Increased Reliability for Single-Case Research Results: Is the Bootstrap the Answer?

ERIC Educational Resources Information Center

Parker, Richard I.

2006-01-01

There is need for objective and reliable single-case research (SCR) results in the movement toward evidence-based interventions (EBI), for inclusion in meta-analyses, and for funding accountability in clinical contexts. Yet SCR deals with data that often do not conform to parametric data assumptions and that yield results of low reliability. A…

Is One Trial Sufficient to Obtain Excellent Pressure Pain Threshold Reliability in the Low Back of Asymptomatic Individuals? A Test-Retest Study.

PubMed

Balaguier, Romain; Madeleine, Pascal; Vuillerme, Nicolas

2016-01-01

- and inter-session. Reliable measurements can be equally achieved when using the mean of two or three consecutive PPT measurements, as usually proposed in the literature, or with only the first one. Although reliability was almost perfect regardless of the conducted comparison between PPT assessments, our results suggest using two consecutive measurements to obtain higher short term absolute reliability.

SLAC modulator system improvements and reliability results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donaldson, A.R.

1998-06-01

In 1995, an improvement project was completed on the 244 klystron modulators in the linear accelerator. The modulator system has been previously described. This article offers project details and their resulting effect on modulator and component reliability. Prior to the project, the authors had collected four operating cycles (1991 through 1995) of MTTF data. In this discussion, the '91 data will be excluded since the modulators operated at 60 Hz. The five periods following the '91 run were reviewed due to the common repetition rate at 120 Hz.

Dental measurements and Bolton index reliability and accuracy obtained from 2D digital, 3D segmented CBCT, and 3d intraoral laser scanner

PubMed Central

San José, Verónica; Bellot-Arcís, Carlos; Tarazona, Beatriz; Zamora, Natalia; O Lagravère, Manuel

2017-01-01

Background To compare the reliability and accuracy of direct and indirect dental measurements derived from two types of 3D virtual models: generated by intraoral laser scanning (ILS) and segmented cone beam computed tomography (CBCT), comparing these with a 2D digital model. Material and Methods One hundred patients were selected. All patients’ records included initial plaster models, an intraoral scan and a CBCT. Patients´ dental arches were scanned with the iTero® intraoral scanner while the CBCTs were segmented to create three-dimensional models. To obtain 2D digital models, plaster models were scanned using a conventional 2D scanner. When digital models had been obtained using these three methods, direct dental measurements were measured and indirect measurements were calculated. Differences between methods were assessed by means of paired t-tests and regression models. Intra and inter-observer error were analyzed using Dahlberg´s d and coefficients of variation. Results Intraobserver and interobserver error for the ILS model was less than 0.44 mm while for segmented CBCT models, the error was less than 0.97 mm. ILS models provided statistically and clinically acceptable accuracy for all dental measurements, while CBCT models showed a tendency to underestimate measurements in the lower arch, although within the limits of clinical acceptability. Conclusions ILS and CBCT segmented models are both reliable and accurate for dental measurements. Integration of ILS with CBCT scans would get dental and skeletal information altogether. Key words:CBCT, intraoral laser scanner, 2D digital models, 3D models, dental measurements, reliability. PMID:29410764

Reproducibility and interoperator reliability of obtaining images and measurements of the cervix and uterus with brachytherapy treatment applicators in situ using transabdominal ultrasound.

PubMed

van Dyk, Sylvia; Garth, Margaret; Oates, Amanda; Kondalsamy-Chennakesavan, Srinivas; Schneider, Michal; Bernshaw, David; Narayan, Kailash

2016-01-01

To validate interoperator reliability of brachytherapy radiation therapists (RTs) in obtaining an ultrasound image and measuring the cervix and uterine dimensions using transabdominal ultrasound. Patients who underwent MRI with applicators in situ after the first insertion were included in the study. Imaging was performed by three RTs (RT1, RT2, and RT3) with varying degrees of ultrasound experience. All RTs were required to obtain a longitudinal planning image depicting the applicator in the uterine canal and measure the cervix and uterus. The MRI scan, taken 1 hour after the ultrasound, was used as the reference standard against which all measurements were compared. Measurements were analyzed with intraclass correlation coefficient and Bland-Altman plots. All RTs were able to obtain a suitable longitudinal image for each patient in the study. Mean differences (SD) between MRI and ultrasound measurements obtained by RTs ranged from 3.5 (3.6) to 4.4 (4.23) mm and 0 (3.0) to 0.9 (2.5) mm on the anterior and posterior surface of the cervix, respectively. Intraclass correlation coefficient for absolute agreement between MRI and RTs was >0.9 for all posterior measurement points in the cervix and ranged from 0.41 to 0.92 on the anterior surface. Measurements were not statistically different between RTs at any measurement point. RTs with variable training attained high levels of interoperator reliability when using transabdominal ultrasound to obtain images and measurements of the uterus and cervix with brachytherapy applicators in situ. Access to training and use of a well-defined protocol assist in achieving these high levels of reliability. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bucknor, Matthew; Grabaskas, David; Brunett, Acacia

2015-04-26

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

Reliability of environmental sampling culture results using the negative binomial intraclass correlation coefficient.

PubMed

Aly, Sharif S; Zhao, Jianyang; Li, Ben; Jiang, Jiming

2014-01-01

The Intraclass Correlation Coefficient (ICC) is commonly used to estimate the similarity between quantitative measures obtained from different sources. Overdispersed data is traditionally transformed so that linear mixed model (LMM) based ICC can be estimated. A common transformation used is the natural logarithm. The reliability of environmental sampling of fecal slurry on freestall pens has been estimated for Mycobacterium avium subsp. paratuberculosis using the natural logarithm transformed culture results. Recently, the negative binomial ICC was defined based on a generalized linear mixed model for negative binomial distributed data. The current study reports on the negative binomial ICC estimate which includes fixed effects using culture results of environmental samples. Simulations using a wide variety of inputs and negative binomial distribution parameters (r; p) showed better performance of the new negative binomial ICC compared to the ICC based on LMM even when negative binomial data was logarithm, and square root transformed. A second comparison that targeted a wider range of ICC values showed that the mean of estimated ICC closely approximated the true ICC.

The Americleft Speech Project: A Training and Reliability Study

PubMed Central

Chapman, Kathy L.; Baylis, Adriane; Trost-Cardamone, Judith; Cordero, Kelly Nett; Dixon, Angela; Dobbelsteyn, Cindy; Thurmes, Anna; Wilson, Kristina; Harding-Bell, Anne; Sweeney, Triona; Stoddard, Gregory; Sell, Debbie

2017-01-01

Objective To describe the results of two reliability studies and to assess the effect of training on interrater reliability scores. Design The first study (1) examined interrater and intrarater reliability scores (weighted and unweighted kappas) and (2) compared interrater reliability scores before and after training on the use of the Cleft Audit Protocol for Speech–Augmented (CAPS-A) with British English-speaking children. The second study examined interrater and intrarater reliability on a modified version of the CAPS-A (CAPS-A Americleft Modification) with American and Canadian English-speaking children. Finally, comparisons were made between the interrater and intrarater reliability scores obtained for Study 1 and Study 2. Participants The participants were speech-language pathologists from the Americleft Speech Project. Results In Study 1, interrater reliability scores improved for 6 of the 13 parameters following training on the CAPS-A protocol. Comparison of the reliability results for the two studies indicated lower scores for Study 2 compared with Study 1. However, this appeared to be an artifact of the kappa statistic that occurred due to insufficient variability in the reliability samples for Study 2. When percent agreement scores were also calculated, the ratings appeared similar across Study 1 and Study 2. Conclusion The findings of this study suggested that improvements in interrater reliability could be obtained following a program of systematic training. However, improvements were not uniform across all parameters. Acceptable levels of reliability were achieved for those parameters most important for evaluation of velopharyngeal function. PMID:25531738

The number of measurements needed to obtain high reliability for traits related to enzymatic activities and photosynthetic compounds in soybean plants infected with Phakopsora pachyrhizi.

PubMed

Oliveira, Tássia Boeno de; Azevedo Peixoto, Leonardo de; Teodoro, Paulo Eduardo; Alvarenga, Amauri Alves de; Bhering, Leonardo Lopes; Campo, Clara Beatriz Hoffmann

2018-01-01

Asian rust affects the physiology of soybean plants and causes losses in yield. Repeatability coefficients may help breeders to know how many measurements are needed to obtain a suitable reliability for a target trait. Therefore, the objectives of this study were to determine the repeatability coefficients of 14 traits in soybean plants inoculated with Phakopsora pachyrhizi and to establish the minimum number of measurements needed to predict the breeding value with high accuracy. Experiments were performed in a 3x2 factorial arrangement with three treatments and two inoculations in a random block design. Repeatability coefficients, coefficients of determination and number of measurements needed to obtain a certain reliability were estimated using ANOVA, principal component analysis based on the covariance matrix and the correlation matrix, structural analysis and mixed model. It was observed that the principal component analysis based on the covariance matrix out-performed other methods for almost all traits. Significant differences were observed for all traits except internal CO2 concentration for the treatment effects. For the measurement effects, all traits were significantly different. In addition, significant differences were found for all Treatment x Measurement interaction traits except coumestrol, chitinase and chlorophyll content. Six measurements were suitable to obtain a coefficient of determination higher than 0.7 for all traits based on principal component analysis. The information obtained from this research will help breeders and physiologists determine exactly how many measurements are needed to evaluate each trait in soybean plants infected by P. pachyrhizi with a desirable reliability.

The number of measurements needed to obtain high reliability for traits related to enzymatic activities and photosynthetic compounds in soybean plants infected with Phakopsora pachyrhizi

PubMed Central

de Oliveira, Tássia Boeno; Teodoro, Paulo Eduardo; de Alvarenga, Amauri Alves; Bhering, Leonardo Lopes; Campo, Clara Beatriz Hoffmann

2018-01-01

Asian rust affects the physiology of soybean plants and causes losses in yield. Repeatability coefficients may help breeders to know how many measurements are needed to obtain a suitable reliability for a target trait. Therefore, the objectives of this study were to determine the repeatability coefficients of 14 traits in soybean plants inoculated with Phakopsora pachyrhizi and to establish the minimum number of measurements needed to predict the breeding value with high accuracy. Experiments were performed in a 3x2 factorial arrangement with three treatments and two inoculations in a random block design. Repeatability coefficients, coefficients of determination and number of measurements needed to obtain a certain reliability were estimated using ANOVA, principal component analysis based on the covariance matrix and the correlation matrix, structural analysis and mixed model. It was observed that the principal component analysis based on the covariance matrix out-performed other methods for almost all traits. Significant differences were observed for all traits except internal CO2 concentration for the treatment effects. For the measurement effects, all traits were significantly different. In addition, significant differences were found for all Treatment x Measurement interaction traits except coumestrol, chitinase and chlorophyll content. Six measurements were suitable to obtain a coefficient of determination higher than 0.7 for all traits based on principal component analysis. The information obtained from this research will help breeders and physiologists determine exactly how many measurements are needed to evaluate each trait in soybean plants infected by P. pachyrhizi with a desirable reliability. PMID:29438380

The Americleft Speech Project: A Training and Reliability Study.

PubMed

Chapman, Kathy L; Baylis, Adriane; Trost-Cardamone, Judith; Cordero, Kelly Nett; Dixon, Angela; Dobbelsteyn, Cindy; Thurmes, Anna; Wilson, Kristina; Harding-Bell, Anne; Sweeney, Triona; Stoddard, Gregory; Sell, Debbie

2016-01-01

To describe the results of two reliability studies and to assess the effect of training on interrater reliability scores. The first study (1) examined interrater and intrarater reliability scores (weighted and unweighted kappas) and (2) compared interrater reliability scores before and after training on the use of the Cleft Audit Protocol for Speech-Augmented (CAPS-A) with British English-speaking children. The second study examined interrater and intrarater reliability on a modified version of the CAPS-A (CAPS-A Americleft Modification) with American and Canadian English-speaking children. Finally, comparisons were made between the interrater and intrarater reliability scores obtained for Study 1 and Study 2. The participants were speech-language pathologists from the Americleft Speech Project. In Study 1, interrater reliability scores improved for 6 of the 13 parameters following training on the CAPS-A protocol. Comparison of the reliability results for the two studies indicated lower scores for Study 2 compared with Study 1. However, this appeared to be an artifact of the kappa statistic that occurred due to insufficient variability in the reliability samples for Study 2. When percent agreement scores were also calculated, the ratings appeared similar across Study 1 and Study 2. The findings of this study suggested that improvements in interrater reliability could be obtained following a program of systematic training. However, improvements were not uniform across all parameters. Acceptable levels of reliability were achieved for those parameters most important for evaluation of velopharyngeal function.

Computing Reliabilities Of Ceramic Components Subject To Fracture

NASA Technical Reports Server (NTRS)

Nemeth, N. N.; Gyekenyesi, J. P.; Manderscheid, J. M.

1992-01-01

CARES calculates fast-fracture reliability or failure probability of macroscopically isotropic ceramic components. Program uses results from commercial structural-analysis program (MSC/NASTRAN or ANSYS) to evaluate reliability of component in presence of inherent surface- and/or volume-type flaws. Computes measure of reliability by use of finite-element mathematical model applicable to multiple materials in sense model made function of statistical characterizations of many ceramic materials. Reliability analysis uses element stress, temperature, area, and volume outputs, obtained from two-dimensional shell and three-dimensional solid isoparametric or axisymmetric finite elements. Written in FORTRAN 77.

Anatomical landmark position--can we trust what we see? Results from an online reliability and validity study of osteopaths.

PubMed

Pattyn, Elise; Rajendran, Dévan

2014-04-01

Practitioners traditionally use observation to classify the position of patients' anatomical landmarks. This information may contribute to diagnosis and patient management. To calculate a) Inter-rater reliability of categorising the sagittal plane position of four anatomical landmarks (lateral femoral epicondyle, greater trochanter, mastoid process and acromion) on side-view photographs (with landmarks highlighted and not-highlighted) of anonymised subjects; b) Intra-rater reliability; c) Individual landmark inter-rater reliability; d) Validity against a 'gold standard' photograph. Online inter- and intra-rater reliability study. Photographed subjects: convenience sample of asymptomatic students; raters: randomly selected UK registered osteopaths. 40 photographs of 30 subjects were used, a priori clinically acceptable reliability was ≥0.4. Inter-rater arm: 20 photographs without landmark highlights plus 10 with highlights; Intra-rater arm: 10 duplicate photographs (non-highlighted landmarks). Validity arm: highlighted landmark scores versus 'gold standard' photographs with vertical line. Research ethics approval obtained. Osteopaths (n = 48) categorised landmark position relative to imagined vertical-line; Gwet's Agreement Coefficient 1 (AC1) calculated and chance-corrected coefficient benchmarked against Landis and Koch's scale; Validity calculation used Kendall's tau-B. Inter-rater reliability was 'fair' (AC1 = 0.342; 95% confidence interval (CI) = 0.279-0.404) for non-highlighted landmarks and 'moderate' (AC1 = 0.700; 95% CI = 0.596-0.805) for highlighted landmarks. Intra-rater reliability was 'fair' (AC1 = 0.522); range was 'poor' (AC1 = 0.160) to 'substantial' (AC1 = 0.896). No differences were found between individual landmarks. Validity was 'low' (TB = 0.327; p = 0.104). Both inter- and intra-rater reliability was 'fair' but below clinically acceptable levels, validity was 'low'. Together these results challenge the clinical practice of

Reliable absolute analog code retrieval approach for 3D measurement

NASA Astrophysics Data System (ADS)

Yu, Shuang; Zhang, Jing; Yu, Xiaoyang; Sun, Xiaoming; Wu, Haibin; Chen, Deyun

2017-11-01

The wrapped phase of phase-shifting approach can be unwrapped by using Gray code, but both the wrapped phase error and Gray code decoding error can result in period jump error, which will lead to gross measurement error. Therefore, this paper presents a reliable absolute analog code retrieval approach. The combination of unequal-period Gray code and phase shifting patterns at high frequencies are used to obtain high-frequency absolute analog code, and at low frequencies, the same unequal-period combination patterns are used to obtain the low-frequency absolute analog code. Next, the difference between the two absolute analog codes was employed to eliminate period jump errors, and a reliable unwrapped result can be obtained. Error analysis was used to determine the applicable conditions, and this approach was verified through theoretical analysis. The proposed approach was further verified experimentally. Theoretical analysis and experimental results demonstrate that the proposed approach can perform reliable analog code unwrapping.

Reliability of reference distances used in photogrammetry.

PubMed

Aksu, Muge; Kaya, Demet; Kocadereli, Ilken

2010-07-01

To determine the reliability of the reference distances used for photogrammetric assessment. The sample consisted of 100 subjects with mean ages of 22.97 +/- 2.98 years. Five lateral and four frontal parameters were measured directly on the subjects' faces. For photogrammetric assessment, two reference distances for the profile view and three reference distances for the frontal view were established. Standardized photographs were taken and all the parameters that had been measured directly on the face were measured on the photographs. The reliability of the reference distances was checked by comparing direct and indirect values of the parameters obtained from the subjects' faces and photographs. Repeated measure analysis of variance (ANOVA) and Bland-Altman analyses were used for statistical assessment. For profile measurements, the indirect values measured were statistically different from the direct values except for Sn-Sto in male subjects and Prn-Sn and Sn-Sto in female subjects. The indirect values of Prn-Sn and Sn-Sto were reliable in both sexes. The poorest results were obtained in the indirect values of the N-Sn parameter for female subjects and the Sn-Me parameter for male subjects according to the Sa-Sba reference distance. For frontal measurements, the indirect values were statistically different from the direct values in both sexes except for one in male subjects. The indirect values measured were not statistically different from the direct values for Go-Go. The indirect values of Ch-Ch were reliable in male subjects. The poorest results were obtained according to the P-P reference distance. For profile assessment, the T-Ex reference distance was reliable for Prn-Sn and Sn-Sto in both sexes. For frontal assessment, Ex-Ex and En-En reference distances were reliable for Ch-Ch in male subjects.

Reliability Prediction Analysis: Airborne System Results and Best Practices

NASA Astrophysics Data System (ADS)

Silva, Nuno; Lopes, Rui

2013-09-01

This article presents the results of several reliability prediction analysis for aerospace components, made by both methodologies, the 217F and the 217Plus. Supporting and complementary activities are described, as well as the differences concerning the results and the applications of both methodologies that are summarized in a set of lessons learned that are very useful for RAMS and Safety Prediction practitioners.The effort that is required for these activities is also an important point that is discussed, as is the end result and their interpretation/impact on the system design.The article concludes while positioning these activities and methodologies in an overall process for space and aeronautics equipment/components certification, and highlighting their advantages. Some good practices have also been summarized and some reuse rules have been laid down.

Reliability Impacts in Life Support Architecture and Technology Selection

NASA Technical Reports Server (NTRS)

Lange Kevin E.; Anderson, Molly S.

2012-01-01

Quantitative assessments of system reliability and equivalent system mass (ESM) were made for different life support architectures based primarily on International Space Station technologies. The analysis was applied to a one-year deep-space mission. System reliability was increased by adding redundancy and spares, which added to the ESM. Results were thus obtained allowing a comparison of the ESM for each architecture at equivalent levels of reliability. Although the analysis contains numerous simplifications and uncertainties, the results suggest that achieving necessary reliabilities for deep-space missions will add substantially to the life support ESM and could influence the optimal degree of life support closure. Approaches for reducing reliability impacts were investigated and are discussed.

The LANDSAT system operated in Brazil by CNPq/INPE - results obtained in the area of mapping and future perspectives

NASA Technical Reports Server (NTRS)

Dejesusparada, N. (Principal Investigator); Barbosa, M. N.

1981-01-01

The LANDSAT system, operated in the country by CNPg/INPE since 1973, systematically acquires, produces, and distributes both multispectral and panchromatic images obtained through remote sensing satellites to thousands of researchers and technicians involved in the natural resources survey. To cooperate in the solution of national problems, CNPq/INPE is developing efforts in the area of manipulation of those images with the objective of making them useful as planimetric bases for the simple revision of already published maps or for its utilization as basic material in regions not yet reliability mapped. The results obtained from performed tests are presented and the existing limitations are discussed. The new system purchased to handle data from the next series of LANDSAT as well as from MAPSAT and SPOT which will be in operation within the 80's decade, and are designed not only for natural resources survey but also for the solution of cartographic problems.

Preliminary Results Obtained in Integrated Safety Analysis of NASA Aviation Safety Program Technologies

NASA Technical Reports Server (NTRS)

Reveley, Mary S.

2003-01-01

The goal of the NASA Aviation Safety Program (AvSP) is to develop and demonstrate technologies that contribute to a reduction in the aviation fatal accident rate by a factor of 5 by the year 2007 and by a factor of 10 by the year 2022. Integrated safety analysis of day-to-day operations and risks within those operations will provide an understanding of the Aviation Safety Program portfolio. Safety benefits analyses are currently being conducted. Preliminary results for the Synthetic Vision Systems (SVS) and Weather Accident Prevention (WxAP) projects of the AvSP have been completed by the Logistics Management Institute under a contract with the NASA Glenn Research Center. These analyses include both a reliability analysis and a computer simulation model. The integrated safety analysis method comprises two principal components: a reliability model and a simulation model. In the reliability model, the results indicate how different technologies and systems will perform in normal, degraded, and failed modes of operation. In the simulation, an operational scenario is modeled. The primary purpose of the SVS project is to improve safety by providing visual-flightlike situation awareness during instrument conditions. The current analyses are an estimate of the benefits of SVS in avoiding controlled flight into terrain. The scenario modeled has an aircraft flying directly toward a terrain feature. When the flight crew determines that the aircraft is headed toward an obstruction, the aircraft executes a level turn at speed. The simulation is ended when the aircraft completes the turn.

Reliability of fish size estimates obtained from multibeam imaging sonar

USGS Publications Warehouse

Hightower, Joseph E.; Magowan, Kevin J.; Brown, Lori M.; Fox, Dewayne A.

2013-01-01

Multibeam imaging sonars have considerable potential for use in fisheries surveys because the video-like images are easy to interpret, and they contain information about fish size, shape, and swimming behavior, as well as characteristics of occupied habitats. We examined images obtained using a dual-frequency identification sonar (DIDSON) multibeam sonar for Atlantic sturgeon Acipenser oxyrinchus oxyrinchus, striped bass Morone saxatilis, white perch M. americana, and channel catfish Ictalurus punctatus of known size (20–141 cm) to determine the reliability of length estimates. For ranges up to 11 m, percent measurement error (sonar estimate – total length)/total length × 100 varied by species but was not related to the fish's range or aspect angle (orientation relative to the sonar beam). Least-square mean percent error was significantly different from 0.0 for Atlantic sturgeon (x̄  =  −8.34, SE  =  2.39) and white perch (x̄  = 14.48, SE  =  3.99) but not striped bass (x̄  =  3.71, SE  =  2.58) or channel catfish (x̄  = 3.97, SE  =  5.16). Underestimating lengths of Atlantic sturgeon may be due to difficulty in detecting the snout or the longer dorsal lobe of the heterocercal tail. White perch was the smallest species tested, and it had the largest percent measurement errors (both positive and negative) and the lowest percentage of images classified as good or acceptable. Automated length estimates for the four species using Echoview software varied with position in the view-field. Estimates tended to be low at more extreme azimuthal angles (fish's angle off-axis within the view-field), but mean and maximum estimates were highly correlated with total length. Software estimates also were biased by fish images partially outside the view-field and when acoustic crosstalk occurred (when a fish perpendicular to the sonar and at relatively close range is detected in the side lobes of adjacent beams). These sources of

Assuring reliability program effectiveness.

NASA Technical Reports Server (NTRS)

Ball, L. W.

1973-01-01

An attempt is made to provide simple identification and description of techniques that have proved to be most useful either in developing a new product or in improving reliability of an established product. The first reliability task is obtaining and organizing parts failure rate data. Other tasks are parts screening, tabulation of general failure rates, preventive maintenance, prediction of new product reliability, and statistical demonstration of achieved reliability. Five principal tasks for improving reliability involve the physics of failure research, derating of internal stresses, control of external stresses, functional redundancy, and failure effects control. A final task is the training and motivation of reliability specialist engineers.

Overview of RICOR's reliability theoretical analysis, accelerated life demonstration test results and verification by field data

NASA Astrophysics Data System (ADS)

Vainshtein, Igor; Baruch, Shlomi; Regev, Itai; Segal, Victor; Filis, Avishai; Riabzev, Sergey

2018-05-01

The growing demand for EO applications that work around the clock 24hr/7days a week, such as in border surveillance systems, emphasizes the need for a highly reliable cryocooler having increased operational availability and optimized system's Integrated Logistic Support (ILS). In order to meet this need, RICOR developed linear and rotary cryocoolers which achieved successfully this goal. Cryocoolers MTTF was analyzed by theoretical reliability evaluation methods, demonstrated by normal and accelerated life tests at Cryocooler level and finally verified by field data analysis derived from Cryocoolers operating at system level. The following paper reviews theoretical reliability analysis methods together with analyzing reliability test results derived from standard and accelerated life demonstration tests performed at Ricor's advanced reliability laboratory. As a summary for the work process, reliability verification data will be presented as a feedback from fielded systems.

Biopsy Specimens Obtained 7 Days After Starting Chemoradiotherapy (CRT) Provide Reliable Predictors of Response to CRT for Rectal Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Toshiyuki; Sadahiro, Sotaro, E-mail: sadahiro@is.icc.u-tokai.ac.jp; Tanaka, Akira

2013-04-01

Purpose: Preoperative chemoradiation therapy (CRT) significantly decreases local recurrence in locally advanced rectal cancer. Various biomarkers in biopsy specimens obtained before CRT have been proposed as predictors of response. However, reliable biomarkers remain to be established. Methods and Materials: The study group comprised 101 consecutive patients with locally advanced rectal cancer who received preoperative CRT with oral uracil/tegafur (UFT) or S-1. We evaluated histologic findings on hematoxylin and eosin (H and E) staining and immunohistochemical expressions of Ki67, p53, p21, and apoptosis in biopsy specimens obtained before CRT and 7 days after starting CRT. These findings were contrasted with themore » histologic response and the degree of tumor shrinkage. Results: In biopsy specimens obtained before CRT, histologic marked regression according to the Japanese Classification of Colorectal Carcinoma (JCCC) criteria and the degree of tumor shrinkage on barium enema examination (BE) were significantly greater in patients with p21-positive tumors than in those with p21-negative tumors (P=.04 and P<.01, respectively). In biopsy specimens obtained 7 days after starting CRT, pathologic complete response, histologic marked regression according to both the tumor regression criteria and JCCC criteria, and T downstaging were significantly greater in patients with apoptosis-positive and p21-positive tumors than in those with apoptosis-negative (P<.01, P=.02, P=.01, and P<.01, respectively) or p21-negative tumors (P=.03, P<.01, P<.01, and P=.02, respectively). The degree of tumor shrinkage on both BE as well as MRI was significantly greater in patients with apoptosis-positive and with p21-positive tumors than in those with apoptosis-negative or p21-negative tumors, respectively. Histologic changes in H and E-stained biopsy specimens 7 days after starting CRT significantly correlated with pathologic complete response and marked regression on both JCCC and tumor

Design features and results from fatigue reliability research machines.

NASA Technical Reports Server (NTRS)

Lalli, V. R.; Kececioglu, D.; Mcconnell, J. B.

1971-01-01

The design, fabrication, development, operation, calibration and results from reversed bending combined with steady torque fatigue research machines are presented. Fifteen-centimeter long, notched, SAE 4340 steel specimens are subjected to various combinations of these stresses and cycled to failure. Failure occurs when the crack in the notch passes through the specimen automatically shutting down the test machine. These cycles-to-failure data are statistically analyzed to develop a probabilistic S-N diagram. These diagrams have many uses; a rotating component design example given in the literature shows that minimum size and weight for a specified number of cycles and reliability can be calculated using these diagrams.

General Aviation Aircraft Reliability Study

NASA Technical Reports Server (NTRS)

Pettit, Duane; Turnbull, Andrew; Roelant, Henk A. (Technical Monitor)

2001-01-01

This reliability study was performed in order to provide the aviation community with an estimate of Complex General Aviation (GA) Aircraft System reliability. To successfully improve the safety and reliability for the next generation of GA aircraft, a study of current GA aircraft attributes was prudent. This was accomplished by benchmarking the reliability of operational Complex GA Aircraft Systems. Specifically, Complex GA Aircraft System reliability was estimated using data obtained from the logbooks of a random sample of the Complex GA Aircraft population.

Comparison of Anaerobic Susceptibility Results Obtained by Different Methods

PubMed Central

Rosenblatt, J. E.; Murray, P. R.; Sonnenwirth, A. C.; Joyce, J. L.

1979-01-01

Susceptibility tests using 7 antimicrobial agents (carbenicillin, chloramphenicol, clindamycin, penicillin, cephalothin, metronidazole, and tetracycline) were run against 35 anaerobes including Bacteroides fragilis (17), other gram-negative bacilli (7), clostridia (5), peptococci (4), and eubacteria (2). Results in triplicate obtained by the microbroth dilution method and the aerobic modification of the broth disk method were compared with those obtained with an agar dilution method using Wilkins-Chalgren agar. Media used in the microbroth dilution method included Wilkins-Chalgren broth, brain heart infusion broth, brucella broth, tryptic soy broth, thioglycolate broth, and Schaedler's broth. A result differing by more than one dilution from the Wilkins-Chalgren agar result was considered a discrepancy, and when there was a change in susceptibility status this was termed a significant discrepancy. The microbroth dilution method using Wilkins-Chalgren broth and thioglycolate broth produced the fewest total discrepancies (22 and 24, respectively), and Wilkins-Chalgren broth, thioglycolate, and Schaedler's broth had the fewest significant discrepancies (6, 5, and 5, respectively). With the broth disk method, there were 15 significant discrepancies, although half of these were with tetracycline, which was the antimicrobial agent associated with the highest number of significant discrepancies (33), considering all of the test methods and media. PMID:464560

A comparison of manual anthropometric measurements with Kinect-based scanned measurements in terms of precision and reliability.

PubMed

Bragança, Sara; Arezes, Pedro; Carvalho, Miguel; Ashdown, Susan P; Castellucci, Ignacio; Leão, Celina

2018-01-01

Collecting anthropometric data for real-life applications demands a high degree of precision and reliability. It is important to test new equipment that will be used for data collectionOBJECTIVE:Compare two anthropometric data gathering techniques - manual methods and a Kinect-based 3D body scanner - to understand which of them gives more precise and reliable results. The data was collected using a measuring tape and a Kinect-based 3D body scanner. It was evaluated in terms of precision by considering the regular and relative Technical Error of Measurement and in terms of reliability by using the Intraclass Correlation Coefficient, Reliability Coefficient, Standard Error of Measurement and Coefficient of Variation. The results obtained showed that both methods presented better results for reliability than for precision. Both methods showed relatively good results for these two variables, however, manual methods had better results for some body measurements. Despite being considered sufficiently precise and reliable for certain applications (e.g. apparel industry), the 3D scanner tested showed, for almost every anthropometric measurement, a different result than the manual technique. Many companies design their products based on data obtained from 3D scanners, hence, understanding the precision and reliability of the equipment used is essential to obtain feasible results.

Reliability, Durability, and Safety | Transportation Research | NREL

Science.gov Websites

fill results obtained in different scenarios. The animation serves as a useful tool to help fleet limitations from a performance and reliability perspective. Evaluation results for three different BIMs analysis assists in development and helps end users select and deploy appropriate sensors for different

The reliable solution and computation time of variable parameters logistic model

NASA Astrophysics Data System (ADS)

Wang, Pengfei; Pan, Xinnong

2018-05-01

The study investigates the reliable computation time (RCT, termed as T c) by applying a double-precision computation of a variable parameters logistic map (VPLM). Firstly, by using the proposed method, we obtain the reliable solutions for the logistic map. Secondly, we construct 10,000 samples of reliable experiments from a time-dependent non-stationary parameters VPLM and then calculate the mean T c. The results indicate that, for each different initial value, the T cs of the VPLM are generally different. However, the mean T c trends to a constant value when the sample number is large enough. The maximum, minimum, and probable distribution functions of T c are also obtained, which can help us to identify the robustness of applying a nonlinear time series theory to forecasting by using the VPLM output. In addition, the T c of the fixed parameter experiments of the logistic map is obtained, and the results suggest that this T c matches the theoretical formula-predicted value.

Reliability-based structural optimization: A proposed analytical-experimental study

NASA Technical Reports Server (NTRS)

Stroud, W. Jefferson; Nikolaidis, Efstratios

1993-01-01

An analytical and experimental study for assessing the potential of reliability-based structural optimization is proposed and described. In the study, competing designs obtained by deterministic and reliability-based optimization are compared. The experimental portion of the study is practical because the structure selected is a modular, actively and passively controlled truss that consists of many identical members, and because the competing designs are compared in terms of their dynamic performance and are not destroyed if failure occurs. The analytical portion of this study is illustrated on a 10-bar truss example. In the illustrative example, it is shown that reliability-based optimization can yield a design that is superior to an alternative design obtained by deterministic optimization. These analytical results provide motivation for the proposed study, which is underway.

Pre-analytical and analytical aspects affecting clinical reliability of plasma glucose results.

PubMed

Pasqualetti, Sara; Braga, Federica; Panteghini, Mauro

2017-07-01

The measurement of plasma glucose (PG) plays a central role in recognizing disturbances in carbohydrate metabolism, with established decision limits that are globally accepted. This requires that PG results are reliable and unequivocally valid no matter where they are obtained. To control the pre-analytical variability of PG and prevent in vitro glycolysis, the use of citrate as rapidly effective glycolysis inhibitor has been proposed. However, the commercial availability of several tubes with studies showing different performance has created confusion among users. Moreover, and more importantly, studies have shown that tubes promptly inhibiting glycolysis give PG results that are significantly higher than tubes containing sodium fluoride only, used in the majority of studies generating the current PG cut-points, with a different clinical classification of subjects. From the analytical point of view, to be equivalent among different measuring systems, PG results should be traceable to a recognized higher-order reference via the implementation of an unbroken metrological hierarchy. In doing this, it is important that manufacturers of measuring systems consider the uncertainty accumulated through the different steps of the selected traceability chain. In particular, PG results should fulfil analytical performance specifications defined to fit the intended clinical application. Since PG has tight homeostatic control, its biological variability may be used to define these limits. Alternatively, given the central diagnostic role of the analyte, an outcome model showing the impact of analytical performance of test on clinical classifications of subjects can be used. Using these specifications, performance assessment studies employing commutable control materials with values assigned by reference procedure have shown that the quality of PG measurements is often far from desirable and that problems are exacerbated using point-of-care devices. Copyright © 2017 The Canadian

Reliability Assessment of a Robust Design Under Uncertainty for a 3-D Flexible Wing

NASA Technical Reports Server (NTRS)

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

2003-01-01

The paper presents reliability assessment results for the robust designs under uncertainty of a 3-D flexible wing previously reported by the authors. Reliability assessments (additional optimization problems) of the active constraints at the various probabilistic robust design points are obtained and compared with the constraint values or target constraint probabilities specified in the robust design. In addition, reliability-based sensitivity derivatives with respect to design variable mean values are also obtained and shown to agree with finite difference values. These derivatives allow one to perform reliability based design without having to obtain second-order sensitivity derivatives. However, an inner-loop optimization problem must be solved for each active constraint to find the most probable point on that constraint failure surface.

[Reliability for detection of developmental problems using the semaphore from the Child Development Evaluation test: Is a yellow result different from a red result?

PubMed

Rizzoli-Córdoba, Antonio; Ortega-Ríosvelasco, Fernando; Villasís-Keever, Miguel Ángel; Pizarro-Castellanos, Mariel; Buenrostro-Márquez, Guillermo; Aceves-Villagrán, Daniel; O'Shea-Cuevas, Gabriel; Muñoz-Hernández, Onofre

The Child Development Evaluation (CDE) is a screening tool designed and validated in Mexico for detecting developmental problems. The result is expressed through a semaphore. In the CDE test, both yellow and red results are considered positive, although a different intervention is proposed for each. The aim of this work was to evaluate the reliability of the CDE test to discriminate between children with yellow/red result based on the developmental domain quotient (DDQ) obtained through the Battelle Development Inventory, 2nd edition (in Spanish) (BDI-2). The information was obtained for the study from the validation. Children with a normal (green) result in the CDE were excluded. Two different cut-off points of the DDQ were used (BDI-2): <90 to include low average, and developmental delay was considered with a cut-off<80 per domain. Results were analyzed based on the correlation of the CDE test and each domain from the BDI-2 and by subgroups of age. With a cut-off DDQ<90, 86.8% of tests with yellow result (CDE) indicated at least one domain affected and 50% 3 or more compared with 93.8% and 78.8% for red result, respectively. There were differences in every domain (P<0.001) for the percent of children with DDQ<80 between yellow and red result (CDE): cognitive 36.1% vs. 61.9%; communication: 27.8% vs. 50.4%, motor: 18.1% vs. 39.9%; personal-social: 20.1% vs. 28.9%; and adaptive: 6.9% vs. 20.4%. The semaphore result yellow/red allows identifying different magnitudes of delay in developmental domains or subdomains, supporting the recommendation of different interventions for each one. Copyright © 2014 Hospital Infantil de México Federico Gómez. Publicado por Masson Doyma México S.A. All rights reserved.

Validity and reliability of the Diagnostic Adaptive Behaviour Scale.

PubMed

Tassé, M J; Schalock, R L; Balboni, G; Spreat, S; Navas, P

2016-01-01

The Diagnostic Adaptive Behaviour Scale (DABS) is a new standardised adaptive behaviour measure that provides information for evaluating limitations in adaptive behaviour for the purpose of determining a diagnosis of intellectual disability. This article presents validity evidence and reliability data for the DABS. Validity evidence was based on comparing DABS scores with scores obtained on the Vineland Adaptive Behaviour Scale, second edition. The stability of the test scores was measured using a test and retest, and inter-rater reliability was assessed by computing the inter-respondent concordance. The DABS convergent validity coefficients ranged from 0.70 to 0.84, while the test-retest reliability coefficients ranged from 0.78 to 0.95, and the inter-rater concordance as measured by intraclass correlation coefficients ranged from 0.61 to 0.87. All obtained validity and reliability indicators were strong and comparable with the validity and reliability coefficients of the most commonly used adaptive behaviour instruments. These results and the advantages of the DABS for clinician and researcher use are discussed. © 2015 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Evaluating North American Electric Grid Reliability Using the Barabasi-Albert Network Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chassin, David P.; Posse, Christian

2005-09-15

The reliability of electric transmission systems is examined using a scale-free model of network topology and failure propagation. The topologies of the North American eastern and western electric grids are analyzed to estimate their reliability based on the Barabási-Albert network model. A commonly used power system reliability index is computed using a simple failure propagation model. The results are compared to the values of power system reliability indices previously obtained using other methods and they suggest that scale-free network models are usable to estimate aggregate electric grid reliability.

Evaluating North American Electric Grid Reliability Using the Barabasi-Albert Network Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chassin, David P.; Posse, Christian

2005-09-15

The reliability of electric transmission systems is examined using a scale-free model of network topology and failure propagation. The topologies of the North American eastern and western electric grids are analyzed to estimate their reliability based on the Barabasi-Albert network model. A commonly used power system reliability index is computed using a simple failure propagation model. The results are compared to the values of power system reliability indices previously obtained using standard power engineering methods, and they suggest that scale-free network models are usable to estimate aggregate electric grid reliability.

Approximation of reliabilities for multiple-trait model with maternal effects.

PubMed

Strabel, T; Misztal, I; Bertrand, J K

2001-04-01

Reliabilities for a multiple-trait maternal model were obtained by combining reliabilities obtained from single-trait models. Single-trait reliabilities were obtained using an approximation that supported models with additive and permanent environmental effects. For the direct effect, the maternal and permanent environmental variances were assigned to the residual. For the maternal effect, variance of the direct effect was assigned to the residual. Data included 10,550 birth weight, 11,819 weaning weight, and 3,617 postweaning gain records of Senepol cattle. Reliabilities were obtained by generalized inversion and by using single-trait and multiple-trait approximation methods. Some reliabilities obtained by inversion were negative because inbreeding was ignored in calculating the inverse of the relationship matrix. The multiple-trait approximation method reduced the bias of approximation when compared with the single-trait method. The correlations between reliabilities obtained by inversion and by multiple-trait procedures for the direct effect were 0.85 for birth weight, 0.94 for weaning weight, and 0.96 for postweaning gain. Correlations for maternal effects for birth weight and weaning weight were 0.96 to 0.98 for both approximations. Further improvements can be achieved by refining the single-trait procedures.

Modeling Sensor Reliability in Fault Diagnosis Based on Evidence Theory

PubMed Central

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

2016-01-01

Sensor data fusion plays an important role in fault diagnosis. Dempster–Shafer (D-R) evidence theory is widely used in fault diagnosis, since it is efficient to combine evidence from different sensors. However, under the situation where the evidence highly conflicts, it may obtain a counterintuitive result. To address the issue, a new method is proposed in this paper. Not only the statistic sensor reliability, but also the dynamic sensor reliability are taken into consideration. The evidence distance function and the belief entropy are combined to obtain the dynamic reliability of each sensor report. A weighted averaging method is adopted to modify the conflict evidence by assigning different weights to evidence according to sensor reliability. The proposed method has better performance in conflict management and fault diagnosis due to the fact that the information volume of each sensor report is taken into consideration. An application in fault diagnosis based on sensor fusion is illustrated to show the efficiency of the proposed method. The results show that the proposed method improves the accuracy of fault diagnosis from 81.19% to 89.48% compared to the existing methods. PMID:26797611

Validity and Reliability of a Systematic Database Search Strategy to Identify Publications Resulting From Pharmacy Residency Research Projects.

PubMed

Kwak, Namhee; Swan, Joshua T; Thompson-Moore, Nathaniel; Liebl, Michael G

2016-08-01

This study aims to develop a systematic search strategy and test its validity and reliability in terms of identifying projects published in peer-reviewed journals as reported by residency graduates through an online survey. This study was a prospective blind comparison to a reference standard. Pharmacy residency projects conducted at the study institution between 2001 and 2012 were included. A step-wise, systematic procedure containing up to 8 search strategies in PubMed and EMBASE for each project was created using the names of authors and abstract keywords. In order to further maximize sensitivity, complex phrases with multiple variations were truncated to the root word. Validity was assessed by obtaining information on publications from an online survey deployed to residency graduates. The search strategy identified 13 publications (93% sensitivity, 100% specificity, and 99% accuracy). Both methods identified a similar proportion achieving publication (19.7% search strategy vs 21.2% survey, P = 1.00). Reliability of the search strategy was affirmed by the perfect agreement between 2 investigators (k = 1.00). This systematic search strategy demonstrated a high sensitivity, specificity, and accuracy for identifying publications resulting from pharmacy residency projects using information available in residency conference abstracts. © The Author(s) 2015.

Reliability Impacts in Life Support Architecture and Technology Selection

NASA Technical Reports Server (NTRS)

Lange, Kevin E.; Anderson, Molly S.

2011-01-01

Equivalent System Mass (ESM) and reliability estimates were performed for different life support architectures based primarily on International Space Station (ISS) technologies. The analysis was applied to a hypothetical 1-year deep-space mission. High-level fault trees were initially developed relating loss of life support functionality to the Loss of Crew (LOC) top event. System reliability was then expressed as the complement (nonoccurrence) this event and was increased through the addition of redundancy and spares, which added to the ESM. The reliability analysis assumed constant failure rates and used current projected values of the Mean Time Between Failures (MTBF) from an ISS database where available. Results were obtained showing the dependence of ESM on system reliability for each architecture. Although the analysis employed numerous simplifications and many of the input parameters are considered to have high uncertainty, the results strongly suggest that achieving necessary reliabilities for deep-space missions will add substantially to the life support system mass. As a point of reference, the reliability for a single-string architecture using the most regenerative combination of ISS technologies without unscheduled replacement spares was estimated to be less than 1%. The results also demonstrate how adding technologies in a serial manner to increase system closure forces the reliability of other life support technologies to increase in order to meet the system reliability requirement. This increase in reliability results in increased mass for multiple technologies through the need for additional spares. Alternative parallel architecture approaches and approaches with the potential to do more with less are discussed. The tall poles in life support ESM are also reexamined in light of estimated reliability impacts.

Ceramic material life prediction: A program to translate ANSYS results to CARES/LIFE reliability analysis

NASA Technical Reports Server (NTRS)

Vonhermann, Pieter; Pintz, Adam

1994-01-01

This manual describes the use of the ANSCARES program to prepare a neutral file of FEM stress results taken from ANSYS Release 5.0, in the format needed by CARES/LIFE ceramics reliability program. It is intended for use by experienced users of ANSYS and CARES. Knowledge of compiling and linking FORTRAN programs is also required. Maximum use is made of existing routines (from other CARES interface programs and ANSYS routines) to extract the finite element results and prepare the neutral file for input to the reliability analysis. FORTRAN and machine language routines as described are used to read the ANSYS results file. Sub-element stresses are computed and written to a neutral file using FORTRAN subroutines which are nearly identical to those used in the NASCARES (MSC/NASTRAN to CARES) interface.

Interrelation Between Safety Factors and Reliability

NASA Technical Reports Server (NTRS)

Elishakoff, Isaac; Chamis, Christos C. (Technical Monitor)

2001-01-01

An evaluation was performed to establish relationships between safety factors and reliability relationships. Results obtained show that the use of the safety factor is not contradictory to the employment of the probabilistic methods. In many cases the safety factors can be directly expressed by the required reliability levels. However, there is a major difference that must be emphasized: whereas the safety factors are allocated in an ad hoc manner, the probabilistic approach offers a unified mathematical framework. The establishment of the interrelation between the concepts opens an avenue to specify safety factors based on reliability. In cases where there are several forms of failure, then the allocation of safety factors should he based on having the same reliability associated with each failure mode. This immediately suggests that by the probabilistic methods the existing over-design or under-design can be eliminated. The report includes three parts: Part 1-Random Actual Stress and Deterministic Yield Stress; Part 2-Deterministic Actual Stress and Random Yield Stress; Part 3-Both Actual Stress and Yield Stress Are Random.

Validation of Observations Obtained with a Liquid Mirror Telescope by Comparison with Sloan Digital Sky Survey Observations

NASA Astrophysics Data System (ADS)

Borra, E. F.

2015-06-01

The results of a search for peculiar astronomical objects using very low resolution spectra obtained with the NASA Orbital Debris Observatory (NODO) 3 m diameter liquid mirror telescope (LMT) are compared with results of spectra obtained with the Sloan Digital Sky Survey (SDSS). The main purpose of this comparison is to verify whether observations taken with this novel type of telescope are reliable. This comparison is important because LMTs are an inexpensive novel type of telescope that is very useful for astronomical surveys, particularly surveys in the time domain, and validation of the data taken with an LMT by comparison with data from a classical telescope will validate their reliability. We start from a published data analysis that classified as peculiar only 206 of the 18,000 astronomical objects observed with the NODO LMT. A total of 29 of these 206 objects were found in the SDSS. The reliability of the NODO data can be seen through the results of the detailed analysis that, in practice, incorrectly identified less than 0.3% of the 18,000 spectra as peculiar objects, most likely because they are variable stars. We conclude that the LMT gave reliable observations, comparable to those that would have been obtained with a telescope using a glass mirror.

Circumferential finger measurements utilizing a torque meter to increase reliability.

PubMed

King, T I

1993-01-01

The purpose of this study was to compare the reliabilities of two methods of measuring finger circumference. Traditionally, finger circumference is determined clinically by the use of a tape measure. In this study, a tape-measure device for recording finger circumference utilizing a torque meter was compared with the traditional method to determine reliability differences. Ninety-two occupational therapists and occupational therapy students obtained circumferential measurements of the author's left index finger at the middle of the proximal phalanx utilizing the two methods. The readings obtained for each method were analyzed to determine the coefficient of variation and to compare their variances. The coefficient of variation for the traditional method was 2.92 and for the device utilizing the torque meter was 0.75. The F ratio was 15.63, which is significant at the 0.01 level. The results of this study indicate greater interrater reliability using a device that can accurately measure torque and allow the therapist to control the amount of tension applied when obtaining circumferential measurements using a tape measure.

Reliability of reflectance measures in passive filters

NASA Astrophysics Data System (ADS)

Saldiva de André, Carmen Diva; Afonso de André, Paulo; Rocha, Francisco Marcelo; Saldiva, Paulo Hilário Nascimento; Carvalho de Oliveira, Regiani; Singer, Julio M.

