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

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)

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

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.

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

Reliability of the Filipino version of the Parent Satisfaction Scale: A preliminary study

OpenAIRE

Palad, Yves Y.; Madriaga, Gilbert O.

2014-01-01

Parent satisfaction is vital in improving the delivery of paediatric health care. However, there are no linguistically appropriate instruments that measure parent satisfaction among Filipino parents of children receiving occupational therapy, physical therapy, and speech pathology services. This study aimed to provide preliminary information about the reliability of the Filipino version of the Parent Satisfaction Scale (F-PSS). Research procedures included forward- and backward-translation of...

The Spanish version of the 2010 American College of Rheumatology Preliminary Diagnostic Criteria for fibromyalgia: reliability and validity assessment.

Science.gov (United States)

Casanueva, Benigno; García-Fructuoso, Ferrán; Belenguer, Rafael; Alegre, Cayetano; Moreno-Muelas, José V; Hernández, José L; Pina, Tinitario; González-Gay, Miguel Á

2016-01-01

To investigate the reliability and validity of the Spanish version of the 2010 American College of Rheumatology (ACR) Preliminary Diagnostic Criteria for Fibromyalgia (FM) in patients with chronic pain. The 2010 ACR Preliminary Diagnostic Criteria for FM were adapted to a Spanish version following the guidelines of the Rheumatology Spanish Society Study Group of FM. Based on the 1990 ACR classi cation criteria for FM, patients with chronic pain were initially divided into two groups: a FM group and another group of non-FM individuals. Patients from the FM group were evaluated by tender points (TP) examination, Fibromyalgia Impact Questionnaire (FIQ), Widespread Pain Index (WPI), and Symptom Severity Scale (SSS). The non-FM (control) group included patients with rheumatoid arthritis (RA) and osteoarthritis (OA). They were evaluated by WPI and SSS. We included 1,169 patients divided into two groups: FM group (n=803; 777 women and 26 men) and non-FM group (n= 366; 147 patients with RA, and 219 with OA). The median value of TP and FIQ in the FM group was 16 and 74 respectively. The preliminary 2010 ACR criteria were met by 665 (82.8%) FM patients and by 112 (30.6%) patients from the non-FM group (pFIQ (p<0.0001), WPI (p<0.0001) and SSS (p<0.0001) were observed when FM patients fulfilling the 2010 ACR criteria were compared with the remaining FM patients who did not fulfill these criteria. Sensitivity of the Spanish version of the 2010 ACR criteria was 85.6% (95%CI: 83.1-88.1), speci city 73.2% (95%CI: 68.4-78), positive predictive value 87.7% (95%CI: 85.3-90.1) and negative predictive value 69.4% (95%CI: 64.5-74.2). Our results indicate that the 2010 ACR Preliminary Diagnostic Criteria for FM may be useful to establish a diagnosis of FM in Spanish individuals with chronic pain.

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

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

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)

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

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.

Quantitative software-reliability analysis of computer codes relevant to nuclear safety

International Nuclear Information System (INIS)

Mueller, C.J.

1981-12-01

This report presents the results of the first year of an ongoing research program to determine the probability of failure characteristics of computer codes relevant to nuclear safety. An introduction to both qualitative and quantitative aspects of nuclear software is given. A mathematical framework is presented which will enable the a priori prediction of the probability of failure characteristics of a code given the proper specification of its properties. The framework consists of four parts: (1) a classification system for software errors and code failures; (2) probabilistic modeling for selected reliability characteristics; (3) multivariate regression analyses to establish predictive relationships among reliability characteristics and generic code property and development parameters; and (4) the associated information base. Preliminary data of the type needed to support the modeling and the predictions of this program are described. Illustrations of the use of the modeling are given but the results so obtained, as well as all results of code failure probabilities presented herein, are based on data which at this point are preliminary, incomplete, and possibly non-representative of codes relevant to nuclear safety

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

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.

Development and preliminary reliability of a multitasking assessment for executive functioning after concussion.

Science.gov (United States)

Smith, Laurel B; Radomski, Mary Vining; Davidson, Leslie Freeman; Finkelstein, Marsha; Weightman, Margaret M; McCulloch, Karen L; Scherer, Matthew R

2014-01-01

OBJECTIVES. Executive functioning deficits may result from concussion. The Charge of Quarters (CQ) Duty Task is a multitask assessment designed to assess executive functioning in servicemembers after concussion. In this article, we discuss the rationale and process used in the development of the CQ Duty Task and present pilot data from the preliminary evaluation of interrater reliability (IRR). METHOD. Three evaluators observed as 12 healthy participants performed the CQ Duty Task and measured performance using various metrics. Intraclass correlation coefficient (ICC) quantified IRR. RESULTS. The ICC for task completion was .94. ICCs for other assessment metrics were variable. CONCLUSION. Preliminary IRR data for the CQ Duty Task are encouraging, but further investigation is needed to improve IRR in some domains. Lessons learned in the development of the CQ Duty Task could benefit future test development efforts with populations other than the military. Copyright © 2014 by the American Occupational Therapy Association, Inc.

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

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…

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

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

Lifetime prediction and reliability estimation methodology for Stirling-type pulse tube refrigerators by gaseous contamination accelerated degradation testing

Science.gov (United States)

Wan, Fubin; Tan, Yuanyuan; Jiang, Zhenhua; Chen, Xun; Wu, Yinong; Zhao, Peng

2017-12-01

Lifetime and reliability are the two performance parameters of premium importance for modern space Stirling-type pulse tube refrigerators (SPTRs), which are required to operate in excess of 10 years. Demonstration of these parameters provides a significant challenge. This paper proposes a lifetime prediction and reliability estimation method that utilizes accelerated degradation testing (ADT) for SPTRs related to gaseous contamination failure. The method was experimentally validated via three groups of gaseous contamination ADT. First, the performance degradation model based on mechanism of contamination failure and material outgassing characteristics of SPTRs was established. Next, a preliminary test was performed to determine whether the mechanism of contamination failure of the SPTRs during ADT is consistent with normal life testing. Subsequently, the experimental program of ADT was designed for SPTRs. Then, three groups of gaseous contamination ADT were performed at elevated ambient temperatures of 40 °C, 50 °C, and 60 °C, respectively and the estimated lifetimes of the SPTRs under normal condition were obtained through acceleration model (Arrhenius model). The results show good fitting of the degradation model with the experimental data. Finally, we obtained the reliability estimation of SPTRs through using the Weibull distribution. The proposed novel methodology enables us to take less than one year time to estimate the reliability of the SPTRs designed for more than 10 years.

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...

Waste Feed Delivery System Phase 1 Preliminary Reliability and Availability and Maintainability Analysis [SEC 1 and 2

International Nuclear Information System (INIS)

CARLSON, A.B.

1999-01-01

The document presents updated results of the preliminary reliability, availability, maintainability analysis performed for delivery of waste feed from tanks 241-AZ-101 and 241-AN-105 to British Nuclear Fuels Limited, inc. under the Tank Waste Remediation System Privatization Contract. The operational schedule delay risk is estimated and contributing factors are discussed

Waste Feed Delivery System Phase 1 Preliminary Reliability and Availability and Maintainability Analysis [SEC 1 and 2

Energy Technology Data Exchange (ETDEWEB)

CARLSON, A.B.

1999-11-11

The document presents updated results of the preliminary reliability, availability, maintainability analysis performed for delivery of waste feed from tanks 241-AZ-101 and 241-AN-105 to British Nuclear Fuels Limited, inc. under the Tank Waste Remediation System Privatization Contract. The operational schedule delay risk is estimated and contributing factors are discussed.

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.)

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)

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

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.

Reliability analysis for Atucha II reactor protection system signals

International Nuclear Information System (INIS)

Roca, Jose Luis

1996-01-01

Atucha II is a 745 MW Argentine Power Nuclear Reactor constructed by ENACE SA, Nuclear Argentine Company for Electrical Power Generation and SIEMENS AG KWU, Erlangen, Germany. A preliminary modular logic analysis of RPS (Reactor Protection System) signals was performed by means of the well known Swedish professional risk and reliability software named Risk-Spectrum taking as a basis a reference signal coded as JR17ER003 which command the two moderator loops valves. From the reliability and behavior knowledge for this reference signal follows an estimation of the reliability for the other 97 RPS signals. Because the preliminary character of this analysis Main Important Measures are not performed at this stage. Reliability is by the statistic value named unavailability predicted. The scope of this analysis is restricted from the measurement elements to the RPS buffer outputs. In the present context only one redundancy is analyzed so in the Instrumentation and Control area there no CCF (Common Cause Failures) present for signals. Finally those unavailability values could be introduced in the failure domain for the posterior complete Atucha II reliability analysis which includes all mechanical and electromechanical features. Also an estimation of the spurious frequency of RPS signals defined as faulty by no trip is performed

Reliability analysis for Atucha II reactor protection system signals

International Nuclear Information System (INIS)

Roca, Jose L.

2000-01-01

Atucha II is a 745 MW Argentine power nuclear reactor constructed by Nuclear Argentine Company for Electric Power Generation S.A. (ENACE S.A.) and SIEMENS AG KWU, Erlangen, Germany. A preliminary modular logic analysis of RPS (Reactor Protection System) signals was performed by means of the well known Swedish professional risk and reliability software named Risk-Spectrum taking as a basis a reference signal coded as JR17ER003 which command the two moderator loops valves. From the reliability and behavior knowledge for this reference signal follows an estimation of the reliability for the other 97 RPS signals. Because the preliminary character of this analysis Main Important Measures are not performed at this stage. Reliability is by the statistic value named unavailability predicted. The scope of this analysis is restricted from the measurement elements to the RPS buffer outputs. In the present context only one redundancy is analyzed so in the Instrumentation and Control area there no CCF (Common Cause Failures) present for signals. Finally those unavailability values could be introduced in the failure domain for the posterior complete Atucha II reliability analysis which includes all mechanical and electromechanical features. Also an estimation of the spurious frequency of RPS signals defined as faulty by no trip is performed. (author)

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.

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.

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).

The Japanese version of the modified ACR preliminary diagnostic criteria for fibromyalgia and the fibromyalgia symptom scale: reliability and validity.

Science.gov (United States)

Usui, Chie; Hatta, Kotaro; Aratani, Satoko; Yagishita, Naoko; Nishioka, Kenya; Kanazawa, Teruhisa; Itoh, Kenji; Yamano, Yoshihisa; Nakamura, Hiroyuki; Nakajima, Toshihiro; Nishioka, Kusuki

2013-09-01

The aim of this study is to investigate the reliability and validity of the Japanese version of the modified American College of Rheumatology (ACR) Preliminary Diagnostic Criteria for Fibromyalgia (mACR 2010-J) and the Fibromyalgia Symptom Scale (mFS-J). According to the ACR 1990 classification criteria, patients with chronic pain were divided into the fibromyalgia group and nonfibromyalgia group (rheumatoid arthritis and osteoarthritis). Patients in both groups were assessed using mACR 2010-J and mFS-J. 294 of 462 (64 %) patients in the fibromyalgia group met mACR 2010-J, whereas 4 % (9/231) of the nonfibromyalgia group did, with sensitivity of 64 %, specificity of 96 %, positive predictive value of 97 %, negative predictive value of 56 %, and positive likelihood ratio of 16.3. Mean total scores on mFS-J significantly differentiated the fibromyalgia from the nonfibromyalgia group. According to the value of the Youden index, the best cutoff score for the mFS-J was 9/10. Our findings indicate that mACR 2010-J as a positive test and mFS-J as a quantification scale might be suitable for assessing fibromyalgia among Japanese chronic pain populations.

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

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.

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…

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

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...

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

Preliminary checkout on the reliability and validity of nuclear and radiation effect psychological effect rating scale (NRERS)

International Nuclear Information System (INIS)

Yin Zhongwei; Xie Huaijiang; Yang Chengjun; Yin Xuhui

2009-01-01

Objective: To preliminarily evaluate the reliability and validity of the NRPES. Methods: NRPES, SDS and SAS were applied to assess the psychological sate of 352 soldiers, 80 soldiers were randomly selected to determine with NRPES again, which at last contribute to assess the reliability and validity of NRPES. Results: The satisfactory reliability and Cronbach a coefficient respectively were 0.756 and 0.698. The sixth and eighth factor of the principal component analysis are combined together to a new factor, the results indicate the constructive validity is adaptive to the primary design of the questionnaire. NRPES and its 7 factors have a greater significant relation and the correlation coefficient which is from 0.569 ∼ 0.878. There is a great significant correlation between the NRPES, factor x1, x2, x3 and SDS, SAS, the correlation coefficient of which are over 0.5. Conclusion: Though NRPES has some shortcomings,which need to be improved late, NRPES has a better reliability and validity through the preliminary checkout. (authors)

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.

Contaminants in landfill soils - Reliability of prefeasibility studies.

Science.gov (United States)

Hölzle, Ingo

2017-05-01

Recent landfill mining studies have researched the potential for resource recovery using samples from core drilling or grab cranes. However, most studies used small sample numbers, which may not represent the heterogeneous landfill composition. As a consequence, there exists a high risk of an incorrect economic and/or ecological evaluation. The main objective of this work is to investigate the possibilities and limitations of preliminary investigations concerning the crucial soil composition. The preliminary samples of landfill investigations were compared to the excavation samples from three completely excavated landfills in Germany. In addition, the research compared the reliability of prediction of the two investigation methods, core drilling and grab crane. Sampling using a grab crane led to better results, even for smaller investigations of 10 samples. Analyses of both methods showed sufficiently accurate results to make predictions (standard error 5%, level of confidence 95%) for most heavy metals, cyanide and PAH in the dry substance and for sulphate, barium, Benzo[a]pyrene, pH and the electrical conductivity in leachate analyses of soil type waste. While chrome and nickel showed less accurate results, the concentrations of hydrocarbons, TOC, DOC, PCB and fluorine (leachate) were not predictable even for sample numbers of up to 59. Overestimations of pollutant concentrations were more frequently apparent in drilling, and underestimations when using a grab crane. The dispersion of the element and elemental composition had no direct impact on the reliability of prediction. Thus, an individual consideration of the particular element or elemental composition for dry substance and leachate analyses is recommended to adapt the sample strategy and calculate an optimum sample number. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

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

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

Preliminary study of soil permeability properties using principal component analysis

Science.gov (United States)

Yulianti, M.; Sudriani, Y.; Rustini, H. A.

2018-02-01

Soil permeability measurement is undoubtedly important in carrying out soil-water research such as rainfall-runoff modelling, irrigation water distribution systems, etc. It is also known that acquiring reliable soil permeability data is rather laborious, time-consuming, and costly. Therefore, it is desirable to develop the prediction model. Several studies of empirical equations for predicting permeability have been undertaken by many researchers. These studies derived the models from areas which soil characteristics are different from Indonesian soil, which suggest a possibility that these permeability models are site-specific. The purpose of this study is to identify which soil parameters correspond strongly to soil permeability and propose a preliminary model for permeability prediction. Principal component analysis (PCA) was applied to 16 parameters analysed from 37 sites consist of 91 samples obtained from Batanghari Watershed. Findings indicated five variables that have strong correlation with soil permeability, and we recommend a preliminary permeability model, which is potential for further development.

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.

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

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.

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.

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

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

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.

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.

Reliability of early radiographic evaluations for canine hip dysplasia obtained from the standard ventrodorsal radiographic projection

International Nuclear Information System (INIS)

Corley, E.A.; Keller, G.G.; Lattimer, J.C.; Ellersieck, M.R.

1997-01-01

To determine reliability of preliminary evaluations for canine hip dysplasia (CHD) performed by the Orthopedic Foundation for Animals on dogs between 3 and 18 months of age. Retrospective analysis of data from the Orthopedic Foundation for Animals database. 2,332 Golden Retrievers, Labrador Retrievers, German Shepherd Dogs, and Rottweilers for which preliminary evaluation had been performed between 3 and 18 months of age and for which results of a definitive evaluation performed after 24 months of age were available. Each radiograph was evaluated, and hip joint status was graded as excellent, good, fair, or borderline phenotype or mild, moderate, or severe dysplasia. Preliminary evaluations were performed by 1 radiologist; definitive evaluations were the consensus of 3 radiologists. Reliability of preliminary evaluations was calculated as the percentage of definitive evaluations (normal vs dysplastic) that were unchanged from preliminary evaluations. Reliability of a preliminary evaluation of normal hip joint phenotype decreased significantly as the preliminary evaluation changed from excellent (100%) to good (97.9%) to fair (76.9%) phenotype. Reliability of a preliminary evaluation of CHD increased significantly as the preliminary evaluation changed from mild (84.4%) to moderate (97.4%) CHD. Reliability of preliminary evaluations increased significantly as age at the time of preliminary evaluation increased, regardless of whether dogs received a preliminary evaluation of normal phenotype or CHD. Results suggest that preliminary evaluations of hip joint status in dogs are generally reliable. However, dogs that receive a preliminary evaluation of fair phenotype of mild CHD should be reevaluated after 24 months of age

The PedsQL™ Present Functioning Visual Analogue Scales: preliminary reliability and validity

Directory of Open Access Journals (Sweden)

Varni James W

2006-10-01

Full Text Available Abstract Background The PedsQL™ Present Functioning Visual Analogue Scales (PedsQL™ VAS were designed as an ecological momentary assessment (EMA instrument to rapidly measure present or at-the-moment functioning in children and adolescents. The PedsQL™ VAS assess child self-report and parent-proxy report of anxiety, sadness, anger, worry, fatigue, and pain utilizing six developmentally appropriate visual analogue scales based on the well-established Varni/Thompson Pediatric Pain Questionnaire (PPQ Pain Intensity VAS format. Methods The six-item PedsQL™ VAS was administered to 70 pediatric patients ages 5–17 and their parents upon admittance to the hospital environment (Time 1: T1 and again two hours later (Time 2: T2. It was hypothesized that the PedsQL™ VAS Emotional Distress Summary Score (anxiety, sadness, anger, worry and the fatigue VAS would demonstrate moderate to large effect size correlations with the PPQ Pain Intensity VAS, and that patient" parent concordance would increase over time. Results Test-retest reliability was demonstrated from T1 to T2 in the large effect size range. Internal consistency reliability was demonstrated for the PedsQL™ VAS Total Symptom Score (patient self-report: T1 alpha = .72, T2 alpha = .80; parent proxy-report: T1 alpha = .80, T2 alpha = .84 and Emotional Distress Summary Score (patient self-report: T1 alpha = .74, T2 alpha = .73; parent proxy-report: T1 alpha = .76, T2 alpha = .81. As hypothesized, the Emotional Distress Summary Score and Fatigue VAS were significantly correlated with the PPQ Pain VAS in the medium to large effect size range, and patient and parent concordance increased from T1 to T2. Conclusion The results demonstrate preliminary test-retest and internal consistency reliability and construct validity of the PedsQL™ Present Functioning VAS instrument for both pediatric patient self-report and parent proxy-report. Further field testing is required to extend these initial

A preliminary model to identify low-risk MBA applicants

Directory of Open Access Journals (Sweden)

CA Bisschoff

2014-08-01

The reliability of the discriminant function rates favourably with 71% (MBA in 3 years, 62% (MBA in 4 years and 83% (dropping out of the programme being categorised correctly by the respective discriminant functions. Being a preliminary model, its predictive capabilities need to be verified in practice before it can  be implemented as tool to render assistance in MBA admissions.  The value of this research lies  in the fact that it constitutes a model that could be employed and improved as a predictive tool in an environment where very limited predictive tools exist.  Therefore, although it is by no means a tried and tested model, it sets the scene by supplying a scientific base from which incremental improvements could result.

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.

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.

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.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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)

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....

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)

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

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

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

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....

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...

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

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

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.

Reliability and validity of the Wolfram Unified Rating Scale (WURS

Directory of Open Access Journals (Sweden)

Nguyen Chau

2012-11-01

Full Text Available Abstract Background Wolfram syndrome (WFS is a rare, neurodegenerative disease that typically presents with childhood onset insulin dependent diabetes mellitus, followed by optic atrophy, diabetes insipidus, deafness, and neurological and psychiatric dysfunction. There is no cure for the disease, but recent advances in research have improved understanding of the disease course. Measuring disease severity and progression with reliable and validated tools is a prerequisite for clinical trials of any new intervention for neurodegenerative conditions. To this end, we developed the Wolfram Unified Rating Scale (WURS to measure the severity and individual variability of WFS symptoms. The aim of this study is to develop and test the reliability and validity of the Wolfram Unified Rating Scale (WURS. Methods A rating scale of disease severity in WFS was developed by modifying a standardized assessment for another neurodegenerative condition (Batten disease. WFS experts scored the representativeness of WURS items for the disease. The WURS was administered to 13 individuals with WFS (6-25 years of age. Motor, balance, mood and quality of life were also evaluated with standard instruments. Inter-rater reliability, internal consistency reliability, concurrent, predictive and content validity of the WURS were calculated. Results The WURS had high inter-rater reliability (ICCs>.93, moderate to high internal consistency reliability (Cronbach’s α = 0.78-0.91 and demonstrated good concurrent and predictive validity. There were significant correlations between the WURS Physical Assessment and motor and balance tests (rs>.67, ps>.76, ps=-.86, p=.001. The WURS demonstrated acceptable content validity (Scale-Content Validity Index=0.83. Conclusions These preliminary findings demonstrate that the WURS has acceptable reliability and validity and captures individual differences in disease severity in children and young adults with WFS.

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)

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.

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...

Preliminary prediction of inflow into the D-holes at the Stripa Mine

International Nuclear Information System (INIS)

Long, J.C.S.; Karasaki, K.; Davey, A.; Peterson, J.; Landsfeld, M.; Kemeny, J.; Martel, S.

1990-02-01

Lawrence Berkeley Laboratory (LBL) is contracted by the US Department of Energy to provide an auxiliary modeling effort for the Stripa Project. Within this effort, we are making calculations of inflow to the Simulated Drift Experiment (SDE), i.e. inflow to six parallel, closely spaced D-holes, using a preliminary set of data collected in five other holes, the N- and W-holes during Stages 1 and 2 of the Site Characterization and Validation (SCV) project. Our approach has been to focus on the fracture zones rather than the general set of ubiquitous fractures. Approximately 90% of all the water flowing in the rock is flowing in fracture zones which are neither uniformly conductive nor are they infinitely extensive. Our approach has been to adopt the fracture zone locations as they have been identified with geophysics. We use geologic sense and the original geophysical data to add one zone where significant water inflow has been observed that can not be explained with the other geophysical zones. This report covers LBL's preliminary prediction of flow into the D-holes. Care should be taken in interpreting the results given in this report. As explained below, the approach that LBL has designed for developing a fracture hydrology model requires cross-hole hydrologic data. Cross-hole tests are planned for Stage 3 but were unavailable in Stage 1. As such, we have inferred from available data what a cross-hole test might show and used this synthetic data to make a preliminary calculation of the inflow into the D-holes. Then using all the Stage 3 data we will calculate flow into the Validation Drift itself. The report mainly demonstrates the use of our methodology and the simulated results should be considered preliminary

Preliminary lifetime predictions for 304 stainless steel as the LANL ABC blanket material

International Nuclear Information System (INIS)

Park, J.J.; Buksa, J.J.; Houts, M.G.; Arthur, E.D.

1997-11-01

The prediction of materials lifetime in the preconceptual Los Alamos National Laboratory (LANL) Accelerator-Based Conversion of Plutonium (ABC) is of utmost interest. Because Hastelloy N showed good corrosion resistance to the Oak Ridge National Laboratory Molten Salt Reactor Experiment fuel salt that is similar to the LANL ABC fuel salt, Hastelloy N was originally proposed for the LANL ABC blanket material. In this paper, the possibility of using 304 stainless steel as a replacement for the Hastelloy N is investigated in terms of corrosion issues and fluence-limit considerations. An attempt is made, based on the previous Fast Flux Test Facility design data, to predict the preliminary lifetime estimate of the 304 stainless steel used in the blanket region of the LANL ABC

The Cambridge Otology Quality of Life Questionnaire: an otology-specific patient-recorded outcome measure. A paper describing the instrument design and a report of preliminary reliability and validity.

Science.gov (United States)

Martin, T P C; Moualed, D; Paul, A; Ronan, N; Tysome, J R; Donnelly, N P; Cook, R; Axon, P R

2015-04-01

The Cambridge Otology Quality of Life Questionnaire (COQOL) is a patient-recorded outcome measurement (PROM) designed to quantify the quality of life of patients attending otology clinics. Item-reduction model. A systematically designed long-form version (74 items) was tested with patient focus groups before being presented to adult otology patients (n. 137). Preliminary item analysis tested reliability, reducing the COQOL to 24 questions. This was then presented in conjunction with the SF-36 (V1) questionnaire to a total of 203 patients. Subsequently, these were re-presented at T + 3 months, and patients recorded whether they felt their condition had improved, deteriorated or remained the same. Non-responders were contacted by post. A correlation between COQOL scores and patient perception of change was examined to analyse content validity. Teaching hospital and university psychology department. Adult patients attending otology clinics with a wide range of otological conditions. Item reliability measured by item–total correlation, internal consistency and test– retest reliability. Validity measured by correlation between COQOL scores and patient-reported symptom change. Reliability: the COQOL showed excellent internal consistency at both initial presentation (a = 0.90) and 3 months later (a = 0.93). Validity: One-way analysis of variance showed a significant difference between groups reporting change and those reporting no change in quality of life (F(2, 80) = 5.866, P < 0.01). The COQOL is the first otology-specific PROM. Initial studies demonstrate excellent reliability and encouraging preliminary criterion validity: further studies will allow a deeper validation of the instrument.

[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.

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.

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)

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.

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

A Tutorial on Nonlinear Time-Series Data Mining in Engineering Asset Health and Reliability Prediction: Concepts, Models, and Algorithms

Directory of Open Access Journals (Sweden)

Ming Dong

2010-01-01

Full Text Available The primary objective of engineering asset management is to optimize assets service delivery potential and to minimize the related risks and costs over their entire life through the development and application of asset health and usage management in which the health and reliability prediction plays an important role. In real-life situations where an engineering asset operates under dynamic operational and environmental conditions, the lifetime of an engineering asset is generally described as monitored nonlinear time-series data and subject to high levels of uncertainty and unpredictability. It has been proved that application of data mining techniques is very useful for extracting relevant features which can be used as parameters for assets diagnosis and prognosis. In this paper, a tutorial on nonlinear time-series data mining in engineering asset health and reliability prediction is given. Besides that an overview on health and reliability prediction techniques for engineering assets is covered, this tutorial will focus on concepts, models, algorithms, and applications of hidden Markov models (HMMs and hidden semi-Markov models (HSMMs in engineering asset health prognosis, which are representatives of recent engineering asset health prediction techniques.

Preliminary Analysis of LORAN-C System Reliability for Civil Aviation.

Science.gov (United States)

1981-09-01

overviev of the analysis technique. Section 3 describes the computerized LORAN-C coverage model which is used extensively in the reliability analysis...Xth Plenary Assembly, Geneva, 1963, published by International Telecomunications Union. S. Braff, R., Computer program to calculate a Karkov Chain Reliability Model, unpublished york, MITRE Corporation. A-1 I.° , 44J Ili *Y 0E 00 ...F i8 1110 Prelim inary Analysis of Program Engineering & LORAN’C System ReliabilityMaintenance Service i ~Washington. D.C.

An Introduction To Reliability

International Nuclear Information System (INIS)

Park, Kyoung Su

1993-08-01

This book introduces reliability with definition of reliability, requirement of reliability, system of life cycle and reliability, reliability and failure rate such as summary, reliability characteristic, chance failure, failure rate which changes over time, failure mode, replacement, reliability in engineering design, reliability test over assumption of failure rate, and drawing of reliability data, prediction of system reliability, conservation of system, failure such as summary and failure relay and analysis of system safety.

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...

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.

Cell emulation and preliminary results.

Science.gov (United States)

2016-07-01

This report details preliminary results of the testing plan implemented by the Hawaii Natural Energy Institute to evaluate Electric Vehicle (EV) battery durability and reliability under electric utility grid operations. Commercial EV battery cells ar...

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.

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.

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.

Life prediction and mechanical reliability of NT551 silicon nitride

Science.gov (United States)

Andrews, Mark Jay

551. For the same reasons, the predicted and actual fatigue performance did not correlate well. The results of this study should not be considered a limitation of the life prediction algorithm but emphasize the requirement that ceramics be homogeneous and strength-limiting flaws uniformly distributed as a perquisite for accurate life prediction and reliability analyses.

Reliability Analysis Techniques for Communication Networks in Nuclear Power Plant

International Nuclear Information System (INIS)

Lim, T. J.; Jang, S. C.; Kang, H. G.; Kim, M. C.; Eom, H. S.; Lee, H. J.

2006-09-01

The objectives of this project is to investigate and study existing reliability analysis techniques for communication networks in order to develop reliability analysis models for nuclear power plant's safety-critical networks. It is necessary to make a comprehensive survey of current methodologies for communication network reliability. Major outputs of this study are design characteristics of safety-critical communication networks, efficient algorithms for quantifying reliability of communication networks, and preliminary models for assessing reliability of safety-critical communication networks

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....

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

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...

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.

[Social Avoidance and Distress Scale (SAD) and Fear of Negative Evaluation Scale (FNE)--reliability and the preliminary assessment of validity].

Science.gov (United States)

Sobański, Jerzy A; Klasa, Katarzyna; Rutkowski, Krzysztof; Dembińska, Edyta; Müldner-Nieckowski, Łukasz; Cyranka, Katarzyna

2013-01-01

Assessment of reliability, cross-validity and usefulness in everyday clinical practice of two related tools: Social Avoidance and Distress Scale (SAD) and Fear of Negative Evaluation Scale (FNE). Analysis of tests results of 453 females and 172 males diagnosed in the years 2008-2010 in the Outpatient Clinic for Neurotic and Behavioral Disorders of the Cracow University Hospital, including, inter alia, results of the questionnaires SAD and FNE. The scales have been, with the consent of their authors (R. Friend) and the copyright holder (APA), translated into Polish and back-translated. Subjects also completed the symptom checklist KO '0'(n = 512), and neurotic personality questionnaire KON-2006 (n = 505), as well as the NEO-PI-R personality inventory (n = 46). The reliability and cross-validity coefficients of Polish versions were assessed in the patient population and their results were compared with those of the group of 75 medical students. The translation was verified by retranslation. The reliability coefficients of Polish version of the SAD and FNE scales turned out to be high--Cronbach's alpha coefficient was 0.94 for both scales, Guttman's split-half reliability coefficient 0.93. Correlations with symptom checklist KO '0 'and neurotic personality questionnaire KON-2006, as well as with the NEO -PI-R personality inventory were significant and indicate a good cross-validity of the analyzed tools. The average results in the patient population for both scales were significantly higher than the results in the preliminary control group of medical students. Polish versions of SAD and FNE questionnaires, like their other translations from English, proved to be reliable and have a high cross-validity with other original Polish tools used in the diagnosis of neurotic disorders, which allows to recommend them to be used in further studies, also in comparing healthy persons with those suffering from a variety of neurotic disorders.

Reasoning with Inductive Argument Test: A Study of Validity and Reliability

Directory of Open Access Journals (Sweden)

Mehmet Emrah Karadere

2013-12-01

Conclusion: The preliminary data obtained from the study of reliability and validity of the scale shows that ‘Reasoning with Inductive Argument Test’ supports reliability and validity in Turkish population. [JCBPR 2013; 2(3.000: 156-161

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...

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.

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.

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.)

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

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.

Software reliability studies

Science.gov (United States)

Hoppa, Mary Ann; Wilson, Larry W.

1994-01-01

There are many software reliability models which try to predict future performance of software based on data generated by the debugging process. Our research has shown that by improving the quality of the data one can greatly improve the predictions. We are working on methodologies which control some of the randomness inherent in the standard data generation processes in order to improve the accuracy of predictions. Our contribution is twofold in that we describe an experimental methodology using a data structure called the debugging graph and apply this methodology to assess the robustness of existing models. The debugging graph is used to analyze the effects of various fault recovery orders on the predictive accuracy of several well-known software reliability algorithms. We found that, along a particular debugging path in the graph, the predictive performance of different models can vary greatly. Similarly, just because a model 'fits' a given path's data well does not guarantee that the model would perform well on a different path. Further we observed bug interactions and noted their potential effects on the predictive process. We saw that not only do different faults fail at different rates, but that those rates can be affected by the particular debugging stage at which the rates are evaluated. Based on our experiment, we conjecture that the accuracy of a reliability prediction is affected by the fault recovery order as well as by fault interaction.

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

A study of operational and testing reliability in software reliability analysis

International Nuclear Information System (INIS)

Yang, B.; Xie, M.

2000-01-01

Software reliability is an important aspect of any complex equipment today. Software reliability is usually estimated based on reliability models such as nonhomogeneous Poisson process (NHPP) models. Software systems are improving in testing phase, while it normally does not change in operational phase. Depending on whether the reliability is to be predicted for testing phase or operation phase, different measure should be used. In this paper, two different reliability concepts, namely, the operational reliability and the testing reliability, are clarified and studied in detail. These concepts have been mixed up or even misused in some existing literature. Using different reliability concept will lead to different reliability values obtained and it will further lead to different reliability-based decisions made. The difference of the estimated reliabilities is studied and the effect on the optimal release time is investigated

Preliminary review of critical shutdown heat removal items for common cause failure susceptibility on LMFBR's. [LMFBR

Energy Technology Data Exchange (ETDEWEB)

Allard, L.T.; Elerath, J.G.

1976-02-01

This document presents a common cause failure analysis for Critical LMFBR Shutdown Heat Removal Systems. The report is intended to outline a systematic approach to defining areas with significant potential for common causes of failure, and ultimately provide inputs to the reliability prediction model. A preliminary evaluation of postulatd single initiating causes resulting in multiple failures of LMFBR-SHRS items is presented in Appendix C. This document will be periodically updated to reflect new information and activity.

