better for TJCs (range of ICC: 0.31-0.91) compared to SJCs (0.16-0.64). Nine studies (7 with HCPs and 2 with patients) evaluated consensus or training, with improvement in reliability of TJCs but conflicting evidence for SJCs. Intra- and inter-observer reliability was high for TJCs for HCPs and patients: among all groups, reliability was better for TJCs than SJCs. Inter-observer reliability of SJCs was poorer for patients than HCPs. Data were inconclusive regarding the potential for training to improve SJC reliability. Overall, the results support further evaluation for patient-reported joint counts as an outcome measure. © 2013

  9. Reliability and criterion validity of an observation protocol for working technique assessments in cash register work.

    Science.gov (United States)

    Palm, Peter; Josephson, Malin; Mathiassen, Svend Erik; Kjellberg, Katarina

    2016-06-01

    We evaluated the intra- and inter-observer reliability and criterion validity of an observation protocol, developed in an iterative process involving practicing ergonomists, for assessment of working technique during cash register work for the purpose of preventing upper extremity symptoms. Two ergonomists independently assessed 17 15-min videos of cash register work on two occasions each, as a basis for examining reliability. Criterion validity was assessed by comparing these assessments with meticulous video-based analyses by researchers. Intra-observer reliability was acceptable (i.e. proportional agreement >0.7 and kappa >0.4) for 10/10 questions. Inter-observer reliability was acceptable for only 3/10 questions. An acceptable inter-observer reliability combined with an acceptable criterion validity was obtained only for one working technique aspect, 'Quality of movements'. Thus, major elements of the cashiers' working technique could not be assessed with an acceptable accuracy from short periods of observations by one observer, such as often desired by practitioners. Practitioner Summary: We examined an observation protocol for assessing working technique in cash register work. It was feasible in use, but inter-observer reliability and criterion validity were generally not acceptable when working technique aspects were assessed from short periods of work. We recommend the protocol to be used for educational purposes only.

  10. Reliability and validity of a nutrition and physical activity environmental self-assessment for child care

    Directory of Open Access Journals (Sweden)

    Ammerman Alice S

    2007-07-01

    Full Text Available Abstract Background Few assessment instruments have examined the nutrition and physical activity environments in child care, and none are self-administered. Given the emerging focus on child care settings as a target for intervention, a valid and reliable measure of the nutrition and physical activity environment is needed. Methods To measure inter-rater reliability, 59 child care center directors and 109 staff completed the self-assessment concurrently, but independently. Three weeks later, a repeat self-assessment was completed by a sub-sample of 38 directors to assess test-retest reliability. To assess criterion validity, a researcher-administered environmental assessment was conducted at 69 centers and was compared to a self-assessment completed by the director. A weighted kappa test statistic and percent agreement were calculated to assess agreement for each question on the self-assessment. Results For inter-rater reliability, kappa statistics ranged from 0.20 to 1.00 across all questions. Test-retest reliability of the self-assessment yielded kappa statistics that ranged from 0.07 to 1.00. The inter-quartile kappa statistic ranges for inter-rater and test-retest reliability were 0.45 to 0.63 and 0.27 to 0.45, respectively. When percent agreement was calculated, questions ranged from 52.6% to 100% for inter-rater reliability and 34.3% to 100% for test-retest reliability. Kappa statistics for validity ranged from -0.01 to 0.79, with an inter-quartile range of 0.08 to 0.34. Percent agreement for validity ranged from 12.9% to 93.7%. Conclusion This study provides estimates of criterion validity, inter-rater reliability and test-retest reliability for an environmental nutrition and physical activity self-assessment instrument for child care. Results indicate that the self-assessment is a stable and reasonably accurate instrument for use with child care interventions. We therefore recommend the Nutrition and Physical Activity Self-Assessment for

  11. Modeling human intention formation for human reliability assessment

    International Nuclear Information System (INIS)

    Woods, D.D.; Roth, E.M.; Pople, H. Jr.

    1988-01-01

    This paper describes a dynamic simulation capability for modeling how people form intentions to act in nuclear power plant emergency situations. This modeling tool, Cognitive Environment Simulation or CES, was developed based on techniques from artificial intelligence. It simulates the cognitive processes that determine situation assessment and intention formation. It can be used to investigate analytically what situations and factors lead to intention failures, what actions follow from intention failures (e.g. errors of omission, errors of commission, common mode errors), the ability to recover from errors or additional machine failures, and the effects of changes in the NPP person machine system. One application of the CES modeling environment is to enhance the measurement of the human contribution to risk in probabilistic risk assessment studies. (author)

  12. Can we reliably benchmark health technology assessment organizations?

    Science.gov (United States)

    Drummond, Michael; Neumann, Peter; Jönsson, Bengt; Luce, Bryan; Schwartz, J Sanford; Siebert, Uwe; Sullivan, Sean D

    2012-04-01

    In recent years, there has been growth in the use of health technology assessment (HTA) for making decisions about the reimbursement, coverage, or guidance on the use of health technologies. Given this greater emphasis on the use of HTA, it is important to develop standards of good practice and to benchmark the various HTA organizations against these standards. This study discusses the conceptual and methodological challenges associated with benchmarking HTA organizations and proposes a series of audit questions based on a previously published set of principles of good practice. It is concluded that a benchmarking exercise would be feasible and useful, although the question of who should do the benchmarking requires further discussion. Key issues for further research are the alternative methods for weighting the various principles and for generating an overall score, or summary statement of adherence to the principles. Any weighting system, if developed, would need to be explored in different jurisdictions to assess the extent to which the relative importance of the principles is perceived to vary. Finally, the development and precise wording of the audit questions requires further study, with a view to making the questions as unambiguous as possible, and the reproducibility of the assessments as high as possible.

  13. Reliability of system identification techniques to assess standing balance in healthy elderly

    NARCIS (Netherlands)

    Pasma, Jantsje H.; Engelhart, Denise; Maier, Andrea B.; Aarts, Ronald G.K.M.; Van Gerven, Joop M.A.; Arendzen, J. Hans; Schouten, Alfred C.; Meskers, Carel G.M.; Van Kooij, Herman Der

    2016-01-01

    Objectives System identification techniques have the potential to assess the contribution of the underlying systems involved in standing balance by applying well-known disturbances. We investigated the reliability of standing balance parameters obtained with multivariate closed loop system

  14. Reliability of System Identification Techniques to Assess Standing Balance in Healthy Elderly

    NARCIS (Netherlands)

    Pasma, J.H.; Engelhart, D.; Maier, A.B.; Aarts, R.G.K.M.; Van Gerven, J.M.A.; Arendzen, J.H.; Schouten, A.C.; Meskers, C.G.M.; Van der Kooij, H.

    2016-01-01

    Objectives System identification techniques have the potential to assess the contribution of the underlying systems involved in standing balance by applying well-known disturbances. We investigated the reliability of standing balance parameters obtained with multivariate closed loop system

  15. Extracting information from an ensemble of GCMs to reliably assess future global runoff change

    NARCIS (Netherlands)

    Sperna Weiland, F.C.; Beek, L.P.H. van; Weerts, A.H.; Bierkens, M.F.P.

    2011-01-01

    Future runoff projections derived from different global climate models (GCMs) show large differences. Therefore, within this study the, information from multiple GCMs has been combined to better assess hydrological changes. For projections of precipitation and temperature the Reliability ensemble

  16. Clinical reliability and validity of elbow functional assessment in rheumatoid arthritis.

    NARCIS (Netherlands)

    Boer, Y.A. de; Ende, C.H.M. van den; Eygendaal, D.; Jolie, I.M.M.; Hazes, J.M.W.; Rozing, P.M.

    1999-01-01

    OBJECTIVES: (1) To investigate the measurement characteristics of the Hospital for Special Surgery (HSS) and Mayo Clinic elbow assessment instruments, utilizing methodological criteria including feasibility, reliability, validity, and discriminative ability; and (2) to develop an efficient and

  17. Reliability of voxel gray values in cone beam computed tomography for preoperative implant planning assessment

    NARCIS (Netherlands)

    Parsa, A.; Ibrahim, N.; Hassan, B.; Motroni, A.; van der Stelt, P.; Wismeijer, D.

    2012-01-01

    Purpose: To assess the reliability of cone beam computed tomography (CBCT) voxel gray value measurements using Hounsfield units (HU) derived from multislice computed tomography (MSCT) as a clinical reference (gold standard). Materials and Methods: Ten partially edentulous human mandibular cadavers

  18. Global optimization of maintenance and surveillance testing based on reliability and probabilistic safety assessment. Research project

    International Nuclear Information System (INIS)

    Martorell, S.; Serradell, V.; Munoz, A.; Sanchez, A.

    1997-01-01

    Background, objective, scope, detailed working plan and follow-up and final product of the project ''Global optimization of maintenance and surveillance testing based on reliability and probabilistic safety assessment'' are described

  19. Definition and Reliability Assessment of Elementary Ultrasonographic Findings in Calcium Pyrophosphate Deposition Disease

    DEFF Research Database (Denmark)

    Filippou, Georgios; Scirè, Carlo A; Damjanov, Nemanja

    2017-01-01

    OBJECTIVE: To define the ultrasonographic characteristics of calcium pyrophosphate crystal (CPP) deposits in joints and periarticular tissues and to evaluate the intra- and interobserver reliability of expert ultrasonographers in the assessment of CPP deposition disease (CPPD) according to the ne...

  20. How reliable must advanced nondestructive testing be? A concept for the prediction, validation and raised quality of NDT

    International Nuclear Information System (INIS)

    Nockemann, C.; Tillack, G.R.; Schnitger, D.; Heidt, H.

    1995-01-01

    A concept of the harmonic integration of the following three mainstays of the reliability of ndt is proposed: 1. Theoretical prediction of the reliability as a function of physical parameter by computer modelling of the test problem concerned and the ndt process; maximisation by variation of the parameters. 2. Experimental evaluation of the reliability of ndt processes by the application of statistical methods to test practice. 3. Increasing the reliability by the combination of several ndt methods in a standard DV environment and European interconnection and provision of a distributed databank system. International exchange of experience via telecommunication. (orig.) [de

  1. A Bayesian belief nets based quantitative software reliability assessment for PSA: COTS case study

    International Nuclear Information System (INIS)

    Eom, H. S.; Sung, T. Y.; Jeong, H. S.; Park, J. H.; Kang, H. G.; Lee, K. Y.; Park, J. K

    2002-03-01

    Current reliability assessments of safety critical software embedded in the digital systems in nuclear power plants are based on the rule-based qualitative assessment methods. Then recently practical needs require the quantitative features of software reliability for Probabilistic Safety Assessment (PSA) that is one of important methods being used in assessing the whole safety of nuclear power plant. But conventional quantitative software reliability assessment methods are not enough to get the necessary results in assessing the safety critical software used in nuclear power plants. Thus, current reliability assessment methods for these digital systems exclude the software part or use arbitrary values for the software reliability in the assessment. This reports discusses a Bayesian Belief Nets (BBN) based quantification method that models current qualitative software assessment in formal way and produces quantitative results required for PSA. Commercial Off-The-Shelf (COTS) software dedication process that KAERI developed was applied to the discussed BBN based method for evaluating the plausibility of the proposed method in PSA

  2. Inter- and intra- observer reliability of risk assessment of repetitive work without an explicit method.

    Science.gov (United States)

    Eliasson, Kristina; Palm, Peter; Nyman, Teresia; Forsman, Mikael

    2017-07-01

    A common way to conduct practical risk assessments is to observe a job and report the observed long term risks for musculoskeletal disorders. The aim of this study was to evaluate the inter- and intra-observer reliability of ergonomists' risk assessments without the support of an explicit risk assessment method. Twenty-one experienced ergonomists assessed the risk level (low, moderate, high risk) of eight upper body regions, as well as the global risk of 10 video recorded work tasks. Intra-observer reliability was assessed by having nine of the ergonomists repeat the procedure at least three weeks after the first assessment. The ergonomists made their risk assessment based on his/her experience and knowledge. The statistical parameters of reliability included agreement in %, kappa, linearly weighted kappa, intraclass correlation and Kendall's coefficient of concordance. The average inter-observer agreement of the global risk was 53% and the corresponding weighted kappa (K w ) was 0.32, indicating fair reliability. The intra-observer agreement was 61% and 0.41 (K w ). This study indicates that risk assessments of the upper body, without the use of an explicit observational method, have non-acceptable reliability. It is therefore recommended to use systematic risk assessment methods to a higher degree. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. How to quantify exposure to traumatic stress? Reliability and predictive validity of measures for cumulative trauma exposure in a post-conflict population.

    Science.gov (United States)

    Wilker, Sarah; Pfeiffer, Anett; Kolassa, Stephan; Koslowski, Daniela; Elbert, Thomas; Kolassa, Iris-Tatjana

    2015-01-01

    While studies with survivors of single traumatic experiences highlight individual response variation following trauma, research from conflict regions shows that almost everyone develops posttraumatic stress disorder (PTSD) if trauma exposure reaches extreme levels. Therefore, evaluating the effects of cumulative trauma exposure is of utmost importance in studies investigating risk factors for PTSD. Yet, little research has been devoted to evaluate how this important environmental risk factor can be best quantified. We investigated the retest reliability and predictive validity of different trauma measures in a sample of 227 Ugandan rebel war survivors. Trauma exposure was modeled as the number of traumatic event types experienced or as a score considering traumatic event frequencies. In addition, we investigated whether age at trauma exposure can be reliably measured and improves PTSD risk prediction. All trauma measures showed good reliability. While prediction of lifetime PTSD was most accurate from the number of different traumatic event types experienced, inclusion of event frequencies slightly improved the prediction of current PTSD. As assessing the number of traumatic events experienced is the least stressful and time-consuming assessment and leads to the best prediction of lifetime PTSD, we recommend this measure for research on PTSD etiology.

  4. How to quantify exposure to traumatic stress? Reliability and predictive validity of measures for cumulative trauma exposure in a post-conflict population

    Directory of Open Access Journals (Sweden)

    Sarah Wilker

    2015-11-01

    Full Text Available Background: While studies with survivors of single traumatic experiences highlight individual response variation following trauma, research from conflict regions shows that almost everyone develops posttraumatic stress disorder (PTSD if trauma exposure reaches extreme levels. Therefore, evaluating the effects of cumulative trauma exposure is of utmost importance in studies investigating risk factors for PTSD. Yet, little research has been devoted to evaluate how this important environmental risk factor can be best quantified. Methods: We investigated the retest reliability and predictive validity of different trauma measures in a sample of 227 Ugandan rebel war survivors. Trauma exposure was modeled as the number of traumatic event types experienced or as a score considering traumatic event frequencies. In addition, we investigated whether age at trauma exposure can be reliably measured and improves PTSD risk prediction. Results: All trauma measures showed good reliability. While prediction of lifetime PTSD was most accurate from the number of different traumatic event types experienced, inclusion of event frequencies slightly improved the prediction of current PTSD. Conclusions: As assessing the number of traumatic events experienced is the least stressful and time-consuming assessment and leads to the best prediction of lifetime PTSD, we recommend this measure for research on PTSD etiology.

  5. Reliability-Based Performance Assessment of Damaged Ships

    Science.gov (United States)

    2006-10-01

    37OR.A 2 AceI 2 oce 3 3C7R Main Deck Plan View at 9.906 metre STAA T~SIc ACCa IC 111 tI RO MAO ’ 2 0004 M 3O m 3 STORES) me 3 1 002~s STOR1 PfIS PlnVIS...Vol. 15, pp.7 4 -9 3 . Kaplan , M. Benatar, M., Bentson, J., Achtarides, T.A. (1984). "Analysis and assessment of major uncertainties associated with

  6. The Reliability of In-Training Assessment when Performance Improvement Is Taken into Account

    Science.gov (United States)

    van Lohuizen, Mirjam T.; Kuks, Jan B. M.; van Hell, Elisabeth A.; Raat, A. N.; Stewart, Roy E.; Cohen-Schotanus, Janke

    2010-01-01

    During in-training assessment students are frequently assessed over a longer period of time and therefore it can be expected that their performance will improve. We studied whether there really is a measurable performance improvement when students are assessed over an extended period of time and how this improvement affects the reliability of the…

  7. How will climate novelty influence ecological forecasts? Using the Quaternary to assess future reliability.

    Science.gov (United States)

    Fitzpatrick, Matthew C; Blois, Jessica L; Williams, John W; Nieto-Lugilde, Diego; Maguire, Kaitlin C; Lorenz, David J

    2018-03-23

    Future climates are projected to be highly novel relative to recent climates. Climate novelty challenges models that correlate ecological patterns to climate variables and then use these relationships to forecast ecological responses to future climate change. Here, we quantify the magnitude and ecological significance of future climate novelty by comparing it to novel climates over the past 21,000 years in North America. We then use relationships between model performance and climate novelty derived from the fossil pollen record from eastern North America to estimate the expected decrease in predictive skill of ecological forecasting models as future climate novelty increases. We show that, in the high emissions scenario (RCP 8.5) and by late 21st century, future climate novelty is similar to or higher than peak levels of climate novelty over the last 21,000 years. The accuracy of ecological forecasting models is projected to decline steadily over the coming decades in response to increasing climate novelty, although models that incorporate co-occurrences among species may retain somewhat higher predictive skill. In addition to quantifying future climate novelty in the context of late Quaternary climate change, this work underscores the challenges of making reliable forecasts to an increasingly novel future, while highlighting the need to assess potential avenues for improvement, such as increased reliance on geological analogs for future novel climates and improving existing models by pooling data through time and incorporating assemblage-level information. © 2018 John Wiley & Sons Ltd.