2014-08-01

Measurements of optical reflectance in passive filters impregnated with a reactive chemical solution may be transformed to ozone concentrations via a calibration curve and constitute a low cost alternative for environmental monitoring, mainly to estimate human exposure. Given the possibility of errors caused by exposure bias, it is common to consider sets of m filters exposed during a certain period to estimate the latent reflectance on n different sample occasions at a certain location. Mixed models with sample occasions as random effects are useful to analyze data obtained under such setups. The intra-class correlation coefficient of the mean of the m measurements is an indicator of the reliability of the latent reflectance estimates. Our objective is to determine m in order to obtain a pre-specified reliability of the estimates, taking possible outliers into account. To illustrate the procedure, we consider an experiment conducted at the Laboratory of Experimental Air Pollution, University of São Paulo, Brazil (LPAE/FMUSP), where sets of m = 3 filters were exposed during 7 days on n = 9 different occasions at a certain location. The results show that the reliability of the latent reflectance estimates for each occasion obtained under homoskedasticity is km = 0.74. A residual analysis suggests that the within-occasion variance for two of the occasions should be different from the others. A refined model with two within-occasion variance components was considered, yielding km = 0.56 for these occasions and km = 0.87 for the remaining ones. To guarantee that all estimates have a reliability of at least 80% we require measurements on m = 10 filters on each occasion.

Research on Novel Algorithms for Smart Grid Reliability Assessment and Economic Dispatch

NASA Astrophysics Data System (ADS)

Luo, Wenjin

In this dissertation, several studies of electric power system reliability and economy assessment methods are presented. To be more precise, several algorithms in evaluating power system reliability and economy are studied. Furthermore, two novel algorithms are applied to this field and their simulation results are compared with conventional results. As the electrical power system develops towards extra high voltage, remote distance, large capacity and regional networking, the application of a number of new technique equipments and the electric market system have be gradually established, and the results caused by power cut has become more and more serious. The electrical power system needs the highest possible reliability due to its complication and security. In this dissertation the Boolean logic Driven Markov Process (BDMP) method is studied and applied to evaluate power system reliability. This approach has several benefits. It allows complex dynamic models to be defined, while maintaining its easy readability as conventional methods. This method has been applied to evaluate IEEE reliability test system. The simulation results obtained are close to IEEE experimental data which means that it could be used for future study of the system reliability. Besides reliability, modern power system is expected to be more economic. This dissertation presents a novel evolutionary algorithm named as quantum evolutionary membrane algorithm (QEPS), which combines the concept and theory of quantum-inspired evolutionary algorithm and membrane computation, to solve the economic dispatch problem in renewable power system with on land and offshore wind farms. The case derived from real data is used for simulation tests. Another conventional evolutionary algorithm is also used to solve the same problem for comparison. The experimental results show that the proposed method is quick and accurate to obtain the optimal solution which is the minimum cost for electricity supplied by wind

Reliability in the DSM-III field trials: interview v case summary.

PubMed

Hyler, S E; Williams, J B; Spitzer, R L

1982-11-01

A study compared the reliability of psychiatric diagnoses obtained from the live interviews and from case summaries, on the same patients, by the same clinicians, using the same DSM-III diagnostic criteria. The results showed that the reliability of the major diagnostic classes of DSM-III was higher when diagnoses were made from live interviews than when they were made from case summaries. We conclude that diagnoses based on information contained in traditionally prepared case summaries may lead to an underestimation of the reliability of diagnoses made based on information collected during a "live" interview.

78 FR 73424 - Retirement of Requirements in Reliability Standards

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-06

... predicated on the view that many violations of requirements currently included in Reliability Standards pose... for Bulk-Power System reliability or may be redundant. The Commission is interested in obtaining views... redundant. The Commission is interested in obtaining views on whether such requirements could be removed...

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

NASA Astrophysics Data System (ADS)

Miao, Yongchun; Kang, Rongxue; Chen, Xuefeng

2017-12-01

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

Assessing the Reliability of Material Flow Analysis Results: The Cases of Rhenium, Gallium, and Germanium in the United States Economy.

PubMed

Meylan, Grégoire; Reck, Barbara K; Rechberger, Helmut; Graedel, Thomas E; Schwab, Oliver

2017-10-17

Decision-makers traditionally expect "hard facts" from scientific inquiry, an expectation that the results of material flow analyses (MFAs) can hardly meet. MFA limitations are attributable to incompleteness of flowcharts, limited data quality, and model assumptions. Moreover, MFA results are, for the most part, based less on empirical observation but rather on social knowledge construction processes. Developing, applying, and improving the means of evaluating and communicating the reliability of MFA results is imperative. We apply two recently proposed approaches for making quantitative statements on MFA reliability to national minor metals systems: rhenium, gallium, and germanium in the United States in 2012. We discuss the reliability of results in policy and management contexts. The first approach consists of assessing data quality based on systematic characterization of MFA data and the associated meta-information and quantifying the "information content" of MFAs. The second is a quantification of data inconsistencies indicated by the "degree of data reconciliation" between the data and the model. A high information content and a low degree of reconciliation indicate reliable or certain MFA results. This article contributes to reliability and uncertainty discourses in MFA, exemplifying the usefulness of the approaches in policy and management, and to raw material supply discussions by providing country-level information on three important minor metals often considered critical.

Nanoscale deformation measurements for reliability assessment of material interfaces

NASA Astrophysics Data System (ADS)

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

2006-03-01

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

The reliability of in-training assessment when performance improvement is taken into account.

PubMed

van Lohuizen, Mirjam T; Kuks, Jan B M; van Hell, Elisabeth A; Raat, A N; Stewart, Roy E; Cohen-Schotanus, Janke

2010-12-01

During in-training assessment students are frequently assessed over a longer period of time and therefore it can be expected that their performance will improve. We studied whether there really is a measurable performance improvement when students are assessed over an extended period of time and how this improvement affects the reliability of the overall judgement. In-training assessment results were obtained from 104 students on rotation at our university hospital or at one of the six affiliated hospitals. Generalisability theory was used in combination with multilevel analysis to obtain reliability coefficients and to estimate the number of assessments needed for reliable overall judgement, both including and excluding performance improvement. Students' clinical performance ratings improved significantly from a mean of 7.6 at the start to a mean of 7.8 at the end of their clerkship. When taking performance improvement into account, reliability coefficients were higher. The number of assessments needed to achieve a reliability of 0.80 or higher decreased from 17 to 11. Therefore, when studying reliability of in-training assessment, performance improvement should be considered.

Modified Core Wash Cytology: A reliable same day biopsy result for breast clinics.

PubMed

Bulte, J P; Wauters, C A P; Duijm, L E M; de Wilt, J H W; Strobbe, L J A

2016-12-01

Fine Needle Aspiration Biopsy (FNAB), Core Needle biopsy (CNB) and hybrid techniques including Core Wash Cytology (CWC) are available for same-day diagnosis in breast lesions. In CWC a washing of the biopsy core is processed for a provisional cytological diagnosis, after which the core is processed like a regular CNB. This study focuses on the reliability of CWC in daily practice. All consecutive CWC procedures performed in a referral breast centre between May 2009 and May 2012 were reviewed, correlating CWC results with the CNB result, definitive diagnosis after surgical resection and/or follow-up. Symptomatic as well as screen-detected lesions, undergoing CNB were included. 1253 CWC procedures were performed. Definitive histology showed 849 (68%) malignant and 404 (32%) benign lesions. 80% of CWC procedures yielded a conclusive diagnosis: this percentage was higher amongst malignant lesions and lower for benign lesions: 89% and 62% respectively. Sensitivity and specificity of a conclusive CWC result were respectively 98.3% and 90.4%. The eventual incidence of malignancy in the cytological 'atypical' group (5%) was similar to the cytological 'benign' group (6%). CWC can be used to make a reliable provisional diagnosis of breast lesions within the hour. The high probability of conclusive results in malignant lesions makes CWC well suited for high risk populations. Copyright © 2016 Elsevier Ltd, BASO ~ the Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

Reliability Sampling Plans: A Review and Some New Results

ERIC Educational Resources Information Center

Isaic-Maniu, Alexandru; Voda, Viorel Gh.

2009-01-01

In this work we present a large area of aspects related to the problem of sampling inspection in the case of reliability. First we discuss the actual status of this domain, mentioning the newest approaches (from a technical view point) such as HALT and HASS and the statistical perspective. After a brief description of the general procedure in…

Reliability based design optimization: Formulations and methodologies

NASA Astrophysics Data System (ADS)

Agarwal, Harish

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

fMRI reliability: influences of task and experimental design.

PubMed

Bennett, Craig M; Miller, Michael B

2013-12-01

As scientists, it is imperative that we understand not only the power of our research tools to yield results, but also their ability to obtain similar results over time. This study is an investigation into how common decisions made during the design and analysis of a functional magnetic resonance imaging (fMRI) study can influence the reliability of the statistical results. To that end, we gathered back-to-back test-retest fMRI data during an experiment involving multiple cognitive tasks (episodic recognition and two-back working memory) and multiple fMRI experimental designs (block, event-related genetic sequence, and event-related m-sequence). Using these data, we were able to investigate the relative influences of task, design, statistical contrast (task vs. rest, target vs. nontarget), and statistical thresholding (unthresholded, thresholded) on fMRI reliability, as measured by the intraclass correlation (ICC) coefficient. We also utilized data from a second study to investigate test-retest reliability after an extended, six-month interval. We found that all of the factors above were statistically significant, but that they had varying levels of influence on the observed ICC values. We also found that these factors could interact, increasing or decreasing the relative reliability of certain Task × Design combinations. The results suggest that fMRI reliability is a complex construct whose value may be increased or decreased by specific combinations of factors.

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

PubMed

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.

Reliability analysis of airship remote sensing system

NASA Astrophysics Data System (ADS)

Qin, Jun

1998-08-01

Airship Remote Sensing System (ARSS) for obtain the dynamic or real time images in the remote sensing of the catastrophe and the environment, is a mixed complex system. Its sensor platform is a remote control airship. The achievement of a remote sensing mission depends on a series of factors. For this reason, it is very important for us to analyze reliability of ARSS. In first place, the system model was simplified form multi-stage system to two-state system on the basis of the result of the failure mode and effect analysis and the failure tree failure mode effect and criticality analysis. The failure tree was created after analyzing all factors and their interrelations. This failure tree includes four branches, e.g. engine subsystem, remote control subsystem, airship construction subsystem, flying metrology and climate subsystem. By way of failure tree analysis and basic-events classing, the weak links were discovered. The result of test running shown no difference in comparison with theory analysis. In accordance with the above conclusions, a plan of the reliability growth and reliability maintenance were posed. System's reliability are raised from 89 percent to 92 percent with the reformation of the man-machine interactive interface, the augmentation of the secondary better-groupie and the secondary remote control equipment.

Alberta infant motor scale: reliability and validity when used on preterm infants in Taiwan.

PubMed

Jeng, S F; Yau, K I; Chen, L C; Hsiao, S F

2000-02-01

The goal of this study was to examine the reliability and validity of measurements obtained with the Alberta Infant Motor Scale (AIMS) for evaluation of preterm infants in Taiwan. Two independent groups of preterm infants were used to investigate the reliability (n=45) and validity (n=41) for the AIMS. In the reliability study, the AIMS was administered to the infants by a physical therapist, and infant performance was videotaped. The performance was then rescored by the same therapist and by 2 other therapists to examine the intrarater and interrater reliability. In the validity study, the AIMS and the Bayley Motor Scale were administered to the infants at 6 and 12 months of age to examine criterion-related validity. Intraclass correlation coefficients (ICCs) for intrarater and interrater reliability of measurements obtained with the AIMS were high (ICC=.97-.99). The AIMS scores correlated with the Bayley Motor Scale scores at 6 and 12 months (r=.78 and.90), although the AIMS scores at 6 months were only moderately predictive of the motor function at 12 months (r=.56). The results suggest that measurements obtained with the AIMS have acceptable reliability and concurrent validity but limited predictive value for evaluating preterm Taiwanese infants.

Automated lung volumetry from routine thoracic CT scans: how reliable is the result?

PubMed

Haas, Matthias; Hamm, Bernd; Niehues, Stefan M

2014-05-01

Today, lung volumes can be easily calculated from chest computed tomography (CT) scans. Modern postprocessing workstations allow automated volume measurement of data sets acquired. However, there are challenges in the use of lung volume as an indicator of pulmonary disease when it is obtained from routine CT. Intra-individual variation and methodologic aspects have to be considered. Our goal was to assess the reliability of volumetric measurements in routine CT lung scans. Forty adult cancer patients whose lungs were unaffected by the disease underwent routine chest CT scans in 3-month intervals, resulting in a total number of 302 chest CT scans. Lung volume was calculated by automatic volumetry software. On average of 7.2 CT scans were successfully evaluable per patient (range 2-15). Intra-individual changes were assessed. In the set of patients investigated, lung volume was approximately normally distributed, with a mean of 5283 cm(3) (standard deviation = 947 cm(3), skewness = -0.34, and curtosis = 0.16). Between different scans in one and the same patient the median intra-individual standard deviation in lung volume was 853 cm(3) (16% of the mean lung volume). Automatic lung segmentation of routine chest CT scans allows a technically stable estimation of lung volume. However, substantial intra-individual variations have to be considered. A median intra-individual deviation of 16% in lung volume between different routine scans was found. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

Results of instrument reliability study for high-level nuclear-waste repositories. [Geotechnical parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogue, F.; Binnall, E.P.

1982-10-01

Reliable instrumentation will be needed to monitor the performance of future high-level waste repository sites. A study has been made to assess instrument reliability at Department of Energy (DOE) waste repository related experiments. Though the study covers a wide variety of instrumentation, this paper concentrates on experiences with geotechnical instrumentation in hostile repository-type environments. Manufacturers have made some changes to improve the reliability of instruments for repositories. This paper reviews the failure modes, rates, and mechanisms, along with manufacturer modifications and recommendations for additional improvements to enhance instrument performance. 4 tables.

Emulation applied to reliability analysis of reconfigurable, highly reliable, fault-tolerant computing systems

NASA Technical Reports Server (NTRS)

Migneault, G. E.

1979-01-01

Emulation techniques applied to the analysis of the reliability of highly reliable computer systems for future commercial aircraft are described. The lack of credible precision in reliability estimates obtained by analytical modeling techniques is first established. The difficulty is shown to be an unavoidable consequence of: (1) a high reliability requirement so demanding as to make system evaluation by use testing infeasible; (2) a complex system design technique, fault tolerance; (3) system reliability dominated by errors due to flaws in the system definition; and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. Next, the technique of emulation is described, indicating how its input is a simple description of the logical structure of a system and its output is the consequent behavior. Use of emulation techniques is discussed for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques. Finally an illustrative example is presented to demonstrate from actual use the promise of the proposed application of emulation.

Analysis of the Quality of Information Obtained About Uterine Artery Embolization From the Internet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavare, Aniket N.; Alsafi, Ali, E-mail: ali.alsafi03@imperial.ac.uk; Hamady, Mohamad S.

Purpose: The Internet is widely used by patients to source health care-related information. We sought to analyse the quality of information available on the Internet about uterine artery embolization (UAE). Materials and Methods: We searched three major search engines for the phrase 'uterine artery embolization' and compiled the top 50 results from each engine. After excluding repeated sites, scientific articles, and links to documents, the remaining 50 sites were assessed using the LIDA instrument, which scores sites across the domains of accessibility, usability, and reliability. The Fleisch reading ease score (FRES) was calculated for each of the sites. Finally, wemore » checked the country of origin and the presence of certification by the Health On the Net Foundation (HONcode) as well as their effect on LIDA and FRES scores.ResultsThe following mean scores were obtained: accessibility 48/60 (80%), usability 42/54 (77%), reliability 20/51 (39%), total LIDA 110/165 (67%), and FRES 42/100 (42%). Nine sites had HONcode certification, and this was associated with significantly greater (p < 0.05) reliability and total LIDA and FRES scores. When comparing sites between United Kingdom and United States, there was marked variation in the quality of results obtained when searching for information on UAE (p < 0.05). Conclusion: In general, sites were well designed and easy to use. However, many scored poorly on the reliability of their information either because they were produced in a non-evidence-based way or because they lacking currency. It is important that patients are guided to reputable, location-specific sources of information online, especially because prominent search engine rank does not guarantee reliability of information.« less

Day-to-day reliability of gait characteristics in rats.

PubMed

Raffalt, Peter C; Nielsen, Louise R; Madsen, Stefan; Munk Højberg, Laurits; Pingel, Jessica; Nielsen, Jens Bo; Wienecke, Jacob; Alkjær, Tine

2018-04-27

The purpose of the present study was to determine the day-to-day reliability in stride characteristics in rats during treadmill walking obtained with two-dimensional (2D) motion capture. Kinematics were recorded from 26 adult rats during walking at 8 m/min, 12 m/min and 16 m/min on two separate days. Stride length, stride time, contact time, swing time and hip, knee and ankle joint range of motion were extracted from 15 strides. The relative reliability was assessed using intra-class correlation coefficients (ICC(1,1)) and (ICC(3,1)). The absolute reliability was determined using measurement error (ME). Across walking speeds, the relative reliability ranged from fair to good (ICCs between 0.4 and 0.75). The ME was below 91 mm for strides lengths, below 55 ms for the temporal stride variables and below 6.4° for the joint angle range of motion. In general, the results indicated an acceptable day-to-day reliability of the gait pattern parameters observed in rats during treadmill walking. The results of the present study may serve as a reference material that can help future intervention studies on rat gait characteristics both with respect to the selection of outcome measures and in the interpretation of the results. Copyright © 2018 Elsevier Ltd. All rights reserved.

The reliability of the Australasian Triage Scale: a meta-analysis

PubMed Central

Ebrahimi, Mohsen; Heydari, Abbas; Mazlom, Reza; Mirhaghi, Amir

2015-01-01

BACKGROUND: Although the Australasian Triage Scale (ATS) has been developed two decades ago, its reliability has not been defined; therefore, we present a meta-analyis of the reliability of the ATS in order to reveal to what extent the ATS is reliable. DATA SOURCES: Electronic databases were searched to March 2014. The included studies were those that reported samples size, reliability coefficients, and adequate description of the ATS reliability assessment. The guidelines for reporting reliability and agreement studies (GRRAS) were used. Two reviewers independently examined abstracts and extracted data. The effect size was obtained by the z-transformation of reliability coefficients. Data were pooled with random-effects models, and meta-regression was done based on the method of moment’s estimator. RESULTS: Six studies were included in this study at last. Pooled coefficient for the ATS was substantial 0.428 (95%CI 0.340–0.509). The rate of mis-triage was less than fifty percent. The agreement upon the adult version is higher than the pediatric version. CONCLUSION: The ATS has shown an acceptable level of overall reliability in the emergency department, but it needs more development to reach an almost perfect agreement. PMID:26056538

A Direct Method for Obtaining Approximate Standard Error and Confidence Interval of Maximal Reliability for Composites with Congeneric Measures

ERIC Educational Resources Information Center

Raykov, Tenko; Penev, Spiridon

2006-01-01

Unlike a substantial part of reliability literature in the past, this article is concerned with weighted combinations of a given set of congeneric measures with uncorrelated errors. The relationship between maximal coefficient alpha and maximal reliability for such composites is initially dealt with, and it is shown that the former is a lower…

Reliability and validity of gait analysis by android-based smartphone.

PubMed

Nishiguchi, Shu; Yamada, Minoru; Nagai, Koutatsu; Mori, Shuhei; Kajiwara, Yuu; Sonoda, Takuya; Yoshimura, Kazuya; Yoshitomi, Hiroyuki; Ito, Hiromu; Okamoto, Kazuya; Ito, Tatsuaki; Muto, Shinyo; Ishihara, Tatsuya; Aoyama, Tomoki

2012-05-01

Smartphones are very common devices in daily life that have a built-in tri-axial accelerometer. Similar to previously developed accelerometers, smartphones can be used to assess gait patterns. However, few gait analyses have been performed using smartphones, and their reliability and validity have not been evaluated yet. The purpose of this study was to evaluate the reliability and validity of a smartphone accelerometer. Thirty healthy young adults participated in this study. They walked 20 m at their preferred speeds, and their trunk accelerations were measured using a smartphone and a tri-axial accelerometer that was secured over the L3 spinous process. We developed a gait analysis application and installed it in the smartphone to measure the acceleration. After signal processing, we calculated the gait parameters of each measurement terminal: peak frequency (PF), root mean square (RMS), autocorrelation peak (AC), and coefficient of variance (CV) of the acceleration peak intervals. Remarkable consistency was observed in the test-retest reliability of all the gait parameter results obtained by the smartphone (p<0.001). All the gait parameter results obtained by the smartphone showed statistically significant and considerable correlations with the same parameter results obtained by the tri-axial accelerometer (PF r=0.99, RMS r=0.89, AC r=0.85, CV r=0.82; p<0.01). Our study indicates that the smartphone with gait analysis application used in this study has the capacity to quantify gait parameters with a degree of accuracy that is comparable to that of the tri-axial accelerometer.

Scale for positive aspects of caregiving experience: development, reliability, and factor structure.

PubMed

Kate, N; Grover, S; Kulhara, P; Nehra, R

2012-06-01

OBJECTIVE. To develop an instrument (Scale for Positive Aspects of Caregiving Experience [SPACE]) that evaluates positive caregiving experience and assess its psychometric properties. METHODS. Available scales which assess some aspects of positive caregiving experience were reviewed and a 50-item questionnaire with a 5-point rating was constructed. In all, 203 primary caregivers of patients with severe mental disorders were asked to complete the questionnaire. Internal consistency, test-retest reliability, cross-language reliability, split-half reliability, and face validity were evaluated. Principal component factor analysis was run to assess the factorial validity of the scale. RESULTS. The scale developed as part of the study was found to have good internal consistency, test-retest reliability, cross-language reliability, split-half reliability, and face validity. Principal component factor analysis yielded a 4-factor structure, which also had good test-retest reliability and cross-language reliability. There was a strong correlation between the 4 factors obtained. CONCLUSION. The SPACE developed as part of this study has good psychometric properties.

Reliability of provocative tests of motion sickness susceptibility

NASA Technical Reports Server (NTRS)

Calkins, D. S.; Reschke, M. F.; Kennedy, R. S.; Dunlop, W. P.

1987-01-01

Test-retest reliability values were derived from motion sickness susceptibility scores obtained from two successive exposures to each of three tests: (1) Coriolis sickness sensitivity test; (2) staircase velocity movement test; and (3) parabolic flight static chair test. The reliability of the three tests ranged from 0.70 to 0.88. Normalizing values from predictors with skewed distributions improved the reliability.

Evaluation Applied to Reliability Analysis of Reconfigurable, Highly Reliable, Fault-Tolerant, Computing Systems for Avionics

NASA Technical Reports Server (NTRS)

Migneault, G. E.

1979-01-01

Emulation techniques are proposed as a solution to a difficulty arising in the analysis of the reliability of highly reliable computer systems for future commercial aircraft. The difficulty, viz., the lack of credible precision in reliability estimates obtained by analytical modeling techniques are established. The difficulty is shown to be an unavoidable consequence of: (1) a high reliability requirement so demanding as to make system evaluation by use testing infeasible, (2) a complex system design technique, fault tolerance, (3) system reliability dominated by errors due to flaws in the system definition, and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. The technique of emulation is described, indicating how its input is a simple description of the logical structure of a system and its output is the consequent behavior. The use of emulation techniques is discussed for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques.

The Reliability of Difference Scores in Populations and Samples

ERIC Educational Resources Information Center

Zimmerman, Donald W.

2009-01-01

This study was an investigation of the relation between the reliability of difference scores, considered as a parameter characterizing a population of examinees, and the reliability estimates obtained from random samples from the population. The parameters in familiar equations for the reliability of difference scores were redefined in such a way…

Reliability of the Load-Velocity Relationship Obtained Through Linear and Polynomial Regression Models to Predict the One-Repetition Maximum Load.

PubMed

Pestaña-Melero, Francisco Luis; Haff, G Gregory; Rojas, Francisco Javier; Pérez-Castilla, Alejandro; García-Ramos, Amador

2017-12-18

This study aimed to compare the between-session reliability of the load-velocity relationship between (1) linear vs. polynomial regression models, (2) concentric-only vs. eccentric-concentric bench press variants, as well as (3) the within-participants vs. the between-participants variability of the velocity attained at each percentage of the one-repetition maximum (%1RM). The load-velocity relationship of 30 men (age: 21.2±3.8 y; height: 1.78±0.07 m, body mass: 72.3±7.3 kg; bench press 1RM: 78.8±13.2 kg) were evaluated by means of linear and polynomial regression models in the concentric-only and eccentric-concentric bench press variants in a Smith Machine. Two sessions were performed with each bench press variant. The main findings were: (1) first-order-polynomials (CV: 4.39%-4.70%) provided the load-velocity relationship with higher reliability than second-order-polynomials (CV: 4.68%-5.04%); (2) the reliability of the load-velocity relationship did not differ between the concentric-only and eccentric-concentric bench press variants; (3) the within-participants variability of the velocity attained at each %1RM was markedly lower than the between-participants variability. Taken together, these results highlight that, regardless of the bench press variant considered, the individual determination of the load-velocity relationship by a linear regression model could be recommended to monitor and prescribe the relative load in the Smith machine bench press exercise.

The Reliability and Validity of the Computerized Double Inclinometer in Measuring Lumbar Mobility

PubMed Central

MacDermid, Joy Christine; Arumugam, Vanitha; Vincent, Joshua Israel; Carroll, Krista L

2014-01-01

Study Design : Repeated measures reliability/validity study. Objectives : To determine the concurrent validity, test-retest, inter-rater and intra-rater reliability of lumbar flexion and extension measurements using the Tracker M.E. computerized dual inclinometer (CDI) in comparison to the modified-modified Schober (MMS) Summary of Background : Numerous studies have evaluated the reliability and validity of the various methods of measuring spinal motion, but the results are inconsistent. Differences in equipment and techniques make it difficult to correlate results. Methods : Twenty subjects with back pain and twenty without back pain were selected through convenience sampling. Two examiners measured sagittal plane lumbar range of motion for each subject. Two separate tests with the CDI and one test with the MMS were conducted. Each test consisted of three trials. Instrument and examiner order was randomly assigned. Intra-class correlations (ICCs 2, 2 and 2, 2) and Pearson correlation coefficients (r) were used to calculate reliability and concurrent validity respectively. Results : Intra-trial reliability was high to very high for both the CDI (ICCs 0.85 - 0.96) and MMS (ICCs 0.84 - 0.98). However, the reliability was poor to moderate, when the CDI unit had to be repositioned either by the same rate (ICCs 0.16 - 0.59) or a different rater (ICCs 0.45 - 0.52). Inter-rater reliability for the MMS was moderate to high (ICCs 0.75 - 0.82) which bettered the moderate correlation obtained for the CDI (ICCs 0.45 - 0.52). Correlations between the CDI and MMS were poor for flexion (0.32; p<0.05) and poor to moderate (-0.42 - -0.51; p<0.05) for extension measurements. Conclusion : When using the CDI, an average of subsequent tests is required to obtain moderate reliability. The MMS was highly reliable than the CDI. The MMS and the CDI measure lumbar movement on a different metric that are not highly related to each other. PMID:25352928

Real-time reliability measure-driven multi-hypothesis tracking using 2D and 3D features

NASA Astrophysics Data System (ADS)

Zúñiga, Marcos D.; Brémond, François; Thonnat, Monique

2011-12-01

We propose a new multi-target tracking approach, which is able to reliably track multiple objects even with poor segmentation results due to noisy environments. The approach takes advantage of a new dual object model combining 2D and 3D features through reliability measures. In order to obtain these 3D features, a new classifier associates an object class label to each moving region (e.g. person, vehicle), a parallelepiped model and visual reliability measures of its attributes. These reliability measures allow to properly weight the contribution of noisy, erroneous or false data in order to better maintain the integrity of the object dynamics model. Then, a new multi-target tracking algorithm uses these object descriptions to generate tracking hypotheses about the objects moving in the scene. This tracking approach is able to manage many-to-many visual target correspondences. For achieving this characteristic, the algorithm takes advantage of 3D models for merging dissociated visual evidence (moving regions) potentially corresponding to the same real object, according to previously obtained information. The tracking approach has been validated using video surveillance benchmarks publicly accessible. The obtained performance is real time and the results are competitive compared with other tracking algorithms, with minimal (or null) reconfiguration effort between different videos.

Electronic device for endosurgical skills training (EDEST): study of reliability.

PubMed

Pagador, J B; Uson, J; Sánchez, M A; Moyano, J L; Moreno, J; Bustos, P; Mateos, J; Sánchez-Margallo, F M

2011-05-01

Minimally Invasive Surgery procedures are commonly used in many surgical practices, but surgeons need specific training models and devices due to its difficulty and complexity. In this paper, an innovative electronic device for endosurgical skills training (EDEST) is presented. A study on reliability for this device was performed. Different electronic components were used to compose this new training device. The EDEST was focused on two basic laparoscopic tasks: triangulation and coordination manoeuvres. A configuration and statistical software was developed to complement the functionality of the device. A calibration method was used to assure the proper work of the device. A total of 35 subjects (8 experts and 27 novices) were used to check the reliability of the system using the MTBF analysis. Configuration values for triangulation and coordination exercises were calculated as 0.5 s limit threshold and 800-11,000 lux range of light intensity, respectively. Zero errors in 1,050 executions (0%) for triangulation and 21 errors in 5,670 executions (0.37%) for coordination were obtained. A MTBF of 2.97 h was obtained. The results show that the reliability of the EDEST device is acceptable when used under previously defined light conditions. These results along with previous work could demonstrate that the EDEST device can help surgeons during first training stages.

Reliability of bounce drop jump parameters within elite male rugby players.

PubMed

Costley, Lisa; Wallace, Eric; Johnston, Michael; Kennedy, Rodney

2017-07-25

The aims of the study were to investigate the number of familiarisation sessions required to establish reliability of the bounce drop jump (BDJ) and subsequent reliability once familiarisation is achieved. Seventeen trained male athletes completed 4 BDJs in 4 separate testing sessions. Force-time data from a 20 cm BDJ was obtained using two force plates (ensuring ground contact < 250 ms). Subjects were instructed to 'jump for maximal height and minimal contact time' while the best and average of four jumps were compared. A series of performance variables were assessed in both eccentric and concentric phases including jump height, contact time, flight time, reactive strength index (RSI), peak power, rate of force development (RFD) and actual dropping height (ADH). Reliability was assessed using the intraclass correlation coefficient (ICC) and coefficient of variation (CV) while familiarisation was assessed using a repeated measures analysis of variance (ANOVA). The majority of DJ parameters exhibited excellent reliability with no systematic bias evident, while the average of 4 trials provided greater reliability. With the exception of vertical stiffness (CV: 12.0 %) and RFD (CV: 16.2 %) all variables demonstrated low within subject variation (CV range: 3.1 - 8.9 %). Relative reliability was very poor for ADH, with heights ranging from 14.87 - 29.85 cm. High levels of reliability can be obtained from the BDJ with the exception of vertical stiffness and RFD, however, extreme caution must be taken when comparing DJ results between individuals and squads due to large discrepancies between actual drop height and platform height.

Alternate Forms Reliability of the Behavioral Relaxation Scale: Preliminary Results

ERIC Educational Resources Information Center

Lundervold, Duane A.; Dunlap, Angel L.

2006-01-01

Alternate forms reliability of the Behavioral Relaxation Scale (BRS; Poppen,1998), a direct observation measure of relaxed behavior, was examined. A single BRS score, based on long duration observation (5-minute), has been found to be a valid measure of relaxation and is correlated with self-report and some physiological measures. Recently,…

The reliability of a quality appraisal tool for studies of diagnostic reliability (QAREL).

PubMed

Lucas, Nicholas; Macaskill, Petra; Irwig, Les; Moran, Robert; Rickards, Luke; Turner, Robin; Bogduk, Nikolai

2013-09-09

The aim of this project was to investigate the reliability of a new 11-item quality appraisal tool for studies of diagnostic reliability (QAREL). The tool was tested on studies reporting the reliability of any physical examination procedure. The reliability of physical examination is a challenging area to study given the complex testing procedures, the range of tests, and lack of procedural standardisation. Three reviewers used QAREL to independently rate 29 articles, comprising 30 studies, published during 2007. The articles were identified from a search of relevant databases using the following string: "Reproducibility of results (MeSH) OR reliability (t.w.) AND Physical examination (MeSH) OR physical examination (t.w.)." A total of 415 articles were retrieved and screened for inclusion. The reviewers undertook an independent trial assessment prior to data collection, followed by a general discussion about how to score each item. At no time did the reviewers discuss individual papers. Reliability was assessed for each item using multi-rater kappa (κ). Multi-rater reliability estimates ranged from κ = 0.27 to 0.92 across all items. Six items were recorded with good reliability (κ > 0.60), three with moderate reliability (κ = 0.41 - 0.60), and two with fair reliability (κ = 0.21 - 0.40). Raters found it difficult to agree about the spectrum of patients included in a study (Item 1) and the correct application and interpretation of the test (Item 10). In this study, we found that QAREL was a reliable assessment tool for studies of diagnostic reliability when raters agreed upon criteria for the interpretation of each item. Nine out of 11 items had good or moderate reliability, and two items achieved fair reliability. The heterogeneity in the tests included in this study may have resulted in an underestimation of the reliability of these two items. We discuss these and other factors that could affect our results and make recommendations for the use of QAREL.

Comparison of the identification results of Candida species obtained by BD Phoenix™ and Maldi-TOF (Bruker Microflex LT Biotyper 3.1).

PubMed

Marucco, Andrea P; Minervini, Patricia; Snitman, Gabriela V; Sorge, Adriana; Guelfand, Liliana I; Moral, Laura López

2018-02-05

In patients with invasive fungal infections, the accurate and rapid identification of the genus Candida is of utmost importance since antimycotic sensitivity is closely related to the species. The aim of the present study was to compare the identification results of species of the genus Candida obtained by BD Phoenix™ (Becton Dickinson [BD]) and Maldi-TOF MS (Bruker Microflex LT Biotyper 3.1). A total of 192 isolates from the strain collection belonging to the Mycology Network of the Autonomous City of Buenos Aires, Argentina, were analyzed. The observed concordance was 95%. Only 10 strains (5%) were not correctly identified by the BD Phoenix™ system. The average identification time with the Yeast ID panels was 8h 22min. The BD Phoenix™ system proved to be a simple, reliable and effective method for identifying the main species of the genus Candida. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Reliability based fatigue design and maintenance procedures

NASA Technical Reports Server (NTRS)

Hanagud, S.

1977-01-01

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

Reliability of the nursing care hour measure: a descriptive study.

PubMed

Klaus, Susan F; Dunton, Nancy; Gajewski, Byron; Potter, Catima

2013-07-01

The nursing care hour has become an international standard unit of measure in research where nurse staffing is a key variable. Until now, there have been no studies verifying whether nursing care hours obtained from hospital data sources can be collected reliably. To examine the processes used by hospitals to generate nursing care hour data and to evaluate inter-rater reliability and guideline compliance with standards of the National Database of Nursing Quality Indicators(®) (NDNQI(®)) and the National Quality Forum. Two-phase descriptive study of all NDNQI hospitals that submitted data in third quarter of 2007. Data for phase I came from an online survey created by the authors to ascertain the processes used by hospitals to collect nursing care hours and their compliance with standardized data collection guidelines. In phase II, inter-rater reliability was measured using intra-class correlations between nursing care hours generated from clock hour files submitted to the study team by participants' payroll/accounting departments and aggregated data submitted previously. Phase I data were obtained from a total of 714 respondents. Nearly half (48%) of all sites use payroll records to obtain nursing care hour data and 70% use one of the standardized methods for converting the bi-weekly hours into months. Unit secretaries were reportedly included in NCH by 17.4% of respondents and only 26.2% of sites could accurately identify the point at which newly hired nurses should be included. The phase II findings (n=11) support the ability of two independent raters to obtain similar results when calculating total nursing care hours according to standard guidelines (ICC=0.76-0.99). Although barriers exist, this study found support for hospitals' abilities to collect reliable nursing care hour data. Copyright © 2012 Elsevier Ltd. All rights reserved.

Software reliability studies

NASA Technical Reports Server (NTRS)

Wilson, Larry W.

1989-01-01

The longterm goal of this research is to identify or create a model for use in analyzing the reliability of flight control software. The immediate tasks addressed are the creation of data useful to the study of software reliability and production of results pertinent to software reliability through the analysis of existing reliability models and data. The completed data creation portion of this research consists of a Generic Checkout System (GCS) design document created in cooperation with NASA and Research Triangle Institute (RTI) experimenters. This will lead to design and code reviews with the resulting product being one of the versions used in the Terminal Descent Experiment being conducted by the Systems Validations Methods Branch (SVMB) of NASA/Langley. An appended paper details an investigation of the Jelinski-Moranda and Geometric models for software reliability. The models were given data from a process that they have correctly simulated and asked to make predictions about the reliability of that process. It was found that either model will usually fail to make good predictions. These problems were attributed to randomness in the data and replication of data was recommended.

Estimation and enhancement of real-time software reliability through mutation analysis

NASA Technical Reports Server (NTRS)

Geist, Robert; Offutt, A. J.; Harris, Frederick C., Jr.

1992-01-01

A simulation-based technique for obtaining numerical estimates of the reliability of N-version, real-time software is presented. An extended stochastic Petri net is employed to represent the synchronization structure of N versions of the software, where dependencies among versions are modeled through correlated sampling of module execution times. Test results utilizing specifications for NASA's planetary lander control software indicate that mutation-based testing could hold greater potential for enhancing reliability than the desirable but perhaps unachievable goal of independence among N versions.

Safety Climate Survey: reliability of results from a multicenter ICU survey.

PubMed

Kho, M E; Carbone, J M; Lucas, J; Cook, D J

2005-08-01

It is important to understand the clinical properties of instruments used to measure patient safety before they are used in the setting of an intensive care unit (ICU). The Safety Climate Survey (SCSu), an instrument endorsed by the Institute for Healthcare Improvement, the Safety Culture Scale (SCSc), and the Safety Climate Mean (SCM), a subset of seven items from the SCSu, were administered in four Canadian university affiliated ICUs. All staff including nurses, allied healthcare professionals, non-clinical staff, intensivists, and managers were invited to participate in the cross sectional survey. The response rate was 74% (313/426). The internal consistency of the SCSu and SCSc was 0.86 and 0.80, respectively, while the SCM performed poorly at 0.51. Because of poor internal consistency, no further analysis of the SCM was therefore performed. Test-retest reliability of the SCSu and SCSc was 0.92. Out of a maximum score of 5, the mean (SD) scores of the SCSu and SCSc were 3.4 (0.6) and 3.4 (0.7), respectively. No differences were noted between the three medical-surgical and one cardiovascular ICU. Managers perceived a significantly more positive safety climate than other staff, as measured by the SCSu and SCSc. These results need to be interpreted cautiously because of the small number of management participants. Of the three instruments, the SCSu and SCSc appear to be measuring one construct and are sufficiently reliable. Future research should examine the properties of patient safety instruments in other ICUs, including responsiveness to change, to ensure that they are valid outcome measures for patient safety initiatives.

Reliability Analysis and Reliability-Based Design Optimization of Circular Composite Cylinders Under Axial Compression

NASA Technical Reports Server (NTRS)

Rais-Rohani, Masoud

2001-01-01

This report describes the preliminary results of an investigation on component reliability analysis and reliability-based design optimization of thin-walled circular composite cylinders with average diameter and average length of 15 inches. Structural reliability is based on axial buckling strength of the cylinder. Both Monte Carlo simulation and First Order Reliability Method are considered for reliability analysis with the latter incorporated into the reliability-based structural optimization problem. To improve the efficiency of reliability sensitivity analysis and design optimization solution, the buckling strength of the cylinder is estimated using a second-order response surface model. The sensitivity of the reliability index with respect to the mean and standard deviation of each random variable is calculated and compared. The reliability index is found to be extremely sensitive to the applied load and elastic modulus of the material in the fiber direction. The cylinder diameter was found to have the third highest impact on the reliability index. Also the uncertainty in the applied load, captured by examining different values for its coefficient of variation, is found to have a large influence on cylinder reliability. The optimization problem for minimum weight is solved subject to a design constraint on element reliability index. The methodology, solution procedure and optimization results are included in this report.

Performance of intraclass correlation coefficient (ICC) as a reliability index under various distributions in scale reliability studies.

PubMed

Mehta, Shraddha; Bastero-Caballero, Rowena F; Sun, Yijun; Zhu, Ray; Murphy, Diane K; Hardas, Bhushan; Koch, Gary

2018-04-29

Many published scale validation studies determine inter-rater reliability using the intra-class correlation coefficient (ICC). However, the use of this statistic must consider its advantages, limitations, and applicability. This paper evaluates how interaction of subject distribution, sample size, and levels of rater disagreement affects ICC and provides an approach for obtaining relevant ICC estimates under suboptimal conditions. Simulation results suggest that for a fixed number of subjects, ICC from the convex distribution is smaller than ICC for the uniform distribution, which in turn is smaller than ICC for the concave distribution. The variance component estimates also show that the dissimilarity of ICC among distributions is attributed to the study design (ie, distribution of subjects) component of subject variability and not the scale quality component of rater error variability. The dependency of ICC on the distribution of subjects makes it difficult to compare results across reliability studies. Hence, it is proposed that reliability studies should be designed using a uniform distribution of subjects because of the standardization it provides for representing objective disagreement. In the absence of uniform distribution, a sampling method is proposed to reduce the non-uniformity. In addition, as expected, high levels of disagreement result in low ICC, and when the type of distribution is fixed, any increase in the number of subjects beyond a moderately large specification such as n = 80 does not have a major impact on ICC. Copyright © 2018 John Wiley & Sons, Ltd.

Neurology objective structured clinical examination reliability using generalizability theory

PubMed Central

Park, Yoon Soo; Lukas, Rimas V.; Brorson, James R.

2015-01-01

Objectives: This study examines factors affecting reliability, or consistency of assessment scores, from an objective structured clinical examination (OSCE) in neurology through generalizability theory (G theory). Methods: Data include assessments from a multistation OSCE taken by 194 medical students at the completion of a neurology clerkship. Facets evaluated in this study include cases, domains, and items. Domains refer to areas of skill (or constructs) that the OSCE measures. G theory is used to estimate variance components associated with each facet, derive reliability, and project the number of cases required to obtain a reliable (consistent, precise) score. Results: Reliability using G theory is moderate (Φ coefficient = 0.61, G coefficient = 0.64). Performance is similar across cases but differs by the particular domain, such that the majority of variance is attributed to the domain. Projections in reliability estimates reveal that students need to participate in 3 OSCE cases in order to increase reliability beyond the 0.70 threshold. Conclusions: This novel use of G theory in evaluating an OSCE in neurology provides meaningful measurement characteristics of the assessment. Differing from prior work in other medical specialties, the cases students were randomly assigned did not influence their OSCE score; rather, scores varied in expected fashion by domain assessed. PMID:26432851

Report on Wind Turbine Subsystem Reliability - A Survey of Various Databases (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, S.

2013-07-01

Wind industry has been challenged by premature subsystem/component failures. Various reliability data collection efforts have demonstrated their values in supporting wind turbine reliability and availability research & development and industrial activities. However, most information on these data collection efforts are scattered and not in a centralized place. With the objective of getting updated reliability statistics of wind turbines and/or subsystems so as to benefit future wind reliability and availability activities, this report is put together based on a survey of various reliability databases that are accessible directly or indirectly by NREL. For each database, whenever feasible, a brief description summarizingmore » database population, life span, and data collected is given along with its features & status. Then selective results deemed beneficial to the industry and generated based on the database are highlighted. This report concludes with several observations obtained throughout the survey and several reliability data collection opportunities in the future.« less

Theory of reliable systems. [systems analysis and design

NASA Technical Reports Server (NTRS)

Meyer, J. F.

1973-01-01

The analysis and design of reliable systems are discussed. The attributes of system reliability studied are fault tolerance, diagnosability, and reconfigurability. Objectives of the study include: to determine properties of system structure that are conducive to a particular attribute; to determine methods for obtaining reliable realizations of a given system; and to determine how properties of system behavior relate to the complexity of fault tolerant realizations. A list of 34 references is included.

Validity and reliability of a new ankle dorsiflexion measurement device.

PubMed

Gatt, Alfred; Chockalingam, Nachiappan

2013-08-01

The assessment of the maximum ankle dorsiflexion angle is an important clinical examination procedure. Evidence shows that the traditional goniometer is highly unreliable, and various designs of goniometers to measure the maximum ankle dorsiflexion angle rely on the application of a known force to obtain reliable results. Hence, an innovative ankle dorsiflexion measurement device was designed to make this measurement more reliable by holding the foot in a selected posture without the application of a known moment. To report on the comprehensive validity and reliability testing carried out on the new device. Following validity testing, four different trials to test reliability of the ankle dorsiflexion measurement device were performed. These trials included inter-rater and intra-rater testings with a controlled moment, intra-rater reliability testing with knees flexed and extended without a controlled moment, intra-rater testing with a patient population, and inter-rater reliability testing between four raters of varying experience without controlling moment. All raters were blinded. A series of trials to test intra-rater and inter-rater reliabilities. Intra-rater reliability intraclass correlation coefficient was 0.98 and inter-rater reliability intraclass correlation coefficient (2,1) was 0.953 with a controlled moment. With uncontrolled moment, very high reliability for intra-tester was also achieved (intraclass correlation coefficient = 0.94 with knees extended and intraclass correlation coefficient = 0.95 with knees flexed). For the trial investigating test-retest reliability with actual patients, intraclass correlation coefficient of 0.99 was obtained. In the trial investigating four different raters with uncontrolled moment, intraclass correlation coefficient of 0.91 was achieved. The new ankle dorsiflexion measurement device is a valid and reliable device for measuring ankle dorsiflexion in both healthy subjects and patients, with both controlled and

Vp and Vs seismic velocity models of the Sicilian-Tyrrhenian region using local earthquake data. Assessment tests to obtain reliable velocity models

NASA Astrophysics Data System (ADS)

Parisi, L.; Calo, M.; Luzio, D.; Sulli, A.

2011-12-01

In this work we present Vp and Vs velocity models of the crust and uppermost mantle beneath the Sicilian-Tyrrhenian region (Southern Italy). We applied the double-difference tomography of Zhang and Thurber (2003) further optimized by the post-processing Weighted Average Model method (Calò et al., 2009; Calò, 2009). The tomographic method was applied to three datasets. The first dataset contains 31270 P- and 13588 S- absolute data and 73022 P- and 27893 S- differential times regarding earthquakes occurred from 1981 to 2005 and recorded by 192 stations. The second dataset is composed by 27668 P- and 11183 S- absolute data and 63296 P- and 29683 S- differential times of earthquakes occurred between January 2006 and December 2009 and recorded by 140 stations. The third dataset results as a merging of the two datasets above described. After an assessment of the results obtained after the inversion of the three datasets, we constructed the final Vp and Vs models as syntheses of all results using the WAM method. Checkerboard tests indicate that horizontal resolution allow to recovery velocity structures 20 km wide in the southern Tyrrhenian Sea and north-eastern Sicily area whereas anomalies of from 40 to 70 km are restored in the southern part of Sicily, Ionian Sea and Sicily Channel. Vertical resolution is 3 km in the shallower parts of the models (down to about 20 km) and 8 -10 km in the deeper ones (down to 50 km). Furthermore, a Vp- Vs correlation analysis was performed in order to assess the minimum threshold of DWS (Toomey and Foulger, 1986) that ensures a sufficient reliability of the seismic velocity distributions. These preliminary results show highly resolved Vp and Vs models and provide new constrains on the lithospheric structures of the study area.

KRAS mutation testing in colorectal cancer: comparison of the results obtained using 3 different methods for the analysis of codons G12 and G13.