Pocket Handbook on Reliability

Science.gov (United States)

1975-09-01

exponencial distributions Weibull distribution, -xtimating reliability, confidence intervals, relia- bility growth, 0. P- curves, Bayesian analysis. 20 A S...introduction for those not familiar with reliability and a good refresher for those who are currently working in the area. LEWIS NERI, CHIEF...includes one or both of the following objectives: a) prediction of the current system reliability, b) projection on the system reliability for someI future

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,

Reliability of Power Electronic Converter Systems

DEFF Research Database (Denmark)

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

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.

LED system reliability

NARCIS (Netherlands)

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

2011-01-01

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

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.

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.

Reliability of nine programs of topological predictions and their application to integral membrane channel and carrier proteins.

Science.gov (United States)

Reddy, Abhinay; Cho, Jaehoon; Ling, Sam; Reddy, Vamsee; Shlykov, Maksim; Saier, Milton H

2014-01-01

We evaluated topological predictions for nine different programs, HMMTOP, TMHMM, SVMTOP, DAS, SOSUI, TOPCONS, PHOBIUS, MEMSAT-SVM (hereinafter referred to as MEMSAT), and SPOCTOPUS. These programs were first evaluated using four large topologically well-defined families of secondary transporters, and the three best programs were further evaluated using topologically more diverse families of channels and carriers. In the initial studies, the order of accuracy was: SPOCTOPUS > MEMSAT > HMMTOP > TOPCONS > PHOBIUS > TMHMM > SVMTOP > DAS > SOSUI. Some families, such as the Sugar Porter Family (2.A.1.1) of the Major Facilitator Superfamily (MFS; TC #2.A.1) and the Amino Acid/Polyamine/Organocation (APC) Family (TC #2.A.3), were correctly predicted with high accuracy while others, such as the Mitochondrial Carrier (MC) (TC #2.A.29) and the K(+) transporter (Trk) families (TC #2.A.38), were predicted with much lower accuracy. For small, topologically homogeneous families, SPOCTOPUS and MEMSAT were generally most reliable, while with large, more diverse superfamilies, HMMTOP often proved to have the greatest prediction accuracy. We next developed a novel program, TM-STATS, that tabulates HMMTOP, SPOCTOPUS or MEMSAT-based topological predictions for any subdivision (class, subclass, superfamily, family, subfamily, or any combination of these) of the Transporter Classification Database (TCDB; www.tcdb.org) and examined the following subclasses: α-type channel proteins (TC subclasses 1.A and 1.E), secreted pore-forming toxins (TC subclass 1.C) and secondary carriers (subclass 2.A). Histograms were generated for each of these subclasses, and the results were analyzed according to subclass, family and protein. The results provide an update of topological predictions for integral membrane transport proteins as well as guides for the development of more reliable topological prediction programs, taking family-specific characteristics into account. © 2014 S. Karger AG, Basel.

Field reliability of electronic systems

International Nuclear Information System (INIS)

Elm, T.

1984-02-01

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

Investigation of low glass transition temperature on COTS PEMs reliability

Science.gov (United States)

Sandor, M.; Agarwal, S.

2002-01-01

Many factors influence PEM component reliability.One of the factors that can affect PEM performance and reliability is the glass transition temperature (Tg) and the coefficient of thermal expansion (CTE) of the encapsulant or underfill. JPL/NASA is investigating how the Tg and CTE for PEMs affect device reliability under different temperature and aging conditions. Other issues with Tg are also being investigated. Some preliminary data will be presented on glass transition temperature test results conducted at JPL.

Preliminary Reliability and Validity of an Exercise Benefits and Barriers for Stroke Prevention Scale in an African American Sample.

Science.gov (United States)

Aycock, Dawn M; Clark, Patricia C

2015-01-01

African Americans are at heightened risk of first stroke, and regular exercise can reduce stroke risk. Benefits and barriers to exercise subscales from 2 instruments were combined to create the Exercise Benefits and Barriers for Stroke Prevention (EBBSP) scale. Reliability and validity of the EBBSP scale were examined in a nonrandom sample of 66 African Americans who were primarily female, average age 43.3 ± 9.4 years, and high school graduates. Both subscales had adequate internal consistency reliability. Factor analysis revealed two factors for each subscale. More benefits and fewer perceived barriers were significantly related to current exercise and future intentions to exercise. The EBBSP scale may be useful in research focused on understanding, predicting, and promoting exercise for stroke prevention in adults.

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

Calculating system reliability with SRFYDO

Energy Technology Data Exchange (ETDEWEB)

Morzinski, Jerome [Los Alamos National Laboratory; Anderson - Cook, Christine M [Los Alamos National Laboratory; Klamann, Richard M [Los Alamos National Laboratory

2010-01-01

SRFYDO is a process for estimating reliability of complex systems. Using information from all applicable sources, including full-system (flight) data, component test data, and expert (engineering) judgment, SRFYDO produces reliability estimates and predictions. It is appropriate for series systems with possibly several versions of the system which share some common components. It models reliability as a function of age and up to 2 other lifecycle (usage) covariates. Initial output from its Exploratory Data Analysis mode consists of plots and numerical summaries so that the user can check data entry and model assumptions, and help determine a final form for the system model. The System Reliability mode runs a complete reliability calculation using Bayesian methodology. This mode produces results that estimate reliability at the component, sub-system, and system level. The results include estimates of uncertainty, and can predict reliability at some not-too-distant time in the future. This paper presents an overview of the underlying statistical model for the analysis, discusses model assumptions, and demonstrates usage of SRFYDO.

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.

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.

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

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.

Reliability analysis techniques for the design engineer

International Nuclear Information System (INIS)

Corran, E.R.; Witt, H.H.

1982-01-01

This paper describes a fault tree analysis package that eliminates most of the housekeeping tasks involved in proceeding from the initial construction of a fault tree to the final stage of presenting a reliability analysis in a safety report. It is suitable for designers with relatively little training in reliability analysis and computer operation. Users can rapidly investigate the reliability implications of various options at the design stage and evolve a system which meets specified reliability objectives. Later independent review is thus unlikely to reveal major shortcomings necessitating modification and project delays. The package operates interactively, allowing the user to concentrate on the creative task of developing the system fault tree, which may be modified and displayed graphically. For preliminary analysis, system data can be derived automatically from a generic data bank. As the analysis proceeds, improved estimates of critical failure rates and test and maintenance schedules can be inserted. The technique is applied to the reliability analysis of the recently upgraded HIFAR Containment Isolation System. (author)

PV Systems Reliability Final Technical Report.

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-01

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

Reliability of the Client-Centeredness of Goal Setting (C-COGS) Scale in Acquired Brain Injury Rehabilitation.

Science.gov (United States)

Doig, Emmah; Prescott, Sarah; Fleming, Jennifer; Cornwell, Petrea; Kuipers, Pim

2016-01-01

To examine the internal reliability and test-retest reliability of the Client-Centeredness of Goal Setting (C-COGS) scale. The C-COGS scale was administered to 42 participants with acquired brain injury after completion of multidisciplinary goal planning. Internal reliability of scale items was examined using item-partial total correlations and Cronbach's α coefficient. The scale was readministered within a 1-mo period to a subsample of 12 participants to examine test-retest reliability by calculating exact and close percentage agreement for each item. After examination of item-partial total correlations, test items were revised. The revised items demonstrated stronger internal consistency than the original items. Preliminary evaluation of test-retest reliability was fair, with an average exact percent agreement across all test items of 67%. Findings support the preliminary reliability of the C-COGS scale as a tool to evaluate and promote client-centered goal planning in brain injury rehabilitation. Copyright © 2016 by the American Occupational Therapy Association, Inc.

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

Evolving Reliability and Maintainability Allocations for NASA Ground Systems

Science.gov (United States)

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

2016-01-01

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

PRmePRed: A protein arginine methylation prediction tool.

Directory of Open Access Journals (Sweden)

Pawan Kumar

Full Text Available Protein methylation is an important Post-Translational Modification (PTMs of proteins. Arginine methylation carries out and regulates several important biological functions, including gene regulation and signal transduction. Experimental identification of arginine methylation site is a daunting task as it is costly as well as time and labour intensive. Hence reliable prediction tools play an important task in rapid screening and identification of possible methylation sites in proteomes. Our preliminary assessment using the available prediction methods on collected data yielded unimpressive results. This motivated us to perform a comprehensive data analysis and appraisal of features relevant in the context of biological significance, that led to the development of a prediction tool PRmePRed with better performance. The PRmePRed perform reasonably well with an accuracy of 84.10%, 82.38% sensitivity, 83.77% specificity, and Matthew's correlation coefficient of 66.20% in 10-fold cross-validation. PRmePRed is freely available at http://bioinfo.icgeb.res.in/PRmePRed/.

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

Preliminary Computational Analysis of the (HIRENASD) Configuration in Preparation for the Aeroelastic Prediction Workshop

Science.gov (United States)

Chwalowski, Pawel; Florance, Jennifer P.; Heeg, Jennifer; Wieseman, Carol D.; Perry, Boyd P.

2011-01-01

This paper presents preliminary computational aeroelastic analysis results generated in preparation for the first Aeroelastic Prediction Workshop (AePW). These results were produced using FUN3D software developed at NASA Langley and are compared against the experimental data generated during the HIgh REynolds Number Aero- Structural Dynamics (HIRENASD) Project. The HIRENASD wind-tunnel model was tested in the European Transonic Windtunnel in 2006 by Aachen University0s Department of Mechanics with funding from the German Research Foundation. The computational effort discussed here was performed (1) to obtain a preliminary assessment of the ability of the FUN3D code to accurately compute physical quantities experimentally measured on the HIRENASD model and (2) to translate the lessons learned from the FUN3D analysis of HIRENASD into a set of initial guidelines for the first AePW, which includes test cases for the HIRENASD model and its experimental data set. This paper compares the computational and experimental results obtained at Mach 0.8 for a Reynolds number of 7 million based on chord, corresponding to the HIRENASD test conditions No. 132 and No. 159. Aerodynamic loads and static aeroelastic displacements are compared at two levels of the grid resolution. Harmonic perturbation numerical results are compared with the experimental data using the magnitude and phase relationship between pressure coefficients and displacement. A dynamic aeroelastic numerical calculation is presented at one wind-tunnel condition in the form of the time history of the generalized displacements. Additional FUN3D validation results are also presented for the AGARD 445.6 wing data set. This wing was tested in the Transonic Dynamics Tunnel and is commonly used in the preliminary benchmarking of computational aeroelastic software.

Human reliability in complex systems: an overview

International Nuclear Information System (INIS)

Embrey, D.E.

1976-07-01

A detailed analysis is presented of the main conceptual background underlying the areas of human reliability and human error. The concept of error is examined and generalized to that of human reliability, and some of the practical and methodological difficulties of reconciling the different standpoints of the human factors specialist and the engineer discussed. Following a survey of general reviews available on human reliability, quantitative techniques for prediction of human reliability are considered. An in-depth critical analysis of the various quantitative methods is then presented, together with the data bank requirements for human reliability prediction. Reliability considerations in process control and nuclear plant, and also areas of design, maintenance, testing and emergency situations are discussed. The effects of stress on human reliability are analysed and methods of minimizing these effects discussed. Finally, a summary is presented and proposals for further research are set out. (author)

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.

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.

A preliminary examination of the validity and reliability of a new brief rating scale for symptom domains of psychosis: Brief Evaluation of Psychosis Symptom Domains (BE-PSD).

Science.gov (United States)

Takeuchi, Hiroyoshi; Fervaha, Gagan; Lee, Jimmy; Agid, Ofer; Remington, Gary

2016-09-01

Brief assessments have the potential to be widely adopted as outcome measures in research but also routine clinical practice. Existing brief rating scales that assess symptoms of schizophrenia or psychosis have a number of limitations including inability to capture five symptom domains of psychosis and a lack of clearly defined operational anchor points for scoring. We developed a new brief rating scale for five symptom domains of psychosis with clearly defined operational anchor points - the Brief Evaluation of Psychosis Symptom Domains (BE-PSD). To examine the psychometric properties of the BE-PSD, fifty patients with schizophrenia or schizoaffective disorder were included in this preliminary cross-sectional study. To test the convergent and discriminant validity of the BE-PSD, correlational analyses were employed using the consensus Positive and Negative Syndrome Scale (PANSS) five-factor model. To examine the inter-rater reliability of the BE-PSD, single measures intraclass correlation coefficients (ICCs) were calculated for 11 patients. The BE-PSD domain scores demonstrated high convergent validity with the corresponding PANSS factor score (rs = 0.81-0.93) as well as good discriminant validity, as evidenced by lower correlations with the other PANSS factors (rs = 0.23-0.62). The BE-PSD also demonstrated excellent inter-rater reliability for each of the domain scores and the total scores (ICC(2,1) = 0.79-0.96). The present preliminary study found the BE-PSD measure to be valid and reliable; however, further studies are needed to establish the psychometric properties of the BE-PSD because of the limitations such as the small sample size and lacking data on test-retest reliability or sensitivity to change. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reliability and validity of the parent efficacy for child healthy weight behaviour (PECHWB) scale.

Science.gov (United States)

Palmer, F; Davis, M C

2014-05-01

Interventions for childhood overweight and obesity that target parents as the agents of change by increasing parent self-efficacy for facilitating their child's healthy weight behaviours require a reliable and valid tool to measure parent self-efficacy before and after interventions. Nelson and Davis developed the Parent Efficacy for Child Healthy Weight Behaviour (PECHWB) scale with good preliminary evidence of reliability and validity. The aim of this research was to provide further psychometric evidence from an independent Australian sample. Data were provided by a convenience sample of 261 primary caregivers of children aged 4-17 years via an online survey. PECHWB scores were correlated with scores on other self-report measures of parenting efficacy and 2- to 4-week test-retest reliability of the PECHWB was assessed. The results of the study confirmed the four-factor structure of the PECHWB (Fat and Sugar, Sedentary Behaviours, Physical Activity, and Fruit and Vegetables) and provided strong evidence of internal consistency and test-retest reliability, as well as good evidence of convergent validity. Future research should investigate the properties of the PECHWB in a sample of parents of overweight or obese children, including measures of child weight and actual child healthy weight behaviours to provide evidence of the concurrent and predictive validity of PECHWB scores. © 2013 John Wiley & Sons Ltd.

Reliability factors of tube-to-tubesheet joints

International Nuclear Information System (INIS)

Sang, Z.F.; Zhu, Y.Z.; Widera, G.E.O.

1992-01-01

The main purpose of this paper is to provide an applicable method to establish reliability factors for expanded tube-to-tubesheet joints. The paper also reports on the results of a preliminary study to validate experimentally the reliability efficiencies listed in Table A-2 of Appendix A of Section VIII, Division 1, of the ASME Boiler and Pressure Vessel Code. A comparison between the actual reliability factors f r , determined from testing the damage strength of the joint and calculated according to Appendix A-4 of the ASME Code, and those of Table A-2 is carried out. The results are discussed in light of the restrictions inherent in Table A-2. It is confirmed that some existing values of f r are conservative while others are less so. (orig.)

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.)

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.

Wind turbine reliability : a database and analysis approach.

Energy Technology Data Exchange (ETDEWEB)

Linsday, James (ARES Corporation); Briand, Daniel; Hill, Roger Ray; Stinebaugh, Jennifer A.; Benjamin, Allan S. (ARES Corporation)

2008-02-01

The US wind Industry has experienced remarkable growth since the turn of the century. At the same time, the physical size and electrical generation capabilities of wind turbines has also experienced remarkable growth. As the market continues to expand, and as wind generation continues to gain a significant share of the generation portfolio, the reliability of wind turbine technology becomes increasingly important. This report addresses how operations and maintenance costs are related to unreliability - that is the failures experienced by systems and components. Reliability tools are demonstrated, data needed to understand and catalog failure events is described, and practical wind turbine reliability models are illustrated, including preliminary results. This report also presents a continuing process of how to proceed with controlling industry requirements, needs, and expectations related to Reliability, Availability, Maintainability, and Safety. A simply stated goal of this process is to better understand and to improve the operable reliability of wind turbine installations.

Preliminary testing of the reliability and feasibility of SAGE: a system to measure and score engagement with and use of research in health policies and programs.

Science.gov (United States)

Makkar, Steve R; Williamson, Anna; D'Este, Catherine; Redman, Sally

2017-12-19

Few measures of research use in health policymaking are available, and the reliability of such measures has yet to be evaluated. A new measure called the Staff Assessment of Engagement with Evidence (SAGE) incorporates an interview that explores policymakers' research use within discrete policy documents and a scoring tool that quantifies the extent of policymakers' research use based on the interview transcript and analysis of the policy document itself. We aimed to conduct a preliminary investigation of the usability, sensitivity, and reliability of the scoring tool in measuring research use by policymakers. Nine experts in health policy research and two independent coders were recruited. Each expert used the scoring tool to rate a random selection of 20 interview transcripts, and each independent coder rated 60 transcripts. The distribution of scores among experts was examined, and then, interrater reliability was tested within and between the experts and independent coders. Average- and single-measure reliability coefficients were computed for each SAGE subscales. Experts' scores ranged from the limited to extensive scoring bracket for all subscales. Experts as a group also exhibited at least a fair level of interrater agreement across all subscales. Single-measure reliability was at least fair except for three subscales: Relevance Appraisal, Conceptual Use, and Instrumental Use. Average- and single-measure reliability among independent coders was good to excellent for all subscales. Finally, reliability between experts and independent coders was fair to excellent for all subscales. Among experts, the scoring tool was comprehensible, usable, and sensitive to discriminate between documents with varying degrees of research use. Secondly, the scoring tool yielded scores with good reliability among the independent coders. There was greater variability among experts, although as a group, the tool was fairly reliable. The alignment between experts' and independent

Reliability of construction materials

International Nuclear Information System (INIS)

Merz, H.

1976-01-01

One can also speak of reliability with respect to materials. While for reliability of components the MTBF (mean time between failures) is regarded as the main criterium, this is replaced with regard to materials by possible failure mechanisms like physical/chemical reaction mechanisms, disturbances of physical or chemical equilibrium, or other interactions or changes of system. The main tasks of the reliability analysis of materials therefore is the prediction of the various failure reasons, the identification of interactions, and the development of nondestructive testing methods. (RW) [de

Bayesian methods in reliability

Science.gov (United States)

Sander, P.; Badoux, R.

1991-11-01

The present proceedings from a course on Bayesian methods in reliability encompasses Bayesian statistical methods and their computational implementation, models for analyzing censored data from nonrepairable systems, the traits of repairable systems and growth models, the use of expert judgment, and a review of the problem of forecasting software reliability. Specific issues addressed include the use of Bayesian methods to estimate the leak rate of a gas pipeline, approximate analyses under great prior uncertainty, reliability estimation techniques, and a nonhomogeneous Poisson process. Also addressed are the calibration sets and seed variables of expert judgment systems for risk assessment, experimental illustrations of the use of expert judgment for reliability testing, and analyses of the predictive quality of software-reliability growth models such as the Weibull order statistics.

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

Structural Reliability Methods

DEFF Research Database (Denmark)

Ditlevsen, Ove Dalager; Madsen, H. O.

The structural reliability methods quantitatively treat the uncertainty of predicting the behaviour and properties of a structure given the uncertain properties of its geometry, materials, and the actions it is supposed to withstand. This book addresses the probabilistic methods for evaluation...... of structural reliability, including the theoretical basis for these methods. Partial safety factor codes under current practice are briefly introduced and discussed. A probabilistic code format for obtaining a formal reliability evaluation system that catches the most essential features of the nature...... of the uncertainties and their interplay is the developed, step-by-step. The concepts presented are illustrated by numerous examples throughout the text....

On Bayesian System Reliability Analysis

Energy Technology Data Exchange (ETDEWEB)

Soerensen Ringi, M

1995-05-01

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

On Bayesian System Reliability Analysis

International Nuclear Information System (INIS)

Soerensen Ringi, M.

1995-01-01

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

The 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.

Wind Speed Prediction with Wavelet Time Series Based on Lorenz Disturbance

Directory of Open Access Journals (Sweden)

ZHANG, Y.

2017-08-01

Full Text Available Due to the sustainable and pollution-free characteristics, wind energy has been one of the fastest growing renewable energy sources. However, the intermittent and random fluctuation of wind speed presents many challenges for reliable wind power integration and normal operation of wind farm. Accurate wind speed prediction is the key to ensure the safe operation of power system and to develop wind energy resources. Therefore, this paper has presented a wavelet time series wind speed prediction model based on Lorenz disturbance. Therefore, in this paper, combined with the atmospheric dynamical system, a wavelet-time series improved wind speed prediction model based on Lorenz disturbance is proposed and the wind turbines of different climate types in Spain and China are used to simulate the disturbances of Lorenz equations with different initial values. The prediction results show that the improved model can effectively correct the preliminary prediction of wind speed, improving the prediction. In a word, the research work in this paper will be helpful to arrange the electric power dispatching plan and ensure the normal operation of the wind farm.

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)

An Early Years Toolbox for Assessing Early Executive Function, Language, Self-Regulation, and Social Development: Validity, Reliability, and Preliminary Norms.

Science.gov (United States)

Howard, Steven J; Melhuish, Edward

2017-06-01

Several methods of assessing executive function (EF), self-regulation, language development, and social development in young children have been developed over previous decades. Yet new technologies make available methods of assessment not previously considered. In resolving conceptual and pragmatic limitations of existing tools, the Early Years Toolbox (EYT) offers substantial advantages for early assessment of language, EF, self-regulation, and social development. In the current study, results of our large-scale administration of this toolbox to 1,764 preschool and early primary school students indicated very good reliability, convergent validity with existing measures, and developmental sensitivity. Results were also suggestive of better capture of children's emerging abilities relative to comparison measures. Preliminary norms are presented, showing a clear developmental trajectory across half-year age groups. The accessibility of the EYT, as well as its advantages over existing measures, offers considerably enhanced opportunities for objective measurement of young children's abilities to enable research and educational applications.

Reliability criteria selection for integrated resource planning

International Nuclear Information System (INIS)

Ruiu, D.; Ye, C.; Billinton, R.; Lakhanpal, D.

1993-01-01

A study was conducted on the selection of a generating system reliability criterion that ensures a reasonable continuity of supply while minimizing the total costs to utility customers. The study was conducted using the Institute for Electronic and Electrical Engineers (IEEE) reliability test system as the study system. The study inputs and results for conditions and load forecast data, new supply resources data, demand-side management resource data, resource planning criterion, criterion value selection, supply side development, integrated resource development, and best criterion values, are tabulated and discussed. Preliminary conclusions are drawn as follows. In the case of integrated resource planning, the selection of the best value for a given type of reliability criterion can be done using methods similar to those used for supply side planning. The reliability criteria values previously used for supply side planning may not be economically justified when integrated resource planning is used. Utilities may have to revise and adopt new, and perhaps lower supply reliability criteria for integrated resource planning. More complex reliability criteria, such as energy related indices, which take into account the magnitude, frequency and duration of the expected interruptions are better adapted than the simpler capacity-based reliability criteria such as loss of load expectation. 7 refs., 5 figs., 10 tabs

Use of reliability engineering in development and manufacturing of metal parts

International Nuclear Information System (INIS)

Khan, A.; Iqbal, M.A.; Asif, M.

2005-01-01

The reliability engineering predicts modes of failures and weak links before the system is built instead of failure case study. The reliability engineering analysis will help in the manufacturing economy, assembly accuracy and qualification by testing, leading to production of metal parts in an aerospace industry. This methodology will also minimize the performance constraints in any requirement for the application of metal components in aerospace systems. The reliability engineering predicts the life of the parts under loading conditions whether dynamic or static. Reliability predictions can help engineers in making decisions about design of components, materials selection and qualification under applied stress levels. Two methods of reliability prediction i.e. Part Stress Analysis and Part Count have been used in this study. In this paper we will discuss how these two methods can be used to measure reliability of a system during development phases, which includes the measuring effect of environmental and operational variables. The equations are used to measure the reliability of each type of component, as well as, integration for measuring system applied for the reliability analysis. (author)

Reliable and accurate point-based prediction of cumulative infiltration using soil readily available characteristics: A comparison between GMDH, ANN, and MLR

Science.gov (United States)

Rahmati, Mehdi

2017-08-01

Developing accurate and reliable pedo-transfer functions (PTFs) to predict soil non-readily available characteristics is one of the most concerned topic in soil science and selecting more appropriate predictors is a crucial factor in PTFs' development. Group method of data handling (GMDH), which finds an approximate relationship between a set of input and output variables, not only provide an explicit procedure to select the most essential PTF input variables, but also results in more accurate and reliable estimates than other mostly applied methodologies. Therefore, the current research was aimed to apply GMDH in comparison with multivariate linear regression (MLR) and artificial neural network (ANN) to develop several PTFs to predict soil cumulative infiltration point-basely at specific time intervals (0.5-45 min) using soil readily available characteristics (RACs). In this regard, soil infiltration curves as well as several soil RACs including soil primary particles (clay (CC), silt (Si), and sand (Sa)), saturated hydraulic conductivity (Ks), bulk (Db) and particle (Dp) densities, organic carbon (OC), wet-aggregate stability (WAS), electrical conductivity (EC), and soil antecedent (θi) and field saturated (θfs) water contents were measured at 134 different points in Lighvan watershed, northwest of Iran. Then, applying GMDH, MLR, and ANN methodologies, several PTFs have been developed to predict cumulative infiltrations using two sets of selected soil RACs including and excluding Ks. According to the test data, results showed that developed PTFs by GMDH and MLR procedures using all soil RACs including Ks resulted in more accurate (with E values of 0.673-0.963) and reliable (with CV values lower than 11 percent) predictions of cumulative infiltrations at different specific time steps. In contrast, ANN procedure had lower accuracy (with E values of 0.356-0.890) and reliability (with CV values up to 50 percent) compared to GMDH and MLR. The results also revealed

The Adolescent HIV Disclosure Cognition and Affect Scale: Preliminary Reliability and Validity.

Science.gov (United States)

Evangeli, Michael

2017-07-01

Globally, there are 2 million HIV-positive 10-19-year-olds. One challenge for this population is sharing their HIV status with others (onward HIV disclosure). There are no multi-item, multidimensional scales of HIV disclosure cognitions and affect for young people living with HIV. An 18-item measure of HIV disclosure cognition and affect was developed, administered to 65 adolescents living with HIV (aged 12-16 years). Data were explored using principal component analysis and preliminary construct and criterion validity assessed. Three factors were revealed: negative disclosure attitudes and feelings, self-efficacy, and positive disclosure attitudes and feelings. The full scale and its subscales were internally consistent. The total score showed statistically significant positive relationships with HIV disclosure in the past 6 months, HIV disclosure intention and self-perception. Preliminary evidence of the measure's good psychometric properties suggests it may be helpful in future clinical and research work. © The Author 2017. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Digital Processor Module Reliability Analysis of Nuclear Power Plant

International Nuclear Information System (INIS)

Lee, Sang Yong; Jung, Jae Hyun; Kim, Jae Ho; Kim, Sung Hun

2005-01-01

The system used in plant, military equipment, satellite, etc. consists of many electronic parts as control module, which requires relatively high reliability than other commercial electronic products. Specially, Nuclear power plant related to the radiation safety requires high safety and reliability, so most parts apply to Military-Standard level. Reliability prediction method provides the rational basis of system designs and also provides the safety significance of system operations. Thus various reliability prediction tools have been developed in recent decades, among of them, the MI-HDBK-217 method has been widely used as a powerful tool for the prediction. In this work, It is explained that reliability analysis work for Digital Processor Module (DPM, control module of SMART) is performed by Parts Stress Method based on MIL-HDBK-217F NOTICE2. We are using the Relex 7.6 of Relex software corporation, because reliability analysis process requires enormous part libraries and data for failure rate calculation

Pelvic Incidence: A Predictive Factor for Three-Dimensional Acetabular Orientation—A Preliminary Study

Directory of Open Access Journals (Sweden)

Christophe Boulay

2014-01-01

Full Text Available Acetabular cup orientation (inclination and anteversion is a fundamental topic in orthopaedics and depends on pelvis tilt (positional parameter emphasising the notion of a safe range of pelvis tilt. The hypothesis was that pelvic incidence (morphologic parameter could yield a more accurate and reliable assessment than pelvis tilt. The aim was to find out a predictive equation of acetabular 3D orientation parameters which were determined by pelvic incidence to include in the model. The second aim was to consider the asymmetry between the right and left acetabulae. Twelve pelvic anatomic specimens were measured with an electromagnetic Fastrak system (Polhemus Society providing 3D position of anatomical landmarks to allow measurement of acetabular and pelvic parameters. Acetabulum and pelvis data were correlated by a Spearman matrix. A robust linear regression analysis provided prediction of acetabulum axes. The orientation of each acetabulum could be predicted by the incidence. The incidence is correlated with the morphology of acetabula. The asymmetry of the acetabular roof was correlated with pelvic incidence. This study allowed analysis of relationships of acetabular orientation and pelvic incidence. Pelvic incidence (morphologic parameter could determine the safe range of pelvis tilt (positional parameter for an individual and not a group.

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.

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

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

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

Preliminary Human Reliability Issues in Reviewing SMART PSA

International Nuclear Information System (INIS)

Lee, Chang Ju; Sheen, Cheol

2010-01-01

Human reliability analysis (HRA) identifies the human failure events (HFEs) that can negatively impact normal or emergency plant operations, and systematically estimates probabilities of HFEs using data (when available), models, or expert judgment. In case of newly-conceptualized reactors like SMART (System-integrated Modular Advanced Reactor), HRA results must be provided by first evaluating the applicability of a set of human errors that has been typically applied in PSAs for existing PWRs. Additional human errors should also be identified reflecting its unique design and operational features. The objective of this paper is double-folded: to discuss a direction of HRA used in confirming risk level of SAMRT-type reactors; and to extract preliminarily considerable points or issues for regulatory verification, referred to available safety guides

Preliminary results of steel containment vessel model test

International Nuclear Information System (INIS)

Matsumoto, T.; Komine, K.; Arai, S.

1997-01-01

A high pressure test of a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of a steel containment vessel (SCV), representing an improved boiling water reactor (BWR) Mark II containment, was conducted on December 11-12, 1996 at Sandia National Laboratories. This paper describes the preliminary results of the high pressure test. In addition, the preliminary post-test measurement data and the preliminary comparison of test data with pretest analysis predictions are also presented

Culture Representation in Human Reliability Analysis

Energy Technology Data Exchange (ETDEWEB)

David Gertman; Julie Marble; Steven Novack

2006-12-01

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

Modeling high-Power Accelerators Reliability-SNS LINAC (SNS-ORNL); MAX LINAC (MYRRHA)

International Nuclear Information System (INIS)

Pitigoi, A. E.; Fernandez Ramos, P.

2013-01-01

Improving reliability has recently become a very important objective in the field of particle accelerators. The particle accelerators in operation are constantly undergoing modifications, and improvements are implemented using new technologies, more reliable components or redundant schemes (to obtain more reliability, strength, more power, etc.) A reliability model of SNS (Spallation Neutron Source) LINAC has been developed within MAX project and analysis of the accelerator systems reliability has been performed within the MAX project, using the Risk Spectrum reliability analysis software. The analysis results have been evaluated by comparison with the SNS operational data. Results and conclusions are presented in this paper, oriented to identify design weaknesses and provide recommendations for improving reliability of MYRRHA linear accelerator. The SNS reliability model developed for the MAX preliminary design phase indicates possible avenues for further investigation that could be needed to improve the reliability of the high-power accelerators, in view of the future reliability targets of ADS accelerators.

Reliability Analysis on NPP's Safety-Related Control Module with Field Data

International Nuclear Information System (INIS)

Lee, Sang Yong; Jung, Jae Hyun; Kim, Seong Hun

2006-01-01

The automatic control systems used in nuclear power plant (NPP) consists of numerous control modules that can be considered to be a network of components various complex ways. The control modules require relatively high reliability than industrial electronic products. Reliability prediction provides the rational basis of system designs and also provides the safety significance of system operations. The aim of this paper is to minimize the deficiencies of the traditional reliability prediction method calculation using the available field return data. This way is possible to do more realistic reliability assessment. SAMCHANG Enterprise Company (SEC) has established database containing high quality data at the module and component level from module maintenance in NPP. On the basis of these, this paper compares results that add failure record (field data) to Telcordia-SR-332 reliability prediction model with MIL-HDBK-217F prediction results

Rock mass evaluation for predicting tunnel constructability in the preliminary investigation stage. Phenomena causing difficult tunneling and rockburst prediction

International Nuclear Information System (INIS)

Shin, Koichi; Sawada, Masataka; Inohara, Yoshiki; Shidahara, Takumi; Hatano, Teruyoshi

2011-01-01

For the selection of the Detailed Investigation Areas for HLW disposal, predicting the tunnel constructability is one of the requirements together with assessing long-term safety. This report is the 1st of the three papers dealing with the evaluation of tunnel constructability. This paper deals with the geological factors relating to difficult tunneling such as squeezing, rockburst, and others. Also it deals with the prediction of rockburst. The 2nd paper will deal with the prediction of squeezing. The 3rd paper deals with the engineering characteristics of rock mass through rock mass classification. This paper about difficult tunneling has been based upon analysis of more than 500 tunneling reports about 280 tunnel constructions. The causes of difficult tunneling are related to (1) underground water, (2) mechanical properties of the rock, or (3) others such as gas. The geological factors for excessive water inflow are porous volcanic product of Quarternary, fault crush zone and hydrothermally altered zone of Green Tuff area, and degenerated mixed rock in accretionary complex. The geological factors for squeezing are solfataric clay at Quarternary volcanic zone, fault crush zone and hydrothermally altered zone of Green Tuff area, mudstone and fault crush zone of sedimentary rock of Neogene and later. Information useful for predicting rockburst has been gathered from previous reports. In the preliminary investigation stage, geological survey, geophysical survey and borehole survey from the surface are the source of information. Therefore rock type, P-wave velocity from seismic exploration and in-situ rock stress from hydrofracturing have been considered. Majority of rockburst events occurred at granitic rock, excluding coal mine where different kind of rockburst occurred at pillars. And P-wave velocity was around 5 km/s at the rock of rockburst events. Horizontal maximum and minimum stresses SH and Sh have been tested as a criterion for rockburst. It has been

Predictive assays of tumor radiocurability: towards a custom-made radiotherapy

International Nuclear Information System (INIS)

Cosset, J.M; Girinsky, T.; Guichard, M.; Eschwege, F.; Malaise, E.P.; Peters, L.J.; Mornex, F.