  8. Application of expert elicitation techniques in human reliability, assessment

    International Nuclear Information System (INIS)

    Sanyasi Rao, V.V.S.; Saraf, R.K.; Ghosh, A.K.; Kushwaha, H.S.

    2006-01-01

    Expert elicitation techniques are being used, in the area of technological forecasting, in estimating data needed for analysis when it is either difficult to arrive at the data by experimental means or when it is quite involved to plan and conduct the experiment. In this study, expert elicitation techniques are applied to the evaluation of the frequencies of the various accident sequences that can result from the initiating event (IE) 'High Pressure Process Water (HPPW) system failure' in typical Indian Pressurised Heavy Water Reactor (IPHWR) of the older generation. The Operating Procedure under Emergency Conditions (OPEC) for this IE involves human actions according to a pre-defined procedure. The Human Error Probabilities for all these human actions are obtained using expert elicitation techniques. These techniques aim at eliciting the opinion of the experts in the area of interest with regard to the issue in question. The uncertainty is analysed by employing the measure of dissonance and the most probable range of human error probabilities are arrived at by maximizing this measure. These values are combined using the same procedures mentioned above to yield a distribution representing the uncertainty associated with the predictions. (author)

  9. The reliability and validity of video analysis for the assessment of the clinical signs of concussion in Australian football.

    Science.gov (United States)

    Makdissi, Michael; Davis, Gavin

    2016-10-01

    The objective of this study was to determine the reliability and validity of identifying clinical signs of concussion using video analysis in Australian football. Prospective cohort study. All impacts and collisions potentially resulting in a concussion were identified during 2012 and 2013 Australian Football League seasons. Consensus definitions were developed for clinical signs associated with concussion. For intra- and inter-rater reliability analysis, two experienced clinicians independently assessed 102 randomly selected videos on two occasions. Sensitivity, specificity, positive and negative predictive values were calculated based on the diagnosis provided by team medical staff. 212 incidents resulting in possible concussion were identified in 414 Australian Football League games. The intra-rater reliability of the video-based identification of signs associated with concussion was good to excellent. Inter-rater reliability was good to excellent for impact seizure, slow to get up, motor incoordination, ragdoll appearance (2 of 4 analyses), clutching at head and facial injury. Inter-rater reliability for loss of responsiveness and blank and vacant look was only fair and did not reach statistical significance. The feature with the highest sensitivity was slow to get up (87%), but this sign had a low specificity (19%). Other video signs had a high specificity but low sensitivity. Blank and vacant look (100%) and motor incoordination (81%) had the highest positive predictive value. Video analysis may be a useful adjunct to the side-line assessment of a possible concussion. Video analysis however should not replace the need for a thorough multimodal clinical assessment. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. Construct Validity and Reliability of Structured Assessment of endoVascular Expertise in a Simulated Setting

    DEFF Research Database (Denmark)

    Bech, B; Lönn, L; Falkenberg, M

    2011-01-01

    Objectives To study the construct validity and reliability of a novel endovascular global rating scale, Structured Assessment of endoVascular Expertise (SAVE). Design A Clinical, experimental study. Materials Twenty physicians with endovascular experiences ranging from complete novices to highly....... Validity was analysed by correlating experience with performance results. Reliability was analysed according to generalisability theory. Results The mean score on the 29 items of the SAVE scale correlated well with clinical experience (R = 0.84, P ... with clinical experience (R = -0.53, P validity and reliability of assessment with the SAVE scale was high when applied to performances in a simulation setting with advanced realism. No ceiling effect...

  11. Life cycle reliability assessment of new products—A Bayesian model updating approach

    International Nuclear Information System (INIS)

    Peng, Weiwen; Huang, Hong-Zhong; Li, Yanfeng; Zuo, Ming J.; Xie, Min

    2013-01-01

    The rapidly increasing pace and continuously evolving reliability requirements of new products have made life cycle reliability assessment of new products an imperative yet difficult work. While much work has been done to separately estimate reliability of new products in specific stages, a gap exists in carrying out life cycle reliability assessment throughout all life cycle stages. We present a Bayesian model updating approach (BMUA) for life cycle reliability assessment of new products. Novel features of this approach are the development of Bayesian information toolkits by separately including “reliability improvement factor” and “information fusion factor”, which allow the integration of subjective information in a specific life cycle stage and the transition of integrated information between adjacent life cycle stages. They lead to the unique characteristics of the BMUA in which information generated throughout life cycle stages are integrated coherently. To illustrate the approach, an application to the life cycle reliability assessment of a newly developed Gantry Machining Center is shown

  12. A human hemi-cornea model for eye irritation testing: quality control of production, reliability and predictive capacity.

    Science.gov (United States)

    Engelke, M; Zorn-Kruppa, M; Gabel, D; Reisinger, K; Rusche, B; Mewes, K R

    2013-02-01

    We have developed a 3-dimensional human hemi-cornea which comprises an immortalized epithelial cell line and keratocytes embedded in a collagen stroma. In the present study, we have used MTT reduction of the whole tissue to clarify whether the production of this complex 3-D-model is transferable into other laboratories and whether these tissues can be constructed reproducibly. Our results demonstrate the reproducible production of the hemi-cornea model according to standard operation procedures using 15 independent batches of reconstructed hemi-cornea models in two independent laboratories each. Furthermore, the hemi-cornea tissues have been treated with 20 chemicals of different eye-irritating potential under blind conditions to assess the performance and limitations of our test system comparing three different prediction models. The most suitable prediction model revealed an overall in vitro-in vivo concordance of 80% and 70% in the participating laboratories, respectively, and an inter-laboratory concordance of 80%. Sensitivity of the test was 77% and specificity was between 57% and 86% to discriminate classified from non-classified chemicals. We conclude that additional physiologically relevant endpoints in both epithelium and stroma have to be developed for the reliable prediction of all GHS classes of eye irritation in one stand alone test system. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Reliability of CKD-EPI predictive equation in estimating chronic kidney disease prevalence in the Croatian endemic nephropathy area.

    Science.gov (United States)

    Fuček, Mirjana; Dika, Živka; Karanović, Sandra; Vuković Brinar, Ivana; Premužić, Vedran; Kos, Jelena; Cvitković, Ante; Mišić, Maja; Samardžić, Josip; Rogić, Dunja; Jelaković, Bojan

    2018-02-15

    Chronic kidney disease (CKD) is a significant public health problem and it is not possible to precisely predict its progression to terminal renal failure. According to current guidelines, CKD stages are classified based on the estimated glomerular filtration rate (eGFR) and albuminuria. Aims of this study were to determine the reliability of predictive equation in estimation of CKD prevalence in Croatian areas with endemic nephropathy (EN), compare the results with non-endemic areas, and to determine if the prevalence of CKD stages 3-5 was increased in subjects with EN. A total of 1573 inhabitants of the Croatian Posavina rural area from 6 endemic and 3 non-endemic villages were enrolled. Participants were classified according to the modified criteria of the World Health Organization for EN. Estimated GFR was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI). The results showed a very high CKD prevalence in the Croatian rural area (19%). CKD prevalence was significantly higher in EN then in non EN villages with the lowest eGFR value in diseased subgroup. eGFR correlated significantly with the diagnosis of EN. Kidney function assessment using CKD-EPI predictive equation proved to be a good marker in differentiating the study subgroups, remained as one of the diagnostic criteria for EN.

  14. Reliability assessment and correlation analysis of evaluating orthodontic treatment outcome in Chinese patients.

    Science.gov (United States)

    Song, Guang-Ying; Zhao, Zhi-He; Ding, Yin; Bai, Yu-Xing; Wang, Lin; He, Hong; Shen, Gang; Li, Wei-Ran; Baumrind, Sheldon; Geng, Zhi; Xu, Tian-Min

    2014-03-01

    This study aimed to assess the reliability of experienced Chinese orthodontists in evaluating treatment outcome and to determine the correlations between three diagnostic information sources. Sixty-nine experienced Chinese orthodontic specialists each evaluated the outcome of orthodontic treatment of 108 Chinese patients. Three different information sources: study casts (SC), lateral cephalometric X-ray images (LX) and facial photographs (PH) were generated at the end of treatment for 108 patients selected randomly from six orthodontic treatment centers throughout China. Six different assessments of treatment outcome were made by each orthodontist using data from the three information sources separately and in combination. Each assessment included both ranking and grading for each patient. The rankings of each of the 69 judges for the 108 patients were correlated with the rankings of each of the other judges yielding 13 873 Spearman rs values, ranging from -0.08 to +0.85. Of these, 90% were greater than 0.4, showing moderate-to-high consistency among the 69 orthodontists. In the combined evaluations, study casts were the most significant predictive component (R(2)=0.86, P<0.000 1), while the inclusion of lateral cephalometric films and facial photographs also contributed to a more comprehensive assessment (R(2)=0.96, P<0.000 1). Grading scores for SC+LX and SC+PH were highly significantly correlated with those for SC+LX+PH (r(SC+LX)vs.(SC+LX+PH)=0.96, r(SC+PH)vs.(SC+LX+PH)=0.97), showing that either SC+LX or SC+PH is an excellent substitute for all three combined assessment.

  15. Investigations and technical reviews on the reliability of prediction for migration behavior of radionuclides (H15)

    International Nuclear Information System (INIS)

    Tachikawa, Hirokazu

    2004-02-01

    The research plan of the validation on effects of colloids and organic materials drawn up by the Japan Nuclear Fuel Cycle Development Institute and its' research outcome were reviewed comprehensively by an expert committee established in the Nuclear Safety Research Association. Additionally, experimental investigations for the migration behavior of actinide elements and fission products in engineering barrier and natural barrier medias, and for solution chemistry of them were carried out and discussed by the committee, in order to enhance the reliability of prediction for migration behavior of radionuclides. The subjects investigated by the expert committee are as follows: (1) Research on solubility products of An(III) hydroxide. (2) Diffusion and electromigration behavior of plutonium in buffer material. (3) Analysis of the nuclide solubility in compacted bentonite. (4) Survey of the actual contamination by alpha emitters in steel materials. (author)

  16. Quantitative trait loci markers derived from whole genome sequence data increases the reliability of genomic prediction

    DEFF Research Database (Denmark)

    Brøndum, Rasmus Froberg; Su, Guosheng; Janss, Luc

    2015-01-01

    This study investigated the effect on the reliability of genomic prediction when a small number of significant variants from single marker analysis based on whole genome sequence data were added to the regular 54k single nucleotide polymorphism (SNP) array data. The extra markers were selected...... with the aim of augmenting the custom low-density Illumina BovineLD SNP chip (San Diego, CA) used in the Nordic countries. The single-marker analysis was done breed-wise on all 16 index traits included in the breeding goals for Nordic Holstein, Danish Jersey, and Nordic Red cattle plus the total merit index...... itself. Depending on the trait’s economic weight, 15, 10, or 5 quantitative trait loci (QTL) were selected per trait per breed and 3 to 5 markers were selected to tag each QTL. After removing duplicate markers (same marker selected for more than one trait or breed) and filtering for high pairwise linkage...

  17. Reflow Process Parameters Analysis and Reliability Prediction Considering Multiple Characteristic Values

    Directory of Open Access Journals (Sweden)

    Guo Yu

    2016-01-01

    Full Text Available As a major step surface mount technology, reflow process is the key factor affecting the quality of the final product. The setting parameters and characteristic value of temperature curve shows a nonlinear relationship. So parameter impacts on characteristic values are analyzed and the parameters adjustment process based on orthogonal experiment is proposed in the paper. First, setting parameters are determined and the orthogonal test is designed according to production conditions. Then each characteristic value for temperature profile is calculated. Further, multi-index orthogonal experiment is analyzed for acquiring the setting parameters which impacts the PCBA product quality greater. Finally, reliability prediction is carried out considering the main influencing parameters for providing a theoretical basis of parameters adjustment and product quality evaluation in engineering process.

  18. Prediction method of long-term reliability in improving residual stresses by means of surface finishing

    International Nuclear Information System (INIS)

    Sera, Takehiko; Hirano, Shinro; Chigusa, Naoki; Okano, Shigetaka; Saida, Kazuyoshi; Mochizuki, Masahito; Nishimoto, Kazutoshi

    2012-01-01

    Surface finishing methods, such as Water Jet Peening (WJP), have been applied to welds in some major components of nuclear power plants as a counter measure to Primary Water Stress Corrosion Cracking (PWSCC). In addition, the methods of surface finishing (buffing treatment) is being standardized, and thus the buffing treatment has been also recognized as the well-established method of improving stress. On the other hand, the long-term stability of peening techniques has been confirmed by accelerated test. However, the effectiveness of stress improvement by surface treatment is limited to thin layers and the effect of complicated residual stress distribution in the weld metal beneath the surface is not strictly taken into account for long-term stability. This paper, therefore, describes the accelerated tests, which confirmed that the long-term stability of the layer subjected to buffing treatment was equal to that subjected to WJP. The long-term reliability of very thin stress improved layer was also confirmed through a trial evaluation by thermal elastic-plastic creep analysis, even if the effect of complicated residual stress distribution in the weld metal was excessively taken into account. Considering the above findings, an approach is proposed for constructing the prediction method of the long-term reliability of stress improvement by surface finishing. (author)

  19. Anterior Cruciate Ligament Tear: Reliability of MR Imaging to Predict Stability after Conservative Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hye Won; Ahn, Jin Hwan; Ahn, Joong Mo; Yoon, Young Cheol; Hong, Hyun Pyo; Yoo, So Young; Kim, Seon Woo [Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2007-06-15

    The aim of this study is to evaluate the reliability of MR imaging to predict the stability of the torn anterior cruciate ligament (ACL) after complete recovery of the ligament's continuity. Twenty patients with 20 knee injuries (13 males and 7 females; age range, 20 54) were enrolled in the study. The inclusion criteria were a positive history of acute trauma, diagnosis of the ACL tear by both the physical examination and the MR imaging at the initial presentation, conservative treatment, complete recovery of the continuity of the ligament on the follow up (FU) MR images and availability of the KT-2000 measurements. Two radiologists, who worked in consensus, graded the MR findings with using a 3-point system for the signal intensity, sharpness, straightness and the thickness of the healed ligament. The insufficiency of ACL was categorized into three groups according to the KT-2000 measurements. The statistic correlations between the grades of the MR findings and the degrees of ACL insufficiency were analyzed using the Cochran-Mantel-Haenszel test (p < 0.05). The p-values for each category of the MR findings according to the different groups of the KT-2000 measurements were 0.9180 for the MR signal intensity, 1.0000 for sharpness, 0.5038 for straightness and 0.2950 for thickness of the ACL. The MR findings were not significantly different between the different KT-2000 groups. MR imaging itself is not a reliable examination to predict stability of the ACL rupture outcome, even when the MR images show an intact appearance of the ACL.

  20. The reliability of three psoriasis assessment tools: Psoriasis area and severity index, body surface area and physician global assessment.

    Science.gov (United States)

    Bożek, Agnieszka; Reich, Adam

    2017-08-01

    A wide variety of psoriasis assessment tools have been proposed to evaluate the severity of psoriasis in clinical trials and daily practice. The most frequently used clinical instrument is the psoriasis area and severity index (PASI); however, none of the currently published severity scores used for psoriasis meets all the validation criteria required for an ideal score. The aim of this study was to compare and assess the reliability of 3 commonly used assessment instruments for psoriasis severity: the psoriasis area and severity index (PASI), body surface area (BSA) and physician global assessment (PGA). On the scoring day, 10 trained dermatologists evaluated 9 adult patients with plaque-type psoriasis using the PASI, BSA and PGA. All the subjects were assessed twice by each physician. Correlations between the assessments were analyzed using the Pearson correlation coefficient. Intra-class correlation coefficient (ICC) was calculated to analyze intra-rater reliability, and the coefficient of variation (CV) was used to assess inter-rater variability. Significant correlations were observed among the 3 scales in both assessments. In all 3 scales the ICCs were > 0.75, indicating high intra-rater reliability. The highest ICC was for the BSA (0.96) and the lowest one for the PGA (0.87). The CV for the PGA and PASI were 29.3 and 36.9, respectively, indicating moderate inter-rater variability. The CV for the BSA was 57.1, indicating high inter-rater variability. Comparing the PASI, PGA and BSA, it was shown that the PGA had the highest inter-rater reliability, whereas the BSA had the highest intra-rater reliability. The PASI showed intermediate values in terms of interand intra-rater reliability. None of the 3 assessment instruments showed a significant advantage over the other. A reliable assessment of psoriasis severity requires the use of several independent evaluations simultaneously.

  1. On the applicability of probabilistic analyses to assess the structural reliability of materials and components for solid-oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lara-Curzio, Edgar [ORNL; Radovic, Miladin [Texas A& M University; Luttrell, Claire R [ORNL

    2016-01-01

    The applicability of probabilistic analyses to assess the structural reliability of materials and components for solid-oxide fuel cells (SOFC) is investigated by measuring the failure rate of Ni-YSZ when subjected to a temperature gradient and comparing it with that predicted using the Ceramics Analysis and Reliability Evaluation of Structures (CARES) code. The use of a temperature gradient to induce stresses was chosen because temperature gradients resulting from gas flow patterns generate stresses during SOFC operation that are the likely to control the structural reliability of cell components The magnitude of the predicted failure rate was found to be comparable to that determined experimentally, which suggests that such probabilistic analyses are appropriate for predicting the structural reliability of materials and components for SOFCs. Considerations for performing more comprehensive studies are discussed.

  2. Analysis of complete logical structures in system reliability assessment

    International Nuclear Information System (INIS)

    Amendola, A.; Clarotti, C.A.; Contini, S.; Spizzichino, F.