PubMed

Bihl, Michel P; Hoeller, Sylvia; Andreozzi, Maria Carla; Foerster, Anja; Rufle, Alexander; Tornillo, Luigi; Terracciano, Luigi

2012-03-01

Targeting the epidermal growth factor receptor (EGFR) is a new therapeutic option for patients with metastatic colorectal or lung carcinoma. However, the therapy efficiency highly depends on the KRAS mutation status in the given tumour. Therefore a reliable and secure KRAS mutation testing is crucial. Here we investigated 100 colorectal carcinoma samples with known KRAS mutation status (62 mutated cases and 38 wild type cases) in a comparative manner with three different KRAS mutation testing techniques (Pyrosequencing, Dideoxysequencing and INFINITI) in order to test their reliability and sensitivity. For the large majority of samples (96/100, 96%), the KRAS mutation status obtained by all three methods was the same. Only two cases with clear discrepancies were observed. One case was reported as wild type by the INFINITI method while the two other methods detected a G13C mutation. In the second case the mutation could be detected by the Pyrosequencing and INFINITI method (15% and 15%), while no signal for mutation could be observed with the Dideoxysequencing method. Additional two unclear results were due to a detection of a G12V with the INFINITI method, which was below cut-off when repeated and which was not detectable by the other two methods and very weak signals in a G12V mutated case with the Dideoxy- and Pyroseqencing method compared to the INFINITI method, respectively. In summary all three methods are reliable and robust methods in detecting KRAS mutations. INFINITI, however seems to be slightly more sensitive compared to Dideoxy- and Pyrosequencing.

Obtaining patient test results from clinical laboratories: a survey of state law for pharmacists.

PubMed

Witry, Matthew J; Doucette, William R

2009-01-01

To identify states with laws that restrict to whom clinical laboratories may release copies of laboratory test results and to describe how these laws may affect pharmacists' ability to obtain patient laboratory test results. Researchers examined state statutes and administrative codes for all 50 states and the District of Columbia at the University of Iowa Law Library between June and July 2007. Researchers also consulted with lawyers, state Clinical Laboratory Improvement Amendments officers, and law librarians. Laws relating to the study objective were analyzed. 34 jurisdictions do not restrict the release of laboratory test results, while 17 states have laws that restrict to whom clinical laboratories can send copies of test results. In these states, pharmacists will have to use alternative sources, such as physician offices, to obtain test results. Pharmacists must consider state law before requesting copies of laboratory test results from clinical laboratories. This may be an issue that state pharmacy associations can address to increase pharmacist access to important patient information.

An experimental evaluation of software redundancy as a strategy for improving reliability

NASA Technical Reports Server (NTRS)

Eckhardt, Dave E., Jr.; Caglayan, Alper K.; Knight, John C.; Lee, Larry D.; Mcallister, David F.; Vouk, Mladen A.; Kelly, John P. J.

1990-01-01

The strategy of using multiple versions of independently developed software as a means to tolerate residual software design faults is suggested by the success of hardware redundancy for tolerating hardware failures. Although, as generally accepted, the independence of hardware failures resulting from physical wearout can lead to substantial increases in reliability for redundant hardware structures, a similar conclusion is not immediate for software. The degree to which design faults are manifested as independent failures determines the effectiveness of redundancy as a method for improving software reliability. Interest in multi-version software centers on whether it provides an adequate measure of increased reliability to warrant its use in critical applications. The effectiveness of multi-version software is studied by comparing estimates of the failure probabilities of these systems with the failure probabilities of single versions. The estimates are obtained under a model of dependent failures and compared with estimates obtained when failures are assumed to be independent. The experimental results are based on twenty versions of an aerospace application developed and certified by sixty programmers from four universities. Descriptions of the application, development and certification processes, and operational evaluation are given together with an analysis of the twenty versions.

Simulation of Swap-Out Reliability For The Advance Photon Source Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borland, M.

2017-06-01

The proposed upgrade of the Advanced Photon Source (APS) to a multibend-achromat lattice relies on the use of swap-out injection to accommodate the small dynamic acceptance, allow use of unusual insertion devices, and minimize collective effects at high single-bunch charge. This, combined with the short beam lifetime, will make injector reliability even more important than it is for top-up operation. We used historical data for the APS injector complex to obtain probability distributions for injector up-time and down-time durations. Using these distributions, we simulated several years of swap-out operation for the upgraded lattice for several operatingmodes. The results indicate thatmore » obtaining very high availability of beam in the storage ring will require improvements to injector reliability.« less

Reliability of Pain Measurements Using Computerized Cuff Algometry: A DoloCuff Reliability and Agreement Study.

PubMed

Kvistgaard Olsen, Jack; Fener, Dilay Kesgin; Waehrens, Eva Elisabet; Wulf Christensen, Anton; Jespersen, Anders; Danneskiold-Samsøe, Bente; Bartels, Else Marie

2017-07-01

Computerized pneumatic cuff pressure algometry (CPA) using the DoloCuff is a new method for pain assessment. Intra- and inter-rater reliabilities have not yet been established. Our aim was to examine the inter- and intrarater reliabilities of DoloCuff measures in healthy subjects. Twenty healthy subjects (ages 20 to 29 years) were assessed three times at 24-hour intervals by two trained raters. Inter-rater reliability was established based on the first and second assessments, whereas intrarater reliability was based on the second and third assessments. Subjects were randomized 1:1 to first assessment at either rater 1 or rater 2. The variables of interest were pressure pain threshold (PT), pressure pain tolerance (PTol), and temporal summation index (TSI). Reliability was estimated by a two-way mixed intraclass correlation coefficient (ICC) absolute agreement analysis. Reliability was considered excellent if ICC > 0.75, fair to good if 0.4 < ICC < 0.75, and poor if ICC < 0.4. Bias and random errors between raters and assessments were evaluated using 95% confidence interval (CI) and Bland-Altman plots. Inter-rater reliability for PT, PTol, and TSI was 0.88 (95% CI: 0.69 to 0.95), 0.86 (95% CI: 0.65 to 0.95), and 0.81 (95% CI: 0.42 to 0.94), respectively. The intrarater reliability for PT, PTol, and TSI was 0.81 (95% CI: 0.53 to 0.92), 0.89 (95% CI: 0.74 to 0.96), and 0.75 (95% CI: 0.28 to 0.91), respectively. Inter-rater reliability was excellent for PT, PTol, and TSI. Similarly, the intrarater reliability for PT and PTol was excellent, while borderline excellent/good for TSI. Therefore, the DoloCuff can be used to obtain reliable measures of pressure pain parameters in healthy subjects. © 2016 World Institute of Pain.

Reliability and maintainability assessment factors for reliable fault-tolerant systems

NASA Technical Reports Server (NTRS)

Bavuso, S. J.

1984-01-01

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

Statistics-related and reliability-physics-related failure processes in electronics devices and products

NASA Astrophysics Data System (ADS)

Suhir, E.

2014-05-01

The well known and widely used experimental reliability "passport" of a mass manufactured electronic or a photonic product — the bathtub curve — reflects the combined contribution of the statistics-related and reliability-physics (physics-of-failure)-related processes. When time progresses, the first process results in a decreasing failure rate, while the second process associated with the material aging and degradation leads to an increased failure rate. An attempt has been made in this analysis to assess the level of the reliability physics-related aging process from the available bathtub curve (diagram). It is assumed that the products of interest underwent the burn-in testing and therefore the obtained bathtub curve does not contain the infant mortality portion. It has been also assumed that the two random processes in question are statistically independent, and that the failure rate of the physical process can be obtained by deducting the theoretically assessed statistical failure rate from the bathtub curve ordinates. In the carried out numerical example, the Raleigh distribution for the statistical failure rate was used, for the sake of a relatively simple illustration. The developed methodology can be used in reliability physics evaluations, when there is a need to better understand the roles of the statistics-related and reliability-physics-related irreversible random processes in reliability evaluations. The future work should include investigations on how powerful and flexible methods and approaches of the statistical mechanics can be effectively employed, in addition to reliability physics techniques, to model the operational reliability of electronic and photonic products.

Comparison of BOD results obtained by dilution and manometric methods in sanitary landfill leachates.

PubMed

Ceçen, F; Yangin, C

2000-12-01

This study examined the determination of BOD in landfill leachates by dilution (D-method) and manometric methods (M-method). The differences in results were discussed based on statistical tests. The effects of sample dilution, seeding, chloride and total Kjeldahl nitrogen (TKN) level were examined. The M-method was found to be more sensitive to increases in chloride and TKN concentrations. However, in the M-method the positive interference of nitrogenous BOD (NBOD) to carbonaceous BOD (CBOD) was more successfully prevented. The BOD rate constant k and the ultimate BOD (BODu) were estimated by non-linear regression. With the M-method these parameters could be more reliably estimated than the D-method. Suggestions were made for BOD analyses in landfill leachates in future studies.

Toward Obtaining Reliable Particulate Air Quality Information from Satellites

NASA Astrophysics Data System (ADS)

Strawa, A. W.; Chatfield, R. B.; Legg, M.; Esswein, R.; Justice, E.

2009-12-01

Air quality agencies use ground sites to monitor air quality, providing accurate information at particular points. Using measurements from satellite imagery has the potential to provide air quality information in a timely manner with better spatial resolution and at a lower cost that can also useful for model validation. While previous studies show acceptable correlations between Aerosol Optical Depth (AOD) derived from MODIS and surface Particulate Matter (PM) measurements on the eastern US, the data do not correlate well in the western US (Al-Saadi et al., 2005; Engle-Cox et al., 2004) . This paper seeks to improve the AOD-PM correlations by using advanced statistical analysis techniques. Our study area is the San Joaquin Valley in California because air quality in this region has failed to meet state and federal attainment standards for PM for the past several years. A previous investigation found good correlation of the AOD values between MODIS, MISR and AERONET, but poor correlations (R2 ~ 0.02) between satellite-based AOD and surface PM2.5 measurements. PM2.5 measurements correlated somewhat better (R2 ~ 0.18) with MODIS-derived AOD using the Deep Blue surface reflectance algorithm (Hsu et al., 2006) rather than the standard MODIS algorithm. This level of correlation is not adequate for reliable air quality measurements. Pelletier et al. (2007) used generalized additive models (GAMs) and meteorological data to improve the correlation between PM and AERONET AOD in western Europe. Additive models are more flexible than linear models and the functional relationships can be plotted to give a sense of the relationship between the predictor and the response. In this paper we use GAMs to improve surface PM2.5 to MODIS-AOD correlations. For example, we achieve an R2 ~ 0.44 using a GAM that includes the Deep Blue AOD, and day of year as parameters. Including NOx observations, improves the R2 ~ 0.64. Surprisingly Ångström exponent did not prove to be a significant

The Reliability and Stability of an Inferred Phylogenetic Tree from Empirical Data.

PubMed

Katsura, Yukako; Stanley, Craig E; Kumar, Sudhir; Nei, Masatoshi

2017-03-01

The reliability of a phylogenetic tree obtained from empirical data is usually measured by the bootstrap probability (Pb) of interior branches of the tree. If the bootstrap probability is high for most branches, the tree is considered to be reliable. If some interior branches show relatively low bootstrap probabilities, we are not sure that the inferred tree is really reliable. Here, we propose another quantity measuring the reliability of the tree called the stability of a subtree. This quantity refers to the probability of obtaining a subtree (Ps) of an inferred tree obtained. We then show that if the tree is to be reliable, both Pb and Ps must be high. We also show that Ps is given by a bootstrap probability of the subtree with the closest outgroup sequence, and computer program RESTA for computing the Pb and Ps values will be presented. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Integrating Reliability Analysis with a Performance Tool

NASA Technical Reports Server (NTRS)

Nicol, David M.; Palumbo, Daniel L.; Ulrey, Michael

1995-01-01

A large number of commercial simulation tools support performance oriented studies of complex computer and communication systems. Reliability of these systems, when desired, must be obtained by remodeling the system in a different tool. This has obvious drawbacks: (1) substantial extra effort is required to create the reliability model; (2) through modeling error the reliability model may not reflect precisely the same system as the performance model; (3) as the performance model evolves one must continuously reevaluate the validity of assumptions made in that model. In this paper we describe an approach, and a tool that implements this approach, for integrating a reliability analysis engine into a production quality simulation based performance modeling tool, and for modeling within such an integrated tool. The integrated tool allows one to use the same modeling formalisms to conduct both performance and reliability studies. We describe how the reliability analysis engine is integrated into the performance tool, describe the extensions made to the performance tool to support the reliability analysis, and consider the tool's performance.

[Santa Claus is perceived as reliable and friendly: results of the Danish Christmas 2013 survey].

PubMed

Amin, Faisal Mohammad; West, Anders Sode; Jørgensen, Carina Sleiborg; Simonsen, Sofie Amalie; Lindberg, Ulrich; Tranum-Jensen, Jørgen; Hougaard, Anders

2013-12-02

Several studies have indicated that the population in general perceives doctors as reliable. In the present study perceptions of reliability and kindness attributed to another socially significant archetype, Santa Claus, have been comparatively examined in relation to the doctor. In all, 52 randomly chosen participants were shown a film, where a narrator dressed either as Santa Claus or as a doctor tells an identical story. Structured interviews were then used to assess the subjects' perceptions of reliability and kindness in relation to the narrator's appearance. We found a strong inclination for Santa Claus being perceived as friendlier than the doctor (p = 0.053). However, there was no significant difference in the perception of reliability between Santa Claus and the doctor (p = 0.524). The positive associations attributed to Santa Claus probably cause that he is perceived friendlier than the doctor who may be associated with more serious and unpleasant memories of illness and suffering. Surprisingly, and despite him being an imaginary person, Santa Claus was assessed as being as reliable as the doctor.

Reliability of performance of elite Olympic weightlifters.

PubMed

McGuigan, Michael R; Kane, Melissa K

2004-08-01

There are no published data on the reliability of competitive strength performance, even though it has a pronounced effect on athletes' medal prospects and the ability of coaches and athletes to identify factors that affect competitive performance. The purpose of this investigation was to analyze the reliability of elite olympic weightlifters over a series of international weightlifting meets. We obtained official results of international competitions over an 18-month period from 1999 until the 2000 Olympic Games at the International Weightlifting Federation website. The measure of reliability was the typical within-athlete variation, derived as the coefficient of variation (CV) by 2-way analysis of variance of log-transformed weights lifted for the snatch, clean and jerk, and total. The results of this analysis were (a) within-athlete variations were as follows: snatch, 2.7% (95% likely range, 2.4-3.2%); clean and jerk, 2.3% (1.7-3.6%); total weight lifted, 2.5% (2.2-2.9%); (b) men and women: the variation was higher for the women compared with the men in both snatch (ratio of CV, 1.4) and clean and jerk (ratio of CV, 1.5), and for the total weight lifted (ratio of CV, 1.3); and (c) the top 5 athletes were almost always more reliable than the bottom-half athletes. Recent work has shown that the smallest worthwhile performance is about half the within-athlete variation, so coaches and sport scientists should focus on enhancements of as little as 1.2% in total weight lifted for elite olympic weightlifters.

Can reliable sage-grouse lek counts be obtained using aerial infrared technology

USGS Publications Warehouse

Gillette, Gifford L.; Coates, Peter S.; Petersen, Steven; Romero, John P.

2013-01-01

More effective methods for counting greater sage-grouse (Centrocercus urophasianus) are needed to better assess population trends through enumeration or location of new leks. We describe an aerial infrared technique for conducting sage-grouse lek counts and compare this method with conventional ground-based lek count methods. During the breeding period in 2010 and 2011, we surveyed leks from fixed-winged aircraft using cryogenically cooled mid-wave infrared cameras and surveyed the same leks on the same day from the ground following a standard lek count protocol. We did not detect significant differences in lek counts between surveying techniques. These findings suggest that using a cryogenically cooled mid-wave infrared camera from an aerial platform to conduct lek surveys is an effective alternative technique to conventional ground-based methods, but further research is needed. We discuss multiple advantages to aerial infrared surveys, including counting in remote areas, representing greater spatial variation, and increasing the number of counted leks per season. Aerial infrared lek counts may be a valuable wildlife management tool that releases time and resources for other conservation efforts. Opportunities exist for wildlife professionals to refine and apply aerial infrared techniques to wildlife monitoring programs because of the increasing reliability and affordability of this technology.

Feasibility model of a high reliability five-year tape transport, Volume 1. [development, performance, and test results

NASA Technical Reports Server (NTRS)

Eshleman, R. L.; Meyers, A. P.; Davidson, W. A.; Gortowski, R. C.; Anderson, M. E.

1973-01-01

The development, performance, and test results for the spaceborne magnetic tape transport are discussed. An analytical model of the tape transport was used to optimize its conceptual design. Each of the subsystems was subjected to reliability analyses which included structural integrity, maintenance of system performance within acceptable bounds, and avoidance of fatigue failure. These subsystems were also compared with each other in order to evaluate reliability characteristics. The transport uses no mechanical couplings. Four drive motors, one for each reel and one for each of two capstans, are used in a differential mode. There are two hybrid, spherical, cone tapered-crown rollers for tape guidance. Storage of the magnetic tape is provided by a reel assembly which includes the reel, a reel support structure and bearings, dust seals, and a dc drive motor. A summary of transport test results on tape guidance, flutter, and skew is provided.

Reliability of cystometrically obtained intravesical pressures in patients with neurogenic bladders.

PubMed

Hess, Marika J; Lim, Lance; Yalla, Subbarao V

2002-01-01

Urodynamic studies in patients with neurogenic bladder detect and categorize neurourodynamic states, identify the risk for urologic sequelae, and determine the necessity for interventions. Because urodynamic studies serves as a prognostic indicator and guides patient management, pressure measurements during the study must accurately represent bladder function under physiologic conditions. Because nonphysiologic bladder filling used during conventional urodynamic studies may alter the bladder's accommodative properties, we studied how closely the intravesical pressures obtained before filling cystometry resembled those obtained during the filling phase of the cystometrogram. Twenty-two patients (21 men, 1 woman) with neurogenic bladders underwent standard urodynamic studies. A 16F triple-lumen catheter was inserted into the bladder, and the intravesical pressures were recorded (physiologic volume-specific pressures, PVSP). After emptying the bladder, an equal volume of normal saline solution was reinfused, and the pressures were recorded again (cystometric volume-specific pressure, CVSP). All patients underwent routine fluoroscopically assisted urodynamic testing. The PVSP and the CVSP were compared using the Wilcoxon signed ranks test. P value of .05 was significant. The mean PVSP was 14.5 cmH2O (range, 4-42 cmH2O) and mean CVSP was 20.6 cmH2O (range, 6-70 cmH2O). The CVSP was significantly higher than the PVSP (P = .01). Filling pressures during cystometry (CVSP) were significantly higher than the pressures measured at rest (PVSP). This study also suggests a strong correlation between PVSP and CVSP.

Reliability based design of the primary structure of oil tankers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casella, G.; Dogliani, M.; Guedes Soares, C.

1996-12-31

The present paper describes the reliability analysis carried out for two oil tanker-ships having comparable dimensions but different design. The scope of the analysis was to derive indications on the value of the reliability index obtained for existing, typical and well designed oil tankers, as well as to apply the tentative rule checking formulation developed within the CEC-funded SHIPREL Project. The checking formula was adopted to redesign the midships section of one of the considered ships, upgrading her in order to meet the target failure probability considered in the rule development process. The resulting structure, in view of an upgradingmore » of the steel grade in the central part of the deck, lead to a convenient reliability level. The results of the analysis clearly showed that a large scatter exists presently in the design safety levels of ships, even when the Classification Societies` unified requirements are satisfied. A reliability based approach for the calibration of the rules for the global strength of ships is therefore proposed, in order to assist designers and Classification Societies in the process of producing ships which are more optimized, with respect to ensured safety levels. Based on the work reported in the paper, the feasibility and usefulness of a reliability based approach in the development of ship longitudinal strength requirements has been demonstrated.« less

Reliability optimization design of the gear modification coefficient based on the meshing stiffness

NASA Astrophysics Data System (ADS)

Wang, Qianqian; Wang, Hui

2018-04-01

Since the time varying meshing stiffness of gear system is the key factor affecting gear vibration, it is important to design the meshing stiffness to reduce vibration. Based on the effect of gear modification coefficient on the meshing stiffness, considering the random parameters, reliability optimization design of the gear modification is researched. The dimension reduction and point estimation method is used to estimate the moment of the limit state function, and the reliability is obtained by the forth moment method. The cooperation of the dynamic amplitude results before and after optimization indicates that the research is useful for the reduction of vibration and noise and the improvement of the reliability.

Rollover risk prediction of heavy vehicles by reliability index and empirical modelling

NASA Astrophysics Data System (ADS)

Sellami, Yamine; Imine, Hocine; Boubezoul, Abderrahmane; Cadiou, Jean-Charles

2018-03-01

This paper focuses on a combination of a reliability-based approach and an empirical modelling approach for rollover risk assessment of heavy vehicles. A reliability-based warning system is developed to alert the driver to a potential rollover before entering into a bend. The idea behind the proposed methodology is to estimate the rollover risk by the probability that the vehicle load transfer ratio (LTR) exceeds a critical threshold. Accordingly, a so-called reliability index may be used as a measure to assess the vehicle safe functioning. In the reliability method, computing the maximum of LTR requires to predict the vehicle dynamics over the bend which can be in some cases an intractable problem or time-consuming. With the aim of improving the reliability computation time, an empirical model is developed to substitute the vehicle dynamics and rollover models. This is done by using the SVM (Support Vector Machines) algorithm. The preliminary obtained results demonstrate the effectiveness of the proposed approach.

Dynamic decision-making for reliability and maintenance analysis of manufacturing systems based on failure effects

NASA Astrophysics Data System (ADS)

Zhang, Ding; Zhang, Yingjie

2017-09-01

A framework for reliability and maintenance analysis of job shop manufacturing systems is proposed in this paper. An efficient preventive maintenance (PM) policy in terms of failure effects analysis (FEA) is proposed. Subsequently, reliability evaluation and component importance measure based on FEA are performed under the PM policy. A job shop manufacturing system is applied to validate the reliability evaluation and dynamic maintenance policy. Obtained results are compared with existed methods and the effectiveness is validated. Some vague understandings for issues such as network modelling, vulnerabilities identification, the evaluation criteria of repairable systems, as well as PM policy during manufacturing system reliability analysis are elaborated. This framework can help for reliability optimisation and rational maintenance resources allocation of job shop manufacturing systems.

Reliability and validity: Part II.

PubMed

Davis, Debora Winders

2004-01-01

Determining measurement reliability and validity involves complex processes. There is usually room for argument about most instruments. It is important that the researcher clearly describes the processes upon which she made the decision to use a particular instrument, and presents the evidence available showing that the instrument is reliable and valid for the current purposes. In some cases, the researcher may need to conduct pilot studies to obtain evidence upon which to decide whether the instrument is valid for a new population or a different setting. In all cases, the researcher must present a clear and complete explanation for the choices, she has made regarding reliability and validity. The consumer must then judge the degree to which the researcher has provided adequate and theoretically sound rationale. Although I have tried to touch on most of the important concepts related to measurement reliability and validity, it is beyond the scope of this column to be exhaustive. There are textbooks devoted entirely to specific measurement issues if readers require more in-depth knowledge.

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

NASA Astrophysics Data System (ADS)

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.

Results obtained with a low cost software-based audiometer for hearing screening.

PubMed

Ferrari, Deborah Viviane; Lopez, Esteban Alejandro; Lopes, Andrea Cintra; Aiello, Camila Piccini; Jokura, Pricila Reis

2013-07-01

 The implementation of hearing screening programs can be facilitated by reducing operating costs, including the cost of equipment. The Telessaúde (TS) audiometer is a low-cost, software-based, and easy-to-use piece of equipment for conducting audiometric screening.  To evaluate the TS audiometer for conducting audiometric screening.  A prospective randomized study was performed. Sixty subjects, divided into those who did not have (group A, n = 30) and those who had otologic complaints (group B, n = 30), underwent audiometric screening with conventional and TS audiometers in a randomized order. Pure tones at 25 dB HL were presented at frequencies of 500, 1000, 2000, and 4000 Hz. A "fail" result was considered when the individual failed to respond to at least one of the stimuli. Pure-tone audiometry was also performed on all participants. The concordance of the results of screening with both audiometers was evaluated. The sensitivity, specificity, and positive and negative predictive values of screening with the TS audiometer were calculated.  For group A, 100% of the ears tested passed the screening. For group B, "pass" results were obtained in 34.2% (TS) and 38.3% (conventional) of the ears tested. The agreement between procedures (TS vs. conventional) ranged from 93% to 98%. For group B, screening with the TS audiometer showed 95.5% sensitivity, 90.4% sensitivity, and positive and negative predictive values equal to 94.9% and 91.5%, respectively.  The results of the TS audiometer were similar to those obtained with the conventional audiometer, indicating that the TS audiometer can be used for audiometric screening.

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

PubMed

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.

How reliable are Functional Movement Screening scores? A systematic review of rater reliability.

PubMed

Moran, Robert W; Schneiders, Anthony G; Major, Katherine M; Sullivan, S John

2016-05-01

Several physical assessment protocols to identify intrinsic risk factors for injury aetiology related to movement quality have been described. The Functional Movement Screen (FMS) is a standardised, field-expedient test battery intended to assess movement quality and has been used clinically in preparticipation screening and in sports injury research. To critically appraise and summarise research investigating the reliability of scores obtained using the FMS battery. Systematic literature review. Systematic search of Google Scholar, Scopus (including ScienceDirect and PubMed), EBSCO (including Academic Search Complete, AMED, CINAHL, Health Source: Nursing/Academic Edition), MEDLINE and SPORTDiscus. Studies meeting eligibility criteria were assessed by 2 reviewers for risk of bias using the Quality Appraisal of Reliability Studies checklist. Overall quality of evidence was determined using van Tulder's levels of evidence approach. 12 studies were appraised. Overall, there was a 'moderate' level of evidence in favour of 'acceptable' (intraclass correlation coefficient ≥0.6) inter-rater and intra-rater reliability for composite scores derived from live scoring. For inter-rater reliability of composite scores derived from video recordings there was 'conflicting' evidence, and 'limited' evidence for intra-rater reliability. For inter-rater reliability based on live scoring of individual subtests there was 'moderate' evidence of 'acceptable' reliability (κ≥0.4) for 4 subtests (Deep Squat, Shoulder Mobility, Active Straight-leg Raise, Trunk Stability Push-up) and 'conflicting' evidence for the remaining 3 (Hurdle Step, In-line Lunge, Rotary Stability). This review found 'moderate' evidence that raters can achieve acceptable levels of inter-rater and intra-rater reliability of composite FMS scores when using live ratings. Overall, there were few high-quality studies, and the quality of several studies was impacted by poor study reporting particularly in relation to

Comparison of visual field test results obtained through Humphrey matrix frequency doubling technology perimetry versus standard automated perimetry in healthy children.

PubMed

Kocabeyoglu, Sibel; Uzun, Salih; Mocan, Mehmet Cem; Bozkurt, Banu; Irkec, Murat; Orhan, Mehmet

2013-10-01

The aim of this study was to compare the visual field test results in healthy children obtained via the Humphrey matrix 24-2 threshold program and standard automated perimetry (SAP) using the Swedish interactive threshold algorithm (SITA)-Standard 24-2 test. This prospective study included 55 healthy children without ocular or systemic disorders who underwent both SAP and frequency doubling technology (FDT) perimetry visual field testing. Visual field test reliability indices, test duration, global indices (mean deviation [MD], and pattern standard deviation [PSD]) were compared between the 2 tests using the Wilcoxon signed-rank test and paired t-test. The performance of the Humphrey field analyzer (HFA) 24-2 SITA-standard and frequency-doubling technology Matrix 24-2 tests between genders were compared with Mann-Whitney U-test. Fifty-five healthy children with a mean age of 12.2 ± 1.9 years (range from 8 years to 16 years) were included in this prospective study. The test durations of SAP and FDT were similar (5.2 ± 0.5 and 5.1 ± 0.2 min, respectively, P = 0.651). MD and the PSD values obtained via FDT Matrix were significantly higher than those obtained via SAP (P < 0.001), and fixation losses and false negative errors were significantly less with SAP (P < 0.05). A weak positive correlation between the two tests in terms of MD (r = 0.352, P = 0.008) and PSD (r = 0.329, P = 0.014) was observed. Children were able to complete both the visual test algorithms successfully within 6 min. However, SAP testing appears to be associated with less depression of the visual field indices of healthy children. FDT Matrix and SAP should not be used interchangeably in the follow-up of children.

Stirling Convertor Fasteners Reliability Quantification

NASA Technical Reports Server (NTRS)

Shah, Ashwin R.; Korovaichuk, Igor; Kovacevich, Tiodor; Schreiber, Jeffrey G.

2006-01-01

Onboard Radioisotope Power Systems (RPS) being developed for NASA s deep-space science and exploration missions require reliable operation for up to 14 years and beyond. Stirling power conversion is a candidate for use in an RPS because it offers a multifold increase in the conversion efficiency of heat to electric power and reduced inventory of radioactive material. Structural fasteners are responsible to maintain structural integrity of the Stirling power convertor, which is critical to ensure reliable performance during the entire mission. Design of fasteners involve variables related to the fabrication, manufacturing, behavior of fasteners and joining parts material, structural geometry of the joining components, size and spacing of fasteners, mission loads, boundary conditions, etc. These variables have inherent uncertainties, which need to be accounted for in the reliability assessment. This paper describes these uncertainties along with a methodology to quantify the reliability, and provides results of the analysis in terms of quantified reliability and sensitivity of Stirling power conversion reliability to the design variables. Quantification of the reliability includes both structural and functional aspects of the joining components. Based on the results, the paper also describes guidelines to improve the reliability and verification testing.

Software development predictors, error analysis, reliability models and software metric analysis

NASA Technical Reports Server (NTRS)

Basili, Victor

1983-01-01

The use of dynamic characteristics as predictors for software development was studied. It was found that there are some significant factors that could be useful as predictors. From a study on software errors and complexity, it was shown that meaningful results can be obtained which allow insight into software traits and the environment in which it is developed. Reliability models were studied. The research included the field of program testing because the validity of some reliability models depends on the answers to some unanswered questions about testing. In studying software metrics, data collected from seven software engineering laboratory (FORTRAN) projects were examined and three effort reporting accuracy checks were applied to demonstrate the need to validate a data base. Results are discussed.

Reliability and Agreement in Student Ratings of the Class Environment

ERIC Educational Resources Information Center

Nelson, Peter M.; Christ, Theodore J.

2016-01-01

The current study estimated the reliability and agreement of student ratings of the classroom environment obtained using the Responsive Environmental Assessment for Classroom Teaching (REACT; Christ, Nelson, & Demers, 2012; Nelson, Demers, & Christ, 2014). Coefficient alpha, class-level reliability, and class agreement indices were…

Calculating system reliability with SRFYDO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morzinski, Jerome; Anderson - Cook, Christine M; Klamann, Richard M

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 themore » 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.« less

Determination of Turboprop Reduction Gearbox System Fatigue Life and Reliability

NASA Technical Reports Server (NTRS)

Zaretsky, Erwin V.; Lewicki, David G.; Savage, Michael; Vlcek, Brian L.

2007-01-01

Two computational models to determine the fatigue life and reliability of a commercial turboprop gearbox are compared with each other and with field data. These models are (1) Monte Carlo simulation of randomly selected lives of individual bearings and gears comprising the system and (2) two-parameter Weibull distribution function for bearings and gears comprising the system using strict-series system reliability to combine the calculated individual component lives in the gearbox. The Monte Carlo simulation included the virtual testing of 744,450 gearboxes. Two sets of field data were obtained from 64 gearboxes that were first-run to removal for cause, were refurbished and placed back in service, and then were second-run until removal for cause. A series of equations were empirically developed from the Monte Carlo simulation to determine the statistical variation in predicted life and Weibull slope as a function of the number of gearboxes failed. The resultant L(sub 10) life from the field data was 5,627 hr. From strict-series system reliability, the predicted L(sub 10) life was 774 hr. From the Monte Carlo simulation, the median value for the L(sub 10) gearbox lives equaled 757 hr. Half of the gearbox L(sub 10) lives will be less than this value and the other half more. The resultant L(sub 10) life of the second-run (refurbished) gearboxes was 1,334 hr. The apparent load-life exponent p for the roller bearings is 5.2. Were the bearing lives to be recalculated with a load-life exponent p equal to 5.2, the predicted L(sub 10) life of the gearbox would be equal to the actual life obtained in the field. The component failure distribution of the gearbox from the Monte Carlo simulation was nearly identical to that using the strict-series system reliability analysis, proving the compatibility of these methods.

Epitaxial nickel disilicide with low resistivity and excellent reliability.

PubMed

Hsin, Cheng-Lun; Deng, Shiu-Sheng

2016-02-12

Ultra-thin epitaxial NiSi2 was formed, and its structure was examined by electron microscopy and x-ray diffraction. Compared with previous reports, the measured resistivity of the epitaxial NiSi2 was unprecedentedly low, reaching 7 μΩ cm in the experimental results and up to 14.93 μΩ cm after modification. The reliability, which was investigated under different temperatures and current densities to understand its electronic characteristics, was 1.5 times better than that of the conventional polycrystalline counterpart. Black's equation and the measured mean-time-to-failure (MTTF) were used to obtain the reliability characteristics of epitaxial and poly-NiSi2. Confidence intervals at 95% for each MTTF confirmed the single failure mode. The electromigration phenomenon was observed to be the failure mechanism. Our results provide evidence that epitaxial NiSi2 is a promising contact material for future electronics.

Epitaxial nickel disilicide with low resistivity and excellent reliability

NASA Astrophysics Data System (ADS)

Hsin, Cheng-Lun; Deng, Shiu-Sheng

2016-02-01

Ultra-thin epitaxial NiSi2 was formed, and its structure was examined by electron microscopy and x-ray diffraction. Compared with previous reports, the measured resistivity of the epitaxial NiSi2 was unprecedentedly low, reaching 7 μΩ cm in the experimental results and up to 14.93 μΩ cm after modification. The reliability, which was investigated under different temperatures and current densities to understand its electronic characteristics, was 1.5 times better than that of the conventional polycrystalline counterpart. Black’s equation and the measured mean-time-to-failure (MTTF) were used to obtain the reliability characteristics of epitaxial and poly-NiSi2. Confidence intervals at 95% for each MTTF confirmed the single failure mode. The electromigration phenomenon was observed to be the failure mechanism. Our results provide evidence that epitaxial NiSi2 is a promising contact material for future electronics.

Reliability approach to rotating-component design. [fatigue life and stress concentration

NASA Technical Reports Server (NTRS)

Kececioglu, D. B.; Lalli, V. R.

1975-01-01

A probabilistic methodology for designing rotating mechanical components using reliability to relate stress to strength is explained. The experimental test machines and data obtained for steel to verify this methodology are described. A sample mechanical rotating component design problem is solved by comparing a deterministic design method with the new design-by reliability approach. The new method shows that a smaller size and weight can be obtained for specified rotating shaft life and reliability, and uses the statistical distortion-energy theory with statistical fatigue diagrams for optimum shaft design. Statistical methods are presented for (1) determining strength distributions for steel experimentally, (2) determining a failure theory for stress variations in a rotating shaft subjected to reversed bending and steady torque, and (3) relating strength to stress by reliability.

The Use of Invariance and Bootstrap Procedures as a Method to Establish the Reliability of Research Results.

ERIC Educational Resources Information Center

Sandler, Andrew B.

Statistical significance is misused in educational and psychological research when it is applied as a method to establish the reliability of research results. Other techniques have been developed which can be correctly utilized to establish the generalizability of findings. Methods that do provide such estimates are known as invariance or…

Reliability of In Vitro Methods used to Measure Intrinsic Clearance of Hydrophobic Organic Chemicals by Rainbow Trout: Results of an International Ring Trial.

PubMed

Nichols, John; Fay, Kellie; Bernhard, Mary Jo; Bischof, Ina; Davis, John; Halder, Marlies; Hu, Jing; Johanning, Karla; Laue, Heike; Nabb, Diane; Schlechtriem, Christian; Segner, Helmut; Swintek, Joe; Weeks, John; Embry, Michelle

2018-05-14

In vitro assays are widely employed to obtain intrinsic clearance estimates used in toxicokinetic modeling efforts. However, the reliability of these methods is seldom reported. Here we describe the results of an international ring trial designed to evaluate two in vitro assays used to measure intrinsic clearance in rainbow trout. An important application of these assays is to predict the effect of biotransformation on chemical bioaccumulation. Six laboratories performed substrate depletion experiments with cyclohexyl salicylate, fenthion, 4-n-nonylphenol, deltamethrin, methoxychlor, and pyrene using cryopreserved hepatocytes and liver S9 fractions from trout. Variability within and among laboratories was characterized as the percent coefficient of variation (CV) in measured in vitro intrinsic clearance rates (CLIN VITRO, INT; ml/h/mg protein or 106 cells) for each chemical and test system. Mean intra-laboratory CVs for each test chemical averaged 18.9% for hepatocytes and 14.1% for S9 fractions, while inter-laboratory CVs (all chemicals and all tests) averaged 30.1% for hepatocytes and 22.4% for S9 fractions. When CLIN VITRO, INT values were extrapolated to in vivo intrinsic clearance estimates (CLIN VIVO,INT; L/d/kg fish), both assays yielded similar levels of activity (< 4-fold difference for all chemicals). Hepatic clearance rates (CLH; L/d/kg fish) calculated using data from both assays exhibited even better agreement. These findings show that both assays are highly reliable and suggest that either may be used to inform chemical bioaccumulation assessments for fish. This study highlights several issues related to the demonstration of assay reliability and may provide a template for evaluating other in vitro biotransformation assays.

Key Reliability Drivers of Liquid Propulsion Engines and A Reliability Model for Sensitivity Analysis

NASA Technical Reports Server (NTRS)

Huang, Zhao-Feng; Fint, Jeffry A.; Kuck, Frederick M.

2005-01-01

This paper is to address the in-flight reliability of a liquid propulsion engine system for a launch vehicle. We first establish a comprehensive list of system and sub-system reliability drivers for any liquid propulsion engine system. We then build a reliability model to parametrically analyze the impact of some reliability parameters. We present sensitivity analysis results for a selected subset of the key reliability drivers using the model. Reliability drivers identified include: number of engines for the liquid propulsion stage, single engine total reliability, engine operation duration, engine thrust size, reusability, engine de-rating or up-rating, engine-out design (including engine-out switching reliability, catastrophic fraction, preventable failure fraction, unnecessary shutdown fraction), propellant specific hazards, engine start and cutoff transient hazards, engine combustion cycles, vehicle and engine interface and interaction hazards, engine health management system, engine modification, engine ground start hold down with launch commit criteria, engine altitude start (1 in. start), Multiple altitude restart (less than 1 restart), component, subsystem and system design, manufacturing/ground operation support/pre and post flight check outs and inspection, extensiveness of the development program. We present some sensitivity analysis results for the following subset of the drivers: number of engines for the propulsion stage, single engine total reliability, engine operation duration, engine de-rating or up-rating requirements, engine-out design, catastrophic fraction, preventable failure fraction, unnecessary shutdown fraction, and engine health management system implementation (basic redlines and more advanced health management systems).

Reliability of visual and instrumental color matching.

PubMed

Igiel, Christopher; Lehmann, Karl Martin; Ghinea, Razvan; Weyhrauch, Michael; Hangx, Ysbrand; Scheller, Herbert; Paravina, Rade D

2017-09-01

The aim of this investigation was to evaluate intra-rater and inter-rater reliability of visual and instrumental shade matching. Forty individuals with normal color perception participated in this study. The right maxillary central incisor of a teaching model was prepared and restored with 10 feldspathic all-ceramic crowns of different shades. A shade matching session consisted of the observer (rater) visually selecting the best match by using VITA classical A1-D4 (VC) and VITA Toothguide 3D Master (3D) shade guides and the VITA Easyshade Advance intraoral spectrophotometer (ES) to obtain both VC and 3D matches. Three shade matching sessions were held with 4 to 6 weeks between sessions. Intra-rater reliability was assessed based on the percentage of agreement for the three sessions for the same observer, whereas the inter-rater reliability was calculated as mean percentage of agreement between different observers. The Fleiss' Kappa statistical analysis was used to evaluate visual inter-rater reliability. The mean intra-rater reliability for the visual shade selection was 64(11) for VC and 48(10) for 3D. The corresponding ES values were 96(4) for both VC and 3D. The percentages of observers who matched the same shade with VC and 3D were 55(10) and 43(12), respectively, while corresponding ES values were 88(8) for VC and 92(4) for 3D. The results for visual shade matching exhibited a high to moderate level of inconsistency for both intra-rater and inter-rater comparisons. The VITA Easyshade Advance intraoral spectrophotometer exhibited significantly better reliability compared with visual shade selection. This study evaluates the ability of observers to consistently match the same shade visually and with a dental spectrophotometer in different sessions. The intra-rater and inter-rater reliability (agreement of repeated shade matching) of visual and instrumental tooth color matching strongly suggest the use of color matching instruments as a supplementary tool in

Stroke Impact Scale 3.0: Reliability and Validity Evaluation of the Korean Version

PubMed Central

2017-01-01

Objective To establish the reliability and validity the Korean version of the Stroke Impact Scale (K-SIS) 3.0. Methods A total of 70 post-stroke patients were enrolled. All subjects were evaluated for general characteristics, Mini-Mental State Examination (MMSE), the National Institutes of Health Stroke Scale (NIHSS), Modified Barthel Index, Hospital Anxiety and Depression Scale (HADS). The SF-36 and K-SIS 3.0 assessed their health-related quality of life. Statistical analysis after evaluation, determined the reliability and validity of the K-SIS 3.0. Results A total of 70 patients (mean age, 54.97 years) participated in this study. Internal consistency of the SIS 3.0 (Cronbach's alpha) was obtained, and all domains had good co-efficiency, with threshold above 0.70. Test-retest reliability of SIS 3.0 required correlation (Spearman's rho) of the same domain scores obtained on the first and second assessments. Results were above 0.5, with the exception of social participation and mobility. Concurrent validity of K-SIS 3.0 was assessed using the SF-36, and other scales with the same or similar domains. Each domain of K-SIS 3.0 had a positive correlation with corresponding similar domain of SF-36 and other scales (HADS, MMSE, and NIHSS). Conclusion The newly developed K-SIS 3.0 showed high inter-intra reliability and test-retest reliabilities, together with high concurrent validity with the original and various other scales, for patients with stroke. K-SIS 3.0 can therefore be used for stroke patients, to assess their health-related quality of life and treatment efficacy. PMID:28758075

RELIABILITY AND VALIDITY OF SUBJECTIVE ASSESSMENT OF LUMBAR LORDOSIS IN CONVENTIONAL RADIOGRAPHY.

PubMed

Ruhinda, E; Byanyima, R K; Mugerwa, H

2014-10-01

Reliability and validity studies of different lumbar curvature analysis and measurement techniques have been documented however there is limited literature on the reliability and validity of subjective visual analysis. Radiological assessment of lumbar lordotic curve aids in early diagnosis of conditions even before neurologic changes set in. To ascertain the level of reliability and validity of subjective assessment of lumbar lordosis in conventional radiography. A blinded, repeated-measures diagnostic test was carried out on lumbar spine x-ray radiographs. Radiology Department at Joint Clinical Research Centre (JCRC), Mengo-Kampala-Uganda. Seventy (70) lateral lumbar x-ray films were used for this study and were obtained from the archive of JCRC radiology department at Butikiro house, Mengo-Kampala. Poor observer agreement, both inter- and intra-observer, with kappa values of 0.16 was found. Inter-observer agreement was poorer than intra-observer agreement. Kappa values significantly rose when the lumbar lordosis was clustered into four categories without grading each abnormality. The results confirm that subjective assessment of lumbar lordosis has low reliability and validity. Film quality has limited influence on the observer reliability. This study further shows that fewer scale categories of lordosis abnormalities produce better observer reliability.

[A systematic social observation tool: methods and results of inter-rater reliability].

PubMed

Freitas, Eulilian Dias de; Camargos, Vitor Passos; Xavier, César Coelho; Caiaffa, Waleska Teixeira; Proietti, Fernando Augusto

2013-10-01

Systematic social observation has been used as a health research methodology for collecting information from the neighborhood physical and social environment. The objectives of this article were to describe the operationalization of direct observation of the physical and social environment in urban areas and to evaluate the instrument's reliability. The systematic social observation instrument was designed to collect information in several domains. A total of 1,306 street segments belonging to 149 different neighborhoods in Belo Horizonte, Minas Gerais, Brazil, were observed. For the reliability study, 149 segments (1 per neighborhood) were re-audited, and Fleiss kappa was used to access inter-rater agreement. Mean agreement was 0.57 (SD = 0.24); 53% had substantial or almost perfect agreement, and 20.4%, moderate agreement. The instrument appears to be appropriate for observing neighborhood characteristics that are not time-dependent, especially urban services, property characterization, pedestrian environment, and security.

WHO Study on the reliability and validity of the alcohol and drug use disorder instruments: overview of methods and results.

PubMed

Ustün, B; Compton, W; Mager, D; Babor, T; Baiyewu, O; Chatterji, S; Cottler, L; Göğüş, A; Mavreas, V; Peters, L; Pull, C; Saunders, J; Smeets, R; Stipec, M R; Vrasti, R; Hasin, D; Room, R; Van den Brink, W; Regier, D; Blaine, J; Grant, B F; Sartorius, N

1997-09-25

The WHO Study on the reliability and validity of the alcohol and drug use disorder instruments in an international study which has taken place in centres in ten countries, aiming to test the reliability and validity of three diagnostic instruments for alcohol and drug use disorders: the Composite International Diagnostic Interview (CIDI), the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) and a special version of the Alcohol Use Disorder and Associated Disabilities Interview schedule-alcohol/drug-revised (AUDADIS-ADR). The purpose of the reliability and validity (R&V) study is to further develop the alcohol and drug sections of these instruments so that a range of substance-related diagnoses can be made in a systematic, consistent, and reliable way. The study focuses on new criteria proposed in the tenth revision of the International Classification of Diseases (ICD-10) and the fourth revision of the diagnostic and statistical manual of mental disorders (DSM-IV) for dependence, harmful use and abuse categories for alcohol and psychoactive substance use disorders. A systematic study including a scientifically rigorous measure of reliability (i.e. 1 week test-retest reliability) and validity (i.e. comparison between clinical and non-clinical measures) has been undertaken. Results have yielded useful information on reliability and validity of these instruments at diagnosis, criteria and question level. Overall the diagnostic concordance coefficients (kappa, kappa) were very good for dependence disorders (0.7-0.9), but were somewhat lower for the abuse and harmful use categories. The comparisons among instruments and independent clinical evaluations and debriefing interviews gave important information about possible sources of unreliability, and provided useful clues on the applicability and consistency of nosological concepts across cultures.

Reliability Stress-Strength Models for Dependent Observations with Applications in Clinical Trials

NASA Technical Reports Server (NTRS)

Kushary, Debashis; Kulkarni, Pandurang M.

1995-01-01

We consider the applications of stress-strength models in studies involving clinical trials. When studying the effects and side effects of certain procedures (treatments), it is often the case that observations are correlated due to subject effect, repeated measurements and observing many characteristics simultaneously. We develop maximum likelihood estimator (MLE) and uniform minimum variance unbiased estimator (UMVUE) of the reliability which in clinical trial studies could be considered as the chances of increased side effects due to a particular procedure compared to another. The results developed apply to both univariate and multivariate situations. Also, for the univariate situations we develop simple to use lower confidence bounds for the reliability. Further, we consider the cases when both stress and strength constitute time dependent processes. We define the future reliability and obtain methods of constructing lower confidence bounds for this reliability. Finally, we conduct simulation studies to evaluate all the procedures developed and also to compare the MLE and the UMVUE.

Health search engine with e-document analysis for reliable search results.

PubMed

Gaudinat, Arnaud; Ruch, Patrick; Joubert, Michel; Uziel, Philippe; Strauss, Anne; Thonnet, Michèle; Baud, Robert; Spahni, Stéphane; Weber, Patrick; Bonal, Juan; Boyer, Celia; Fieschi, Marius; Geissbuhler, Antoine

2006-01-01

After a review of the existing practical solution available to the citizen to retrieve eHealth document, the paper describes an original specialized search engine WRAPIN. WRAPIN uses advanced cross lingual information retrieval technologies to check information quality by synthesizing medical concepts, conclusions and references contained in the health literature, to identify accurate, relevant sources. Thanks to MeSH terminology [1] (Medical Subject Headings from the U.S. National Library of Medicine) and advanced approaches such as conclusion extraction from structured document, reformulation of the query, WRAPIN offers to the user a privileged access to navigate through multilingual documents without language or medical prerequisites. The results of an evaluation conducted on the WRAPIN prototype show that results of the WRAPIN search engine are perceived as informative 65% (59% for a general-purpose search engine), reliable and trustworthy 72% (41% for the other engine) by users. But it leaves room for improvement such as the increase of database coverage, the explanation of the original functionalities and an audience adaptability. Thanks to evaluation outcomes, WRAPIN is now in exploitation on the HON web site (http://www.healthonnet.org), free of charge. Intended to the citizen it is a good alternative to general-purpose search engines when the user looks up trustworthy health and medical information or wants to check automatically a doubtful content of a Web page.