1990-01-01

Up to now, radiation oncologists had at their disposal only a number of well-known histological and clinical factors in order to define the optimal dose which should be delivered to a given tumor. Recently, radiobiological studies have suggested additional parameters which may play a major role in tumor radiocurability. These parameters are: the number of clonogenic cells, intrinsic radiosensitivity, hypoxia and proliferation kinetics. Predictive tests are being developed and evaluated for each of these parameters. The more advanced studies deal with intrinsic radiosensitivity; preliminary data show impressive variations in radiosensitivity within groups of clinically homogeneous tumors. Should these tests prove to be reliably predictive of radiocurability, it will be possible in the near future to propose to any given patient a custom-made radiotherapy adapted to the precise features of his or her tumor [fr

Adapting the helpful responses questionnaire to assess communication skills involved in delivering contingency management: preliminary psychometrics.

Science.gov (United States)

Hartzler, Bryan

2015-08-01

A paper/pencil instrument, adapted from Miller and colleagues' (1991) Helpful Responses Questionnaire (HRQ), was developed to assess clinician skill with core communicative aspects involved in delivering contingency management (CM). The instrument presents a single vignette consisting of six points of client dialogue to which respondents write 'what they would say next.' In the context of an implementation/effectiveness hybrid trial, 19 staff clinicians at an opiate treatment program completed serial training outcome assessments before, following, and three months after CM training. Assessments included this adaptation of the HRQ, a multiple-choice CM knowledge test, and a recorded standardized patient encounter scored for CM skillfulness. Study results reveal promising psychometric properties for the instrument, including strong scoring reliability, internal consistency, concurrent and predictive validity, test-retest reliability and sensitivity to training effects. These preliminary findings suggest the instrument is a viable, practical method to assess clinician skill in communicative aspects of CM delivery. Copyright © 2015 Elsevier Inc. All rights reserved.

Reliability of Degree-Day Models to Predict the Development Time of Plutella xylostella (L.) under Field Conditions.

Science.gov (United States)

Marchioro, C A; Krechemer, F S; de Moraes, C P; Foerster, L A

2015-12-01

The diamondback moth, Plutella xylostella (L.), is a cosmopolitan pest of brassicaceous crops occurring in regions with highly distinct climate conditions. Several studies have investigated the relationship between temperature and P. xylostella development rate, providing degree-day models for populations from different geographical regions. However, there are no data available to date to demonstrate the suitability of such models to make reliable projections on the development time for this species in field conditions. In the present study, 19 models available in the literature were tested regarding their ability to accurately predict the development time of two cohorts of P. xylostella under field conditions. Only 11 out of the 19 models tested accurately predicted the development time for the first cohort of P. xylostella, but only seven for the second cohort. Five models correctly predicted the development time for both cohorts evaluated. Our data demonstrate that the accuracy of the models available for P. xylostella varies widely and therefore should be used with caution for pest management purposes.

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)

Approach to developing reliable space reactor power systems

International Nuclear Information System (INIS)

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

1991-01-01

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

Preliminary investigation on reliability of genomic estimated breeding values in the Danish and Swedish Holstein Population

DEFF Research Database (Denmark)

Su, G; Guldbrandtsen, B; Gregersen, V R

2010-01-01

or no effects, and a single prior distribution common for all SNP. It was found that, in general, the model with a common prior distribution of scaling factors had better predictive ability than any mixture prior models. Therefore, a common prior model was used to estimate SNP effects and breeding values......Abstract This study investigated the reliability of genomic estimated breeding values (GEBV) in the Danish Holstein population. The data in the analysis included 3,330 bulls with both published conventional EBV and single nucleotide polymorphism (SNP) markers. After data editing, 38,134 SNP markers...... were available. In the analysis, all SNP were fitted simultaneously as random effects in a Bayesian variable selection model, which allows heterogeneous variances for different SNP markers. The response variables were the official EBV. Direct GEBV were calculated as the sum of individual SNP effects...

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

Directory of Open Access Journals (Sweden)

Agata McCormac

2017-11-01

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

External Validation and Evaluation of Reliability and Validity of the Modified Seoul National University Renal Stone Complexity Scoring System to Predict Stone-Free Status After Retrograde Intrarenal Surgery.

Science.gov (United States)

Park, Juhyun; Kang, Minyong; Jeong, Chang Wook; Oh, Sohee; Lee, Jeong Woo; Lee, Seung Bae; Son, Hwancheol; Jeong, Hyeon; Cho, Sung Yong

2015-08-01

The modified Seoul National University Renal Stone Complexity scoring system (S-ReSC-R) for retrograde intrarenal surgery (RIRS) was developed as a tool to predict stone-free rate (SFR) after RIRS. We externally validated the S-ReSC-R. We retrospectively reviewed 159 patients who underwent RIRS. The S-ReSC-R was assigned from 1 to 12 according to the location and number of sites involved. The stone-free status was defined as no evidence of a stone or with clinically insignificant residual fragment stones less than 2 mm. Interobserver and test-retest reliabilities were evaluated. Statistical performance of the prediction model was assessed by its predictive accuracy, predictive probability, and clinical usefulness. Overall SFR was 73.0%. The SFRs were 86.7%, 70.2%, and 48.6% in low-score (1-2), intermediate-score (3-4), and high-score (5-12) groups, respectively (pR revealed an area under the curve (AUC) of 0.731 (95% CI 0.650-0.813). The AUC of the three-titered S-ReSC-R was 0.701 (95% CI 0.609-0.794). The calibration plot showed that the predicted probability of SFR had a concordance comparable to that of observed frequency. The Hosmer-Lemeshow goodness of fit test revealed a p-value of 0.01 for the S-ReSC-R and 0.90 for the three-titered S-ReSC-R. Interobserver and test-retest reliabilities revealed an almost perfect level of agreement. The present study proved the predictive value of S-ReSC-R to predict SFR following RIRS in an independent cohort. Interobserver and test-retest reliabilities confirmed that S-ReSC-R was reliable and valid.

Predicting visual semantic descriptive terms from radiological image data: preliminary results with liver lesions in CT.

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Depeursinge, Adrien; Kurtz, Camille; Beaulieu, Christopher; Napel, Sandy; Rubin, Daniel

2014-08-01

We describe a framework to model visual semantics of liver lesions in CT images in order to predict the visual semantic terms (VST) reported by radiologists in describing these lesions. Computational models of VST are learned from image data using linear combinations of high-order steerable Riesz wavelets and support vector machines (SVM). In a first step, these models are used to predict the presence of each semantic term that describes liver lesions. In a second step, the distances between all VST models are calculated to establish a nonhierarchical computationally-derived ontology of VST containing inter-term synonymy and complementarity. A preliminary evaluation of the proposed framework was carried out using 74 liver lesions annotated with a set of 18 VSTs from the RadLex ontology. A leave-one-patient-out cross-validation resulted in an average area under the ROC curve of 0.853 for predicting the presence of each VST. The proposed framework is expected to foster human-computer synergies for the interpretation of radiological images while using rotation-covariant computational models of VSTs to 1) quantify their local likelihood and 2) explicitly link them with pixel-based image content in the context of a given imaging domain.

Prediction of the Main Engine Power of a New Container Ship at the Preliminary Design Stage

Science.gov (United States)

Cepowski, Tomasz

2017-06-01

The paper presents mathematical relationships that allow us to forecast the estimated main engine power of new container ships, based on data concerning vessels built in 2005-2015. The presented approximations allow us to estimate the engine power based on the length between perpendiculars and the number of containers the ship will carry. The approximations were developed using simple linear regression and multivariate linear regression analysis. The presented relations have practical application for estimation of container ship engine power needed in preliminary parametric design of the ship. It follows from the above that the use of multiple linear regression to predict the main engine power of a container ship brings more accurate solutions than simple linear regression.

Preliminary tests of the electrostatic plasma accelerator

Science.gov (United States)

Aston, G.; Acker, T.

1990-01-01

This report describes the results of a program to verify an electrostatic plasma acceleration concept and to identify those parameters most important in optimizing an Electrostatic Plasma Accelerator (EPA) thruster based upon this thrust mechanism. Preliminary performance measurements of thrust, specific impulse and efficiency were obtained using a unique plasma exhaust momentum probe. Reliable EPA thruster operation was achieved using one power supply.

Reliability studies of diagnostic methods in Indian traditional Ayurveda medicine: An overview

Science.gov (United States)

Kurande, Vrinda Hitendra; Waagepetersen, Rasmus; Toft, Egon; Prasad, Ramjee

2013-01-01

Recently, a need to develop supportive new scientific evidence for contemporary Ayurveda has emerged. One of the research objectives is an assessment of the reliability of diagnoses and treatment. Reliability is a quantitative measure of consistency. It is a crucial issue in classification (such as prakriti classification), method development (pulse diagnosis), quality assurance for diagnosis and treatment and in the conduct of clinical studies. Several reliability studies are conducted in western medicine. The investigation of the reliability of traditional Chinese, Japanese and Sasang medicine diagnoses is in the formative stage. However, reliability studies in Ayurveda are in the preliminary stage. In this paper, examples are provided to illustrate relevant concepts of reliability studies of diagnostic methods and their implication in practice, education, and training. An introduction to reliability estimates and different study designs and statistical analysis is given for future studies in Ayurveda. PMID:23930037

Antisocial personality disorder and psychopathy in women: a literature review on the reliability and validity of assessment instruments.

Science.gov (United States)

Dolan, Mairead; Völlm, Birgit

2009-01-01

Crime rates are low in women compared to men. The two disorders most commonly associated with offending behaviour, antisocial personality disorder (ASPD) and psychopathy, are also less prevalent in female samples. However, developments in forensic psychiatry have often ignored gender, and the utility of constructs such as psychopathy and their assessment instruments in female samples remains unclear. This article presents a review of studies looking at rates of ASPD and psychopathy and on the reliability and validity of assessment instruments of these disorders in women. Gender differences in symptom patterns will be considered. The literature seems to suggest that DSM-IV criteria for ASPD may lead to an underestimation of the prevalence of the disorder in women due to the requirement of childhood conduct disorder symptoms. The Psychopathy Checklist-Revised (PCL-R) is a valid and reliable instrument to identify psychopathy in women but there are gender differences in the factor structure and item loadings on this measure. Research to date seems to suggest a three-factor model may be most strongly supported in females. Preliminary evidence suggests the PCL-R may have some value in predicting future offending while the PCL:SV may be useful in predicting institutional violence. Clinical implications are discussed.

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...

Early experiences building a software quality prediction model

Science.gov (United States)

Agresti, W. W.; Evanco, W. M.; Smith, M. C.

1990-01-01

Early experiences building a software quality prediction model are discussed. The overall research objective is to establish a capability to project a software system's quality from an analysis of its design. The technical approach is to build multivariate models for estimating reliability and maintainability. Data from 21 Ada subsystems were analyzed to test hypotheses about various design structures leading to failure-prone or unmaintainable systems. Current design variables highlight the interconnectivity and visibility of compilation units. Other model variables provide for the effects of reusability and software changes. Reported results are preliminary because additional project data is being obtained and new hypotheses are being developed and tested. Current multivariate regression models are encouraging, explaining 60 to 80 percent of the variation in error density of the subsystems.

Tracking reliability for space cabin-borne equipment in development by Crow model.

Science.gov (United States)

Chen, J D; Jiao, S J; Sun, H L

2001-12-01

Objective. To study and track the reliability growth of manned spaceflight cabin-borne equipment in the course of its development. Method. A new technique of reliability growth estimation and prediction, which is composed of the Crow model and test data conversion (TDC) method was used. Result. The estimation and prediction value of the reliability growth conformed to its expectations. Conclusion. The method could dynamically estimate and predict the reliability of the equipment by making full use of various test information in the course of its development. It offered not only a possibility of tracking the equipment reliability growth, but also the reference for quality control in manned spaceflight cabin-borne equipment design and development process.

General inattentiveness is a long-term reliable trait independently predictive of psychological health: Danish validation studies of the Mindful Attention Awareness Scale.

Science.gov (United States)

Jensen, Christian Gaden; Niclasen, Janni; Vangkilde, Signe Allerup; Petersen, Anders; Hasselbalch, Steen Gregers

2016-05-01

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 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 and mental health, after controlling for age, gender, income, socioeconomic occupational class, stressful life events, and social desirability (β = 0.32-.42, ps health. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Reliability of infrared thermometric measurements of skin temperature in the hand.

Science.gov (United States)

Packham, Tara L; Fok, Diana; Frederiksen, Karen; Thabane, Lehana; Buckley, Norman

2012-01-01

Clinical measurement study. Skin temperature asymmetries (STAs) are used in the diagnosis of complex regional pain syndrome (CRPS), but little evidence exists for reliability of the equipment and methods. This study examined the reliability of an inexpensive infrared (IR) thermometer and measurement points in the hand for the study of STA. ST was measured three times at five points on both hands with an IR thermometer by two raters in 20 volunteers (12 normals and 8 CRPS). ST measurement results using IR thermometers support inter-rater reliability: intraclass correlation coefficient (ICC) estimate for single measures 0.80; all ST measurement points were also highly reliable (ICC single measures, 0.83-0.91). The equipment demonstrated excellent reliability, with little difference in the reliability of the five measurement sites. These preliminary findings support their use in future CRPS research. Not applicable. Copyright © 2012 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Some areas of reliability technique which have been neglected to some extent - maintainability - human reliability - mechanical reliability - repairable systems

International Nuclear Information System (INIS)

Akersten, P.A.

1985-01-01

The present thesis consists of four papers, three of which are of a expositary nature and one more theoretical. The first two papers have a natural coupling to the man-machine interface. The first paper is devoted to the concept of maintainability and the role of man as maintenance technician. The second paper discusses aspects of human reliability, mainly studying man as operator. However, maintenance tasks can be studied in the same manner. The third paper concerns reliability prediction for mechanical components. This is an area of vital importance for the reliability practitioner, who needs realistic and easy-to-use mathematical models for different failure modes. The fourth paper discusses mathematical models for repairable systems, especially the problem of testing whether a constant event intensity model is adequate or not. (author)

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

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.

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.

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

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

Science.gov (United States)

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

2017-09-01

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

Reliability planning in distributed electric energy systems

Energy Technology Data Exchange (ETDEWEB)

Kahn, E.

1978-10-01

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

Reliability and mass analysis of dynamic power conversion systems with parallel or standby redundancy

Science.gov (United States)

Juhasz, Albert J.; Bloomfield, Harvey S.

1987-01-01

A combinatorial reliability approach was used to identify potential dynamic power conversion systems for space mission applications. A reliability and mass analysis was also performed, specifically for a 100-kWe nuclear Brayton power conversion system with parallel redundancy. Although this study was done for a reactor outlet temperature of 1100 K, preliminary system mass estimates are also included for reactor outlet temperatures ranging up to 1500 K.

Reliability and mass analysis of dynamic power conversion systems with parallel of standby redundancy

Science.gov (United States)

Juhasz, A. J.; Bloomfield, H. S.

1985-01-01

A combinatorial reliability approach is used to identify potential dynamic power conversion systems for space mission applications. A reliability and mass analysis is also performed, specifically for a 100 kWe nuclear Brayton power conversion system with parallel redundancy. Although this study is done for a reactor outlet temperature of 1100K, preliminary system mass estimates are also included for reactor outlet temperatures ranging up to 1500 K.

Validity and reliability of the effort-reward imbalance questionnaire in a sample of 673 Italian teachers.

Science.gov (United States)

Zurlo, Maria Clelia; Pes, Daniela; Siegrist, Johannes

2010-08-01

This study explores the explicative potential of effort-reward imbalance Model to unveil the dimensions involved in teacher stress process and analyses the psychometric characteristics of the Italian version of the ERI Questionnaire (Siegrist, J Occup Health Psychol 1:27-43, 1996) with respect to a homogeneous occupational group: Italian school teachers. The Italian version of the ERI Questionnaire was submitted to 673 teachers randomly drawn from a cross-section of school types. Internal consistency, reliability, discriminative validity, and factorial structure were evaluated. Predictive validity was explored with respect to a measure of perceived strain, the Crown-Crisp Experiential Index. Discriminative validity was explored with respect to age, gender, education, type of school, the presence/absence of physical pains in the last 12 months before the survey, and teachers' intention to leave the profession. Item-total correlations are for all items included between 0.30 and 0.80 (p teachers, which reported to suffer for physical pains. Higher efforts (T = -5.26, p teachers inclined to give up the job. Multiple regression analyses have highlighted that higher efforts, higher overcommitment, and lower rewards are significantly predictive of higher levels of free-floating and somatic anxiety as well as depression and global psychological strain. This preliminary analysis of the reliability and validity of the Italian version of the ERI Questionnaire reveals that it constitutes a useful and reliable measure to analyse work-related stress with respect to the school setting. The validity of the ERI model to describe the dimensions involved in teacher's stress and to highlight those associated to leaving intentions and to several physical and psychological strain outcomes in Italian school teachers has been confirmed.

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.

Reliability analysis and initial requirements for FC systems and stacks

Science.gov (United States)

Åström, K.; Fontell, E.; Virtanen, S.

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

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)

Predicting Tropical Cyclogenesis with a Global Mesoscale Model: Preliminary Results with Very Severe Cyclonic Storm Nargis (2008)

Science.gov (United States)

Shen, B.; Tao, W.; Atlas, R.

2008-12-01

Very Severe Cyclonic Storm Nargis, the deadliest named tropical cyclone (TC) in the North Indian Ocean Basin, devastated Burma (Myanmar) in May 2008, causing tremendous damage and numerous fatalities. An increased lead time in the prediction of TC Nargis would have increased the warning time and may therefore have saved lives and reduced economic damage. Recent advances in high-resolution global models and supercomputers have shown the potential for improving TC track and intensity forecasts, presumably by improving multi-scale simulations. The key but challenging questions to be answered include: (1) if and how realistic, in terms of timing, location and TC general structure, the global mesoscale model (GMM) can simulate TC genesis and (2) under what conditions can the model extend the lead time of TC genesis forecasts. In this study, we focus on genesis prediction for TCs in the Indian Ocean with the GMM. Preliminary real-data simulations show that the initial formation and intensity variations of TC Nargis can be realistically predicted at a lead time of up to 5 days. These simulations also suggest that the accurate representations of a westerly wind burst (WWB) and an equatorial trough, associated with monsoon circulations and/or a Madden-Julian Oscillation (MJO), are important for predicting the formation of this kind of TC. In addition to the WWB and equatorial trough, other favorable environmental conditions will be examined, which include enhanced monsoonal circulation, upper-level outflow, low- and middle-level moistening, and surface fluxes.

New horizons in mouse immunoinformatics: reliable in silico prediction of mouse class I histocompatibility major complex peptide binding affinity.

Science.gov (United States)

Hattotuwagama, Channa K; Guan, Pingping; Doytchinova, Irini A; Flower, Darren R

2004-11-21

Quantitative structure-activity relationship (QSAR) analysis is a main cornerstone of modern informatic disciplines. Predictive computational models, based on QSAR technology, of peptide-major histocompatibility complex (MHC) binding affinity have now become a vital component of modern day computational immunovaccinology. Historically, such approaches have been built around semi-qualitative, classification methods, but these are now giving way to quantitative regression methods. The additive method, an established immunoinformatics technique for the quantitative prediction of peptide-protein affinity, was used here to identify the sequence dependence of peptide binding specificity for three mouse class I MHC alleles: H2-D(b), H2-K(b) and H2-K(k). As we show, in terms of reliability the resulting models represent a significant advance on existing methods. They can be used for the accurate prediction of T-cell epitopes and are freely available online ( http://www.jenner.ac.uk/MHCPred).

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)

Effects of feedback reliability on feedback-related brain activity: A feedback valuation account.

Science.gov (United States)

Ernst, Benjamin; Steinhauser, Marco

2018-04-06

Adaptive decision making relies on learning from feedback. Because feedback sometimes can be misleading, optimal learning requires that knowledge about the feedback's reliability be utilized to adjust feedback processing. Although previous research has shown that feedback reliability indeed influences feedback processing, the underlying mechanisms through which this is accomplished remain unclear. Here we propose that feedback processing is adjusted by the adaptive, top-down valuation of feedback. We assume that unreliable feedback is devalued relative to reliable feedback, thus reducing the reward prediction errors that underlie feedback-related brain activity and learning. A crucial prediction of this account is that the effects of feedback reliability are susceptible to contrast effects. That is, the effects of feedback reliability should be enhanced when both reliable and unreliable feedback are experienced within the same context, as compared to when only one level of feedback reliability is experienced. To evaluate this prediction, we measured the event-related potentials elicited by feedback in two experiments in which feedback reliability was varied either within or between blocks. We found that the fronto-central valence effect, a correlate of reward prediction errors during reinforcement learning, was reduced for unreliable feedback. But this result was obtained only when feedback reliability was varied within blocks, thus indicating a contrast effect. This suggests that the adaptive valuation of feedback is one mechanism underlying the effects of feedback reliability on feedback processing.

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.

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

Reliability analysis techniques for the design engineer

International Nuclear Information System (INIS)

Corran, E.R.; Witt, H.H.

1980-01-01

A fault tree analysis package is described that eliminates most of the housekeeping tasks involved in proceeding from the initial construction of a fault tree to the final stage of presenting a reliability analysis in a safety report. It is suitable for designers with relatively little training in reliability analysis and computer operation. Users can rapidly investigate the reliability implications of various options at the design stage, and evolve a system which meets specified reliability objectives. Later independent review is thus unlikely to reveal major shortcomings necessitating modification and projects delays. The package operates interactively allowing the user to concentrate on the creative task of developing the system fault tree, which may be modified and displayed graphically. For preliminary analysis system data can be derived automatically from a generic data bank. As the analysis procedes improved estimates of critical failure rates and test and maintenance schedules can be inserted. The computations are standard, - identification of minimal cut-sets, estimation of reliability parameters, and ranking of the effect of the individual component failure modes and system failure modes on these parameters. The user can vary the fault trees and data on-line, and print selected data for preferred systems in a form suitable for inclusion in safety reports. A case history is given - that of HIFAR containment isolation system. (author)

Bayesian approach in the power electric systems study of reliability ...

African Journals Online (AJOL)

Keywords: Reliability - Power System - Bayes Theorem - Weibull Model - Probability. ... ensure a series of estimated parameter (failure rate, mean time to failure, function .... only on random variable r.v. describing the operating conditions: ..... Multivariate performance reliability prediction in real-time, Reliability Engineering.

A taxonomy for human reliability analysis

International Nuclear Information System (INIS)

Beattie, J.D.; Iwasa-Madge, K.M.

1984-01-01

A human interaction taxonomy (classification scheme) was developed to facilitate human reliability analysis in a probabilistic safety evaluation of a nuclear power plant, being performed at Ontario Hydro. A human interaction occurs, by definition, when operators or maintainers manipulate, or respond to indication from, a plant component or system. The taxonomy aids the fault tree analyst by acting as a heuristic device. It helps define the range and type of human errors to be identified in the construction of fault trees, while keeping the identification by different analysts consistent. It decreases the workload associated with preliminary quantification of the large number of identified interactions by including a category called 'simple interactions'. Fault tree analysts quantify these according to a procedure developed by a team of human reliability specialists. The interactions which do not fit into this category are called 'complex' and are quantified by the human reliability team. The taxonomy is currently being used in fault tree construction in a probabilistic safety evaluation. As far as can be determined at this early stage, the potential benefits of consistency and completeness in identifying human interactions and streamlining the initial quantification are being realized

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

Reliability and Validity of the Dyadic Observed Communication Scale (DOCS).

Science.gov (United States)

Hadley, Wendy; Stewart, Angela; Hunter, Heather L; Affleck, Katelyn; Donenberg, Geri; Diclemente, Ralph; Brown, Larry K

2013-02-01

We evaluated the reliability and validity of the Dyadic Observed Communication Scale (DOCS) coding scheme, which was developed to capture a range of communication components between parents and adolescents. Adolescents and their caregivers were recruited from mental health facilities for participation in a large, multi-site family-based HIV prevention intervention study. Seventy-one dyads were randomly selected from the larger study sample and coded using the DOCS at baseline. Preliminary validity and reliability of the DOCS was examined using various methods, such as comparing results to self-report measures and examining interrater reliability. Results suggest that the DOCS is a reliable and valid measure of observed communication among parent-adolescent dyads that captures both verbal and nonverbal communication behaviors that are typical intervention targets. The DOCS is a viable coding scheme for use by researchers and clinicians examining parent-adolescent communication. Coders can be trained to reliably capture individual and dyadic components of communication for parents and adolescents and this complex information can be obtained relatively quickly.

Final Report for the Virtual Reliability Realization System LDRD

Energy Technology Data Exchange (ETDEWEB)

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

2000-12-01

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

Macroscopic travel time reliability diagrams for freeway networks

NARCIS (Netherlands)

Tu, H.; Li, H.; Van Lint, J.W.C.; Knoop, V.L.; Sun, L.

2013-01-01

Travel time reliability is considered to be one of the key indicators of transport system performance. Knowledge of the mechanisms of travel time unreliability enables the derivation of explanatory models with which travel time reliability can be predicted and utilized in traffic management.

Brain morphometric analysis predicts decline of intelligence quotient in children with sickle cell disease: A preliminary study.

Science.gov (United States)

Chen, Rong; Krejza, Jaroslaw; Arkuszewski, Michal; Zimmerman, Robert A; Herskovits, Edward H; Melhem, Elias R

2017-03-01

For children with sickle cell disease (SCD) and at low risk category of stroke, we aim to build a predictive model to differentiate those with decline of intelligence-quotient (IQ) from counterparts without decline, based on structural magnetic-resonance (MR) imaging volumetric analysis. This preliminary prospective cohort study included 25 children with SCD, homozygous for hemoglobin S, with no history of stroke and transcranial Doppler mean velocities below 170cm/s at baseline. We administered the Kaufman Brief Intelligence Test (K-BIT) to each child at yearly intervals for 2-4 years. Each child underwent MR examination within 30 days of the baseline K-BIT evaluation date. We calculated K-BIT change rates, and used rate of change in K-BIT to classify children into two groups: a decline group and a non-decline group. We then generated predictive models to predict K-BIT decline/non-decline based on regional gray-matter (GM) volumes computed from structural MR images. We identified six structures (the left median cingulate gyrus, the right middle occipital gyrus, the left inferior occipital gyrus, the right fusiform gyrus, the right middle temporal gyrus, the right inferior temporal gyrus) that, when assessed for volume at baseline, are jointly predictive of whether a child would suffer subsequent K-BIT decline. Based on these six regional GM volumes and the baseline K-BIT, we built a prognostic model using the K * algorithm. The accuracy, sensitivity and specificity were 0.84, 0.78 and 0.86, respectively. GM volumetric analysis predicts subsequent IQ decline for children with SCD. Copyright © 2017 Medical University of Bialystok. Published by Elsevier B.V. All rights reserved.

A Structured Clinical Interview for Kleptomania (SCI-K): preliminary validity and reliability testing.

Science.gov (United States)

Grant, Jon E; Kim, Suck Won; McCabe, James S

2006-06-01

Kleptomania presents difficulties in diagnosis for clinicians. This study aimed to develop and test a DSM-IV-based diagnostic instrument for kleptomania. To assess for current kleptomania the Structured Clinical Interview for Kleptomania (SCI-K) was administered to 112 consecutive subjects requesting psychiatric outpatient treatment for a variety of disorders. Reliability and validity were determined. Classification accuracy was examined using the longitudinal course of illness. The SCI-K demonstrated excellent test-retest (Phi coefficient = 0.956 (95% CI = 0.937, 0.970)) and inter-rater reliability (phi coefficient = 0.718 (95% CI = 0.506, 0.848)) in the diagnosis of kleptomania. Concurrent validity was observed with a self-report measure using DSM-IV kleptomania criteria (phi coefficient = 0.769 (95% CI = 0.653, 0.850)). Discriminant validity was observed with a measure of depression (point biserial coefficient = -0.020 (95% CI = -0.205, 0.166)). The SCI-K demonstrated both high sensitivity and specificity based on longitudinal assessment. The SCI-K demonstrated excellent reliability and validity in diagnosing kleptomania in subjects presenting with various psychiatric problems. These findings require replication in larger groups, including non-psychiatric populations, to examine their generalizability. Copyright (c) 2006 John Wiley & Sons, Ltd.

Reliability and validity in a nutshell.

Science.gov (United States)

Bannigan, Katrina; Watson, Roger

2009-12-01

To explore and explain the different concepts of reliability and validity as they are related to measurement instruments in social science and health care. There are different concepts contained in the terms reliability and validity and these are often explained poorly and there is often confusion between them. To develop some clarity about reliability and validity a conceptual framework was built based on the existing literature. The concepts of reliability, validity and utility are explored and explained. Reliability contains the concepts of internal consistency and stability and equivalence. Validity contains the concepts of content, face, criterion, concurrent, predictive, construct, convergent (and divergent), factorial and discriminant. In addition, for clinical practice and research, it is essential to establish the utility of a measurement instrument. To use measurement instruments appropriately in clinical practice, the extent to which they are reliable, valid and usable must be established.

Preliminary design of the ITER AC/DC converters supplied by the Korean Domestic Agency

International Nuclear Information System (INIS)

Oh, J.S.; Choi, J.; Suh, J.H.; Liu, H.; Hwang, K.; Chung, I.; Lee, S.; Kang, J.; Park, H.; Jung, W.; Jo, S.; Gweon, H.; Lee, Y.; Lee, W.; Kim, J.B.; Han, S.H.; Hong, G.D.; Lee, J.S.; Lee, B.W.; Yeo, C.H.

2013-01-01

Highlights: ► A self-supporting aluminium structure and symmetrical thyristor assembly are devised to assure a strong and reliable ITER converter. ► Converters are designed to be installable in a compact space with three times higher power density than normal industrial installations. ► Heating of the building structure due to high magnetic field by converters are identified and certain solutions are addressed in the building design. ► A cooperative fast control scheme is adopted to compensate fast reactive power change of up to the level of 900 Mvar. -- Abstract: The preliminary design for ITER AC/DC converters under the responsibility of the Korean Domestic Agency is performed on the basis of the engineering experience of previous R and D for a full-scale 6-pulse CS (Central Solenoid) converter unit. This paper describes key features of the preliminary design for the respective sub-systems; integrated self-supporting aluminium structure and symmetrical thyristor assembly for strong and reliable converters, optimised impedance of the converter transformer to limit short circuit current, coaxial-type AC bus bars to shield high magnetic field around wall penetrations, compact components to fit into given building space. The insulation and the minimisation of electrical loops of concrete rebar below the converter installations are essential to prevent floor heating. Required output voltage or current of converters is provided by a conventional controller. A master controller is designed to collect predicted reactive powers from each converter and deliver processed data to the reactive power compensation (RPC) system to improve the regulation speed of the RPC controller with fast feed-forward compensation under fast reactive power transients

Preliminary design of the ITER AC/DC converters supplied by the Korean Domestic Agency

Energy Technology Data Exchange (ETDEWEB)

Oh, J.S., E-mail: jsoh@nfri.re.kr [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Choi, J.; Suh, J.H. [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Liu, H.; Hwang, K.; Chung, I.; Lee, S.; Kang, J.; Park, H.; Jung, W.; Jo, S.; Gweon, H.; Lee, Y.; Lee, W. [Dawonsys Corp., Siheung 429-450 (Korea, Republic of); Kim, J.B.; Han, S.H.; Hong, G.D.; Lee, J.S.; Lee, B.W.; Yeo, C.H. [Hyosung Corp., 450, Gongdeok-Dong, Seoul 121-720 (Korea, Republic of); and others

2013-10-15

Highlights: ► A self-supporting aluminium structure and symmetrical thyristor assembly are devised to assure a strong and reliable ITER converter. ► Converters are designed to be installable in a compact space with three times higher power density than normal industrial installations. ► Heating of the building structure due to high magnetic field by converters are identified and certain solutions are addressed in the building design. ► A cooperative fast control scheme is adopted to compensate fast reactive power change of up to the level of 900 Mvar. -- Abstract: The preliminary design for ITER AC/DC converters under the responsibility of the Korean Domestic Agency is performed on the basis of the engineering experience of previous R and D for a full-scale 6-pulse CS (Central Solenoid) converter unit. This paper describes key features of the preliminary design for the respective sub-systems; integrated self-supporting aluminium structure and symmetrical thyristor assembly for strong and reliable converters, optimised impedance of the converter transformer to limit short circuit current, coaxial-type AC bus bars to shield high magnetic field around wall penetrations, compact components to fit into given building space. The insulation and the minimisation of electrical loops of concrete rebar below the converter installations are essential to prevent floor heating. Required output voltage or current of converters is provided by a conventional controller. A master controller is designed to collect predicted reactive powers from each converter and deliver processed data to the reactive power compensation (RPC) system to improve the regulation speed of the RPC controller with fast feed-forward compensation under fast reactive power transients.

On reliable discovery of molecular signatures

Directory of Open Access Journals (Sweden)

Björkegren Johan

2009-01-01

Full Text Available Abstract Background Molecular signatures are sets of genes, proteins, genetic variants or other variables that can be used as markers for a particular phenotype. Reliable signature discovery methods could yield valuable insight into cell biology and mechanisms of human disease. However, it is currently not clear how to control error rates such as the false discovery rate (FDR in signature discovery. Moreover, signatures for cancer gene expression have been shown to be unstable, that is, difficult to replicate in independent studies, casting doubts on their reliability. Results We demonstrate that with modern prediction methods, signatures that yield accurate predictions may still have a high FDR. Further, we show that even signatures with low FDR may fail to replicate in independent studies due to limited statistical power. Thus, neither stability nor predictive accuracy are relevant when FDR control is the primary goal. We therefore develop a general statistical hypothesis testing framework that for the first time provides FDR control for signature discovery. Our method is demonstrated to be correct in simulation studies. When applied to five cancer data sets, the method was able to discover molecular signatures with 5% FDR in three cases, while two data sets yielded no significant findings. Conclusion Our approach enables reliable discovery of molecular signatures from genome-wide data with current sample sizes. The statistical framework developed herein is potentially applicable to a wide range of prediction problems in bioinformatics.