    1980-01-01

    The application field of the fault-tree techniques has been explored in order to assess whether the AND-OR structures covered all possible actual binary systems. This resulted in the identification of various situations requiring the complete AND-OR-NOT structures for their analysis. We do not use the term non-coherent for such cases, since the monotonicity or not of a structure function is not a characteristic of a system, but of the particular top event being examined. The report presents different examples of complete fault-trees, which can be examined according to different degrees of approximation. In fact, the exact analysis for the determination of the smallest irredundant bases is very time consuming and actually necessary only in some particular cases (multi-state systems, incidental situations). Therefore, together with the exact procedure, the report shows two different methods of logical analysis that permit the reduction of complete fault-trees to AND-OR structures. Moreover, it discusses the problems concerning the evaluation of the probability distribution of the time to first top event occurrence, once the hypothesis of structure function monotonicity is removed

  3. Inter-rater reliability of an observation-based ergonomics assessment checklist for office workers.

    Science.gov (United States)

    Pereira, Michelle Jessica; Straker, Leon Melville; Comans, Tracy Anne; Johnston, Venerina

    2016-12-01

    To establish the inter-rater reliability of an observation-based ergonomics assessment checklist for computer workers. A 37-item (38-item if a laptop was part of the workstation) comprehensive observational ergonomics assessment checklist comparable to government guidelines and up to date with empirical evidence was developed. Two trained practitioners assessed full-time office workers performing their usual computer-based work and evaluated the suitability of workstations used. Practitioners assessed each participant consecutively. The order of assessors was randomised, and the second assessor was blinded to the findings of the first. Unadjusted kappa coefficients between the raters were obtained for the overall checklist and subsections that were formed from question-items relevant to specific workstation equipment. Twenty-seven office workers were recruited. The inter-rater reliability between two trained practitioners achieved moderate to good reliability for all except one checklist component. This checklist has mostly moderate to good reliability between two trained practitioners. Practitioner Summary: This reliable ergonomics assessment checklist for computer workers was designed using accessible government guidelines and supplemented with up-to-date evidence. Employers in Queensland (Australia) can fulfil legislative requirements by using this reliable checklist to identify and subsequently address potential risk factors for work-related injury to provide a safe working environment.

  4. Assessing intraindividual variability in sustained attention: reliability, relation to speed and accuracy, and practice effects

    Directory of Open Access Journals (Sweden)

    HAGEN C. FLEHMIG

    2007-06-01

    Full Text Available We investigated the psychometric properties of competing measures of sustained attention. 179 subjects were assessed twice within seven day's time with a test designed to measure sustained attention, or concentration, respectively. In addition to traditional performance indices [i.e., speed (MRT and accuracy (E%], we evaluated two intraindividual response time (RT variability measures: standard deviation (SDRT and coefficient of variation (CVRT. For the overall test, both indices were reliable. SDRT showed good to acceptable retest reliability for all subtests. For CVRT, retest reliability coefficients ranged from very good to not satisfactory. While the reversed-word recognition test proved highly reliable, the mental calculation test and the arrows test were not sufficiently reliable. CVRT was only slightly correlated but SDRT was highly correlated with MRT. In contrast to substantial practice gains for MRT, SDRT and E%, only CVRT proved to be stable. In conclusion, CVRT appears to be a potential index for assessing performance variability: it is reliable for the overall test, only moderately correlated with speed, and virtually not affected by practice. However, before applying CVRT in practical assessment settings, additional research is required to elucidate the impact of task-specific factors on the reliability of this performance measure.

  5. Reliability Assessment of Wind Farm Electrical System Based on a Probability Transfer Technique

    Directory of Open Access Journals (Sweden)

    Hejun Yang

    2018-03-01

    Full Text Available The electrical system of a wind farm has a significant influence on the wind farm reliability and electrical energy yield. The disconnect switch installed in an electrical system cannot only improve the operating flexibility, but also enhance the reliability for a wind farm. Therefore, this paper develops a probabilistic transfer technique for integrating the electrical topology structure, the isolation operation of disconnect switch, and stochastic failure of electrical equipment into the reliability assessment of wind farm electrical system. Firstly, as the traditional two-state reliability model of electrical equipment cannot consider the isolation operation, so the paper develops a three-state reliability model to replace the two-state model for incorporating the isolation operation. In addition, a proportion apportion technique is presented to evaluate the state probability. Secondly, this paper develops a probabilistic transfer technique based on the thoughts that through transfer the unreliability of electrical system to the energy transmission interruption of wind turbine generators (WTGs. Finally, some novel indices for describing the reliability of wind farm electrical system are designed, and the variance coefficient of the designed indices is used as a convergence criterion to determine the termination of the assessment process. The proposed technique is applied to the reliability assessment of a wind farm with the different topologies. The simulation results show that the proposed techniques are effective in practical applications.

  6. Critical Assessment of the Foundations of Power Transmission and Distribution Reliability Metrics and Standards.

    Science.gov (United States)

    Nateghi, Roshanak; Guikema, Seth D; Wu, Yue Grace; Bruss, C Bayan

    2016-01-01

    The U.S. federal government regulates the reliability of bulk power systems, while the reliability of power distribution systems is regulated at a state level. In this article, we review the history of regulating electric service reliability and study the existing reliability metrics, indices, and standards for power transmission and distribution networks. We assess the foundations of the reliability standards and metrics, discuss how they are applied to outages caused by large exogenous disturbances such as natural disasters, and investigate whether the standards adequately internalize the impacts of these events. Our reflections shed light on how existing standards conceptualize reliability, question the basis for treating large-scale hazard-induced outages differently from normal daily outages, and discuss whether this conceptualization maps well onto customer expectations. We show that the risk indices for transmission systems used in regulating power system reliability do not adequately capture the risks that transmission systems are prone to, particularly when it comes to low-probability high-impact events. We also point out several shortcomings associated with the way in which regulators require utilities to calculate and report distribution system reliability indices. We offer several recommendations for improving the conceptualization of reliability metrics and standards. We conclude that while the approaches taken in reliability standards have made considerable advances in enhancing the reliability of power systems and may be logical from a utility perspective during normal operation, existing standards do not provide a sufficient incentive structure for the utilities to adequately ensure high levels of reliability for end-users, particularly during large-scale events. © 2015 Society for Risk Analysis.

  7. Clinical assessment of scapular positioning in musicians: an intertester reliability study.

    Science.gov (United States)

    Struyf, Filip; Nijs, Jo; De Coninck, Kris; Giunta, Marco; Mottram, Sarah; Meeusen, Romain

    2009-01-01

    The reliability of the measurement of the distance between the posterior border of the acromion and the wall and the reliability of the modified lateral scapular slide test have not been studied. Overall, the reliability of the clinical tools used to assess scapular positioning has not been studied in musicians. To examine the intertester reliability of scapular observation and 2 clinical tests for the assessment of scapular positioning in musicians. Intertester reliability study. University research laboratory. Thirty healthy student musicians at a single university. Two assessors performed a standardized observation protocol, the measurement of the distance between the posterior border of the acromion and the wall, and the modified lateral scapular slide test. Each assessor was blinded to the other's findings. The intertester reliability coefficients (kappa) for the observation in relaxed position, during unloaded movement, and during loaded movement were 0.41, 0.63, and 0.36, respectively. The kappa values for the observation of tilting and winging at rest were 0.48 and 0.42, respectively; during unloaded movement, the kappa values were 0.52 and 0.78, respectively; and with a 1-kg load, the kappa values were 0.24 and 0.50, respectively. The intraclass correlation coefficient (ICC) of the measurement of the acromial distance was 0.72 in relaxed position and 0.75 with the participant actively retracting both shoulders. The ICCs for the modified lateral scapular slide test varied between 0.63 and 0.58. Our results demonstrated that the modified lateral scapular slide test was not a reliable tool to assess scapular positioning in these participants. Our data indicated that scapular observation in the relaxed position and during unloaded abduction in the frontal plane was a reliable assessment tool. The reliability of the measurement of the distance between the posterior border of the acromion and the wall in healthy musicians was moderate.

  8. Assessment of anastomotic reliability with pulse oximetry in graded intestinal ischemia: an experimental study in dogs.

    Science.gov (United States)

    Türkyilmaz, Z; Sönmez, K; Başaklar, A C; Demiroğullari, B; Numanoğlu, V; Ekingen, G; Dursun, A; Altin, M A; Kale, N

    1997-12-01

    Pulse oximetry has been proposed as an appropriate and feasible technique in the assessment of intestinal ischemia in recent years. In this study the authors aimed to assess the reliability of anastomoses in the dog small intestine in which there is graded irreversible ischemia as measured by pulse oxymeter. In a control group of four dogs, without any devascularization, three small bowel anastomoses were formed in each dog. The study group consisted of 12 dogs. In each animal three intestinal segments with different levels of ischemia were created by ligating the marginal vessels proximally and distally in sequence beginning from the midpoint of the segmental vascular arcade. Preanastomotic pulse oximeter readings between 80% and 90% were assigned to mild ischemia, 70% and 80% to moderate, and 60% and 70% to severe ischemia group. Pulse oximetry measurements were obtained from probes applied to the antimesenteric serosal surfaces at the midpoint of small intestinal segments. A total of 48 intestinal segments (12 nonischemic in the control group and 36 with three different levels of ischemia in the study group) were transected in the midpoint and anastomosed in double layers. Postanastomotic SaO2 values were also noted. The anastomoses were evaluated 48 hours later macroscopically if there was any leakage, and biopsy specimens were obtained for histopathologic ischemic gradings. All results were studied statistically. Histopathologic grades between each group were statistically different (P .05), worsening as the level of ischemia increased. Pre- and postanastomotic pulse oximetry measurements correlated very well with the histological gradings (r = -0.90, P anastomoses) in severe ischemia groups. In the moderate ischemia group with an average preanastomotic pulse reading of 76.75%, each of the leaking anastomoses had a postanastomotic pulse measurement of lower than 70%. The finding that the difference between histopathologic grades of control and mild ischemia

  9. The effect of Web-based Braden Scale training on the reliability and precision of Braden Scale pressure ulcer risk assessments.

    Science.gov (United States)

    Magnan, Morris A; Maklebust, Joann

    2008-01-01

    To evaluate the effect of Web-based Braden Scale training on the reliability and precision of pressure ulcer risk assessments made by registered nurses (RN) working in acute care settings. Pretest-posttest, 2-group, quasi-experimental design. Five hundred Braden Scale risk assessments were made on 102 acute care patients deemed to be at various levels of risk for pressure ulceration. Assessments were made by RNs working in acute care hospitals at 3 different medical centers where the Braden Scale was in regular daily use (2 medical centers) or new to the setting (1 medical center). The Braden Scale for Predicting Pressure Sore Risk was used to guide pressure ulcer risk assessments. A Web-based version of the Detroit Medical Center Braden Scale Computerized Training Module was used to teach nurses correct use of the Braden Scale and selection of risk-based pressure ulcer prevention interventions. In the aggregate, RN generated reliable Braden Scale pressure ulcer risk assessments 65% of the time after training. The effect of Web-based Braden Scale training on reliability and precision of assessments varied according to familiarity with the scale. With training, new users of the scale made reliable assessments 84% of the time and significantly improved precision of their assessments. The reliability and precision of Braden Scale risk assessments made by its regular users was unaffected by training. Technology-assisted Braden Scale training improved both reliability and precision of risk assessments made by new users of the scale, but had virtually no effect on the reliability or precision of risk assessments made by regular users of the instrument. Further research is needed to determine best approaches for improving reliability and precision of Braden Scale assessments made by its regular users.

  10. ROBUSTNESS AND PREDICTION ACCURACY OF MACHINE LEARNING FOR OBJECTIVE VISUAL QUALITY ASSESSMENT

    OpenAIRE

    Hines, Andrew; Kendrick, Paul; Barri, Adriaan; Narwaria, Manish; Redi, Judith A.

    2014-01-01

    Machine Learning (ML) is a powerful tool to support the development of objective visual quality assessment metrics, serving as a substitute model for the perceptual mechanisms acting in visual quality appreciation. Nevertheless, the reliability of ML-based techniques within objective quality assessment metrics is often questioned. In this study, the robustness of ML in supporting objective quality assessment is investigated, specifically when the feature set adopted for prediction is suboptim...

  11. Prediction of Global Damage and Reliability Based Upon Sequential Identification and Updating of RC Structures Subject to Earthquakes

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Skjærbæk, P. S.; Köylüoglu, H. U.

    The paper deals with the prediction of global damage and future structural reliability with special emphasis on sensitivity, bias and uncertainty of these predictions dependent on the statistically equivalent realizations of the future earthquake. The predictions are based on a modified Clough......-Johnston single-degree-of-freedom (SDOF) oscillator with three parameters which are calibrated to fit the displacement response and the damage development in the past earthquake....

  12. Advanced error-prediction LDPC with temperature compensation for highly reliable SSDs

    Science.gov (United States)

    Tokutomi, Tsukasa; Tanakamaru, Shuhei; Iwasaki, Tomoko Ogura; Takeuchi, Ken

    2015-09-01

    To improve the reliability of NAND Flash memory based solid-state drives (SSDs), error-prediction LDPC (EP-LDPC) has been proposed for multi-level-cell (MLC) NAND Flash memory (Tanakamaru et al., 2012, 2013), which is effective for long retention times. However, EP-LDPC is not as effective for triple-level cell (TLC) NAND Flash memory, because TLC NAND Flash has higher error rates and is more sensitive to program-disturb error. Therefore, advanced error-prediction LDPC (AEP-LDPC) has been proposed for TLC NAND Flash memory (Tokutomi et al., 2014). AEP-LDPC can correct errors more accurately by precisely describing the error phenomena. In this paper, the effects of AEP-LDPC are investigated in a 2×nm TLC NAND Flash memory with temperature characterization. Compared with LDPC-with-BER-only, the SSD's data-retention time is increased by 3.4× and 9.5× at room-temperature (RT) and 85 °C, respectively. Similarly, the acceptable BER is increased by 1.8× and 2.3×, respectively. Moreover, AEP-LDPC can correct errors with pre-determined tables made at higher temperatures to shorten the measurement time before shipping. Furthermore, it is found that one table can cover behavior over a range of temperatures in AEP-LDPC. As a result, the total table size can be reduced to 777 kBytes, which makes this approach more practical.

  13. On which term is the prediction of the behaviour of glass necessary and reliable?

    International Nuclear Information System (INIS)

    Lefevre, J.

    1997-01-01

    The author questions the ethics of the deep underground storage of high-level radioactive wastes. The time periods that are considered for the confinement are so long that it is completely impossible to predict the way of life of people at that time and the level of knowledge they will have reached. There is a total agreement about the ethics principle of not jeopardizing life and environment of future generations but the difficulty is to draw the limits of this protection. In the regulations of most countries 2 periods of time are defined: the first 500 years and 10.000 years. 500 years is the period of high heat releases due to the decay of most fission products and is also a reasonable time during which the confining site (structures and packages) stays accessible. 10.000 years is considered as the period of time during which predictions are reliable, beyond this time uncertainties become too important and more and more numerous. (A.C.)

  14. Review of Software Reliability Assessment Methodologies for Digital I and C Software of Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jae Hyun; Lee, Seung Jun; Jung, Won Dea [KAERI, Daejeon (Korea, Republic of)

    2014-08-15

    Digital instrumentation and control (I and C) systems are increasingly being applied to current nuclear power plants (NPPs) due to its advantages; zero drift, advanced data calculation capacity, and design flexibility. Accordingly, safety issues of software that is main part of the digital I and C system have been raised. As with hardware components, the software failure in NPPs could lead to a large disaster, therefore failure rate test and reliability assessment of software should be properly performed, and after that adopted in NPPs. However, the reliability assessment of the software is quite different with that of hardware, owing to the nature difference between software and hardware. The one of the most different thing is that the software failures arising from design faults as 'error crystal', whereas the hardware failures are caused by deficiencies in design, production, and maintenance. For this reason, software reliability assessment has been focused on the optimal release time considering the economy. However, the safety goal and public acceptance of the NPPs is so distinctive with other industries that the software in NPPs is dependent on reliability quantitative value rather than economy. The safety goal of NPPs compared to other industries is exceptionally high, so conventional methodologies on software reliability assessment already used in other industries could not adjust to safety goal of NPPs. Thus, the new reliability assessment methodology of the software of digital I and C on NPPs need to be developed. In this paper, existing software reliability assessment methodologies are reviewed to obtain the pros and cons of them, and then to assess the usefulness of each method to software of NPPs.