Reliability of Space-Shuttle Pressure Vessels with Random Batch Effects

NASA Technical Reports Server (NTRS)

Feiveson, Alan H.; Kulkarni, Pandurang M.

2000-01-01

In this article we revisit the problem of estimating the joint reliability against failure by stress rupture of a group of fiber-wrapped pressure vessels used on Space-Shuttle missions. The available test data were obtained from an experiment conducted at the U.S. Department of Energy Lawrence Livermore Laboratory (LLL) in which scaled-down vessels were subjected to life testing at four accelerated levels of pressure. We estimate the reliability assuming that both the Shuttle and LLL vessels were chosen at random in a two-stage process from an infinite population with spools of fiber as the primary sampling unit. Two main objectives of this work are: (1) to obtain practical estimates of reliability taking into account random spool effects and (2) to obtain a realistic assessment of estimation accuracy under the random model. Here, reliability is calculated in terms of a 'system' of 22 fiber-wrapped pressure vessels, taking into account typical pressures and exposure times experienced by Shuttle vessels. Comparisons are made with previous studies. The main conclusion of this study is that, although point estimates of reliability are still in the 'comfort zone,' it is advisable to plan for replacement of the pressure vessels well before the expected Lifetime of 100 missions per Shuttle Orbiter. Under a random-spool model, there is simply not enough information in the LLL data to provide reasonable assurance that such replacement would not be necessary.

Interformat reliability of digital psychiatric self-report questionnaires: a systematic review.

PubMed

Alfonsson, Sven; Maathz, Pernilla; Hursti, Timo

2014-12-03

Research on Internet-based interventions typically use digital versions of pen and paper self-report symptom scales. However, adaptation into the digital format could affect the psychometric properties of established self-report scales. Several studies have investigated differences between digital and pen and paper versions of instruments, but no systematic review of the results has yet been done. This review aims to assess the interformat reliability of self-report symptom scales used in digital or online psychotherapy research. Three databases (MEDLINE, Embase, and PsycINFO) were systematically reviewed for studies investigating the reliability between digital and pen and paper versions of psychiatric symptom scales. From a total of 1504 publications, 33 were included in the review, and interformat reliability of 40 different symptom scales was assessed. Significant differences in mean total scores between formats were found in 10 of 62 analyses. These differences were found in just a few studies, which indicates that the results were due to study effects and sample effects rather than unreliable instruments. The interformat reliability ranged from r=.35 to r=.99; however, the majority of instruments showed a strong correlation between format scores. The quality of the included studies varied, and several studies had insufficient power to detect small differences between formats. When digital versions of self-report symptom scales are compared to pen and paper versions, most scales show high interformat reliability. This supports the reliability of results obtained in psychotherapy research on the Internet and the comparability of the results to traditional psychotherapy research. There are, however, some instruments that consistently show low interformat reliability, suggesting that these conclusions cannot be generalized to all questionnaires. Most studies had at least some methodological issues with insufficient statistical power being the most common issue

Reliability and validity of quantifying absolute muscle hardness using ultrasound elastography.

PubMed

Chino, Kentaro; Akagi, Ryota; Dohi, Michiko; Fukashiro, Senshi; Takahashi, Hideyuki

2012-01-01

Muscle hardness is a mechanical property that represents transverse muscle stiffness. A quantitative method that uses ultrasound elastography for quantifying absolute human muscle hardness has been previously devised; however, its reliability and validity have not been completely verified. This study aimed to verify the reliability and validity of this quantitative method. The Young's moduli of seven tissue-mimicking materials (in vitro; Young's modulus range, 20-80 kPa; increments of 10 kPa) and the human medial gastrocnemius muscle (in vivo) were quantified using ultrasound elastography. On the basis of the strain/Young's modulus ratio of two reference materials, one hard and one soft (Young's moduli of 7 and 30 kPa, respectively), the Young's moduli of the tissue-mimicking materials and medial gastrocnemius muscle were calculated. The intra- and inter-investigator reliability of the method was confirmed on the basis of acceptably low coefficient of variations (≤6.9%) and substantially high intraclass correlation coefficients (≥0.77) obtained from all measurements. The correlation coefficient between the Young's moduli of the tissue-mimicking materials obtained using a mechanical method and ultrasound elastography was 0.996, which was equivalent to values previously obtained using magnetic resonance elastography. The Young's moduli of the medial gastrocnemius muscle obtained using ultrasound elastography were within the range of values previously obtained using magnetic resonance elastography. The reliability and validity of the quantitative method for measuring absolute muscle hardness using ultrasound elastography were thus verified.

Reliability Generalization: Exploring Variation of Reliability Coefficients of MMPI Clinical Scales Scores.

ERIC Educational Resources Information Center

Vacha-Haase, Tammi; Kogan, Lori R.; Tani, Crystal R.; Woodall, Renee A.

2001-01-01

Used reliability generalization to explore the variance of scores on 10 Minnesota Multiphasic Personality Inventory (MMPI) clinical scales drawing on 1,972 articles in the literature on the MMPI. Results highlight the premise that scores, not tests, are reliable or unreliable, and they show that study characteristics do influence scores on the…

Covariate-free and Covariate-dependent Reliability.

PubMed

Bentler, Peter M

2016-12-01

Classical test theory reliability coefficients are said to be population specific. Reliability generalization, a meta-analysis method, is the main procedure for evaluating the stability of reliability coefficients across populations. A new approach is developed to evaluate the degree of invariance of reliability coefficients to population characteristics. Factor or common variance of a reliability measure is partitioned into parts that are, and are not, influenced by control variables, resulting in a partition of reliability into a covariate-dependent and a covariate-free part. The approach can be implemented in a single sample and can be applied to a variety of reliability coefficients.

Results of the 2013 UT modeling benchmark obtained with models implemented in CIVA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toullelan, Gwénaël; Raillon, Raphaële; Chatillon, Sylvain

The 2013 Ultrasonic Testing (UT) modeling benchmark concerns direct echoes from side drilled holes (SDH), flat bottom holes (FBH) and corner echoes from backwall breaking artificial notches inspected with a matrix phased array probe. This communication presents the results obtained with the models implemented in the CIVA software: the pencilmodel is used to compute the field radiated by the probe, the Kirchhoff approximation is applied to predict the response of FBH and notches and the SOV (Separation Of Variables) model is used for the SDH responses. The comparison between simulated and experimental results are presented and discussed.

Comparison of results obtained with various sensors used to measure fluctuating quantities in jets.

NASA Technical Reports Server (NTRS)

Parthasarathy, S. P.; Massier, P. F.; Cuffel, R. F.

1973-01-01

An experimental investigation has been conducted to compare the results obtained with six different instruments that sense fluctuating quantities in free jets. These sensors are typical of those that have recently been used by various investigators who are engaged in experimental studies of jet noise. Intensity distributions and two-point correlations with space separation and time delay were obtained. The static pressure, density, and velocity fluctuations are well correlated over the entire cross section of the jet and the cross-correlations persist for several jet diameters along the flow direction. The eddies appear to be flattened in the flow direction by a ratio of 0.4.

The ventriloquist in periphery: impact of eccentricity-related reliability on audio-visual localization.

PubMed

Charbonneau, Geneviève; Véronneau, Marie; Boudrias-Fournier, Colin; Lepore, Franco; Collignon, Olivier

2013-10-28

The relative reliability of separate sensory estimates influences the way they are merged into a unified percept. We investigated how eccentricity-related changes in reliability of auditory and visual stimuli influence their integration across the entire frontal space. First, we surprisingly found that despite a strong decrease in auditory and visual unisensory localization abilities in periphery, the redundancy gain resulting from the congruent presentation of audio-visual targets was not affected by stimuli eccentricity. This result therefore contrasts with the common prediction that a reduction in sensory reliability necessarily induces an enhanced integrative gain. Second, we demonstrate that the visual capture of sounds observed with spatially incongruent audio-visual targets (ventriloquist effect) steadily decreases with eccentricity, paralleling a lowering of the relative reliability of unimodal visual over unimodal auditory stimuli in periphery. Moreover, at all eccentricities, the ventriloquist effect positively correlated with a weighted combination of the spatial resolution obtained in unisensory conditions. These findings support and extend the view that the localization of audio-visual stimuli relies on an optimal combination of auditory and visual information according to their respective spatial reliability. All together, these results evidence that the external spatial coordinates of multisensory events relative to an observer's body (e.g., eyes' or head's position) influence how this information is merged, and therefore determine the perceptual outcome.

Reliability-Based Design Optimization of a Composite Airframe Component

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Pai, Shantaram S.; Coroneos, Rula M.

2009-01-01

A stochastic design optimization methodology (SDO) has been developed to design components of an airframe structure that can be made of metallic and composite materials. The design is obtained as a function of the risk level, or reliability, p. The design method treats uncertainties in load, strength, and material properties as distribution functions, which are defined with mean values and standard deviations. A design constraint or a failure mode is specified as a function of reliability p. Solution to stochastic optimization yields the weight of a structure as a function of reliability p. Optimum weight versus reliability p traced out an inverted-S-shaped graph. The center of the inverted-S graph corresponded to 50 percent (p = 0.5) probability of success. A heavy design with weight approaching infinity could be produced for a near-zero rate of failure that corresponds to unity for reliability p (or p = 1). Weight can be reduced to a small value for the most failure-prone design with a reliability that approaches zero (p = 0). Reliability can be changed for different components of an airframe structure. For example, the landing gear can be designed for a very high reliability, whereas it can be reduced to a small extent for a raked wingtip. The SDO capability is obtained by combining three codes: (1) The MSC/Nastran code was the deterministic analysis tool, (2) The fast probabilistic integrator, or the FPI module of the NESSUS software, was the probabilistic calculator, and (3) NASA Glenn Research Center s optimization testbed CometBoards became the optimizer. The SDO capability requires a finite element structural model, a material model, a load model, and a design model. The stochastic optimization concept is illustrated considering an academic example and a real-life raked wingtip structure of the Boeing 767-400 extended range airliner made of metallic and composite materials.

Simplest chronoscope. III. Further comparisons between reaction times obtained by meterstick versus machine.

PubMed

Montare, Alberto

2013-06-01

The three classical Donders' reaction time (RT) tasks (simple, choice, and discriminative RTs) were employed to compare reaction time scores from college students obtained by use of Montare's simplest chronoscope (meterstick) methodology to scores obtained by use of a digital-readout multi-choice reaction timer (machine). Five hypotheses were tested. Simple RT, choice RT, and discriminative RT were faster when obtained by meterstick than by machine. The meterstick method showed higher reliability than the machine method and was less variable. The meterstick method of the simplest chronoscope may help to alleviate the longstanding problems of low reliability and high variability of reaction time performances; while at the same time producing faster performance on Donders' simple, choice and discriminative RT tasks than the machine method.

Reliability of ultrasound grading traditional score and new global OMERACT-EULAR score system (GLOESS): results from an inter- and intra-reading exercise by rheumatologists.

PubMed

Ventura-Ríos, Lucio; Hernández-Díaz, Cristina; Ferrusquia-Toríz, Diana; Cruz-Arenas, Esteban; Rodríguez-Henríquez, Pedro; Alvarez Del Castillo, Ana Laura; Campaña-Parra, Alfredo; Canul, Efrén; Guerrero Yeo, Gerardo; Mendoza-Ruiz, Juan Jorge; Pérez Cristóbal, Mario; Sicsik, Sandra; Silva Luna, Karina

2017-12-01

This study aims to test the reliability of ultrasound to graduate synovitis in static and video images, evaluating separately grayscale and power Doppler (PD), and combined. Thirteen trained rheumatologist ultrasonographers participated in two separate rounds reading 42 images, 15 static and 27 videos, of the 7-joint count [wrist, 2nd and 3rd metacarpophalangeal (MCP), 2nd and 3rd interphalangeal (IPP), 2nd and 5th metatarsophalangeal (MTP) joints]. The images were from six patients with rheumatoid arthritis, performed by one ultrasonographer. Synovitis definition was according to OMERACT. Scoring system in grayscale, PD separately, and combined (GLOESS-Global OMERACT-EULAR Score System) were reviewed before exercise. Reliability intra- and inter-reading was calculated with Cohen's kappa weighted, according to Landis and Koch. Kappa values for inter-reading were good to excellent. The minor kappa was for GLOESS in static images, and the highest was for the same scoring in videos (k 0.59 and 0.85, respectively). Excellent values were obtained for static PD in 5th MTP joint and for PD video in 2nd MTP joint. Results for GLOESS in general were good to moderate. Poor agreement was observed in 3rd MCP and 3rd IPP in all kinds of images. Intra-reading agreement were greater in grayscale and GLOESS in static images than in videos (k 0.86 vs. 0.77 and k 0.86 vs. 0.71, respectively), but PD was greater in videos than in static images (k 1.0 vs. 0.79). The reliability of the synovitis scoring through static images and videos is in general good to moderate when using grayscale and PD separately or combined.

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

PubMed Central

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

Reliability Measurement for Mixed Mode Failures of 33/11 Kilovolt Electric Power Distribution Stations

PubMed Central

Alwan, Faris M.; Baharum, Adam; Hassan, Geehan S.

2013-01-01

The reliability of the electrical distribution system is a contemporary research field due to diverse applications of electricity in everyday life and diverse industries. However a few research papers exist in literature. This paper proposes a methodology for assessing the reliability of 33/11 Kilovolt high-power stations based on average time between failures. The objective of this paper is to find the optimal fit for the failure data via time between failures. We determine the parameter estimation for all components of the station. We also estimate the reliability value of each component and the reliability value of the system as a whole. The best fitting distribution for the time between failures is a three parameter Dagum distribution with a scale parameter and shape parameters and . Our analysis reveals that the reliability value decreased by 38.2% in each 30 days. We believe that the current paper is the first to address this issue and its analysis. Thus, the results obtained in this research reflect its originality. We also suggest the practicality of using these results for power systems for both the maintenance of power systems models and preventive maintenance models. PMID:23936346

Testing the reliability of ice-cream cone model

NASA Astrophysics Data System (ADS)

Pan, Zonghao; Shen, Chenglong; Wang, Chuanbing; Liu, Kai; Xue, Xianghui; Wang, Yuming; Wang, Shui

2015-04-01

Coronal Mass Ejections (CME)'s properties are important to not only the physical scene itself but space-weather prediction. Several models (such as cone model, GCS model, and so on) have been raised to get rid of the projection effects within the properties observed by spacecraft. According to SOHO/ LASCO observations, we obtain the 'real' 3D parameters of all the FFHCMEs (front-side full halo Coronal Mass Ejections) within the 24th solar cycle till July 2012, by the ice-cream cone model. Considering that the method to obtain 3D parameters from the CME observations by multi-satellite and multi-angle has higher accuracy, we use the GCS model to obtain the real propagation parameters of these CMEs in 3D space and compare the results with which by ice-cream cone model. Then we could discuss the reliability of the ice-cream cone model.

Analysis shear wave velocity structure obtained from surface wave methods in Bornova, Izmir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pamuk, Eren, E-mail: eren.pamuk@deu.edu.tr; Akgün, Mustafa, E-mail: mustafa.akgun@deu.edu.tr; Özdağ, Özkan Cevdet, E-mail: cevdet.ozdag@deu.edu.tr

2016-04-18

Properties of the soil from the bedrock is necessary to describe accurately and reliably for the reduction of earthquake damage. Because seismic waves change their amplitude and frequency content owing to acoustic impedance difference between soil and bedrock. Firstly, shear wave velocity and depth information of layers on bedrock is needed to detect this changing. Shear wave velocity can be obtained using inversion of Rayleigh wave dispersion curves obtained from surface wave methods (MASW- the Multichannel Analysis of Surface Waves, ReMi-Refraction Microtremor, SPAC-Spatial Autocorrelation). While research depth is limeted in active source study, a passive source methods are utilized formore » deep depth which is not reached using active source methods. ReMi method is used to determine layer thickness and velocity up to 100 m using seismic refraction measurement systems.The research carried out up to desired depth depending on radius using SPAC which is utilized easily in conditions that district using of seismic studies in the city. Vs profiles which are required to calculate deformations in under static and dynamic loads can be obtained with high resolution using combining rayleigh wave dispersion curve obtained from active and passive source methods. In the this study, Surface waves data were collected using the measurements of MASW, ReMi and SPAC at the İzmir Bornova region. Dispersion curves obtained from surface wave methods were combined in wide frequency band and Vs-depth profiles were obtained using inversion. Reliability of the resulting soil profiles were provided by comparison with theoretical transfer function obtained from soil paremeters and observed soil transfer function from Nakamura technique and by examination of fitting between these functions. Vs values are changed between 200-830 m/s and engineering bedrock (Vs>760 m/s) depth is approximately 150 m.« less

Analysis of fatigue reliability for high temperature and high pressure multi-stage decompression control valve

NASA Astrophysics Data System (ADS)

Yu, Long; Xu, Juanjuan; Zhang, Lifang; Xu, Xiaogang

2018-03-01

Based on stress-strength interference theory to establish the reliability mathematical model for high temperature and high pressure multi-stage decompression control valve (HMDCV), and introduced to the temperature correction coefficient for revising material fatigue limit at high temperature. Reliability of key dangerous components and fatigue sensitivity curve of each component are calculated and analyzed by the means, which are analyzed the fatigue life of control valve and combined with reliability theory of control valve model. The impact proportion of each component on the control valve system fatigue failure was obtained. The results is shown that temperature correction factor makes the theoretical calculations of reliability more accurate, prediction life expectancy of main pressure parts accords with the technical requirements, and valve body and the sleeve have obvious influence on control system reliability, the stress concentration in key part of control valve can be reduced in the design process by improving structure.

Reliability of quantitative EEG (qEEG) measures and LORETA current source density at 30 days.

PubMed

Cannon, Rex L; Baldwin, Debora R; Shaw, Tiffany L; Diloreto, Dominic J; Phillips, Sherman M; Scruggs, Annie M; Riehl, Timothy C

2012-06-14

There is a growing interest for using quantitative EEG and LORETA current source density in clinical and research settings. Importantly, if these indices are to be employed in clinical settings then the reliability of these measures is of great concern. Neuroguide (Applied Neurosciences) is sophisticated software developed for the analyses of power, and connectivity measures of the EEG as well as LORETA current source density. To date there are relatively few data evaluating topographical EEG reliability contrasts for all 19 channels and no studies have evaluated reliability for LORETA calculations. We obtained 4 min eyes-closed and eyes-opened EEG recordings at 30-day intervals. The EEG was analyzed in Neuroguide and FFT power, coherence and phase was computed for traditional frequency bands (delta, theta, alpha and beta) and LORETA current source density was calculated in 1 Hz increments and summed for total power in eight regions of interest (ROI). In order to obtain a robust measure of reliability we utilized a random effects model with an absolute agreement definition. The results show very good reproducibility for total absolute power and coherence. Phase shows lower reliability coefficients. LORETA current source density shows very good reliability with an average 0.81 for ECB and 0.82 for EOB. Similarly, the eight regions of interest show good to very good agreement across time. Implications for future directions and use of qEEG and LORETA in clinical populations are discussed. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Reliability of capturing foot parameters using digital scanning and the neutral suspension casting technique

PubMed Central

2011-01-01

Background A clinical study was conducted to determine the intra and inter-rater reliability of digital scanning and the neutral suspension casting technique to measure six foot parameters. The neutral suspension casting technique is a commonly utilised method for obtaining a negative impression of the foot prior to orthotic fabrication. Digital scanning offers an alternative to the traditional plaster of Paris techniques. Methods Twenty one healthy participants volunteered to take part in the study. Six casts and six digital scans were obtained from each participant by two raters of differing clinical experience. The foot parameters chosen for investigation were cast length (mm), forefoot width (mm), rearfoot width (mm), medial arch height (mm), lateral arch height (mm) and forefoot to rearfoot alignment (degrees). Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) were calculated to determine the intra and inter-rater reliability. Measurement error was assessed through the calculation of the standard error of the measurement (SEM) and smallest real difference (SRD). Results ICC values for all foot parameters using digital scanning ranged between 0.81-0.99 for both intra and inter-rater reliability. For neutral suspension casting technique inter-rater reliability values ranged from 0.57-0.99 and intra-rater reliability values ranging from 0.36-0.99 for rater 1 and 0.49-0.99 for rater 2. Conclusions The findings of this study indicate that digital scanning is a reliable technique, irrespective of clinical experience, with reduced measurement variability in all foot parameters investigated when compared to neutral suspension casting. PMID:21375757

Reliability and Validity of Quantifying Absolute Muscle Hardness Using Ultrasound Elastography

PubMed Central

Chino, Kentaro; Akagi, Ryota; Dohi, Michiko; Fukashiro, Senshi; Takahashi, Hideyuki

2012-01-01

Muscle hardness is a mechanical property that represents transverse muscle stiffness. A quantitative method that uses ultrasound elastography for quantifying absolute human muscle hardness has been previously devised; however, its reliability and validity have not been completely verified. This study aimed to verify the reliability and validity of this quantitative method. The Young’s moduli of seven tissue-mimicking materials (in vitro; Young’s modulus range, 20–80 kPa; increments of 10 kPa) and the human medial gastrocnemius muscle (in vivo) were quantified using ultrasound elastography. On the basis of the strain/Young’s modulus ratio of two reference materials, one hard and one soft (Young’s moduli of 7 and 30 kPa, respectively), the Young’s moduli of the tissue-mimicking materials and medial gastrocnemius muscle were calculated. The intra- and inter-investigator reliability of the method was confirmed on the basis of acceptably low coefficient of variations (≤6.9%) and substantially high intraclass correlation coefficients (≥0.77) obtained from all measurements. The correlation coefficient between the Young’s moduli of the tissue-mimicking materials obtained using a mechanical method and ultrasound elastography was 0.996, which was equivalent to values previously obtained using magnetic resonance elastography. The Young’s moduli of the medial gastrocnemius muscle obtained using ultrasound elastography were within the range of values previously obtained using magnetic resonance elastography. The reliability and validity of the quantitative method for measuring absolute muscle hardness using ultrasound elastography were thus verified. PMID:23029231

Reliability Improvement in III-V Concentrator Solar Cells by Means of Perimeter Protection

NASA Astrophysics Data System (ADS)

González, José R.; Vázquez, Manuel; Núñez, Neftalí; Algora, Carlos; Espinet, Pilar

2010-10-01

This paper presents the evolution in the strategy to assess the reliability of III-V solar cells and a new thermal ageing test carried out over GaAs single junction solar cells at three different temperatures (130, 150 and 170° C). The perimeter of the solar cells has been protected with silicone, which seems to be an effective way of enhancing the reliability of the solar cells. A preliminary analysis of the results indicates a mean time to failure (MTTF) one order of magnitude larger than the one obtained in a previous thermal test with the perimeter uncoated.

Test-Retest Reliability of fMRI Brain Activity during Memory Encoding

PubMed Central

Brandt, David J.; Sommer, Jens; Krach, Sören; Bedenbender, Johannes; Kircher, Tilo; Paulus, Frieder M.; Jansen, Andreas

2013-01-01

The mechanisms underlying hemispheric specialization of memory are not completely understood. Functional magnetic resonance imaging (fMRI) can be used to develop and test models of hemispheric specialization. In particular for memory tasks however, the interpretation of fMRI results is often hampered by the low reliability of the data. In the present study we therefore analyzed the test-retest reliability of fMRI brain activation related to an implicit memory encoding task, with a particular focus on brain activity of the medial temporal lobe (MTL). Fifteen healthy subjects were scanned with fMRI on two sessions (average retest interval 35 days) using a commonly applied novelty encoding paradigm contrasting known and unknown stimuli. To assess brain lateralization, we used three different stimuli classes that differed in their verbalizability (words, scenes, fractals). Test-retest reliability of fMRI brain activation was assessed by an intraclass-correlation coefficient (ICC), describing the stability of inter-individual differences in the brain activation magnitude over time. We found as expected a left-lateralized brain activation network for the words paradigm, a bilateral network for the scenes paradigm, and predominantly right-hemispheric brain activation for the fractals paradigm. Although these networks were consistently activated in both sessions on the group level, across-subject reliabilities were only poor to fair (ICCs ≤ 0.45). Overall, the highest ICC values were obtained for the scenes paradigm, but only in strongly activated brain regions. In particular the reliability of brain activity of the MTL was poor for all paradigms. In conclusion, for novelty encoding paradigms the interpretation of fMRI results on a single subject level is hampered by its low reliability. More studies are needed to optimize the retest reliability of fMRI activation for memory tasks. PMID:24367338

The definition and evaluation of the skills required to obtain a patient's history of illness: the use of videotape recordings

PubMed Central

Anderson, J.; Dowling, M. A. C.; Day, J. L.; Pettingale, K. W.

1970-01-01

Videotape recording apparatus was used to make records of case histories obtained from patients by students and doctors. These records were studied in order to identify the skills required to obtain a patient's history of illness. Each skill was defined. A questionnaire was developed in order to assess these skills and three independent observers watched the records of eighteen students and completed a questionnaire for each. The results of this were analysed for reliability and reproducibility between examiners. Moderate reliability and reproducibility were demonstrated. The questionnaire appeared to be a valid method of assessment and was capable of providing significant discrimination between students for each skill. A components analysis suggested that the marks for each skill depend on an overall impression obtained by each examiner and this overall impression is influenced by different skills for each examiner. PMID:5488220

Reliability and Validity Assessment of a Linear Position Transducer

PubMed Central

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

2015-01-01

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

Software reliability models for critical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pham, H.; Pham, M.

This report presents the results of the first phase of the ongoing EG G Idaho, Inc. Software Reliability Research Program. The program is studying the existing software reliability models and proposes a state-of-the-art software reliability model that is relevant to the nuclear reactor control environment. This report consists of three parts: (1) summaries of the literature review of existing software reliability and fault tolerant software reliability models and their related issues, (2) proposed technique for software reliability enhancement, and (3) general discussion and future research. The development of this proposed state-of-the-art software reliability model will be performed in the secondmore » place. 407 refs., 4 figs., 2 tabs.« less

Software reliability models for critical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pham, H.; Pham, M.

This report presents the results of the first phase of the ongoing EG&G Idaho, Inc. Software Reliability Research Program. The program is studying the existing software reliability models and proposes a state-of-the-art software reliability model that is relevant to the nuclear reactor control environment. This report consists of three parts: (1) summaries of the literature review of existing software reliability and fault tolerant software reliability models and their related issues, (2) proposed technique for software reliability enhancement, and (3) general discussion and future research. The development of this proposed state-of-the-art software reliability model will be performed in the second place.more » 407 refs., 4 figs., 2 tabs.« less

Reliability apportionment approach for spacecraft solar array using fuzzy reasoning Petri net and fuzzy comprehensive evaluation

NASA Astrophysics Data System (ADS)

Wu, Jianing; Yan, Shaoze; Xie, Liyang; Gao, Peng

2012-07-01

The reliability apportionment of spacecraft solar array is of significant importance for spacecraft designers in the early stage of design. However, it is difficult to use the existing methods to resolve reliability apportionment problem because of the data insufficiency and the uncertainty of the relations among the components in the mechanical system. This paper proposes a new method which combines the fuzzy comprehensive evaluation with fuzzy reasoning Petri net (FRPN) to accomplish the reliability apportionment of the solar array. The proposed method extends the previous fuzzy methods and focuses on the characteristics of the subsystems and the intrinsic associations among the components. The analysis results show that the synchronization mechanism may obtain the highest reliability value and the solar panels and hinges may get the lowest reliability before design and manufacturing. Our developed method is of practical significance for the reliability apportionment of solar array where the design information has not been clearly identified, particularly in early stage of design.

SMART empirical approaches for predicting field performance of PV modules from results of reliability tests

NASA Astrophysics Data System (ADS)

Hardikar, Kedar Y.; Liu, Bill J. J.; Bheemreddy, Venkata

2016-09-01

Gaining an understanding of degradation mechanisms and their characterization are critical in developing relevant accelerated tests to ensure PV module performance warranty over a typical lifetime of 25 years. As newer technologies are adapted for PV, including new PV cell technologies, new packaging materials, and newer product designs, the availability of field data over extended periods of time for product performance assessment cannot be expected within the typical timeframe for business decisions. In this work, to enable product design decisions and product performance assessment for PV modules utilizing newer technologies, Simulation and Mechanism based Accelerated Reliability Testing (SMART) methodology and empirical approaches to predict field performance from accelerated test results are presented. The method is demonstrated for field life assessment of flexible PV modules based on degradation mechanisms observed in two accelerated tests, namely, Damp Heat and Thermal Cycling. The method is based on design of accelerated testing scheme with the intent to develop relevant acceleration factor models. The acceleration factor model is validated by extensive reliability testing under different conditions going beyond the established certification standards. Once the acceleration factor model is validated for the test matrix a modeling scheme is developed to predict field performance from results of accelerated testing for particular failure modes of interest. Further refinement of the model can continue as more field data becomes available. While the demonstration of the method in this work is for thin film flexible PV modules, the framework and methodology can be adapted to other PV products.

Using Riemannian geometry to obtain new results on Dikin and Karmarkar methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliveira, P.; Joao, X.; Piaui, T.

1994-12-31

We are motivated by a 1990 Karmarkar paper on Riemannian geometry and Interior Point Methods. In this talk we show 3 results. (1) Karmarkar direction can be derived from the Dikin one. This is obtained by constructing a certain Z(x) representation of the null space of the unitary simplex (e, x) = 1; then the projective direction is the image under Z(x) of the affine-scaling one, when it is restricted to that simplex. (2) Second order information on Dikin and Karmarkar methods. We establish computable Hessians for each of the metrics corresponding to both directions, thus permitting the generation ofmore » {open_quotes}second order{close_quotes} methods. (3) Dikin and Karmarkar geodesic descent methods. For those directions, we make computable the theoretical Luenberger geodesic descent method, since we are able to explicit very accurate expressions of the corresponding geodesics. Convergence results are given.« less

Day to Day Variability and Reliability of Blood Oxidative Stress Markers within a Four-Week Period in Healthy Young Men.

PubMed

Goldfarb, A H; Garten, R S; Waller, J; Labban, J D

2014-01-01

The present study aimed to determine the day to day variability and reliability of several blood oxidative stress markers at rest in a healthy young cohort over a four-week period. Twelve apparently healthy resistance trained males (24.6 ± 3.0 yrs) were tested over 7 visits within 4 weeks with at least 72 hrs between visits at the same time of day. Subjects rested 30 minutes prior to blood being obtained by vacutainer. Results. The highest IntraClass correlations (ICC's) were obtained for protein carbonyls (PC) and oxygen radical absorbance capacity (ORAC) (PC = 0.785 and ORAC = 0.780). Cronbach's α reliability score for PC was 0.967 and for ORAC was 0.961. The ICC's for GSH, GSSG, and the GSSG/TGH ratio ICC were 0.600, 0.573, and 0.570, respectively, with Cronbach's α being 0.913, 0.904, and 0.903, respectively. Xanthine oxidase ICC was 0.163 and Cronbach's α was 0.538. Conclusions. PC and ORAC demonstrated good to excellent reliability while glutathione factors had poor to excellent reliability. Xanthine oxidase showed poor reliability and high variability. These results suggest that the PC and ORAC markers were the most stable and reliable oxidative stress markers in blood and that daily changes across visits should be considered when interpreting resting blood oxidative stress markers.

Stroke Impact Scale 3.0: Reliability and Validity Evaluation of the Korean Version.

PubMed

Choi, Seong Uk; Lee, Hye Sun; Shin, Joon Ho; Ho, Seung Hee; Koo, Mi Jung; Park, Kyoung Hae; Yoon, Jeong Ah; Kim, Dong Min; Oh, Jung Eun; Yu, Se Hwa; Kim, Dong A

2017-06-01

To establish the reliability and validity the Korean version of the Stroke Impact Scale (K-SIS) 3.0. A total of 70 post-stroke patients were enrolled. All subjects were evaluated for general characteristics, Mini-Mental State Examination (MMSE), the National Institutes of Health Stroke Scale (NIHSS), Modified Barthel Index, Hospital Anxiety and Depression Scale (HADS). The SF-36 and K-SIS 3.0 assessed their health-related quality of life. Statistical analysis after evaluation, determined the reliability and validity of the K-SIS 3.0. A total of 70 patients (mean age, 54.97 years) participated in this study. Internal consistency of the SIS 3.0 (Cronbach's alpha) was obtained, and all domains had good co-efficiency, with threshold above 0.70. Test-retest reliability of SIS 3.0 required correlation (Spearman's rho) of the same domain scores obtained on the first and second assessments. Results were above 0.5, with the exception of social participation and mobility. Concurrent validity of K-SIS 3.0 was assessed using the SF-36, and other scales with the same or similar domains. Each domain of K-SIS 3.0 had a positive correlation with corresponding similar domain of SF-36 and other scales (HADS, MMSE, and NIHSS). The newly developed K-SIS 3.0 showed high inter-intra reliability and test-retest reliabilities, together with high concurrent validity with the original and various other scales, for patients with stroke. K-SIS 3.0 can therefore be used for stroke patients, to assess their health-related quality of life and treatment efficacy.

Test-retest reliability and repeatability of renal diffusion tensor MRI in healthy subjects.

PubMed

Cutajar, Marica; Clayden, Jonathan D; Clark, Christopher A; Gordon, Isky

2011-12-01

This study assessed test-retest reliability and repeatability of diffusion tensor imaging (DTI) in the kidneys. Seven healthy volunteers (age range, 19-31 years), were imaged three consecutive times on the same day (short-term reliability) and the same imaging protocol was repeated after a month (long-term reliability). Diffusion-weighted magnetic resonance imaging scans in the coronal-oblique projection of the kidney were acquired on a 1.5 T scanner using a multi-section echo-planar sequence; six contiguous slices each 5 mm thick, diffusion sensitisation along 20 non-collinear directions, TR=730 ms, TE=73 ms and 2 b-values (0 and 400 s mm(-2)). Volunteers were asked to hold their breath throughout each data acquisition (approx. 20 s). The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were obtained from maps generated using dedicated software MIStar (Apollo Medical Imaging, Melbourne, Australia). Statistical analyses of both short- and long-term repeats were carried out from which the within-subject coefficient of variation (wsCV) was calculated. The wsCV obtained for both the ADC and FA values were less than 10% in all the analyses carried out. In addition, paired (repeated measures) t-test was used to measure the variation between the diffusion parameters collected from the two scanning sessions a month apart. It showed no significant difference and the wsCV obtained after comparing the first and second scans were found to be smaller than 15% for both ADC and FA. Renal DTI produces reliable and repeatable results which make longitudinal investigation of patients viable. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Near-Infrared Scintillation of Liquid Argon: Recent Results Obtained with the NIR Facility at Fermilab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Escobar, C. O.; Rubinov, P.; Tilly, E.

After a short review of previous attempts to observe and measure the near-infrared scintillation in liquid argon, we present new results obtained with NIR, a dedicated cryostat at the Fermilab Proton Assembly Building (PAB). The new results give confidence that the near-infrared light can be used as the much needed light signal in large liquid argon time projection chambers.11 pages,

Content validity and reliability of test of gross motor development in Chilean children

PubMed Central

Cano-Cappellacci, Marcelo; Leyton, Fernanda Aleitte; Carreño, Joshua Durán

2016-01-01

ABSTRACT OBJECTIVE To validate a Spanish version of the Test of Gross Motor Development (TGMD-2) for the Chilean population. METHODS Descriptive, transversal, non-experimental validity and reliability study. Four translators, three experts and 92 Chilean children, from five to 10 years, students from a primary school in Santiago, Chile, have participated. The Committee of Experts has carried out translation, back-translation and revision processes to determine the translinguistic equivalence and content validity of the test, using the content validity index in 2013. In addition, a pilot implementation was achieved to determine test reliability in Spanish, by using the intraclass correlation coefficient and Bland-Altman method. We evaluated whether the results presented significant differences by replacing the bat with a racket, using T-test. RESULTS We obtained a content validity index higher than 0.80 for language clarity and relevance of the TGMD-2 for children. There were significant differences in the object control subtest when comparing the results with bat and racket. The intraclass correlation coefficient for reliability inter-rater, intra-rater and test-retest reliability was greater than 0.80 in all cases. CONCLUSIONS The TGMD-2 has appropriate content validity to be applied in the Chilean population. The reliability of this test is within the appropriate parameters and its use could be recommended in this population after the establishment of normative data, setting a further precedent for the validation in other Latin American countries. PMID:26815160

Comparison of orbital volume obtained by tomography and rapid prototyping.

PubMed

Roça, Guilherme Berto; Foggiatto, José Aguiomar; Ono, Maria Cecilia Closs; Ono, Sergio Eiji; da Silva Freitas, Renato

2013-11-01

This study aims to compare orbital volume obtained by helical tomography and rapid prototyping. The study sample was composed of 6 helical tomography scans. Eleven healthy orbits were identified to have their volumes measured. The volumetric analysis with the helical tomography utilized the same protocol developed by the Plastic Surgery Unit of the Federal University of Paraná. From the CT images, 11 prototypes were created, and their respective volumes were analyzed in 2 ways: using software by SolidWorks and by direct analysis, when the prototype was filled with saline solution. For statistical analysis, the results of the volumes of the 11 orbits were considered independent. The average orbital volume measurements obtained by the method of Ono et al was 20.51 cm, the average obtained by the SolidWorks program was 20.64 cm, and the average measured using the prototype method was 21.81 cm. The 3 methods demonstrated a strong correlation between the measurements. The right and left orbits of each patient had similar volumes. The tomographic method for the analysis of orbital volume using the Ono protocol yielded consistent values, and by combining this method with rapid prototyping, both reliability validations of results were enhanced.

Rater reliability and concurrent validity of the Keyboard Personal Computer Style instrument (K-PeCS).

PubMed

Baker, Nancy A; Cook, James R; Redfern, Mark S

2009-01-01

This paper describes the inter-rater and intra-rater reliability, and the concurrent validity of an observational instrument, the Keyboard Personal Computer Style instrument (K-PeCS), which assesses stereotypical postures and movements associated with computer keyboard use. Three trained raters independently rated the video clips of 45 computer keyboard users to ascertain inter-rater reliability, and then re-rated a sub-sample of 15 video clips to ascertain intra-rater reliability. Concurrent validity was assessed by comparing the ratings obtained using the K-PeCS to scores developed from a 3D motion analysis system. The overall K-PeCS had excellent reliability [inter-rater: intra-class correlation coefficients (ICC)=.90; intra-rater: ICC=.92]. Most individual items on the K-PeCS had from good to excellent reliability, although six items fell below ICC=.75. Those K-PeCS items that were assessed for concurrent validity compared favorably to the motion analysis data for all but two items. These results suggest that most items on the K-PeCS can be used to reliably document computer keyboarding style.

Orbiter Autoland reliability analysis

NASA Technical Reports Server (NTRS)

Welch, D. Phillip

1993-01-01

The Space Shuttle Orbiter is the only space reentry vehicle in which the crew is seated upright. This position presents some physiological effects requiring countermeasures to prevent a crewmember from becoming incapacitated. This also introduces a potential need for automated vehicle landing capability. Autoland is a primary procedure that was identified as a requirement for landing following and extended duration orbiter mission. This report documents the results of the reliability analysis performed on the hardware required for an automated landing. A reliability block diagram was used to evaluate system reliability. The analysis considers the manual and automated landing modes currently available on the Orbiter. (Autoland is presently a backup system only.) Results of this study indicate a +/- 36 percent probability of successfully extending a nominal mission to 30 days. Enough variations were evaluated to verify that the reliability could be altered with missions planning and procedures. If the crew is modeled as being fully capable after 30 days, the probability of a successful manual landing is comparable to that of Autoland because much of the hardware is used for both manual and automated landing modes. The analysis indicates that the reliability for the manual mode is limited by the hardware and depends greatly on crew capability. Crew capability for a successful landing after 30 days has not been determined yet.

Inter-Observer, Intra-Observer and Intra-Individual Reliability of Uroflowmetry Tests in Aged Men: A Generalizability Theory Approach.

PubMed

Liu, Ying-Buh; Yang, Stephen S; Hsieh, Cheng-Hsing; Lin, Chia-Da; Chang, Shang-Jen

2014-05-01

To evaluate the inter-observer, intra-observer and intra-individual reliability of uroflowmetry and post-void residual urine (PVR) tests in adult men. Healthy volunteers aged over 40 years were enrolled. Every participant underwent two sets of uroflowmetry and PVR tests with a 2-week interval between the tests. The uroflowmetry tests were interpreted by four urologists independently. Uroflowmetry curves were classified as bell-shaped, bell-shaped with tail, obstructive, restrictive, staccato, interrupted and tower-shaped and scored from 1 (highly abnormal) to 5 (absolutely normal). The agreements between the observers, interpretations and tests within individuals were analyzed using kappa statistics and intraclass correlation coefficients. Generalizability theory with decision analysis was used to determine how many observers, tests, and interpretations were needed to obtain an acceptable reliability (> 0.80). Of 108 volunteers, we randomly selected the uroflowmetry results from 25 participants for the evaluation of reliability. The mean age of the studied adults was 55.3 years. The intra-individual and intra-observer reliability on uroflowmetry tests ranged from good to very good. However, the inter-observer reliability on normalcy and specific type of flow pattern were relatively lower. In generalizability theory, three observers were needed to obtain an acceptable reliability on normalcy of uroflow pattern if the patient underwent uroflowmetry tests twice with one observation. The intra-individual and intra-observer reliability on uroflowmetry tests were good while the inter-observer reliability was relatively lower. To improve inter-observer reliability, the definition of uroflowmetry should be clarified by the International Continence Society. © 2013 Wiley Publishing Asia Pty Ltd.

A Bayesian modification to the Jelinski-Moranda software reliability growth model

NASA Technical Reports Server (NTRS)

Littlewood, B.; Sofer, A.

1983-01-01

The Jelinski-Moranda (JM) model for software reliability was examined. It is suggested that a major reason for the poor results given by this model is the poor performance of the maximum likelihood method (ML) of parameter estimation. A reparameterization and Bayesian analysis, involving a slight modelling change, are proposed. It is shown that this new Bayesian-Jelinski-Moranda model (BJM) is mathematically quite tractable, and several metrics of interest to practitioners are obtained. The BJM and JM models are compared by using several sets of real software failure data collected and in all cases the BJM model gives superior reliability predictions. A change in the assumption which underlay both models to present the debugging process more accurately is discussed.

Reliability measurement for mixed mode failures of 33/11 kilovolt electric power distribution stations.

PubMed

Alwan, Faris M; Baharum, Adam; Hassan, Geehan S

2013-01-01

The reliability of the electrical distribution system is a contemporary research field due to diverse applications of electricity in everyday life and diverse industries. However a few research papers exist in literature. This paper proposes a methodology for assessing the reliability of 33/11 Kilovolt high-power stations based on average time between failures. The objective of this paper is to find the optimal fit for the failure data via time between failures. We determine the parameter estimation for all components of the station. We also estimate the reliability value of each component and the reliability value of the system as a whole. The best fitting distribution for the time between failures is a three parameter Dagum distribution with a scale parameter [Formula: see text] and shape parameters [Formula: see text] and [Formula: see text]. Our analysis reveals that the reliability value decreased by 38.2% in each 30 days. We believe that the current paper is the first to address this issue and its analysis. Thus, the results obtained in this research reflect its originality. We also suggest the practicality of using these results for power systems for both the maintenance of power systems models and preventive maintenance models.

Ultra-short heart rate variability recording reliability: The effect of controlled paced breathing.

PubMed

Melo, Hiago M; Martins, Thiago C; Nascimento, Lucas M; Hoeller, Alexandre A; Walz, Roger; Takase, Emílio

2018-06-04

Recent studies have reported that Heart Rate Variability (HRV) indices remain reliable even during recordings shorter than 5 min, suggesting the ultra-short recording method as a valuable tool for autonomic assessment. However, the minimum time-epoch to obtain a reliable record for all HRV domains (time, frequency, and Poincare geometric measures), as well as the effect of respiratory rate on the reliability of these indices remains unknown. Twenty volunteers had their HRV recorded in a seated position during spontaneous and controlled respiratory rhythms. HRV intervals with 1, 2, and 3 min were correlated with the gold standard period (6-min duration) and the mean values of all indices were compared in the two respiratory rhythm conditions. rMSSD and SD1 were more reliable for recordings with ultra-short duration at all time intervals (r values from 0.764 to 0.950, p < 0.05) for spontaneous breathing condition, whereas the other indices require longer recording time to obtain reliable values. The controlled breathing rhythm evokes stronger r values for time domain indices (r values from 0.83 to 0.99, p < 0.05 for rMSSD), but impairs the mean values replicability of domains across most time intervals. Although the use of standardized breathing increases the correlations coefficients, all HRV indices showed an increase in mean values (t values from 3.79 to 14.94, p < 0.001) except the RR and HF that presented a decrease (t = 4.14 and 5.96, p < 0.0001). Our results indicate that proper ultra-short-term recording method can provide a quick and reliable source of cardiac autonomic nervous system assessment. © 2018 Wiley Periodicals, Inc.

Results of Investigative Tests of Gas Turbine Engine Compressor Blades Obtained by Electrochemical Machining

NASA Astrophysics Data System (ADS)

Kozhina, T. D.; Kurochkin, A. V.

2016-04-01

The paper highlights results of the investigative tests of GTE compressor Ti-alloy blades obtained by the method of electrochemical machining with oscillating tool-electrodes, carried out in order to define the optimal parameters of the ECM process providing attainment of specified blade quality parameters given in the design documentation, while providing maximal performance. The new technological methods suggested based on the results of the tests; in particular application of vibrating tool-electrodes and employment of locating elements made of high-strength materials, significantly extend the capabilities of this method.

An experiment in software reliability

NASA Technical Reports Server (NTRS)

Dunham, J. R.; Pierce, J. L.

1986-01-01

The results of a software reliability experiment conducted in a controlled laboratory setting are reported. The experiment was undertaken to gather data on software failures and is one in a series of experiments being pursued by the Fault Tolerant Systems Branch of NASA Langley Research Center to find a means of credibly performing reliability evaluations of flight control software. The experiment tests a small sample of implementations of radar tracking software having ultra-reliability requirements and uses n-version programming for error detection, and repetitive run modeling for failure and fault rate estimation. The experiment results agree with those of Nagel and Skrivan in that the program error rates suggest an approximate log-linear pattern and the individual faults occurred with significantly different error rates. Additional analysis of the experimental data raises new questions concerning the phenomenon of interacting faults. This phenomenon may provide one explanation for software reliability decay.

On the Simulation-Based Reliability of Complex Emergency Logistics Networks in Post-Accident Rescues.

PubMed

Wang, Wei; Huang, Li; Liang, Xuedong

2018-01-06

This paper investigates the reliability of complex emergency logistics networks, as reliability is crucial to reducing environmental and public health losses in post-accident emergency rescues. Such networks' statistical characteristics are analyzed first. After the connected reliability and evaluation indices for complex emergency logistics networks are effectively defined, simulation analyses of network reliability are conducted under two different attack modes using a particular emergency logistics network as an example. The simulation analyses obtain the varying trends in emergency supply times and the ratio of effective nodes and validates the effects of network characteristics and different types of attacks on network reliability. The results demonstrate that this emergency logistics network is both a small-world and a scale-free network. When facing random attacks, the emergency logistics network steadily changes, whereas it is very fragile when facing selective attacks. Therefore, special attention should be paid to the protection of supply nodes and nodes with high connectivity. The simulation method provides a new tool for studying emergency logistics networks and a reference for similar studies.