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

A discussion of system reliability and the relative importance of pumps and valves to overall system availability

Energy Technology Data Exchange (ETDEWEB)

Poole, A.B. [Oak Ridge National Lab., TN (United States)

1996-12-01

An analysis was undertaken to establish preliminary trends for how component aging can effect failure rates for swing check valves, centrifugal pumps and motor operated valves. These failure rate trends were evaluated over time and linear aging rate models established. The failure rate models were then used with classic reliability theories to estimate reliability as a function of operating time. Reliability theory was also used to establish a simple system reliability model. Using the system model, the relative importance of pumps and valves to the overall system reliability were studied. Conclusions were established relative to overall system availability over time and the relative unavailabilities of the various components studied.

A discussion of system reliability and the relative importance of pumps and valves to overall system availability

International Nuclear Information System (INIS)

Poole, A.B.

1996-01-01

An analysis was undertaken to establish preliminary trends for how component aging can effect failure rates for swing check valves, centrifugal pumps and motor operated valves. These failure rate trends were evaluated over time and linear aging rate models established. The failure rate models were then used with classic reliability theories to estimate reliability as a function of operating time. Reliability theory was also used to establish a simple system reliability model. Using the system model, the relative importance of pumps and valves to the overall system reliability were studied. Conclusions were established relative to overall system availability over time and the relative unavailabilities of the various components studied

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

Reliability analysis of shutdown system

International Nuclear Information System (INIS)

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

2005-01-01

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

Design for Reliability of Power Electronic Systems

DEFF Research Database (Denmark)

Wang, Huai; Ma, Ke; Blaabjerg, Frede

2012-01-01

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

Preliminary result on trabecular bone score (TBS in lumbar vertebrae with experimentally altered microarchitecture

Directory of Open Access Journals (Sweden)

M. Di Stefano

2013-01-01

Full Text Available The aim of this preliminary research is to investigate the reliability of a new qualitative parameter, called Trabecular Bone Score (TBS, recently proposed for evaluating the microarchitectural arrangement of cancellous bone in scans carried out by dual energy X-ray absorptiometry (DXA. Vertebral bodies of 15 fresh samples of lumbar spines of adult pig were analysed either in basal conditions and with altered microarchitecture of the cancellous bone obtained by progressive drilling. The examined bony areas do not show changes in bone mineral density (BMD, whereas TBS values decrease with the increasing alteration of the vertebral microtrabecular structure. Our preliminary data seem to confirm the reliability of TBS as a qualitative parameter useful for evaluating the microarchitectural strength in bony areas quantitatively analysed by DXA.

Integration of NDE Reliability and Fracture Mechanics

Energy Technology Data Exchange (ETDEWEB)

Becker, F. L.; Doctor, S. R.; Heas!er, P. G.; Morris, C. J.; Pitman, S. G.; Selby, G. P.; Simonen, F. A.

1981-03-01

The Pacific Northwest Laboratory is conducting a four-phase program for measuring and evaluating the effectiveness and reliability of in-service inspection (lSI} performed on the primary system piping welds of commercial light water reactors (LWRs). Phase I of the program is complete. A survey was made of the state of practice for ultrasonic rsr of LWR primary system piping welds. Fracture mechanics calculations were made to establish required nondestrutive testing sensitivities. In general, it was found that fatigue flaws less than 25% of wall thickness would not grow to failure within an inspection interval of 10 years. However, in some cases failure could occur considerably faster. Statistical methods for predicting and measuring the effectiveness and reliability of lSI were developed and will be applied in the "Round Robin Inspections" of Phase II. Methods were also developed for the production of flaws typical of those found in service. Samples fabricated by these methods wilI be used in Phase II to test inspection effectiveness and reliability. Measurements were made of the influence of flaw characteristics {i.e., roughness, tightness, and orientation) on inspection reliability. These measurernents, as well as the predictions of a statistical model for inspection reliability, indicate that current reporting and recording sensitivities are inadequate.

Establishing Reliability and Construct Validity for an Instrument to Measure Environmental Connectedness

Science.gov (United States)

Beery, Thomas H.

2013-01-01

The purpose of this preliminary study is to establish a reliable and valid measure of environmental connectedness (EC) to allow for further exploration of the Swedish Outdoor Recreation in Change national survey data. The Nordic concept of friluftsliv (nature-based outdoor recreation) and the environmental psychology concept of EC are explored to…

Use of eye tracking equipment for human reliability analysis applied to complex system operations

International Nuclear Information System (INIS)

Pinheiro, Andre Ricardo Mendonça; Prado, Eugenio Anselmo Pessoa do; Martins, Marcelo Ramos

2017-01-01

This article will discuss the preliminary results of an evaluation methodology for the analysis and quantification of manual character errors (human), by monitoring cognitive parameters and skill levels in the operation of a complex control system based on parameters provided by a eye monitoring equipment (Eye Tracker). The research was conducted using a simulator (game) that plays concepts of operation of a nuclear reactor with a split sample for evaluation of aspects of learning, knowledge and standard operating within the context addressed. bridge operators were monitored using the EYE TRACKING, eliminating the presence of the analyst in the evaluation of the operation, allowing the analysis of the results by means of multivariate statistical techniques within the scope of system reliability. The experiments aim to observe state change situations such as stops and scheduled departures, incidents assumptions and common operating characteristics. Preliminary results of this research object indicate that technical and cognitive aspects can contribute to improving the reliability of the available techniques in human reliability, making them more realistic both in the context of quantitative approaches to regulatory and training purposes, as well as reduced incidence of human error. (author)

Use of eye tracking equipment for human reliability analysis applied to complex system operations

Energy Technology Data Exchange (ETDEWEB)

Pinheiro, Andre Ricardo Mendonça; Prado, Eugenio Anselmo Pessoa do; Martins, Marcelo Ramos, E-mail: andrericardopinheiro@usp.br, E-mail: eugenio.prado@labrisco.usp.br, E-mail: mrmatins@usp.br [Universidade de Sao Paulo (LABRISCO/USP), Sao Paulo, SP (Brazil). Lab. de Análise, Avaliação e Gerenciamento de Risco

2017-07-01

This article will discuss the preliminary results of an evaluation methodology for the analysis and quantification of manual character errors (human), by monitoring cognitive parameters and skill levels in the operation of a complex control system based on parameters provided by a eye monitoring equipment (Eye Tracker). The research was conducted using a simulator (game) that plays concepts of operation of a nuclear reactor with a split sample for evaluation of aspects of learning, knowledge and standard operating within the context addressed. bridge operators were monitored using the EYE TRACKING, eliminating the presence of the analyst in the evaluation of the operation, allowing the analysis of the results by means of multivariate statistical techniques within the scope of system reliability. The experiments aim to observe state change situations such as stops and scheduled departures, incidents assumptions and common operating characteristics. Preliminary results of this research object indicate that technical and cognitive aspects can contribute to improving the reliability of the available techniques in human reliability, making them more realistic both in the context of quantitative approaches to regulatory and training purposes, as well as reduced incidence of human error. (author)

The Children's Play Therapy Instrument (CPTI). Description, development, and reliability studies.

Science.gov (United States)

Kernberg, P F; Chazan, S E; Normandin, L

1998-01-01

The Children's Play Therapy Instrument (CPTI), its development, and reliability studies are described. The CPTI is a new instrument to examine a child's play activity in individual psychotherapy. Three independent raters used the CPTI to rate eight videotaped play therapy vignettes. Results were compared with the authors' consensual scores from a preliminary study. Generally good to excellent levels of interrater reliability were obtained for the independent raters on intraclass correlation coefficients for ordinal categories of the CPTI. Likewise, kappa levels were acceptable to excellent for nominal categories of the scale. The CPTI holds promise to become a reliable measure of play activity in child psychotherapy. Further research is needed to assess discriminant validity of the CPTI for use as a diagnostic tool and as a measure of process and outcome.

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

A Reliability-Oriented Design Method for Power Electronic Converters

DEFF Research Database (Denmark)

Wang, Huai; Zhou, Dao; Blaabjerg, Frede

2013-01-01

Reliability is a crucial performance indicator of power electronic systems in terms of availability, mission accomplishment and life cycle cost. A paradigm shift in the research on reliability of power electronics is going on from simple handbook based calculations (e.g. models in MIL-HDBK-217F h...... and reliability prediction models are provided. A case study on a 2.3 MW wind power converter is discussed with emphasis on the reliability critical component IGBT modules....

A Prediction Study of Aluminum Alloy Oxidation of the Fuel Cladding in Jordan Research and Training Reactor

Energy Technology Data Exchange (ETDEWEB)

Tahk, Y. W.; Oh, J. Y.; Lee, B. H.; Seo, C. G.; Chae, H. T.; Yim, J. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-10-15

U{sub 3}Si{sub 2}-Al dispersion fuel with Al cladding will be used for Jordan Research and Training Reactor (JRTR). Aluminum alloy cladding experiences the oxidation layer growth on the surface during the reactor operation. The formation of oxides on the cladding affects fuel performance by increasing fuel temperature. According to the current JRTR fuel management scheme and operation strategy for 5 MW power, a fresh fuel is discharged after 900 effective full power days (EFPD) with 18 cycles of 50 days loading. For the proper prediction of the aluminum oxide thickness of fuel cladding during the long residence time, a reliable model is needed. In this work, several oxide thickness prediction models are compared with the measured data from in-pile test by RERTR program. Moreover, specific parametric studies and a preliminary prediction of the aluminum alloy oxidation using the latest model are performed for JRTR fuel

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.

Integrated reliability condition monitoring and maintenance of equipment

CERN Document Server

Osarenren, John

2015-01-01

Consider a Viable and Cost-Effective Platform for the Industries of the Future (IOF) Benefit from improved safety, performance, and product deliveries to your customers. Achieve a higher rate of equipment availability, performance, product quality, and reliability. Integrated Reliability: Condition Monitoring and Maintenance of Equipment incorporates reliable engineering and mathematical modeling to help you move toward sustainable development in reliability condition monitoring and maintenance. This text introduces a cost-effective integrated reliability growth monitor, integrated reliability degradation monitor, technological inheritance coefficient sensors, and a maintenance tool that supplies real-time information for predicting and preventing potential failures of manufacturing processes and equipment. The author highlights five key elements that are essential to any improvement program: improving overall equipment and part effectiveness, quality, and reliability; improving process performance with maint...

Load As A Reliability Resource in the Restructured Electricity Market

Energy Technology Data Exchange (ETDEWEB)

Kueck, J.D.

2002-06-10

Recent electricity price spikes are painful reminders of the value that meaningful demand-side responses could bring to the restructuring US electricity system. Review of the aggregate offers made by suppliers confirms that even a modest increase in demand elasticity could dramatically reduce these extremes in price volatility. There is a strong need for dramatically increased customer participation in these markets to enhance system reliability and reduce price volatility. Indeed, allowing customers to manage their loads in response to system conditions might be thought of as the ultimate reliability resource. Most would agree that meaningful demand-side responses to price are the hallmark of a well-functioning competitive market [1]. Yet, in today's markets for electricity, little or no such response is evident. The reason is simple: customers currently do not experience directly the time-varying costs of their consumption decisions. Consequently, they have no incentive to modify these decisions in ways that might enhance system reliability or improve the efficiency of the markets in which electricity is traded. Increased customer participation is a necessary step in the evolution toward more efficient markets for electricity and ancillary services. This scoping report provides a three-part assessment of the current status of efforts to enhance the ability of customer's load to participate in competitive markets with a specific focus on the role of customer loads in enhancing electricity system reliability. First, this report considers the definitions of electricity-reliability-enhancing ancillary services (Section 2) and a preliminary assessment of the ability of customer's loads to provide these services. Second, is a review a variety of programs in which load has been called on as a system reliability resource (Section 3). These experiences, drawn from both past and current utility and ISO programs, focus on programs triggered by system

Preliminary I&C Design for LORELEI

International Nuclear Information System (INIS)

Korotkin, S.; Kaufman, Y.; Guttmann, E. B.; Levy, S.; Amidan, D.; Gdalyho, B.; Cahana, T.; Ellenbogen, A.; Arad, M.; Weiss, Y.; Sasson, A.; Ferry, L.; Bourrelly, F.; Cohen, Y.

2014-01-01

This document summarizes the preliminary I&C design for LORELEI experiment The preliminary design deals with considerations regarding appropriate safety and service instrumentation. The determined closed loop control rules for temperature and position will be implemented in the detailed design. The Computer Aided Operator Decisions System (CAODS) will be used for prediction of hot spot temperature and thickness of oxidation layer using Baker-Just correlation. The proposed hybrid simulation system comprising of both virtual and real hardware will be in-cooperated for LORELEI verification. It will perform both integration cold tests for a partial hardware loop and virtual tests for the final I&C design

Measuring time and risk preferences: Reliability, stability, domain specificity

NARCIS (Netherlands)

Wölbert, E.M.; Riedl, A.M.

2013-01-01

To accurately predict behavior economists need reliable measures of individual time preferences and attitudes toward risk and typically need to assume stability of these characteristics over time and across decision domains. We test the reliability of two choice tasks for eliciting discount rates,

Impact of staffing parameters on operational reliability

International Nuclear Information System (INIS)

Hahn, H.A.; Houghton, F.K.

1993-01-01

This paper reports on a project related to human resource management of the Department of Energy's (DOE's) High-Level Waste (HLW) Tank program. Safety and reliability of waste tank operations is impacted by several issues, including not only the design of the tanks themselves, but also how operations and operational personnel are managed. As demonstrated by management assessments performed by the Tiger Teams, DOE believes that the effective use of human resources impacts environment safety, and health concerns. For the of the current paper, human resource management activities are identified as ''Staffing'' and include the of developing the functional responsibilities and qualifications of technical and administrative personnel. This paper discusses the importance of staff plans and management in the overall view of safety and reliability. The work activities and procedures associated with the project, a review of the results of these activities, including a summary of the literature and a preliminary analysis of the data. We conclude that although identification of staffing issues and the development of staffing plans contributes to the overall reliability and safety of the HLW tanks, the relationship is not well understood and is in need of further development

Impact of staffing parameters on operational reliability

International Nuclear Information System (INIS)

Hahn, H.A.; Houghton, F.K.

1993-01-01

This paper reports on a project related to human resource management of the Department of Energy (DOEs) High-Level Waste (HLW) Tank program. Safety and reliability of waste tank operations is impacted by several issues, including not only the design of the tanks themselves, but also how operations and operational personnel are managed. As demonstrated by management assessments performed by the Tiger Teams, DOE believes that the effective use of human resources impacts environment, safety, and health concerns. For the purposes of the current paper, human resource management activities are identified as 'Staffing' and include the process of developing the functional responsibilities and qualifications of technical and administrative personnel. This paper discusses the importance of staff plans and management in the overall view of safety and reliability, the work activities and procedures associated with the project, a review of the results of these activities, including a summary of the literature and a preliminary analysis of the data. We conclude that, although identification of staffing issues and the development of staffing plans contributes to the overall reliability and safety of the HLW tanks, the relationship is not well understood and is in need of further development

Increasing of prediction reliability of calcium carbonate scale formation in heat exchanger of secondary coolant circuits of thermal and nuclear power plants

International Nuclear Information System (INIS)

Tret'yakov, O.V.; Kritskij, V.G.; Styazhkin, P.S.

1991-01-01

Calcium carbonate scale formation in the secondary circuit heat exchanger of thermal and nuclear power plants is investigated. A model of calcium-carbonate scale formation providing quite reliable prediction of process running and the possibility of its control affecting the parameters of hydrochemical regime (HCR) is developed. The results can be used when designing the automatic-control system of HCR

Trade-offs in size, quantity and reliability of generalized nuclear power plants: a preliminary assessment

International Nuclear Information System (INIS)

Hill, D.

1985-04-01

An approximate method is used to estimate the effects of system reliability on optimal nuclear plant size, taking into account also scale factors and manufacturing learning curve slopes. The method is used to estimate the additional effective capability gained by adding units of different sizes to an existing electrical system. The number of additional units proves to be sensitive to forced outrage rate, estimated here from trends in US light-water reactors from 1971 to 1980. The relative cost of added units ranging in size from 200 to 800 MW is determined as a function of the parameters: scale factor and learning curve slope. The results generally corrobate the trends found in an earlier study in which the effect of reliability on required installed capacity was not explicitly considered. Optimal plant size decreases with weaker scale effects and stronger learning curve effects. Reliability considerations further reduce the optimal plant size, but the relative reduction is apparently not as great with steeper learning curves. This is a plausible finding inasmuch as the reduction in numbers of additional units due to reliability considerations will affect cost most where the learning curve is steepest. 9 refs., 4 figs., 3 tabs

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.

Supply reliability in context to quality regulation. Forecast model for the supply reliability; Versorgungszuverlaessigkeit im Kontext der Qualitaetsregulierung. Prognosemodell fuer die Versorgungszuverlaessigkeit

Energy Technology Data Exchange (ETDEWEB)

Quadflieg, Dieter [VDE, Berlin (Germany). FNN-Projektgruppe ' ' Einflussgroessen auf die Versorgungszuverlaessigkeit' '

2011-11-14

The forum network technology / network operations in VDE (FNN) has published a technical note on supply reliability in the context of quality regulation. In the underlying investigations, on the one hand the influencing variables on the supply reliability are analyzed on the basis of FNN fault and availability statistics. On the other stochastic methods are developed that allow a prediction of the stochastic reliability characteristics of each network operator.

Individual differences in fluid intelligence predicts inattentional blindness in a sample of older adults: a preliminary study.

Science.gov (United States)

O'Shea, Deirdre M; Fieo, Robert A

2015-07-01

Previous research has shown that aging increases susceptibility to inattentional blindness (Graham and Burke, Psychol Aging 26:162, 2011) as well as individual differences in cognitive ability related to working memory and executive functions in separate studies. Therefore, the present study was conducted in an attempt to bridge a gap that involved investigating 'age-sensitive' cognitive abilities that may predict inattentional blindness in a sample of older adults. We investigated whether individual differences in general fluid intelligence and speed of processing would predict inattentional blindness in our sample of older adults. Thirty-six healthy older adults took part in the study. Using the inattentional blindness paradigm developed by Most et al. (Psychol Rev 112:217, 2005), we investigated whether rates of inattentional blindness could be predicted by participant's performance on the Raven's Advanced Progressive Matrices and a choice-reaction time task. A Mann-Whitney U test revealed that a higher score on the Raven's Advanced Progressive Matrices was significantly associated with lower incidences of inattentional blindness. However, a t test revealed that choice-reaction times were not significantly associated with inattentional blindness. Preliminary results from the present study suggest that individual differences in general fluid intelligence are predictive of inattentional blindness in older adults but not speed of processing. Moreover, our findings are consistent with previous studies that have suggested executive attention control may be the source of these individual differences. These findings also highlight the association between attention and general fluid intelligence and how it may impact environmental awareness. Future research would benefit from repeating these analyses in a larger sample and also including a younger comparison group.

Quality and reliability management and its applications

CERN Document Server

2016-01-01

Integrating development processes, policies, and reliability predictions from the beginning of the product development lifecycle to ensure high levels of product performance and safety, this book helps companies overcome the challenges posed by increasingly complex systems in today’s competitive marketplace.   Examining both research on and practical aspects of product quality and reliability management with an emphasis on applications, the book features contributions written by active researchers and/or experienced practitioners in the field, so as to effectively bridge the gap between theory and practice and address new research challenges in reliability and quality management in practice.    Postgraduates, researchers and practitioners in the areas of reliability engineering and management, amongst others, will find the book to offer a state-of-the-art survey of quality and reliability management and practices.

Operational reliability management; Gestao da confiabilidade operacional

Energy Technology Data Exchange (ETDEWEB)

Bressan, Edemir [Refinaria Alberto Pasqualini (REFAP), Canoas, RS (Brazil). Setor de Tecnologia de Equipamentos

2000-07-01

It is described the PETROBRAS Alberto Pasqualini Refinery process plant reliability management, strategies, maintenance organizational structure, management processes, predictive and preventive maintenance, condition monitoring techniques, reliability metrics, pointing out a need for close work relationship between production, maintenance and project engineering functions with highly qualified and committed proper teams, in order to reach one of the highest mechanical availability among Latin America refineries. (author)

Failure database and tools for wind turbine availability and reliability analyses. The application of reliability data for selected wind turbines

DEFF Research Database (Denmark)

Kozine, Igor; Christensen, P.; Winther-Jensen, M.

2000-01-01

The objective of this project was to develop and establish a database for collecting reliability and reliability-related data, for assessing the reliability of wind turbine components and subsystems and wind turbines as a whole, as well as for assessingwind turbine availability while ranking the ...... similar safety systems. The database was established with Microsoft Access DatabaseManagement System, the software for reliability and availability assessments was created with Visual Basic....... the contributions at both the component and system levels. The project resulted in a software package combining a failure database with programs for predicting WTB availability and the reliability of all thecomponents and systems, especially the safety system. The report consists of a description of the theoretical......The objective of this project was to develop and establish a database for collecting reliability and reliability-related data, for assessing the reliability of wind turbine components and subsystems and wind turbines as a whole, as well as for assessingwind turbine availability while ranking...

People consider reliability and cost when verifying their autobiographical memories.

Science.gov (United States)

Wade, Kimberley A; Nash, Robert A; Garry, Maryanne

2014-02-01

Because memories are not always accurate, people rely on a variety of strategies to verify whether the events that they remember really did occur. Several studies have examined which strategies people tend to use, but none to date has asked why people opt for certain strategies over others. Here we examined the extent to which people's beliefs about the reliability and the cost of different strategies would determine their strategy selection. Subjects described a childhood memory and then suggested strategies they might use to verify the accuracy of that memory. Next, they rated the reliability and cost of each strategy, and the likelihood that they might use it. Reliability and cost each predicted strategy selection, but a combination of the two ratings provided even greater predictive value. Cost was significantly more influential than reliability, which suggests that a tendency to seek and to value "cheap" information more than reliable information could underlie many real-world memory errors. Copyright © 2013 Elsevier B.V. All rights reserved.

Steam generator reliability improvement project

International Nuclear Information System (INIS)

Blomgren, J.C.; Green, S.J.

1987-01-01

Upon successful completion of its research and development technology transfer program, the Electric Power Research Institute's Steam Generator Owners Group (SGOG II) will disband in December 1986 and be replaced in January 1987 by a successor project, the Steam Generator Reliability Project (SGRP). The new project, funded in the EPRI base program, will continue the emphasis on reliability and life extension that was carried forward by SGOG II. The objectives of SGOG II have been met. Causes and remedies have been identified for tubing corrosion problems, such as stress corrosion cracking and pitting, and steam generator technology has been improved in areas such as tube wear prediction and nondestructive evaluation (NDE). These actions have led to improved reliability of steam generators. Now the owners want to continue with a centrally managed program that builds on what has been learned. The goal is to continue to improve steam generator reliability and solve small problems before they become large problems

Steam generator reliability improvement project

International Nuclear Information System (INIS)

Blomgren, J.C.; Green, S.J.

1987-01-01

Upon successful completion of its research and development technology transfer program, the Electric Power Research Institute's (EPRI's) Steam Generator Owners Group (SGOG II) will disband in December 1986, and be replaced in January 1987, by a successor project, the Steam Generator Reliability Project (SGRP). The new project, funded in the EPRI base program, will continue to emphasize reliability and life extension, which were carried forward by SGOG II. The objectives of SGOG II have been met. Causes and remedies have been identified for tubing corrosion problems such as stress corrosion cracking and pitting, and steam generator technology has been improved in areas such as tube wear prediction and nondestructive evaluation. These actions have led to improved reliability of steam generators. Now the owners want to continue with a centrally managed program that builds on what has been learned. The goal is to continue to improve steam generator reliability and to solve small problems before they become large problems

Forecasting reliability of transformer populations

NARCIS (Netherlands)

Schijndel, van A.; Wetzer, J.; Wouters, P.A.A.F.

2007-01-01

The expected replacement wave in the current power grid faces asset managers with challenging questions. Setting up a replacement strategy and planning calls for a forecast of the long term component reliability. For transformers the future failure probability can be predicted based on the ongoing

The consultation and relational empathy (CARE) measure: development and preliminary validation and reliability of an empathy-based consultation process measure.

Science.gov (United States)

Mercer, Stewart W; Maxwell, Margaret; Heaney, David; Watt, Graham Cm

2004-12-01

Empathy is a key aspect of the clinical encounter but there is a lack of patient-assessed measures suitable for general clinical settings. Our aim was to develop a consultation process measure based on a broad definition of empathy, which is meaningful to patients irrespective of their socio-economic background. Qualitative and quantitative approaches were used to develop and validate the new measure, which we have called the consultation and relational empathy (CARE) measure. Concurrent validity was assessed by correlational analysis against other validated measures in a series of three pilot studies in general practice (in areas of high or low socio-economic deprivation). Face and content validity was investigated by 43 interviews with patients from both types of areas, and by feedback from GPs and expert researchers in the field. The initial version of the new measure (pilot 1; high deprivation practice) correlated strongly (r = 0.85) with the Reynolds empathy measure (RES) and the Barrett-Lennard empathy subscale (BLESS) (r = 0.63), but had a highly skewed distribution (skew -1.879, kurtosis 3.563). Statistical analysis, and feedback from the 20 patients interviewed, the GPs and the expert researchers, led to a number of modifications. The revised, second version of the CARE measure, tested in an area of low deprivation (pilot 2) also correlated strongly with the established empathy measures (r = 0.84 versus RES and r = 0.77 versus BLESS) but had a less skewed distribution (skew -0.634, kurtosis -0.067). Internal reliability of the revised version was high (Cronbach's alpha 0.92). Patient feedback at interview (n = 13) led to only minor modification. The final version of the CARE measure, tested in pilot 3 (high deprivation practice) confirmed the validation with the other empathy measures (r = 0.85 versus RES and r = 0.84 versus BLESS) and the face validity (feedback from 10 patients). These preliminary results support the validity and reliability of the CARE

A web-based team-oriented medical error communication assessment tool: development, preliminary reliability, validity, and user ratings.

Science.gov (United States)

Kim, Sara; Brock, Doug; Prouty, Carolyn D; Odegard, Peggy Soule; Shannon, Sarah E; Robins, Lynne; Boggs, Jim G; Clark, Fiona J; Gallagher, Thomas

2011-01-01

Multiple-choice exams are not well suited for assessing communication skills. Standardized patient assessments are costly and patient and peer assessments are often biased. Web-based assessment using video content offers the possibility of reliable, valid, and cost-efficient means for measuring complex communication skills, including interprofessional communication. We report development of the Web-based Team-Oriented Medical Error Communication Assessment Tool, which uses videotaped cases for assessing skills in error disclosure and team communication. Steps in development included (a) defining communication behaviors, (b) creating scenarios, (c) developing scripts, (d) filming video with professional actors, and (e) writing assessment questions targeting team communication during planning and error disclosure. Using valid data from 78 participants in the intervention group, coefficient alpha estimates of internal consistency were calculated based on the Likert-scale questions and ranged from α=.79 to α=.89 for each set of 7 Likert-type discussion/planning items and from α=.70 to α=.86 for each set of 8 Likert-type disclosure items. The preliminary test-retest Pearson correlation based on the scores of the intervention group was r=.59 for discussion/planning and r=.25 for error disclosure sections, respectively. Content validity was established through reliance on empirically driven published principles of effective disclosure as well as integration of expert views across all aspects of the development process. In addition, data from 122 medicine and surgical physicians and nurses showed high ratings for video quality (4.3 of 5.0), acting (4.3), and case content (4.5). Web assessment of communication skills appears promising. Physicians and nurses across specialties respond favorably to the tool.

Reliability Analysis for Safety Grade PLC(POSAFE-Q)

International Nuclear Information System (INIS)

Choi, Kyung Chul; Song, Seung Whan; Park, Gang Min; Hwang, Sung Jae

2012-01-01

Safety Grade PLC(Programmable Logic Controller), POSAFE-Q, was developed recently in accordance with nuclear regulatory and requirements. In this paper, describe reliability analysis for digital safety grade PLC (especially POSAFE-Q). Reliability analysis scope is Prediction, Calculation of MTBF (Mean Time Between Failure), FMEA (Failure Mode Effect Analysis), PFD (Probability of Failure on Demand). (author)

A novel attention training paradigm based on operant conditioning of eye gaze: Preliminary findings.

Science.gov (United States)

Price, Rebecca B; Greven, Inez M; Siegle, Greg J; Koster, Ernst H W; De Raedt, Rudi

2016-02-01

Inability to engage with positive stimuli is a widespread problem associated with negative mood states across many conditions, from low self-esteem to anhedonic depression. Though attention retraining procedures have shown promise as interventions in some clinical populations, novel procedures may be necessary to reliably attenuate chronic negative mood in refractory clinical populations (e.g., clinical depression) through, for example, more active, adaptive learning processes. In addition, a focus on individual difference variables predicting intervention outcome may improve the ability to provide such targeted interventions efficiently. To provide preliminary proof-of-principle, we tested a novel paradigm using operant conditioning to train eye gaze patterns toward happy faces. Thirty-two healthy undergraduates were randomized to receive operant conditioning of eye gaze toward happy faces (train-happy) or neutral faces (train-neutral). At the group level, the train-happy condition attenuated sad mood increases following a stressful task, in comparison to train-neutral. In individual differences analysis, greater physiological reactivity (pupil dilation) in response to happy faces (during an emotional face-search task at baseline) predicted decreased mood reactivity after stress. These Preliminary results suggest that operant conditioning of eye gaze toward happy faces buffers against stress-induced effects on mood, particularly in individuals who show sufficient baseline neural engagement with happy faces. Eye gaze patterns to emotional face arrays may have a causal relationship with mood reactivity. Personalized medicine research in depression may benefit from novel cognitive training paradigms that shape eye gaze patterns through feedback. Baseline neural function (pupil dilation) may be a key mechanism, aiding in iterative refinement of this approach. (c) 2016 APA, all rights reserved).

Validity and Reliability Study of the Korean Tinetti Mobility Test for Parkinson's Disease.

Science.gov (United States)

Park, Jinse; Koh, Seong-Beom; Kim, Hee Jin; Oh, Eungseok; Kim, Joong-Seok; Yun, Ji Young; Kwon, Do-Young; Kim, Younsoo; Kim, Ji Seon; Kwon, Kyum-Yil; Park, Jeong-Ho; Youn, Jinyoung; Jang, Wooyoung

2018-01-01

Postural instability and gait disturbance are the cardinal symptoms associated with falling among patients with Parkinson's disease (PD). The Tinetti mobility test (TMT) is a well-established measurement tool used to predict falls among elderly people. However, the TMT has not been established or widely used among PD patients in Korea. The purpose of this study was to evaluate the reliability and validity of the Korean version of the TMT for PD patients. Twenty-four patients diagnosed with PD were enrolled in this study. For the interrater reliability test, thirteen clinicians scored the TMT after watching a video clip. We also used the test-retest method to determine intrarater reliability. For concurrent validation, the unified Parkinson's disease rating scale, Hoehn and Yahr staging, Berg Balance Scale, Timed-Up and Go test, 10-m walk test, and gait analysis by three-dimensional motion capture were also used. We analyzed receiver operating characteristic curve to predict falling. The interrater reliability and intrarater reliability of the Korean Tinetti balance scale were 0.97 and 0.98, respectively. The interrater reliability and intra-rater reliability of the Korean Tinetti gait scale were 0.94 and 0.96, respectively. The Korean TMT scores were significantly correlated with the other clinical scales and three-dimensional motion capture. The cutoff values for predicting falling were 14 points (balance subscale) and 10 points (gait subscale). We found that the Korean version of the TMT showed excellent validity and reliability for gait and balance and had high sensitivity and specificity for predicting falls among patients with PD.

Bayesian methodology for reliability model acceptance

International Nuclear Information System (INIS)

Zhang Ruoxue; Mahadevan, Sankaran

2003-01-01

This paper develops a methodology to assess the reliability computation model validity using the concept of Bayesian hypothesis testing, by comparing the model prediction and experimental observation, when there is only one computational model available to evaluate system behavior. Time-independent and time-dependent problems are investigated, with consideration of both cases: with and without statistical uncertainty in the model. The case of time-independent failure probability prediction with no statistical uncertainty is a straightforward application of Bayesian hypothesis testing. However, for the life prediction (time-dependent reliability) problem, a new methodology is developed in this paper to make the same Bayesian hypothesis testing concept applicable. With the existence of statistical uncertainty in the model, in addition to the application of a predictor estimator of the Bayes factor, the uncertainty in the Bayes factor is explicitly quantified through treating it as a random variable and calculating the probability that it exceeds a specified value. The developed method provides a rational criterion to decision-makers for the acceptance or rejection of the computational model

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

Science.gov (United States)

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

1994-01-01

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

Influence of study satisfaction on academic procrastination in psychology students: a preliminary study

Directory of Open Access Journals (Sweden)

Sergio Alexis Dominguez-Lara

2017-06-01

Full Text Available The aim of this predictive study was to analyze the degree of influence of study satisfaction (SS on academic procrastination (AP. One hundred forty- eight (148 psychology students (111 women between 18 and 32 years old (M = 22.41 were evaluated using the Brief Scale of Study Satisfaction and the Academic Procrastination Scale. After preliminary analyses focused on the scores reliability (α > 0.70 and correlations between dimensions, a regression analysis was performed to determine how much of the variability in the AP dimensions’ scores is explained by the variations in the SS. For that purpose, a method that uses bivariate correlations corrected for attenuation and provides confidence intervals under a bootstrap approach of the associated statistics was applied. All analyses were assessed from an effect size approach. The results indicate that the influence of SS on AP was not significant. These findings provide new ways to implement studies in order to understand the procrastinating behavior in the university setting.

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...