  15. Review of Software Reliability Assessment Methodologies for Digital I and C Software of Nuclear Power Plants

    International Nuclear Information System (INIS)

    Cho, Jae Hyun; Lee, Seung Jun; Jung, Won Dea

    2014-01-01

    Digital instrumentation and control (I and C) systems are increasingly being applied to current nuclear power plants (NPPs) due to its advantages; zero drift, advanced data calculation capacity, and design flexibility. Accordingly, safety issues of software that is main part of the digital I and C system have been raised. As with hardware components, the software failure in NPPs could lead to a large disaster, therefore failure rate test and reliability assessment of software should be properly performed, and after that adopted in NPPs. However, the reliability assessment of the software is quite different with that of hardware, owing to the nature difference between software and hardware. The one of the most different thing is that the software failures arising from design faults as 'error crystal', whereas the hardware failures are caused by deficiencies in design, production, and maintenance. For this reason, software reliability assessment has been focused on the optimal release time considering the economy. However, the safety goal and public acceptance of the NPPs is so distinctive with other industries that the software in NPPs is dependent on reliability quantitative value rather than economy. The safety goal of NPPs compared to other industries is exceptionally high, so conventional methodologies on software reliability assessment already used in other industries could not adjust to safety goal of NPPs. Thus, the new reliability assessment methodology of the software of digital I and C on NPPs need to be developed. In this paper, existing software reliability assessment methodologies are reviewed to obtain the pros and cons of them, and then to assess the usefulness of each method to software of NPPs

  16. Reliability and Validity of the Greek Migraine Disability Assessment (MIDAS) Questionnaire.

    Science.gov (United States)

    Oikonomidi, Theodora; Vikelis, Michail; Artemiadis, Artemios; Chrousos, George P; Darviri, Christina

    2018-03-01

    The Migraine Disability Assessment (MIDAS) Questionnaire is a reliable and valid instrument for migraine-related disability. Such a tool is needed to quantify migraine-related disability in the Greek population. This validation study aims to assess the test-retest reliability, internal consistency, item discriminant and convergent validity of the Greek translation of the MIDAS. Adults diagnosed with migraine completed the MIDAS Questionnaire on two occasions 3 weeks apart to assess reliability, and completed the RAND-36 to assess validity. Participants (n = 152) had a median MIDAS score of 24 and mostly severe disability (58% were grade IV). The test-retest reliability analysis (N = 59) revealed excellent reliability for the total score. Internal consistency was α = 0.71 for initial and α = 0.82 for retest completion. For item discriminant validity, the correlations between each question and the total score were significant, with high correlations for questions 2-5 (range 0.67 ≤ r ≤ 0.79; p MIDAS score tended to have better wellbeing. Psychometric properties are comparable with those of other published validation studies of the MIDAS and the original. Findings on question 1 show that missing work/school days may be closely related with increased affect issues. The Greek version of the MIDAS Questionnaire has good reliability and validity. This study allowed for cross-cultural comparability of research findings.

  17. Assessment of Advanced Life Support competence when combining different test methods--reliability and validity

    DEFF Research Database (Denmark)

    Ringsted, C; Lippert, F; Hesselfeldt, R

    2007-01-01

    Cardiac Arrest Simulation Test (CASTest) scenarios for the assessments according to guidelines 2005. AIMS: To analyse the reliability and validity of the individual sub-tests provided by ERC and to find a combination of MCQ and CASTest that provides a reliable and valid single effect measure of ALS...... that possessed high reliability, equality of test sets, and ability to discriminate between the two groups of supposedly different ALS competence. CONCLUSIONS: ERC sub-tests of ALS competence possess sufficient reliability and validity. A combined ALS score with equal weighting of one MCQ and one CASTest can...... competence. METHODS: Two groups of participants were included in this randomised, controlled experimental study: a group of newly graduated doctors, who had not taken the ALS course (N=17) and a group of students, who had passed the ALS course 9 months before the study (N=16). Reliability in terms of inter...

  18. Reliability of a Test Battery Designed for Quickly and Safely Assessing Diverse Indices of Neuromuscular Function

    Science.gov (United States)

    Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason, R.; Buxton, Roxanne E.; Lawrence, Emily L.; Sinka, Joseph; Guilliams, Mark E.; Ploutz-Snyder, Lori L.; Bloomberg, Jacob J.

    2010-01-01

    Spaceflight affects nearly every physiological system. Spaceflight-induced alterations in physiological function translate to decrements in functional performance. Purpose: To develop a test battery for quickly and safely assessing diverse indices of neuromuscular performance. I. Quickly: Battery of tests can be completed in approx.30-40 min. II. Safely: a) No eccentric muscle actions or impact forces. b) Tests present little challenge to postural stability. III. Diverse indices: a) Strength: Excellent reliability (ICC = 0.99) b) Central activation: Very good reliability (ICC = 0.87) c) Power: Excellent reliability (ICC = 0.99) d) Endurance: Total work has excellent reliability (ICC = 0.99) e) Force steadiness: Poor reliability (ICC = 0.20 - 0.60) National

  19. Reliability of steam-turbine rotors. Task 1. Lifetime prediction analysis system. Final report

    International Nuclear Information System (INIS)

    Nair, P.K.; Pennick, H.G.; Peters, J.E.; Wells, C.H.

    1982-12-01

    Task 1 of RP 502, Reliability of Steam Turbine Rotors, resulted in the development of a computerized lifetime prediction analysis system (STRAP) for the automatic evaluation of rotor integrity based upon the results of a boresonic examination of near-bore defects. Concurrently an advanced boresonic examination system (TREES), designed to acquire data automatically for lifetime analysis, was developed and delivered to the maintenance shop of a major utility. This system and a semi-automated, state-of-the-art system (BUCS) were evaluated on two retired rotors as part of the Task 2 effort. A modified nonproprietary version of STRAP, called SAFER, is now available for rotor lifetime prediction analysis. STRAP and SAFER share a common fracture analysis postprocessor for rapid evaluation of either conventional boresonic amplitude data or TREES cell data. The final version of this postprocessor contains general stress intensity correlations for elliptical cracks in a radial stress gradient and provision for elastic-plastic instability of the ligament between an imbedded crack and the bore surface. Both linear elastic and ligament rupture models were developed for rapid analysis of linkup within three-dimensional clusters of defects. Bore stress-rupture criteria are included, but a creep-fatigue crack growth data base is not available. Physical and mechanical properties of air-melt 1CrMoV forgings are built into the program; however, only bounding values of fracture toughness versus temperature are available. Owing to the lack of data regarding the probability of flaw detection for the boresonic systems and of quantitative verification of the flaw linkup analysis, automatic evlauation of boresonic results is not recommended, and the lifetime prediction system is currently restricted to conservative, deterministic analysis of specified flaw geometries

  20. Quantification of Wave Model Uncertainties Used for Probabilistic Reliability Assessments of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kofoed, Jens Peter; Sørensen, John Dalsgaard

    2015-01-01

    Wave models used for site assessments are subjected to model uncertainties, which need to be quantified when using wave model results for probabilistic reliability assessments. This paper focuses on determination of wave model uncertainties. Four different wave models are considered, and validation...... data are collected from published scientific research. The bias and the root-mean-square error, as well as the scatter index, are considered for the significant wave height as well as the mean zero-crossing wave period. Based on an illustrative generic example, this paper presents how the quantified...... uncertainties can be implemented in probabilistic reliability assessments....

  1. Determination of Wave Model Uncertainties used for Probabilistic Reliability Assessments of Wave Energy Devices

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kofoed, Jens Peter; Sørensen, John Dalsgaard

    2014-01-01

    Wave models used for site assessments are subject to model uncertainties, which need to be quantified when using wave model results for probabilistic reliability assessments. This paper focuses on determination of wave model uncertainties. Considered are four different wave models and validation...... data is collected from published scientific research. The bias, the root-mean-square error as well as the scatter index are considered for the significant wave height as well as the mean zero-crossing wave period. Based on an illustrative generic example it is shown how the estimated uncertainties can...... be implemented in probabilistic reliability assessments....

  2. Cognitive human reliability analysis for an assessment of the safety significance of complex transients

    International Nuclear Information System (INIS)

    Amico, P.J.; Hsu, C.J.; Youngblood, R.W.; Fitzpatrick, R.G.

    1989-01-01

    This paper reports that as part of a probabilistic assessment of the safety significance of complex transients at certain PWR power plants, it was necessary to perform a cognitive human reliability analysis. To increase the confidence in the results, it was desirable to make use of actual observations of operator response which were available for the assessment. An approach was developed which incorporated these observations into the human cognitive reliability (HCR) modeling approach. The results obtained provided additional insights over what would have been found using other approaches. These insights were supported by the observations, and it is suggested that this approach be considered for use in future probabilistic safety assessments

  3. Orthopaedic nurses' knowledge and interrater reliability of neurovascular assessments with 2-point discrimination test.

    Science.gov (United States)

    Turney, Jennifer; Raley Noble, Deana; Kim, Son Chae

    2013-01-01

    : This study was conducted to evaluate the effects of education on knowledge and interrater reliability of neurovascular assessments with 2-point discrimination (2-PD) test among pediatric orthopaedic nurses. : A pre- and posttest study was done among 60 nurses attending 2-hour educational sessions. Neurovascular assessments with 2-PD test were performed on 64 casted pediatric patients by the nurses and 5 nurse experts before and after the educational sessions. : The mean neurovascular assessment knowledge score was improved at posteducation compared with the preeducation (p < .001). The 2-PD test interrater reliability also improved from Cohen's kappa value of 0.24-0.48 at posteducation. : The 2-hour educational session may be effective in improving nurses' knowledge and the interrater reliability of neurovascular assessment with 2-PD test.

  4. Reliability Assessment Method of Reactor Protection System Software by Using V and Vbased Bayesian Nets

    International Nuclear Information System (INIS)

    Eom, H. S.; Park, G. Y.; Kang, H. G.; Son, H. S.

    2010-07-01

    Developed a methodology which can be practically used in quantitative reliability assessment of a safety c ritical software for a protection system of nuclear power plants. The base of the proposed methodology is V and V being used in the nuclear industry, which means that it is not affected with specific software development environments or parameters that are necessary for the reliability calculation. Modular and formal sub-BNs in the proposed methodology is useful tool to constitute the whole BN model for reliability assessment of a target software. The proposed V and V based BN model estimates the defects in the software according to the performance of V and V results and then calculate reliability of the software. A case study was carried out to validate the proposed methodology. The target software is the RPS SW which was developed by KNICS project

  5. Investigating the Validity and Reliability of the Vanderbilt Assessment of Leadership in Education

    Science.gov (United States)

    Porter, Andrew C.; Polikoff, Morgan S.; Goldring, Ellen B.; Murphy, Joseph; Elliott, Stephen N.; May, Henry

    2010-01-01

    The Vanderbilt Assessment of Leadership in Education (VAL-ED) is a multirater assessment of principals' learning-centered leadership. The instrument was developed based on the Standards for Educational and Psychological Testing. In this article, we report on the validity and reliability evidence for the VAL-ED accumulated in a national field…

  6. Nurses assessing pain with the Nociception Coma Scale: interrater reliability and validity

    NARCIS (Netherlands)

    Vink, Peter; Eskes, Anne Maria; Lindeboom, Robert; van den Munckhof, Pepijn; Vermeulen, Hester

    2014-01-01

    The Nociception Coma Scale (NCS) is a pain observation tool, developed for patients with disorders of consciousness (DOC) due to acquired brain injury (ABI). The aim of this study was to assess the interrater reliability of the NCS and NCS-R among nurses for the assessment of pain in ABI patients

  7. Assessment of disabilities in stroke patients with apraxia : Internal consistency and inter-observer reliability

    NARCIS (Netherlands)

    van Heugten, CM; Dekker, J; Deelman, BG; Stehmann-Saris, JC; Kinebanian, A

    1999-01-01

    In this paper the internal consistency and inter-observer reliability of the assessment of disabilities in stroke patients with apraxia is presented. Disabilities were assessed by means of observation of activities of daily living (ADL). The study was conducted at occupational therapy departments in

  8. Assessment of disabilities in stroke patients with apraxia: internal consistency and inter-observer reliability.

    NARCIS (Netherlands)

    Heugten, C.M. van; Dekker, J.; Deelman, B.G.; Stehmann-Saris, J.C.; Kinebanian, A.

    1999-01-01

    In this paper the internal consistency and inter-observer reliability of the assessment of disabilities in stroke patients with apraxia is presented. Disabilities were assessed by means of observation of activities of daily living (ADL). The study was conducted at occupational therapy departments in

  9. Experiences in Germany with reliability data assessment, results and current problems

    International Nuclear Information System (INIS)

    Homke, P.; Kutsch, W.; Lindauer, E.

    1982-01-01

    This paper gives a survey on reliability data assessment in the FRG. The activities, which were carried out for the German Risk Assessment Study are presented together with selected results. A systematic data collection in a nuclear power plant is described and the experiences are discussed, which were gained in this project

  10. Diagnosing paratonia in the demented elderly : reliability and validity of the Paratonia Assessment Instrument (PAI)

    NARCIS (Netherlands)

    Hobbelen, Hans; Koopmans, Raymond T C M; Verhey, Frans R J; Habraken, Kitty M; de Bie, Rob A.

    BACKGROUND: Paratonia is one of the associated movement disorders characteristic of dementia. The aim of this study was to develop an assessment tool (the Paratonia Assessment Instrument, PAI), based on the new consensus definition of paratonia. An additional aim was to investigate the reliability

  11. Diagnosing paratonia in the demented elderly: reliability and validity of the Paratonia Assessment Instrument (PAI).

    NARCIS (Netherlands)

    Hobbelen, J.S.; Koopmans, R.T.C.M.; Verhey, F.R.J.; Habraken, K.M.; Bie, R.A. de

    2008-01-01

    BACKGROUND: Paratonia is one of the associated movement disorders characteristic of dementia. The aim of this study was to develop an assessment tool (the Paratonia Assessment Instrument, PAI), based on the new consensus definition of paratonia. An additional aim was to investigate the reliability

  12. A reliable method for ageing of whiting (Merlangius merlangus) for use in stock assessment and management

    DEFF Research Database (Denmark)

    Ross, Stine Dalmann; Hüssy, Karin

    2013-01-01

    Accurate age estimation is important for stock assessment and management. The importance of reliable ageing is emphasized by the impending analytical assessment of whiting (Merlangius merlangus) in the Baltic Sea. Whiting is a top predator in the western Baltic Sea, where it is fished commercially...

  13. Reliability and Validity of the PAQ-C Questionnaire to Assess Physical Activity in Children

    Science.gov (United States)

    Benítez-Porres, Javier; López-Fernández, Iván; Raya, Juan Francisco; Álvarez Carnero, Sabrina; Alvero-Cruz, José Ramón; Álvarez Carnero, Elvis

    2016-01-01

    Background: Physical activity (PA) assessment by questionnaire is a cornerstone in the field of sport epidemiology studies. The Physical Activity Questionnaire for Children (PAQ-C) has been used widely to assess PA in healthy school populations. The aim of this study was to evaluate the reliability and validity of the PAQ-C questionnaire in…

  14. Standardized Patients Provide a Reliable Assessment of Athletic Training Students' Clinical Skills

    Science.gov (United States)

    Armstrong, Kirk J.; Jarriel, Amanda J.

    2016-01-01

    Context: Providing students reliable objective feedback regarding their clinical performance is of great value for ongoing clinical skill assessment. Since a standardized patient (SP) is trained to consistently portray the case, students can be assessed and receive immediate feedback within the same clinical encounter; however, no research, to our…

  15. The Reliability and Structure of the Classroom Assessment Scoring System in German Pre-Schools

    Science.gov (United States)

    Stuck, Andrea; Kammermeyer, Gisela; Roux, Susanna

    2016-01-01

    This study examined the reliability and structure of the Classroom Assessment Scoring System (CLASS; Pianta, R. C., K. M. La Paro, and B. K. Hamre. 2008. "Classroom Assessment Scoring System. Manual Pre-K." Baltimore, MD: Brookes) and the quality of interactional processes in a German pre-school setting, drawing on a sample of 390…

  16. A Turkish version of myocardial infarction dimensional assessment scale (TR-MIDAS): reliability-validity assesment.

    Science.gov (United States)

    Uysal, Hilal; Ozcan, Şeyda

    2011-06-01

    Many new measuring devices have been developed so that broader psychometric measurements in the coronary artery disease, disease-specific health status measurements, and identification of the broader quality of life can be performed in the recent years. The study was intended to determine whether, and to what extent, MIDAS is a valid and reliable measurement to the patients suffering from myocardial infarction for the first time in Turkey. The research was conducted with the patients hospitalized and treated with myocardial infarction in the cardiology departments of 2 hospitals in Istanbul, Turkey, between 2007 and 2008. Psychometric evaluations of TR-MIDAS were used for validity studies; language validity, content validity, construct validity were examined. For reliability studies; the tool's internal consistency reliability, Cronbach's alpha reliability coefficient, and test-retest reliability were completed. The instrument's content validity index was determined to be "0.95". Principal component analysis revealed six factors with an eigenvalue >1.5. Cronbach's alpha was found to be 0.89 for total scale which was an acceptable value. The total's test-retest reliability was 0.51 (p<0.01). Data obtained at the end of the study supports that Turkish Myocardial Infarction Dimensional Assessment Scale is a valid and reliable instrument as a disease-specific scale to assess the patients' quality of life suffering from myocardial infarction in Turkey. Copyright © 2010 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.

  17. Damage Model for Reliability Assessment of Solder Joints in Wind Turbines

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2012-01-01

    environmental factors. Reliability assessment for such type of products conventionally is performed by classical reliability techniques based on test data. Usually conventional reliability approaches are time and resource consuming activities. Thus in this paper we choose a physics of failure approach to define...... damage model by Miner’s rule. Our attention is focused on crack propagation in solder joints of electrical components due to the temperature loadings. Based on the proposed method it is described how to find the damage level for a given temperature loading profile. The proposed method is discussed...

  18. An attempt to use FMEA method for an approximate reliability assessment of machinery

    Directory of Open Access Journals (Sweden)

    Przystupa Krzysztof

    2017-01-01

    Full Text Available The paper presents a modified FMEA (Failure Mode and Effect Analysis method to assess reliability of the components that make up a wrench type 2145: MAX Impactol TM Driver Ingersoll Rand Company. This case concerns the analysis of reliability in conditions, when full service data is not known. The aim of the study is to determine the weakest element in the design of the tool.

  19. Seismic reliability assessment methodology for CANDU concrete containment structures-phase 11

    International Nuclear Information System (INIS)

    Hong, H.P.