On the Simulation-Based Reliability of Complex Emergency Logistics Networks in Post-Accident Rescues

PubMed Central

Wang, Wei; Huang, Li; Liang, Xuedong

2018-01-01

This paper investigates the reliability of complex emergency logistics networks, as reliability is crucial to reducing environmental and public health losses in post-accident emergency rescues. Such networks’ statistical characteristics are analyzed first. After the connected reliability and evaluation indices for complex emergency logistics networks are effectively defined, simulation analyses of network reliability are conducted under two different attack modes using a particular emergency logistics network as an example. The simulation analyses obtain the varying trends in emergency supply times and the ratio of effective nodes and validates the effects of network characteristics and different types of attacks on network reliability. The results demonstrate that this emergency logistics network is both a small-world and a scale-free network. When facing random attacks, the emergency logistics network steadily changes, whereas it is very fragile when facing selective attacks. Therefore, special attention should be paid to the protection of supply nodes and nodes with high connectivity. The simulation method provides a new tool for studying emergency logistics networks and a reference for similar studies. PMID:29316614

Modeling service time reliability in urban ferry system

NASA Astrophysics Data System (ADS)

Chen, Yifan; Luo, Sida; Zhang, Mengke; Shen, Hanxia; Xin, Feifei; Luo, Yujie

2017-09-01

The urban ferry system can carry a large number of travelers, which may alleviate the pressure on road traffic. As an indicator of its service quality, service time reliability (STR) plays an essential part in attracting travelers to the ferry system. A wide array of studies have been conducted to analyze the STR of land transportation. However, the STR of ferry systems has received little attention in the transportation literature. In this study, a model was established to obtain the STR in urban ferry systems. First, the probability density function (PDF) of the service time provided by ferry systems was constructed. Considering the deficiency of the queuing theory, this PDF was determined by Bayes’ theorem. Then, to validate the function, the results of the proposed model were compared with those of the Monte Carlo simulation. With the PDF, the reliability could be determined mathematically by integration. Results showed how the factors including the frequency, capacity, time schedule and ferry waiting time affected the STR under different degrees of congestion in ferry systems. Based on these results, some strategies for improving the STR were proposed. These findings are of great significance to increasing the share of ferries among various urban transport modes.

Legionella in water samples: how can you interpret the results obtained by quantitative PCR?

PubMed

Ditommaso, Savina; Ricciardi, Elisa; Giacomuzzi, Monica; Arauco Rivera, Susan R; Zotti, Carla M

2015-02-01

Evaluation of the potential risk associated with Legionella has traditionally been determined from culture-based methods. Quantitative polymerase chain reaction (qPCR) is an alternative tool that offers rapid, sensitive and specific detection of Legionella in environmental water samples. In this study we compare the results obtained by conventional qPCR (iQ-Check™ Quanti Legionella spp.; Bio-Rad) and by culture method on artificial samples prepared in Page's saline by addiction of Legionella pneumophila serogroup 1 (ATCC 33152) and we analyse the selective quantification of viable Legionella cells by the qPCR-PMA method. The amount of Legionella DNA (GU) determined by qPCR was 28-fold higher than the load detected by culture (CFU). Applying the qPCR combined with PMA treatment we obtained a reduction of 98.5% of the qPCR signal from dead cells. We observed a dissimilarity in the ability of PMA to suppress the PCR signal in samples with different amounts of bacteria: the effective elimination of detection signals by PMA depended on the concentration of GU and increasing amounts of cells resulted in higher values of reduction. Using the results from this study we created an algorithm to facilitate the interpretation of viable cell level estimation with qPCR-PMA. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reliability Generalization (RG) Analysis: The Test Is Not Reliable

ERIC Educational Resources Information Center

Warne, Russell

2008-01-01

Literature shows that most researchers are unaware of some of the characteristics of reliability. This paper clarifies some misconceptions by describing the procedures, benefits, and limitations of reliability generalization while using it to illustrate the nature of score reliability. Reliability generalization (RG) is a meta-analytic method…

Reliability Analysis of the MSC System

NASA Astrophysics Data System (ADS)

Kim, Young-Soo; Lee, Do-Kyoung; Lee, Chang-Ho; Woo, Sun-Hee

2003-09-01

MSC (Multi-Spectral Camera) is the payload of KOMPSAT-2, which is being developed for earth imaging in optical and near-infrared region. The design of the MSC is completed and its reliability has been assessed from part level to the MSC system level. The reliability was analyzed in worst case and the analysis results showed that the value complies the required value of 0.9. In this paper, a calculation method of reliability for the MSC system is described, and assessment result is presented and discussed.

Component Reliability Testing of Long-Life Sorption Cryocoolers

NASA Technical Reports Server (NTRS)

Bard, S.; Wu, J.; Karlmann, P.; Mirate, C.; Wade, L.

1994-01-01

This paper summarizes ongoing experiments characterizing the ability of critical sorption cryocooler components to achieve highly reliable operation for long-life space missions. Test data obtained over the past several years at JPL are entirely consistent with achieving ten year life for sorption compressors, electrical heaters, container materials, valves, and various sorbent materials suitable for driving 8 to 180 K refrigeration stages. Test results for various compressor systems are reported. Planned future tests necessary to gain a detailed understanding of the sensitivity of cooler performance and component life to operating constraints, design configurations, and fabrication, assembly and handling techniques, are also discussed.

Measuring acuity of the approximate number system reliably and validly: the evaluation of an adaptive test procedure

PubMed Central

Lindskog, Marcus; Winman, Anders; Juslin, Peter; Poom, Leo

2013-01-01

Two studies investigated the reliability and predictive validity of commonly used measures and models of Approximate Number System acuity (ANS). Study 1 investigated reliability by both an empirical approach and a simulation of maximum obtainable reliability under ideal conditions. Results showed that common measures of the Weber fraction (w) are reliable only when using a substantial number of trials, even under ideal conditions. Study 2 compared different purported measures of ANS acuity as for convergent and predictive validity in a within-subjects design and evaluated an adaptive test using the ZEST algorithm. Results showed that the adaptive measure can reduce the number of trials needed to reach acceptable reliability. Only direct tests with non-symbolic numerosity discriminations of stimuli presented simultaneously were related to arithmetic fluency. This correlation remained when controlling for general cognitive ability and perceptual speed. Further, the purported indirect measure of ANS acuity in terms of the Numeric Distance Effect (NDE) was not reliable and showed no sign of predictive validity. The non-symbolic NDE for reaction time was significantly related to direct w estimates in a direction contrary to the expected. Easier stimuli were found to be more reliable, but only harder (7:8 ratio) stimuli contributed to predictive validity. PMID:23964256

Accuracy and reliability of observational gait analysis data: judgments of push-off in gait after stroke.

PubMed

McGinley, Jennifer L; Goldie, Patricia A; Greenwood, Kenneth M; Olney, Sandra J

2003-02-01

Physical therapists routinely observe gait in clinical practice. The purpose of this study was to determine the accuracy and reliability of observational assessments of push-off in gait after stroke. Eighteen physical therapists and 11 subjects with hemiplegia following a stroke participated in the study. Measurements of ankle power generation were obtained from subjects following stroke using a gait analysis system. Concurrent videotaped gait performances were observed by the physical therapists on 2 occasions. Ankle power generation at push-off was scored as either normal or abnormal using two 11-point rating scales. These observational ratings were correlated with the measurements of peak ankle power generation. A high correlation was obtained between the observational ratings and the measurements of ankle power generation (mean Pearson r=.84). Interobserver reliability was moderately high (mean intraclass correlation coefficient [ICC (2,1)]=.76). Intraobserver reliability also was high, with a mean ICC (2,1) of.89 obtained. Physical therapists were able to make accurate and reliable judgments of push-off in videotaped gait of subjects following stroke using observational assessment. Further research is indicated to explore the accuracy and reliability of data obtained with observational gait analysis as it occurs in clinical practice.

The weakest t-norm based intuitionistic fuzzy fault-tree analysis to evaluate system reliability.

PubMed

Kumar, Mohit; Yadav, Shiv Prasad

2012-07-01

In this paper, a new approach of intuitionistic fuzzy fault-tree analysis is proposed to evaluate system reliability and to find the most critical system component that affects the system reliability. Here weakest t-norm based intuitionistic fuzzy fault tree analysis is presented to calculate fault interval of system components from integrating expert's knowledge and experience in terms of providing the possibility of failure of bottom events. It applies fault-tree analysis, α-cut of intuitionistic fuzzy set and T(ω) (the weakest t-norm) based arithmetic operations on triangular intuitionistic fuzzy sets to obtain fault interval and reliability interval of the system. This paper also modifies Tanaka et al.'s fuzzy fault-tree definition. In numerical verification, a malfunction of weapon system "automatic gun" is presented as a numerical example. The result of the proposed method is compared with the listing approaches of reliability analysis methods. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Development of a Conservative Model Validation Approach for Reliable Analysis

DTIC Science & Technology

2015-01-01

CIE 2015 August 2-5, 2015, Boston, Massachusetts, USA [DRAFT] DETC2015-46982 DEVELOPMENT OF A CONSERVATIVE MODEL VALIDATION APPROACH FOR RELIABLE...obtain a conservative simulation model for reliable design even with limited experimental data. Very little research has taken into account the...3, the proposed conservative model validation is briefly compared to the conventional model validation approach. Section 4 describes how to account

Availability and End-to-end Reliability in Low Duty Cycle Multihop Wireless Sensor Networks.

PubMed

Suhonen, Jukka; Hämäläinen, Timo D; Hännikäinen, Marko

2009-01-01

A wireless sensor network (WSN) is an ad-hoc technology that may even consist of thousands of nodes, which necessitates autonomic, self-organizing and multihop operations. A typical WSN node is battery powered, which makes the network lifetime the primary concern. The highest energy efficiency is achieved with low duty cycle operation, however, this alone is not enough. WSNs are deployed for different uses, each requiring acceptable Quality of Service (QoS). Due to the unique characteristics of WSNs, such as dynamic wireless multihop routing and resource constraints, the legacy QoS metrics are not feasible as such. We give a new definition to measure and implement QoS in low duty cycle WSNs, namely availability and reliability. Then, we analyze the effect of duty cycling for reaching the availability and reliability. The results are obtained by simulations with ZigBee and proprietary TUTWSN protocols. Based on the results, we also propose a data forwarding algorithm suitable for resource constrained WSNs that guarantees end-to-end reliability while adding a small overhead that is relative to the packet error rate (PER). The forwarding algorithm guarantees reliability up to 30% PER.

An assessment of consistence of exhaust gas emission test results obtained under controlled NEDC conditions

NASA Astrophysics Data System (ADS)

Balawender, K.; Jaworski, A.; Kuszewski, H.; Lejda, K.; Ustrzycki, A.

2016-09-01

Measurements concerning emissions of pollutants contained in automobile combustion engine exhaust gases is of primary importance in view of their harmful impact on the natural environment. This paper presents results of tests aimed at determining exhaust gas pollutant emissions from a passenger car engine obtained under repeatable conditions on a chassis dynamometer. The test set-up was installed in a controlled climate chamber allowing to maintain the temperature conditions within the range from -20°C to +30°C. The analysis covered emissions of such components as CO, CO2, NOx, CH4, THC, and NMHC. The purpose of the study was to assess repeatability of results obtained in a number of tests performed as per NEDC test plan. The study is an introductory stage of a wider research project concerning the effect of climate conditions and fuel type on emission of pollutants contained in exhaust gases generated by automotive vehicles.

A Comparative Evaluation of Mixed Dentition Analysis on Reliability of Cone Beam Computed Tomography Image Compared to Plaster Model

PubMed Central

Gowd, Snigdha; Shankar, T; Dash, Samarendra; Sahoo, Nivedita; Chatterjee, Suravi; Mohanty, Pritam

2017-01-01

Aims and Objective: The aim of the study was to evaluate the reliability of cone beam computed tomography (CBCT) obtained image over plaster model for the assessment of mixed dentition analysis. Materials and Methods: Thirty CBCT-derived images and thirty plaster models were derived from the dental archives, and Moyer's and Tanaka-Johnston analyses were performed. The data obtained were interpreted and analyzed statistically using SPSS 10.0/PC (SPSS Inc., Chicago, IL, USA). Descriptive and analytical analysis along with Student's t-test was performed to qualitatively evaluate the data and P < 0.05 was considered statistically significant. Results: Statistically, significant results were obtained on data comparison between CBCT-derived images and plaster model; the mean for Moyer's analysis in the left and right lower arch for CBCT and plaster model was 21.2 mm, 21.1 mm and 22.5 mm, 22.5 mm, respectively. Conclusion: CBCT-derived images were less reliable as compared to data obtained directly from plaster model for mixed dentition analysis. PMID:28852639

Characterization of perovskite solar cells: Towards a reliable measurement protocol

NASA Astrophysics Data System (ADS)

Zimmermann, Eugen; Wong, Ka Kan; Müller, Michael; Hu, Hao; Ehrenreich, Philipp; Kohlstädt, Markus; Würfel, Uli; Mastroianni, Simone; Mathiazhagan, Gayathri; Hinsch, Andreas; Gujar, Tanaji P.; Thelakkat, Mukundan; Pfadler, Thomas; Schmidt-Mende, Lukas

2016-09-01

Lead halide perovskite solar cells have shown a tremendous rise in power conversion efficiency with reported record efficiencies of over 20% making this material very promising as a low cost alternative to conventional inorganic solar cells. However, due to a differently severe "hysteretic" behaviour during current density-voltage measurements, which strongly depends on scan rate, device and measurement history, preparation method, device architecture, etc., commonly used solar cell measurements do not give reliable or even reproducible results. For the aspect of commercialization and the possibility to compare results of different devices among different laboratories, it is necessary to establish a measurement protocol which gives reproducible results. Therefore, we compare device characteristics derived from standard current density-voltage measurements with stabilized values obtained from an adaptive tracking of the maximum power point and the open circuit voltage as well as characteristics extracted from time resolved current density-voltage measurements. Our results provide insight into the challenges of a correct determination of device performance and propose a measurement protocol for a reliable characterisation which is easy to implement and has been tested on varying perovskite solar cells fabricated in different laboratories.

The extent of food waste generation across EU-27: different calculation methods and the reliability of their results.

PubMed

Bräutigam, Klaus-Rainer; Jörissen, Juliane; Priefer, Carmen

2014-08-01

The reduction of food waste is seen as an important societal issue with considerable ethical, ecological and economic implications. The European Commission aims at cutting down food waste to one-half by 2020. However, implementing effective prevention measures requires knowledge of the reasons and the scale of food waste generation along the food supply chain. The available data basis for Europe is very heterogeneous and doubts about its reliability are legitimate. This mini-review gives an overview of available data on food waste generation in EU-27 and discusses their reliability against the results of own model calculations. These calculations are based on a methodology developed on behalf of the Food and Agriculture Organization of the United Nations and provide data on food waste generation for each of the EU-27 member states, broken down to the individual stages of the food chain and differentiated by product groups. The analysis shows that the results differ significantly, depending on the data sources chosen and the assumptions made. Further research is much needed in order to improve the data stock, which builds the basis for the monitoring and management of food waste. © The Author(s) 2014.

Reliability of SNOMED-CT Coding by Three Physicians using Two Terminology Browsers

PubMed Central

Chiang, Michael F.; Hwang, John C.; Yu, Alexander C.; Casper, Daniel S.; Cimino, James J.; Starren, Justin

2006-01-01

SNOMED-CT has been promoted as a reference terminology for electronic health record (EHR) systems. Many important EHR functions are based on the assumption that medical concepts will be coded consistently by different users. This study is designed to measure agreement among three physicians using two SNOMED-CT terminology browsers to encode 242 concepts from five ophthalmology case presentations in a publicly-available clinical journal. Inter-coder reliability, based on exact coding match by each physician, was 44% using one browser and 53% using the other. Intra-coder reliability testing revealed that a different SNOMED-CT code was obtained up to 55% of the time when the two browsers were used by one user to encode the same concept. These results suggest that the reliability of SNOMED-CT coding is imperfect, and may be a function of browsing methodology. A combination of physician training, terminology refinement, and browser improvement may help increase the reproducibility of SNOMED-CT coding. PMID:17238317

Obtaining orthotropic elasticity tensor using entries zeroing method.

NASA Astrophysics Data System (ADS)

Gierlach, Bartosz; Danek, Tomasz

2017-04-01

rotation. Computations were parallelized with OpenMP to decrease computational time what enables different tensors to be processed by different threads. As a result the distributions of rotated tensor entries values were obtained. For the entries which were to be zeroed we can observe almost normal distributions having mean equal to zero or sum of two normal distributions having inverse means. Non-zero entries represent different distributions with two or three maxima. Analysis of obtained results shows that described method produces consistent values of quaternions used to rotate tensors. Despite of less complex target function in a process of optimization in comparison to common approach, entries zeroing method provides results which can be applied to obtain an orthotropic tensor with good reliability. Modification of the method can produce also a tool for obtaining effective tensors belonging to another symmetry classes. This research was supported by the Polish National Science Center under contract No. DEC-2013/11/B/ST10/0472.

Glucose Meters: A Review of Technical Challenges to Obtaining Accurate Results

PubMed Central

Tonyushkina, Ksenia; Nichols, James H.

2009-01-01

, anemia, hypotension, and other disease states. This article reviews the challenges involved in obtaining accurate glucose meter results. PMID:20144348

Operation Reliability Assessment for Cutting Tools by Applying a Proportional Covariate Model to Condition Monitoring Information

PubMed Central

Cai, Gaigai; Chen, Xuefeng; Li, Bing; Chen, Baojia; He, Zhengjia

2012-01-01

The reliability of cutting tools is critical to machining precision and production efficiency. The conventional statistic-based reliability assessment method aims at providing a general and overall estimation of reliability for a large population of identical units under given and fixed conditions. However, it has limited effectiveness in depicting the operational characteristics of a cutting tool. To overcome this limitation, this paper proposes an approach to assess the operation reliability of cutting tools. A proportional covariate model is introduced to construct the relationship between operation reliability and condition monitoring information. The wavelet packet transform and an improved distance evaluation technique are used to extract sensitive features from vibration signals, and a covariate function is constructed based on the proportional covariate model. Ultimately, the failure rate function of the cutting tool being assessed is calculated using the baseline covariate function obtained from a small sample of historical data. Experimental results and a comparative study show that the proposed method is effective for assessing the operation reliability of cutting tools. PMID:23201980

Electrochemical Cell for Obtaining Oxygen from Carbon Dioxide Atmospheres

NASA Technical Reports Server (NTRS)

Hooker, Matthew; Rast, H. Edward; Rogers, Darren K.; Borja, Luis; Clark, Kevin; Fleming, Kimberly; Mcgurren, Michael; Oldaker, Tom; Sweet, Nanette

1989-01-01

To support human life on the Martian surface, an electrochemical device will be required to obtain oxygen from the carbon dioxide rich atmosphere. The electrolyte employed in such a device must be constructed from extremely thin, dense membranes to efficiently acquire the oxygen necessary to support life. A forming process used industrially in the production of multilayer capacitors and electronic substrates was adapted to form the thin membranes required. The process, known as the tape casting, involves the suspension consisting of solvents and binders. The suspension is passed under a blade, resulting in the production of ceramic membranes between 0.1 and 0.5 mm thick. Once fired, the stabilized zirconia membranes were assembled into the cell design by employing a zirconium phosphate solution as the sealing agent. The resulting ceramic-to-ceramic seals were found to be structurally sound and gas-tight. Furthermore, by using a zirconia-based solution to assemble the cell, the problem of a thermal expansion mismatch was alleviated. By adopting an industrial forming process to produce thin membranes, an electrochemical cell for obtaining oxygen from carbon dioxide was produced. The proposed cell design is unique in that it does not require a complicated manifold system for separating the various gases present in this process, nor does it require a series of complex electrical connections. Thus, the device can reliably obtain the vital oxygen supply from the toxic carbon dioxide atmosphere.

Reliability model generator

NASA Technical Reports Server (NTRS)

Cohen, Gerald C. (Inventor); McMann, Catherine M. (Inventor)

1991-01-01

An improved method and system for automatically generating reliability models for use with a reliability evaluation tool is described. The reliability model generator of the present invention includes means for storing a plurality of low level reliability models which represent the reliability characteristics for low level system components. In addition, the present invention includes means for defining the interconnection of the low level reliability models via a system architecture description. In accordance with the principles of the present invention, a reliability model for the entire system is automatically generated by aggregating the low level reliability models based on the system architecture description.

A reliability analysis tool for SpaceWire network

NASA Astrophysics Data System (ADS)

Zhou, Qiang; Zhu, Longjiang; Fei, Haidong; Wang, Xingyou

2017-04-01

A SpaceWire is a standard for on-board satellite networks as the basis for future data-handling architectures. It is becoming more and more popular in space applications due to its technical advantages, including reliability, low power and fault protection, etc. High reliability is the vital issue for spacecraft. Therefore, it is very important to analyze and improve the reliability performance of the SpaceWire network. This paper deals with the problem of reliability modeling and analysis with SpaceWire network. According to the function division of distributed network, a reliability analysis method based on a task is proposed, the reliability analysis of every task can lead to the system reliability matrix, the reliability result of the network system can be deduced by integrating these entire reliability indexes in the matrix. With the method, we develop a reliability analysis tool for SpaceWire Network based on VC, where the computation schemes for reliability matrix and the multi-path-task reliability are also implemented. By using this tool, we analyze several cases on typical architectures. And the analytic results indicate that redundancy architecture has better reliability performance than basic one. In practical, the dual redundancy scheme has been adopted for some key unit, to improve the reliability index of the system or task. Finally, this reliability analysis tool will has a directive influence on both task division and topology selection in the phase of SpaceWire network system design.

Establishing Reliable Cognitive Change in Children with Epilepsy: The Procedures and Results for a Sample with Epilepsy

ERIC Educational Resources Information Center

van Iterson, Loretta; Augustijn, Paul B.; de Jong, Peter F.; van der Leij, Aryan

2013-01-01

The goal of this study was to investigate reliable cognitive change in epilepsy by developing computational procedures to determine reliable change index scores (RCIs) for the Dutch Wechsler Intelligence Scales for Children. First, RCIs were calculated based on stability coefficients from a reference sample. Then, these RCIs were applied to a…

Timeline historical review of income and financial transactions: a reliable assessment of personal finances.

PubMed

Black, Anne C; Serowik, Kristin L; Ablondi, Karen M; Rosen, Marc I

2013-01-01

The need for accurate and reliable information about income and resources available to individuals with psychiatric disabilities is critical for the assessment of need and evaluation of programs designed to alleviate financial hardship or affect finance allocation. Measurement of finances is ubiquitous in studies of economics, poverty, and social services. However, evidence has demonstrated that these measures often contain error. We compare the 1-week test-retest reliability of income and finance data from 24 adult psychiatric outpatients using assessment-as-usual (AAU) and a new instrument, the Timeline Historical Review of Income and Financial Transactions (THRIFT). Reliability estimates obtained with the THRIFT for Income (0.77), Expenses (0.91), and Debt (0.99) domains were significantly better than those obtained with AAU. Reliability estimates for Balance did not differ. THRIFT reduced measurement error and provided more reliable information than AAU for assessment of personal finances in psychiatric patients receiving Social Security benefits. The instrument also may be useful with other low-income groups.

Differences in Reliability of Reproductive History Recall among Women in North Africa

ERIC Educational Resources Information Center

Soliman, Amr; Allen, Katharine; Lo, An-Chi; Banerjee, Mousumi; Hablas, Ahmed; Benider, Abdellatif; Benchekroun, Nadya; Samir, Salwa; Omar, Hoda G.; Merajver, Sofia; Mullan, Patricia

2009-01-01

Breast cancer is the most common cancer among women in North Africa. Women in this region have unique reproductive profiles. It is essential to obtain reliable information on reproductive histories to help better understand the relationship between reductive health and breast cancer. We tested the reliability of a reproductive history-based…

CARES/Life Software for Designing More Reliable Ceramic Parts

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Powers, Lynn M.; Baker, Eric H.

1997-01-01

Products made from advanced ceramics show great promise for revolutionizing aerospace and terrestrial propulsion, and power generation. However, ceramic components are difficult to design because brittle materials in general have widely varying strength values. The CAPES/Life software eases this task by providing a tool to optimize the design and manufacture of brittle material components using probabilistic reliability analysis techniques. Probabilistic component design involves predicting the probability of failure for a thermomechanically loaded component from specimen rupture data. Typically, these experiments are performed using many simple geometry flexural or tensile test specimens. A static, dynamic, or cyclic load is applied to each specimen until fracture. Statistical strength and SCG (fatigue) parameters are then determined from these data. Using these parameters and the results obtained from a finite element analysis, the time-dependent reliability for a complex component geometry and loading is then predicted. Appropriate design changes are made until an acceptable probability of failure has been reached.

System-reliability studies for wave-energy generation

NASA Astrophysics Data System (ADS)

Dawson, J. M.; Din, S.; Mytton, M. G.; Shore, N. L.; Stansfield, H. B.

1980-06-01

A study is reported that is being undertaken in the United Kingdom to determine means of developing the potential of the large wave-energy resource around the coast, in particular, that to the west facing the Atlantic. It is shown that derivation of the mean annual energy to be expected involved knowledge, not only of the wave climates, conversion efficiency characteristics of the proposed devices and of the power transmission system, but also of factors reflecting the availability overall. Attention is given to a simplified approach to the quantifying of reliability for each stage of the process. An appropriate method of analysis is established and a summary of the results obtained is given.

Compound estimation procedures in reliability

NASA Technical Reports Server (NTRS)

Barnes, Ron

1990-01-01

At NASA, components and subsystems of components in the Space Shuttle and Space Station generally go through a number of redesign stages. While data on failures for various design stages are sometimes available, the classical procedures for evaluating reliability only utilize the failure data on the present design stage of the component or subsystem. Often, few or no failures have been recorded on the present design stage. Previously, Bayesian estimators for the reliability of a single component, conditioned on the failure data for the present design, were developed. These new estimators permit NASA to evaluate the reliability, even when few or no failures have been recorded. Point estimates for the latter evaluation were not possible with the classical procedures. Since different design stages of a component (or subsystem) generally have a good deal in common, the development of new statistical procedures for evaluating the reliability, which consider the entire failure record for all design stages, has great intuitive appeal. A typical subsystem consists of a number of different components and each component has evolved through a number of redesign stages. The present investigations considered compound estimation procedures and related models. Such models permit the statistical consideration of all design stages of each component and thus incorporate all the available failure data to obtain estimates for the reliability of the present version of the component (or subsystem). A number of models were considered to estimate the reliability of a component conditioned on its total failure history from two design stages. It was determined that reliability estimators for the present design stage, conditioned on the complete failure history for two design stages have lower risk than the corresponding estimators conditioned only on the most recent design failure data. Several models were explored and preliminary models involving bivariate Poisson distribution and the

Reliability of recordings of subgingival calculus detected using an ultrasonic device.

PubMed

Corraini, Priscila; López, Rodrigo

2015-04-01

To assess the intra-examiner reliability of recordings of subgingival calculus detected using an ultrasonic device, and to investigate the influence of subject-, tooth- and site-level factors on the reliability of these subgingival calculus recordings. On two occasions, within a 1-week interval, 147 adult periodontitis patients received a full-mouth clinical periodontal examination by a single trained examiner. Duplicate subgingival calculus recordings, in six sites per tooth, were obtained using an ultrasonic device for calculus detection and removal. Agreement was observed in 65 % of the 22,584 duplicate subgingival calculus recordings, ranging 45 % to 83 % according to subject. Using hierarchical modeling, disagreements in the subgingival calculus duplicate recordings were more likely in all other sites than the mid-buccal, and in sites harboring supragingival calculus. Disagreements were less likely in sites with PD ≥  4 mm and with furcation involvement  ≥  degree 2. Bleeding on probing or suppuration did not influence the reliability of subgingival calculus. At the subject-level, disagreements were less likely in patients presenting with the highest and lowest extent categories of the covariate subgingival calculus. The reliability of subgingival calculus recordings using the ultrasound technology is reasonable. The results of the present study suggest that the reliability of subgingival calculus recordings is not influenced by the presence of inflammation. Moreover, subgingival calculus can be more reliably detected using the ultrasound device at sites with higher need for periodontal therapy, i.e., sites presenting with deep pockets and premolars and molars with furcation involvement.

Reliability of rehabilitative ultrasonographic imaging for muscle thickness measurement of the rhomboid major.

PubMed

Jeong, Ju Ri; Ko, Young Jun; Ha, Hyun Geun; Lee, Wan Hee

2016-03-01

This study was to establish inter-rater and intrarater reliability of the rehabilitative ultrasonographic imaging (RUSI) technique for muscle thickness measurement of the rhomboid major at rest and with the shoulder abducted to 90°. Twenty-four young adults (eight men, 16 women; right-handed; mean age [±SD], 24·4 years [±2·6]) with no history of neck, shoulder, or arm pain were recruited. Rhomboid major muscle images were obtained in the resting position and with shoulder in 90° abduction using an ultrasonography system with a 7·5-MHz linear transducer. In these two positions, the examiners found the site at which the transducer could be placed. Two examiners obtained the images of all participants in three test sessions at random. Intraclass correlation coefficients (ICC) were used to estimate reliability. All ICCs (95% CI) were >0·75, ranging from 0·93 to 0·98, which indicates good reliability. The ICCs for inter-rater reliability ranged from 0·75 to 0·94. For the absolute value of the difference in the intra-examiner reliability between the right and left ratios, the ICCs ranged from 0·58 to 0·91. In this study, the intra- and interexaminer reliability of muscle thickness measurements of the rhomboid major were good. Therefore, we suggest that muscle thickness measurements of the rhomboid major obtained with the RUSI technique would be useful for clinical rehabilitative assessment. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Suicide reporting content analysis: abstract development and reliability.

PubMed

Gould, Madelyn S; Midle, Jennifer Bassett; Insel, Beverly; Kleinman, Marjorie

2007-01-01

Despite substantial research on media influences and the development of media guidelines on suicide reporting, research on the specifics of media stories that facilitate suicide contagion has been limited. The goal of the present study was to develop a content analytic strategy to code features in media suicide reports presumed to be influential in suicide contagion and determine the interrater reliability of the qualitative characteristics abstracted from newspaper stories. A random subset of 151 articles from a database of 1851 newspaper suicide stories published during 1988 through 1996, which were collected as part of a national study in the United States to identify factors associated with the initiation of youth suicide clusters, were evaluated. Using a well-defined content-analysis procedure, the agreement between raters in scoring key concepts of suicide reports from the headline, the pictorial presentation, and the text were evaluated. The results show that while the majority of variables in the content analysis were very reliable, assessed using the kappa statistic, and obtained excellent percentages of agreement, the reliability of complicated constructs, such as sensationalizing, glorifying, or romanticizing the suicide, was comparatively low. The data emphasize that before effective guidelines and responsible suicide reporting can ensue, further explication of suicide story constructs is necessary to ensure the implementation and compliance of responsible reporting on behalf of the media.

Reliability Estimation of Parameters of Helical Wind Turbine with Vertical Axis

PubMed Central

Dumitrascu, Adela-Eliza; Lepadatescu, Badea; Dumitrascu, Dorin-Ion; Nedelcu, Anisor; Ciobanu, Doina Valentina

2015-01-01

Due to the prolonged use of wind turbines they must be characterized by high reliability. This can be achieved through a rigorous design, appropriate simulation and testing, and proper construction. The reliability prediction and analysis of these systems will lead to identifying the critical components, increasing the operating time, minimizing failure rate, and minimizing maintenance costs. To estimate the produced energy by the wind turbine, an evaluation approach based on the Monte Carlo simulation model is developed which enables us to estimate the probability of minimum and maximum parameters. In our simulation process we used triangular distributions. The analysis of simulation results has been focused on the interpretation of the relative frequency histograms and cumulative distribution curve (ogive diagram), which indicates the probability of obtaining the daily or annual energy output depending on wind speed. The experimental researches consist in estimation of the reliability and unreliability functions and hazard rate of the helical vertical axis wind turbine designed and patented to climatic conditions for Romanian regions. Also, the variation of power produced for different wind speeds, the Weibull distribution of wind probability, and the power generated were determined. The analysis of experimental results indicates that this type of wind turbine is efficient at low wind speed. PMID:26167524

Reliability Estimation of Parameters of Helical Wind Turbine with Vertical Axis.

PubMed

Dumitrascu, Adela-Eliza; Lepadatescu, Badea; Dumitrascu, Dorin-Ion; Nedelcu, Anisor; Ciobanu, Doina Valentina

2015-01-01

Due to the prolonged use of wind turbines they must be characterized by high reliability. This can be achieved through a rigorous design, appropriate simulation and testing, and proper construction. The reliability prediction and analysis of these systems will lead to identifying the critical components, increasing the operating time, minimizing failure rate, and minimizing maintenance costs. To estimate the produced energy by the wind turbine, an evaluation approach based on the Monte Carlo simulation model is developed which enables us to estimate the probability of minimum and maximum parameters. In our simulation process we used triangular distributions. The analysis of simulation results has been focused on the interpretation of the relative frequency histograms and cumulative distribution curve (ogive diagram), which indicates the probability of obtaining the daily or annual energy output depending on wind speed. The experimental researches consist in estimation of the reliability and unreliability functions and hazard rate of the helical vertical axis wind turbine designed and patented to climatic conditions for Romanian regions. Also, the variation of power produced for different wind speeds, the Weibull distribution of wind probability, and the power generated were determined. The analysis of experimental results indicates that this type of wind turbine is efficient at low wind speed.

The Reliability and Legality of Online Education

ERIC Educational Resources Information Center

Agbebaku, C. A.; Adavbiele, A. Justina

2016-01-01

Today, the classroom beyond the border through online Open University education in Nigeria has made it possible for many students to obtain university degrees. However, the reliability and legality of such degrees have become questionable. This paper is a descriptive exploratory case study regarding the public and private sector end-users, whose…

Preliminary Results Obtained in Integrated Safety Analysis of NASA Aviation Safety Program Technologies

NASA Technical Reports Server (NTRS)

2001-01-01

This is a listing of recent unclassified RTO technical publications processed by the NASA Center for AeroSpace Information from January 1, 2001 through March 31, 2001 available on the NASA Aeronautics and Space Database. Contents include 1) Cognitive Task Analysis; 2) RTO Educational Notes; 3) The Capability of Virtual Reality to Meet Military Requirements; 4) Aging Engines, Avionics, Subsystems and Helicopters; 5) RTO Meeting Proceedings; 6) RTO Technical Reports; 7) Low Grazing Angle Clutter...; 8) Verification and Validation Data for Computational Unsteady Aerodynamics; 9) Space Observation Technology; 10) The Human Factor in System Reliability...; 11) Flight Control Design...; 12) Commercial Off-the-Shelf Products in Defense Applications.

Does a web-based feedback training program result in improved reliability in clinicians' ratings of the Global Assessment of Functioning (GAF) Scale?

PubMed

Støre-Valen, Jakob; Ryum, Truls; Pedersen, Geir A F; Pripp, Are H; Jose, Paul E; Karterud, Sigmund

2015-09-01

The Global Assessment of Functioning (GAF) Scale is used in routine clinical practice and research to estimate symptom and functional severity and longitudinal change. Concerns about poor interrater reliability have been raised, and the present study evaluated the effect of a Web-based GAF training program designed to improve interrater reliability in routine clinical practice. Clinicians rated up to 20 vignettes online, and received deviation scores as immediate feedback (i.e., own scores compared with expert raters) after each rating. Growth curves of absolute SD scores across the vignettes were modeled. A linear mixed effects model, using the clinician's deviation scores from expert raters as the dependent variable, indicated an improvement in reliability during training. Moderation by content of scale (symptoms; functioning), scale range (average; extreme), previous experience with GAF rating, profession, and postgraduate training were assessed. Training reduced deviation scores for inexperienced GAF raters, for individuals in clinical professions other than nursing and medicine, and for individuals with no postgraduate specialization. In addition, training was most beneficial for cases with average severity of symptoms compared with cases with extreme severity. The results support the use of Web-based training with feedback routines as a means to improve the reliability of GAF ratings performed by clinicians in mental health practice. These results especially pertain to clinicians in mental health practice who do not have a masters or doctoral degree. (c) 2015 APA, all rights reserved.

Reliability of astronomical records in the Nihongi

NASA Astrophysics Data System (ADS)

Kawabata, Kin-Aki; Tanikawa, Kiyotaka; Soma, Mitsuru

2002-03-01

Records of solar and lunar eclipses and occultations of stars in the Nihongi have been investigated to show their usefulness in answering questions about the long term variability of the Earth's rate of rotation. Results show that reliability of these records depend on the volume of the Nihongi and records in β group of volumes in the classification by H. Mori based on Chinese characters employed as phonetic letters, i.e. Vol. 22 (Empress Suiko), Vol. 23 (Emperor Jomei), and Vol. 29 (Emperor Tenmu), are highly reliable for these studies. Studies of solar eclipses recorded as total eclipses in the Nihongi and the Suishu and an occultation of Mars recorded in the Nihongi show that good agreements can be obtained between descriptions in these Japanese and Chinese historical books and calculations when we adopt TT-UT=3000 sec with correction for tidal term -2.0"/cy2 in the 7th century. Descriptions of solar and lunar eclipses recorded in Vol. 24 (Empress Kogyoku) and Vol. 30 (Empress Jito) are not based on observations but on theoretical predictions. All records of comets, aurorae, volcanic explosions, earthquakes, and tsunami in the Nihongi are described in β group volumes.

Strength and reliability analysis of metal-composite overwrapped pressure vessel

NASA Astrophysics Data System (ADS)

Burov, A. E.; Lepikhin, A. M.; Moskvichev, V. V.

2017-12-01

Metal-composite overwrapped pressure vessels (MCOPV) have found a wide application in aerospace and aeronautical industries. Such vessels should combine impermeability and high weight efficiency with enhanced long-term safety and durability. To meet these requirements, theoretical and experimental studies on the mechanics of deformation and failure of MCOPV are required. In the paper, the analysis on strength, lifetime and reliability of MCOPV is presented. A high performance of the MCOPV is justified by comparing the calculation results with experiment data obtained on full-scale samples.

Small sample estimation of the reliability function for technical products

NASA Astrophysics Data System (ADS)

Lyamets, L. L.; Yakimenko, I. V.; Kanishchev, O. A.; Bliznyuk, O. A.

2017-12-01

It is demonstrated that, in the absence of big statistic samples obtained as a result of testing complex technical products for failure, statistic estimation of the reliability function of initial elements can be made by the moments method. A formal description of the moments method is given and its advantages in the analysis of small censored samples are discussed. A modified algorithm is proposed for the implementation of the moments method with the use of only the moments at which the failures of initial elements occur.

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

NASA Astrophysics Data System (ADS)

Ha, Taesung

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

Applicability and Limitations of Reliability Allocation Methods

NASA Technical Reports Server (NTRS)

Cruz, Jose A.

2016-01-01

Reliability allocation process may be described as the process of assigning reliability requirements to individual components within a system to attain the specified system reliability. For large systems, the allocation process is often performed at different stages of system design. The allocation process often begins at the conceptual stage. As the system design develops, more information about components and the operating environment becomes available, different allocation methods can be considered. Reliability allocation methods are usually divided into two categories: weighting factors and optimal reliability allocation. When properly applied, these methods can produce reasonable approximations. Reliability allocation techniques have limitations and implied assumptions that need to be understood by system engineers. Applying reliability allocation techniques without understanding their limitations and assumptions can produce unrealistic results. This report addresses weighting factors, optimal reliability allocation techniques, and identifies the applicability and limitations of each reliability allocation technique.

Validity and Reliability of Baseline Testing in a Standardized Environment.

PubMed

Higgins, Kathryn L; Caze, Todd; Maerlender, Arthur

2017-08-11

The Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) is a computerized neuropsychological test battery commonly used to determine cognitive recovery from concussion based on comparing post-injury scores to baseline scores. This model is based on the premise that ImPACT baseline test scores are a valid and reliable measure of optimal cognitive function at baseline. Growing evidence suggests that this premise may not be accurate and a large contributor to invalid and unreliable baseline test scores may be the protocol and environment in which baseline tests are administered. This study examined the effects of a standardized environment and administration protocol on the reliability and performance validity of athletes' baseline test scores on ImPACT by comparing scores obtained in two different group-testing settings. Three hundred-sixty one Division 1 cohort-matched collegiate athletes' baseline data were assessed using a variety of indicators of potential performance invalidity; internal reliability was also examined. Thirty-one to thirty-nine percent of the baseline cases had at least one indicator of low performance validity, but there were no significant differences in validity indicators based on environment in which the testing was conducted. Internal consistency reliability scores were in the acceptable to good range, with no significant differences between administration conditions. These results suggest that athletes may be reliably performing at levels lower than their best effort would produce. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Airglow during ionospheric modifications by the sura facility radiation. experimental results obtained in 2010

NASA Astrophysics Data System (ADS)

Grach, S. M.; Klimenko, V. V.; Shindin, A. V.; Nasyrov, I. A.; Sergeev, E. N.; A. Yashnov, V.; A. Pogorelko, N.

2012-06-01

We present the results of studying the structure and dynamics of the HF-heated volume above the Sura facility obtained in 2010 by measurements of ionospheric airglow in the red (λ = 630 nm) and green (λ = 557.7 nm) lines of atomic oxygen. Vertical sounding of the ionosphere (followed by modeling of the pump-wave propagation) and measurements of stimulated electromagnetic emission were used for additional diagnostics of ionospheric parameters and the processes occurring in the heated volume.

Reliable aerial thermography for energy conservation

NASA Technical Reports Server (NTRS)

Jack, J. R.; Bowman, R. L.

1981-01-01

A method for energy conservation, the aerial thermography survey, is discussed. It locates sources of energy losses and wasteful energy management practices. An operational map is presented for clear sky conditions. The map outlines the key environmental conditions conductive to obtaining reliable aerial thermography. The map is developed from defined visual and heat loss discrimination criteria which are quantized based on flat roof heat transfer calculations.

A new approach for improving reliability of personal navigation devices under harsh GNSS signal conditions.

PubMed

Dhital, Anup; Bancroft, Jared B; Lachapelle, Gérard

2013-11-07

In natural and urban canyon environments, Global Navigation Satellite System (GNSS) signals suffer from various challenges such as signal multipath, limited or lack of signal availability and poor geometry. Inertial sensors are often employed to improve the solution continuity under poor GNSS signal quality and availability conditions. Various fault detection schemes have been proposed in the literature to detect and remove biased GNSS measurements to obtain a more reliable navigation solution. However, many of these methods are found to be sub-optimal and often lead to unavailability of reliability measures, mostly because of the improper characterization of the measurement errors. A robust filtering architecture is thus proposed which assumes a heavy-tailed distribution for the measurement errors. Moreover, the proposed filter is capable of adapting to the changing GNSS signal conditions such as when moving from open sky conditions to deep canyons. Results obtained by processing data collected in various GNSS challenged environments show that the proposed scheme provides a robust navigation solution without having to excessively reject usable measurements. The tests reported herein show improvements of nearly 15% and 80% for position accuracy and reliability, respectively, when applying the above approach.

A New Approach for Improving Reliability of Personal Navigation Devices under Harsh GNSS Signal Conditions

PubMed Central

Dhital, Anup; Bancroft, Jared B.; Lachapelle, Gérard

2013-01-01

In natural and urban canyon environments, Global Navigation Satellite System (GNSS) signals suffer from various challenges such as signal multipath, limited or lack of signal availability and poor geometry. Inertial sensors are often employed to improve the solution continuity under poor GNSS signal quality and availability conditions. Various fault detection schemes have been proposed in the literature to detect and remove biased GNSS measurements to obtain a more reliable navigation solution. However, many of these methods are found to be sub-optimal and often lead to unavailability of reliability measures, mostly because of the improper characterization of the measurement errors. A robust filtering architecture is thus proposed which assumes a heavy-tailed distribution for the measurement errors. Moreover, the proposed filter is capable of adapting to the changing GNSS signal conditions such as when moving from open sky conditions to deep canyons. Results obtained by processing data collected in various GNSS challenged environments show that the proposed scheme provides a robust navigation solution without having to excessively reject usable measurements. The tests reported herein show improvements of nearly 15% and 80% for position accuracy and reliability, respectively, when applying the above approach. PMID:24212120

Calculations of reliability predictions for the Apollo spacecraft

NASA Technical Reports Server (NTRS)

Amstadter, B. L.

1966-01-01

A new method of reliability prediction for complex systems is defined. Calculation of both upper and lower bounds are involved, and a procedure for combining the two to yield an approximately true prediction value is presented. Both mission success and crew safety predictions can be calculated, and success probabilities can be obtained for individual mission phases or subsystems. Primary consideration is given to evaluating cases involving zero or one failure per subsystem, and the results of these evaluations are then used for analyzing multiple failure cases. Extensive development is provided for the overall mission success and crew safety equations for both the upper and lower bounds.

The reliability of dietary and lifestyle information obtained from spouses in an elderly chinese population.

PubMed

Liang, Wenbin; Binns, Colin; Lee, Andy H; Huang, Rongsheng; Hu, Delong

2008-01-01

In many health studies of the elderly population, the subjects have cognitive or linguistic impairments, so data need to be collected from surrogates. This study compares dietary and lifestyle information reported by elderly Chinese with those provided by their spouses. Community couples 60 years and older were recruited to participate in an interview. One person from each couple was randomly chosen as the index person. Characteristics concerning the index person were then solicited from that person and separately from his or her spouse using validated questionnaires. For the 128 food items considered, the mean kappa was 0.73 for both frequency (SD 0.18) and amount (SD 0.22) of intake, and more than 70% of the couples had kappa statistics exceeding 0.61. Food items exhibiting high agreement between the spouses include rice, apples, tomatoes, and pork chops. The proportion of perfect agreement was higher than 80% for physical activity, smoking, and tea drinking behaviors. In conclusion, the spouse can serve as a proxy to provide reliable information when his or her partner is unavailable.

Bi-Factor Multidimensional Item Response Theory Modeling for Subscores Estimation, Reliability, and Classification

ERIC Educational Resources Information Center

Md Desa, Zairul Nor Deana

2012-01-01

In recent years, there has been increasing interest in estimating and improving subscore reliability. In this study, the multidimensional item response theory (MIRT) and the bi-factor model were combined to estimate subscores, to obtain subscores reliability, and subscores classification. Both the compensatory and partially compensatory MIRT…

Test-retest reliability of cognitive EEG

NASA Technical Reports Server (NTRS)

McEvoy, L. K.; Smith, M. E.; Gevins, A.

2000-01-01

OBJECTIVE: Task-related EEG is sensitive to changes in cognitive state produced by increased task difficulty and by transient impairment. If task-related EEG has high test-retest reliability, it could be used as part of a clinical test to assess changes in cognitive function. The aim of this study was to determine the reliability of the EEG recorded during the performance of a working memory (WM) task and a psychomotor vigilance task (PVT). METHODS: EEG was recorded while subjects rested quietly and while they performed the tasks. Within session (test-retest interval of approximately 1 h) and between session (test-retest interval of approximately 7 days) reliability was calculated for four EEG components: frontal midline theta at Fz, posterior theta at Pz, and slow and fast alpha at Pz. RESULTS: Task-related EEG was highly reliable within and between sessions (r0.9 for all components in WM task, and r0.8 for all components in the PVT). Resting EEG also showed high reliability, although the magnitude of the correlation was somewhat smaller than that of the task-related EEG (r0.7 for all 4 components). CONCLUSIONS: These results suggest that under appropriate conditions, task-related EEG has sufficient retest reliability for use in assessing clinical changes in cognitive status.

Obtaining land cover changes information from multitemporal analysis of Landsat-TM images: results from a case study in West African dryland

NASA Astrophysics Data System (ADS)

Nutini, F.; Boschetti, M.; Brivio, P. A.; Antoninetti, M.

2012-04-01

The Sahelian belt of West Africa is a semiarid region characterized by wide climate variations, which can in turn affect the livelihood of local populations particularly in rangeland areas, as happens during the dramatic food crisis in the 70-80s caused by rainfall scarcity. The monitoring of natural resources and rainfed agricultural activities, with the aim to provide information to support Sahelian food security action, needs the production of detailed thematic maps as emphasized by several scientific papers. In this framework, a study was conducted to develop a method to exploit time series of remote sensed satellite data to 1) provide reliable land cover (LC) map at local scale in a dry region and 2) obtain a LC change (LCC) map that contribute to identify the plausible causes of local environmental instability. Satellite images used for this work consist in a time series of Landsat Thematic Mapper (TM) (path row 195-50) acquired in the 2000 (6 scenes) and 2007 (9 scenes) from February (Dry season) to September (end of wet season). The study investigates the different contribution provided by spectra information of a single Landsat TM image and by time series of derived NDVI. Different tests have been conducted with different combination of data set (spectral and temporal)in order to identify the best approach to obtain a LC map in five classes of interest: Shrubland, Cultivated Land, Water body, Herbaceous vegetation and Bare soil. The best classification approach is exposed and applied on two years in the last decade. The comparison between this two LC results in land cover change map, that displays the changes of vegetation patterns that have been characterized the area. The discussed results show a largely stable dryland region, but locally characterized by hot-spot of decreasing in natural vegetation inside the rangelands and an increasing of cultivations along fossil valleys where human activities are slightly intense. The discussion shows that this hot

Subject-level reliability analysis of fast fMRI with application to epilepsy.