A reliability evaluation method for NPP safety DCS application software

International Nuclear Information System (INIS)

Li Yunjian; Zhang Lei; Liu Yuan

2014-01-01

In the field of nuclear power plant (NPP) digital i and c application, reliability evaluation for safety DCS application software is a key obstacle to be removed. In order to quantitatively evaluate reliability of NPP safety DCS application software, this paper propose a reliability evaluating method based on software development life cycle every stage's v and v defects density characteristics, by which the operating reliability level of the software can be predicted before its delivery, and helps to improve the reliability of NPP safety important software. (authors)

Criteria for safety related nuclear plant operator actions: a preliminary assessment of available data

International Nuclear Information System (INIS)

Haas, P.M.; Bott, T.F.

1982-01-01

The need for a quantitative data base on the reliability of nuclear power plant operators has long been recognised by human factors and reliability analysts, and the great need for further assessment of operator performance under accident conditions has been dramatically emphasised by the incident at Three Mile Island-2. In the US, an effort has been under way for a number of years to develop a design standard to define when required manual operator action can be accepted as part of a nuclear plant design basis. To provide the necessary data base to support such standards and the necessary quantitative assessment of operator reliability, the US Nuclear Regulatory Commission is sponsoring a study at Oak Ridge National Laboratory to develop the data base. A preliminary assessment, completed in April 1979, concluded that sufficient data from US operating experience did not exist to provide an adequate data base. A programme of research using full-scope nuclear plant simulators and results that are correlated to field data was suggested. That programme was recently initiated. This paper reviews the approach, results and conclusions of the preliminary assessment and summarises the planned research programme of simulator studies. (author)

Reliability metrics extraction for power electronics converter stressed by thermal cycles

DEFF Research Database (Denmark)

Ma, Ke; Choi, Uimin; Blaabjerg, Frede

2017-01-01

Due to the continuous demands for highly reliable and cost-effective power conversion, the quantified reliability performances of the power electronics converter are becoming emerging needs. The existing reliability modelling approaches for the power electronics converter mainly focuses on the pr...... performance of power electronics system. The final predicted results showed good accuracy with much more reliability information compared to the existing approaches, and the quantified reliability correlation to the mission profiles of converter is mathematically established....

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.

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

A Bayesian reliability evaluation method with integrated accelerated degradation testing and field information

International Nuclear Information System (INIS)

Wang, Lizhi; Pan, Rong; Li, Xiaoyang; Jiang, Tongmin

2013-01-01

Accelerated degradation testing (ADT) is a common approach in reliability prediction, especially for products with high reliability. However, oftentimes the laboratory condition of ADT is different from the field condition; thus, to predict field failure, one need to calibrate the prediction made by using ADT data. In this paper a Bayesian evaluation method is proposed to integrate the ADT data from laboratory with the failure data from field. Calibration factors are introduced to calibrate the difference between the lab and the field conditions so as to predict a product's actual field reliability more accurately. The information fusion and statistical inference procedure are carried out through a Bayesian approach and Markov chain Monte Carlo methods. The proposed method is demonstrated by two examples and the sensitivity analysis to prior distribution assumption

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.

Reliability of application of inspection procedures

Energy Technology Data Exchange (ETDEWEB)

Murgatroyd, R A

1988-12-31

This document deals with the reliability of application of inspection procedures. A method to ensure that the inspection of defects thanks to fracture mechanics is reliable is described. The Systematic Human Error Reduction and Prediction Analysis (SHERPA) methodology is applied to every task performed by the inspector to estimate the possibility of error. It appears that it is essential that inspection procedures should be sufficiently rigorous to avoid substantial errors, and that the selection procedures and the training period for inspectors should be optimised. (TEC). 3 refs.

Reliability of application of inspection procedures

International Nuclear Information System (INIS)

Murgatroyd, R.A.

1988-01-01

This document deals with the reliability of application of inspection procedures. A method to ensure that the inspection of defects thanks to fracture mechanics is reliable is described. The Systematic Human Error Reduction and Prediction Analysis (SHERPA) methodology is applied to every task performed by the inspector to estimate the possibility of error. It appears that it is essential that inspection procedures should be sufficiently rigorous to avoid substantial errors, and that the selection procedures and the training period for inspectors should be optimised. (TEC)

The Children's Play Therapy Instrument (CPTI): Description, Development, and Reliability Studies

Science.gov (United States)

Kernberg, Paulina F.; Chazan, Saralea E.; Normandin, Lina

1998-01-01

The Children's Play Therapy Instrument (CPTI), its development, and reliability studies are described. The CPTI is a new instrument to examine a child's play activity in individual psychotherapy. Three independent raters used the CPTI to rate eight videotaped play therapy vignettes. Results were compared with the authors' consensual scores from a preliminary study. Generally good to excellent levels of interrater reliability were obtained for the independent raters on intraclass correlation coefficients for ordinal categories of the CPTI. Likewise, kappa levels were acceptable to excellent for nominal categories of the scale. The CPTI holds promise to become a reliable measure of play activity in child psychotherapy. Further research is needed to assess discriminant validity of the CPTI for use as a diagnostic tool and as a measure of process and outcome.(The Journal of Psychotherapy Practice and Research 1998; 7:196–207) PMID:9631341

A Reliability Generalization Study of the Marlowe-Crowne Social Desirability Scale.

Science.gov (United States)

Beretvas, S, Natasha; Meyers, Jason L.; Leite, Walter L.

2002-01-01

Conducted a reliability generalization study of the Marlowe-Crowne Social Desirability Scale (D. Crowne and D. Marlowe, 1960). Analysis of 93 studies show that the predicted score reliability for male adolescents was 0.53, and reliability for men's responses was lower than for women's. Discusses the need for further analysis of the scale. (SLD)

Reliability and relationship of radiographic measurements in hallux valgus.

Science.gov (United States)

Lee, Kyoung Min; Ahn, Soyeon; Chung, Chin Youb; Sung, Ki Hyuk; Park, Moon Seok

2012-09-01

Although various radiographic measurements have been developed and used for evaluating hallux valgus, not all are universally believed to be necessary and their relationships have not been clearly established. Determining which are related could provide some insight into which might be useful and which would not. We investigated the reliability of eight radiographic measurements used to evaluate hallux valgus, and determined which were correlated and which predicted the hallux valgus angle. We determined eight radiographic indices for 732 patients (mean age, 51 years; SD, 17 years; 107 males and 625 females) with hallux valgus: hallux valgus angle, intermetatarsal angle, hallux interphalangeal angle, distal metatarsal articular angle, proximal phalangeal articular angle, simplified metatarsus adductus angle, first metatarsal protrusion distance, and sesamoid rotation angle. Intraobserver and interobserver reliabilities of each radiographic measurement were analyzed on 36 feet from 36 randomly selected patients. Correlations among the radiographic measurements were analyzed. Radiographic measurements predicting hallux valgus angle were evaluated using multiple regression analysis. Hallux valgus angle had the highest reliability, whereas the distal metatarsal articular angle and simplified metatarsus adductus angle had the lowest. Distal metatarsal articular angle, intermetatarsal angle, and sesamoid rotation angle had the highest correlations with hallux valgus angle. Distal metatarsal articular angle correlated with sesamoid rotation angle. The intermetatarsal angle, interphalangeal angle, distal metatarsal articular angle, first metatarsal protrusion distance, sesamoid rotation angle, and metatarsus adductus angle predicted the hallux valgus angle. We suggest using hallux valgus angle, intermetatarsal angle, interphalangeal angle, sesamoid rotation angle, and first metatarsal protrusion distance considering their reliability and prediction of the deformity.

Validity and reliability of the NAB Naming Test.

Science.gov (United States)

Sachs, Bonnie C; Rush, Beth K; Pedraza, Otto

2016-05-01

Confrontation naming is commonly assessed in neuropsychological practice, but few standardized measures of naming exist and those that do are susceptible to the effects of education and culture. The Neuropsychological Assessment Battery (NAB) Naming Test is a 31-item measure used to assess confrontation naming. Despite adequate psychometric information provided by the test publisher, there has been limited independent validation of the test. In this study, we investigated the convergent and discriminant validity, internal consistency, and alternate forms reliability of the NAB Naming Test in a sample of adults (Form 1: n = 247, Form 2: n = 151) clinically referred for neuropsychological evaluation. Results indicate adequate-to-good internal consistency and alternate forms reliability. We also found strong convergent validity as demonstrated by relationships with other neurocognitive measures. We found preliminary evidence that the NAB Naming Test demonstrates a more pronounced ceiling effect than other commonly used measures of naming. To our knowledge, this represents the largest published independent validation study of the NAB Naming Test in a clinical sample. Our findings suggest that the NAB Naming Test demonstrates adequate validity and reliability and merits consideration in the test arsenal of clinical neuropsychologists.

Reliability of assessing the sensory perception of children with profound intellectual and multiple disabilities : a case study

NARCIS (Netherlands)

Vlaskamp, C.; Cuppen-Fonteine, H.

Background This study describes preliminary stages of developing a checklist to enable practitioners to determine the behavioural responses of children with profound intellectual and multiple disabilities to sensory stimuli. Reliability of currently used checklists is low, with a focus on the

Serum interleukin -8 is not a reliable marker for prediction of vesicoureteral reflux in children with febrile urinary tract infection

Directory of Open Access Journals (Sweden)

Abolfazl Mahyar

2015-12-01

Full Text Available Objective: In view of the side effects of voiding cystourethrography (VCUG, identification of noninvasive markers predicting the presence of vesicoureteral reflux (VUR is important. This study was conducted to determine the predictive value of serum interleukin-8 (IL-8 in diagnosis of VUR in children with first febrile urinary tract infection (UTI. Materials and Methods: Eighty children with first febrile UTI were divided into two groups, with and without VUR, based on the results of VCUG. The sensitivity, specificity, positive and negative predictive value positive and negative likelihood ratio, and accuracy of IL-8 for prediction of VUR were investigated. Results: Of the 80 children with febrile UTI, 30 (37.5% had VUR. There was no significant difference between the children with and without VUR and also between low and high-grade VUR groups in terms of serum concentration of IL-8 (P>0.05. Based on ROC curve, the sensitivity, specificity, likelihood ratio positive, and accuracy of serum IL-8 was lower than those of erythrocyte sedimentation rate and C-reactive protein. Multivariate logistic regression analysis showed significant positive correlation only between erythrocyte sedimentation rate and VUR. Conclusions: This study showed no significant difference between the children with and without VUR in terms of the serum concentration of IL-8. Therefore, it seems that serum IL-8 is not a reliable marker for prediction of VUR.

[Study of the relationship between human quality and reliability].

Science.gov (United States)

Long, S; Wang, C; Wang, L i; Yuan, J; Liu, H; Jiao, X

1997-02-01

To clarify the relationship between human quality and reliability, 1925 experiments in 20 subjects were carried out to study the relationship between disposition character, digital memory, graphic memory, multi-reaction time and education level and simulated aircraft operation. Meanwhile, effects of task difficulty and enviromental factor on human reliability were also studied. The results showed that human quality can be predicted and evaluated through experimental methods. The better the human quality, the higher the human reliability.

Development of a valid and reliable test to assess trauma radiograph interpretation performance

International Nuclear Information System (INIS)

Neep, M.J.; Steffens, T.; Riley, V.; Eastgate, P.; McPhail, S.M.

2017-01-01

Objectives: The purpose of this investigation was to develop and examine the preliminary validity and reliability among radiographers of a test to assess trauma radiograph interpretation performance suitable for use among health professionals. Methods: Stage 1 examined 14,159 consecutive appendicular and axial examinations from a hospital emergency department over a 12 month period to quantify a typical anatomical region case-mix of trauma radiographs. A sample of radiographic cases representative of affected anatomical regions was then developed into the Image Interpretation Test (IIT). Stage 2 involved prospective investigations of the IIT's reliability (inter-rater, intra-rater, internal consistency) and validity (concurrent) among 41 radiographers. Results: The IIT included 60 cases. The median (interquartile range) clinical experience of participants was 5 (2–10) years. Case scores were internally consistent (Cronbach's alpha = 0.90). Favourable inter-rater reliability (kappa > 0.70 for 58/60 cases, Intra-class correlation coefficient (ICC) > 0.99 for total score) and intra-rater reliability (kappa > 0.90 for 60/60 cases, ICC > 0.99 for total score) was observed. There was a positive association between radiographers' confidence in image interpretation and IIT score (coefficient = 1.52, r-squared = 0.60, p < 0.001). Conclusions: The IIT developed during this investigation included a selection of radiographic cases consistent with anatomical regions represented in an adult trauma case-mix. This study has also provided foundational preliminary evidence to support the reliability and validity of the IIT among radiographers. The findings suggest that it is possible to assess image interpretation performance of adult trauma radiographs with this test. - Highlights: • Development of an Image Interpretation Test (IIT). • Cases consistent with anatomical regions represented in a typical adult trauma case-mix. • Development of a

Applications of majorization and Schur functions in reliability and life testing

International Nuclear Information System (INIS)

Proschan, F.

1975-01-01

This is an expository paper presenting basic definitions and properties of majorization and Schur functions, and displaying a variety of applications of these concepts in reliability prediction and modelling, and in reliability inference and life testing

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.

Designing reliable supply chain network with disruption risk

Directory of Open Access Journals (Sweden)

Ali Bozorgi Amiri

2013-01-01

Full Text Available Although supply chains disruptions rarely occur, their negative effects are prolonged and severe. In this paper, we propose a reliable capacitated supply chain network design (RSCND model by considering random disruptions in both distribution centers and suppliers. The proposed model determines the optimal location of distribution centers (DC with the highest reliability, the best plan to assign customers to opened DCs and assigns opened DCs to suitable suppliers with lowest transportation cost. In this study, random disruption occurs at the location, capacity of the distribution centers (DCs and suppliers. It is assumed that a disrupted DC and a disrupted supplier may lose a portion of their capacities, and the rest of the disrupted DC's demand can be supplied by other DCs. In addition, we consider shortage in DCs, which can occur in either normal or disruption conditions and DCs, can support each other in such circumstances. Unlike other studies in the extent of literature, we use new approach to model the reliability of DCs; we consider a range of reliability instead of using binary variables. In order to solve the proposed model for real-world instances, a Non-dominated Sorting Genetic Algorithm-II (NSGA-II is applied. Preliminary results of testing the proposed model of this paper on several problems with different sizes provide seem to be promising.

Reliability Engineering Analysis of ATLAS Data Reprocessing Campaigns

CERN Document Server

Vaniachine, A; The ATLAS collaboration; Karpenko, D

2013-01-01

During three years of LHC data taking, the ATLAS collaboration completed three petascale data reprocessing campaigns on the Grid, with up to 2 PB of data being reprocessed every year. In reprocessing on the Grid, failures can occur for a variety of reasons, while Grid heterogeneity makes failures hard to diagnose and repair quickly. As a result, Big Data processing on the Grid must tolerate a continuous stream of failures, errors and faults. While ATLAS fault-tolerance mechanisms improve the reliability of Big Data processing in the Grid, their benefits come at costs and result in delays making the performance prediction difficult. Reliability Engineering provides a framework for fundamental understanding of the Big Data processing on the Grid, which is not a desirable enhancement but a necessary requirement. In ATLAS, cost monitoring and performance prediction became critical for the success of the reprocessing campaigns conducted in preparation for the major physics conferences. In addition, our Reliability...

Reliability Engineering Analysis of ATLAS Data Reprocessing Campaigns

CERN Document Server

Vaniachine, A; The ATLAS collaboration; Karpenko, D

2014-01-01

During three years of LHC data taking, the ATLAS collaboration completed three petascale data reprocessing campaigns on the Grid, with up to 2 PB of data being reprocessed every year. In reprocessing on the Grid, failures can occur for a variety of reasons, while Grid heterogeneity makes failures hard to diagnose and repair quickly. As a result, Big Data processing on the Grid must tolerate a continuous stream of failures, errors and faults. While ATLAS fault-tolerance mechanisms improve the reliability of Big Data processing in the Grid, their benefits come at costs and result in delays making the performance prediction difficult. Reliability Engineering provides a framework for fundamental understanding of the Big Data processing on the Grid, which is not a desirable enhancement but a necessary requirement. In ATLAS, cost monitoring and performance prediction became critical for the success of the reprocessing campaigns conducted in preparation for the major physics conferences. In addition, our Reliability...

Evaluation for nuclear safety-critical software reliability of DCS

International Nuclear Information System (INIS)

Liu Ying

2015-01-01

With the development of control and information technology at NPPs, software reliability is important because software failure is usually considered as one form of common cause failures in Digital I and C Systems (DCS). The reliability analysis of DCS, particularly qualitative and quantitative evaluation on the nuclear safety-critical software reliability belongs to a great challenge. To solve this problem, not only comprehensive evaluation model and stage evaluation models are built in this paper, but also prediction and sensibility analysis are given to the models. It can make besement for evaluating the reliability and safety of DCS. (author)

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.

Cognitive Task Analysis of Business Jet Pilots' Weather Flying Behaviors: Preliminary Results

Science.gov (United States)

Latorella, Kara; Pliske, Rebecca; Hutton, Robert; Chrenka, Jason

2001-01-01

This report presents preliminary findings from a cognitive task analysis (CTA) of business aviation piloting. Results describe challenging weather-related aviation decisions and the information and cues used to support these decisions. Further, these results demonstrate the role of expertise in business aviation decision-making in weather flying, and how weather information is acquired and assessed for reliability. The challenging weather scenarios and novice errors identified in the results provide the basis for experimental scenarios and dependent measures to be used in future flight simulation evaluations of candidate aviation weather information systems. Finally, we analyzed these preliminary results to recommend design and training interventions to improve business aviation decision-making with weather information. The primary objective of this report is to present these preliminary findings and to document the extended CTA methodology used to elicit and represent expert business aviator decision-making with weather information. These preliminary findings will be augmented with results from additional subjects using this methodology. A summary of the complete results, absent the detailed treatment of methodology provided in this report, will be documented in a separate publication.

A Method of Nuclear Software Reliability Estimation

International Nuclear Information System (INIS)

Park, Gee Yong; Eom, Heung Seop; Cheon, Se Woo; Jang, Seung Cheol

2011-01-01

A method on estimating software reliability for nuclear safety software is proposed. This method is based on the software reliability growth model (SRGM) where the behavior of software failure is assumed to follow the non-homogeneous Poisson process. Several modeling schemes are presented in order to estimate and predict more precisely the number of software defects based on a few of software failure data. The Bayesian statistical inference is employed to estimate the model parameters by incorporating the software test cases into the model. It is identified that this method is capable of accurately estimating the remaining number of software defects which are on-demand type directly affecting safety trip functions. The software reliability can be estimated from a model equation and one method of obtaining the software reliability is proposed

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)

A text-based data mining and toxicity prediction modeling system for a clinical decision support in radiation oncology: A preliminary study

Science.gov (United States)

Kim, Kwang Hyeon; Lee, Suk; Shim, Jang Bo; Chang, Kyung Hwan; Yang, Dae Sik; Yoon, Won Sup; Park, Young Je; Kim, Chul Yong; Cao, Yuan Jie

2017-08-01

The aim of this study is an integrated research for text-based data mining and toxicity prediction modeling system for clinical decision support system based on big data in radiation oncology as a preliminary research. The structured and unstructured data were prepared by treatment plans and the unstructured data were extracted by dose-volume data image pattern recognition of prostate cancer for research articles crawling through the internet. We modeled an artificial neural network to build a predictor model system for toxicity prediction of organs at risk. We used a text-based data mining approach to build the artificial neural network model for bladder and rectum complication predictions. The pattern recognition method was used to mine the unstructured toxicity data for dose-volume at the detection accuracy of 97.9%. The confusion matrix and training model of the neural network were achieved with 50 modeled plans (n = 50) for validation. The toxicity level was analyzed and the risk factors for 25% bladder, 50% bladder, 20% rectum, and 50% rectum were calculated by the artificial neural network algorithm. As a result, 32 plans could cause complication but 18 plans were designed as non-complication among 50 modeled plans. We integrated data mining and a toxicity modeling method for toxicity prediction using prostate cancer cases. It is shown that a preprocessing analysis using text-based data mining and prediction modeling can be expanded to personalized patient treatment decision support based on big data.

Reliability in the design phase

International Nuclear Information System (INIS)

Siahpush, A.S.; Hills, S.W.; Pham, H.; Majumdar, D.

1991-12-01

A study was performed to determine the common methods and tools that are available to calculated or predict a system's reliability. A literature review and software survey are included. The desired product of this developmental work is a tool for the system designer to use in the early design phase so that the final design will achieve the desired system reliability without lengthy testing and rework. Three computer programs were written which provide the first attempt at fulfilling this need. The programs are described and a case study is presented for each one. This is a continuing effort which will be furthered in FY-1992. 10 refs

The reliability of financial information of charitable organizations: an exploratory study based on the Benford’s Law

Directory of Open Access Journals (Sweden)

Marco Antonio Figueiredo Milani Filho

2013-08-01

Full Text Available Benford's Law (BL is a logarithmic distribution which is useful to detect abnormal patterns of digits in number sets. It is often used as a primary data auditing method for detecting traces of errors, illegal practices or undesired occurrences, such as fraud and earning management. In this descriptive study, I analyzed the financial information (revenue and expenditure of the registered charitable hospitals located in Ontario and Quebec, which have the majority (71.4% of these organizations within Canada. The aim of this study was to verify the reliability of the financial data of the respective hospitals, using the probability distribution predicted by Benford’s Law as a proxy of reliability. The sample was composed by 1,334 observations related to 339 entities operating in the tax year 2009 and 328 entities in 2010, gathered from the Canada Revenue Agency’s database. To analyze the discrepancies between the actual and expected frequencies of the significant-digit, two statistics were calculated: Z-test and Pearson’s chi-square test. The results show that, with a confidence level of 95%, the data set of the organizations located in Ontario and Quebec have similar distribution to the BL, suggesting that, in a preliminary analysis, their financial data are free from bias.

Proof tests on reliability

International Nuclear Information System (INIS)

Mishima, Yoshitsugu

1983-01-01

In order to obtain public understanding on nuclear power plants, tests should be carried out to prove the reliability and safety of present LWR plants. For example, the aseismicity of nuclear power plants must be verified by using a large scale earthquake simulator. Reliability test began in fiscal 1975, and the proof tests on steam generators and on PWR support and flexure pins against stress corrosion cracking have already been completed, and the results have been internationally highly appreciated. The capacity factor of the nuclear power plant operation in Japan rose to 80% in the summer of 1983, and considering the period of regular inspection, it means the operation of almost full capacity. Japanese LWR technology has now risen to the top place in the world after having overcome the defects. The significance of the reliability test is to secure the functioning till the age limit is reached, to confirm the correct forecast of deteriorating process, to confirm the effectiveness of the remedy to defects and to confirm the accuracy of predicting the behavior of facilities. The reliability of nuclear valves, fuel assemblies, the heat affected zones in welding, reactor cooling pumps and electric instruments has been tested or is being tested. (Kako, I.)

The importance of reliability to the SunShot Initiative (Presentation Recording)

Science.gov (United States)

Jones-Albertus, Rebecca

2015-09-01

The U.S. Department of Energy's SunShot Initiative was launched in 2011 to make subsidy-free solar electricity cost competitive with conventional energy sources by the end of the decade. Research in reliability can play a major role in realizing the SunShot goal of 0.06/kWh. By improving photovoltaic module lifetime and reducing degradation rates, a system's lifetime energy output is increased. Increasing confidence in photovoltaic performance prediction can lower perceived investment risk and thus the cost of capital. Accordingly, in 2015, SunShot expects to award more than $40 million through its SunShot National Laboratory Multiyear Partnership (SuNLaMP) and Physics of Reliability: Evaluating Design Insights for Component Technologies in Solar (PREDICTS) 2 funding programs, for research into reliability topics such as determining acceleration factors, modeling degradation rates and failure mechanisms, improving predictive performance models, and developing new test methods and instrumentation.

Guidelines for the regulatory review of the human reliability analysis in PSAs

International Nuclear Information System (INIS)

Reer, Bernhard; Dang, V.N.; Hirschberg, Stefan; Meyer, Patrick

2000-01-01

In the review guidelines recently developed for the Swiss Federal Nuclear Inspectorate, the Human Reliability Analysis (HRA) is reviewed in two stages. The preliminary review is aimed at identifying major shortcomings and potential issues to be examined in the detailed review. The detailed review comprehensively addresses the overall adequacy and transparency of the HRA. For the two review stages, 97 indicators are defined in terms of questions focusing on verifiable features of the methodology, implementation and results. The guidelines provide steps for information gathering and present examples of acceptable practices as well as of potential deficiencies. Both review stages may result in requests for clarification, additional documentation or analyses. The first applications of the guidelines consist of the preliminary reviews of two HRAs. (author)

Seasonal climate prediction for North Eurasia

International Nuclear Information System (INIS)

Kryjov, Vladimir N

2012-01-01

An overview of the current status of the operational seasonal climate prediction for North Eurasia is presented. It is shown that the performance of existing climate models is rather poor in seasonal prediction for North Eurasia. Multi-model ensemble forecasts are more reliable than single-model ones; however, for North Eurasia they tend to be close to climatological ones. Application of downscaling methods may improve predictions for some locations (or regions). However, general improvement of the reliability of seasonal forecasts for North Eurasia requires improvement of the climate prediction models. (letter)

Further HTGR core support structure reliability studies. Interim report No. 1

International Nuclear Information System (INIS)

Platus, D.L.

1976-01-01

Results of a continuing effort to investigate high temperature gas cooled reactor (HTGR) core support structure reliability are described. Graphite material and core support structure component physical, mechanical and strength properties required for the reliability analysis are identified. Also described are experimental and associated analytical techniques for determining the required properties, a procedure for determining number of tests required, properties that might be monitored by special surveillance of the core support structure to improve reliability predictions, and recommendations for further studies. Emphasis in the study is directed towards developing a basic understanding of graphite failure and strength degradation mechanisms; and validating analytical methods for predicting strength and strength degradation from basic material properties

Preliminary analysis of a 1:4 scale prestressed concrete containment vessel model

International Nuclear Information System (INIS)

Dameron, R.A.; Rashid, Y.R.; Luk, V.K.; Hessheimer, M.F.

1997-01-01

Sandia National Laboratories is conducting a research program to investigate the integrity of nuclear containment structures. As part of the program Sandia will construct an instrumented 1:4 scale model of a prestressed concrete containment vessel (PCCV) for pressurized water reactors (PWR), which will be pressure tested up to its ultimate capacity. One of the key program objectives is to develop validated methods to predict the structural performance of containment vessels when subjected to beyond design basis loadings. Analytical prediction of structural performance requires a stepwise, systematic approach that addresses all potential failure modes. The analysis effort includes two and three-dimensional nonlinear finite element analyses of the PCCV test model to evaluate its structural performance under very high internal pressurization. Such analyses have been performed using the nonlinear concrete constitutive model, ANACAP-U, in conjunction with the ABAQUS general purpose finite element code. The analysis effort is carried out in three phases: preliminary analysis; pretest prediction; and post-test data interpretation and analysis evaluation. The preliminary analysis phase serves to provide instrumentation support and identify candidate failure modes. The associated tasks include the preliminary prediction of failure pressure and probable failure locations and the development of models to be used in the detailed failure analyses. This paper describes the modeling approaches and some of the results obtained in the first phase of the analysis effort

Influences on the Test-Retest Reliability of Functional Connectivity MRI and its Relationship with Behavioral Utility.

Science.gov (United States)

Noble, Stephanie; Spann, Marisa N; Tokoglu, Fuyuze; Shen, Xilin; Constable, R Todd; Scheinost, Dustin

2017-11-01

Best practices are currently being developed for the acquisition and processing of resting-state magnetic resonance imaging data used to estimate brain functional organization-or "functional connectivity." Standards have been proposed based on test-retest reliability, but open questions remain. These include how amount of data per subject influences whole-brain reliability, the influence of increasing runs versus sessions, the spatial distribution of reliability, the reliability of multivariate methods, and, crucially, how reliability maps onto prediction of behavior. We collected a dataset of 12 extensively sampled individuals (144 min data each across 2 identically configured scanners) to assess test-retest reliability of whole-brain connectivity within the generalizability theory framework. We used Human Connectome Project data to replicate these analyses and relate reliability to behavioral prediction. Overall, the historical 5-min scan produced poor reliability averaged across connections. Increasing the number of sessions was more beneficial than increasing runs. Reliability was lowest for subcortical connections and highest for within-network cortical connections. Multivariate reliability was greater than univariate. Finally, reliability could not be used to improve prediction; these findings are among the first to underscore this distinction for functional connectivity. A comprehensive understanding of test-retest reliability, including its limitations, supports the development of best practices in the field. © The Author 2017. Published by Oxford University Press.

A study on a reliability assessment methodology for the VHTR safety systems

International Nuclear Information System (INIS)

Lee, Hyung Sok

2012-02-01

The passive safety system of a 300MWt VHTR (Very High Temperature Reactor)which has attracted worldwide attention recently is actively considered for designing the improvement in the safety of the next generation nuclear power plant. The passive system functionality does not rely on an external source of the electrical support system,but on an intelligent use of the natural phenomena, such as convection, conduction, radiation, and gravity. It is not easy to evaluate quantitatively the reliability of the passive safety for the risk analysis considering the existing active system failure since the classical reliability assessment method could not be applicable. Therefore a new reliability methodology needs to be developed and applied for evaluating the reliability of the conceptual designed VHTR in this study. The preliminary evaluation and conceptualization are performed using the concept of the load and capacity theory related to the reliability physics model. The method of response surface method (RSM) is also utilized for evaluating the maximum temperature of nuclear fuel in this study. The significant variables and their correlation are considered for utilizing the GAMMA+ code. The proposed method might contribute to designing the new passive system of the VHTR

Rater reliability and construct validity of a mobile application for posture analysis.

Science.gov (United States)

Szucs, Kimberly A; Brown, Elena V Donoso

2018-01-01

[Purpose] Measurement of posture is important for those with a clinical diagnosis as well as researchers aiming to understand the impact of faulty postures on the development of musculoskeletal disorders. A reliable, cost-effective and low tech posture measure may be beneficial for research and clinical applications. The purpose of this study was to determine rater reliability and construct validity of a posture screening mobile application in healthy young adults. [Subjects and Methods] Pictures of subjects were taken in three standing positions. Two raters independently digitized the static standing posture image twice. The app calculated posture variables, including sagittal and coronal plane translations and angulations. Intra- and inter-rater reliability were calculated using the appropriate ICC models for complete agreement. Construct validity was determined through comparison of known groups using repeated measures ANOVA. [Results] Intra-rater reliability ranged from 0.71 to 0.99. Inter-rater reliability was good to excellent for all translations. ICCs were stronger for translations versus angulations. The construct validity analysis found that the app was able to detect the change in the four variables selected. [Conclusion] The posture mobile application has demonstrated strong rater reliability and preliminary evidence of construct validity. This application may have utility in clinical and research settings.

Reliability Analysis of Safety Grade PLC(POSAFE-Q) for Nuclear Power Plants

International Nuclear Information System (INIS)

Kim, J. Y.; Lyou, J.; Lee, D. Y.; Choi, J. G.; Park, W. M.

2006-01-01

The Part Count Method of the military standard MILHDK- 217F has been used for the reliability prediction of the nuclear field. This handbook determines the Programmable Logic Controller (PLC) failure rate by summing the failure rates of the individual component included in the PLC. Normally it is easily predictable that the components added for the fault detection improve the reliability of the PLC. But the application of this handbook is estimated with poor reliability because of the increased component number for the fault detection. To compensate this discrepancy, the quantitative reliability analysis method is suggested using the functional separation model in this paper. And it is applied to the Reactor Protection System (RPS) being developed in Korea to identify any design weak points from a safety point of view

Reliability and Validity of the Work and Well-Being Inventory (WBI) for Employees.

Science.gov (United States)

Vendrig, A A; Schaafsma, F G

2018-06-01

Purpose The purpose of this study is to measure the psychometric properties of the Work and Wellbeing Inventory (WBI) (in Dutch: VAR-2), a screening tool that is used within occupational health care and rehabilitation. Our research question focused on the reliability and validity of this inventory. Methods Over the years seven different samples of workers, patients and sick listed workers varying in size between 89 and 912 participants (total: 2514), were used to measure the test-retest reliability, the internal consistency, the construct and concurrent validity, and the criterion and predictive validity. Results The 13 scales displayed good internal consistency and test-retest reliability. The constructive validity of the WBI could clearly be demonstrated in both patients and healthy workers. Confirmative factor analyses revealed a CFI >.90 for all scales. The depression scale predicted future work absenteeism (>6 weeks) because of a common mental disorder in healthy workers. The job strain scale and the illness behavior scale predicted long term absenteeism (>3 months) in workers with short-term absenteeism. The illness behavior scale moderately predicted return to work in rehab patients attending an intensive multidisciplinary program. Conclusions The WBI is a valid and reliable tool for occupational health practitioners to screen for risk factors for prolonged or future sickness absence. With this tool they will have reliable indications for further advice and interventions to restore the work ability.

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.

Prediction on fracture risk of femur with Osteogenesis Imperfecta using finite element models: Preliminary study

Science.gov (United States)

Wanna, S. B. C.; Basaruddin, K. S.; Mat Som, M. H.; Mohamad Hashim, M. S.; Daud, R.; Majid, M. S. Abdul; Sulaiman, A. R.

2017-10-01

Osteogenesis imperfecta (OI) is a genetic disease which affecting the bone geometry. In a severe case, this disease can cause death to patients. The main issue of this disease is the prediction on bone fracture by the orthopaedic surgeons. The resistance of the bone to withstand the force before the bones fracture often become the main concern. Therefore, the objective of the present preliminary study was to investigate the fracture risk associated with OI bone, particularly in femur, when subjected to the self-weight. Finite element (FEA) was employed to reconstruct the OI bone model and analyse the mechanical stress response of femur before it fractures. Ten deformed models with different severity of OI bones were developed and the force that represents patient self-weight was applied to the reconstructed models in static analysis. Stress and fracture risk were observed and analysed throughout the simulation. None of the deformed model were observed experienced fracture. The fracture risk increased with increased severity of the deformed bone. The results showed that all deformed femur models were able to bear the force without experienced fracture when subjected to only the self-weight.