    1996-07-01

    This study was undertaken to verify a set of load factors for reliability-based seismic evaluation of CANDU containment structures in Eastern Canada. Here, the new, site-specific, results of probabilistic seismic hazard assessment (response spectral velocity) were applied. It was found that the previously recommended load factors are relatively insensitive to the new seismic hazard information, and are adequate for a reliability-based seismic evaluation process. (author). 4 refs., 5 tabs., 9 figs

  20. Feasibility and reliability of frailty assessment in the critically ill: a systematic review.

    Science.gov (United States)

    Pugh, Richard J; Ellison, Amy; Pye, Kate; Subbe, Christian P; Thorpe, Chris M; Lone, Nazir I; Clegg, Andrew

    2018-02-26

    For healthcare systems, an ageing population poses challenges in the delivery of equitable and effective care. Frailty assessment has the potential to improve care in the intensive care setting, but applying assessment tools in critical illness may be problematic. The aim of this systematic review was to evaluate evidence for the feasibility and reliability of frailty assessment in critical care. Our primary search was conducted in Medline, Medline In-process, EMBASE, CINAHL, PsycINFO, AMED, Cochrane Database of Systematic Reviews, and Web of Science (January 2001 to October 2017). We included observational studies reporting data on feasibility and reliability of frailty assessment in the critical care setting in patients 16 years and older. Feasibility was assessed in terms of timing of evaluation, the background, training and expertise required for assessors, and reliance upon proxy input. Reliability was assessed in terms of inter-rater reliability. Data from 11 study publications are included, representing 8 study cohorts and 7761 patients. Proxy involvement in frailty assessment ranged from 58 to 100%. Feasibility data were not well-reported overall, but the exclusion rate due to lack of proxy availability ranged from 0 to 45%, the highest rate observed where family involvement was mandatory and the assessment tool relatively complex (frailty index, FI). Conventional elements of frailty phenotype (FP) assessment required modification prior to use in two studies. Clinical staff tended to use a simple judgement-based tool, the clinical frailty scale (CFS). Inter-rater reliability was reported in one study using the CFS and although a good level of agreement was observed between clinician assessments, this was a small and single-centre study. Though of unproven reliability in the critically ill, CFS was the tool used most widely by critical care clinical staff. Conventional FP assessment required modification for general application in critical care, and an FI

  1. HitPredict version 4: comprehensive reliability scoring of physical protein?protein interactions from more than 100 species

    OpenAIRE

    L?pez, Yosvany; Nakai, Kenta; Patil, Ashwini

    2015-01-01

    HitPredict is a consolidated resource of experimentally identified, physical protein?protein interactions with confidence scores to indicate their reliability. The study of genes and their inter-relationships using methods such as network and pathway analysis requires high quality protein?protein interaction information. Extracting reliable interactions from most of the existing databases is challenging because they either contain only a subset of the available interactions, or a mixture of p...

  2. Relevance and reliability of experimental data in human health risk assessment of pesticides.

    Science.gov (United States)

    Kaltenhäuser, Johanna; Kneuer, Carsten; Marx-Stoelting, Philip; Niemann, Lars; Schubert, Jens; Stein, Bernd; Solecki, Roland

    2017-08-01

    Evaluation of data relevance, reliability and contribution to uncertainty is crucial in regulatory health risk assessment if robust conclusions are to be drawn. Whether a specific study is used as key study, as additional information or not accepted depends in part on the criteria according to which its relevance and reliability are judged. In addition to GLP-compliant regulatory studies following OECD Test Guidelines, data from peer-reviewed scientific literature have to be evaluated in regulatory risk assessment of pesticide active substances. Publications should be taken into account if they are of acceptable relevance and reliability. Their contribution to the overall weight of evidence is influenced by factors including test organism, study design and statistical methods, as well as test item identification, documentation and reporting of results. Various reports make recommendations for improving the quality of risk assessments and different criteria catalogues have been published to support evaluation of data relevance and reliability. Their intention was to guide transparent decision making on the integration of the respective information into the regulatory process. This article describes an approach to assess the relevance and reliability of experimental data from guideline-compliant studies as well as from non-guideline studies published in the scientific literature in the specific context of uncertainty and risk assessment of pesticides. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Validity, reliability and support for implementation of independence-scaled procedural assessment in laparoscopic surgery.

    Science.gov (United States)

    Kramp, Kelvin H; van Det, Marc J; Veeger, Nic J G M; Pierie, Jean-Pierre E N

    2016-06-01

    There is no widely used method to evaluate procedure-specific laparoscopic skills. The first aim of this study was to develop a procedure-based assessment method. The second aim was to compare its validity, reliability and feasibility with currently available global rating scales (GRSs). An independence-scaled procedural assessment was created by linking the procedural key steps of the laparoscopic cholecystectomy to an independence scale. Subtitled and blinded videos of a novice, an intermediate and an almost competent trainee, were evaluated with GRSs (OSATS and GOALS) and the independence-scaled procedural assessment by seven surgeons, three senior trainees and six scrub nurses. Participants received a short introduction to the GRSs and independence-scaled procedural assessment before assessment. The validity was estimated with the Friedman and Wilcoxon test and the reliability with the intra-class correlation coefficient (ICC). A questionnaire was used to evaluate user opinion. Independence-scaled procedural assessment and GRS scores improved significantly with surgical experience (OSATS p = 0.001, GOALS p < 0.001, independence-scaled procedural assessment p < 0.001). The ICCs of the OSATS, GOALS and independence-scaled procedural assessment were 0.78, 0.74 and 0.84, respectively, among surgeons. The ICCs increased when the ratings of scrub nurses were added to those of the surgeons. The independence-scaled procedural assessment was not considered more of an administrative burden than the GRSs (p = 0.692). A procedural assessment created by combining procedural key steps to an independence scale is a valid, reliable and acceptable assessment instrument in surgery. In contrast to the GRSs, the reliability of the independence-scaled procedural assessment exceeded the threshold of 0.8, indicating that it can also be used for summative assessment. It furthermore seems that scrub nurses can assess the operative competence of surgical trainees.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-01

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

  5. RELIABILITY AND VALIDITY OF SUBJECTIVE ASSESSMENT OF LUMBAR LORDOSIS IN CONVENTIONAL RADIOGRAPHY.

    Science.gov (United States)

    Ruhinda, E; Byanyima, R K; Mugerwa, H

    2014-10-01

    Reliability and validity studies of different lumbar curvature analysis and measurement techniques have been documented however there is limited literature on the reliability and validity of subjective visual analysis. Radiological assessment of lumbar lordotic curve aids in early diagnosis of conditions even before neurologic changes set in. To ascertain the level of reliability and validity of subjective assessment of lumbar lordosis in conventional radiography. A blinded, repeated-measures diagnostic test was carried out on lumbar spine x-ray radiographs. Radiology Department at Joint Clinical Research Centre (JCRC), Mengo-Kampala-Uganda. Seventy (70) lateral lumbar x-ray films were used for this study and were obtained from the archive of JCRC radiology department at Butikiro house, Mengo-Kampala. Poor observer agreement, both inter- and intra-observer, with kappa values of 0.16 was found. Inter-observer agreement was poorer than intra-observer agreement. Kappa values significantly rose when the lumbar lordosis was clustered into four categories without grading each abnormality. The results confirm that subjective assessment of lumbar lordosis has low reliability and validity. Film quality has limited influence on the observer reliability. This study further shows that fewer scale categories of lordosis abnormalities produce better observer reliability.

  6. Balance Assessment in Sports-Related Concussion: Evaluating Test-Retest Reliability of the Equilibrate System.

    Science.gov (United States)

    Odom, Mitchell J; Lee, Young M; Zuckerman, Scott L; Apple, Rachel P; Germanos, Theodore; Solomon, Gary S; Sills, Allen K

    2016-01-01

    This study evaluated the test-retest reliability of a novel computer-based, portable balance assessment tool, the Equilibrate System (ES), used to diagnose sports-related concussion. Twenty-seven students participated in ES testing consisting of three sessions over 4 weeks. The modified Balance Error Scoring System was performed. For each participant, test-retest reliability was established using the intraclass correlation coefficient (ICC). The ES test-retest reliability from baseline to week 2 produced an ICC value of 0.495 (95% CI, 0.123-0.745). Week 2 testing produced ICC values of 0.602 (95% CI, 0.279-0.803) and 0.610 (95% CI, 0.299-0.804), respectively. All other single measures test-retest reliability values produced poor ICC values. Same-day ES testing showed fair to good test-retest reliability while interweek measures displayed poor to fair test-retest reliability. Testing conditions should be controlled when using computerized balance assessment methods. ES testing should only be used as a part of a comprehensive assessment.

  7. Use of reliability engineering tools in safety and risk assessment of nuclear facilities

    Energy Technology Data Exchange (ETDEWEB)

    Raso, Amanda Laureano; Vasconcelos, Vanderley de; Marques, Raíssa Oliveira; Soares, Wellington Antonio; Mesquita, Amir Zacarias, E-mail: amandaraso@hotmail.com, E-mail: vasconv@cdtn.br, E-mail: raissaomarques@gmail.com, E-mail: soaresw@cdtn.br, E-mail: amir@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Serviço de Tecnologia de Reatores

    2017-07-01

    Safety, reliability and availability are fundamental criteria in design, construction and operation of nuclear facilities, as nuclear power plants. Deterministic and probabilistic risk assessments of such facilities are required by regulatory authorities in order to meet licensing regulations, contributing to assure safety, as well as reduce costs and environmental impacts. Probabilistic Risk Assessment has become an important part of licensing requirements of the nuclear power plants in Brazil and in the world. Risk can be defined as a qualitative and/or quantitative assessment of accident sequence frequencies (or probabilities) and their consequences. Risk management is a systematic application of management policies, procedures and practices to identify, analyze, plan, implement, control, communicate and document risks. Several tools and computer codes must be combined, in order to estimate both probabilities and consequences of accidents. Event Tree Analysis (ETA), Fault Tree Analysis (FTA), Reliability Block Diagrams (RBD), and Markov models are examples of evaluation tools that can support the safety and risk assessment for analyzing process systems, identifying potential accidents, and estimating consequences. Because of complexity of such analyzes, specialized computer codes are required, such as the reliability engineering software develop by Reliasoft® Corporation. BlockSim (FTA, RBD and Markov models), RENO (ETA and consequence assessment), Weibull++ (life data and uncertainty analysis), and Xfmea (qualitative risk assessment) are some codes that can be highlighted. This work describes an integrated approach using these tools and software to carry out reliability, safety, and risk assessment of nuclear facilities, as well as, and application example. (author)

  8. Use of reliability engineering tools in safety and risk assessment of nuclear facilities

    International Nuclear Information System (INIS)

    Raso, Amanda Laureano; Vasconcelos, Vanderley de; Marques, Raíssa Oliveira; Soares, Wellington Antonio; Mesquita, Amir Zacarias

    2017-01-01

    Safety, reliability and availability are fundamental criteria in design, construction and operation of nuclear facilities, as nuclear power plants. Deterministic and probabilistic risk assessments of such facilities are required by regulatory authorities in order to meet licensing regulations, contributing to assure safety, as well as reduce costs and environmental impacts. Probabilistic Risk Assessment has become an important part of licensing requirements of the nuclear power plants in Brazil and in the world. Risk can be defined as a qualitative and/or quantitative assessment of accident sequence frequencies (or probabilities) and their consequences. Risk management is a systematic application of management policies, procedures and practices to identify, analyze, plan, implement, control, communicate and document risks. Several tools and computer codes must be combined, in order to estimate both probabilities and consequences of accidents. Event Tree Analysis (ETA), Fault Tree Analysis (FTA), Reliability Block Diagrams (RBD), and Markov models are examples of evaluation tools that can support the safety and risk assessment for analyzing process systems, identifying potential accidents, and estimating consequences. Because of complexity of such analyzes, specialized computer codes are required, such as the reliability engineering software develop by Reliasoft® Corporation. BlockSim (FTA, RBD and Markov models), RENO (ETA and consequence assessment), Weibull++ (life data and uncertainty analysis), and Xfmea (qualitative risk assessment) are some codes that can be highlighted. This work describes an integrated approach using these tools and software to carry out reliability, safety, and risk assessment of nuclear facilities, as well as, and application example. (author)

  9. Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization

    Science.gov (United States)

    More, Sushant N.

    New insights into the inter-nucleon interactions, developments in many-body technology, and the surge in computational capabilities has led to phenomenal progress in low-energy nuclear physics in the past few years. Nonetheless, many calculations still lack a robust uncertainty quantification which is essential for making reliable predictions. In this work we investigate two distinct sources of uncertainty and develop ways to account for them. Harmonic oscillator basis expansions are widely used in ab-initio nuclear structure calculations. Finite computational resources usually require that the basis be truncated before observables are fully converged, necessitating reliable extrapolation schemes. It has been demonstrated recently that errors introduced from basis truncation can be taken into account by focusing on the infrared and ultraviolet cutoffs induced by a truncated basis. We show that a finite oscillator basis effectively imposes a hard-wall boundary condition in coordinate space. We accurately determine the position of the hard-wall as a function of oscillator space parameters, derive infrared extrapolation formulas for the energy and other observables, and discuss the extension of this approach to higher angular momentum and to other localized bases. We exploit the duality of the harmonic oscillator to account for the errors introduced by a finite ultraviolet cutoff. Nucleon knockout reactions have been widely used to study and understand nuclear properties. Such an analysis implicitly assumes that the effects of the probe can be separated from the physics of the target nucleus. This factorization between nuclear structure and reaction components depends on the renormalization scale and scheme, and has not been well understood. But it is potentially critical for interpreting experiments and for extracting process-independent nuclear properties. We use a class of unitary transformations called the similarity renormalization group (SRG) transformations to

  10. Reliability of Computerized Neurocognitive Tests for Concussion Assessment: A Meta-Analysis.

    Science.gov (United States)

    Farnsworth, James L; Dargo, Lucas; Ragan, Brian G; Kang, Minsoo

    2017-09-01

      Although widely used, computerized neurocognitive tests (CNTs) have been criticized because of low reliability and poor sensitivity. A systematic review was published summarizing the reliability of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) scores; however, this was limited to a single CNT. Expansion of the previous review to include additional CNTs and a meta-analysis is needed. Therefore, our purpose was to analyze reliability data for CNTs using meta-analysis and examine moderating factors that may influence reliability.   A systematic literature search (key terms: reliability, computerized neurocognitive test, concussion) of electronic databases (MEDLINE, PubMed, Google Scholar, and SPORTDiscus) was conducted to identify relevant studies.   Studies were included if they met all of the following criteria: used a test-retest design, involved at least 1 CNT, provided sufficient statistical data to allow for effect-size calculation, and were published in English.   Two independent reviewers investigated each article to assess inclusion criteria. Eighteen studies involving 2674 participants were retained. Intraclass correlation coefficients were extracted to calculate effect sizes and determine overall reliability. The Fisher Z transformation adjusted for sampling error associated with averaging correlations. Moderator analyses were conducted to evaluate the effects of the length of the test-retest interval, intraclass correlation coefficient model selection, participant demographics, and study design on reliability. Heterogeneity was evaluated using the Cochran Q statistic.   The proportion of acceptable outcomes was greatest for the Axon Sports CogState Test (75%) and lowest for the ImPACT (25%). Moderator analyses indicated that the type of intraclass correlation coefficient model used significantly influenced effect-size estimates, accounting for 17% of the variation in reliability.   The Axon Sports CogState Test, which

  11. Reliability Assessment of Cloud Computing Platform Based on Semiquantitative Information and Evidential Reasoning

    Directory of Open Access Journals (Sweden)

    Hang Wei

    2016-01-01

    Full Text Available A reliability assessment method based on evidential reasoning (ER rule and semiquantitative information is proposed in this paper, where a new reliability assessment architecture including four aspects with both quantitative data and qualitative knowledge is established. The assessment architecture is more objective in describing complex dynamic cloud computing environment than that in traditional method. In addition, the ER rule which has good performance for multiple attribute decision making problem is employed to integrate different types of the attributes in assessment architecture, which can obtain more accurate assessment results. The assessment results of the case study in an actual cloud computing platform verify the effectiveness and the advantage of the proposed method.

  12. An overview of the evolution of human reliability analysis in the context of probabilistic risk assessment

    International Nuclear Information System (INIS)

    Bley, Dennis C.; Lois, Erasmia; Kolaczkowski, Alan M.; Forester, John Alan; Wreathall, John; Cooper, Susan E.