PubMed

Hao, Yongfu; Khoo, Hui Ming; von Ellenrieder, Nicolas; Gotman, Jean

2017-07-01

Recent studies have applied the new magnetic resonance encephalography (MREG) sequence to the study of interictal epileptic discharges (IEDs) in the electroencephalogram (EEG) of epileptic patients. However, there are no criteria to quantitatively evaluate different processing methods, to properly use the new sequence. We evaluated different processing steps of this new sequence under the common generalized linear model (GLM) framework by assessing the reliability of results. A bootstrap sampling technique was first used to generate multiple replicated data sets; a GLM with different processing steps was then applied to obtain activation maps, and the reliability of these maps was assessed. We applied our analysis in an event-related GLM related to IEDs. A higher reliability was achieved by using a GLM with head motion confound regressor with 24 components rather than the usual 6, with an autoregressive model of order 5 and with a canonical hemodynamic response function (HRF) rather than variable latency or patient-specific HRFs. Comparison of activation with IED field also favored the canonical HRF, consistent with the reliability analysis. The reliability analysis helps to optimize the processing methods for this fast fMRI sequence, in a context in which we do not know the ground truth of activation areas. Magn Reson Med 78:370-382, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Software reliability report

NASA Technical Reports Server (NTRS)

Wilson, Larry

1991-01-01

There are many software reliability models which try to predict future performance of software based on data generated by the debugging process. Unfortunately, the models appear to be unable to account for the random nature of the data. If the same code is debugged multiple times and one of the models is used to make predictions, intolerable variance is observed in the resulting reliability predictions. It is believed that data replication can remove this variance in lab type situations and that it is less than scientific to talk about validating a software reliability model without considering replication. It is also believed that data replication may prove to be cost effective in the real world, thus the research centered on verification of the need for replication and on methodologies for generating replicated data in a cost effective manner. The context of the debugging graph was pursued by simulation and experimentation. Simulation was done for the Basic model and the Log-Poisson model. Reasonable values of the parameters were assigned and used to generate simulated data which is then processed by the models in order to determine limitations on their accuracy. These experiments exploit the existing software and program specimens which are in AIR-LAB to measure the performance of reliability models.

More Reliable Lithium-Sulfur Batteries: Status, Solutions and Prospects.

PubMed

Fang, Ruopian; Zhao, Shiyong; Sun, Zhenhua; Wang, Da-Wei; Cheng, Hui-Ming; Li, Feng

2017-12-01

Lithium-sulfur (Li-S) batteries have attracted tremendous interest because of their high theoretical energy density and cost effectiveness. The target of Li-S battery research is to produce batteries with a high useful energy density that at least outperforms state-of-the-art lithium-ion batteries. However, due to an intrinsic gap between fundamental research and practical applications, the outstanding electrochemical results obtained in most Li-S battery studies indeed correspond to low useful energy densities and are not really suitable for practical requirements. The Li-S battery is a complex device and its useful energy density is determined by a number of design parameters, most of which are often ignored, leading to the failure to meet commercial requirements. The purpose of this review is to discuss how to pave the way for reliable Li-S batteries. First, the current research status of Li-S batteries is briefly reviewed based on statistical information obtained from literature. This includes an analysis of how the various parameters influence the useful energy density and a summary of existing problems in the current Li-S battery research. Possible solutions and some concerns regarding the construction of reliable Li-S batteries are comprehensively discussed. Finally, insights are offered on the future directions and prospects in Li-S battery field. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Obtaining soil hydraulic parameters from data assimilation under different climatic/soil conditions

USDA-ARS?s Scientific Manuscript database

Obtaining reliable soil hydraulic properties is essential to correctly simulating soil water content (SWC), which is a key component of countless applications such as agricultural management, soil remediation, aquifer protection, etc. Soil hydraulic properties can be measured in the laboratory; howe...

Electrical service reliability: the customer perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samsa, M.E.; Hub, K.A.; Krohm, G.C.

1978-09-01

Electric-utility-system reliability criteria have traditionally been established as a matter of utility policy or through long-term engineering practice, generally with no supportive customer cost/benefit analysis as justification. This report presents results of an initial study of the customer perspective toward electric-utility-system reliability, based on critical review of over 20 previous and ongoing efforts to quantify the customer's value of reliable electric service. A possible structure of customer classifications is suggested as a reasonable level of disaggregation for further investigation of customer value, and these groups are characterized in terms of their electricity use patterns. The values that customers assign tomore » reliability are discussed in terms of internal and external cost components. A list of options for effecting changes in customer service reliability is set forth, and some of the many policy issues that could alter customer-service reliability are identified.« less

Creating Highly Reliable Accountable Care Organizations.

PubMed

Vogus, Timothy J; Singer, Sara J

2016-12-01

Accountable Care Organizations' (ACOs) pursuit of the triple aim of higher quality, lower cost, and improved population health has met with mixed results. To improve the design and implementation of ACOs we look to organizations that manage similarly complex, dynamic, and tightly coupled conditions while sustaining exceptional performance known as high-reliability organizations. We describe the key processes through which organizations achieve reliability, the leadership and organizational practices that enable it, and the role that professionals can play when charged with enacting it. Specifically, we present concrete practices and processes from health care organizations pursuing high-reliability and from early ACOs to illustrate how the triple aim may be met by cultivating mindful organizing, practicing reliability-enhancing leadership, and identifying and supporting reliability professionals. We conclude by proposing a set of research questions to advance the study of ACOs and high-reliability research. © The Author(s) 2016.

Study of complete interconnect reliability for a GaAs MMIC power amplifier

NASA Astrophysics Data System (ADS)

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.

Reliability of smartphone-based gait measurements for quantification of physical activity/inactivity levels

PubMed Central

Ebara, Takeshi; Azuma, Ryohei; Shoji, Naoto; Matsukawa, Tsuyoshi; Yamada, Yasuyuki; Akiyama, Tomohiro; Kurihara, Takahiro; Yamada, Shota

2017-01-01

Objectives: Objective measurements using built-in smartphone sensors that can measure physical activity/inactivity in daily working life have the potential to provide a new approach to assessing workers' health effects. The aim of this study was to elucidate the characteristics and reliability of built-in step counting sensors on smartphones for development of an easy-to-use objective measurement tool that can be applied in ergonomics or epidemiological research. Methods: To evaluate the reliability of step counting sensors embedded in seven major smartphone models, the 6-minute walk test was conducted and the following analyses of sensor precision and accuracy were performed: 1) relationship between actual step count and step count detected by sensors, 2) reliability between smartphones of the same model, and 3) false detection rates when sitting during office work, while riding the subway, and driving. Results: On five of the seven models, the inter-class correlations coefficient (ICC (3,1)) showed high reliability with a range of 0.956-0.993. The other two models, however, had ranges of 0.443-0.504 and the relative error ratios of the sensor-detected step count to the actual step count were ±48.7%-49.4%. The level of agreement between the same models was ICC (3,1): 0.992-0.998. The false detection rates differed between the sitting conditions. Conclusions: These results suggest the need for appropriate regulation of step counts measured by sensors, through means such as correction or calibration with a predictive model formula, in order to obtain the highly reliable measurement results that are sought in scientific investigation. PMID:28835575

ASSESSING AND COMBINING RELIABILITY OF PROTEIN INTERACTION SOURCES

PubMed Central

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

2008-01-01

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

The reliability of humerothoracic angles during arm elevation depends on the representation of rotations.

PubMed

López-Pascual, Juan; Cáceres, Magda Liliana; De Rosario, Helios; Page, Álvaro

2016-02-08

The reliability of joint rotation measurements is an issue of major interest, especially in clinical applications. The effect of instrumental errors and soft tissue artifacts on the variability of human motion measures is well known, but the influence of the representation of joint motion has not yet been studied. The aim of the study was to compare the within-subject reliability of three rotation formalisms for the calculation of the shoulder elevation joint angles. Five repetitions of humeral elevation in the scapular plane of 27 healthy subjects were recorded using a stereophotogrammetry system. The humerothoracic joint angles were calculated using the YX'Y" and XZ'Y" Euler angle sequences and the attitude vector. A within-subject repeatability study was performed for the three representations. ICC, SEM and CV were the indices used to estimate the error in the calculation of the angle amplitudes and the angular waveforms with each method. Excellent results were obtained in all representations for the main angle (elevation), but there were remarkable differences for axial rotation and plane of elevation. The YX'Y" sequence generally had the poorest reliability in the secondary angles. The XZ'Y' sequence proved to be the most reliable representation of axial rotation, whereas the attitude vector had the highest reliability in the plane of elevation. These results highlight the importance of selecting the method used to describe the joint motion when within-subjects reliability is an important issue of the experiment. This may be of particular importance when the secondary angles of motions are being studied. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Comparative Evaluation of Mixed Dentition Analysis on Reliability of Cone Beam Computed Tomography Image Compared to Plaster Model.

PubMed

Gowd, Snigdha; Shankar, T; Dash, Samarendra; Sahoo, Nivedita; Chatterjee, Suravi; Mohanty, Pritam

2017-01-01

The aim of the study was to evaluate the reliability of cone beam computed tomography (CBCT) obtained image over plaster model for the assessment of mixed dentition analysis. Thirty CBCT-derived images and thirty plaster models were derived from the dental archives, and Moyer's and Tanaka-Johnston analyses were performed. The data obtained were interpreted and analyzed statistically using SPSS 10.0/PC (SPSS Inc., Chicago, IL, USA). Descriptive and analytical analysis along with Student's t -test was performed to qualitatively evaluate the data and P < 0.05 was considered statistically significant. Statistically, significant results were obtained on data comparison between CBCT-derived images and plaster model; the mean for Moyer's analysis in the left and right lower arch for CBCT and plaster model was 21.2 mm, 21.1 mm and 22.5 mm, 22.5 mm, respectively. CBCT-derived images were less reliable as compared to data obtained directly from plaster model for mixed dentition analysis.

Model uncertainty and multimodel inference in reliability estimation within a longitudinal framework.

PubMed

Alonso, Ariel; Laenen, Annouschka

2013-05-01

Laenen, Alonso, and Molenberghs (2007) and Laenen, Alonso, Molenberghs, and Vangeneugden (2009) proposed a method to assess the reliability of rating scales in a longitudinal context. The methodology is based on hierarchical linear models, and reliability coefficients are derived from the corresponding covariance matrices. However, finding a good parsimonious model to describe complex longitudinal data is a challenging task. Frequently, several models fit the data equally well, raising the problem of model selection uncertainty. When model uncertainty is high one may resort to model averaging, where inferences are based not on one but on an entire set of models. We explored the use of different model building strategies, including model averaging, in reliability estimation. We found that the approach introduced by Laenen et al. (2007, 2009) combined with some of these strategies may yield meaningful results in the presence of high model selection uncertainty and when all models are misspecified, in so far as some of them manage to capture the most salient features of the data. Nonetheless, when all models omit prominent regularities in the data, misleading results may be obtained. The main ideas are further illustrated on a case study in which the reliability of the Hamilton Anxiety Rating Scale is estimated. Importantly, the ambit of model selection uncertainty and model averaging transcends the specific setting studied in the paper and may be of interest in other areas of psychometrics. © 2012 The British Psychological Society.

Neurology objective structured clinical examination reliability using generalizability theory.

PubMed

Blood, Angela D; Park, Yoon Soo; Lukas, Rimas V; Brorson, James R

2015-11-03

This study examines factors affecting reliability, or consistency of assessment scores, from an objective structured clinical examination (OSCE) in neurology through generalizability theory (G theory). Data include assessments from a multistation OSCE taken by 194 medical students at the completion of a neurology clerkship. Facets evaluated in this study include cases, domains, and items. Domains refer to areas of skill (or constructs) that the OSCE measures. G theory is used to estimate variance components associated with each facet, derive reliability, and project the number of cases required to obtain a reliable (consistent, precise) score. Reliability using G theory is moderate (Φ coefficient = 0.61, G coefficient = 0.64). Performance is similar across cases but differs by the particular domain, such that the majority of variance is attributed to the domain. Projections in reliability estimates reveal that students need to participate in 3 OSCE cases in order to increase reliability beyond the 0.70 threshold. This novel use of G theory in evaluating an OSCE in neurology provides meaningful measurement characteristics of the assessment. Differing from prior work in other medical specialties, the cases students were randomly assigned did not influence their OSCE score; rather, scores varied in expected fashion by domain assessed. © 2015 American Academy of Neurology.

Metrics for Assessing the Reliability of a Telemedicine Remote Monitoring System

PubMed Central

Fox, Mark; Papadopoulos, Amy; Crump, Cindy

2013-01-01

Abstract Objective: The goal of this study was to assess using new metrics the reliability of a real-time health monitoring system in homes of older adults. Materials and Methods: The “MobileCare Monitor” system was installed into the homes of nine older adults >75 years of age for a 2-week period. The system consisted of a wireless wristwatch-based monitoring system containing sensors for location, temperature, and impacts and a “panic” button that was connected through a mesh network to third-party wireless devices (blood pressure cuff, pulse oximeter, weight scale, and a survey-administering device). To assess system reliability, daily phone calls instructed participants to conduct system tests and reminded them to fill out surveys and daily diaries. Phone reports and participant diary entries were checked against data received at a secure server. Results: Reliability metrics assessed overall system reliability, data concurrence, study effectiveness, and system usability. Except for the pulse oximeter, system reliability metrics varied between 73% and 92%. Data concurrence for proximal and distal readings exceeded 88%. System usability following the pulse oximeter firmware update varied between 82% and 97%. An estimate of watch-wearing adherence within the home was quite high, about 80%, although given the inability to assess watch-wearing when a participant left the house, adherence likely exceeded the 10 h/day requested time. In total, 3,436 of 3,906 potential measurements were obtained, indicating a study effectiveness of 88%. Conclusions: The system was quite effective in providing accurate remote health data. The different system reliability measures identify important error sources in remote monitoring systems. PMID:23611640

Reliability model of disk arrays RAID-5 with data striping

NASA Astrophysics Data System (ADS)

Rahman, P. A.; D'K Novikova Freyre Shavier, G.

2018-03-01

Within the scope of the this scientific paper, the simplified reliability model of disk arrays RAID-5 (redundant arrays of inexpensive disks) and an advanced reliability model offered by the authors taking into the consideration nonzero time of the faulty disk replacement and different failure rates of disks in normal state of the disk array and in degraded and rebuild states are discussed. The formula obtained by the authors for calculation of the mean time to data loss (MTTDL) of the RAID-5 disk arrays on basis of the advanced model is also presented. Finally, the technique of estimation of the initial reliability parameters, which are used in the reliability model, and the calculation examples of the mean time to data loss of the RAID-5 disk arrays for the different number of disks are also given.

The Reliability of Psychiatric Diagnosis Revisited

PubMed Central

Rankin, Eric; France, Cheryl; El-Missiry, Ahmed; John, Collin

2006-01-01

Background: The authors reviewed the topic of reliability of psychiatric diagnosis from the turn of the 20th century to present. The objectives of this paper are to explore the reasons of unreliability of psychiatric diagnosis and propose ways to improve the reliability of psychiatric diagnosis. Method: The authors reviewed the literature on the concept of reliability of psychiatric diagnosis with emphasis on the impact of interviewing skills, use of diagnostic criteria, and structured interviews on the reliability of psychiatric diagnosis. Results: Causes of diagnostic unreliability are attributed to the patient, the clinician and psychiatric nomenclature. The reliability of psychiatric diagnosis can be enhanced by using diagnostic criteria, defining psychiatric symptoms and structuring the interviews. Conclusions: The authors propose the acronym ‘DR.SED,' which stands for diagnostic criteria, reference definitions, structuring the interview, clinical experience, and data. The authors recommend that clinicians use the DR.SED paradigm to improve the reliability of psychiatric diagnoses. PMID:21103149

Test Reliability at the Individual Level

PubMed Central

Hu, Yueqin; Nesselroade, John R.; Erbacher, Monica K.; Boker, Steven M.; Burt, S. Alexandra; Keel, Pamela K.; Neale, Michael C.; Sisk, Cheryl L.; Klump, Kelly

2016-01-01

Reliability has a long history as one of the key psychometric properties of a test. However, a given test might not measure people equally reliably. Test scores from some individuals may have considerably greater error than others. This study proposed two approaches using intraindividual variation to estimate test reliability for each person. A simulation study suggested that the parallel tests approach and the structural equation modeling approach recovered the simulated reliability coefficients. Then in an empirical study, where forty-five females were measured daily on the Positive and Negative Affect Schedule (PANAS) for 45 consecutive days, separate estimates of reliability were generated for each person. Results showed that reliability estimates of the PANAS varied substantially from person to person. The methods provided in this article apply to tests measuring changeable attributes and require repeated measures across time on each individual. This article also provides a set of parallel forms of PANAS. PMID:28936107

A reliability analysis framework with Monte Carlo simulation for weld structure of crane's beam

NASA Astrophysics Data System (ADS)

Wang, Kefei; Xu, Hongwei; Qu, Fuzheng; Wang, Xin; Shi, Yanjun

2018-04-01

The reliability of the crane product in engineering is the core competitiveness of the product. This paper used Monte Carlo method analyzed the reliability of the weld metal structure of the bridge crane whose limit state function is mathematical expression. Then we obtained the minimum reliable welding feet height value for the welds between cover plate and web plate on main beam in different coefficients of variation. This paper provides a new idea and reference for the growth of the inherent reliability of crane.

Reliability of Maximal Strength Testing in Novice Weightlifters

NASA Technical Reports Server (NTRS)

Loehr, James A.; Lee, Stuart M. C.; Feiveson, Alan H.; Ploutz-Snyder, Lori L.

2009-01-01

The one repetition maximum (1RM) is a criterion measure of muscle strength. However, the reliability of 1RM testing in novice subjects has received little attention. Understanding this information is crucial to accurately interpret changes in muscle strength. To evaluate the test-retest reliability of a squat (SQ), heel raise (HR), and deadlift (DL) 1RM in novice subjects. Twenty healthy males (31 plus or minus 5 y, 179.1 plus or minus 6.1 cm, 81.4 plus or minus 10.6 kg) with no weight training experience in the previous six months participated in four 1RM testing sessions, with each session separated by 5-7 days. SQ and HR 1RM were conducted using a smith machine; DL 1RM was assessed using free weights. Session 1 was considered a familiarization and was not included in the statistical analyses. Repeated measures analysis of variance with Tukey fs post-hoc tests were used to detect between-session differences in 1RM (p.0.05). Test-retest reliability was evaluated by intraclass correlation coefficients (ICC). During Session 2, the SQ and DL 1RM (SQ: 90.2 }4.3, DL: 75.9 }3.3 kg) were less than Session 3 (SQ: 95.3 }4.1, DL: 81.5 plus or minus 3.5 kg) and Session 4 (SQ: 96.6 }4.0, DL: 82.4 }3.9 kg), but there were no differences between Session 3 and Session 4. HR 1RM measured during Session 2 (150.1 }3.7 kg) and Session 3 (152.5 }3.9 kg) were not different from one another, but both were less than Session 4 (157.5 }3.8 kg). The reliability (ICC) of 1RM measures for Sessions 2-4 were 0.88, 0.83, and 0.87, for SQ, HR, and DL, respectively. When considering only Sessions 3 and 4, the reliability was 0.93, 0.91, and 0.86 for SQ, HR, and DL, respectively. One familiarization session and 2 test sessions (for SQ and DL) were required to obtain excellent reliability (ICC greater than or equal to 0.90) in 1RM values with novice subjects. We were unable to attain this level of reliability following 3 HR testing sessions therefore additional sessions may be required to obtain an

Probabilistic Methods for Structural Reliability and Risk

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

2010-01-01

A probabilistic method is used to evaluate the structural reliability and risk of select metallic and composite structures. The method is a multiscale, multifunctional and it is based on the most elemental level. A multifactor interaction model is used to describe the material properties which are subsequently evaluated probabilistically. The metallic structure is a two rotor aircraft engine, while the composite structures consist of laminated plies (multiscale) and the properties of each ply are the multifunctional representation. The structural component is modeled by finite element. The solution method for structural responses is obtained by an updated simulation scheme. The results show that the risk for the two rotor engine is about 0.0001 and the composite built-up structure is also 0.0001.

Probabilistic Methods for Structural Reliability and Risk

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

2008-01-01

A probabilistic method is used to evaluate the structural reliability and risk of select metallic and composite structures. The method is a multiscale, multifunctional and it is based on the most elemental level. A multi-factor interaction model is used to describe the material properties which are subsequently evaluated probabilistically. The metallic structure is a two rotor aircraft engine, while the composite structures consist of laminated plies (multiscale) and the properties of each ply are the multifunctional representation. The structural component is modeled by finite element. The solution method for structural responses is obtained by an updated simulation scheme. The results show that the risk for the two rotor engine is about 0.0001 and the composite built-up structure is also 0.0001.

The Reliability of Results from National Tests, Public Examinations, and Vocational Qualifications in England

ERIC Educational Resources Information Center

He, Qingping; Opposs, Dennis

2012-01-01

National tests, public examinations, and vocational qualifications in England are used for a variety of purposes, including the certification of individual learners in different subject areas and the accountability of individual professionals and institutions. However, there has been ongoing debate about the reliability and validity of their…

75 FR 71613 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-24

... Reliability Standards. The proposed Reliability Standards were designed to prevent instability, uncontrolled... Reliability Standards.\\2\\ The proposed Reliability Standards were designed to prevent instability... the SOLs, which if exceeded, could expose a widespread area of the bulk electric system to instability...

Reliability of VEP Recordings Using Chronically Implanted Screw Electrodes in Mice

PubMed Central

Makowiecki, Kalina; Garrett, Andrew; Clark, Vince; Graham, Stuart L.; Rodger, Jennifer

2015-01-01

Purpose: Visual evoked potentials (VEPs) are widely used to objectively assess visual system function in animal models of ophthalmological diseases. Although use of chronically implanted electrodes is common in longitudinal VEP studies using rodent models, reliability of recordings over time has not been assessed. We compared VEPs 1 and 7 days after electrode implantation in the adult mouse. We also examined stimulus-independent changes over time, by assessing electroencephalogram (EEG) power and approximate entropy of the EEG signal. Methods: Stainless steel screws (600-μm diameter) were implanted into the skull overlying the right visual cortex and the orbitofrontal cortex of adult mice (C57Bl/6J, n = 7). Animals were reanesthetized 1 and 7 days after implantation to record VEP responses (flashed gratings) and EEG activity. Brain sections were stained for glial activation (GFAP) and cell death (TUNEL). Results: Reliability analysis, using intraclass correlation coefficients, showed VEP recordings had high reliability within the same session, regardless of time after electrode implantation and peak latencies and approximate entropy of the EEG did not change significantly with time. However, there was poorer reliability between recordings obtained on different days, and a significant decrease in VEP amplitudes and EEG power. This amplitude decrease could be normalized by scaling to EEG power (within-subjects). Furthermore, glial activation was present at both time points but there was no evidence of cell death. Conclusions: These results indicate that VEP responses can be reliably recorded even after a relatively short recovery period but decrease response peak amplitude over time. Although scaling the VEP trace to EEG power normalized this decrease, our results highlight that time-dependent cortical excitability changes are an important consideration in longitudinal VEP studies. Translational Relevance: This study shows changes in VEP characteristics over time in

Online patient information on Vagus Nerve Stimulation: How reliable is it for facilitating shared decision making?

PubMed

Ved, Ronak; Cobbold, Naomi; Igbagiri, Kueni; Willis, Mark; Leach, Paul; Zaben, Malik

2017-08-01

This study evaluates the quality of information available on the internet for carers of children with epilepsy considering treatment with Vagus Nerve Stimulation (VNS). Selected key phrases were entered into two popular search engines (Google™, Yahoo™). These phrases were: "Vagus nerve stimulator", alone and in combination with "childhood epilepsy", "paediatric epilepsy" and "epilepsy in childhood"; "VNS", and "VNS epilepsy". The first 50 hits per search were then screened. Of 600 identified sites, duplicated (262), irrelevant (230) and inaccessible (15) results were excluded. 93 websites were identified for evaluation using the DISCERN instrument, an online validation tool for patient information websites. The mean DISCERN score of all analysed websites was 39/80 (49%; SD 13.5). This equates to Fair to borderline Poor global quality, (Excellent=80-63; Good=62-51; Fair=50-39; Poor=38-27; Very poor=26-15). None of the analysed sites obtained an Excellent quality rating. 13% (12) obtained a Good score, 40% (37) obtained an Average score, 35% (33) obtained a Poor score, and 12% (11) obtained a Very poor score. The cohort of websites scored particularly poorly on assessment of whether reliable, holistic information was presented, for instance provision of reliable sources, (28%, SD 18) and discussion of alternative treatments, (30%, SD 14). To facilitate patient-centred shared decision-making, high quality information needs to be available for patients and families considering VNS. This study identifies that such information is difficult to locate on the internet. There is a need to develop focussed and reliable online patient resources for VNS. Copyright © 2017 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Reliability of smartphone-based gait measurements for quantification of physical activity/inactivity levels.

PubMed

Ebara, Takeshi; Azuma, Ryohei; Shoji, Naoto; Matsukawa, Tsuyoshi; Yamada, Yasuyuki; Akiyama, Tomohiro; Kurihara, Takahiro; Yamada, Shota

2017-11-25

Objective measurements using built-in smartphone sensors that can measure physical activity/inactivity in daily working life have the potential to provide a new approach to assessing workers' health effects. The aim of this study was to elucidate the characteristics and reliability of built-in step counting sensors on smartphones for development of an easy-to-use objective measurement tool that can be applied in ergonomics or epidemiological research. To evaluate the reliability of step counting sensors embedded in seven major smartphone models, the 6-minute walk test was conducted and the following analyses of sensor precision and accuracy were performed: 1) relationship between actual step count and step count detected by sensors, 2) reliability between smartphones of the same model, and 3) false detection rates when sitting during office work, while riding the subway, and driving. On five of the seven models, the inter-class correlations coefficient (ICC (3,1) ) showed high reliability with a range of 0.956-0.993. The other two models, however, had ranges of 0.443-0.504 and the relative error ratios of the sensor-detected step count to the actual step count were ±48.7%-49.4%. The level of agreement between the same models was ICC (3,1) : 0.992-0.998. The false detection rates differed between the sitting conditions. These results suggest the need for appropriate regulation of step counts measured by sensors, through means such as correction or calibration with a predictive model formula, in order to obtain the highly reliable measurement results that are sought in scientific investigation.

Electrochemical cell for obtaining oxygen from carbon dioxide atmospheres

NASA Technical Reports Server (NTRS)

Hooker, M. W.; Rast, H. E.; Rogers, D. K.

1989-01-01

For manned missions to Mars to become a reality, an efficient and reliable means of obtaining oxygen from the carbon dioxide-rich atmosphere will be required. Otherwise, the high cost of transporting the oxygen needed to sustain the astronauts will severely restrict the expedition to the martian surface. Recently, the use of electrochemical devices has been explored as a means of obtaining oxygen from the carbon dioxide-rich atmosphere. In these devices, oxygen ions diffuse through solid oxide membranes, thus, separating oxygen from the other gases presented. This phenomenon has only recently been explored as a means of obtaining large quantities of oxygen from toxic atmospheres, although first observed by Walter nernst in 1899. Nernst observed that stabilized zirconia will conduct oxygen ions when an electrical potential is applied across metallic electrodes applied to the ceramic membrane. Diatomic oxygen molecules are dissociated at the positive electrode/electrolyte interface. The oxygen ions enter the ceramic body due to the ion density gradient which is produced by the electrical potential across the electrolytic membrane. Once the ions have diffused through the membrane, they reform diatomic oxygen molecules at the anode. The separation of oxygen from carbon dioxide is achieved by the combination of thermal and electrochemical processes. The thermal decomposition of carbon dioxide (at 1000 C) results in the production of carbon monoxide and oxygen by the reaction.

Heroic Reliability Improvement in Manned Space Systems

NASA Technical Reports Server (NTRS)

Jones, Harry W.

2017-01-01

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

Reliability Growth and Its Applications to Dormant Reliability

DTIC Science & Technology

1981-12-01

ability to make projection about future reli- ability (Rof 9:41-42). Barlow and Scheuer Model. Richard E. Barlow and Ernest M. Sch~uvr, of the University...Reliability Growth Prediction Models," Operations Research, 18(l):S2-6S (January/February 1970). 7. Bauer, John, William Hadley, and Robert Dietz... Texarkana , Texas, May 1973. (AD 768 119). 10. Bonis, Austin J. "Reliability Growth Curves for One Shot Devices," Proceedings 1977 Annual Reliability and

Accurate, robust and reliable calculations of Poisson-Boltzmann binding energies

PubMed Central

Nguyen, Duc D.; Wang, Bao

2017-01-01

Poisson-Boltzmann (PB) model is one of the most popular implicit solvent models in biophysical modeling and computation. The ability of providing accurate and reliable PB estimation of electrostatic solvation free energy, ΔGel, and binding free energy, ΔΔGel, is important to computational biophysics and biochemistry. In this work, we investigate the grid dependence of our PB solver (MIBPB) with SESs for estimating both electrostatic solvation free energies and electrostatic binding free energies. It is found that the relative absolute error of ΔGel obtained at the grid spacing of 1.0 Å compared to ΔGel at 0.2 Å averaged over 153 molecules is less than 0.2%. Our results indicate that the use of grid spacing 0.6 Å ensures accuracy and reliability in ΔΔGel calculation. In fact, the grid spacing of 1.1 Å appears to deliver adequate accuracy for high throughput screening. PMID:28211071

Reliability and discriminatory power of methods for dental plaque quantification

PubMed Central

RAGGIO, Daniela Prócida; BRAGA, Mariana Minatel; RODRIGUES, Jonas Almeida; FREITAS, Patrícia Moreira; IMPARATO, José Carlos Pettorossi; MENDES, Fausto Medeiros

2010-01-01

Objective This in situ study evaluated the discriminatory power and reliability of methods of dental plaque quantification and the relationship between visual indices (VI) and fluorescence camera (FC) to detect plaque. Material and Methods Six volunteers used palatal appliances with six bovine enamel blocks presenting different stages of plaque accumulation. The presence of plaque with and without disclosing was assessed using VI. Images were obtained with FC and digital camera in both conditions. The area covered by plaque was assessed. Examinations were done by two independent examiners. Data were analyzed by Kruskal-Wallis and Kappa tests to compare different conditions of samples and to assess the inter-examiner reproducibility. Results Some methods presented adequate reproducibility. The Turesky index and the assessment of area covered by disclosed plaque in the FC images presented the highest discriminatory powers. Conclusions The Turesky index and images with FC with disclosing present good reliability and discriminatory power in quantifying dental plaque. PMID:20485931

Oximeter reliability in a subzero environment.

PubMed

Macnab, A J; Smith, M; Phillips, N; Smart, P

1996-11-01

Pulse oximeters optimize care in the pre-hospital setting. As British Columbia ambulance teams often provide care in subzero temperatures, we conducted a study to determine the reliability of 3 commercially-available portable oximeters in a subzero environment. We hypothesized that there is no significant difference between SaO2 readings obtained using a pulse oximeter at room temperature and a pulse oximeter operating at sub-zero temperatures. Subjects were stable normothermic children in intensive care on Hewlett Packard monitors (control unit) at room temperature. The test units were packed in dry ice in an insulated bin (temperature - 15 degrees C to -30 degrees C) and their sensors placed on the subjects, contralateral to the control sensors. Data were collected simultaneously from test and control units immediately following validation of control unit values by co-oximetry (blood gas). No data were unacceptable. Two units (Propaq 106EC and Nonin 8500N) functioned well to < -15 degrees C, providing data comparable to those obtained from the control unit (p < 0.001). The Siemens Micro O2 did not function at the temperatures tested. Monitor users who require equipment to function in subzero environments (military, Coast Guard, Mountain Rescue) should ensure that function is reliable, and could test units using this method.

Reliability of tristimulus colourimetry in the assessment of cutaneous bruise colour.

PubMed

Scafide, Katherine N; Sheridan, Daniel J; Taylor, Laura A; Hayat, Matthew J

2016-06-01

Bruising is one of the most common types of injury clinicians observe among victims of violence and other trauma patients. However, research has shown commonly used qualitative description of cutaneous bruise colour via the naked eye is subjective and unreliable. No published work has formally evaluated the reliability of tristimulus colourimetry as an alternative for assessing bruise colour, despite its clinical and research applications in accurately assessing skin colour. The purpose of this study was to systematically evaluate the test-retest and inter-observer reliability of tristimulus colourimetry in the assessment of cutaneous bruise colour. Two researchers obtained repeated tristimulus colourimetry measures of cutaneous bruises with participants of diverse skin colour. Measures were obtained using the Minolta CR-400 Chomameter. Commission Internationale d'Eclairage (CIE) L*a*b* colour space was used. Data was analysed using intraclass correlation coefficients (ICC), Cronbach's alpha, and minimal detectable change (MDC) on all three L*a*b* values. The colorimeter demonstrated excellent test-retest or intra-rater reliability (L* ICC=0.999; a* ICC=0.973; b* ICC=0.892) and inter-rater reliability (L* ICC=0.997; a* ICC=0.976; b* ICC=0.982). With consistent placement, the tristimulus colourimetry is reliable for the objective assessment and documentation of cutaneous bruise colour for purposes of clinical practice and research. Recommendations for use in practice/research are provided. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recent advances in computational structural reliability analysis methods

NASA Astrophysics Data System (ADS)

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

1993-10-01

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

Recent advances in computational structural reliability analysis methods

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Computational methods for efficient structural reliability and reliability sensitivity analysis

NASA Technical Reports Server (NTRS)

Wu, Y.-T.

1993-01-01

This paper presents recent developments in efficient structural reliability analysis methods. The paper proposes an efficient, adaptive importance sampling (AIS) method that can be used to compute reliability and reliability sensitivities. The AIS approach uses a sampling density that is proportional to the joint PDF of the random variables. Starting from an initial approximate failure domain, sampling proceeds adaptively and incrementally with the goal of reaching a sampling domain that is slightly greater than the failure domain to minimize over-sampling in the safe region. Several reliability sensitivity coefficients are proposed that can be computed directly and easily from the above AIS-based failure points. These probability sensitivities can be used for identifying key random variables and for adjusting design to achieve reliability-based objectives. The proposed AIS methodology is demonstrated using a turbine blade reliability analysis problem.

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

NASA Technical Reports Server (NTRS)

Hou, Gene J.-W; Newman, Perry A. (Technical Monitor)

2004-01-01

A major step in a most probable point (MPP)-based method for reliability analysis is to determine the MPP. This is usually accomplished by using an optimization search algorithm. The minimum distance associated with the MPP provides a measurement of safety probability, which can be obtained by approximate probability integration methods such as FORM or SORM. The reliability sensitivity equations are derived first in this paper, based on the derivatives of the optimal solution. Examples are provided later to demonstrate the use of these derivatives for better reliability analysis and reliability-based design optimization (RBDO).

A reliability evaluation methodology for memory chips for space applications when sample size is small

NASA Technical Reports Server (NTRS)

Chen, Y.; Nguyen, D.; Guertin, S.; Berstein, J.; White, M.; Menke, R.; Kayali, S.

2003-01-01

This paper presents a reliability evaluation methodology to obtain the statistical reliability information of memory chips for space applications when the test sample size needs to be kept small because of the high cost of the radiation hardness memories.

Flight control electronics reliability/maintenance study

NASA Technical Reports Server (NTRS)

Dade, W. W.; Edwards, R. H.; Katt, G. T.; Mcclellan, K. L.; Shomber, H. A.

1977-01-01

Collection and analysis of data are reported that concern the reliability and maintenance experience of flight control system electronics currently in use on passenger carrying jet aircraft. Two airlines B-747 airplane fleets were analyzed to assess the component reliability, system functional reliability, and achieved availability of the CAT II configuration flight control system. Also assessed were the costs generated by this system in the categories of spare equipment, schedule irregularity, and line and shop maintenance. The results indicate that although there is a marked difference in the geographic location and route pattern between the airlines studied, there is a close similarity in the reliability and the maintenance costs associated with the flight control electronics.

Influence of pansharpening techniques in obtaining accurate vegetation thematic maps

NASA Astrophysics Data System (ADS)

Ibarrola-Ulzurrun, Edurne; Gonzalo-Martin, Consuelo; Marcello-Ruiz, Javier

2016-10-01

In last decades, there have been a decline in natural resources, becoming important to develop reliable methodologies for their management. The appearance of very high resolution sensors has offered a practical and cost-effective means for a good environmental management. In this context, improvements are needed for obtaining higher quality of the information available in order to get reliable classified images. Thus, pansharpening enhances the spatial resolution of the multispectral band by incorporating information from the panchromatic image. The main goal in the study is to implement pixel and object-based classification techniques applied to the fused imagery using different pansharpening algorithms and the evaluation of thematic maps generated that serve to obtain accurate information for the conservation of natural resources. A vulnerable heterogenic ecosystem from Canary Islands (Spain) was chosen, Teide National Park, and Worldview-2 high resolution imagery was employed. The classes considered of interest were set by the National Park conservation managers. 7 pansharpening techniques (GS, FIHS, HCS, MTF based, Wavelet `à trous' and Weighted Wavelet `à trous' through Fractal Dimension Maps) were chosen in order to improve the data quality with the goal to analyze the vegetation classes. Next, different classification algorithms were applied at pixel-based and object-based approach, moreover, an accuracy assessment of the different thematic maps obtained were performed. The highest classification accuracy was obtained applying Support Vector Machine classifier at object-based approach in the Weighted Wavelet `à trous' through Fractal Dimension Maps fused image. Finally, highlight the difficulty of the classification in Teide ecosystem due to the heterogeneity and the small size of the species. Thus, it is important to obtain accurate thematic maps for further studies in the management and conservation of natural resources.

Software Reliability 2002

NASA Technical Reports Server (NTRS)

Wallace, Dolores R.

2003-01-01

In FY01 we learned that hardware reliability models need substantial changes to account for differences in software, thus making software reliability measurements more effective, accurate, and easier to apply. These reliability models are generally based on familiar distributions or parametric methods. An obvious question is 'What new statistical and probability models can be developed using non-parametric and distribution-free methods instead of the traditional parametric method?" Two approaches to software reliability engineering appear somewhat promising. The first study, begin in FY01, is based in hardware reliability, a very well established science that has many aspects that can be applied to software. This research effort has investigated mathematical aspects of hardware reliability and has identified those applicable to software. Currently the research effort is applying and testing these approaches to software reliability measurement, These parametric models require much project data that may be difficult to apply and interpret. Projects at GSFC are often complex in both technology and schedules. Assessing and estimating reliability of the final system is extremely difficult when various subsystems are tested and completed long before others. Parametric and distribution free techniques may offer a new and accurate way of modeling failure time and other project data to provide earlier and more accurate estimates of system reliability.

Detection of β-Thalassemia Carriers by Red Cell Parameters Obtained from Automatic Counters using Mathematical Formulas

PubMed Central

Roth, Idit Lachover; Lachover, Boaz; Koren, Guy; Levin, Carina; Zalman, Luci; Koren, Ariel

2018-01-01

Background β-thalassemia major is a severe disease with high morbidity. The world prevalence of carriers is around 1.5–7%. The present study aimed to find a reliable formula for detecting β-thalassemia carriers using an extensive database of more than 22,000 samples obtained from a homogeneous population of childbearing age women with 3161 (13.6%) of β-thalassemia carriers and to check previously published formulas. Methods We applied a mathematical method based on the support vector machine (SVM) algorithm in the search for a reliable formula that can differentiate between thalassemia carriers and non-carriers, including normal counts or counts suspected to belong to iron-deficient women. Results Shine’s formula and our SVM formula showed >98% sensitivity and >99.77% negative predictive value (NPV). All other published formulas gave inferior results. Conclusions We found a reliable formula that can be incorporated into any automatic blood counter to alert health providers to the possibility of a woman being a β-thalassemia carrier. A further simple hemoglobin characterization by HPLC analysis should be performed to confirm the diagnosis, and subsequent family studies should be carried out. Our SVM formula is currently limited to women of fertility age until further analysis in other groups can be performed. PMID:29326805

Integrating field methodology and web-based data collection to assess the reliability of the Alcohol Use Disorders Identification Test (AUDIT).

PubMed

Celio, Mark A; Vetter-O'Hagen, Courtney S; Lisman, Stephen A; Johansen, Gerard E; Spear, Linda P

2011-12-01

Field methodologies offer a unique opportunity to collect ecologically valid data on alcohol use and its associated problems within natural drinking environments. However, limitations in follow-up data collection methods have left unanswered questions regarding the psychometric properties of field-based measures. The aim of the current study is to evaluate the reliability of self-report data collected in a naturally occurring environment - as indexed by the Alcohol Use Disorders Identification Test (AUDIT) - compared to self-report data obtained through an innovative web-based follow-up procedure. Individuals recruited outside of bars (N=170; mean age=21; range 18-32) provided a BAC sample and completed a self-administered survey packet that included the AUDIT. BAC feedback was provided anonymously through a dedicated web page. Upon sign in, follow-up participants (n=89; 52%) were again asked to complete the AUDIT before receiving their BAC feedback. Reliability analyses demonstrated that AUDIT scores - both continuous and dichotomized at the standard cut-point - were stable across field- and web-based administrations. These results suggest that self-report data obtained from acutely intoxicated individuals in naturally occurring environments are reliable when compared to web-based data obtained after a brief follow-up interval. Furthermore, the results demonstrate the feasibility, utility, and potential of integrating field methods and web-based data collection procedures. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Reliable Breakdown Obtained in Silicon Carbide Rectifiers

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.

1997-01-01

The High Temperature Integrated Electronics and Sensor (HTIES) Program at the NASA Lewis Research Center is currently developing silicon carbide (SiC) for use in harsh conditions where silicon, the semiconductor used in nearly all of today's electronics, cannot function. Silicon carbide's demonstrated ability to function under extreme high-temperature, high-power, and/or high-radiation conditions will enable significant improvements to a far-ranging variety of applications and systems. These range from improved high-voltage switching for energy savings in public electric power distribution and electric vehicles, to more powerful microwave electronics for radar and cellular communications, to sensor and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines.

The role of test-retest reliability in measuring individual and group differences in executive functioning.

PubMed

Paap, Kenneth R; Sawi, Oliver

2016-12-01

Studies testing for individual or group differences in executive functioning can be compromised by unknown test-retest reliability. Test-retest reliabilities across an interval of about one week were obtained from performance in the antisaccade, flanker, Simon, and color-shape switching tasks. There is a general trade-off between the greater reliability of single mean RT measures, and the greater process purity of measures based on contrasts between mean RTs in two conditions. The individual differences in RT model recently developed by Miller and Ulrich was used to evaluate the trade-off. Test-retest reliability was statistically significant for 11 of the 12 measures, but was of moderate size, at best, for the difference scores. The test-retest reliabilities for the Simon and flanker interference scores were lower than those for switching costs. Standard practice evaluates the reliability of executive-functioning measures using split-half methods based on data obtained in a single day. Our test-retest measures of reliability are lower, especially for difference scores. These reliability measures must also take into account possible day effects that classical test theory assumes do not occur. Measures based on single mean RTs tend to have acceptable levels of reliability and convergent validity, but are "impure" measures of specific executive functions. The individual differences in RT model shows that the impurity problem is worse than typically assumed. However, the "purer" measures based on difference scores have low convergent validity that is partly caused by deficiencies in test-retest reliability. Copyright © 2016 Elsevier B.V. All rights reserved.

Validity and Reliability of Spine Rasterstereography in Patients With Adolescent Idiopathic Scoliosis.

PubMed

Tabard-Fougère, Anne; Bonnefoy-Mazure, Alice; Hanquinet, Sylviane; Lascombes, Pierre; Armand, Stéphane; Dayer, Romain

2017-01-15

Test-retest study. This study aimed to evaluate the validity and reliability of rasterstereography in patients with adolescent idiopathic scoliosis (AIS) with a major curve Cobb angle (CA) between 10° and 40° for frontal, sagittal, and transverse parameters. Previous studies evaluating the validity and reliability of rasterstereography concluded that this technique had good accuracy compared with radiographs and a high intra- and interday reliability in healthy volunteers. To the best of our knowledge, the validity and reliability have not been assessed in AIS patients. Thirty-five adolescents with AIS (male = 13) aged 13.1 ± 2.0 years were included. To evaluate the validity of the scoliosis angle (SA) provided by rasterstereography, a comparison (t test, Pearson correlation) was performed with the CA obtained using 2D EOS® radiography (XR). Three rasterstereographic repeated measurements were independently performed by two operators on the same day (interrater reliability) and again by the first operator 1 week later (intrarater reliability). The variables of interest were the SA, lumbar lordosis, and thoracic kyphosis angle, trunk length, pelvic obliquity, and maximum, root mean square and amplitude of vertebral rotations. The data analyses used intraclass correlation coefficients (ICCs). The CA and SA were strongly correlated (R = 0.70) and were nonsignificantly different (P = 0.60). The intrarater reliability (same day: ICC [1, 1], n = 35; 1 week later: ICC [1, 3], n = 28) and interrater reliability (ICC [3, 3], n = 16) were globally excellent (ICC > 0.75) except for the assessment of pelvic obliquity. This study showed that the rasterstereographic system allows for the evaluation of AIS patients with a good validity compared with XR with an overall excellent intra- and interrater reliability. Based on these results, this automatic, fast, and noninvasive system can be used for monitoring the evolution of AIS in growing

On the next generation of reliability analysis tools

NASA Technical Reports Server (NTRS)

Babcock, Philip S., IV; Leong, Frank; Gai, Eli

1987-01-01

The current generation of reliability analysis tools concentrates on improving the efficiency of the description and solution of the fault-handling processes and providing a solution algorithm for the full system model. The tools have improved user efficiency in these areas to the extent that the problem of constructing the fault-occurrence model is now the major analysis bottleneck. For the next generation of reliability tools, it is proposed that techniques be developed to improve the efficiency of the fault-occurrence model generation and input. Further, the goal is to provide an environment permitting a user to provide a top-down design description of the system from which a Markov reliability model is automatically constructed. Thus, the user is relieved of the tedious and error-prone process of model construction, permitting an efficient exploration of the design space, and an independent validation of the system's operation is obtained. An additional benefit of automating the model construction process is the opportunity to reduce the specialized knowledge required. Hence, the user need only be an expert in the system he is analyzing; the expertise in reliability analysis techniques is supplied.

Reliability of Leg and Vertical Stiffness During High Speed Treadmill Running.

PubMed

Pappas, Panagiotis; Dallas, Giorgos; Paradisis, Giorgos

2017-04-01

In research, the accurate and reliable measurement of leg and vertical stiffness could contribute to valid interpretations. The current study aimed at determining the intraparticipant variability (ie, intraday and interday reliabilities) of leg and vertical stiffness, as well as related parameters, during high speed treadmill running, using the "sine-wave" method. Thirty-one males ran on a treadmill at 6.67 m∙s -1 , and the contact and flight times were measured. To determine the intraday reliability, three 10-s running bouts with 10-min recovery were performed. In addition, to examine the interday reliability, three 10-s running bouts on 3 separate days with 48-h interbout intervals were performed. The reliability statistics included repeated-measure analysis of variance, average intertrial correlations, intraclass correlation coefficients (ICCs), Cronbach's α reliability coefficient, and the coefficient of variation (CV%). Both intraday and interday reliabilities were high for leg and vertical stiffness (ICC > 0.939 and CV < 4.3%), as well as related variables (ICC > 0.934 and CV < 3.9%). It was thus inferred that the measurements of leg and vertical stiffness, as well as the related parameters obtained using the "sine-wave" method during treadmill running at 6.67 m∙s -1 , were highly reliable, both within and across days.

A reliability analysis of the revised competitiveness index.

PubMed

Harris, Paul B; Houston, John M

2010-06-01

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

Reliable contact fabrication on nanostructured Bi2Te3-based thermoelectric materials.

PubMed

Feng, Shien-Ping; Chang, Ya-Huei; Yang, Jian; Poudel, Bed; Yu, Bo; Ren, Zhifeng; Chen, Gang

2013-05-14

A cost-effective and reliable Ni-Au contact on nanostructured Bi2Te3-based alloys for a solar thermoelectric generator (STEG) is reported. The use of MPS SAMs creates a strong covalent binding and more nucleation sites with even distribution for electroplating contact electrodes on nanostructured thermoelectric materials. A reliable high-performance flat-panel STEG can be obtained by using this new method.