Equipment Reliability Program in NPP Krsko

International Nuclear Information System (INIS)

Skaler, F.; Djetelic, N.

2006-01-01

Operation that is safe, reliable, effective and acceptable to public is the common message in a mission statement of commercial nuclear power plants (NPPs). To fulfill these goals, nuclear industry, among other areas, has to focus on: 1 Human Performance (HU) and 2 Equipment Reliability (EQ). The performance objective of HU is as follows: The behaviors of all personnel result in safe and reliable station operation. While unwanted human behaviors in operations mostly result directly in the event, the behavior flaws either in the area of maintenance or engineering usually cause decreased equipment reliability. Unsatisfied Human performance leads even the best designed power plants into significant operating events, which can be found as well-known examples in nuclear industry. Equipment reliability is today recognized as the key to success. While the human performance at most NPPs has been improving since the start of WANO / INPO / IAEA evaluations, the open energy market has forced the nuclear plants to reduce production costs and operate more reliably and effectively. The balance between these two (opposite) goals has made equipment reliability even more important for safe, reliable and efficient production. Insisting on on-line operation by ignoring some principles of safety could nowadays in a well-developed safety culture and human performance environment exceed the cost of electricity losses. In last decade the leading USA nuclear companies put a lot of effort to improve equipment reliability primarily based on INPO Equipment Reliability Program AP-913 at their NPP stations. The Equipment Reliability Program is the key program not only for safe and reliable operation, but also for the Life Cycle Management and Aging Management on the way to the nuclear power plant life extension. The purpose of Equipment Reliability process is to identify, organize, integrate and coordinate equipment reliability activities (preventive and predictive maintenance, maintenance

Reliability engineering analysis of ATLAS data reprocessing campaigns

International Nuclear Information System (INIS)

Vaniachine, A; Golubkov, D; Karpenko, D

2014-01-01

During three years of LHC data taking, the ATLAS collaboration completed three petascale data reprocessing campaigns on the Grid, with up to 2 PB of data being reprocessed every year. In reprocessing on the Grid, failures can occur for a variety of reasons, while Grid heterogeneity makes failures hard to diagnose and repair quickly. As a result, Big Data processing on the Grid must tolerate a continuous stream of failures, errors and faults. While ATLAS fault-tolerance mechanisms improve the reliability of Big Data processing in the Grid, their benefits come at costs and result in delays making the performance prediction difficult. Reliability Engineering provides a framework for fundamental understanding of the Big Data processing on the Grid, which is not a desirable enhancement but a necessary requirement. In ATLAS, cost monitoring and performance prediction became critical for the success of the reprocessing campaigns conducted in preparation for the major physics conferences. In addition, our Reliability Engineering approach supported continuous improvements in data reprocessing throughput during LHC data taking. The throughput doubled in 2011 vs. 2010 reprocessing, then quadrupled in 2012 vs. 2011 reprocessing. We present the Reliability Engineering analysis of ATLAS data reprocessing campaigns providing the foundation needed to scale up the Big Data processing technologies beyond the petascale.

Reducing Reliability Uncertainties for Marine Renewable Energy

Directory of Open Access Journals (Sweden)

Sam D. Weller

2015-11-01

Full Text Available Technology Readiness Levels (TRLs are a widely used metric of technology maturity and risk for marine renewable energy (MRE devices. To-date, a large number of device concepts have been proposed which have reached the early validation stages of development (TRLs 1–3. Only a handful of mature designs have attained pre-commercial development status following prototype sea trials (TRLs 7–8. In order to navigate through the aptly named “valley of death” (TRLs 4–6 towards commercial realisation, it is necessary for new technologies to be de-risked in terms of component durability and reliability. In this paper the scope of the reliability assessment module of the DTOcean Design Tool is outlined including aspects of Tool integration, data provision and how prediction uncertainties are accounted for. In addition, two case studies are reported of mooring component fatigue testing providing insight into long-term component use and system design for MRE devices. The case studies are used to highlight how test data could be utilised to improve the prediction capabilities of statistical reliability assessment approaches, such as the bottom–up statistical method.

Using a situational judgement test for selection into dental core training: a preliminary analysis.

Science.gov (United States)

Rowett, E; Patterson, F; Cousans, F; Elley, K

2017-05-12

Objective and setting This paper describes the evaluation of a pilot situational judgement test (SJT) for selection into UK Dental Core Training (DCT). The SJT's psychometric properties, group differences based on gender and ethnicity, and candidate reactions were assessed.Methods The SJT targets four non-academic attributes important for success in DCT. Data were collected alongside live selection processes from five Health Education England local teams in the UK (N = 386). Candidates completed the pilot SJT and an evaluation questionnaire to examine their reactions to the test.Results SJT scores were relatively normally distributed and showed acceptable levels of internal reliability (α = 0.68). Difficulty level and partial correlations between scenarios and SJT total score were in the expected ranges (64.61% to 90.03% and r = 0.06 to 0.41, respectively). No group differences were found for gender, and group differences between White and BME candidates were minimal. Most candidates perceived the SJT as relevant to the target role, appropriate and fair.Conclusions This study demonstrated the potential suitability of an SJT for use in DCT selection. Future research should replicate these preliminary findings in other cohorts, and assess the predictive validity of the SJT for predicting key training and practice-based outcomes.

Procalcitonin for the early prediction of renal parenchymal involvement in children with UTI: preliminary results.

Science.gov (United States)

Kotoula, Aggeliki; Gardikis, Stefanos; Tsalkidis, Aggelos; Mantadakis, Elpis; Zissimopoulos, Athanassios; Kambouri, Katerina; Deftereos, Savvas; Tripsianis, Gregorios; Manolas, Konstantinos; Chatzimichael, Athanassios; Vaos, George

2009-01-01

In order to establish the most reliable marker for distinguishing urinary tract infections (UTI) with and without renal parenchymal involvement (RPI), we recorded the clinical features and admission leukocyte count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum procalcitonin (PCT) in 57 children (including 43 girls) aged 2-108 months admitted with a first episode of UTI. RPI was evaluated by Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy within 7 days of admission. To establish cut-off points for ESR, CRP, and PCT, we used receiver operating characteristics curves and compared the area under the curve for ESR, CRP, and PCT. Twenty-seven children were diagnosed as having RPI based on positive renal scintigraphy. A body temperature of >38 degrees C, a history of diarrhea, and poor oral intake were more common in patients with RPI. ESR, CRP, and PCT, but not leukocyte count, were significantly higher in patients with RPI (P UTI than ESR and CRP. Using a cut-off value of 0.85 ng/ml, PCT had the best performance, with sensitivity, specificity, and positive and negative predictive values of 89%, 97%, 96%, and 91% respectively. Serum PCT is a better marker than ESR, CRP, and leukocyte count for the early prediction of RPI in children with a first episode of UTI.

Reliability Characteristics of Power Plants

Directory of Open Access Journals (Sweden)

Zbynek Martinek

2017-01-01

Full Text Available This paper describes the phenomenon of reliability of power plants. It gives an explanation of the terms connected with this topic as their proper understanding is important for understanding the relations and equations which model the possible real situations. The reliability phenomenon is analysed using both the exponential distribution and the Weibull distribution. The results of our analysis are specific equations giving information about the characteristics of the power plants, the mean time of operations and the probability of failure-free operation. Equations solved for the Weibull distribution respect the failures as well as the actual operating hours. Thanks to our results, we are able to create a model of dynamic reliability for prediction of future states. It can be useful for improving the current situation of the unit as well as for creating the optimal plan of maintenance and thus have an impact on the overall economics of the operation of these power plants.

Reliability Evaluation on Creep Life Prediction of Alloy 617 for a Very High Temperature Reactor

International Nuclear Information System (INIS)

Kim, Woo-Gon; Hong, Sung-Deok; Kim, Yong-Wan; Park, Jae-Young; Kim, Seon-Jin

2012-01-01

This paper evaluates the reliability of creep rupture life under service conditions of Alloy 617, which is considered as one of the candidate materials for use in a very high temperature reactor (VHTR) system. A Z-parameter, which represents the deviation of creep rupture data from the master curve, was used for the reliability analysis of the creep rupture data of Alloy 617. A Service-condition Creep Rupture Interference (SCRI) model, which can consider both the scattering of the creep rupture data and the fluctuations of temperature and stress under any service conditions, was also used for evaluating the reliability of creep rupture life. The statistical analysis showed that the scattering of creep rupture data based on Z-parameter was supported by normal distribution. The values of reliability decreased rapidly with increasing amplitudes of temperature and stress fluctuations. The results established that the reliability decreased with an increasing service time.

NASA Applications and Lessons Learned in Reliability Engineering

Science.gov (United States)

Safie, Fayssal M.; Fuller, Raymond P.

2011-01-01

Since the Shuttle Challenger accident in 1986, communities across NASA have been developing and extensively using quantitative reliability and risk assessment methods in their decision making process. This paper discusses several reliability engineering applications that NASA has used over the year to support the design, development, and operation of critical space flight hardware. Specifically, the paper discusses several reliability engineering applications used by NASA in areas such as risk management, inspection policies, components upgrades, reliability growth, integrated failure analysis, and physics based probabilistic engineering analysis. In each of these areas, the paper provides a brief discussion of a case study to demonstrate the value added and the criticality of reliability engineering in supporting NASA project and program decisions to fly safely. Examples of these case studies discussed are reliability based life limit extension of Shuttle Space Main Engine (SSME) hardware, Reliability based inspection policies for Auxiliary Power Unit (APU) turbine disc, probabilistic structural engineering analysis for reliability prediction of the SSME alternate turbo-pump development, impact of ET foam reliability on the Space Shuttle System risk, and reliability based Space Shuttle upgrade for safety. Special attention is given in this paper to the physics based probabilistic engineering analysis applications and their critical role in evaluating the reliability of NASA development hardware including their potential use in a research and technology development environment.

Reliability of the Dissociative Trance Disorder Interview Schedule: A preliminary report.

Science.gov (United States)

Ross, Colin A; Somer, Eli; Goode, Caitlin

2018-01-01

One hundred inpatients in a hospital-based Trauma Program in the USA were interviewed with the Dissociative Trance Disorder Interview Schedule (DTDIS). There were no significant differences for the DTDIS total score or any of the subscale scores on test-retest: all t-values comparing the two administrations of the DTDIS were below 0.7, and all p-values were above 0.5. Cronbach's alpha for the US sample was 0.966 and for the Israeli sample it was 0.971. The findings indicate that the DTDIS has good reliability and may be suitable for use in cross-cultural research; however, the results require replication by independent researchers in a variety of cultures and languages, and in both clinical and nonclinical samples.

Test-retest reliability of the Middlesex Assessment of Mental State (MEAMS): a preliminary investigation in people with probable dementia.

Science.gov (United States)

Powell, T; Brooker, D J; Papadopolous, A

1993-05-01

Relative and absolute test-retest reliability of the MEAMS was examined in 12 subjects with probable dementia and 12 matched controls. Relative reliability was good. Measures of absolute reliability showed scores changing by up to 3 points over an interval of a week. A version effect was found to be in evidence.

Flood design recipes vs. reality: can predictions for ungauged basins be trusted?

Science.gov (United States)

Efstratiadis, A.; Koussis, A. D.; Koutsoyiannis, D.; Mamassis, N.

2014-06-01

Despite the great scientific and technological advances in flood hydrology, everyday engineering practices still follow simplistic approaches that are easy to formally implement in ungauged areas. In general, these "recipes" have been developed many decades ago, based on field data from typically few experimental catchments. However, many of them have been neither updated nor validated across all hydroclimatic and geomorphological conditions. This has an obvious impact on the quality and reliability of hydrological studies, and, consequently, on the safety and cost of the related flood protection works. Preliminary results, based on historical flood data from Cyprus and Greece, indicate that a substantial revision of many aspects of flood engineering procedures is required, including the regionalization formulas as well as the modelling concepts themselves. In order to provide a consistent design framework and to ensure realistic predictions of the flood risk (a key issue of the 2007/60/EU Directive) in ungauged basins, it is necessary to rethink the current engineering practices. In this vein, the collection of reliable hydrological data would be essential for re-evaluating the existing "recipes", taking into account local peculiarities, and for updating the modelling methodologies as needed.

Web server's reliability improvements using recurrent neural networks

DEFF Research Database (Denmark)

Madsen, Henrik; Albu, Rǎzvan-Daniel; Felea, Ioan

2012-01-01

In this paper we describe an interesting approach to error prediction illustrated by experimental results. The application consists of monitoring the activity for the web servers in order to collect the specific data. Predicting an error with severe consequences for the performance of a server (t...... usage, network usage and memory usage. We collect different data sets from monitoring the web server's activity and for each one we predict the server's reliability with the proposed recurrent neural network. © 2012 Taylor & Francis Group...

The Anaclitic-Introjective Depression Assessment: Development and preliminary validity of an observer-rated measure.

Science.gov (United States)

Rost, Felicitas; Luyten, Patrick; Fonagy, Peter

2018-03-01

The two-configurations model developed by Blatt and colleagues offers a comprehensive conceptual and empirical framework for understanding depression. This model suggests that depressed patients struggle, at different developmental levels, with issues related to dependency (anaclitic issues) or self-definition (introjective issues), or a combination of both. This paper reports three studies on the development and preliminary validation of the Anaclitic-Introjective Depression Assessment, an observer-rated assessment tool of impairments in relatedness and self-definition in clinical depression based on the item pool of the Shedler-Westen Assessment Procedure. Study 1 describes the development of the measure using expert consensus rating and Q-methodology. Studies 2 and 3 report the assessment of its psychometric properties, preliminary reliability, and validity in a sample of 128 patients diagnosed with treatment-resistant depression. Four naturally occurring clusters of depressed patients were identified using Q-factor analysis, which, overall, showed meaningful and theoretically expected relationships with anaclitic/introjective prototypes as formulated by experts, as well as with clinical, social, occupational, global, and relational functioning. Taken together, findings reported in this paper provide preliminary evidence for the reliability and validity of the Anaclitic-Introjective Depression Assessment, an observer-rated measure that allows the detection of important nuanced differentiations between and within anaclitic and introjective depression. Copyright © 2017 John Wiley & Sons, Ltd.

An integrated approach to estimate storage reliability with initial failures based on E-Bayesian estimates

International Nuclear Information System (INIS)

Zhang, Yongjin; Zhao, Ming; Zhang, Shitao; Wang, Jiamei; Zhang, Yanjun

2017-01-01

Storage reliability that measures the ability of products in a dormant state to keep their required functions is studied in this paper. For certain types of products, Storage reliability may not always be 100% at the beginning of storage, unlike the operational reliability, which exist possible initial failures that are normally neglected in the models of storage reliability. In this paper, a new integrated technique, the non-parametric measure based on the E-Bayesian estimates of current failure probabilities is combined with the parametric measure based on the exponential reliability function, is proposed to estimate and predict the storage reliability of products with possible initial failures, where the non-parametric method is used to estimate the number of failed products and the reliability at each testing time, and the parameter method is used to estimate the initial reliability and the failure rate of storage product. The proposed method has taken into consideration that, the reliability test data of storage products containing the unexamined before and during the storage process, is available for providing more accurate estimates of both the initial failure probability and the storage failure probability. When storage reliability prediction that is the main concern in this field should be made, the non-parametric estimates of failure numbers can be used into the parametric models for the failure process in storage. In the case of exponential models, the assessment and prediction method for storage reliability is presented in this paper. Finally, a numerical example is given to illustrate the method. Furthermore, a detailed comparison between the proposed and traditional method, for examining the rationality of assessment and prediction on the storage reliability, is investigated. The results should be useful for planning a storage environment, decision-making concerning the maximum length of storage, and identifying the production quality. - Highlights: �

Modeling a Predictive Energy Equation Specific for Maintenance Hemodialysis.

Science.gov (United States)

Byham-Gray, Laura D; Parrott, J Scott; Peters, Emily N; Fogerite, Susan Gould; Hand, Rosa K; Ahrens, Sean; Marcus, Andrea Fleisch; Fiutem, Justin J

2017-03-01

Hypermetabolism is theorized in patients diagnosed with chronic kidney disease who are receiving maintenance hemodialysis (MHD). We aimed to distinguish key disease-specific determinants of resting energy expenditure to create a predictive energy equation that more precisely establishes energy needs with the intent of preventing protein-energy wasting. For this 3-year multisite cross-sectional study (N = 116), eligible participants were diagnosed with chronic kidney disease and were receiving MHD for at least 3 months. Predictors for the model included weight, sex, age, C-reactive protein (CRP), glycosylated hemoglobin, and serum creatinine. The outcome variable was measured resting energy expenditure (mREE). Regression modeling was used to generate predictive formulas and Bland-Altman analyses to evaluate accuracy. The majority were male (60.3%), black (81.0%), and non-Hispanic (76.7%), and 23% were ≥65 years old. After screening for multicollinearity, the best predictive model of mREE ( R 2 = 0.67) included weight, age, sex, and CRP. Two alternative models with acceptable predictability ( R 2 = 0.66) were derived with glycosylated hemoglobin or serum creatinine. Based on Bland-Altman analyses, the maintenance hemodialysis equation that included CRP had the best precision, with the highest proportion of participants' predicted energy expenditure classified as accurate (61.2%) and with the lowest number of individuals with underestimation or overestimation. This study confirms disease-specific factors as key determinants of mREE in patients on MHD and provides a preliminary predictive energy equation. Further prospective research is necessary to test the reliability and validity of this equation across diverse populations of patients who are receiving MHD.

A general software reliability process simulation technique

Science.gov (United States)

Tausworthe, Robert C.

1991-01-01

The structure and rationale of the generalized software reliability process, together with the design and implementation of a computer program that simulates this process are described. Given assumed parameters of a particular project, the users of this program are able to generate simulated status timelines of work products, numbers of injected anomalies, and the progress of testing, fault isolation, repair, validation, and retest. Such timelines are useful in comparison with actual timeline data, for validating the project input parameters, and for providing data for researchers in reliability prediction modeling.

Reliability of radiographic observations recorded on a proforma measured using inter- and intra-observer variation: a preliminary study.

Science.gov (United States)

Saunders, M B; Gulabivala, K; Holt, R; Kahan, R S

2000-05-01

The aim of this preliminary study was to test the reliability of radiographic evaluation of features of endodontic interest using a newly devised data collection system. Twelve endodontic MSc postgraduate students and one specialist endodontist examined sample radiographs derived from a random selection of 42 patients seen previously on an Endodontic New Patient Clinic (EDI). Each student examined a random selection of 8-9 roots on periapical radiographs of single- and multirooted teeth, with and without previous root canal therapy and 3-4 dental panoramic tomograms (DPTs). A total of 100 roots were examined. A proforma was used to record observations on 67 radiographic features using predefined criteria. Intra-observer agreement was tested by asking the students to re-examine the radiographs. The principle investigator and the specialist endodontist examined the same radiographs and devised a Gold Standard using the same criteria. This was compared with the student assessments to determine inter-observer variation. The postgraduates then attended a revision session on the use of the form. Each student subsequently examined 8-9 different roots from the pool of radiographs. A further assessment of inter-observer variation was made by comparing these observations with the Gold Standard. Of the 67 radiographic features, only 25 had sufficient response to allow statistical analysis. Kappa values for intra- and inter-observer variation were estimated. These varied depending on the particular radiographic feature being assessed. Fifteen out of 25 intra-observer recordings showed 'good' or 'very good' Kappa agreement, but only three out of 25 inter-observer observations achieved 'good' or 'very good' values. Inter-observer variation was improved following the revision session with 16 out of 25 observations achieving 'good' or 'very good' Kappa agreement. Modification to the proforma, the criteria used, and training for radiographic assessment were considered necessary to

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...

Application of subset simulation in reliability estimation of underground pipelines

International Nuclear Information System (INIS)

Tee, Kong Fah; Khan, Lutfor Rahman; Li, Hongshuang

2014-01-01

This paper presents a computational framework for implementing an advanced Monte Carlo simulation method, called Subset Simulation (SS) for time-dependent reliability prediction of underground flexible pipelines. The SS can provide better resolution for low failure probability level of rare failure events which are commonly encountered in pipeline engineering applications. Random samples of statistical variables are generated efficiently and used for computing probabilistic reliability model. It gains its efficiency by expressing a small probability event as a product of a sequence of intermediate events with larger conditional probabilities. The efficiency of SS has been demonstrated by numerical studies and attention in this work is devoted to scrutinise the robustness of the SS application in pipe reliability assessment and compared with direct Monte Carlo simulation (MCS) method. Reliability of a buried flexible steel pipe with time-dependent failure modes, namely, corrosion induced deflection, buckling, wall thrust and bending stress has been assessed in this study. The analysis indicates that corrosion induced excessive deflection is the most critical failure event whereas buckling is the least susceptible during the whole service life of the pipe. The study also shows that SS is robust method to estimate the reliability of buried pipelines and it is more efficient than MCS, especially in small failure probability prediction

Orthology prediction at scalable resolution by phylogenetic tree analysis

Directory of Open Access Journals (Sweden)

Huynen Martijn A

2007-03-01

Full Text Available Abstract Background Orthology is one of the cornerstones of gene function prediction. Dividing the phylogenetic relations between genes into either orthologs or paralogs is however an oversimplification. Already in two-species gene-phylogenies, the complicated, non-transitive nature of phylogenetic relations results in inparalogs and outparalogs. For situations with more than two species we lack semantics to specifically describe the phylogenetic relations, let alone to exploit them. Published procedures to extract orthologous groups from phylogenetic trees do not allow identification of orthology at various levels of resolution, nor do they document the relations between the orthologous groups. Results We introduce "levels of orthology" to describe the multi-level nature of gene relations. This is implemented in a program LOFT (Levels of Orthology From Trees that assigns hierarchical orthology numbers to genes based on a phylogenetic tree. To decide upon speciation and gene duplication events in a tree LOFT can be instructed either to perform classical species-tree reconciliation or to use the species overlap between partitions in the tree. The hierarchical orthology numbers assigned by LOFT effectively summarize the phylogenetic relations between genes. The resulting high-resolution orthologous groups are depicted in colour, facilitating visual inspection of (large trees. A benchmark for orthology prediction, that takes into account the varying levels of orthology between genes, shows that the phylogeny-based high-resolution orthology assignments made by LOFT are reliable. Conclusion The "levels of orthology" concept offers high resolution, reliable orthology, while preserving the relations between orthologous groups. A Windows as well as a preliminary Java version of LOFT is available from the LOFT website http://www.cmbi.ru.nl/LOFT.

Diesel-generator reliability at nuclear power plants: data and preliminary analysis. Interim report

International Nuclear Information System (INIS)

McClymont, A.; McLagan, G.

1982-06-01

This report summarizes work performed under RP1233-1 relating to the collection and analysis of data pertaining to diesel generator reliability in nuclear power plants. Drawing from data collected on-site at plants, data supplied by utilites, and data from Licensee Event Reports (LERs), the report describes methods of deriving reliability estimates from data for use in probabilistic risk assessment and presents results when these methods are applied to data collected from 14 plants. Specifically, data are used to estimate diesel failure probabilities for failures to start and failure rates for failures to continue to run. A sampling theory approach and a Bayesian approach to failure probability estimation are compared. The data are used to derive estimates of diesel repair time for some plants, maintenance outages, and multiple diesel failure rates. In addition, a section is included that presents suggestions for failure-rate estimation when an accurate count of diesel start attempts at a plant is not available. The final section presents an analysis of diesel failures based on data from LERs, including a breakdown of failure event by subsystem, failure mode, and failure cause. Appendixes include detailed summaries of the data used in the analysis of previous sections

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.

Proceedings of the SRESA national conference on reliability and safety engineering

International Nuclear Information System (INIS)

Varde, P.V.; Vaishnavi, P.; Sujatha, S.; Valarmathi, A.

2014-01-01

The objective of this conference was to provide a forum for technical discussions on recent developments in the area of risk based approach and Prognostic Health Management of critical systems in decision making. The reliability and safety engineering methods are concerned with the way which the product fails, and the effects of failure is to understand how a product works and assures acceptable levels of safety. The reliability engineering addresses all the anticipated and possibly unanticipated causes of failure to ensure the occurrence of failure is prevented or minimized. The topics discussed in the conference were: Reliability in Engineering Design, Safety Assessment and Management, Reliability analysis and Assessment , Stochastic Petri nets for reliability Modeling, Dynamic Reliability, Reliability Prediction, Hardware Reliability, Software Reliability in Safety Critical Issues, Probabilistic Safety Assessment, Risk Informed Approach, Dynamic Models for Reliability Analysis, Reliability based Design and Analysis, Prognostics and Health Management, Remaining Useful Life (RUL), Human Reliability Modeling, Risk Based Applications, Hazard and Operability Study (HAZOP), Reliability in Network Security and Quality Assurance and Management etc. The papers relevant to INIS are indexed separately

Ventromedial Prefrontal Cortex Activation Is Associated with Memory Formation for Predictable Rewards

Science.gov (United States)

Bialleck, Katharina A.; Schaal, Hans-Peter; Kranz, Thorsten A.; Fell, Juergen; Elger, Christian E.; Axmacher, Nikolai

2011-01-01

During reinforcement learning, dopamine release shifts from the moment of reward consumption to the time point when the reward can be predicted. Previous studies provide consistent evidence that reward-predicting cues enhance long-term memory (LTM) formation of these items via dopaminergic projections to the ventral striatum. However, it is less clear whether memory for items that do not precede a reward but are directly associated with reward consumption is also facilitated. Here, we investigated this question in an fMRI paradigm in which LTM for reward-predicting and neutral cues was compared to LTM for items presented during consumption of reliably predictable as compared to less predictable rewards. We observed activation of the ventral striatum and enhanced memory formation during reward anticipation. During processing of less predictable as compared to reliably predictable rewards, the ventral striatum was activated as well, but items associated with less predictable outcomes were remembered worse than items associated with reliably predictable outcomes. Processing of reliably predictable rewards activated the ventromedial prefrontal cortex (vmPFC), and vmPFC BOLD responses were associated with successful memory formation of these items. Taken together, these findings show that consumption of reliably predictable rewards facilitates LTM formation and is associated with activation of the vmPFC. PMID:21326612

Human reliability analysis of control room operators

Energy Technology Data Exchange (ETDEWEB)

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

2005-07-01

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

Quantifiable and Reliable Structural Health Management Systems, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Major concerns for implementing a practical built-in structural health monitoring system are prediction accuracy and data reliability. It is proposed to develop...

Semiconductor measurement technology: reliability technology for cardiac pacemakers 2: a workshop report, 1976

International Nuclear Information System (INIS)

Schafft, H.A.

1977-01-01

Summaries are presented of 12 invited talks on the following topics: the procurement and assurance of high reliability electronic parts, leak rate and moisture measurements, pacemaker batteries, and pacemaker leads. The workshop, second in a series, was held in response to strong interest expressed by the pacemaker community to address technical questions relevant to the enhancement and assurance of cardiac pacemaker reliability. Discussed at the workshop were a process validation wafer concept for assuring process uniformity in device chips; screen tests for assuring reliable electronic parts; reliability prediction; reliability comparison of semiconductor technologies; mechanisms of short-circuiting dendritic growths; details of helium and radioisotope leak test methods; a study to correlate package leak rates, as measured with test gasses, and actual moisture infusion; battery life prediction; microcalorimetric measurements to nondestructively evaluate batteries for pacemakers; and an engineer's and a physician's view of the present status of pacemaker leads. References are included with most of the reports

Reliability Estimation for Single-unit Ceramic Crown Restorations

Science.gov (United States)

Lekesiz, H.

2014-01-01

The objective of this study was to evaluate the potential of a survival prediction method for the assessment of ceramic dental restorations. For this purpose, fast-fracture and fatigue reliabilities for 2 bilayer (metal ceramic alloy core veneered with fluorapatite leucite glass-ceramic, d.Sign/d.Sign-67, by Ivoclar; glass-infiltrated alumina core veneered with feldspathic porcelain, VM7/In-Ceram Alumina, by Vita) and 3 monolithic (leucite-reinforced glass-ceramic, Empress, and ProCAD, by Ivoclar; lithium-disilicate glass-ceramic, Empress 2, by Ivoclar) single posterior crown restorations were predicted, and fatigue predictions were compared with the long-term clinical data presented in the literature. Both perfectly bonded and completely debonded cases were analyzed for evaluation of the influence of the adhesive/restoration bonding quality on estimations. Material constants and stress distributions required for predictions were calculated from biaxial tests and finite element analysis, respectively. Based on the predictions, In-Ceram Alumina presents the best fast-fracture resistance, and ProCAD presents a comparable resistance for perfect bonding; however, ProCAD shows a significant reduction of resistance in case of complete debonding. Nevertheless, it is still better than Empress and comparable with Empress 2. In-Ceram Alumina and d.Sign have the highest long-term reliability, with almost 100% survivability even after 10 years. When compared with clinical failure rates reported in the literature, predictions show a promising match with clinical data, and this indicates the soundness of the settings used in the proposed predictions. PMID:25048249

Preliminary design and definition of field experiments for welded tuff rock mechanics program

International Nuclear Information System (INIS)

Zimmerman, R.M.

1982-06-01

The preliminary design contains objectives, typical experiment layouts, definitions of equipment and instrumentation, test matrices, preliminary design predictive modeling results for five experiments, and a definition of the G-Tunnel Underground Facility (GTUF) at the Nevada Test Site where the experiments are to be located. Experiments described for investigations in welded tuff are the Small Diameter Heater, Unit Cell-Canister Scale, Heated Block, Rocha Slot, and Miniature Heater

Reliability of clinical ICD-10 schizophrenia diagnoses

DEFF Research Database (Denmark)

Jakobsen, Klaus D; Frederiksen, Julie N; Hansen, Thomas

2005-01-01

Concern has been expressed as to the reliability of clinical ICD-10 diagnosis of schizophrenia. This study was designed to assess the diagnostic reliability of the clinical ICD-10 diagnosis of schizophrenia in a random sample of Danish in- and outpatients with a history of psychosis. A sample...... value (87%) of ICD-10 schizophrenia and an overall good agreement between clinical and OPCRIT-derived diagnoses (kappa=0.60). An even higher positive predictive value was obtained when diagnoses were amalgamated into a diagnostic entity of schizophrenia-spectrum disorders (98%). Near perfect agreement...... was seen between OPCRIT-derived ICD-10 and DSM-IV diagnoses (kappa=0.87). Thus, this study demonstrates high reliability of the clinical diagnosis of schizophrenia and even more so of the diagnosis of schizophrenia-spectrum disorder....

HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 4: HARP Output (HARPO) graphics display user's guide

Science.gov (United States)

Sproles, Darrell W.; Bavuso, Salvatore J.

1994-01-01

The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. HiRel consists of interactive graphical input/output programs and four reliability/availability modeling engines that provide analytical and simulative solutions to a wide host of highly reliable fault-tolerant system architectures and is also applicable to electronic systems in general. The tool system was designed at the outset to be compatible with most computing platforms and operating systems and some programs have been beta tested within the aerospace community for over 8 years. This document is a user's guide for the HiRel graphical postprocessor program HARPO (HARP Output). HARPO reads ASCII files generated by HARP. It provides an interactive plotting capability that can be used to display alternate model data for trade-off analyses. File data can also be imported to other commercial software programs.

Earthquake prediction

International Nuclear Information System (INIS)

Ward, P.L.

1978-01-01

The state of the art of earthquake prediction is summarized, the possible responses to such prediction are examined, and some needs in the present prediction program and in research related to use of this new technology are reviewed. Three basic aspects of earthquake prediction are discussed: location of the areas where large earthquakes are most likely to occur, observation within these areas of measurable changes (earthquake precursors) and determination of the area and time over which the earthquake will occur, and development of models of the earthquake source in order to interpret the precursors reliably. 6 figures

HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 3: HARP Graphics Oriented (GO) input user's guide

Science.gov (United States)

Bavuso, Salvatore J.; Rothmann, Elizabeth; Mittal, Nitin; Koppen, Sandra Howell

1994-01-01

The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. HiRel consists of interactive graphical input/output programs and four reliability/availability modeling engines that provide analytical and simulative solutions to a wide host of highly reliable fault-tolerant system architectures and is also applicable to electronic systems in general. The tool system was designed at the outset to be compatible with most computing platforms and operating systems, and some programs have been beta tested within the aerospace community for over 8 years. This document is a user's guide for the HiRel graphical preprocessor Graphics Oriented (GO) program. GO is a graphical user interface for the HARP engine that enables the drawing of reliability/availability models on a monitor. A mouse is used to select fault tree gates or Markov graphical symbols from a menu for drawing.

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

Science.gov (United States)

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

2012-01-01

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

Predicting climate-induced range shifts: model differences and model reliability.

Science.gov (United States)

Joshua J. Lawler; Denis White; Ronald P. Neilson; Andrew R. Blaustein

2006-01-01

Predicted changes in the global climate are likely to cause large shifts in the geographic ranges of many plant and animal species. To date, predictions of future range shifts have relied on a variety of modeling approaches with different levels of model accuracy. Using a common data set, we investigated the potential implications of alternative modeling approaches for...

Survey of methods used to asses human reliability in the human factors reliability benchmark exercise

International Nuclear Information System (INIS)

Poucet, A.