    2009-01-01

    Since the Reactor Safety Study in the early 1970's, human reliability analysis (HRA) has been evolving towards a better ability to account for the factors and conditions that can lead humans to take unsafe actions and thereby provide better estimates of the likelihood of human error for probabilistic risk assessments (PRAs). The purpose of this paper is to provide an overview of recent reviews of operational events and advances in the behavioral sciences that have impacted the evolution of HRA methods and contributed to improvements. The paper discusses the importance of human errors in complex human-technical systems, examines why humans contribute to accidents and unsafe conditions, and discusses how lessons learned over the years have changed the perspective and approach for modeling human behavior in PRAs of complicated domains such as nuclear power plants. It is argued that it has become increasingly more important to understand and model the more cognitive aspects of human performance and to address the broader range of factors that have been shown to influence human performance in complex domains. The paper concludes by addressing the current ability of HRA to adequately predict human failure events and their likelihood

  13. An overview of the evolution of human reliability analysis in the context of probabilistic risk assessment.

    Energy Technology Data Exchange (ETDEWEB)

    Bley, Dennis C. (Buttonwood Consulting Inc., Oakton, VA); Lois, Erasmia (U.S. Nuclear Regulatory Commission, Washington, DC); Kolaczkowski, Alan M. (Science Applications International Corporation, Eugene, OR); Forester, John Alan; Wreathall, John (John Wreathall and Co., Dublin, OH); Cooper, Susan E. (U.S. Nuclear Regulatory Commission, Washington, DC)

    2009-01-01

    Since the Reactor Safety Study in the early 1970's, human reliability analysis (HRA) has been evolving towards a better ability to account for the factors and conditions that can lead humans to take unsafe actions and thereby provide better estimates of the likelihood of human error for probabilistic risk assessments (PRAs). The purpose of this paper is to provide an overview of recent reviews of operational events and advances in the behavioral sciences that have impacted the evolution of HRA methods and contributed to improvements. The paper discusses the importance of human errors in complex human-technical systems, examines why humans contribute to accidents and unsafe conditions, and discusses how lessons learned over the years have changed the perspective and approach for modeling human behavior in PRAs of complicated domains such as nuclear power plants. It is argued that it has become increasingly more important to understand and model the more cognitive aspects of human performance and to address the broader range of factors that have been shown to influence human performance in complex domains. The paper concludes by addressing the current ability of HRA to adequately predict human failure events and their likelihood.

  14. Validity and reliability of self-assessed physical fitness using visual analogue scales

    DEFF Research Database (Denmark)

    Strøyer, Jesper; Essendrop, Morten; Jensen, Lone Donbaek

    2007-01-01

    To test the validity and reliability of self-assessed physical fitness samples included healthcare assistants working at a hospital (women=170, men=17), persons working with physically and mentally handicapped patients (women=530, men= 123), and two separate groups of healthcare students (a) women...... except for flexibility among men. The reliability was moderate to good (ICC = .62 - .80). Self-assessed aerobic fitness, muscle strength, and flexibility showed moderate construct validity and moderate to good reliability using visual analogues.......=91 and men=5 and (b) women=159 and men=10. Five components of physical fitness were self-assessed by Visual Analogue Scales with illustrations and verbal anchors for the extremes: aerobic fitness, muscle strength, endurance, flexibility, and balance. Convergent and divergent validity were evaluated...

  15. The Development of Marine Accidents Human Reliability Assessment Approach: HEART Methodology and MOP Model

    OpenAIRE

    Ludfi Pratiwi Bowo; Wanginingastuti Mutmainnah; Masao Furusho

    2017-01-01

    Humans are one of the important factors in the assessment of accidents, particularly marine accidents. Hence, studies are conducted to assess the contribution of human factors in accidents. There are two generations of Human Reliability Assessment (HRA) that have been developed. Those methodologies are classified by the differences of viewpoints of problem-solving, as the first generation and second generation. The accident analysis can be determined using three techniques of analysis; sequen...

  16. Assessing reliability of fatigue indicator parameters for small crack growth via a probabilistic framework

    Science.gov (United States)

    Rovinelli, Andrea; Guilhem, Yoann; Proudhon, Henry; Lebensohn, Ricardo A.; Ludwig, Wolfgang; Sangid, Michael D.

    2017-06-01

    Microstructurally small cracks exhibit large variability in their fatigue crack growth rate. It is accepted that the inherent variability in microstructural features is related to the uncertainty in the growth rate. However, due to (i) the lack of cycle-by-cycle experimental data, (ii) the complexity of the short crack growth phenomenon, and (iii) the incomplete physics of constitutive relationships, only empirical damage metrics have been postulated to describe the short crack driving force metric (SCDFM) at the mesoscale level. The identification of the SCDFM of polycrystalline engineering alloys is a critical need, in order to achieve more reliable fatigue life prediction and improve material design. In this work, the first steps in the development of a general probabilistic framework are presented, which uses experimental result as an input, retrieves missing experimental data through crystal plasticity (CP) simulations, and extracts correlations utilizing machine learning and Bayesian networks (BNs). More precisely, experimental results representing cycle-by-cycle data of a short crack growing through a beta-metastable titanium alloy, VST-55531, have been acquired via phase and diffraction contrast tomography. These results serve as an input for FFT-based CP simulations, which provide the micromechanical fields influenced by the presence of the crack, complementing the information available from the experiment. In order to assess the correlation between postulated SCDFM and experimental observations, the data is mined and analyzed utilizing BNs. Results show the ability of the framework to autonomously capture relevant correlations and the equivalence in the prediction capability of different postulated SCDFMs for the high cycle fatigue regime.

  17. Training less-experienced faculty improves reliability of skills assessment in cardiac surgery.

    Science.gov (United States)

    Lou, Xiaoying; Lee, Richard; Feins, Richard H; Enter, Daniel; Hicks, George L; Verrier, Edward D; Fann, James I

    2014-12-01

    Previous work has demonstrated high inter-rater reliability in the objective assessment of simulated anastomoses among experienced educators. We evaluated the inter-rater reliability of less-experienced educators and the impact of focused training with a video-embedded coronary anastomosis assessment tool. Nine less-experienced cardiothoracic surgery faculty members from different institutions evaluated 2 videos of simulated coronary anastomoses (1 by a medical student and 1 by a resident) at the Thoracic Surgery Directors Association Boot Camp. They then underwent a 30-minute training session using an assessment tool with embedded videos to anchor rating scores for 10 components of coronary artery anastomosis. Afterward, they evaluated 2 videos of a different student and resident performing the task. Components were scored on a 1 to 5 Likert scale, yielding an average composite score. Inter-rater reliabilities of component and composite scores were assessed using intraclass correlation coefficients (ICCs) and overall pass/fail ratings with kappa. All components of the assessment tool exhibited improvement in reliability, with 4 (bite, needle holder use, needle angles, and hand mechanics) improving the most from poor (ICC range, 0.09-0.48) to strong (ICC range, 0.80-0.90) agreement. After training, inter-rater reliabilities for composite scores improved from moderate (ICC, 0.76) to strong (ICC, 0.90) agreement, and for overall pass/fail ratings, from poor (kappa = 0.20) to moderate (kappa = 0.78) agreement. Focused, video-based anchor training facilitates greater inter-rater reliability in the objective assessment of simulated coronary anastomoses. Among raters with less teaching experience, such training may be needed before objective evaluation of technical skills. Published by Elsevier Inc.

  18. Development of a quality-assessment tool for experimental bruxism studies: reliability and validity.

    Science.gov (United States)

    Dawson, Andreas; Raphael, Karen G; Glaros, Alan; Axelsson, Susanna; Arima, Taro; Ernberg, Malin; Farella, Mauro; Lobbezoo, Frank; Manfredini, Daniele; Michelotti, Ambra; Svensson, Peter; List, Thomas

    2013-01-01

    To combine empirical evidence and expert opinion in a formal consensus method in order to develop a quality-assessment tool for experimental bruxism studies in systematic reviews. Tool development comprised five steps: (1) preliminary decisions, (2) item generation, (3) face-validity assessment, (4) reliability and discriminitive validity assessment, and (5) instrument refinement. The kappa value and phi-coefficient were calculated to assess inter-observer reliability and discriminative ability, respectively. Following preliminary decisions and a literature review, a list of 52 items to be considered for inclusion in the tool was compiled. Eleven experts were invited to join a Delphi panel and 10 accepted. Four Delphi rounds reduced the preliminary tool-Quality-Assessment Tool for Experimental Bruxism Studies (Qu-ATEBS)- to 8 items: study aim, study sample, control condition or group, study design, experimental bruxism task, statistics, interpretation of results, and conflict of interest statement. Consensus among the Delphi panelists yielded good face validity. Inter-observer reliability was acceptable (k = 0.77). Discriminative validity was excellent (phi coefficient 1.0; P reviews of experimental bruxism studies, exhibits face validity, excellent discriminative validity, and acceptable inter-observer reliability. Development of quality assessment tools for many other topics in the orofacial pain literature is needed and may follow the described procedure.

  19. Proceeding of 35th domestic symposium on applications of structural reliability and risk assessment methods to nuclear power plants

    International Nuclear Information System (INIS)

    2005-06-01

    As the 35th domestic symposium of Atomic Energy Research Committee, the Japan Welding Engineering Society, the symposium was held titled as Applications of structural reliability/risk assessment methods to nuclear energy'. Six speakers gave lectures titled as 'Structural reliability and risk assessment methods', 'Risk-informed regulation of US nuclear energy and role of probabilistic risk assessment', 'Reliability and risk assessment methods in chemical plants', 'Practical structural design methods based on reliability in architectural and civil areas', 'Maintenance activities based on reliability in thermal power plants' and 'LWR maintenance strategies based on Probabilistic Fracture Mechanics'. (T. Tanaka)

  20. Reliability assessment for metallized film pulse capacitors with accelerated degradation test

    International Nuclear Information System (INIS)

    Zhao Jianyin; Liu Fang; Xi Wenjun; He Shaobo; Wei Xiaofeng

    2011-01-01

    The high energy density self-healing metallized film pulse capacitor has been applied to all kinds of laser facilities for their power conditioning systems, whose reliability is straightforward affected by the reliability level of capacitors. Reliability analysis of highly reliable devices, such as metallized film capacitors, is a challenge due to cost and time restriction. Accelerated degradation test provides a way to predict its life cost and time effectively. A model and analyses for accelerated degradation data of metallized film capacitors are described. Also described is a method for estimating the distribution of failure time. The estimation values of the unknown parameters in this model are 9.066 9 x 10 -8 and 0.022 1. Both the failure probability density function (PDF) and the cumulative distribution function (CDF) can be presented by this degradation failure model. Based on these estimation values and the PDF/CDF, the reliability model of the metallized film capacitors is obtained. According to the reliability model, the probability of the capacitors surviving to 20 000 shot is 0.972 4. (authors)

  1. Interrater and Intrarater Reliability of the Tuck Jump Assessment by Health Professionals of Varied Educational Backgrounds

    Directory of Open Access Journals (Sweden)

    Lisa A. Dudley

    2013-01-01

    Full Text Available Objective. The Tuck Jump Assessment (TJA, a clinical plyometric assessment, identifies 10 jumping and landing technique flaws. The study objective was to investigate TJA interrater and intrarater reliability with raters of different educational and clinical backgrounds. Methods. 40 participants were video recorded performing the TJA using published protocol and instructions. Five raters of varied educational and clinical backgrounds scored the TJA. Each score of the 10 technique flaws was summed for the total TJA score. Approximately one month later, 3 raters scored the videos again. Intraclass correlation coefficients determined interrater (5 and 3 raters for first and second session, resp. and intrarater (3 raters reliability. Results. Interrater reliability with 5 raters was poor (ICC = 0.47; 95% confidence intervals (CI 0.33–0.62. Interrater reliability between 3 raters who completed 2 scoring sessions improved from 0.52 (95% CI 0.35–0.68 for session one to 0.69 (95% CI 0.55–0.81 for session two. Intrarater reliability was poor to moderate, ranging from 0.44 (95% CI 0.22–0.68 to 0.72 (95% CI 0.55–0.84. Conclusion. Published protocol and training of raters were insufficient to allow consistent TJA scoring. There may be a learned effect with the TJA since interrater reliability improved with repetition. TJA instructions and training should be modified and enhanced before clinical implementation.

  2. Reliability assessment of aging structures subjected to gradual and shock deteriorations

    International Nuclear Information System (INIS)

    Wang, Cao; Zhang, Hao; Li, Quanwang

    2017-01-01

    Civil structures and infrastructure facilities are susceptible to deterioration posed by the effects of natural hazards and aggressive environmental conditions. These factors may increase the risk of service interruption of infrastructures, and should be taken into account when assessing the structural reliability during an infrastructure's service life. Modeling the resistance deterioration process reasonably is the basis for structural reliability analysis. In this paper, a novel model is developed for describing the deterioration of aging structures. The deterioration is a combination of two stochastic processes: the gradual deterioration posed by environmental effects and the shock deterioration caused by severe load attacks. The dependency of the deterioration magnitude on the load intensity is considered. The Gaussian copula function is employed to help construct the joint distribution of correlated random variables. Semi-analytical methods are developed to assess the structural failure time and the number of significant load events (shocks) to failure. Illustrative examples are presented to demonstrate the applicability of the proposed model in structural reliability analysis. Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability. - Highlights: • A new resistance deterioration model for aging structures is proposed. • Time-dependent reliability analysis methods incorporating the proposed deterioration model are developed. • Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability.

  3. Method for assessing software reliability of the document management system using the RFID technology

    Directory of Open Access Journals (Sweden)

    Kiedrowicz Maciej

    2016-01-01

    Full Text Available The deliberations presented in this study refer to the method for assessing software reliability of the docu-ment management system, using the RFID technology. A method for determining the reliability structure of the dis-cussed software, understood as the index vector for assessing reliability of its components, was proposed. The model of the analyzed software is the control transfer graph, in which the probability of activating individual components during the system's operation results from the so-called operational profile, which characterizes the actual working environment. The reliability structure is established as a result of the solution of a specific mathematical software task. The knowledge of the reliability structure of the software makes it possible to properly plan the time and finan-cial expenses necessary to build the software, which would meet the reliability requirements. The application of the presented method is illustrated by the number example, corresponding to the software reality of the RFID document management system.

  4. Reliabilities of mental rotation tasks: limits to the assessment of individual differences.

    Science.gov (United States)

    Hirschfeld, Gerrit; Thielsch, Meinald T; Zernikow, Boris

    2013-01-01

    Mental rotation tasks with objects and body parts as targets are widely used in cognitive neuropsychology. Even though these tasks are well established to study between-groups differences, the reliability on an individual level is largely unknown. We present a systematic study on the internal consistency and test-retest reliability of individual differences in mental rotation tasks comparing different target types and orders of presentations. In total n = 99 participants (n = 63 for the retest) completed the mental rotation tasks with hands, feet, faces, and cars as targets. Different target types were presented in either randomly mixed blocks or blocks of homogeneous targets. Across all target types, the consistency (split-half reliability) and stability (test-retest reliabilities) were good or acceptable both for intercepts and slopes. At the level of individual targets, only intercepts showed acceptable reliabilities. Blocked presentations resulted in significantly faster and numerically more consistent and stable responses. Mental rotation tasks-especially in blocked variants-can be used to reliably assess individual differences in global processing speed. However, the assessment of the theoretically important slope parameter for individual targets requires further adaptations to mental rotation tests.

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

    Directory of Open Access Journals (Sweden)

    Leonardo Dueñas-Osorio

    2012-06-01

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

  6. Reliability assessment of distribution system with the integration of renewable distributed generation

    International Nuclear Information System (INIS)

    Adefarati, T.; Bansal, R.C.

    2017-01-01

    Highlights: • Addresses impacts of renewable DG on the reliability of the distribution system. • Multi-objective formulation for maximizing the cost saving with integration of DG. • Uses Markov model to study the stochastic characteristics of the major components. • The investigation is done using modified RBTS bus test distribution system. • Proposed approach is useful for electric utilities to enhance the reliability. - Abstract: Recent studies have shown that renewable energy resources will contribute substantially to future energy generation owing to the rapid depletion of fossil fuels. Wind and solar energy resources are major sources of renewable energy that have the ability to reduce the energy crisis and the greenhouse gases emitted by the conventional power plants. Reliability assessment is one of the key indicators to measure the impact of the renewable distributed generation (DG) units in the distribution networks and to minimize the cost that is associated with power outage. This paper presents a comprehensive reliability assessment of the distribution system that satisfies the consumer load requirements with the penetration of wind turbine generator (WTG), electric storage system (ESS) and photovoltaic (PV). A Markov model is proposed to access the stochastic characteristics of the major components of the renewable DG resources as well as their influence on the reliability of a conventional distribution system. The results obtained from the case studies have demonstrated the effectiveness of using WTG, ESS and PV to enhance the reliability of the conventional distribution system.

  7. Assessment of Equipment Capability to Perform Reliably under Severe Accident Conditions

    International Nuclear Information System (INIS)

    2017-07-01

    The experience from the last 40 years has shown that severe accidents can subject electrical and instrumentation and control (I&C) equipment to environmental conditions exceeding the equipment’s original design basis assumptions. Severe accident conditions can then cause rapid degradation or damage to various degrees up to complete failure of such equipment. This publication provides the technical basis to consider when assessing the capability of electrical and I&C equipment to perform reliably during a severe accident. It provides examples of calculation tools to determine the environmental parameters as well as examples and methods that Member States can apply to assess equipment reliability.

  8. Phd study of reliability and validity: One step closer to a standardized music therapy assessment model

    DEFF Research Database (Denmark)

    Jacobsen, Stine Lindahl

    The paper will present a phd study concerning reliability and validity of music therapy assessment model “Assessment of Parenting Competences” (APC) in the area of families with emotionally neglected children. This study had a multiple strategy design with a philosophical base of critical realism...... and pragmatism. The fixed design for this study was a between and within groups design in testing the APCs reliability and validity. The two different groups were parents with neglected children and parents with non-neglected children. The flexible design had a multiple case study strategy specifically...