VizieR Online Data Catalog: Redshift reliability flags (VVDS data) (Jamal+, 2018)

NASA Astrophysics Data System (ADS)

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

2017-09-01

The VIMOS VLT Deep Survey (Le Fevre et al. 2013A&A...559A..14L) is a combination of 3 i-band magnitude limited surveys: Wide (17.5<=iAB<=22.5; 8.6deg2), Deep (17.5<=iAB<=24; 0.6deg2) and Ultra-Deep (23<=iAB<=24.75; 512arcmin2), that produced a total of 35526 spectroscopic galaxy redshifts between 0 and 6.7 (22434 in Wide, 12051 in Deep and 1041 in UDeep). We supplement spectra of the VIMOS VLT Deep Survey (VVDS) with newly-defined redshift reliability flags obtained from clustering (unsupervised classification in Machine Learning) a set of descriptors from individual zPDFs. In this paper, we exploit a set of 24519 spectra from the VVDS database. After computing zPDFs for each individual spectrum, a set of (8) descriptors of the zPDF are extracted to build a feature matrix X (dimension = 24519 rows, 8 columns). Then, we use a clustering (unsupervised algorithms in Machine Learning) algorithm to partition the feature space into distinct clusters (5 clusters: C1,C2,C3,C4,C5), each depicting a different level of confidence to associate with the measured redshift zMAP (Maximum-A-Posteriori estimate that corresponds to the maximum of the redshift PDF). The clustering results (C1,C2,C3,C4,C5) reported in the table are those used in the paper (Jamal et al, 2017) to present the new methodology of automating the zspec reliability assessment. In particular, we would like to point out that they were obtained from first tests conducted on the VVDS spectroscopic data (end of 2016). Therefore, the table does not depict immutable results (on-going improvements). Future updates of the VVDS redshift reliability flags can be expected. (1 data file).

Reliability analysis of interdependent lattices

NASA Astrophysics Data System (ADS)

Limiao, Zhang; Daqing, Li; Pengju, Qin; Bowen, Fu; Yinan, Jiang; Zio, Enrico; Rui, Kang

2016-06-01

Network reliability analysis has drawn much attention recently due to the risks of catastrophic damage in networked infrastructures. These infrastructures are dependent on each other as a result of various interactions. However, most of the reliability analyses of these interdependent networks do not consider spatial constraints, which are found important for robustness of infrastructures including power grid and transport systems. Here we study the reliability properties of interdependent lattices with different ranges of spatial constraints. Our study shows that interdependent lattices with strong spatial constraints are more resilient than interdependent Erdös-Rényi networks. There exists an intermediate range of spatial constraints, at which the interdependent lattices have minimal resilience.

B-52 stability augmentation system reliability

NASA Technical Reports Server (NTRS)

Bowling, T. C.; Key, L. W.

1976-01-01

The B-52 SAS (Stability Augmentation System) was developed and retrofitted to nearly 300 aircraft. It actively controls B-52 structural bending, provides improved yaw and pitch damping through sensors and electronic control channels, and puts complete reliance on hydraulic control power for rudder and elevators. The system has experienced over 300,000 flight hours and has exhibited service reliability comparable to the results of the reliability test program. Development experience points out numerous lessons with potential application in the mechanization and development of advanced technology control systems of high reliability.

Test-re-test reliability and inter-rater reliability of a digital pelvic inclinometer in young, healthy males and females.

PubMed

Beardsley, Chris; Egerton, Tim; Skinner, Brendon

2016-01-01

Objective. The purpose of this study was to investigate the reliability of a digital pelvic inclinometer (DPI) for measuring sagittal plane pelvic tilt in 18 young, healthy males and females. Method. The inter-rater reliability and test-re-test reliabilities of the DPI for measuring pelvic tilt in standing on both the right and left sides of the pelvis were measured by two raters carrying out two rating sessions of the same subjects, three weeks apart. Results. For measuring pelvic tilt, inter-rater reliability was designated as good on both sides (ICC = 0.81-0.88), test-re-test reliability within a single rating session was designated as good on both sides (ICC = 0.88-0.95), and test-re-test reliability between two rating sessions was designated as moderate on the left side (ICC = 0.65) and good on the right side (ICC = 0.85). Conclusion. Inter-rater reliability and test-re-test reliability within a single rating session of the DPI in measuring pelvic tilt were both good, while test-re-test reliability between rating sessions was moderate-to-good. Caution is required regarding the interpretation of the test-re-test reliability within a single rating session, as the raters were not blinded. Further research is required to establish validity.

Optimization of the parameters for obtaining zirconia-alumina coatings, made by flame spraying from results of numerical simulation

NASA Astrophysics Data System (ADS)

Ferrer, M.; Vargas, F.; Peña, G.

2017-12-01

The K-Sommerfeld values (K) and the melting percentage (% F) obtained by numerical simulation using the Jets et Poudres software were used to find the projection parameters of zirconia-alumina coatings by thermal spraying flame, in order to obtain coatings with good morphological and structural properties to be used as thermal insulation. The experimental results show the relationship between the Sommerfeld parameter and the porosity of the zirconia-alumina coatings. It is found that the lowest porosity is obtained when the K-Sommerfeld value is close to 45 with an oxidant flame, on the contrary, when superoxidant flames are used K values are close 52, which improve wear resistance.

Performance and reliability enhancement of linear coolers

NASA Astrophysics Data System (ADS)

Mai, M.; Rühlich, I.; Schreiter, A.; Zehner, S.

2010-04-01

Highest efficiency states a crucial requirement for modern tactical IR cryocooling systems. For enhancement of overall efficiency, AIM cryocooler designs where reassessed considering all relevant loss mechanisms and associated components. Performed investigation was based on state-of-the-art simulation software featuring magnet circuitry analysis as well as computational fluid dynamics (CFD) to realistically replicate thermodynamic interactions. As a result, an improved design for AIM linear coolers could be derived. This paper gives an overview on performance enhancement activities and major results. An additional key-requirement for cryocoolers is reliability. In recent time, AIM has introduced linear coolers with full Flexure Bearing suspension on both ends of the driving mechanism incorporating Moving Magnet piston drive. In conjunction with a Pulse-Tube coldfinger these coolers are capable of meeting MTTF's (Mean Time To Failure) in excess of 50,000 hours offering superior reliability for space applications. Ongoing development also focuses on reliability enhancement, deriving space technology into tactical solutions combining both, excelling specific performance with space like reliability. Concerned publication will summarize the progress of this reliability program and give further prospect.

Wind Power Reliability Research | Wind | NREL

Science.gov Websites

Reliability Collaborative fact sheet. Wind Turbine Blade Reliability Wind turbine blade failures are an extremely rare occurrence, but when they do happen, the results can be catastrophic. For this reason, blade manufacturers require tests of blade properties, static mechanical tests, and fatigue tests to certify wind

Algorithmic mechanisms for reliable crowdsourcing computation under collusion.

PubMed

Fernández Anta, Antonio; Georgiou, Chryssis; Mosteiro, Miguel A; Pareja, Daniel

2015-01-01

We consider a computing system where a master processor assigns a task for execution to worker processors that may collude. We model the workers' decision of whether to comply (compute the task) or not (return a bogus result to save the computation cost) as a game among workers. That is, we assume that workers are rational in a game-theoretic sense. We identify analytically the parameter conditions for a unique Nash Equilibrium where the master obtains the correct result. We also evaluate experimentally mixed equilibria aiming to attain better reliability-profit trade-offs. For a wide range of parameter values that may be used in practice, our simulations show that, in fact, both master and workers are better off using a pure equilibrium where no worker cheats, even under collusion, and even for colluding behaviors that involve deviating from the game.

Algorithmic Mechanisms for Reliable Crowdsourcing Computation under Collusion

PubMed Central

Fernández Anta, Antonio; Georgiou, Chryssis; Mosteiro, Miguel A.; Pareja, Daniel

2015-01-01

We consider a computing system where a master processor assigns a task for execution to worker processors that may collude. We model the workers’ decision of whether to comply (compute the task) or not (return a bogus result to save the computation cost) as a game among workers. That is, we assume that workers are rational in a game-theoretic sense. We identify analytically the parameter conditions for a unique Nash Equilibrium where the master obtains the correct result. We also evaluate experimentally mixed equilibria aiming to attain better reliability-profit trade-offs. For a wide range of parameter values that may be used in practice, our simulations show that, in fact, both master and workers are better off using a pure equilibrium where no worker cheats, even under collusion, and even for colluding behaviors that involve deviating from the game. PMID:25793524

A reliability and mass perspective of SP-100 Stirling cycle lunar-base powerplant designs

NASA Technical Reports Server (NTRS)

Bloomfield, Harvey S.

1991-01-01

The purpose was to obtain reliability and mass perspectives on selection of space power system conceptual designs based on SP-100 reactor and Stirling cycle power-generation subsystems. The approach taken was to: (1) develop a criterion for an acceptable overall reliability risk as a function of the expected range of emerging technology subsystem unit reliabilities; (2) conduct reliability and mass analyses for a diverse matrix of 800-kWe lunar-base design configurations employing single and multiple powerplants with both full and partial subsystem redundancy combinations; and (3) derive reliability and mass perspectives on selection of conceptual design configurations that meet an acceptable reliability criterion with the minimum system mass increase relative to reference powerplant design. The developed perspectives provided valuable insight into the considerations required to identify and characterize high-reliability and low-mass lunar-base powerplant conceptual design.

Software For Computing Reliability Of Other Software

NASA Technical Reports Server (NTRS)

Nikora, Allen; Antczak, Thomas M.; Lyu, Michael

1995-01-01

Computer Aided Software Reliability Estimation (CASRE) computer program developed for use in measuring reliability of other software. Easier for non-specialists in reliability to use than many other currently available programs developed for same purpose. CASRE incorporates mathematical modeling capabilities of public-domain Statistical Modeling and Estimation of Reliability Functions for Software (SMERFS) computer program and runs in Windows software environment. Provides menu-driven command interface; enabling and disabling of menu options guides user through (1) selection of set of failure data, (2) execution of mathematical model, and (3) analysis of results from model. Written in C language.

Benchmarks and Reliable DFT Results for Spin Gaps of Small Ligand Fe(II) Complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Suhwan; Kim, Min-Cheol; Sim, Eunji

2017-05-01

All-electron fixed-node diffusion Monte Carlo provides benchmark spin gaps for four Fe(II) octahedral complexes. Standard quantum chemical methods (semilocal DFT and CCSD(T)) fail badly for the energy difference between their high- and low-spin states. Density-corrected DFT is both significantly more accurate and reliable and yields a consistent prediction for the Fe-Porphyrin complex

78 FR 41339 - Electric Reliability Organization Proposal To Retire Requirements in Reliability Standards

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-10

...] Electric Reliability Organization Proposal To Retire Requirements in Reliability Standards AGENCY: Federal... Reliability Standards identified by the North American Electric Reliability Corporation (NERC), the Commission-certified Electric Reliability Organization. FOR FURTHER INFORMATION CONTACT: Kevin Ryan (Legal Information...

Age-Related Differences in Test-Retest Reliability in Resting-State Brain Functional Connectivity

PubMed Central

Song, Jie; Desphande, Alok S.; Meier, Timothy B.; Tudorascu, Dana L.; Vergun, Svyatoslav; Nair, Veena A.; Biswal, Bharat B.; Meyerand, Mary E.; Birn, Rasmus M.; Bellec, Pierre; Prabhakaran, Vivek

2012-01-01

Resting-state functional MRI (rs-fMRI) has emerged as a powerful tool for investigating brain functional connectivity (FC). Research in recent years has focused on assessing the reliability of FC across younger subjects within and between scan-sessions. Test-retest reliability in resting-state functional connectivity (RSFC) has not yet been examined in older adults. In this study, we investigated age-related differences in reliability and stability of RSFC across scans. In addition, we examined how global signal regression (GSR) affects RSFC reliability and stability. Three separate resting-state scans from 29 younger adults (18–35 yrs) and 26 older adults (55–85 yrs) were obtained from the International Consortium for Brain Mapping (ICBM) dataset made publically available as part of the 1000 Functional Connectomes project www.nitrc.org/projects/fcon_1000. 92 regions of interest (ROIs) with 5 cubic mm radius, derived from the default, cingulo-opercular, fronto-parietal and sensorimotor networks, were previously defined based on a recent study. Mean time series were extracted from each of the 92 ROIs from each scan and three matrices of z-transformed correlation coefficients were created for each subject, which were then used for evaluation of multi-scan reliability and stability. The young group showed higher reliability of RSFC than the old group with GSR (p-value = 0.028) and without GSR (p-value <0.001). Both groups showed a high degree of multi-scan stability of RSFC and no significant differences were found between groups. By comparing the test-retest reliability of RSFC with and without GSR across scans, we found significantly higher proportion of reliable connections in both groups without GSR, but decreased stability. Our results suggest that aging is associated with reduced reliability of RSFC which itself is highly stable within-subject across scans for both groups, and that GSR reduces the overall reliability but increases the stability in both

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-19

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

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

PubMed Central

Maier, Andrea B.; Aarts, Ronald G. K. M.; van Gerven, Joop M. A.; Arendzen, J. Hans; Schouten, Alfred C.; Meskers, Carel G. M.; van der Kooij, Herman

2016-01-01

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

RELAV - RELIABILITY/AVAILABILITY ANALYSIS PROGRAM

NASA Technical Reports Server (NTRS)

Bowerman, P. N.

1994-01-01

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

Reliability of Use, Abuse, and Dependence of Four Types of Inhalants in Adolescents and Young Adults

PubMed Central

Ridenour, Ty A.; Bray, Bethany C.; Cottler, Linda B.

2007-01-01

Inhalants, as a class of drugs, consists of heterogeneous substances that include some of the most dangerous drugs on a per use basis. Research on inhalant abuse has lagged behind other drugs partly because of the need for a diagnostic instrument of different types of inhalants. This study was conducted to obtain reliability estimates for the new Substance Abuse Module DSM-IV inhalants diagnoses for four types of inhalants: aerosols, gases, nitrites, and solvents as well as different diagnostic configurations of inhalant use. Participants were 162 community sample adolescents or young adults (mean age = 20.3 years, SD = 2.4). Two-thirds of the sample was male and 83.3% was Caucasian. Kappas and intraclass correlation coefficients were computed to estimate test-retest reliabilities. Results suggested (a) abuse was more common than dependence (34.6% vs. 12.3%), (b) reliabilities of abuse criteria and diagnosis were good to excellent across subtypes, and (c) reliabilities of dependence criteria and diagnoses were poor to good across subtypes. Alternative configurations of DSM-IV criteria that were consistent with previous research on adolescents provided excellent reliabilities across subtypes of inhalants. Moreover, 11.1% of participants experienced inhalants withdrawal. PMID:17576041

Optimization of Adaptive Intraply Hybrid Fiber Composites with Reliability Considerations

NASA Technical Reports Server (NTRS)

Shiao, Michael C.; Chamis, Christos C.

1994-01-01

The reliability with bounded distribution parameters (mean, standard deviation) was maximized and the reliability-based cost was minimized for adaptive intra-ply hybrid fiber composites by using a probabilistic method. The probabilistic method accounts for all naturally occurring uncertainties including those in constituent material properties, fabrication variables, structure geometry, and control-related parameters. Probabilistic sensitivity factors were computed and used in the optimization procedures. For actuated change in the angle of attack of an airfoil-like composite shell structure with an adaptive torque plate, the reliability was maximized to 0.9999 probability, with constraints on the mean and standard deviation of the actuation material volume ratio (percentage of actuation composite material in a ply) and the actuation strain coefficient. The reliability-based cost was minimized for an airfoil-like composite shell structure with an adaptive skin and a mean actuation material volume ratio as the design parameter. At a O.9-mean actuation material volume ratio, the minimum cost was obtained.

Reliability of emerging bonded interface materials for large-area attachments

DOE PAGES

Paret, Paul P.; DeVoto, Douglas J.; Narumanchi, Sreekant

2015-12-30

In this study, conventional thermal interface materials (TIMs), such as greases, gels, and phase change materials, pose bottlenecks to heat removal and have long caused reliability issues in automotive power electronics packages. Bonded interface materials (BIMs) with superior thermal performance have the potential to be a replacement to the conventional TIMs. However, due to coefficient of thermal expansion mismatches between different components in a package and resultant thermomechanical stresses, fractures or delamination could occur, causing serious reliability concerns. These defects manifest themselves in increased thermal resistance in the package. In this paper, the results of reliability evaluation of emerging BIMsmore » for large-area attachments in power electronics packaging are reported. Thermoplastic (polyamide) adhesive with embedded near-vertical-aligned carbon fibers, sintered silver, and conventional lead solder (Sn 63Pb 37) materials were bonded between 50.8 mm x 50.8 mm cross-sectional footprint silicon nitride substrates and copper base plate samples, and were subjected to accelerated thermal cycling until failure or 2500 cycles. Damage in the BIMs was monitored every 100 cycles by scanning acoustic microscopy. Thermoplastic with embedded carbon fibers performed the best with no defects, whereas sintered silver and lead solder failed at 2300 and 1400 thermal cycles, respectively. Besides thermal cycling, additional lead solder samples were subjected to thermal shock and thermal cycling with extended dwell periods. A finite element method (FEM)-based model was developed to simulate the behavior of lead solder under thermomechanical loading. Strain energy density per cycle results were calculated from the FEM simulations. A predictive lifetime model was formulated for lead solder by correlating strain energy density results extracted from modeling with cycles-to-failure obtained from experimental accelerated tests. A power-law-based approach

Inter-rater reliability and aspects of validity of the parent-infant relationship global assessment scale (PIR-GAS)

PubMed Central

2013-01-01

Background The Parent-Infant Relationship Global Assessment Scale (PIR-GAS) signifies a conceptually relevant development in the multi-axial, developmentally sensitive classification system DC:0-3R for preschool children. However, information about the reliability and validity of the PIR-GAS is rare. A review of the available empirical studies suggests that in research, PIR-GAS ratings can be based on a ten-minute videotaped interaction sequence. The qualification of raters may be very heterogeneous across studies. Methods To test whether the use of the PIR-GAS still allows for a reliable assessment of the parent-infant relationship, our study compared a PIR-GAS ratings based on a full-information procedure across multiple settings with ratings based on a ten-minute video by two doctoral candidates of medicine. For each mother-child dyad at a family day hospital (N = 48), we obtained two video ratings and one full-information rating at admission to therapy and at discharge. This pre-post design allowed for a replication of our findings across the two measurement points. We focused on the inter-rater reliability between the video coders, as well as between the video and full-information procedure, including mean differences and correlations between the raters. Additionally, we examined aspects of the validity of video and full-information ratings based on their correlation with measures of child and maternal psychopathology. Results Our results showed that a ten-minute video and full-information PIR-GAS ratings were not interchangeable. Most results at admission could be replicated by the data obtained at discharge. We concluded that a higher degree of standardization of the assessment procedure should increase the reliability of the PIR-GAS, and a more thorough theoretical foundation of the manual should increase its validity. PMID:23705962

Ultrasound measures of supraspinatus tendon thickness and acromiohumeral distance in rotator cuff tendinopathy are reliable.

PubMed

McCreesh, Karen M; Anjum, Shakeel; Crotty, James M; Lewis, Jeremy S

2016-01-01

Rotator cuff (RC) tendinopathy has been widely ascribed to impingement of the supraspinatus tendon (SsT) in the subacromial space, measured as the acromiohumeral distance (AHD). Ultrasound (US) is suitable for measuring AHD and SsT thickness, but few reliability studies have been carried out in symptomatic populations, and interrater reliability is unconfirmed. This study aimed to examine the intrarater and interrater reliability of US measurements of AHD and SsT thickness in asymptomatic control subjects and patients with RC tendinopathy. Seventy participants were recruited and grouped as healthy controls (n = 25) and RC tendinopathy (n = 45). Repeated US measurements of AHD and SsT thickness were obtained by one rater in both groups and by two raters in the RC tendinopathy group. Intrarater and interrater reliability coefficients were excellent for both measurements (intraclass correlation > 0.92), but the intrarater reliability was superior. The minimal detectable change values in the symptomatic group were 0.7 mm for AHD and 0.6 mm for SsT thickness for a single experienced examiner; the values rose to 1.2 mm and 1.3 mm, respectively, for the pair of examiners. The results support the reliability of US for the measurement of AHD and SsT thickness in patients with symptomatic RC tendinopathy and provide minimal detectable change values for use in future research studies. © 2015 Wiley Periodicals, Inc.

Comprehensive Design Reliability Activities for Aerospace Propulsion Systems

NASA Technical Reports Server (NTRS)

Christenson, R. L.; Whitley, M. R.; Knight, K. C.

2000-01-01

This technical publication describes the methodology, model, software tool, input data, and analysis result that support aerospace design reliability studies. The focus of these activities is on propulsion systems mechanical design reliability. The goal of these activities is to support design from a reliability perspective. Paralleling performance analyses in schedule and method, this requires the proper use of metrics in a validated reliability model useful for design, sensitivity, and trade studies. Design reliability analysis in this view is one of several critical design functions. A design reliability method is detailed and two example analyses are provided-one qualitative and the other quantitative. The use of aerospace and commercial data sources for quantification is discussed and sources listed. A tool that was developed to support both types of analyses is presented. Finally, special topics discussed include the development of design criteria, issues of reliability quantification, quality control, and reliability verification.

Sample size planning for composite reliability coefficients: accuracy in parameter estimation via narrow confidence intervals.

PubMed

Terry, Leann; Kelley, Ken

2012-11-01

Composite measures play an important role in psychology and related disciplines. Composite measures almost always have error. Correspondingly, it is important to understand the reliability of the scores from any particular composite measure. However, the point estimates of the reliability of composite measures are fallible and thus all such point estimates should be accompanied by a confidence interval. When confidence intervals are wide, there is much uncertainty in the population value of the reliability coefficient. Given the importance of reporting confidence intervals for estimates of reliability, coupled with the undesirability of wide confidence intervals, we develop methods that allow researchers to plan sample size in order to obtain narrow confidence intervals for population reliability coefficients. We first discuss composite reliability coefficients and then provide a discussion on confidence interval formation for the corresponding population value. Using the accuracy in parameter estimation approach, we develop two methods to obtain accurate estimates of reliability by planning sample size. The first method provides a way to plan sample size so that the expected confidence interval width for the population reliability coefficient is sufficiently narrow. The second method ensures that the confidence interval width will be sufficiently narrow with some desired degree of assurance (e.g., 99% assurance that the 95% confidence interval for the population reliability coefficient will be less than W units wide). The effectiveness of our methods was verified with Monte Carlo simulation studies. We demonstrate how to easily implement the methods with easy-to-use and freely available software. ©2011 The British Psychological Society.

Probabilistic fatigue methodology for six nines reliability

NASA Technical Reports Server (NTRS)

Everett, R. A., Jr.; Bartlett, F. D., Jr.; Elber, Wolf

1990-01-01

Fleet readiness and flight safety strongly depend on the degree of reliability that can be designed into rotorcraft flight critical components. The current U.S. Army fatigue life specification for new rotorcraft is the so-called six nines reliability, or a probability of failure of one in a million. The progress of a round robin which was established by the American Helicopter Society (AHS) Subcommittee for Fatigue and Damage Tolerance is reviewed to investigate reliability-based fatigue methodology. The participants in this cooperative effort are in the U.S. Army Aviation Systems Command (AVSCOM) and the rotorcraft industry. One phase of the joint activity examined fatigue reliability under uniquely defined conditions for which only one answer was correct. The other phases were set up to learn how the different industry methods in defining fatigue strength affected the mean fatigue life and reliability calculations. Hence, constant amplitude and spectrum fatigue test data were provided so that each participant could perform their standard fatigue life analysis. As a result of this round robin, the probabilistic logic which includes both fatigue strength and spectrum loading variability in developing a consistant reliability analysis was established. In this first study, the reliability analysis was limited to the linear cumulative damage approach. However, it is expected that superior fatigue life prediction methods will ultimately be developed through this open AHS forum. To that end, these preliminary results were useful in identifying some topics for additional study.

Comparison of the dose distribution obtained from dosimetric systems with intensity modulated radiotherapy planning system in the treatment of prostate cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gökçe, M., E-mail: mgokce@adu.edu.tr; Uslu, D. Koçyiğit; Ertunç, C.

The aim of this study is to compare Intensity Modulated Radiation Therapy (IMRT) plan of prostate cancer patients with different dose verification systems in dosimetric aspects and to compare these systems with each other in terms of reliability, applicability and application time. Dosimetric control processes of IMRT plan of three prostate cancer patients were carried out using thermoluminescent dosimeter (TLD), ion chamber (IC) and 2D Array detector systems. The difference between the dose values obtained from the dosimetric systems and treatment planning system (TPS) were found to be about % 5. For the measured (TLD) and calculated (TPS) doses %3more » percentage differences were obtained for the points close to center while percentage differences increased at the field edges. It was found that TLD and IC measurements will increase the precision and reliability of the results of 2D Array.« less

Visual judgements of steadiness in one-legged stance: reliability and validity.

PubMed

Haupstein, T; Goldie, P

2000-01-01

There is a paucity of information about the validity and reliability of clinicians' visual judgements of steadiness in one-legged stance. Such judgements are used frequently in clinical practice to support decisions about treatment in the fields of neurology, sports medicine, paediatrics and orthopaedics. The aim of the present study was to address the validity and reliability of visual judgements of steadiness in one-legged stance in a group of physiotherapists. A videotape of 20 five-second performances was shown to 14 physiotherapists with median clinical experience of 6.75 years. Validity of visual judgement was established by correlating scores obtained from an 11-point rating scale with criterion scores obtained from a force platform. In addition, partial correlations were used to control for the potential influence of body weight on the relationship between the visual judgements and criterion scores. Inter-observer reliability was quantified between the physiotherapists; intra-observer reliability was quantified between two tests four weeks apart. Mean criterion-related validity was high, regardless of whether body weight was controlled for statistically (Pearson's r = 0.84, 0.83, respectively). The standard error of estimating the criterion score was 3.3 newtons. Inter-observer reliability was high (ICC (2,1) = 0.81 at Test 1 and 0.82 at Test 2). Intra-observer reliability was high (on average ICC (2,1) = 0.88; Pearson's r = 0.90). The standard error of measurement for the 11-point scale was one unit. The finding of higher accuracy of making visual judgements than previously reported may be due to several aspects of design: use of a criterion score derived from the variability of the force signal which is more discriminating than variability of centre of pressure; use of a discriminating visual rating scale; specificity and clear definition of the phenomenon to be rated.

New high-definition thickness data obtained at tropical glaciers: preliminary results from Antisana volcano (Ecuador) using GPR prospection

NASA Astrophysics Data System (ADS)

Zapata, Camilo; Andrade, Daniel; Córdova, Jorge; Maisincho, Luis; Carvajal, Juan; Calispa, Marlon; Villacís, Marcos

2014-05-01

The study of tropical glaciers has been a significant contribution to the understanding of glacier dynamics and climate change. Much of the data and results have been obtained by analyzing plan-view images obtained by air- and space-borne sensors, as well as depth data obtained by diverse methodologies at selected points on the glacier surface. However, the measurement of glacier thicknesses has remained an elusive task in tropical glaciers, often located in rough terrains where the application of geophysical surveys (i.e. seismic surveys) requires logistics sometimes hardly justified by the amount of obtained data. In the case of Ecuador, however, where most glaciers have developed on active volcanoes and represent sources/reservoirs of fresh water, the precise knowledge of such information is fundamental for scientific research but also in order to better assess key aspects for the society. The relatively recent but fast development of the GPR technology has helped to obtain new highdefinition thickness data at Antisana volcano that will be used to: 1) better understand the dynamics and fate of tropical glaciers; 2) better estimate the amount of fresh water stored in the glaciers; 3) better assess the hazards associated with the sudden widespread melting of glaciers during volcanic eruptions. The measurements have been obtained at glaciers 12 and 15 of Antisana volcano, with the help of a commercial GPR equipped with a 25 MHz antenna. A total of 30 transects have been obtained, covering a distance of more than 3 km, from the glacier ablation zone, located at ~ 4600 masl, up to the level of 5200 masl. The preliminary results show a positive correlation between altitude and glacier thickness, with maximum and minimum calculated values reaching up to 80 m, and down to 15 m, respectively. The experience gained at Antisana volcano will be used to prepare a more widespread GPR survey in the glaciers of Cotopaxi volcano, whose implications in terms of volcanic hazards

Modeling reliability measurement of interface on information system: Towards the forensic of rules

NASA Astrophysics Data System (ADS)

Nasution, M. K. M.; Sitompul, Darwin; Harahap, Marwan

2018-02-01

Today almost all machines depend on the software. As a software and hardware system depends also on the rules that are the procedures for its use. If the procedure or program can be reliably characterized by involving the concept of graph, logic, and probability, then regulatory strength can also be measured accordingly. Therefore, this paper initiates an enumeration model to measure the reliability of interfaces based on the case of information systems supported by the rules of use by the relevant agencies. An enumeration model is obtained based on software reliability calculation.

Reliability Generalization of the Alcohol Use Disorder Identification Test.

ERIC Educational Resources Information Center

Shields, Alan L.; Caruso, John C.

2002-01-01

Evaluated the reliability of scores from the Alcohol Use Disorders Identification Test (AUDIT; J. Sounders and others, 1993) in a reliability generalization study based on 17 empirical journal articles. Results show AUDIT scores to be generally reliable for basic assessment. (SLD)

Reliability analysis of the objective structured clinical examination using generalizability theory.

PubMed

Trejo-Mejía, Juan Andrés; Sánchez-Mendiola, Melchor; Méndez-Ramírez, Ignacio; Martínez-González, Adrián

2016-01-01

Background The objective structured clinical examination (OSCE) is a widely used method for assessing clinical competence in health sciences education. Studies using this method have shown evidence of validity and reliability. There are no published studies of OSCE reliability measurement with generalizability theory (G-theory) in Latin America. The aims of this study were to assess the reliability of an OSCE in medical students using G-theory and explore its usefulness for quality improvement. Methods An observational cross-sectional study was conducted at National Autonomous University of Mexico (UNAM) Faculty of Medicine in Mexico City. A total of 278 fifth-year medical students were assessed with an 18-station OSCE in a summative end-of-career final examination. There were four exam versions. G-theory with a crossover random effects design was used to identify the main sources of variance. Examiners, standardized patients, and cases were considered as a single facet of analysis. Results The exam was applied to 278 medical students. The OSCE had a generalizability coefficient of 0.93. The major components of variance were stations, students, and residual error. The sites and the versions of the tests had minimum variance. Conclusions Our study achieved a G coefficient similar to that found in other reports, which is acceptable for summative tests. G-theory allows the estimation of the magnitude of multiple sources of error and helps decision makers to determine the number of stations, test versions, and examiners needed to obtain reliable measurements.

Metrological Reliability of Medical Devices

NASA Astrophysics Data System (ADS)

Costa Monteiro, E.; Leon, L. F.

2015-02-01

The prominent development of health technologies of the 20th century triggered demands for metrological reliability of physiological measurements comprising physical, chemical and biological quantities, essential to ensure accurate and comparable results of clinical measurements. In the present work, aspects concerning metrological reliability in premarket and postmarket assessments of medical devices are discussed, pointing out challenges to be overcome. In addition, considering the social relevance of the biomeasurements results, Biometrological Principles to be pursued by research and innovation aimed at biomedical applications are proposed, along with the analysis of their contributions to guarantee the innovative health technologies compliance with the main ethical pillars of Bioethics.

A Time-Variant Reliability Model for Copper Bending Pipe under Seawater-Active Corrosion Based on the Stochastic Degradation Process

PubMed Central

Li, Mengmeng; Feng, Qiang; Yang, Dezhen

2018-01-01

In the degradation process, the randomness and multiplicity of variables are difficult to describe by mathematical models. However, they are common in engineering and cannot be neglected, so it is necessary to study this issue in depth. In this paper, the copper bending pipe in seawater piping systems is taken as the analysis object, and the time-variant reliability is calculated by solving the interference of limit strength and maximum stress. We did degradation experiments and tensile experiments on copper material, and obtained the limit strength at each time. In addition, degradation experiments on copper bending pipe were done and the thickness at each time has been obtained, then the response of maximum stress was calculated by simulation. Further, with the help of one kind of Monte Carlo method we propose, the time-variant reliability of copper bending pipe was calculated based on the stochastic degradation process and interference theory. Compared with traditional methods and verified by maintenance records, the results show that the time-variant reliability model based on the stochastic degradation process proposed in this paper has better applicability in the reliability analysis, and it can be more convenient and accurate to predict the replacement cycle of copper bending pipe under seawater-active corrosion. PMID:29584695

Reliability and risk assessment of structures

NASA Technical Reports Server (NTRS)

Chamis, C. C.

1991-01-01

Development of reliability and risk assessment of structural components and structures is a major activity at Lewis Research Center. It consists of five program elements: (1) probabilistic loads; (2) probabilistic finite element analysis; (3) probabilistic material behavior; (4) assessment of reliability and risk; and (5) probabilistic structural performance evaluation. Recent progress includes: (1) the evaluation of the various uncertainties in terms of cumulative distribution functions for various structural response variables based on known or assumed uncertainties in primitive structural variables; (2) evaluation of the failure probability; (3) reliability and risk-cost assessment; and (4) an outline of an emerging approach for eventual certification of man-rated structures by computational methods. Collectively, the results demonstrate that the structural durability/reliability of man-rated structural components and structures can be effectively evaluated by using formal probabilistic methods.

Reliability of MEG source imaging of anterior temporal spikes: analysis of an intracranially characterized spike focus.

PubMed

Wennberg, Richard; Cheyne, Douglas

2014-05-01

To assess the reliability of MEG source imaging (MSI) of anterior temporal spikes through detailed analysis of the localization and orientation of source solutions obtained for a large number of spikes that were separately confirmed by intracranial EEG to be focally generated within a single, well-characterized spike focus. MSI was performed on 64 identical right anterior temporal spikes from an anterolateral temporal neocortical spike focus. The effects of different volume conductors (sphere and realistic head model), removal of noise with low frequency filters (LFFs) and averaging multiple spikes were assessed in terms of the reliability of the source solutions. MSI of single spikes resulted in scattered dipole source solutions that showed reasonable reliability for localization at the lobar level, but only for solutions with a goodness-of-fit exceeding 80% using a LFF of 3 Hz. Reliability at a finer level of intralobar localization was limited. Spike averaging significantly improved the reliability of source solutions and averaging 8 or more spikes reduced dependency on goodness-of-fit and data filtering. MSI performed on topographically identical individual spikes from an intracranially defined classical anterior temporal lobe spike focus was limited by low reliability (i.e., scattered source solutions) in terms of fine, sublobar localization within the ipsilateral temporal lobe. Spike averaging significantly improved reliability. MSI performed on individual anterior temporal spikes is limited by low reliability. Reduction of background noise through spike averaging significantly improves the reliability of MSI solutions. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Mission Reliability Estimation for Repairable Robot Teams

NASA Technical Reports Server (NTRS)

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

Atomistic mechanisms of ReRAM cell operation and reliability

NASA Astrophysics Data System (ADS)

Pandey, Sumeet C.

2018-01-01

We present results from first-principles-based modeling that captures functionally important physical phenomena critical to cell materials selection, operation, and reliability for resistance-switching memory technologies. An atomic-scale description of retention, the low- and high-resistance states (RS), and the sources of intrinsic cell-level variability in ReRAM is discussed. Through the results obtained from density functional theory, non-equilibrium Green’s function, molecular dynamics, and kinetic Monte Carlo simulations; the role of variable-charge vacancy defects and metal impurities in determining the RS, the LRS-stability, and electron-conduction in such RS is reported. Although, the statistical electrical characteristics of the oxygen-vacancy (Ox-ReRAM) and conductive-bridging RAM (M-ReRAM) are notably different, the underlying similar electrochemical phenomena describing retention and formation/dissolution of RS are being discussed.

Regional Reliability of Quantitative Signal Targeting with Alternating Radiofrequency (STAR) Labeling of Arterial Regions (QUASAR)

PubMed Central

Tatewaki, Yasuko; Higano, Shuichi; Taki, Yasuyuki; Thyreau, Benjamin; Murata, Takaki; Mugikura, Shunji; Ito, Daisuke; Takase, Kei; Takahashi, Shoki

2014-01-01

BACKGROUND AND PURPOSE Quantitative signal targeting with alternating radiofrequency labeling of arterial regions (QUASAR) is a recent spin labeling technique that could improve the reliability of brain perfusion measurements. Although it is considered reliable for measuring gray matter as a whole, it has never been evaluated regionally. Here we assessed this regional reliability. METHODS Using a 3-Tesla Philips Achieva whole-body system, we scanned four times 10 healthy volunteers, in two sessions 2 weeks apart, to obtain QUASAR images. We computed perfusion images and ran a voxel-based analysis within all brain structures. We also calculated mean regional cerebral blood flow (rCBF) within regions of interest configured for each arterial territory distribution. RESULTS The mean CBF over whole gray matter was 37.74 with intraclass correlation coefficient (ICC) of .70. In white matter, it was 13.94 with an ICC of .30. Voxel-wise ICC and coefficient-of-variation maps showed relatively lower reliability in watershed areas and white matter especially in deeper white matter. The absolute mean rCBF values were consistent with the ones reported from PET, as was the relatively low variability in different feeding arteries. CONCLUSIONS Thus, QUASAR reliability for regional perfusion is high within gray matter, but uncertain within white matter. PMID:25370338

Tactile Acuity Charts: A Reliable Measure of Spatial Acuity

PubMed Central

Bruns, Patrick; Camargo, Carlos J.; Campanella, Humberto; Esteve, Jaume; Dinse, Hubert R.; Röder, Brigitte

2014-01-01

For assessing tactile spatial resolution it has recently been recommended to use tactile acuity charts which follow the design principles of the Snellen letter charts for visual acuity and involve active touch. However, it is currently unknown whether acuity thresholds obtained with this newly developed psychophysical procedure are in accordance with established measures of tactile acuity that involve passive contact with fixed duration and control of contact force. Here we directly compared tactile acuity thresholds obtained with the acuity charts to traditional two-point and grating orientation thresholds in a group of young healthy adults. For this purpose, two types of charts, using either Braille-like dot patterns or embossed Landolt rings with different orientations, were adapted from previous studies. Measurements with the two types of charts were equivalent, but generally more reliable with the dot pattern chart. A comparison with the two-point and grating orientation task data showed that the test-retest reliability of the acuity chart measurements after one week was superior to that of the passive methods. Individual thresholds obtained with the acuity charts agreed reasonably with the grating orientation threshold, but less so with the two-point threshold that yielded relatively distinct acuity estimates compared to the other methods. This potentially considerable amount of mismatch between different measures of tactile acuity suggests that tactile spatial resolution is a complex entity that should ideally be measured with different methods in parallel. The simple test procedure and high reliability of the acuity charts makes them a promising complement and alternative to the traditional two-point and grating orientation thresholds. PMID:24504346

Reliability training

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Reliability culture at La Silla Paranal Observatory

NASA Astrophysics Data System (ADS)

Gonzalez, Sergio

2010-07-01

The Maintenance Department at the La Silla - Paranal Observatory has been an important base to keep the operations of the observatory at a good level of reliability and availability. Several strategies have been implemented and improved in order to cover these requirements and keep the system and equipment working properly when it is required. For that reason, one of the latest improvements has been the introduction of the concept of reliability, which implies that we don't simply speak about reliability concepts. It involves much more than that. It involves the use of technologies, data collecting, data analysis, decision making, committees concentrated in analysis of failure modes and how they can be eliminated, aligning the results with the requirements of our internal partners and establishing steps to achieve success. Some of these steps have already been implemented: data collection, use of technologies, analysis of data, development of priority tools, committees dedicated to analyze data and people dedicated to reliability analysis. This has permitted us to optimize our process, analyze where we can improve, avoid functional failures, reduce the failures range in several systems and subsystems; all this has had a positive impact in terms of results for our Observatory. All these tools are part of the reliability culture that allows our system to operate with a high level of reliability and availability.

Reliability as Argument

ERIC Educational Resources Information Center

Parkes, Jay

2007-01-01

Reliability consists of both important social and scientific values and methods for evidencing those values, though in practice methods are often conflated with the values. With the two distinctly understood, a reliability argument can be made that articulates the particular reliability values most relevant to the particular measurement situation…

Sarma-based key-group method for rock slope reliability analyses

NASA Astrophysics Data System (ADS)

Yarahmadi Bafghi, A. R.; Verdel, T.

2005-08-01

The methods used in conducting static stability analyses have remained pertinent to this day for reasons of both simplicity and speed of execution. The most well-known of these methods for purposes of stability analysis of fractured rock masses is the key-block method (KBM).This paper proposes an extension to the KBM, called the key-group method (KGM), which combines not only individual key-blocks but also groups of collapsable blocks into an iterative and progressive analysis of the stability of discontinuous rock slopes. To take intra-group forces into account, the Sarma method has been implemented within the KGM in order to generate a Sarma-based KGM, abbreviated SKGM. We will discuss herein the hypothesis behind this new method, details regarding its implementation, and validation through comparison with results obtained from the distinct element method.Furthermore, as an alternative to deterministic methods, reliability analyses or probabilistic analyses have been proposed to take account of the uncertainty in analytical parameters and models. The FOSM and ASM probabilistic methods could be implemented within the KGM and SKGM framework in order to take account of the uncertainty due to physical and mechanical data (density, cohesion and angle of friction). We will then show how such reliability analyses can be introduced into SKGM to give rise to the probabilistic SKGM (PSKGM) and how it can be used for rock slope reliability analyses. Copyright

Estimating the Reliability of Single-Item Life Satisfaction Measures: Results from Four National Panel Studies

ERIC Educational Resources Information Center

Lucas, Richard E.; Donnellan, M. Brent

2012-01-01

Life satisfaction is often assessed using single-item measures. However, estimating the reliability of these measures can be difficult because internal consistency coefficients cannot be calculated. Existing approaches use longitudinal data to isolate occasion-specific variance from variance that is either completely stable or variance that…

Geodetic results from ISAGEX data. [for obtaining center of mass coordinates for geodetic camera sites

NASA Technical Reports Server (NTRS)

Marsh, J. G.; Douglas, B. C.; Walls, D. M.

1974-01-01

Laser and camera data taken during the International Satellite Geodesy Experiment (ISAGEX) were used in dynamical solutions to obtain center-of-mass coordinates for the Astro-Soviet camera sites at Helwan, Egypt, and Oulan Bator, Mongolia, as well as the East European camera sites at Potsdam, German Democratic Republic, and Ondrejov, Czechoslovakia. The results are accurate to about 20m in each coordinate. The orbit of PEOLE (i=15) was also determined from ISAGEX data. Mean Kepler elements suitable for geodynamic investigations are presented.

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

NASA Astrophysics Data System (ADS)

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.

Photovoltaic performance and reliability workshop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroposki, B

1996-10-01

This proceedings is the compilation of papers presented at the ninth PV Performance and Reliability Workshop held at the Sheraton Denver West Hotel on September 4--6, 1996. This years workshop included presentations from 25 speakers and had over 100 attendees. All of the presentations that were given are included in this proceedings. Topics of the papers included: defining service lifetime and developing models for PV module lifetime; examining and determining failure and degradation mechanisms in PV modules; combining IEEE/IEC/UL testing procedures; AC module performance and reliability testing; inverter reliability/qualification testing; standardization of utility interconnect requirements for PV systems; need activitiesmore » to separate variables by testing individual components of PV systems (e.g. cells, modules, batteries, inverters,charge controllers) for individual reliability and then test them in actual system configurations; more results reported from field experience on modules, inverters, batteries, and charge controllers from field deployed PV systems; and system certification and standardized testing for stand-alone and grid-tied systems.« less

Culture Representation in Human Reliability Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

David Gertman; Julie Marble; Steven Novack

Understanding human-system response is critical to being able to plan and predict mission success in the modern battlespace. Commonly, human reliability analysis has been used to predict failures of human performance in complex, critical systems. However, most human reliability methods fail to take culture into account. This paper takes an easily understood state of the art human reliability analysis method and extends that method to account for the influence of culture, including acceptance of new technology, upon performance. The cultural parameters used to modify the human reliability analysis were determined from two standard industry approaches to cultural assessment: Hofstede’s (1991)more » 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.« less

Design for reliability: NASA reliability preferred practices for design and test

NASA Technical Reports Server (NTRS)

Lalli, Vincent R.

1994-01-01

This tutorial summarizes reliability experience from both NASA and industry and reflects engineering practices that support current and future civil space programs. These practices were collected from various NASA field centers and were reviewed by a committee of senior technical representatives from the participating centers (members are listed at the end). The material for this tutorial was taken from the publication issued by the NASA Reliability and Maintainability Steering Committee (NASA Reliability Preferred Practices for Design and Test. NASA TM-4322, 1991). Reliability must be an integral part of the systems engineering process. Although both disciplines must be weighed equally with other technical and programmatic demands, the application of sound reliability principles will be the key to the effectiveness and affordability of America's space program. Our space programs have shown that reliability efforts must focus on the design characteristics that affect the frequency of failure. Herein, we emphasize that these identified design characteristics must be controlled by applying conservative engineering principles.

Software reliability experiments data analysis and investigation

NASA Technical Reports Server (NTRS)

Walker, J. Leslie; Caglayan, Alper K.

1991-01-01

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

A Pilot Study Examining the Test-Retest and Internal Consistency Reliability of the ABLLS-R

ERIC Educational Resources Information Center

Partington, James W.; Bailey, Autumn; Partington, Scott W.

2018-01-01

The literature contains a variety of assessment tools for measuring the skills of individuals with autism or other developmental delays, but most lack adequate empirical evidence supporting their reliability and validity. The current pilot study sought to examine the reliability of scores obtained from the Assessment of Basic Language and Learning…

Coefficient Alpha and Reliability of Scale Scores

ERIC Educational Resources Information Center

Almehrizi, Rashid S.

2013-01-01

The majority of large-scale assessments develop various score scales that are either linear or nonlinear transformations of raw scores for better interpretations and uses of assessment results. The current formula for coefficient alpha (a; the commonly used reliability coefficient) only provides internal consistency reliability estimates of raw…

Measurement and computer simulation of antennas on ships and aircraft for results of operational reliability

NASA Astrophysics Data System (ADS)

Kubina, Stanley J.

1989-09-01

The review of the status of computational electromagnetics by Miller and the exposition by Burke of the developments in one of the more important computer codes in the application of the electric field integral equation method, the Numerical Electromagnetic Code (NEC), coupled with Molinet's summary of progress in techniques based on the Geometrical Theory of Diffraction (GTD), provide a clear perspective on the maturity of the modern discipline of computational electromagnetics and its potential. Audone's exposition of the application to the computation of Radar Scattering Cross-section (RCS) is an indication of the breadth of practical applications and his exploitation of modern near-field measurement techniques reminds one of progress in the measurement discipline which is essential to the validation or calibration of computational modeling methodology when applied to complex structures such as aircraft and ships. The latter monograph also presents some comparison results with computational models. Some of the results presented for scale model and flight measurements show some serious disagreements in the lobe structure which would require some detailed examination. This also applies to the radiation patterns obtained by flight measurement compared with those obtained using wire-grid models and integral equation modeling methods. In the examples which follow, an attempt is made to match measurements results completely over the entire 2 to 30 MHz HF range for antennas on a large patrol aircraft. The problem of validating computer models of HF antennas on a helicopter and using computer models to generate radiation pattern information which cannot be obtained by measurements are discussed. The use of NEC computer models to analyze top-side ship configurations where measurement results are not available and only self-validation measures are available or at best comparisons with an alternate GTD computer modeling technique is also discussed.

Reliability evaluation methodology for NASA applications

NASA Technical Reports Server (NTRS)

Taneja, Vidya S.

1992-01-01

Liquid rocket engine technology has been characterized by the development of complex systems containing large number of subsystems, components, and parts. The trend to even larger and more complex system is continuing. The liquid rocket engineers have been focusing mainly on performance driven designs to increase payload delivery of a launch vehicle for a given mission. In otherwords, although the failure of a single inexpensive part or component may cause the failure of the system, reliability in general has not been considered as one of the system parameters like cost or performance. Up till now, quantification of reliability has not been a consideration during system design and development in the liquid rocket industry. Engineers and managers have long been aware of the fact that the reliability of the system increases during development, but no serious attempts have been made to quantify reliability. As a result, a method to quantify reliability during design and development is needed. This includes application of probabilistic models which utilize both engineering analysis and test data. Classical methods require the use of operating data for reliability demonstration. In contrast, the method described in this paper is based on similarity, analysis, and testing combined with Bayesian statistical analysis.