1988-01-01

The Joint Research Centre of the European Commission has organised a Human Factors Reliability Benchmark Exercise (HF-RBE) with the aim to assess the state-of-the-art in human reliability modelling and assessment. Fifteen teams from eleven countries, representing industry, utilities, licensing organisations and research institutes, participate in the HF-RBE, which is organised around two study cases: (1) analysis of routine functional test and maintenance procedures, with the aim to assess the probability of test-induced failures, the probability of failures to remain unrevealed, and the potential to initiate transients because of errors performed in the test; and (2) analysis of human actions during an operational transient, with the aim to assess the probability that the operators will correctly diagnose the malfunctions and take proper corrective action. The paper briefly reports how the HF-RBE was structured and gives an overview of the methods that have been used for predicting human reliability in both study cases. The experience in applying these methods is discussed and the results obtained are compared. (author)

A Report on Simulation-Driven Reliability and Failure Analysis of Large-Scale Storage Systems

Energy Technology Data Exchange (ETDEWEB)

Wan, Lipeng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Feiyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oral, H. Sarp [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Vazhkudai, Sudharshan S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cao, Qing [Univ. of Tennessee, Knoxville, TN (United States)

2014-11-01

High-performance computing (HPC) storage systems provide data availability and reliability using various hardware and software fault tolerance techniques. Usually, reliability and availability are calculated at the subsystem or component level using limited metrics such as, mean time to failure (MTTF) or mean time to data loss (MTTDL). This often means settling on simple and disconnected failure models (such as exponential failure rate) to achieve tractable and close-formed solutions. However, such models have been shown to be insufficient in assessing end-to-end storage system reliability and availability. We propose a generic simulation framework aimed at analyzing the reliability and availability of storage systems at scale, and investigating what-if scenarios. The framework is designed for an end-to-end storage system, accommodating the various components and subsystems, their interconnections, failure patterns and propagation, and performs dependency analysis to capture a wide-range of failure cases. We evaluate the framework against a large-scale storage system that is in production and analyze its failure projections toward and beyond the end of lifecycle. We also examine the potential operational impact by studying how different types of components affect the overall system reliability and availability, and present the preliminary results

A discrete-time Bayesian network reliability modeling and analysis framework

International Nuclear Information System (INIS)

Boudali, H.; Dugan, J.B.

2005-01-01

Dependability tools are becoming an indispensable tool for modeling and analyzing (critical) systems. However the growing complexity of such systems calls for increasing sophistication of these tools. Dependability tools need to not only capture the complex dynamic behavior of the system components, but they must be also easy to use, intuitive, and computationally efficient. In general, current tools have a number of shortcomings including lack of modeling power, incapacity to efficiently handle general component failure distributions, and ineffectiveness in solving large models that exhibit complex dependencies between their components. We propose a novel reliability modeling and analysis framework based on the Bayesian network (BN) formalism. The overall approach is to investigate timed Bayesian networks and to find a suitable reliability framework for dynamic systems. We have applied our methodology to two example systems and preliminary results are promising. We have defined a discrete-time BN reliability formalism and demonstrated its capabilities from a modeling and analysis point of view. This research shows that a BN based reliability formalism is a powerful potential solution to modeling and analyzing various kinds of system components behaviors and interactions. Moreover, being based on the BN formalism, the framework is easy to use and intuitive for non-experts, and provides a basis for more advanced and useful analyses such as system diagnosis

Deep learning-based features of breast MRI for prediction of occult invasive disease following a diagnosis of ductal carcinoma in situ: preliminary data

Science.gov (United States)

Zhu, Zhe; Harowicz, Michael; Zhang, Jun; Saha, Ashirbani; Grimm, Lars J.; Hwang, Shelley; Mazurowski, Maciej A.

2018-02-01

Approximately 25% of patients with ductal carcinoma in situ (DCIS) diagnosed from core needle biopsy are subsequently upstaged to invasive cancer at surgical excision. Identifying patients with occult invasive disease is important as it changes treatment and precludes enrollment in active surveillance for DCIS. In this study, we investigated upstaging of DCIS to invasive disease using deep features. While deep neural networks require large amounts of training data, the available data to predict DCIS upstaging is sparse and thus directly training a neural network is unlikely to be successful. In this work, a pre-trained neural network is used as a feature extractor and a support vector machine (SVM) is trained on the extracted features. We used the dynamic contrast-enhanced (DCE) MRIs of patients at our institution from January 1, 2000, through March 23, 2014 who underwent MRI following a diagnosis of DCIS. Among the 131 DCIS patients, there were 35 patients who were upstaged to invasive cancer. Area under the ROC curve within the 10-fold cross-validation scheme was used for validation of our predictive model. The use of deep features was able to achieve an AUC of 0.68 (95% CI: 0.56-0.78) to predict occult invasive disease. This preliminary work demonstrates the promise of deep features to predict surgical upstaging following a diagnosis of DCIS.

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...

Stochastic models in reliability and maintenance

CERN Document Server

2002-01-01

Our daily lives can be maintained by the high-technology systems. Computer systems are typical examples of such systems. We can enjoy our modern lives by using many computer systems. Much more importantly, we have to maintain such systems without failure, but cannot predict when such systems will fail and how to fix such systems without delay. A stochastic process is a set of outcomes of a random experiment indexed by time, and is one of the key tools needed to analyze the future behavior quantitatively. Reliability and maintainability technologies are of great interest and importance to the maintenance of such systems. Many mathematical models have been and will be proposed to describe reliability and maintainability systems by using the stochastic processes. The theme of this book is "Stochastic Models in Reliability and Main­ tainability. " This book consists of 12 chapters on the theme above from the different viewpoints of stochastic modeling. Chapter 1 is devoted to "Renewal Processes," under which cla...

Assessing internet addiction using the parsimonious internet addiction components model—A preliminary study.

OpenAIRE

Kuss, D.J.; Shorter, G.W.; Rooij, A.J. van; Griffiths, M.D.; Schoenmakers, T.M.

2014-01-01

Internet usage has grown exponentially over the last decade. Research indicates that excessive Internet use can lead to symptoms associated with addiction. To date, assessment of potential Internet addiction has varied regarding populations studied and instruments used, making reliable prevalence estimations difficult. To overcome the present problems a preliminary study was conducted testing a parsimonious Internet addiction components model based on Griffiths’ addiction components (Journal ...

The development of a preliminary ultrasonographic scoring system for features of hand osteoarthritis.

LENUS (Irish Health Repository)

Keen, H I

2008-05-01

Painful osteoarthritis (OA) of the hand is common and a validated ultrasound (US) scoring system would be valuable for epidemiological and therapeutic outcome studies. US is increasingly used to assess peripheral joints, though most of the US focus in rheumatic diseases has been on rheumatoid arthritis. We aimed to develop a preliminary US hand OA scoring system, initially focusing on relevant pathological features with potentially high reliability.

Reliability of supply in competitive electricity markets: The Nordic electricity Market

International Nuclear Information System (INIS)

Singh, Balbir

2005-12-01

An overview of the current regulation and performance of the network utilities with respect to the reliability of supply across Europe in general indicates wide variation. On the regional level the situation in the Nordic market is no exception. Can the variation in reliability of supply in Nordic region be explained by differences in regulatory frameworks in the Nordic countries and is it possible to draw any best practice lessons for other countries and regions? The Norwegian regulation and performance with respect to reliability criterion is encouraging, however it must be emphasized that the Norwegian experience with reliability regulation in its current form covers a period of 3 years, a period that is too short to evaluate the Norwegian model. A closer examination of the Norwegian model reveals dynamic trade off in reliability performance, which if permanent may endanger the reliability of supply in the long-run. Last, but not the least important is the criterion that choice of regulation should be based on a careful social cost-benefit analysis of the regulatory model where both cost incurred by the regulatory agencies and the compliance costs incurred by the regulated utilities are included. A preliminary analysis of regulatory agencies in the Nordic market indicates that Norwegian model of network regulation is quite resource incentive. While it is premature to draw conclusions about the national regulatory mechanisms, the Nordic cross border regulation through voluntary arrangements under the auspices of NORDEL provides a good example of an arrangement that is useful when implementation of a formal regulatory regime across different jurisdiction is not possible

Reasoning with Inductive Argument Test: A Study of Validity and Reliability

Directory of Open Access Journals (Sweden)

Mehmet Emrah Karadere

2013-11-01

Full Text Available Reasoning with Inductive Argument Test:A Study of Validity and Reliability Objective: The aim of our study is to research reliability and validity and to evaluate the usability of Turkish version of Reasoning with Inductive Argument Test (RIAT in Turkish healty population. Method: 51 healty volunteers who work in Ankara Dıskapi Yildirim Beyazit Research and Training Hospital participated in this study. Reasoning with Inductive Argument Test (RIAT was translated into Turkish by three clinical good knowledge of English. Participants were given a sociodemographic data form, and RIAT were performed by clinicians. To test the reliability of the Turkish version of RIAT, Cronbach’s alpha coefficient was calculated and the halving method was used for the test. Results: The internal consistency of the Reasoning with Inductive Argument Test (RIAT items, Cronbach’s alpha internal consistency coefficient measurements of 0.73 was found to be statistically significant. Spearman-Brown coefficient that determines the reliability of the whole test r=0.74 was found. Kurtosis values of all the items was below 1.5 and the percentages in the second evaluation were mainly lower. At the same time, both change in belief between self produced RIAT options and given RIAT options (p=0.02, z=-2296 as well as changes in beliefs between related and unrelated items for Obsessive Compulsive Disorder (OCD difference (p=0.03, z=-2.199 were significant. Conclusion: The preliminary data obtained from the study of reliability and validity of the scale shows that ‘Reasoning with Inductive Argument Test’ supports reliability and validity in Turkish population.

Prediction of Aerodynamic Coefficient using Genetic Algorithm Optimized Neural Network for Sparse Data

Science.gov (United States)

Rajkumar, T.; Bardina, Jorge; Clancy, Daniel (Technical Monitor)

2002-01-01

Wind tunnels use scale models to characterize aerodynamic coefficients, Wind tunnel testing can be slow and costly due to high personnel overhead and intensive power utilization. Although manual curve fitting can be done, it is highly efficient to use a neural network to define the complex relationship between variables. Numerical simulation of complex vehicles on the wide range of conditions required for flight simulation requires static and dynamic data. Static data at low Mach numbers and angles of attack may be obtained with simpler Euler codes. Static data of stalled vehicles where zones of flow separation are usually present at higher angles of attack require Navier-Stokes simulations which are costly due to the large processing time required to attain convergence. Preliminary dynamic data may be obtained with simpler methods based on correlations and vortex methods; however, accurate prediction of the dynamic coefficients requires complex and costly numerical simulations. A reliable and fast method of predicting complex aerodynamic coefficients for flight simulation I'S presented using a neural network. The training data for the neural network are derived from numerical simulations and wind-tunnel experiments. The aerodynamic coefficients are modeled as functions of the flow characteristics and the control surfaces of the vehicle. The basic coefficients of lift, drag and pitching moment are expressed as functions of angles of attack and Mach number. The modeled and training aerodynamic coefficients show good agreement. This method shows excellent potential for rapid development of aerodynamic models for flight simulation. Genetic Algorithms (GA) are used to optimize a previously built Artificial Neural Network (ANN) that reliably predicts aerodynamic coefficients. Results indicate that the GA provided an efficient method of optimizing the ANN model to predict aerodynamic coefficients. The reliability of the ANN using the GA includes prediction of aerodynamic

Preliminary design of reactor coolant pump canned motor for AC600

International Nuclear Information System (INIS)

Deng Shaowen

1998-01-01

The reactor coolant pump canned motor of AC600 PWR is the kind of shielded motors with high moment of inertia, high reliability, high efficiency and nice starting performance. The author briefly presents the main feature, design criterion and technical requirements, preliminary design, computation results and analysis of performance of AC600 reactor coolant pump canned motor, and proposes some problems to be solved for study and design of AC600 reactor coolant pump canned motor

Product reliability and thin-film photovoltaics

Science.gov (United States)

Gaston, Ryan; Feist, Rebekah; Yeung, Simon; Hus, Mike; Bernius, Mark; Langlois, Marc; Bury, Scott; Granata, Jennifer; Quintana, Michael; Carlson, Carl; Sarakakis, Georgios; Ogden, Douglas; Mettas, Adamantios

2009-08-01

Despite significant growth in photovoltaics (PV) over the last few years, only approximately 1.07 billion kWhr of electricity is estimated to have been generated from PV in the US during 2008, or 0.27% of total electrical generation. PV market penetration is set for a paradigm shift, as fluctuating hydrocarbon prices and an acknowledgement of the environmental impacts associated with their use, combined with breakthrough new PV technologies, such as thin-film and BIPV, are driving the cost of energy generated with PV to parity or cost advantage versus more traditional forms of energy generation. In addition to reaching cost parity with grid supplied power, a key to the long-term success of PV as a viable energy alternative is the reliability of systems in the field. New technologies may or may not have the same failure modes as previous technologies. Reliability testing and product lifetime issues continue to be one of the key bottlenecks in the rapid commercialization of PV technologies today. In this paper, we highlight the critical need for moving away from relying on traditional qualification and safety tests as a measure of reliability and focus instead on designing for reliability and its integration into the product development process. A drive towards quantitative predictive accelerated testing is emphasized and an industrial collaboration model addressing reliability challenges is proposed.

Preliminary hazard analysis for the Brayton Isotope Ground Demonstration System (including vacuum test chamber)

International Nuclear Information System (INIS)

Miller, L.G.

1975-01-01

The Preliminary Hazard Analysis (PHA) of the BIPS-GDS is a tabular summary of hazards and undesired events which may lead to system damage or failure and/or hazard to personnel. The PHA reviews the GDS as it is envisioned to operate in the Vacuum Test Chamber (VTC) of the GDS Test Facility. The VTC and other equipment which will comprise the test facility are presently in an early stage of preliminary design and will undoubtedly undergo numerous changes before the design is frozen. The PHA and the FMECA to follow are intended to aid the design effort by identifying areas of concern which are critical to the safety and reliability of the BIPS-GDS and test facility

Psychometrics Matter in Health Behavior: A Long-term Reliability Generalization Study.

Science.gov (United States)

Pickett, Andrew C; Valdez, Danny; Barry, Adam E

2017-09-01

Despite numerous calls for increased understanding and reporting of reliability estimates, social science research, including the field of health behavior, has been slow to respond and adopt such practices. Therefore, we offer a brief overview of reliability and common reporting errors; we then perform analyses to examine and demonstrate the variability of reliability estimates by sample and over time. Using meta-analytic reliability generalization, we examined the variability of coefficient alpha scores for a well-designed, consistent, nationwide health study, covering a span of nearly 40 years. For each year and sample, reliability varied. Furthermore, reliability was predicted by a sample characteristic that differed among age groups within each administration. We demonstrated that reliability is influenced by the methods and individuals from which a given sample is drawn. Our work echoes previous calls that psychometric properties, particularly reliability of scores, are important and must be considered and reported before drawing statistical conclusions.

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

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

Science.gov (United States)

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

2017-01-01

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

Preliminary results of an attempt to provide soil moisture datasets in order to verify numerical weather prediction models

International Nuclear Information System (INIS)

Cassardo, C.; Loglisci, N.

2005-01-01

In the recent years, there has been a significant growth in the recognition of the soil moisture importance in large-scale hydrology and climate modelling. Soil moisture is a lower boundary condition, which rules the partitioning of energy in terms of sensible and latent heat flux. Wrong estimations of soil moisture lead to wrong simulation of the surface layer evolution and hence precipitations and cloud cover forecasts could be consequently affected. This is true for large scale medium-range weather forecasts as well as for local-scale short range weather forecasts, particularly in those situations in which local convection is well developed. Unfortunately; despite the importance of this physical parameter there are only few soil moisture data sets sparse in time and in space around in the world. Due to this scarcity of soil moisture observations, we developed an alternative method to provide soil moisture datasets in order to verify numerical weather prediction models. In this paper are presented the preliminary results of an attempt to verify soil moisture fields predicted by a mesoscale model. The data for the comparison were provided by the simulations of the diagnostic land surface scheme LSPM (Land Surface Process Model), widely used at the Piedmont Regional Weather Service for agro-meteorological purposes. To this end, LSPM was initialized and driven by Synop observations, while the surface (vegetation and soil) parameter values were initialized by ECOCLIMAP global dataset at 1km 2 resolution

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

Systems reliability/structural reliability

International Nuclear Information System (INIS)

Green, A.E.

1980-01-01

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

MEMS Reliability: Infrastructure, Test Structures, Experiments, and Failure Modes

Energy Technology Data Exchange (ETDEWEB)

TANNER,DANELLE M.; SMITH,NORMAN F.; IRWIN,LLOYD W.; EATON,WILLIAM P.; HELGESEN,KAREN SUE; CLEMENT,J. JOSEPH; MILLER,WILLIAM M.; MILLER,SAMUEL L.; DUGGER,MICHAEL T.; WALRAVEN,JEREMY A.; PETERSON,KENNETH A.

2000-01-01

The burgeoning new technology of Micro-Electro-Mechanical Systems (MEMS) shows great promise in the weapons arena. We can now conceive of micro-gyros, micro-surety systems, and micro-navigators that are extremely small and inexpensive. Do we want to use this new technology in critical applications such as nuclear weapons? This question drove us to understand the reliability and failure mechanisms of silicon surface-micromachined MEMS. Development of a testing infrastructure was a crucial step to perform reliability experiments on MEMS devices and will be reported here. In addition, reliability test structures have been designed and characterized. Many experiments were performed to investigate failure modes and specifically those in different environments (humidity, temperature, shock, vibration, and storage). A predictive reliability model for wear of rubbing surfaces in microengines was developed. The root causes of failure for operating and non-operating MEMS are discussed. The major failure mechanism for operating MEMS was wear of the polysilicon rubbing surfaces. Reliability design rules for future MEMS devices are established.

Radiomic features from the peritumoral brain parenchyma on treatment-naive multi-parametric MR imaging predict long versus short-term survival in glioblastoma multiforme: Preliminary findings

Energy Technology Data Exchange (ETDEWEB)

Prasanna, Prateek; Patel, Jay; Madabhushi, Anant; Tiwari, Pallavi [Case Western Reserve University, Department of Biomedical Engineering, Cleveland, OH (United States); Partovi, Sasan [University Hospitals Case Medical Center, Case Western Reserve School of Medicine, Cleveland, OH (United States)

2017-10-15

Despite 90 % of glioblastoma (GBM) recurrences occurring in the peritumoral brain zone (PBZ), its contribution in patient survival is poorly understood. The current study leverages computerized texture (i.e. radiomic) analysis to evaluate the efficacy of PBZ features from pre-operative MRI in predicting long- (>18 months) versus short-term (<7 months) survival in GBM. Sixty-five patient examinations (29 short-term, 36 long-term) with gadolinium-contrast T{sub 1w}, FLAIR and T{sub 2w} sequences from the Cancer Imaging Archive were employed. An expert manually segmented each study as: enhancing lesion, PBZ and tumour necrosis. 402 radiomic features (capturing co-occurrence, grey-level dependence and directional gradients) were obtained for each region. Evaluation was performed using threefold cross-validation, such that a subset of studies was used to select the most predictive features, and the remaining subset was used to evaluate their efficacy in predicting survival. A subset of ten radiomic 'peritumoral' MRI features, suggestive of intensity heterogeneity and textural patterns, was found to be predictive of survival (p = 1.47 x 10{sup -5}) as compared to features from enhancing tumour, necrotic regions and known clinical factors. Our preliminary analysis suggests that radiomic features from the PBZ on routine pre-operative MRI may be predictive of long- versus short-term survival in GBM. (orig.)

Reliability Engineering

International Nuclear Information System (INIS)

Lee, Sang Yong

1992-07-01

This book is about reliability engineering, which describes definition and importance of reliability, development of reliability engineering, failure rate and failure probability density function about types of it, CFR and index distribution, IFR and normal distribution and Weibull distribution, maintainability and movability, reliability test and reliability assumption in index distribution type, normal distribution type and Weibull distribution type, reliability sampling test, reliability of system, design of reliability and functionality failure analysis by FTA.

Reliability and radiation tolerance of robots for nuclear applications

Energy Technology Data Exchange (ETDEWEB)

Lauridsen, K [Risoe National Lab. (Denmark); Decreton, M [SCK.CEN (Belgium); Seifert, C C [Siemens AG (Germany); Sharp, R [AEA Technology (United Kingdom)

1996-10-01

The reliability of a robot for nuclear applications will be affected by environmental factors such as dust, water, vibrations, heat, and, in particular, ionising radiation. The present report describes the work carried out in a project addressing the reliability and radiation tolerance of such robots. A widely representative range of components and materials has been radiation tested and the test results have been collated in a database along with data provided by the participants from earlier work and data acquired from other sources. A radiation effects guide has been written for the use by designers of electronic equipment for robots. A generic reliability model has been set up together with generic failure strategies, forming the basis for specific reliability modelling carried out in other projects. Modelling tools have been examined and developed for the prediction of the performance of electronic circuits subjected to radiation. Reports have been produced dealing with the prediction and detection of upcoming failures in electronic systems. Operational experience from the use of robots in radiation work in various contexts has been compiled in a report, and another report has been written on cost/benefit considerations about the use of robots. Also the possible impact of robots on the safety of the surrounding plant has been considered and reported. (au) 16 ills., 236 refs.

Maximum Entropy Discrimination Poisson Regression for Software Reliability Modeling.

Science.gov (United States)

Chatzis, Sotirios P; Andreou, Andreas S

2015-11-01

Reliably predicting software defects is one of the most significant tasks in software engineering. Two of the major components of modern software reliability modeling approaches are: 1) extraction of salient features for software system representation, based on appropriately designed software metrics and 2) development of intricate regression models for count data, to allow effective software reliability data modeling and prediction. Surprisingly, research in the latter frontier of count data regression modeling has been rather limited. More specifically, a lack of simple and efficient algorithms for posterior computation has made the Bayesian approaches appear unattractive, and thus underdeveloped in the context of software reliability modeling. In this paper, we try to address these issues by introducing a novel Bayesian regression model for count data, based on the concept of max-margin data modeling, effected in the context of a fully Bayesian model treatment with simple and efficient posterior distribution updates. Our novel approach yields a more discriminative learning technique, making more effective use of our training data during model inference. In addition, it allows of better handling uncertainty in the modeled data, which can be a significant problem when the training data are limited. We derive elegant inference algorithms for our model under the mean-field paradigm and exhibit its effectiveness using the publicly available benchmark data sets.

Reliability and radiation tolerance of robots for nuclear applications

International Nuclear Information System (INIS)

Lauridsen, K.; Decreton, M.; Seifert, C.C.; Sharp, R.

1996-10-01

The reliability of a robot for nuclear applications will be affected by environmental factors such as dust, water, vibrations, heat, and, in particular, ionising radiation. The present report describes the work carried out in a project addressing the reliability and radiation tolerance of such robots. A widely representative range of components and materials has been radiation tested and the test results have been collated in a database along with data provided by the participants from earlier work and data acquired from other sources. A radiation effects guide has been written for the use by designers of electronic equipment for robots. A generic reliability model has been set up together with generic failure strategies, forming the basis for specific reliability modelling carried out in other projects. Modelling tools have been examined and developed for the prediction of the performance of electronic circuits subjected to radiation. Reports have been produced dealing with the prediction and detection of upcoming failures in electronic systems. Operational experience from the use of robots in radiation work in various contexts has been compiled in a report, and another report has been written on cost/benefit considerations about the use of robots. Also the possible impact of robots on the safety of the surrounding plant has been considered and reported. (au) 16 ills., 236 refs

On the accuracy and reliability of predictions by control-system theory.

Science.gov (United States)

Bourbon, W T; Copeland, K E; Dyer, V R; Harman, W K; Mosley, B L

1990-12-01

In three experiments we used control-system theory (CST) to predict the results of tracking tasks on which people held a handle to keep a cursor even with a target on a computer screen. 10 people completed a total of 104 replications of the task. In each experiment, there were two conditions: in one, only the handle affected the position of the cursor; in the other, a random disturbance also affected the cursor. From a person's performance during Condition 1, we derived constants used in the CST model to predict the results of Condition 2. In two experiments, predictions occurred a few minutes before Condition 2; in one experiment, the delay was 1 yr. During a 1-min. experimental run, the positions of handle and cursor, produced by the person, were each sampled 1800 times, once every 1/30 sec. During a modeling run, the model predicted the positions of the handle and target for each of the 1800 intervals sampled in the experimental run. In 104 replications, the mean correlation between predicted and actual positions of the handle was .996; SD = .002.

A PRELIMINARY JUPITER MODEL

International Nuclear Information System (INIS)

Hubbard, W. B.; Militzer, B.

2016-01-01

In anticipation of new observational results for Jupiter's axial moment of inertia and gravitational zonal harmonic coefficients from the forthcoming Juno orbiter, we present a number of preliminary Jupiter interior models. We combine results from ab initio computer simulations of hydrogen–helium mixtures, including immiscibility calculations, with a new nonperturbative calculation of Jupiter's zonal harmonic coefficients, to derive a self-consistent model for the planet's external gravity and moment of inertia. We assume helium rain modified the interior temperature and composition profiles. Our calculation predicts zonal harmonic values to which measurements can be compared. Although some models fit the observed (pre-Juno) second- and fourth-order zonal harmonics to within their error bars, our preferred reference model predicts a fourth-order zonal harmonic whose absolute value lies above the pre-Juno error bars. This model has a dense core of about 12 Earth masses and a hydrogen–helium-rich envelope with approximately three times solar metallicity

A PRELIMINARY JUPITER MODEL

Energy Technology Data Exchange (ETDEWEB)

Hubbard, W. B. [Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Militzer, B. [Department of Earth and Planetary Science, Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

2016-03-20

In anticipation of new observational results for Jupiter's axial moment of inertia and gravitational zonal harmonic coefficients from the forthcoming Juno orbiter, we present a number of preliminary Jupiter interior models. We combine results from ab initio computer simulations of hydrogen–helium mixtures, including immiscibility calculations, with a new nonperturbative calculation of Jupiter's zonal harmonic coefficients, to derive a self-consistent model for the planet's external gravity and moment of inertia. We assume helium rain modified the interior temperature and composition profiles. Our calculation predicts zonal harmonic values to which measurements can be compared. Although some models fit the observed (pre-Juno) second- and fourth-order zonal harmonics to within their error bars, our preferred reference model predicts a fourth-order zonal harmonic whose absolute value lies above the pre-Juno error bars. This model has a dense core of about 12 Earth masses and a hydrogen–helium-rich envelope with approximately three times solar metallicity.

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

. The results provided by the present work show that the data assimilation approach implemented leads to a significant enhancement of the reliability of the numerical wave predictions. The work is still ongoing, and besides the fact that all the satellites are now considered for assimilation, the scheme is also adapted in order to be able to provide forecast products. Keywords: Black Sea, wave models, SWAN, data assimilation, satellite data. ACKNOWLEDGEMENT: This work was supported by a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0089 (project DAMWAVE).

Flood design recipes vs. reality: can predictions for ungauged basins be trusted?

Science.gov (United States)

Efstratiadis, A.; Koussis, A. D.; Koutsoyiannis, D.; Mamassis, N.

2013-12-01

Despite the great scientific and technological advances in flood hydrology, everyday engineering practices still follow simplistic approaches, such as the rational formula and the SCS-CN method combined with the unit hydrograph theory that are easy to formally implement in ungauged areas. In general, these "recipes" have been developed many decades ago, based on field data from few experimental catchments. However, many of them have been neither updated nor validated across all hydroclimatic and geomorphological conditions. This has an obvious impact on the quality and reliability of hydrological studies, and, consequently, on the safety and cost of the related flood protection works. Preliminary results, based on historical flood data from Cyprus and Greece, indicate that a substantial revision of many aspects of flood engineering procedures is required, including the regionalization formulas as well as the modelling concepts themselves. In order to provide a consistent design framework and to ensure realistic predictions of the flood risk (a key issue of the 2007/60/EU Directive) in ungauged basins, it is necessary to rethink the current engineering practices. In this vein, the collection of reliable hydrological data would be essential for re-evaluating the existing "recipes", taking into account local peculiarities, and for updating the modelling methodologies as needed.

The reliability paradox: Why robust cognitive tasks do not produce reliable individual differences.

Science.gov (United States)

Hedge, Craig; Powell, Georgina; Sumner, Petroc

2017-07-19

Individual differences in cognitive paradigms are increasingly employed to relate cognition to brain structure, chemistry, and function. However, such efforts are often unfruitful, even with the most well established tasks. Here we offer an explanation for failures in the application of robust cognitive paradigms to the study of individual differences. Experimental effects become well established - and thus those tasks become popular - when between-subject variability is low. However, low between-subject variability causes low reliability for individual differences, destroying replicable correlations with other factors and potentially undermining published conclusions drawn from correlational relationships. Though these statistical issues have a long history in psychology, they are widely overlooked in cognitive psychology and neuroscience today. In three studies, we assessed test-retest reliability of seven classic tasks: Eriksen Flanker, Stroop, stop-signal, go/no-go, Posner cueing, Navon, and Spatial-Numerical Association of Response Code (SNARC). Reliabilities ranged from 0 to .82, being surprisingly low for most tasks given their common use. As we predicted, this emerged from low variance between individuals rather than high measurement variance. In other words, the very reason such tasks produce robust and easily replicable experimental effects - low between-participant variability - makes their use as correlational tools problematic. We demonstrate that taking such reliability estimates into account has the potential to qualitatively change theoretical conclusions. The implications of our findings are that well-established approaches in experimental psychology and neuropsychology may not directly translate to the study of individual differences in brain structure, chemistry, and function, and alternative metrics may be required.

Predicting Flow Breakdown Probability and Duration in Stochastic Network Models: Impact on Travel Time Reliability

Energy Technology Data Exchange (ETDEWEB)

Dong, Jing [ORNL; Mahmassani, Hani S. [Northwestern University, Evanston

2011-01-01

This paper proposes a methodology to produce random flow breakdown endogenously in a mesoscopic operational model, by capturing breakdown probability and duration. Based on previous research findings that probability of flow breakdown can be represented as a function of flow rate and the duration can be characterized by a hazard model. By generating random flow breakdown at various levels and capturing the traffic characteristics at the onset of the breakdown, the stochastic network simulation model provides a tool for evaluating travel time variability. The proposed model can be used for (1) providing reliability related traveler information; (2) designing ITS (intelligent transportation systems) strategies to improve reliability; and (3) evaluating reliability-related performance measures of the system.

TFTR CAMAC power supplies reliability

International Nuclear Information System (INIS)

Camp, R.A.; Bergin, W.

1989-01-01

Since the expected life of the Tokamak Fusion Test Reactor (TFTR) has been extended into the early 1990's, the issues of equipment wear-out, when to refurbish/replace, and the costs associated with these decisions, must be faced. The management of the maintenance of the TFTR Central Instrumentation, Control and Data Acquisition System (CICADA) power supplies within the CAMAC network is a case study of a set of systems to monitor repairable systems reliability, costs, and results of action. The CAMAC network is composed of approximately 500 racks, each with its own power supply. By using a simple reliability estimator on a coarse time interval, in conjunction with determining the root cause of individual failures, a cost effective repair and maintenance program has been realized. This paper describes the estimator, some of the specific causes for recurring failures and their correction, and the subsequent effects on the reliability estimator. By extension of this program the authors can assess the continued viability of CAMAC power supplies into the future, predicting wear-out and developing cost effective refurbishment/replacement policies. 4 refs., 3 figs., 1 tab

Reliability-Based Decision Fusion in Multimodal Biometric Verification Systems

Directory of Open Access Journals (Sweden)

Kryszczuk Krzysztof

2007-01-01

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

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.

Computer Model to Estimate Reliability Engineering for Air Conditioning Systems

International Nuclear Information System (INIS)

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

2012-01-01

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

Medicine is not science: guessing the future, predicting the past.

Science.gov (United States)

Miller, Clifford

2014-12-01

Irregularity limits human ability to know, understand and predict. A better understanding of irregularity may improve the reliability of knowledge. Irregularity and its consequences for knowledge are considered. Reliable predictive empirical knowledge of the physical world has always been obtained by observation of regularities, without needing science or theory. Prediction from observational knowledge can remain reliable despite some theories based on it proving false. A naïve theory of irregularity is outlined. Reducing irregularity and/or increasing regularity can increase the reliability of knowledge. Beyond long experience and specialization, improvements include implementing supporting knowledge systems of libraries of appropriately classified prior cases and clinical histories and education about expertise, intuition and professional judgement. A consequence of irregularity and complexity is that classical reductionist science cannot provide reliable predictions of the behaviour of complex systems found in nature, including of the human body. Expertise, expert judgement and their exercise appear overarching. Diagnosis involves predicting the past will recur in the current patient applying expertise and intuition from knowledge and experience of previous cases and probabilistic medical theory. Treatment decisions are an educated guess about the future (prognosis). Benefits of the improvements suggested here are likely in fields where paucity of feedback for practitioners limits development of reliable expert diagnostic intuition. Further analysis, definition and classification of irregularity is appropriate. Observing and recording irregularities are initial steps in developing irregularity theory to improve the reliability and extent of knowledge, albeit some forms of irregularity present inherent difficulties. © 2014 John Wiley & Sons, Ltd.

Feasibility, Reliability and Predictive Value Of In-Ambulance Heart Rate Variability Registration

NARCIS (Netherlands)

Yperzeele, Laetitia; van Hooff, Robbert-Jan; De Smedt, Ann; Nagels, Guy; Hubloue, Ives; De Keyser, Jacques; Brouns, Raf

2016-01-01

Background Heart rate variability (HRV) is a parameter of autonomic nervous system function. A decrease of HRV has been associated with disease severity, risk of complications and prognosis in several conditions. Objective We aim to investigate the feasibility and the reliability of in-ambulance HRV

Improvement of the reliability on nondestructive inspection

International Nuclear Information System (INIS)

Song, Sung Jin; Kim, Young H.; Lee, Hyang Beom; Shin, Young Kil; Jung, Hyun Jo; Park, Ik Keun; Park, Eun Soo

2002-03-01

Retaining reliabilities of nondestructive testing is essential for the life-time maintenance of Nuclear Power Plant. The nondestructive testing methods which are frequently used in the Nuclear Power Plant are eddy current testing for the inspection of steam generator tubes and ultrasonic testing for the inspection of weldments. In order to improve reliabilities of ultrasonic testing and eddy current testing, the subjects carried out in this study are as follows : development of BEM analysis technique for ECT of SG tube, development of neural network technique for the intelligent analysis of ECT flaw signals of SG tubes, development of RFECT technology for the inspection of SG tube, FEM analysis of ultrasonic scattering field, evaluation of statistical reliability of PD-RR test of ultrasonic testing and development of multi-Gaussian beam modeling technique to predict accurate signal of signal beam ultrasonic testing with the efficiency in calculation time

Improvement of the reliability on nondestructive inspection

Energy Technology Data Exchange (ETDEWEB)

Song, Sung Jin; Kim, Young H. [Sungkyunkwan Univ., Suwon (Korea, Republic of); Lee, Hyang Beom [Soongsil Univ., Seoul (Korea, Republic of); Shin, Young Kil [Kunsan National Univ., Gunsan (Korea, Republic of); Jung, Hyun Jo [Wonkwang Univ., Iksan (Korea, Republic of); Park, Ik Keun; Park, Eun Soo [Seoul Nationl Univ., Seoul (Korea, Republic of)

2002-03-15

Retaining reliabilities of nondestructive testing is essential for the life-time maintenance of Nuclear Power Plant. The nondestructive testing methods which are frequently used in the Nuclear Power Plant are eddy current testing for the inspection of steam generator tubes and ultrasonic testing for the inspection of weldments. In order to improve reliabilities of ultrasonic testing and eddy current testing, the subjects carried out in this study are as follows : development of BEM analysis technique for ECT of SG tube, development of neural network technique for the intelligent analysis of ECT flaw signals of SG tubes, development of RFECT technology for the inspection of SG tube, FEM analysis of ultrasonic scattering field, evaluation of statistical reliability of PD-RR test of ultrasonic testing and development of multi-Gaussian beam modeling technique to predict accurate signal of signal beam ultrasonic testing with the efficiency in calculation time.