  9. Reliability and Validity of 3 Methods of Assessing Orthopedic Resident Skill in Shoulder Surgery.

    Science.gov (United States)

    Bernard, Johnathan A; Dattilo, Jonathan R; Srikumaran, Uma; Zikria, Bashir A; Jain, Amit; LaPorte, Dawn M

    Traditional measures for evaluating resident surgical technical skills (e.g., case logs) assess operative volume but not level of surgical proficiency. Our goal was to compare the reliability and validity of 3 tools for measuring surgical skill among orthopedic residents when performing 3 open surgical approaches to the shoulder. A total of 23 residents at different stages of their surgical training were tested for technical skill pertaining to 3 shoulder surgical approaches using the following measures: Objective Structured Assessment of Technical Skills (OSATS) checklists, the Global Rating Scale (GRS), and a final pass/fail assessment determined by 3 upper extremity surgeons. Adverse events were recorded. The Cronbach α coefficient was used to assess reliability of the OSATS checklists and GRS scores. Interrater reliability was calculated with intraclass correlation coefficients. Correlations among OSATS checklist scores, GRS scores, and pass/fail assessment were calculated with Spearman ρ. Validity of OSATS checklists was determined using analysis of variance with postgraduate year (PGY) as a between-subjects factor. Significance was set at p shoulder approaches. Checklist scores showed superior interrater reliability compared with GRS and subjective pass/fail measurements. GRS scores were positively correlated across training years. The incidence of adverse events was significantly higher among PGY-1 and PGY-2 residents compared with more experienced residents. OSATS checklists are a valid and reliable assessment of technical skills across 3 surgical shoulder approaches. However, checklist scores do not measure quality of technique. Documenting adverse events is necessary to assess quality of technique and ultimate pass/fail status. Multiple methods of assessing surgical skill should be considered when evaluating orthopedic resident surgical performance. Copyright © 2016 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights

  10. Isometric abdominal wall muscle strength assessment in individuals with incisional hernia: a prospective reliability study

    DEFF Research Database (Denmark)

    Jensen, K. K.; Kjær, Michael; Jorgensen, L. N.

    2016-01-01

    Purpose To determine the reliability of measurements obtained by the Good Strength dynamometer, determining isometric abdominal wall and back muscle strength in patients with ventral incisional hernia (VIH) and healthy volunteers with an intact abdominal wall. Methods Ten patients with VIH and ten...... and extension showed excellent test–retest reliability for both patients with VIH (ICC 0.91 and 0.99) and healthy controls (ICC 0.97 and 0.96). Bland and Altman plots showed that no systematic bias was present for neither truncal flexion nor extension when assessing reliability. For patients with VIH...... and IPAQ was found. Conclusions The Good Strength dynamometer provided a reliable, low-cost measure of truncal flexion and extension in patients with VIH....

  11. The multiple sclerosis work difficulties questionnaire: translation and cross-cultural adaptation to Turkish and assessment of validity and reliability.

    Science.gov (United States)

    Kahraman, Turhan; Özdoğar, Asiye Tuba; Honan, Cynthia Alison; Ertekin, Özge; Özakbaş, Serkan

    2018-05-09

    To linguistically and culturally adapt the Multiple Sclerosis Work Difficulties Questionnaire-23 (MSWDQ-23) for use in Turkey, and to examine its reliability and validity. Following standard forward-back translation of the MSWDQ-23, it was administered to 124 people with multiple sclerosis (MS). Validity was evaluated using related outcome measures including those related to employment status and expectations, disability level, fatigue, walking, and quality of life. Randomly selected participants were asked to complete the MSWDQ-23 again to assess test-retest reliability. Confirmatory factor analysis on the MSWDQ-23 demonstrated a good fit for the data, and the internal consistency of each subscale was excellent. The test-retest reliability for the total score, psychological/cognitive barriers, physical barriers, and external barriers subscales were high. The MSWDQ-23 and its subscales were positively correlated with the employment, disability level, walking, and fatigue outcome measures. This study suggests that the Turkish version of MSWDQ-23 has high reliability and adequate validity, and it can be used to determine the difficulties faced by people with multiple sclerosis in workplace. Moreover, the study provides evidence about the test-retest reliability of the questionnaire. Implications for rehabilitation Multiple sclerosis affects young people of working age. Understanding work-related problems is crucial to enhance people with multiple sclerosis likelihood of maintaining their job. The Multiple Sclerosis Work Difficulties Questionnaire-23 (MSWDQ-23) is a valid and reliable measure of perceived workplace difficulties in people with multiple sclerosis: we presented its validation to Turkish. Professionals working in the field of vocational rehabilitation may benefit from using the MSWDQ-23 to predict the current work outcomes and future employment expectations.

  12. Reliability and Validity Evidence of Multiple Balance Assessments in Athletes With a Concussion

    Science.gov (United States)

    Murray, Nicholas; Salvatore, Anthony; Powell, Douglas; Reed-Jones, Rebecca

    2014-01-01

    Context: An estimated 300 000 sport-related concussion injuries occur in the United States annually. Approximately 30% of individuals with concussions experience balance disturbances. Common methods of balance assessment include the Clinical Test of Sensory Organization and Balance (CTSIB), the Sensory Organization Test (SOT), the Balance Error Scoring System (BESS), and the Romberg test; however, the National Collegiate Athletic Association recommended the Wii Fit as an alternative measure of balance in athletes with a concussion. A central concern regarding the implementation of the Wii Fit is whether it is reliable and valid for measuring balance disturbance in athletes with concussion. Objective: To examine the reliability and validity evidence for the CTSIB, SOT, BESS, Romberg test, and Wii Fit for detecting balance disturbance in athletes with a concussion. Data Sources: Literature considered for review included publications with reliability and validity data for the assessments of balance (CTSIB, SOT, BESS, Romberg test, and Wii Fit) from PubMed, PsycINFO, and CINAHL. Data Extraction: We identified 63 relevant articles for consideration in the review. Of the 63 articles, 28 were considered appropriate for inclusion and 35 were excluded. Data Synthesis: No current reliability or validity information supports the use of the CTSIB, SOT, Romberg test, or Wii Fit for balance assessment in athletes with a concussion. The BESS demonstrated moderate to high reliability (interclass correlation coefficient = 0.87) and low to moderate validity (sensitivity = 34%, specificity = 87%). However, the Romberg test and Wii Fit have been shown to be reliable tools in the assessment of balance in Parkinson patients. Conclusions: The BESS can evaluate balance problems after a concussion. However, it lacks the ability to detect balance problems after the third day of recovery. Further investigation is needed to establish the use of the CTSIB, SOT, Romberg test, and Wii Fit for

  13. Validity and reliability of a nutrition knowledge survey for assessment in elementary school children.

    Science.gov (United States)

    Gower, Jared R; Moyer-Mileur, Laurie J; Wilkinson, Robert D; Slater, Hillarie; Jordan, Kristine C

    2010-03-01

    Limited surveys are available to assess the nutrition knowledge of children. The goals of this study were to test the validity and reliability of a computer nutrition knowledge survey for elementary school students and to evaluate the impact of the "Fit Kids 'r' Healthy Kids" nutrition intervention via the knowledge survey. During survey development, a sample (n=12) of health educators, elementary school teachers, and registered dietitians assessed the survey. The target population consisted of first- through fourth-grade students from Salt Lake City, UT, metropolitan area schools. Participants were divided into reliability (n=68), intervention (n=74), and control groups (n=59). The reliability group took the survey twice (2 weeks apart); the intervention and control groups also took the survey twice, but at pre- and post-intervention (4 weeks later). Only students from the intervention group participated in four weekly nutrition classes. Reliability was assessed by Pearson's correlation coefficients for knowledge scores. Results demonstrated appropriate content validity, as indicated by expert peer ratings. Test-retest reliability correlations were found to be significant for the overall survey (r=0.54; PNutrition knowledge was assessed upon program completion with paired samples t tests. Students from the intervention group demonstrated improvement in nutrition knowledge (12.2+/-1.9 to 13.5+/-1.6; Pnutrition survey demonstrated content validity and test-retest reliability for first- through fourth-grade elementary school children. Also, the study results imply that the Fit Kids 'r' Healthy Kids intervention promoted gains in nutrition knowledge. Overall, the computer survey shows promise as an appealing medium for assessing nutrition knowledge in children. Copyright 2010 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

  14. Reliability and validity evidence of multiple balance assessments in athletes with a concussion.

    Science.gov (United States)

    Murray, Nicholas; Salvatore, Anthony; Powell, Douglas; Reed-Jones, Rebecca

    2014-01-01

    An estimated 300 000 sport-related concussion injuries occur in the United States annually. Approximately 30% of individuals with concussions experience balance disturbances. Common methods of balance assessment include the Clinical Test of Sensory Organization and Balance (CTSIB), the Sensory Organization Test (SOT), the Balance Error Scoring System (BESS), and the Romberg test; however, the National Collegiate Athletic Association recommended the Wii Fit as an alternative measure of balance in athletes with a concussion. A central concern regarding the implementation of the Wii Fit is whether it is reliable and valid for measuring balance disturbance in athletes with concussion. To examine the reliability and validity evidence for the CTSIB, SOT, BESS, Romberg test, and Wii Fit for detecting balance disturbance in athletes with a concussion. Literature considered for review included publications with reliability and validity data for the assessments of balance (CTSIB, SOT, BESS, Romberg test, and Wii Fit) from PubMed, PsycINFO, and CINAHL. We identified 63 relevant articles for consideration in the review. Of the 63 articles, 28 were considered appropriate for inclusion and 35 were excluded. No current reliability or validity information supports the use of the CTSIB, SOT, Romberg test, or Wii Fit for balance assessment in athletes with a concussion. The BESS demonstrated moderate to high reliability (interclass correlation coefficient = 0.87) and low to moderate validity (sensitivity = 34%, specificity = 87%). However, the Romberg test and Wii Fit have been shown to be reliable tools in the assessment of balance in Parkinson patients. The BESS can evaluate balance problems after a concussion. However, it lacks the ability to detect balance problems after the third day of recovery. Further investigation is needed to establish the use of the CTSIB, SOT, Romberg test, and Wii Fit for assessing balance in athletes with concussions.

  15. Reliability of Lactation Assessment Tools Applied to Overweight and Obese Women.

    Science.gov (United States)

    Chapman, Donna J; Doughty, Katherine; Mullin, Elizabeth M; Pérez-Escamilla, Rafael

    2016-05-01

    The interrater reliability of lactation assessment tools has not been evaluated in overweight/obese women. This study aimed to compare the interrater reliability of 4 lactation assessment tools in this population. A convenience sample of 45 women (body mass index > 27.0) was videotaped while breastfeeding (twice daily on days 2, 4, and 7 postpartum). Three International Board Certified Lactation Consultants independently rated each videotaped session using 4 tools (Infant Breastfeeding Assessment Tool [IBFAT], modified LATCH [mLATCH], modified Via Christi [mVC], and Riordan's Tool [RT]). For each day and tool, we evaluated interrater reliability with 1-way repeated-measures analyses of variance, intraclass correlation coefficients (ICCs), and percentage absolute agreement between raters. Analyses of variance showed significant differences between raters' scores on day 2 (all scales) and day 7 (RT). Intraclass correlation coefficient values reflected good (mLATCH) to excellent reliability (IBFAT, mVC, and RT) on days 2 and 7. All day 4 ICCs reflected good reliability. The ICC for mLATCH was significantly lower than all others on day 2 and was significantly lower than IBFAT (day 7). Percentage absolute interrater agreement for scale components ranged from 31% (day 2: observable swallowing, RT) to 92% (day 7: IBFAT, fixing; and mVC, latch time). Swallowing scores on all scales had the lowest levels of interrater agreement (31%-64%). We demonstrated differences in the interrater reliability of 4 lactation assessment tools when applied to overweight/obese women, with the lowest values observed on day 4. Swallowing assessment was particularly unreliable. Researchers and clinicians using these scales should be aware of the differences in their psychometric behavior. © The Author(s) 2015.

  16. Lower limb spasticity assessment using an inertial sensor: a reliability study

    International Nuclear Information System (INIS)

    Sterpi, I; Colombo, R; Caroli, A; Meazza, E; Maggioni, G; Pistarini, C

    2013-01-01

    Spasticity is a common motor impairment in patients with neurological disorders that can prevent functional recovery after rehabilitation. In the clinical setting, its assessment is carried out using standardized clinical scales. The aim of this study was to verify the applicability of inertial sensors for an objective measurement of quadriceps spasticity and evaluate its test–retest and inter-rater reliability during the implementation of the Wartenberg pendulum test. Ten healthy subjects and 11 patients in vegetative state with severe brain damage were enrolled in this study. Subjects were evaluated three times on three consecutive days. The test–retest reliability of measurement was assessed in the first two days. The third day was devoted to inter-rater reliability assessment. In addition, the lower limb muscle tone was bilaterally evaluated at the knee joint by the modified Ashworth scale. The factorial ANOVA analysis showed that the implemented method allowed us to discriminate between healthy and pathological conditions. The fairly low SEM and high ICC values obtained for the pendulum parameters indicated a good test–retest and inter-rater reliability of measurement. This study shows that an inertial sensor can be reliably used to characterize leg kinematics during the Wartenberg pendulum test and provide quantitative evaluation of quadriceps spasticity. (paper)

  17. Reliability of the Alzheimer's disease assessment scale (ADAS-Cog) in longitudinal studies.

    Science.gov (United States)

    Khan, Anzalee; Yavorsky, Christian; DiClemente, Guillermo; Opler, Mark; Liechti, Stacy; Rothman, Brian; Jovic, Sofija

    2013-11-01

    Considering the scarcity of longitudinal assessments of reliability, there is need for a more precise understanding of cognitive decline in Alzheimer's Disease (AD). The primary goal was to assess longitudinal changes in inter-rater reliability, test retest reliability and internal consistency of scores of the ADAS-Cog. 2,618 AD subjects were enrolled in seven randomized, double-blind, placebo-controlled, multicenter-trials from 1986 to 2009. Reliability, internal-consistency and cross-sectional analysis of ADAS-Cog and MMSE across seven visits were examined. Intra-class correlation (ICC) for ADAS-Cog was moderate to high supporting their reliability. Absolute Agreement ICCs 0.392 (Visit-7) to 0.806 (Visit-2) showed a progressive decrease in correlations across time. Item analysis revealed a decrease in item correlations, with the lowest correlations for Visit 7 for Commands (ICC=0.148), Comprehension (ICC=0.092), Spoken Language (ICC=0.044). Suitable assessment of AD treatments is maintained through accurate measurement of clinically significant outcomes. Targeted rater education ADAS-Cog items over-time can improve ability to administer and score the scale.

  18. Wii Balance Board: Reliability and Clinical Use in Assessment of Balance in Healthy Elderly Women.

    Science.gov (United States)

    Monteiro-Junior, Renato Sobral; Ferreira, Arthur Sá; Puell, Vivian Neiva; Lattari, Eduardo; Machado, Sérgio; Otero Vaghetti, César Augusto; da Silva, Elirez Bezerra

    2015-01-01

    Force plate is considered gold standard tool to assess body balance. However the Wii Balance Board (WBB) platform is a trustworthy equipment to assess stabilometric components in young people. Thus, we aim to examine the reliability of measures of center of pressure with WBB in healthy elderly women. Twenty one healthy and physically active women were enrolled in the study (age: 64 ± 7 years; body mass index: 29 ± 5 kg/m2. The WBB was used to assess the center of pressure measures in the individuals. Pressure was linearly applied to different points to test the platform precision. Three assessments were performed, with two of them being held on the same day at a 5- to 10-minute interval, and the third one was performed 48 h later. A linear regression analysis was used to find out linearity, while the intraclass correlation coefficient was used to assess reliability. The platform precision was adequate (R2 = 0.997, P = 0.01). Center of pressure measures showed an excellent reliability (all intraclass correlation coefficient values were > 0.90; p < 0.01). The WBB is a precise and reliable tool of body stability quantitative measure in healthy active elderly women and its use should be encouraged in clinical settings.

  19. Reliability of magnetic resonance imaging assessment of rotator cuff: the ROW study.

    Science.gov (United States)

    Jain, Nitin B; Collins, Jamie; Newman, Joel S; Katz, Jeffrey N; Losina, Elena; Higgins, Laurence D

    2015-03-01

    Physiatrists encounter patients with rotator cuff disorders, and imaging is frequently an important component of their diagnostic assessment. However, there is a paucity of literature on the reliability of magnetic resonance imaging (MRI) assessment between shoulder specialists and musculoskeletal radiologists. We assessed inter- and intrarater reliability of MRI characteristics of the rotator cuff. Cross-sectional secondary analyses in a prospective cohort study. Academic tertiary care centers. Subjects with shoulder pain were recruited from orthopedic and physiatry clinics. Two shoulder-fellowship-trained physicians (a physiatrist and a shoulder surgeon) jointly performed a blinded composite MRI review by consensus of 31 subjects with shoulder pain. Subsequently, MRI was reviewed by one fellowship-trained musculoskeletal radiologist. We calculated the Cohen kappa coefficients and percentage agreement among the 2 reviews (composite review of 2 shoulder specialists versus that of the musculoskeletal radiologist). Intrarater reliability was assessed among the shoulder specialists by performing a repeated blinded composite MRI review. In addition to this repeated composite review, only one of the physiatry shoulder specialists performed an additional review. Interrater reliability (shoulder specialists versus musculoskeletal radiologist) was substantial for the presence or absence of tear (kappa 0.90 [95% confidence interval {CI}, 0.72-1.00]), tear thickness (kappa 0.84 [95% CI, 0.70-0.99]), longitudinal size of tear (kappa 0.75 [95% CI, 0.44-1.00]), fatty infiltration (kappa 0.62 [95% CI, 0.45-0.79]), and muscle atrophy (kappa 0.68 [95% CI, 0.50-0.86]). There was only fair interrater reliability of the transverse size of tear (kappa 0.20 [95% CI, 0.00-0.51]). The kappa for intrarater reliability was high for tear thickness (0.88 [95% CI, 0.72-1.00]), longitudinal tear size (0.61 [95% CI, 0.22-0.99]), fatty infiltration (0.89 [95% CI, 0.80,-0.98]), and muscle atrophy

  20. The Outcome and Assessment Information Set (OASIS): A Review of Validity and Reliability

    Science.gov (United States)

    O’CONNOR, MELISSA; DAVITT, JOAN K.