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

Elder abuse telephone screen reliability and validity.

Science.gov (United States)

Buri, Hilary M; Daly, Jeanette M; Jogerst, Gerald J

2009-01-01

(a) To identify reliable and valid questions that identify elder abuse, (b) to assess the reliability and validity of extant self-reported elder abuse screens in a high-risk elderly population, and (c) to describe difficulties of completing and interpreting screens in a high-need elderly population. All elders referred to research-trained social workers in a community service agency were asked to participate. Of the 70 elders asked, 49 participated, 44 completed the first questionnaire, and 32 completed the duplicate second questionnaire. A research assistant administered the telephone questionnaires. Twenty-nine (42%) persons were judged abused, 12 (17%) had abuse reported, and 4 (6%) had abuse substantiated. The elder abuse screen instruments were not found to be predictive of assessed abuse or as predictors of reported abuse; the measures tended toward being inversely predictive. Two questions regarding harm and taking of belongings were significantly different for the assessed abused group. In this small group of high-need community-dwelling elders, the screens were not effective in discriminating between abused and nonabused groups. Better instruments are needed to assess for elder abuse.

Assessing Internet addiction using the parsimonious Internet addiction components model - a preliminary study [forthcoming

OpenAIRE

Kuss, DJ; Shorter, GW; Van Rooij, AJ; Griffiths, MD; Schoenmakers, T

2014-01-01

Internet usage has grown exponentially over the last decade. Research indicates that excessive Internet use can lead to symptoms associated with addiction. To date, assessment of potential Internet addiction has varied regarding populations studied and instruments used, making reliable prevalence estimations difficult. To overcome the present problems a preliminary study was conducted testing a parsimonious Internet addiction components model based on Griffiths’ addiction components (2005), i...

Modular reliability modeling of the TJNAF personnel safety system

International Nuclear Information System (INIS)

Cinnamon, J.; Mahoney, K.

1997-01-01

A reliability model for the Thomas Jefferson National Accelerator Facility (formerly CEBAF) personnel safety system has been developed. The model, which was implemented using an Excel spreadsheet, allows simulation of all or parts of the system. Modularity os the model's implementation allows rapid open-quotes what if open-quotes case studies to simulate change in safety system parameters such as redundancy, diversity, and failure rates. Particular emphasis is given to the prediction of failure modes which would result in the failure of both of the redundant safety interlock systems. In addition to the calculation of the predicted reliability of the safety system, the model also calculates availability of the same system. Such calculations allow the user to make tradeoff studies between reliability and availability, and to target resources to improving those parts of the system which would most benefit from redesign or upgrade. The model includes calculated, manufacturer's data, and Jefferson Lab field data. This paper describes the model, methods used, and comparison of calculated to actual data for the Jefferson Lab personnel safety system. Examples are given to illustrate the model's utility and ease of use

Reliability evaluation of oil pipelines operating in aggressive environment

Science.gov (United States)

Magomedov, R. M.; Paizulaev, M. M.; Gebel, E. S.

2017-08-01

In connection with modern increased requirements for ecology and safety, the development of diagnostic services complex is obligatory and necessary enabling to ensure the reliable operation of the gas transportation infrastructure. Estimation of oil pipelines technical condition should be carried out not only to establish the current values of the equipment technological parameters in operation, but also to predict the dynamics of changes in the physical and mechanical characteristics of the material, the appearance of defects, etc. to ensure reliable and safe operation. In the paper, existing Russian and foreign methods for evaluation of the oil pipelines reliability are considered, taking into account one of the main factors leading to the appearance of crevice in the pipeline material, i.e. change the shape of its cross-section, - corrosion. Without compromising the generality of the reasoning, the assumption of uniform corrosion wear for the initial rectangular cross section has been made. As a result a formula for calculation the probability of failure-free operation was formulated. The proposed mathematical model makes it possible to predict emergency situations, as well as to determine optimal operating conditions for oil pipelines.

Value of CT to predict surgically important bowel and/or mesenteric injury in blunt trauma: performance of a preliminary scoring system

Energy Technology Data Exchange (ETDEWEB)

Faget, Claire; Taourel, Patrice; Ruyer, Alban; Alili, Chakib; Millet, Ingrid [CHU Lapeyronie, Department of Medical Imaging, Montpellier (France); Charbit, Jonathan [CHU Lapeyronie, Department of Intensive Care and Anesthesiology, Montpellier (France); Molinari, Nicolas [UMR 729 MISTEA, CHU Montpellier, Department of Medical Information and Statistics, Montpellier (France)

2015-12-15

To evaluate the performance of a computed tomography (CT) diagnostic score to predict surgical treatment for blunt bowel and/or mesentery injury (BBMI) in consecutive abdominal trauma. This was a retrospective observational study of 805 consecutive abdominal traumas with 556 patients included and screened by an abdominal radiologist blinded to the patient outcome, to evaluate numerous CT findings and calculate their diagnostic performances. These CT findings were compared using univariate and multivariate analysis between patients who had a laparotomy-confirmed BBMI requiring surgical repair, and those without BBMI requiring surgery. A CT score was obtained with an internal bootstrap validation. Fifty-six patients (10.1 %) had BBMI requiring surgery. Nine CT signs were independently associated with BBMI requiring surgery and were used to develop a CT diagnostic score. The AUC of our model was 0.98 (95 % CI 0.96-100), with a ≥5 cut-off. Its diagnostic performance was determined by internal validation: sensitivity 91.1-100 %, specificity 85.7-97.6 %, positive predictive value 41.4-82.3 % and negative predictive value 98.9-100 %. Bowel wall discontinuity and mesenteric pneumoperitoneum had the strongest association with BBMI requiring surgery (OR = 128.9 and 140.5, respectively). We developed a reliable CT scoring system which is easy to implement and highly predictive of BBMI requiring surgery. (orig.)

Preliminary Exploration of Encounter During Transit Across Southern Africa

Energy Technology Data Exchange (ETDEWEB)

Stroud, Phillip David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cuellar-Hengartner, Leticia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kubicek, Deborah Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cleland, Timothy James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-10-28

Los Alamos National Laboratory (LANL) is utilizing the Probability Effectiveness Methodology (PEM) tools, particularly the Pathway Analysis, Threat Response and Interdiction Options Tool (PATRIOT) to support the DNDO Architecture and Planning Directorate’s (APD) development of a multi-region terrorist risk assessment tool. The effort is divided into three stages. The first stage is an exploration of what can be done with PATRIOT essentially as is, to characterize encounter rate during transit across a single selected region. The second stage is to develop, condition, and implement required modifications to the data and conduct analysis to generate a well-founded assessment of the transit reliability across that selected region, and to identify any issues in the process. The final stage is to extend the work to a full multi-region global model. This document provides the results of the first stage, namely preliminary explorations with PATRIOT to assess the transit reliability across the region of southern Africa.

The Economics of Groundwater Replenishment for Reliable Urban Water Supply

Directory of Open Access Journals (Sweden)

Lei Gao

2014-06-01

Full Text Available This paper explores the potential economic benefits of water banking in aquifers to meet drought and emergency supplies for cities where the population is growing and changing climate has reduced the availability of water. A simplified case study based on the city of Perth, Australia was used to estimate the savings that could be achieved by water banking. Scenarios for investment in seawater desalination plants and groundwater replenishment were considered over a 20 year period of growing demand, using a Monte Carlo analysis that embedded the Markov model. An optimisation algorithm identified the minimum cost solutions that met specified criteria for supply reliability. The impact of depreciation of recharge credits was explored. The results revealed savings of more than A$1B (~US$1B or 37% to 33% of supply augmentation costs by including water banking in aquifers for 95% and 99.5% reliability of supply respectively. When the hypothetically assumed recharge credit depreciation rate was increased from 1% p.a. to 10% p.a. savings were still 33% to 31% for the same reliabilities. These preliminary results show that water banking in aquifers has potential to offer a highly attractive solution for efficiently increasing the security of urban water supplies where aquifers are suitable.

Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

Science.gov (United States)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2010-01-01

Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

Improving the reliability of female fertility breeding values using type and milk yield traits that predict energy status in Australian Holstein cattle.

Science.gov (United States)

González-Recio, O; Haile-Mariam, M; Pryce, J E

2016-01-01

The objectives of this study were (1) to propose changing the selection criteria trait for evaluating fertility in Australia from calving interval to conception rate at d 42 after the beginning of the mating season and (2) to use type traits as early fertility predictors, to increase the reliability of estimated breeding values for fertility. The breeding goal in Australia is conception within 6 wk of the start of the mating season. Currently, the Australian model to predict fertility breeding values (expressed as a linear transformation of calving interval) is a multitrait model that includes calving interval (CVI), lactation length (LL), calving to first service (CFS), first nonreturn rate (FNRR), and conception rate. However, CVI has a lower genetic correlation with the breeding goal (conception within 6 wk of the start of the mating season) than conception rate. Milk yield, type, and fertility data from 164,318 cow sired by 4,766 bulls were used. Principal component analysis and genetic correlation estimates between type and fertility traits were used to select type traits that could subsequently be used in a multitrait analysis. Angularity, foot angle, and pin set were chosen as type traits to include in an index with the traits that are included in the multitrait fertility model: CVI, LL, CFS, FNRR, and conception rate at d 42 (CR42). An index with these 8 traits is expected to achieve an average bull first proof reliability of 0.60 on the breeding objective (conception within 6 wk of the start of the mating season) compared with reliabilities of 0.39 and 0.45 for CR42 only or the current 5-trait Australian model. Subsequently, we used the first eigenvector of a principal component analysis with udder texture, bone quality, angularity, and body condition score to calculate an energy status indicator trait. The inclusion of the energy status indicator trait composite in a multitrait index with CVI, LL, CFS, FNRR, and CR42 achieved a 12-point increase in

Student Practice Evaluation Form-Revised Edition online comment bank: development and reliability analysis.

Science.gov (United States)

Rodger, Sylvia; Turpin, Merrill; Copley, Jodie; Coleman, Allison; Chien, Chi-Wen; Caine, Anne-Maree; Brown, Ted

2014-08-01

The reliable evaluation of occupational therapy students completing practice education placements along with provision of appropriate feedback is critical for both students and for universities from a quality assurance perspective. This study describes the development of a comment bank for use with an online version of the Student Practice Evaluation Form-Revised Edition (SPEF-R Online) and investigates its reliability. A preliminary bank of 109 individual comments (based on previous students' placement performance) was developed via five stages. These comments reflected all 11 SPEF-R domains. A purpose-designed online survey was used to examine the reliability of the comment bank. A total of 37 practice educators returned surveys, 31 of which were fully completed. Participants were asked to rate each individual comment using the five-point SPEF-R rating scale. One hundred and two of 109 comments demonstrated satisfactory agreement with their respective default ratings that were determined by the development team. At each domain level, the intra-class correlation coefficients (ranging between 0.86 and 0.96) also demonstrated good to excellent inter-rater reliability. There were only seven items that required rewording prior to inclusion in the final SPEF-R Online comment bank. The development of the SPEF-R Online comment bank offers a source of reliable comments (consistent with the SPEF-R rating scale across different domains) and aims to assist practice educators in providing reliable and timely feedback to students in a user-friendly manner. © 2014 Occupational Therapy Australia.

Re-establishing the pecking order: Niche models reliably predict suitable habitats for the reintroduction of red-billed oxpeckers.

Science.gov (United States)

Kalle, Riddhika; Combrink, Leigh; Ramesh, Tharmalingam; Downs, Colleen T

2017-03-01

Distributions of avian mutualists are affected by changes in biotic interactions and environmental conditions driven directly/indirectly by human actions. The range contraction of red-billed oxpeckers ( Buphagus erythrorhynchus ) in South Africa is partly a result of the widespread use of acaracides (i.e., mainly cattle dips), toxic to both ticks and oxpeckers. We predicted the habitat suitability of red-billed oxpeckers in South Africa using ensemble models to assist the ongoing reintroduction efforts and to identify new reintroduction sites for population recovery. The distribution of red-billed oxpeckers was influenced by moderate to high tree cover, woodland habitats, and starling density (a proxy for cavity-nesting birds) with regard to nest-site characteristics. Consumable resources (host and tick density), bioclimate, surface water body density, and proximity to protected areas were other influential predictors. Our models estimated 42,576.88-98,506.98 km 2 of highly suitable habitat (0.5-1) covering the majority of Limpopo, Mpumalanga, North West, a substantial portion of northern KwaZulu-Natal (KZN) and the Gauteng Province. Niche models reliably predicted suitable habitat in 40%-61% of the reintroduction sites where breeding is currently successful. Ensemble, boosted regression trees and generalized additive models predicted few suitable areas in the Eastern Cape and south of KZN that are part of the historic range. A few southern areas in the Northern Cape, outside the historic range, also had suitable sites predicted. Our models are a promising decision support tool for guiding reintroduction programs at macroscales. Apart from active reintroductions, conservation programs should encourage farmers and/or landowners to use oxpecker-compatible agrochemicals and set up adequate nest boxes to facilitate the population recovery of the red-billed oxpecker, particularly in human-modified landscapes. To ensure long-term conservation success, we suggest that

Reliability Models Applied to a System of Power Converters in Particle Accelerators

OpenAIRE

Siemaszko, D; Speiser, M; Pittet, S

2012-01-01

Several reliability models are studied when applied to a power system containing a large number of power converters. A methodology is proposed and illustrated in the case study of a novel linear particle accelerator designed for reaching high energies. The proposed methods result in the prediction of both reliability and availability of the considered system for optimisation purposes.

Reliability Analysis for Adhesive Bonded Composite Stepped Lap Joints Loaded in Fatigue

DEFF Research Database (Denmark)

Kimiaeifar, Amin; Sørensen, John Dalsgaard; Lund, Erik

2012-01-01

-1, where partial safety factors are introduced together with characteristic values. Asymptotic sampling is used to estimate the reliability with support points generated by randomized Sobol sequences. The predicted reliability level is compared with the implicitly required target reliability level defined......This paper describes a probabilistic approach to calculate the reliability of adhesive bonded composite stepped lap joints loaded in fatigue using three- dimensional finite element analysis (FEA). A method for progressive damage modelling is used to assess fatigue damage accumulation and residual...... by the wind turbine standard IEC 61400-1. Finally, an approach for the assessment of the reliability of adhesive bonded composite stepped lap joints loaded in fatigue is presented. The introduced methodology can be applied in the same way to calculate the reliability level of wind turbine blade components...

[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.

Climate Prediction Center - Monitoring & Data Index

Science.gov (United States)

Weather Service NWS logo - Click to go to the NWS home page Climate Prediction Center Site Map News Oceanic & Atmospheric Monitoring and Data Monitoring Weather & Climate in Realtime Climate Diagnostics Bulletin Preliminary Climate Diagnostics Bulletin Figures Monthly Atmospheric & Sea Surface

Reliability Evaluation for Clustered WSNs under Malware Propagation

Science.gov (United States)

Shen, Shigen; Huang, Longjun; Liu, Jianhua; Champion, Adam C.; Yu, Shui; Cao, Qiying

2016-01-01

We consider a clustered wireless sensor network (WSN) under epidemic-malware propagation conditions and solve the problem of how to evaluate its reliability so as to ensure efficient, continuous, and dependable transmission of sensed data from sensor nodes to the sink. Facing the contradiction between malware intention and continuous-time Markov chain (CTMC) randomness, we introduce a strategic game that can predict malware infection in order to model a successful infection as a CTMC state transition. Next, we devise a novel measure to compute the Mean Time to Failure (MTTF) of a sensor node, which represents the reliability of a sensor node continuously performing tasks such as sensing, transmitting, and fusing data. Since clustered WSNs can be regarded as parallel-serial-parallel systems, the reliability of a clustered WSN can be evaluated via classical reliability theory. Numerical results show the influence of parameters such as the true positive rate and the false positive rate on a sensor node’s MTTF. Furthermore, we validate the method of reliability evaluation for a clustered WSN according to the number of sensor nodes in a cluster, the number of clusters in a route, and the number of routes in the WSN. PMID:27294934

Reliability Evaluation for Clustered WSNs under Malware Propagation.

Science.gov (United States)

Shen, Shigen; Huang, Longjun; Liu, Jianhua; Champion, Adam C; Yu, Shui; Cao, Qiying

2016-06-10

We consider a clustered wireless sensor network (WSN) under epidemic-malware propagation conditions and solve the problem of how to evaluate its reliability so as to ensure efficient, continuous, and dependable transmission of sensed data from sensor nodes to the sink. Facing the contradiction between malware intention and continuous-time Markov chain (CTMC) randomness, we introduce a strategic game that can predict malware infection in order to model a successful infection as a CTMC state transition. Next, we devise a novel measure to compute the Mean Time to Failure (MTTF) of a sensor node, which represents the reliability of a sensor node continuously performing tasks such as sensing, transmitting, and fusing data. Since clustered WSNs can be regarded as parallel-serial-parallel systems, the reliability of a clustered WSN can be evaluated via classical reliability theory. Numerical results show the influence of parameters such as the true positive rate and the false positive rate on a sensor node's MTTF. Furthermore, we validate the method of reliability evaluation for a clustered WSN according to the number of sensor nodes in a cluster, the number of clusters in a route, and the number of routes in the WSN.

Influence Of Inspection Intervals On Mechanical System Reliability

International Nuclear Information System (INIS)

Zilberman, B.

1998-01-01

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

Acoustic signal emission monitoring as a novel method to predict steam pops during radiofrequency ablation: preliminary observations.

Science.gov (United States)

Chik, William W B; Kosobrodov, Roman; Bhaskaran, Abhishek; Barry, Michael Anthony Tony; Nguyen, Doan Trang; Pouliopoulos, Jim; Byth, Karen; Sivagangabalan, Gopal; Thomas, Stuart P; Ross, David L; McEwan, Alistair; Kovoor, Pramesh; Thiagalingam, Aravinda

2015-04-01

Steam pop is an explosive rupture of cardiac tissue caused by tissue overheating above 100 °C, resulting in steam formation, predisposing to serious complications associated with radiofrequency (RF) ablations. However, there are currently no reliable techniques to predict the occurrence of steam pops. We propose the utility of acoustic signals emitted during RF ablation as a novel method to predict steam pop formation and potentially prevent serious complications. Radiofrequency generator parameters (power, impedance, and temperature) were temporally recorded during ablations performed in an in vitro bovine myocardial model. The acoustic system consisted of HTI-96-min hydrophone, microphone preamplifier, and sound card connected to a laptop computer. The hydrophone has the frequency range of 2 Hz to 30 kHz and nominal sensitivity in the range -240 to -165 dB. The sound was sampled at 96 kHz with 24-bit resolution. Output signal from the hydrophone was fed into the camera audio input to synchronize the video stream. An automated system was developed for the detection and analysis of acoustic events. Nine steam pops were observed. Three distinct sounds were identified as warning signals, each indicating rapid steam formation and its release from tissue. These sounds had a broad frequency range up to 6 kHz with several spectral peaks around 2-3 kHz. Subjectively, these warning signals were perceived as separate loud clicks, a quick succession of clicks, or continuous squeaking noise. Characteristic acoustic signals were identified preceding 80% of pops occurrence. Six cardiologists were able to identify 65% of acoustic signals accurately preceding the pop. An automated system identified the characteristic warning signals in 85% of cases. The mean time from the first acoustic signal to pop occurrence was 46 ± 20 seconds. The automated system had 72.7% sensitivity and 88.9% specificity for predicting pops. Easily identifiable characteristic acoustic emissions

Reliability model for common mode failures in redundant safety systems

International Nuclear Information System (INIS)

Fleming, K.N.

1974-12-01

A method is presented for computing the reliability of redundant safety systems, considering both independent and common mode type failures. The model developed for the computation is a simple extension of classical reliability theory. The feasibility of the method is demonstrated with the use of an example. The probability of failure of a typical diesel-generator emergency power system is computed based on data obtained from U. S. diesel-generator operating experience. The results are compared with reliability predictions based on the assumption that all failures are independent. The comparison shows a significant increase in the probability of redundant system failure, when common failure modes are considered. (U.S.)

Space Shuttle Program Primary Avionics Software System (PASS) Success Legacy - Quality and Reliability Date

Science.gov (United States)

Orr, James K.; Peltier, Daryl

2010-01-01

Thsi slide presentation reviews the avionics software system on board the space shuttle, with particular emphasis on the quality and reliability. The Primary Avionics Software System (PASS) provides automatic and fly-by-wire control of critical shuttle systems which executes in redundant computers. Charts given show the number of space shuttle flights vs time, PASS's development history, and other charts that point to the reliability of the system's development. The reliability of the system is also compared to predicted reliability.

Materials and Reliability Handbook for Semiconductor Optical and Electron Devices

CERN Document Server

Pearton, Stephen

2013-01-01

Materials and Reliability Handbook for Semiconductor Optical and Electron Devices provides comprehensive coverage of reliability procedures and approaches for electron and photonic devices. These include lasers and high speed electronics used in cell phones, satellites, data transmission systems and displays. Lifetime predictions for compound semiconductor devices are notoriously inaccurate due to the absence of standard protocols. Manufacturers have relied on extrapolation back to room temperature of accelerated testing at elevated temperature. This technique fails for scaled, high current density devices. Device failure is driven by electric field or current mechanisms or low activation energy processes that are masked by other mechanisms at high temperature. The Handbook addresses reliability engineering for III-V devices, including materials and electrical characterization, reliability testing, and electronic characterization. These are used to develop new simulation technologies for device operation and ...

A SOFTWARE RELIABILITY ESTIMATION METHOD TO NUCLEAR SAFETY SOFTWARE

Directory of Open Access Journals (Sweden)

GEE-YONG PARK

2014-02-01

Full Text Available A method for estimating software reliability for nuclear safety software is proposed in this paper. This method is based on the software reliability growth model (SRGM, where the behavior of software failure is assumed to follow a non-homogeneous Poisson process. Two types of modeling schemes based on a particular underlying method are proposed in order to more precisely estimate and predict the number of software defects based on very rare software failure data. The Bayesian statistical inference is employed to estimate the model parameters by incorporating software test cases as a covariate into the model. It was identified that these models are capable of reasonably estimating the remaining number of software defects which directly affects the reactor trip functions. The software reliability might be estimated from these modeling equations, and one approach of obtaining software reliability value is proposed in this paper.

The quality improvement attitude survey: Development and preliminary psychometric characteristics.

Science.gov (United States)

Dunagan, Pamela B

2017-12-01

To report the development of a tool to measure nurse's attitudes about quality improvement in their practice setting and to examine preliminary psychometric characteristics of the Quality Improvement Nursing Attitude Scale. Human factors such as nursing attitudes of complacency have been identified as root causes of sentinel events. Attitudes of nurses concerning use of Quality and Safety Education for nurse's competencies can be most challenging to teach and to change. No tool has been developed measuring attitudes of nurses concerning their role in quality improvement. A descriptive study design with preliminary psychometric evaluation was used to examine the preliminary psychometric characteristics of the Quality Improvement Nursing Attitude Scale. Registered bedside clinical nurses comprised the sample for the study (n = 57). Quantitative data were analysed using descriptive statistics and Cronbach's alpha reliability. Total score and individual item statistics were evaluated. Two open-ended items were used to collect statements about nurses' feelings regarding their experience in quality improvement efforts. Strong support for the internal consistency reliability and face validity of the Quality Improvement Nursing Attitude Scale was found. Total scale scores were high indicating nurse participants valued Quality and Safety Education for Nurse competencies in practice. However, item-level statistics indicated nurses felt powerless when other nurses deviate from care standards. Additionally, the sample indicated they did not consistently report patient safety issues and did not have a feeling of value in efforts to improve care. Findings suggested organisational culture fosters nurses' reporting safety issues and feeling valued in efforts to improve care. Participants' narrative comments and item analysis revealed the need to generate new items for the Quality Improvement Nursing Attitude Scale focused on nurses' perception of their importance in quality and

Mission Reliability Estimation for Repairable Robot Teams

Science.gov (United States)

Trebi-Ollennu, Ashitey; Dolan, John; Stancliff, Stephen

2010-01-01

A mission reliability estimation method has been designed to translate mission requirements into choices of robot modules in order to configure a multi-robot team to have high reliability at minimal cost. In order to build cost-effective robot teams for long-term missions, one must be able to compare alternative design paradigms in a principled way by comparing the reliability of different robot models and robot team configurations. Core modules have been created including: a probabilistic module with reliability-cost characteristics, a method for combining the characteristics of multiple modules to determine an overall reliability-cost characteristic, and a method for the generation of legitimate module combinations based on mission specifications and the selection of the best of the resulting combinations from a cost-reliability standpoint. The developed methodology can be used to predict the probability of a mission being completed, given information about the components used to build the robots, as well as information about the mission tasks. In the research for this innovation, sample robot missions were examined and compared to the performance of robot teams with different numbers of robots and different numbers of spare components. Data that a mission designer would need was factored in, such as whether it would be better to have a spare robot versus an equivalent number of spare parts, or if mission cost can be reduced while maintaining reliability using spares. This analytical model was applied to an example robot mission, examining the cost-reliability tradeoffs among different team configurations. Particularly scrutinized were teams using either redundancy (spare robots) or repairability (spare components). Using conservative estimates of the cost-reliability relationship, results show that it is possible to significantly reduce the cost of a robotic mission by using cheaper, lower-reliability components and providing spares. This suggests that the

Test–retest reliability and construct validity of the Aspects of Wheelchair Mobility Test as a measure of the mobility of wheelchair users

Directory of Open Access Journals (Sweden)

Karen L. Rispin

2017-09-01

Conclusion: Results support the preliminary reliability and validity of the AWMT 2.0, supporting its effectiveness in comparing the mobility provided by different wheelchair types. This information can be used to enable effective use of limited funds for wheelchair selection at individual and organisational scales.

Predicting scholars' scientific impact.

Directory of Open Access Journals (Sweden)

Amin Mazloumian

Full Text Available We tested the underlying assumption that citation counts are reliable predictors of future success, analyzing complete citation data on the careers of ~150,000 scientists. Our results show that i among all citation indicators, the annual citations at the time of prediction is the best predictor of future citations, ii future citations of a scientist's published papers can be predicted accurately (r(2 = 0.80 for a 1-year prediction, P<0.001 but iii future citations of future work are hardly predictable.

Structural reliability analysis under evidence theory using the active learning kriging model

Science.gov (United States)

Yang, Xufeng; Liu, Yongshou; Ma, Panke

2017-11-01

Structural reliability analysis under evidence theory is investigated. It is rigorously proved that a surrogate model providing only correct sign prediction of the performance function can meet the accuracy requirement of evidence-theory-based reliability analysis. Accordingly, a method based on the active learning kriging model which only correctly predicts the sign of the performance function is proposed. Interval Monte Carlo simulation and a modified optimization method based on Karush-Kuhn-Tucker conditions are introduced to make the method more efficient in estimating the bounds of failure probability based on the kriging model. Four examples are investigated to demonstrate the efficiency and accuracy of the proposed method.

Predictive models applied to groundwater level forecasting: a preliminary experience on the alluvial aquifer of the Magra River (Italy).

Science.gov (United States)

Brozzo, Gianpiero; Doveri, Marco; Lelli, Matteo; Scozzari, Andrea

2010-05-01

Computer-based decision support systems are getting a growing interest for water managing authorities and water distribution companies. This work discusses a preliminary experience in the application of computational intelligence in a hydrological modeling framework, regarding the study area of the alluvial aquifer of the Magra River (Italy). Two sites in the studied area, corresponding to two distinct groups of wells (Battifollo and Fornola) are managed by the local drinkable water distribution company (ACAM Acque), which serves the area of La Spezia, on the Ligurian coast. Battifollo has 9 wells with a total extraction rate of about 240 liters per second, while Fornola has 44 wells with an extraction rate of about 900 liters per second. Objective of this work is to make use of time series coming from long-term monitoring activities in order to assess the trend of the groundwater level with respect to a set of environmental and exploitation parameters; this is accomplished by the experimentation of a suitable model, eligible to be used as a predictor. This activity moves on from the modeling of the system behavior, based on a set of Input/Output data, in order to characterize it without necessarily a prior knowledge of any deterministic mechanism (system identification). In this context, data series collected by continuous hydrological monitoring instrumentation installed in the studied sites, together with meteorological and water extraction data, have been analyzed in order to assess the applicability and performance of a predictive model of the groundwater level. A mixed approach (both data driven and process-based) has been experimented on the whole dataset relating to the last ten years of continuous monitoring activity. The system identification approach presented here is based on the integration of an adaptive technique based on Artificial Neural Networks (ANNs) and a blind deterministic identification approach. According to this concept, the behavior of

Study of complete interconnect reliability for a GaAs MMIC power amplifier

Science.gov (United States)

Lin, Qian; Wu, Haifeng; Chen, Shan-ji; Jia, Guoqing; Jiang, Wei; Chen, Chao

2018-05-01

By combining the finite element analysis (FEA) and artificial neural network (ANN) technique, the complete prediction of interconnect reliability for a monolithic microwave integrated circuit (MMIC) power amplifier (PA) at the both of direct current (DC) and alternating current (AC) operation conditions is achieved effectively in this article. As a example, a MMIC PA is modelled to study the electromigration failure of interconnect. This is the first time to study the interconnect reliability for an MMIC PA at the conditions of DC and AC operation simultaneously. By training the data from FEA, a high accuracy ANN model for PA reliability is constructed. Then, basing on the reliability database which is obtained from the ANN model, it can give important guidance for improving the reliability design for IC.

Novel Low Cost, High Reliability Wind Turbine Drivetrain

Energy Technology Data Exchange (ETDEWEB)

Chobot, Anthony; Das, Debarshi; Mayer, Tyler; Markey, Zach; Martinson, Tim; Reeve, Hayden; Attridge, Paul; El-Wardany, Tahany

2012-09-13

energy by 10.2%. This design was achieved by: (1) performing an extensive optimization study that deter-mined the preliminary cost for all practical chain drive topologies to ensure the most competitive configuration; (2) conducting detailed analysis of chain dynamics, contact stresses, and wear and efficiency characteristics over the chain's life to ensure accurate physics-based predictions of chain performance; and (3) developing a final product design, including reliability analysis, chain replacement procedures, and bearing and sprocket analysis. Definition of this final product configuration was used to develop refined cost of energy estimates. Finally, key system risks for the chain drive were defined and a comprehensive risk reduction plan was created for execution in Phase 2.

Transparent reliability model for fault-tolerant safety systems

International Nuclear Information System (INIS)

Bodsberg, Lars; Hokstad, Per

1997-01-01

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

Brain responses to biological motion predict treatment outcome in young adults with autism receiving Virtual Reality Social Cognition Training: Preliminary findings.

Science.gov (United States)

Yang, Y J Daniel; Allen, Tandra; Abdullahi, Sebiha M; Pelphrey, Kevin A; Volkmar, Fred R; Chapman, Sandra B

2017-06-01

Autism Spectrum Disorder (ASD) is characterized by remarkable heterogeneity in social, communication, and behavioral deficits, creating a major barrier in identifying effective treatments for a given individual with ASD. To facilitate precision medicine in ASD, we utilized a well-validated biological motion neuroimaging task to identify pretreatment biomarkers that can accurately forecast the response to an evidence-based behavioral treatment, Virtual Reality-Social Cognition Training (VR-SCT). In a preliminary sample of 17 young adults with high-functioning ASD, we identified neural predictors of change in emotion recognition after VR-SCT. The predictors were characterized by the pretreatment brain activations to biological vs. scrambled motion in the neural circuits that support (a) language comprehension and interpretation of incongruent auditory emotions and prosody, and (b) processing socio-emotional experience and interpersonal affective information, as well as emotional regulation. The predictive value of the findings for individual adults with ASD was supported by regression-based multivariate pattern analyses with cross validation. To our knowledge, this is the first pilot study that shows neuroimaging-based predictive biomarkers for treatment effectiveness in adults with ASD. The findings have potentially far-reaching implications for developing more precise and effective treatments for ASD. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

1988 failure rate screening data for fusion reliability and risk analysis

International Nuclear Information System (INIS)

Cadwallader, L.C.; Piet, S.J.

1988-01-01

This document contains failure rate screening data for application to fusion components. The screening values are generally fission or aerospace industry failure rate estimates that can be extrapolated for use by fusion system designers, reliability engineers and risk analysts. Failure rate estimates for tritium-bearing systems, liquid metal-cooled systems, gas-cooled systems, water-cooled systems and containment systems are given. Preliminary system availability estimates and selected initiating event frequency estimates are presented. This first edition document is valuable to design and safety analysis for the Compact Ignition Tokamak and the International Thermonuclear Experimental Reactor. 20 refs., 28 tabs