    2015-01-01

    The Outcome and Assessment Information Set (OASIS) is the patient-specific, standardized assessment used in Medicare home health care to plan care, determine reimbursement, and measure quality. Since its inception in 1999, there has been debate over the reliability and validity of the OASIS as a research tool and outcome measure. A systematic literature review of English-language articles identified 12 studies published in the last 10 years examining the validity and reliability of the OASIS. Empirical findings indicate the validity and reliability of the OASIS range from low to moderate but vary depending on the item studied. Limitations in the existing research include: nonrepresentative samples; inconsistencies in methods used, items tested, measurement, and statistical procedures; and the changes to the OASIS itself over time. The inconsistencies suggest that these results are tentative at best; additional research is needed to confirm the value of the OASIS for measuring patient outcomes, research, and quality improvement. PMID:23216513

  1. Statistical reliability assessment of UT round-robin test data for piping welds

    International Nuclear Information System (INIS)

    Kim, H.M.; Park, I.K.; Park, U.S.; Park, Y.W.; Kang, S.C.; Lee, J.H.

    2004-01-01

    Ultrasonic NDE is one of important technologies in the life-time maintenance of nuclear power plant. Ultrasonic inspection system is consisted of the operator, equipment and procedure. The reliability of ultrasonic inspection system is affected by its ability. The performance demonstration round robin was conducted to quantify the capability of ultrasonic inspection for in-service. Several teams employed procedures that met or exceeded with ASME sec. XI code requirements detected the piping of nuclear power plant with various cracks to evaluate the capability of detection and sizing. In this paper, the statistical reliability assessment of ultrasonic nondestructive inspection data using probability of detection (POD) is presented. The result of POD using logistic model was useful to the reliability assessment for the NDE hit or miss data. (orig.)

  2. Comparative availability and reliability assessment of design options for the secondary sodium loops of the EFR

    International Nuclear Information System (INIS)

    Pamme, H.

    1989-01-01

    The EFR (European Fast Reactor) project has entered a conceptual study period where different design alternatives are compared concerning feasibility, safety and economic aspects. This paper describes a comparative probabilistic availability and reliability assessment of alternative design options for the secondary sodium loops. These loops will provide heat transfer from the reactor pool to the water-steam (power generating) side. So a high operational availability of the secondary loops during plant lifetime is essential for economic power generation. Additionally a high reliability is required to fulfill the operational decay heat removal function in case of a reactor trip. Availabilities and reliabilities of the different options were assessed using failure mode and effect analysis and the fault tree method. (orig.)

  3. A set of key questions to assess the stress among bank employees and its reliability

    Directory of Open Access Journals (Sweden)

    Alice Mannocci

    2017-03-01

    Full Text Available The aims of the present study are: to realize a tool, clear and helpful, to assess the occupational distress level in bank employees in Italy; secondly to assess the reliability of the tool. Eight sentences were considered after a consensus meeting that involved different professional figures. 70 questionnaires were collected. The overall Cronbach’s alpha was 0.596, a sufficient reliability was found. The elimination of one sentences (“I haven’t time to dedicate myself to my hobbies/activities/stuff” increases alpha’s value from 0.596 to 0.620, and thus reach fully sufficient score. The claim “The pace of change on work place exceeds my capacity for adaptation” maximises the change of the level of reliability (Inter item Correlation = 0.528.

  4. Department of Defense need for a micro-electromechanical systems (MEMS) reliability assessment program

    Science.gov (United States)

    Zunino, James L., III; Skelton, Donald

    2005-01-01

    As the United States (U.S.) Army transforms into a lighter, more lethal, and more agile force, the technologies that support both legacy and emerging weapon systems must decrease in size while increasing in intelligence. Micro-electromechanical systems (MEMS) are one such technology that the Army as well as entire DOD will heavily rely on in achieving these objectives. Current and future military applications of MEMS devices include safety and arming devices, guidance systems, sensors/detectors, inertial measurement units, tracking devices, radio frequency devices, wireless radio frequency identification (RFID), etc. Even though the reliance on MEMS devices has been increasing, there have been no studies performed to determine their reliability and failure mechanisms. Furthermore, no standardized test protocols exist for assessing reliability. Accordingly, the U.S. Army Corrosion Office at Picatinny, NJ has initiated the MEMS Reliability Assessment Program to address this issue.

  5. Reliability of risk assessment measures used in sexually violent predator proceedings.

    Science.gov (United States)

    Miller, Cailey S; Kimonis, Eva R; Otto, Randy K; Kline, Suzonne M; Wasserman, Adam L

    2012-12-01

    The field interrater reliability of three assessment tools frequently used by mental health professionals when evaluating sex offenders' risk for reoffending--the Psychopathy Checklist-Revised (PCL-R), the Minnesota Sex Offender Screening Tool-Revised (MnSOST-R) and the Static-99-was examined within the context of sexually violent predator program proceedings. Rater agreement was highest for the Static--99 (intraclass correlation coefficient [ICC₁] = .78) and lowest for the PCL-R (ICC₁ = .60; MnSOST-R ICC₁ = .74), although all instruments demonstrated lower field reliability than that reported in their test manuals. Findings raise concerns about the reliability of risk assessment tools that are used to inform judgments of risk in high-stake sexually violent predator proceedings. Implications for future research and suggestions for improving evaluator training to increase accuracy when informing legal decision making are discussed.

  6. Accuracy and Reliability of Peer Assessment of Athletic Training Psychomotor Laboratory Skills

    Science.gov (United States)

    Marty, Melissa C.; Henning, Jolene M.; Willse, John T.

    2010-01-01

    Abstract Context: Peer assessment is defined as students judging the level or quality of a fellow student's understanding. No researchers have yet demonstrated the accuracy or reliability of peer assessment in athletic training education. Objective: To determine the accuracy and reliability of peer assessment of athletic training students' psychomotor skills. Design: Cross-sectional study. Setting: Entry-level master's athletic training education program. Patients or Other Participants: First-year (n  =  5) and second-year (n  =  8) students. Main Outcome Measure(s): Participants evaluated 10 videos of a peer performing 3 psychomotor skills (middle deltoid manual muscle test, Faber test, and Slocum drawer test) on 2 separate occasions using a valid assessment tool. Accuracy of each peer-assessment score was examined through percentage correct scores. We used a generalizability study to determine how reliable athletic training students were in assessing a peer performing the aforementioned skills. Decision studies using generalizability theory demonstrated how the peer-assessment scores were affected by the number of participants and number of occasions. Results: Participants had a high percentage of correct scores: 96.84% for the middle deltoid manual muscle test, 94.83% for the Faber test, and 97.13% for the Slocum drawer test. They were not able to reliably assess a peer performing any of the psychomotor skills on only 1 occasion. However, the ϕ increased (exceeding the 0.70 minimal standard) when 2 participants assessed the skill on 3 occasions (ϕ  =  0.79) for the Faber test, with 1 participant on 2 occasions (ϕ  =  0.76) for the Slocum drawer test, and with 3 participants on 2 occasions for the middle deltoid manual muscle test (ϕ  =  0.72). Conclusions: Although students did not detect all errors, they assessed their peers with an average of 96% accuracy. Having only 1 student assess a peer performing certain psychomotor skills was

  7. Accuracy and reliability of peer assessment of athletic training psychomotor laboratory skills.

    Science.gov (United States)

    Marty, Melissa C; Henning, Jolene M; Willse, John T

    2010-01-01

    Peer assessment is defined as students judging the level or quality of a fellow student's understanding. No researchers have yet demonstrated the accuracy or reliability of peer assessment in athletic training education. To determine the accuracy and reliability of peer assessment of athletic training students' psychomotor skills. Cross-sectional study. Entry-level master's athletic training education program. First-year (n  =  5) and second-year (n  =  8) students. Participants evaluated 10 videos of a peer performing 3 psychomotor skills (middle deltoid manual muscle test, Faber test, and Slocum drawer test) on 2 separate occasions using a valid assessment tool. Accuracy of each peer-assessment score was examined through percentage correct scores. We used a generalizability study to determine how reliable athletic training students were in assessing a peer performing the aforementioned skills. Decision studies using generalizability theory demonstrated how the peer-assessment scores were affected by the number of participants and number of occasions. Participants had a high percentage of correct scores: 96.84% for the middle deltoid manual muscle test, 94.83% for the Faber test, and 97.13% for the Slocum drawer test. They were not able to reliably assess a peer performing any of the psychomotor skills on only 1 occasion. However, the φ increased (exceeding the 0.70 minimal standard) when 2 participants assessed the skill on 3 occasions (φ  =  0.79) for the Faber test, with 1 participant on 2 occasions (φ  =  0.76) for the Slocum drawer test, and with 3 participants on 2 occasions for the middle deltoid manual muscle test (φ  =  0.72). Although students did not detect all errors, they assessed their peers with an average of 96% accuracy. Having only 1 student assess a peer performing certain psychomotor skills was less reliable than having more than 1 student assess those skills on more than 1 occasion. Peer assessment of psychomotor skills

  8. Reliability and Lifetime Prediction of Remote Phosphor Plates in Solid-State Lighting Applications Using Accelerated Degradation Testing

    NARCIS (Netherlands)

    Yazdan Mehr, M.; van Driel, W.D.; Zhang, G.Q.

    2015-01-01

    A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model,

  9. Reliability tests and guidelines for B-mode ultrasound assessment of central adiposity.

    Science.gov (United States)

    Stoner, Lee; Chinn, Victoria; Cornwall, Jon; Meikle, Grant; Page, Rachel; Lambrick, Danielle; Faulkner, James

    2015-11-01

    Ultrasound represents a validated and relatively inexpensive diagnostic device for assessing central adiposity; however, widespread adoption has been impeded by the lack of reliable standard operating procedures. To examine the reliability of, and describe guidelines for, ultrasound-derived recording of intra-abdominal fat thickness (IAT) and maximal preperitoneal fat thickness (PFT). Ultrasound scans were obtained from 20 adults (50% female, 26 ± 7 years, 24·5 kg/m(2) ) on three different mornings. IAT was assessed 2 cm above the umbilicus (transverse plane) measuring from linea alba to: (i) anterior aorta, (ii) posterior aorta and (iii) anterior aspect of the vertebral column. PFT was measured from linea alba to visceral peritoneum in (i) sagittal and (ii) transverse planes, immediately over and inferior to the xiphi-sternum, respectively. For IAT, the criterion intraclass correlation coefficient (ICC) of 0·75 was exceeded for measurements to anterior aorta (0·95), posterior aorta (0·94) and vertebra (0·96). The reliability coefficient expressed as a percentage of the mean (RC%) was lowest (better) for measurement to vertebrae (9·8%). For PFT, mean thickness was comparable for sagittal (1·74 cm) and transverse (1·76 cm) planes; ICC values were also comparable for both planes (0·98 vs. 0·98, respectively), as were RC% (7·5% vs. 7·1%, respectively). IAT assessments to the vertebra were marginally more reliable than those to other structures. While PFT assessments were equally reliable for both measurements planes, precise probe placement was easier for the sagittal plane. Based on these findings, guidelines for the reliable measurement of central adiposity using ultrasound are presented. © 2015 Stichting European Society for Clinical Investigation Journal Foundation.

  10. Assessing Academic Advising Outcomes Using Social Cognitive Theory: A Validity and Reliability Study

    Science.gov (United States)

    Erlich, Richard J.; Russ-Eft, Darlene F.

    2012-01-01

    The validity and reliability of three instruments, the "Counselor Rubric for Gauging Student Understanding of Academic Planning," micro-analytic questions, and the "Student Survey for Understanding Academic Planning," all based on social cognitive theory, were tested as means to assess self-efficacy and self-regulated learning in college academic…

  11. Validity and inter-observer reliability of subjective hand-arm vibration assessments

    NARCIS (Netherlands)

    Coenen, P.; Formanoy, M.; Douwes, M.; Bosch, T.; Kraker, H. de

    2014-01-01

    Exposure to mechanical vibrations at work (e.g., due to handling powered tools) is a potential occupational risk as it may cause upper extremity complaints. However, reliable and valid assessment methods for vibration exposure at work are lacking. Measuring hand-arm vibration objectively is often

  12. Estimating the Reliability of Aggregated and Within-Person Centered Scores in Ecological Momentary Assessment

    Science.gov (United States)

    Huang, Po-Hsien; Weng, Li-Jen

    2012-01-01

    A procedure for estimating the reliability of test scores in the context of ecological momentary assessment (EMA) was proposed to take into account the characteristics of EMA measures. Two commonly used test scores in EMA were considered: the aggregated score (AGGS) and the within-person centered score (WPCS). Conceptually, AGGS and WPCS represent…

  13. The inventory for déjà vu experiences assessment. Development, utility, reliability, and validity

    NARCIS (Netherlands)

    Sno, H. N.; Schalken, H. F.; de Jonghe, F.; Koeter, M. W.

    1994-01-01

    In this article the development, utility, reliability, and validity of the Inventory for Déjà vu Experiences Assessment (IDEA) are described. The IDEA is a 23-item self-administered questionnaire consisting of a general section of nine questions and qualitative section of 14 questions. The latter

  14. Analysis of the Reliability and Validity of a Mentor's Assessment for Principal Internships

    Science.gov (United States)

    Koonce, Glenn L.; Kelly, Michael D.

    2014-01-01

    In this study, researchers analyzed the reliability and validity of the mentor's assessment for principal internships at a university in the Southeast region of the United States. The results of the study yielded how trustworthy and dependable the instrument is and the effectiveness of the instrument in the current principal preparation program.…

  15. Examining the Reliability and Validity of the Effective Behavior Support Self-Assessment Survey

    Science.gov (United States)

    Solomon, Benjamin G.; Tobin, Kevin G.; Schutte, Gregory M.

    2015-01-01

    The Effective Behavior Support Self-Assessment Survey (SAS; Sugai, Horner, & Todd, 2003) is designed to measure perceived Positive Behavior Interventions and Supports (PBIS) implementation and identify priorities for improvement. Despite its longevity, little published research exists documenting its reliability or validity for these purposes.…

  16. Factor Structure and Reliability of Test Items for Saudi Teacher Licence Assessment

    Science.gov (United States)

    Alsadaawi, Abdullah Saleh

    2017-01-01

    The Saudi National Assessment Centre administers the Computer Science Teacher Test for teacher certification. The aim of this study is to explore gender differences in candidates' scores, and investigate dimensionality, reliability, and differential item functioning using confirmatory factor analysis and item response theory. The confirmatory…

  17. New application of dynamic reliability assessment of the mid-loop operation

    International Nuclear Information System (INIS)

    Moosung, Jae; Goon Cherl Park; Chang Hyun Chung

    1995-01-01

    This paper presents a new approach for assessing the dynamic reliability in a complex system such as a nuclear power plant. The method is applied to a dynamic analysis of the potential accident sequences that may occur during mid-loop operation

  18. Reliability of the craniocervical posture assessment: visual and angular measurements using photographs and radiographs.

    Science.gov (United States)

    Gadotti, Inae C; Armijo-Olivo, Susan; Silveira, Anelise; Magee, David

    2013-01-01

    The purposes of this study were to determine the intrarater and interrater reliability of the craniocervical posture in a sagittal view using quantitative measurements on photographs and radiographs and to determine the agreement of the visual assessment of posture between raters. One photograph and 1 radiograph of the sagittal craniocervical posture were simultaneously taken from 39 healthy female subjects. Three angles were measured on the photographs and 10 angles on the radiographs of 22 subjects using Alcimage software (Alcimage; Uberlândia, MG, Brazil). Two repeated measurements were performed by 2 raters. The measurements were compared within and between raters to test the intrarater and interrater reliability, respectively. Intraclass correlation coefficient and SEM were used. κ Agreement was calculated for the visual assessment of 39 subjects using photographs and radiographs between 2 raters. Good to excellent intrarater and interrater intraclass correlation coefficient values were found on both photographs and radiographs. Interrater SEM was large and clinically significant for cervical lordosis photogrammetry and for 1 angle measuring cervical lordosis on radiographs. Interrater κ agreement for the visual assessment using photographs was poor (κ = 0.37). The raters were reliable to measure angles in photographs and radiographs to quantify craniocervical posture with exception of 2 angles measuring lordosis of the cervical spine when compared between raters. The visual assessment of posture between raters was not reliable. © 2013. Published by National University of Health Sciences All rights reserved.

  19. Non-Parametric Bayesian Updating within the Assessment of Reliability for Offshore Wind Turbine Support Structures

    DEFF Research Database (Denmark)

    Ramirez, José Rangel; Sørensen, John Dalsgaard

    2011-01-01

    This work illustrates the updating and incorporation of information in the assessment of fatigue reliability for offshore wind turbine. The new information, coming from external and condition monitoring can be used to direct updating of the stochastic variables through a non-parametric Bayesian u...

  20. Reliability of the Life Satisfaction Questionnaire to assess patients with chronic musculoskeletal pain

    NARCIS (Netherlands)

    Boonstra, Anne M.; Reneman, Michiel F.; Posthumus, Jitze B.; Stewart, Roy E.; Schiphorst Preuper, Henrica R.

    The aim of this study was to determine the reliability of the Life Satisfaction Questionnaire, Dutch version (LSQ-DV), to assess chronic pain patients. The study was designed as test-retest. The setting was the general rehabilitation centre. There were 51 patients over 18 years of age, suffering