Validity and reliability of the Malay version of sleep apnea quality of life index – preliminary results

PubMed Central

2013-01-01

Background The objective of this study was to determine the validity and reliability of the Malay translated Sleep Apnea Quality of Life Index (SAQLI) in patients with obstructive sleep apnea (OSA). Methods In this cross sectional study, the Malay version of SAQLI was administered to 82 OSA patients seen at the OSA Clinic, Hospital Universiti Sains Malaysia prior to their treatment. Additionally, the patients were asked to complete the Malay version of Medical Outcomes Study Short Form (SF-36). Twenty-three patients completed the Malay version of SAQLI again after 1–2 weeks to assess its reliability. Results Initial factor analysis of the 40-item Malay version of SAQLI resulted in four factors with eigenvalues >1. All items had factor loadings >0.5 but one of the factors was unstable with only two items. However, both items were maintained due to their high communalities and the analysis was repeated with a forced three factor solution. Variance accounted by the three factors was 78.17% with 9–18 items per factor. All items had primary loadings over 0.5 although the loadings were inconsistent with the proposed construct. The Cronbach’s alpha values were very high for all domains, >0.90. The instrument was able to discriminate between patients with mild or moderate and severe OSA. The Malay version of SAQLI correlated positively with the SF-36. The intraclass correlation coefficients for all domains were >0.90. Conclusions In light of these preliminary observations, we concluded that the Malay version of SAQLI has a high degree of internal consistency and concurrent validity albeit demonstrating a slightly different construct than the original version. The responsiveness of the questionnaire to changes in health-related quality of life following OSA treatment is yet to be determined. PMID:23786866

A hybrid Jaya algorithm for reliability-redundancy allocation problems

NASA Astrophysics Data System (ADS)

Ghavidel, Sahand; Azizivahed, Ali; Li, Li

2018-04-01

This article proposes an efficient improved hybrid Jaya algorithm based on time-varying acceleration coefficients (TVACs) and the learning phase introduced in teaching-learning-based optimization (TLBO), named the LJaya-TVAC algorithm, for solving various types of nonlinear mixed-integer reliability-redundancy allocation problems (RRAPs) and standard real-parameter test functions. RRAPs include series, series-parallel, complex (bridge) and overspeed protection systems. The search power of the proposed LJaya-TVAC algorithm for finding the optimal solutions is first tested on the standard real-parameter unimodal and multi-modal functions with dimensions of 30-100, and then tested on various types of nonlinear mixed-integer RRAPs. The results are compared with the original Jaya algorithm and the best results reported in the recent literature. The optimal results obtained with the proposed LJaya-TVAC algorithm provide evidence for its better and acceptable optimization performance compared to the original Jaya algorithm and other reported optimal results.

Towards cost-effective reliability through visualization of the reliability option space

NASA Technical Reports Server (NTRS)

Feather, Martin S.

2004-01-01

In planning a complex system's development there can be many options to improve its reliability. Typically their sum total cost exceeds the budget available, so it is necessary to select judiciously from among them. Reliability models can be employed to calculate the cost and reliability implications of a candidate selection.

Validity and Reliability of the Italian Version of the Functioning Assessment Short Test (FAST) in Bipolar Disorder

PubMed Central

Moro, Maria Francesca; Colom, Francesc; Floris, Francesca; Pintus, Elisa; Pintus, Mirra; Contini, Francesca; Carta, Mauro Giovanni

2012-01-01

Background: Functioning Assessment Short Test (FAST) is a brief instrument designed to assess the main functioning problems experienced by psychiatric patients, specifically bipolar patients. It includes 24 items assessing impairment or disability in six domains of functioning: autonomy, occupational functioning, cognitive functioning, financial issues, interpersonal relationships and leisure time. The aim of this study is to measure the validity and reliability of the Italian version of this instrument. Methods: Twenty-four patients with DSM-IV TR bipolar disorder and 20 healthy controls were recruited and evaluated in three private clinics in Cagliari (Sardinia, Italy). The psychometric properties of FAST (feasibility, internal consistency, concurrent validity, discriminant validity (patients vs controls and eutimic patients vs manic and depressed), and test-retest reliability were analyzed. Results: The internal consistency obtained was very high with a Cronbach's alpha of 0.955. A highly significant negative correlation with GAF was obtained (r = -0.9; p < 0.001) pointing to a reasonable degree of concurrent validity. FAST show a good test-retest reliability between two independent evaluation differing of one week (mean K =0.73). The total FAST scores were lower in controls as compared with Bipolar Patients and in Euthimic patients compared with Depressed or Manic. Conclusion: The Italian version of the FAST showed similar psychometrics properties as far as regard internal consistency and discriminant validity of the original version and show a good test retest reliability measure by means of K statistics. PMID:22905035

Reliability Technology to Achieve Insertion of Advanced Packaging (RELTECH) program

NASA Astrophysics Data System (ADS)

Fayette, Daniel F.; Speicher, Patricia; Stoklosa, Mark J.; Evans, Jillian V.; Evans, John W.; Gentile, Mike; Pagel, Chuck A.; Hakim, Edward

1993-08-01

A joint military-commercial effort to evaluate multichip module (MCM) structures is discussed. The program, Reliability Technology to Achieve Insertion of Advanced Packaging (RELTECH), has been designed to identify the failure mechanisms that are possible in MCM structures. The RELTECH test vehicles, technical assessment task, product evaluation plan, reliability modeling task, accelerated and environmental testing, and post-test physical analysis and failure analysis are described. The information obtained through RELTECH can be used to address standardization issues, through development of cost effective qualification and appropriate screening criteria, for inclusion into a commercial specification and the MIL-H-38534 general specification for hybrid microcircuits.

Reliability Technology to Achieve Insertion of Advanced Packaging (RELTECH) program

NASA Technical Reports Server (NTRS)

Fayette, Daniel F.; Speicher, Patricia; Stoklosa, Mark J.; Evans, Jillian V.; Evans, John W.; Gentile, Mike; Pagel, Chuck A.; Hakim, Edward

1993-01-01

A joint military-commercial effort to evaluate multichip module (MCM) structures is discussed. The program, Reliability Technology to Achieve Insertion of Advanced Packaging (RELTECH), has been designed to identify the failure mechanisms that are possible in MCM structures. The RELTECH test vehicles, technical assessment task, product evaluation plan, reliability modeling task, accelerated and environmental testing, and post-test physical analysis and failure analysis are described. The information obtained through RELTECH can be used to address standardization issues, through development of cost effective qualification and appropriate screening criteria, for inclusion into a commercial specification and the MIL-H-38534 general specification for hybrid microcircuits.

An accurate and efficient reliability-based design optimization using the second order reliability method and improved stability transformation method

NASA Astrophysics Data System (ADS)

Meng, Zeng; Yang, Dixiong; Zhou, Huanlin; Yu, Bo

2018-05-01

The first order reliability method has been extensively adopted for reliability-based design optimization (RBDO), but it shows inaccuracy in calculating the failure probability with highly nonlinear performance functions. Thus, the second order reliability method is required to evaluate the reliability accurately. However, its application for RBDO is quite challenge owing to the expensive computational cost incurred by the repeated reliability evaluation and Hessian calculation of probabilistic constraints. In this article, a new improved stability transformation method is proposed to search the most probable point efficiently, and the Hessian matrix is calculated by the symmetric rank-one update. The computational capability of the proposed method is illustrated and compared to the existing RBDO approaches through three mathematical and two engineering examples. The comparison results indicate that the proposed method is very efficient and accurate, providing an alternative tool for RBDO of engineering structures.

Illustrated structural application of universal first-order reliability method

NASA Technical Reports Server (NTRS)

Verderaime, V.

1994-01-01

The general application of the proposed first-order reliability method was achieved through the universal normalization of engineering probability distribution data. The method superimposes prevailing deterministic techniques and practices on the first-order reliability method to surmount deficiencies of the deterministic method and provide benefits of reliability techniques and predictions. A reliability design factor is derived from the reliability criterion to satisfy a specified reliability and is analogous to the deterministic safety factor. Its application is numerically illustrated on several practical structural design and verification cases with interesting results and insights. Two concepts of reliability selection criteria are suggested. Though the method was developed to support affordable structures for access to space, the method should also be applicable for most high-performance air and surface transportation systems.

76 FR 73608 - Reliability Technical Conference, North American Electric Reliability Corporation, Public Service...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-29

... or municipal authority play in forming your bulk power system reliability plans? b. Do you support..., North American Electric Reliability Corporation (NERC) Nick Akins, CEO of American Electric Power (AEP..., EL11-62-000] Reliability Technical Conference, North American Electric Reliability Corporation, Public...

Intra and interrater reliability of spinal sagittal curves and mobility using pocket goniometer IncliMed® in healthy subjects.

PubMed

Alderighi, Marzia; Ferrari, Raffaello; Maghini, Irene; Del Felice, Alessandra; Masiero, Stefano

2016-11-21

Radiographic examination is the gold standard to evaluate spine curves, but ionising radiations limit routine use. Non-invasive methods, such as skin-surface goniometer (IncliMed®) should be used instead. To evaluate intra- and interrater reliability to assess sagittal curves and mobility of the spine with IncliMed®. a reliability study on agonistic football players. Thoracic kyphosis, lumbar lordosis and mobility of the spine were assessed by IncliMed®. Measurements were repeated twice by each examiner during the same session with between-rater blinding. Intrarater and interrater reliability were measured by Intraclass Correlation Coefficient (ICC), 95% Confidence Interval (CI 95%) and Standard Error of Measurement (SEM). Thirty-four healthy female football players (19.17 ± 4.52 years) were enrolled. Statistical results showed high intrarater (0.805-0.923) and interrater (0.701-0.886) reliability (ICC > 0.8). The obtained intra- and interrater SEM were low, with overall absolute intrarater values between 1.39° and 2.76° and overall interrater values between 1.71° and 4.25°. IncliMed® provides high intra- and interrater reliability in healthy subjects, with limited Standard Error of Measurement. These results encourage its use in clinical practice and scientific research.

Main results and experience obtained on Mir space station and experiment program for Russian segment of ISS.

PubMed

Utkin, V F; Lukjashchenko, V I; Borisov, V V; Suvorov, V V; Tsymbalyuk, M M

2003-07-01

This article presents main scientific and practical results obtained in course of scientific and applied research and experiments on Mir space station. Based on Mir experience, processes of research program formation for the Russian Segment of the ISS are briefly described. The major trends of activities planned in the frames of these programs as well as preliminary results of increment research programs implementation in the ISS' first missions are also presented. c2003 Elsevier Science Ltd. All rights reserved.

The Effect of Anchors and Training on the Reliability of Voice Quality Ratings for Different Types of Speech Stimuli.

PubMed

Brinca, Lilia; Batista, Ana Paula; Tavares, Ana Inês; Pinto, Patrícia N; Araújo, Lara

2015-11-01

The main objective of the present study was to investigate if the type of voice stimuli-sustained vowel, oral reading, and connected speech-results in good intrarater and interrater agreement/reliability. A short-term panel study was performed. Voice samples from 30 native European Portuguese speakers were used in the present study. The speech materials used were (1) the sustained vowel /a/, (2) oral reading of the European Portuguese version of "The Story of Arthur the Rat," and (3) connected speech. After an extensive training with textual and auditory anchors, the judges were asked to rate the severity of dysphonic voice stimuli using the phonation dimensions G, R, and B from the GRBAS scale. The voice samples were judged 6 months and 1 year after the training. Intrarater agreement and reliability were generally very good for all the phonation dimensions and voice stimuli. The highest interrater reliability was obtained using the oral reading stimulus, particularly for phonation dimensions grade (G) and breathiness (B). Roughness (R) was the voice quality that was the most difficult to evaluate, leading to interrater unreliability in all voice quality ratings. Extensive training using textual and auditory anchors and the use of anchors during the voice evaluations appear to be good methods for auditory-perceptual evaluation of dysphonic voices. The best results of interrater reliability were obtained when the oral reading stimulus was used. Breathiness appears to be a voice quality that is easier to evaluate than roughness. Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Quantified Risk Ranking Model for Condition-Based Risk and Reliability Centered Maintenance

NASA Astrophysics Data System (ADS)

Chattopadhyaya, Pradip Kumar; Basu, Sushil Kumar; Majumdar, Manik Chandra

2017-06-01

In the recent past, risk and reliability centered maintenance (RRCM) framework is introduced with a shift in the methodological focus from reliability and probabilities (expected values) to reliability, uncertainty and risk. In this paper authors explain a novel methodology for risk quantification and ranking the critical items for prioritizing the maintenance actions on the basis of condition-based risk and reliability centered maintenance (CBRRCM). The critical items are identified through criticality analysis of RPN values of items of a system and the maintenance significant precipitating factors (MSPF) of items are evaluated. The criticality of risk is assessed using three risk coefficients. The likelihood risk coefficient treats the probability as a fuzzy number. The abstract risk coefficient deduces risk influenced by uncertainty, sensitivity besides other factors. The third risk coefficient is called hazardous risk coefficient, which is due to anticipated hazards which may occur in the future and the risk is deduced from criteria of consequences on safety, environment, maintenance and economic risks with corresponding cost for consequences. The characteristic values of all the three risk coefficients are obtained with a particular test. With few more tests on the system, the values may change significantly within controlling range of each coefficient, hence `random number simulation' is resorted to obtain one distinctive value for each coefficient. The risk coefficients are statistically added to obtain final risk coefficient of each critical item and then the final rankings of critical items are estimated. The prioritization in ranking of critical items using the developed mathematical model for risk assessment shall be useful in optimization of financial losses and timing of maintenance actions.

Test-retest reliability of the assessment of postural stability in typically developing children and in hearing impaired children.

PubMed

De Kegel, A; Dhooge, I; Cambier, D; Baetens, T; Palmans, T; Van Waelvelde, H

2011-04-01

The purpose of this study was to establish test-retest reliability of centre of pressure (COP) measurements obtained by an AccuGait portable forceplate (ACG), mean COG sway velocity measured by a Basic Balance Master (BBM) and clinical balance tests in children with and without balance difficulties. 49 typically developing children and 23 hearing impaired children, with a higher risk for stability problems, between 6 and 12 years of age participated. Each child performed the modified Clinical Test of Sensory Interaction on Balance (mCTSIB), Unilateral Stance (US) and Tandem Stance on ACG, mCTSIB and US on BBM and clinical balance tests: one-leg standing, balance beam walking and one-leg hopping. All subjects completed 2 test sessions on 2 different days in the same week assessed by the same examiner. Among COP measurements obtained by the ACG, mean sway velocity was the most reliable parameter with all ICCs higher than 0.72. The standard deviation (SD) of sway velocity, sway area, SD of anterior-posterior and SD of medio-lateral COP data showed moderate to excellent reliability with ICCs between 0.55 and 0.96 but some caution must be taken into account in some conditions. BBM is less reliable but clinical balance tests are as reliable as ACG. Hearing impaired children exhibited better relative reliability (ICC) and comparable absolute reliability (SEM) for most balance parameters compared to typically developing children. Reliable information regarding postural stability of typically developing children and hearing impaired children may be obtained utilizing COP measurements generated by an AccuGait system and clinical balance tests. Copyright © 2011 Elsevier B.V. All rights reserved.

Fatigue reliability of deck structures subjected to correlated crack growth

NASA Astrophysics Data System (ADS)

Feng, G. Q.; Garbatov, Y.; Guedes Soares, C.

2013-12-01

The objective of this work is to analyse fatigue reliability of deck structures subjected to correlated crack growth. The stress intensity factors of the correlated cracks are obtained by finite element analysis and based on which the geometry correction functions are derived. The Monte Carlo simulations are applied to predict the statistical descriptors of correlated cracks based on the Paris-Erdogan equation. A probabilistic model of crack growth as a function of time is used to analyse the fatigue reliability of deck structures accounting for the crack propagation correlation. A deck structure is modelled as a series system of stiffened panels, where a stiffened panel is regarded as a parallel system composed of plates and are longitudinal. It has been proven that the method developed here can be conveniently applied to perform the fatigue reliability assessment of structures subjected to correlated crack growth.

Efficient reliability analysis of structures with the rotational quasi-symmetric point- and the maximum entropy methods

NASA Astrophysics Data System (ADS)

Xu, Jun; Dang, Chao; Kong, Fan

2017-10-01

This paper presents a new method for efficient structural reliability analysis. In this method, a rotational quasi-symmetric point method (RQ-SPM) is proposed for evaluating the fractional moments of the performance function. Then, the derivation of the performance function's probability density function (PDF) is carried out based on the maximum entropy method in which constraints are specified in terms of fractional moments. In this regard, the probability of failure can be obtained by a simple integral over the performance function's PDF. Six examples, including a finite element-based reliability analysis and a dynamic system with strong nonlinearity, are used to illustrate the efficacy of the proposed method. All the computed results are compared with those by Monte Carlo simulation (MCS). It is found that the proposed method can provide very accurate results with low computational effort.

Reliability in perceptual analysis of voice quality.

PubMed

Bele, Irene Velsvik

2005-12-01

This study focuses on speaking voice quality in male teachers (n = 35) and male actors (n = 36), who represent untrained and trained voice users, because we wanted to investigate normal and supranormal voices. In this study, both substantial and methodologic aspects were considered. It includes a method for perceptual voice evaluation, and a basic issue was rater reliability. A listening group of 10 listeners, 7 experienced speech-language therapists, and 3 speech-language therapist students evaluated the voices by 15 vocal characteristics using VA scales. Two sets of voice signals were investigated: text reading (2 loudness levels) and sustained vowel (3 levels). The results indicated a high interrater reliability for most perceptual characteristics. Connected speech was evaluated more reliably, especially at the normal level, but both types of voice signals were evaluated reliably, although the reliability for connected speech was somewhat higher than for vowels. Experienced listeners tended to be more consistent in their ratings than did the student raters. Some vocal characteristics achieved acceptable reliability even with a smaller panel of listeners. The perceptual characteristics grouped in 4 factors reflected perceptual dimensions.

Validity and Reliability of the Filipino Reflux Symptom Index.

PubMed

Lapeña, José Florencio F; Ambrocio, Giancarla Marie C; Carrillo, Ryner Jose D

2017-05-01

This study aimed to establish validity and reliability of the Filipino Reflux Symptom Index (FRSI) and to test it among patients with laryngopharyngeal reflux (LPR) before and after 6 months' trial of rabeprazole. A case-control study was carried out. There were 35 LPR patients and 30 controls who were twice-administered the FRSI and Filipino Voice Handicap Index (FVHI) for test-retest reliability, and videostroboscopy was performed to obtain baseline reflux finding scores (RFSs). Patients took rabeprazole 20 mg twice daily for 6 months. The FRSI and FVHI were readministered a third time, repeat videostroboscopy was performed, and repeat RFS was obtained. Reliability, validity, and internal consistency were computed. A total of 58 participants, 29 patients and controls each, aged 22-65 years completed the study. FVHI 2:1 and FRSI 2:1 significantly correlated with no significant differences between FRSI 2:1. FRSI had good item-total correlations indicating psychometrically sound items. There were significant differences between patients and controls for FRSI scores and mean scores. FRSI 3 scores were significantly lower than FRSI 1 scores, suggesting symptoms improved after treatment. There were no significant differences between RFS 2 and 1. Significant differences between FRSI 3 and 1, but not between FVHI 3 and 1, suggest the FRSI was more sensitive to changes in reflux after 6 months' intervention than the FVHI. The FRSI is a valid and reliable tool for assessing LPR symptoms and may be used for primary care screening among Filipinos. Initial response to a 2-week empirical proton pump inhibitor trial may support an impression of LPR; non-response warrants specialist referral for further investigation. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

[Intra-rater Reliability for the Questionnaire on Activity Limitations and Participation Restrictions of Children With ADHD].

PubMed

Salamanca Duque, Luisa Matilde; Naranjo Aristizábal, María Mercedes; Gutiérrez Ríos, Gladys Helena; Prieto, Jaime Bayona

2014-03-01

Questionnaires for evaluating activity limitations and participation restrictions in children with ADHD (CLARP-TDAH) has recently been developed in Colombia, based on the suggestions made by the WHO from the International Classification of Functioning, Disability and Health (ICF), allowing clinical evaluation beyond an evaluation of the functionality and functioning of children in their family and school environments. Previous research with the questionnaire proved useful in the multidisciplinary approach of Colombian children with ADHD. This study determines the level of intra-rater reliability for questionnaires CLARP-TDAH Parents and Teachers. The study included a non-random sample of 203 Colombian children attending school and diagnosed with ADHD. Intra-rater reliability and the reproducibility of the results was determined using the Kappa index. The informants were parents and teachers. Kappa values >0.7 were obtained for the intra-rater reliability of the questionnaire domains of CLARP-TDAH Parents, while for CLARP-TDAH Teachers domains these values were >0.8. CLARP-TDAH questionnaires are a tool with a good level of intra-rater reliability, which allows a reliable assessment of activity limitations and participation restrictions in order to determine the level of functioning at home and school. Copyright © 2014 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

Scaled CMOS Technology Reliability Users Guide

NASA Technical Reports Server (NTRS)

White, Mark

2010-01-01

The desire to assess the reliability of emerging scaled microelectronics technologies through faster reliability trials and more accurate acceleration models is the precursor for further research and experimentation in this relevant field. The effect of semiconductor scaling on microelectronics product reliability is an important aspect to the high reliability application user. From the perspective of a customer or user, who in many cases must deal with very limited, if any, manufacturer's reliability data to assess the product for a highly-reliable application, product-level testing is critical in the characterization and reliability assessment of advanced nanometer semiconductor scaling effects on microelectronics reliability. A methodology on how to accomplish this and techniques for deriving the expected product-level reliability on commercial memory products are provided.Competing mechanism theory and the multiple failure mechanism model are applied to the experimental results of scaled SDRAM products. Accelerated stress testing at multiple conditions is applied at the product level of several scaled memory products to assess the performance degradation and product reliability. Acceleration models are derived for each case. For several scaled SDRAM products, retention time degradation is studied and two distinct soft error populations are observed with each technology generation: early breakdown, characterized by randomly distributed weak bits with Weibull slope (beta)=1, and a main population breakdown with an increasing failure rate. Retention time soft error rates are calculated and a multiple failure mechanism acceleration model with parameters is derived for each technology. Defect densities are calculated and reflect a decreasing trend in the percentage of random defective bits for each successive product generation. A normalized soft error failure rate of the memory data retention time in FIT/Gb and FIT/cm2 for several scaled SDRAM generations is

Responsiveness to change and reliability of measurement of radiographic joint space width in osteoarthritis of the knee: a systematic review.

PubMed

Reichmann, W M; Maillefert, J F; Hunter, D J; Katz, J N; Conaghan, P G; Losina, E

2011-05-01

The goal of this systematic review was to report the responsiveness to change and reliability of conventional radiographic joint space width (JSW) measurement. We searched the PubMed and Embase databases using the following search criteria: [osteoarthritis (OA) (MeSH)] AND (knee) AND (X-ray OR radiography OR diagnostic imaging OR radiology OR disease progression) AND (joint space OR JSW or disease progression). We assessed responsiveness by calculating the standardized response mean (SRM). We assessed reliability using intra- and inter-reader intra-class correlation (ICC) and coefficient of variation (CV). Random-effects models were used to pool results from multiple studies. Results were stratified by study duration, design, techniques of obtaining radiographs, and measurement method. We identified 998 articles using the search terms. Of these, 32 articles (43 estimates) reported data on responsiveness of JSW measurement and 24 (50 estimates) articles reported data on measures of reliability. The overall pooled SRM was 0.33 [95% confidence interval (CI): 0.26, 0.41]. Responsiveness of change in JSW measurement was improved substantially in studies of greater than 2 years duration (0.57). Further stratifying this result in studies of greater than 2 years duration, radiographs obtained with the knee in a flexed position yielded an SRM of 0.71. Pooled intra-reader ICC was estimated at 0.97 (95% CI: 0.92, 1.00) and the intra-reader CV estimated at 3.0 (95% CI: 2.0, 4.0). Pooled inter-reader ICC was estimated at 0.93 (95% CI: 0.86, 0.99) and the inter-reader CV estimated at 3.4% (95% CI: 1.3%, 5.5%). Measurement of JSW obtained from radiographs in persons with knee is reliable. These data will be useful to clinicians who are planning RCTs where the change in minimum JSW is the outcome of interest. Copyright © 2011 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

25 CFR 162.539 - Must I obtain a WEEL before obtaining a WSR lease?

Code of Federal Regulations, 2014 CFR

2014-04-01

... AND PERMITS Wind and Solar Resource Leases Wsr Leases § 162.539 Must I obtain a WEEL before obtaining... direct result of energy resource information gathered from a WEEL activity, obtaining a WEEL is not a...

25 CFR 162.539 - Must I obtain a WEEL before obtaining a WSR lease?

Code of Federal Regulations, 2013 CFR

2013-04-01

... AND PERMITS Wind and Solar Resource Leases Wsr Leases § 162.539 Must I obtain a WEEL before obtaining... direct result of energy resource information gathered from a WEEL activity, obtaining a WEEL is not a...

NREL to Host Ninth Annual PV Reliability Workshop | News | NREL

Science.gov Websites

share research leading to more durable and reliable PV modules, thus reducing the cost of solar to Host Ninth Annual PV Reliability Workshop NREL to Host Ninth Annual PV Reliability Workshop their results during a poster session at the 2017 PV Reliability Workshop. 4 people consult two

Apollo experience report: Reliability and quality assurance

NASA Technical Reports Server (NTRS)

Sperber, K. P.

1973-01-01

The reliability of the Apollo spacecraft resulted from the application of proven reliability and quality techniques and from sound management, engineering, and manufacturing practices. Continual assessment of these techniques and practices was made during the program, and, when deficiencies were detected, adjustments were made and the deficiencies were effectively corrected. The most significant practices, deficiencies, adjustments, and experiences during the Apollo Program are described in this report. These experiences can be helpful in establishing an effective base on which to structure an efficient reliability and quality assurance effort for future space-flight programs.

Reliability and Validity Study of the Chamorro Assisted Gait Scale for People with Sprained Ankles, Walking with Forearm Crutches

PubMed Central

Ridao-Fernández, Carmen; Ojeda, Joaquín; Benítez-Lugo, Marisa; Sevillano, José Luis

2016-01-01

Objective The aim of this study was to design and validate a functional assessment scale for assisted gait with forearm crutches (Chamorro Assisted Gait Scale—CHAGS) and to assess its reliability in people with sprained ankles. Design Thirty subjects who suffered from sprained ankle (anterior talofibular ligament first and second degree) were included in the study. A modified Delphi technique was used to obtain the content validity. The selected items were: pelvic and scapular girdle dissociation(1), deviation of Center of Gravity(2), crutch inclination(3), steps rhythm(4), symmetry of step length(5), cross support(6), simultaneous support of foot and crutch(7), forearm off(8), facing forward(9) and fluency(10). Two raters twice visualized the gait of the sample subjects which were recorded. The criterion-related validity was determined by correlation between CHAGS and Coding of eight criteria of qualitative gait analysis (Viel Coding). Internal consistency and inter and intra-rater reliability were also tested. Results CHAGS obtained a high and negative correlation with Viel Coding. We obtained a good internal consistency and the intra-class correlation coefficients oscillated between 0.97 and 0.99, while the minimal detectable changes were acceptable. Conclusion CHAGS scale is a valid and reliable tool for assessing assisted gait with crutches in people with sprained ankles to perform partial relief of lower limbs. PMID:27168236

Translation, cross-cultural adaptation to Brazilian- Portuguese and reliability analysis of the instrument Rapid Entire Body Assessment-REBA

PubMed Central

Lamarão, Andressa M.; Costa, Lucíola C. M.; Comper, Maria L. C.; Padula, Rosimeire S.

2014-01-01

Background: Observational instruments, such as the Rapid Entire Body Assessment, quickly assess biomechanical risks present in the workplace. However, in order to use these instruments, it is necessary to conduct the translational/cross-cultural adaptation of the instrument and test its measurement properties. Objectives: To perform the translation and the cross-cultural adaptation to Brazilian-Portuguese and test the reliability of the REBA instrument. Method: The procedures of translation and cross-cultural adaptation to Brazilian-Portuguese were conducted following proposed guidelines that involved translation, synthesis of translations, back translation, committee review and testing of the pre-final version. In addition, reliability and the intra- and inter-rater percent agreement were obtained with the Linear Weighted Kappa Coefficient that was associated with the 95% Confidence Interval and the cross tabulation 2×2. Results : The procedures for translation and adaptation were adequate and the necessary adjustments were conducted on the instrument. The intra- and inter-rater reliability showed values of 0.104 to 0.504, respectively, ranging from very poor to moderate. The percentage agreement values ranged from 5.66% to 69.81%. The percentage agreement was closer to 100% at the item 'upper arm' (69.81%) for the Intra-rater 1 and at the items 'legs' and 'upper arm' for the Intra-rater 2 (62.26%). Conclusions: The processes of translation and cross-cultural adaptation were conducted on the REBA instrument and the Brazilian version of the instrument was obtained. However, despite the reliability of the tests used to correct the translated and adapted version, the reliability values are unacceptable according to the guidelines standard, indicating that the reliability must be re-evaluated. Therefore, caution in the interpretation of the biomechanical risks measured by this instrument should be taken. PMID:25003273

Validity and Reliability of a Digital Inclinometer to Assess Knee Joint Position Sense in an Open Kinetic Chain.

PubMed

Romero-Franco, Natalia; Montaño-Munuera, Juan Antonio; Fernández-Domínguez, Juan Carlos; Jiménez-Reyes, Pedro

2017-12-18

New methods are being validated to easily evaluate the knee joint position sense (JPS) due to its role in sports movement and the risk of injury. However, no studies to date have considered the open kinetic chain (OKC) technique, despite the biomechanical differences compared to closed kinetic chain movements. To analyze the validity and reliability of a digital inclinometer to measure the knee JPS in the OKC movement. The validity, inter-tester and intra-tester reliability of a digital inclinometer for measuring knee JPS were evaluated. Sports research laboratory. Eighteen athletes (11 males and 7 females; 28.4 ± 6.6 years; 71.9 ± 14.0 kg; 1.77 ± 0.09 m; 22.8 ± 3.2 kg/m 2 ) voluntary participated in this study. Absolute angular error (AAE), relative angular error (RAE) and variable angular error (VAE) of knee JPS in an OKC. Intraclass correlation coefficient (ICC) and standard error of the mean (SEM) were calculated to determine the validity and reliability of the inclinometer. Data showed excellent validity of the inclinometer to obtain proprioceptive errors compared to the video analysis in JPS tasks (AAE: ICC = 0.981, SEM = 0.08; RAE: ICC = 0.974, SEM = 0.12; VAE: ICC = 0.973, SEM = 0.07). Inter-tester reliability was also excellent for all the proprioceptive errors (AAE: ICC = 0.967, SEM = 0.04; RAE: ICC = 0.974, SEM = 0.03; VAE: ICC = 0.939, SEM = 0.08). Similar results were obtained for intra-tester reliability (AAE: ICC = 0.861, SEM = 0.1; RAE: ICC = 0.894, SEM = 0.1; VAE: ICC = 0.700, SEM = 0.2). The digital inclinometer is a valid and reliable method to assess the knee JPS in OKC. Sport professionals may evaluate the knee JPS to monitor its deterioration during training or improvements throughout the rehabilitation process.

[Evaluation of Suicide Risk Levels in Hospitals: Validity and Reliability Tests].

PubMed

Macagnino, Sandro; Steinert, Tilman; Uhlmann, Carmen

2018-05-01

Examination of in-hospital suicide risk levels concerning their validity and their reliability. The internal suicide risk levels were evaluated in a cross sectional study of in 163 inpatients. A reliability check was performed via determining interrater-reliability of senior physician, therapist and the responsible nurse. Within the scope of the validity check, we conducted analyses of criterion validity and construct validity. For the total sample an "acceptable" to "good" interrater-reliability (Kendalls W = .77) of suicide risk levels were obtained. Schizophrenic disorders showed the lowest values, for personality disorders we found the highest level of interrater-reliability. When examining the criterion validity, Item-9 of the BDI-II is substantial correlated to our suicide risk levels (ρ m  = .54, p < .01). Within the scope of construct validity check, affective disorders showed the highest correlation (ρ = .77), compatible also with "convergent validity". They differed with schizophrenic disorders which showed the least concordance (ρ = .43). In-hospital suicide risk levels may represent an important contribution to the assessment of suicidal behavior of inpatients experiencing psychiatric treatment due to their overall good validity and reliability. © Georg Thieme Verlag KG Stuttgart · New York.

Application of phase correction to improve the interpretation of crude oil spectra obtained using 7 T Fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Cho, Yunju; Qi, Yulin; O'Connor, Peter B; Barrow, Mark P; Kim, Sunghwan

2014-01-01

In this study, a phase-correction technique was applied to the study of crude oil spectra obtained using a 7 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). 7 T FT-ICR MS had not been widely used for oil analysis due to the lower resolving power compared with high field FT-ICR MS. For low field instruments, usage of data that has not been phase-corrected results in an inability to resolve critical mass splits of C3 and SH4 (3.4 mDa), and (13)C and CH (4.5 mDa). This results in incorrect assignments of molecular formulae, and discontinuous double bond equivalents (DBE) and carbon number distributions of S1, S2, and hydrocarbon classes are obtained. Application of phase correction to the same data, however, improves the reliability of assignments and produces continuous DBE and carbon number distributions. Therefore, this study clearly demonstrates that phase correction improves data analysis and the reliability of assignments of molecular formulae in crude oil anlayses.

First archeointensity results from Portuguese potteries (1550-1750 AD)

NASA Astrophysics Data System (ADS)

Hartmann, Gelvam A.; Trindade, Ricardo I. F.; Goguitchaichvili, Avto; Etchevarne, Carlos; Morales, Juan; Afonso, Marisa C.

2009-01-01

Geomagnetic field variations at archeomagnetic timescales can be obtained from well-dated heated structures and archeological potsherds. Here, we present the first archeointensity results obtained on Portuguese ceramics (1550 to 1750 AD) collected at Brazilian archeological sites. The results are compared to those obtained from Western Europe and currently available geomagnetic field models. Continuous thermomagnetic and IRM acquisitions curves indicate that Ti-poor titanomagnetite is responsible for the remanence in these ceramic fragments. Five fragments (24 samples) out of twelve analyzed yielded reliable intensity estimates. The row archeointensity data were corrected for TRM anisotropy and cooling rate effect. The mean dipole moments are obtained for three different age intervals: 1550±30 AD, 1600±30 AD and 1750±50 AD. Mean intensities vary from 37.9±4.2 μT to 54.8±7.6 μT in agreement with the previously reported data for 1550 AD and 1750 AD. Relatively weaker, but still highly dispersed, values were obtained for 1600 AD ceramics.

Reliability and commercialization of oxidized VCSEL

NASA Astrophysics Data System (ADS)

Li, Alice; Pan, Jin-Shan; Lai, Horng-Ching; Lee, Bor-Lin; Wu, Jack; Lin, Yung-Sen; Huo, Tai-Chan; Wu, Calvin; Huang, Kai-Feng

2003-06-01

The reliability of oxidized VCSEL has similar result to implanted VCSEL. This paper presents our work on reliability data of oxidized VCSEL device and also the comparison with implanted VCSEL. The MTTF of oxidized VCSEL is 2.73 x 106 hrs at 55°C, 6 mA and failure rate ~ 1 FITs for the first 2 years operation. The reliability data of oxidized VCSEL includes activation energy, MTTF (mean-time-to failure), failure rate prediction, and 85°C / 85% humidity test will be presented below. Commercialization of oxidized VCSEL is demonstrated such as VCSEL structure, manufacturing facility, and packaging. A cost effective approach is key to its success in applications such as Datacomm.

RGCA: A Reliable GPU Cluster Architecture for Large-Scale Internet of Things Computing Based on Effective Performance-Energy Optimization

PubMed Central

Chen, Qingkui; Zhao, Deyu; Wang, Jingjuan

2017-01-01

This paper aims to develop a low-cost, high-performance and high-reliability computing system to process large-scale data using common data mining algorithms in the Internet of Things (IoT) computing environment. Considering the characteristics of IoT data processing, similar to mainstream high performance computing, we use a GPU (Graphics Processing Unit) cluster to achieve better IoT services. Firstly, we present an energy consumption calculation method (ECCM) based on WSNs. Then, using the CUDA (Compute Unified Device Architecture) Programming model, we propose a Two-level Parallel Optimization Model (TLPOM) which exploits reasonable resource planning and common compiler optimization techniques to obtain the best blocks and threads configuration considering the resource constraints of each node. The key to this part is dynamic coupling Thread-Level Parallelism (TLP) and Instruction-Level Parallelism (ILP) to improve the performance of the algorithms without additional energy consumption. Finally, combining the ECCM and the TLPOM, we use the Reliable GPU Cluster Architecture (RGCA) to obtain a high-reliability computing system considering the nodes’ diversity, algorithm characteristics, etc. The results show that the performance of the algorithms significantly increased by 34.1%, 33.96% and 24.07% for Fermi, Kepler and Maxwell on average with TLPOM and the RGCA ensures that our IoT computing system provides low-cost and high-reliability services. PMID:28777325

RGCA: A Reliable GPU Cluster Architecture for Large-Scale Internet of Things Computing Based on Effective Performance-Energy Optimization.

PubMed

Fang, Yuling; Chen, Qingkui; Xiong, Neal N; Zhao, Deyu; Wang, Jingjuan

2017-08-04

This paper aims to develop a low-cost, high-performance and high-reliability computing system to process large-scale data using common data mining algorithms in the Internet of Things (IoT) computing environment. Considering the characteristics of IoT data processing, similar to mainstream high performance computing, we use a GPU (Graphics Processing Unit) cluster to achieve better IoT services. Firstly, we present an energy consumption calculation method (ECCM) based on WSNs. Then, using the CUDA (Compute Unified Device Architecture) Programming model, we propose a Two-level Parallel Optimization Model (TLPOM) which exploits reasonable resource planning and common compiler optimization techniques to obtain the best blocks and threads configuration considering the resource constraints of each node. The key to this part is dynamic coupling Thread-Level Parallelism (TLP) and Instruction-Level Parallelism (ILP) to improve the performance of the algorithms without additional energy consumption. Finally, combining the ECCM and the TLPOM, we use the Reliable GPU Cluster Architecture (RGCA) to obtain a high-reliability computing system considering the nodes' diversity, algorithm characteristics, etc. The results show that the performance of the algorithms significantly increased by 34.1%, 33.96% and 24.07% for Fermi, Kepler and Maxwell on average with TLPOM and the RGCA ensures that our IoT computing system provides low-cost and high-reliability services.

Reliability analysis and fault-tolerant system development for a redundant strapdown inertial measurement unit. [inertial platforms

NASA Technical Reports Server (NTRS)

Motyka, P.

1983-01-01

A methodology is developed and applied for quantitatively analyzing the reliability of a dual, fail-operational redundant strapdown inertial measurement unit (RSDIMU). A Markov evaluation model is defined in terms of the operational states of the RSDIMU to predict system reliability. A 27 state model is defined based upon a candidate redundancy management system which can detect and isolate a spectrum of failure magnitudes. The results of parametric studies are presented which show the effect on reliability of the gyro failure rate, both the gyro and accelerometer failure rates together, false alarms, probability of failure detection, probability of failure isolation, and probability of damage effects and mission time. A technique is developed and evaluated for generating dynamic thresholds for detecting and isolating failures of the dual, separated IMU. Special emphasis is given to the detection of multiple, nonconcurrent failures. Digital simulation time histories are presented which show the thresholds obtained and their effectiveness in detecting and isolating sensor failures.

MEASUREMENT: ACCOUNTING FOR RELIABILITY IN PERFORMANCE ESTIMATES.

PubMed

Waterman, Brian; Sutter, Robert; Burroughs, Thomas; Dunagan, W Claiborne

2014-01-01

When evaluating physician performance measures, physician leaders are faced with the quandary of determining whether departures from expected physician performance measurements represent a true signal or random error. This uncertainty impedes the physician leader's ability and confidence to take appropriate performance improvement actions based on physician performance measurements. Incorporating reliability adjustment into physician performance measurement is a valuable way of reducing the impact of random error in the measurements, such as those caused by small sample sizes. Consequently, the physician executive has more confidence that the results represent true performance and is positioned to make better physician performance improvement decisions. Applying reliability adjustment to physician-level performance data is relatively new. As others have noted previously, it's important to keep in mind that reliability adjustment adds significant complexity to the production, interpretation and utilization of results. Furthermore, the methods explored in this case study only scratch the surface of the range of available Bayesian methods that can be used for reliability adjustment; further study is needed to test and compare these methods in practice and to examine important extensions for handling specialty-specific concerns (e.g., average case volumes, which have been shown to be important in cardiac surgery outcomes). Moreover, it's important to note that the provider group average as a basis for shrinkage is one of several possible choices that could be employed in practice and deserves further exploration in future research. With these caveats, our results demonstrate that incorporating reliability adjustment into physician performance measurements is feasible and can notably reduce the incidence of "real" signals relative to what one would expect to see using more traditional approaches. A physician leader who is interested in catalyzing performance improvement

Intrarater reliability of measuring the patella position by ultrasonography in weight-bearing condition.

PubMed

Chen, Chia Lin; Lo, Chu Ling; Huang, Kai Chu; Huang, Chen Fu

2017-10-01

[Purpose] The aim of this study was to determine the intrarater reliability of using ultrasonography as a measurement tool to assess the patella position in a weight-bearing condition. [Subjects and Methods] Ten healthy adults participated in this study. Ultrasonography was used to assess the patella position during step down with the loading knee in flexion (0° and 20°). The distance between the patella and lateral condyle was measured to represent the patella position on the condylar groove. Two measurements were obtained on the first day and the day after 1 week by the same investigator. [Results] Excellent intrarater reliability, ranging from 0.83 to 0.93, was shown in both conditions. Standard errors of the measurements were 0.5 mm in the straight knee and 0.7 mm in the knee flexion at 20°. Minimal differences in knee flexion at 0° and knee flexion at 20° were 1.5 mm and 1.9 mm, respectively. [Conclusion] Ultrasonography is a reliable assessment tool for evaluating the positional changes of the patella in weight-bearing activities, and it can be easily used by practitioners in the clinical setting.

Validity and reliability of Optojump photoelectric cells for estimating vertical jump height.

PubMed

Glatthorn, Julia F; Gouge, Sylvain; Nussbaumer, Silvio; Stauffacher, Simone; Impellizzeri, Franco M; Maffiuletti, Nicola A

2011-02-01

Vertical jump is one of the most prevalent acts performed in several sport activities. It is therefore important to ensure that the measurements of vertical jump height made as a part of research or athlete support work have adequate validity and reliability. The aim of this study was to evaluate concurrent validity and reliability of the Optojump photocell system (Microgate, Bolzano, Italy) with force plate measurements for estimating vertical jump height. Twenty subjects were asked to perform maximal squat jumps and countermovement jumps, and flight time-derived jump heights obtained by the force plate were compared with those provided by Optojump, to examine its concurrent (criterion-related) validity (study 1). Twenty other subjects completed the same jump series on 2 different occasions (separated by 1 week), and jump heights of session 1 were compared with session 2, to investigate test-retest reliability of the Optojump system (study 2). Intraclass correlation coefficients (ICCs) for validity were very high (0.997-0.998), even if a systematic difference was consistently observed between force plate and Optojump (-1.06 cm; p < 0.001). Test-retest reliability of the Optojump system was excellent, with ICCs ranging from 0.982 to 0.989, low coefficients of variation (2.7%), and low random errors (±2.81 cm). The Optojump photocell system demonstrated strong concurrent validity and excellent test-retest reliability for the estimation of vertical jump height. We propose the following equation that allows force plate and Optojump results to be used interchangeably: force plate jump height (cm) = 1.02 × Optojump jump height + 0.29. In conclusion, the use of Optojump photoelectric cells is legitimate for field-based assessments of vertical jump height.

A validation of the construct and reliability of an emotional intelligence scale applied to nursing students1

PubMed Central

Espinoza-Venegas, Maritza; Sanhueza-Alvarado, Olivia; Ramírez-Elizondo, Noé; Sáez-Carrillo, Katia

2015-01-01

OBJECTIVE: The current study aimed to validate the construct and reliability of an emotional intelligence scale. METHOD: The Trait Meta-Mood Scale-24 was applied to 349 nursing students. The process included content validation, which involved expert reviews, pilot testing, measurements of reliability using Cronbach's alpha, and factor analysis to corroborate the validity of the theoretical model's construct. RESULTS: Adequate Cronbach coefficients were obtained for all three dimensions, and factor analysis confirmed the scale's dimensions (perception, comprehension, and regulation). CONCLUSION: The Trait Meta-Mood Scale is a reliable and valid tool to measure the emotional intelligence of nursing students. Its use allows for accurate determinations of individuals' abilities to interpret and manage emotions. At the same time, this new construct is of potential importance for measurements in nursing leadership; educational, organizational, and personal improvements; and the establishment of effective relationships with patients. PMID:25806642

Modeling and simulation of reliability of unmanned intelligent vehicles

NASA Astrophysics Data System (ADS)

Singh, Harpreet; Dixit, Arati M.; Mustapha, Adam; Singh, Kuldip; Aggarwal, K. K.; Gerhart, Grant R.

2008-04-01

Unmanned ground vehicles have a large number of scientific, military and commercial applications. A convoy of such vehicles can have collaboration and coordination. For the movement of such a convoy, it is important to predict the reliability of the system. A number of approaches are available in literature which describes the techniques for determining the reliability of the system. Graph theoretic approaches are popular in determining terminal reliability and system reliability. In this paper we propose to exploit Fuzzy and Neuro-Fuzzy approaches for predicting the node and branch reliability of the system while Boolean algebra approaches are used to determine terminal reliability and system reliability. Hence a combination of intelligent approaches like Fuzzy, Neuro-Fuzzy and Boolean approaches is used to predict the overall system reliability of a convoy of vehicles. The node reliabilities may correspond to the collaboration of vehicles while branch reliabilities will determine the terminal reliabilities between different nodes. An algorithm is proposed for determining the system reliabilities of a convoy of vehicles. The simulation of the overall system is proposed. Such simulation should be helpful to the commander to take an appropriate action depending on the predicted reliability in different terrain and environmental conditions. It is hoped that results of this paper will lead to more important techniques to have a reliable convoy of vehicles in a battlefield.

Reliability in individual monitoring service.

PubMed

Mod Ali, N

2011-03-01

As a laboratory certified to ISO 9001:2008 and accredited to ISO/IEC 17025, the Secondary Standard Dosimetry Laboratory (SSDL)-Nuclear Malaysia has incorporated an overall comprehensive system for technical and quality management in promoting a reliable individual monitoring service (IMS). Faster identification and resolution of issues regarding dosemeter preparation and issuing of reports, personnel enhancement, improved customer satisfaction and overall efficiency of laboratory activities are all results of the implementation of an effective quality system. Review of these measures and responses to observed trends provide continuous improvement of the system. By having these mechanisms, reliability of the IMS can be assured in the promotion of safe behaviour at all levels of the workforce utilising ionising radiation facilities. Upgradation of in the reporting program through a web-based e-SSDL marks a major improvement in Nuclear Malaysia's IMS reliability on the whole. The system is a vital step in providing a user friendly and effective occupational exposure evaluation program in the country. It provides a higher level of confidence in the results generated for occupational dose monitoring of the IMS, thus, enhances the status of the radiation protection framework of the country.

Extracting More Information from Passive Optical Tracking Observations for Reliable Orbit Element Generation

NASA Astrophysics Data System (ADS)

Bennett, J.; Gehly, S.

2016-09-01

This paper presents results from a preliminary method for extracting more orbital information from low rate passive optical tracking data. An improvement in the accuracy of the observation data yields more accurate and reliable orbital elements. A comparison between the orbit propagations from the orbital element generated using the new data processing method is compared with the one generated from the raw observation data for several objects. Optical tracking data collected by EOS Space Systems, located on Mount Stromlo, Australia, is fitted to provide a new orbital element. The element accuracy is determined from a comparison between the predicted orbit and subsequent tracking data or reference orbit if available. The new method is shown to result in a better orbit prediction which has important implications in conjunction assessments and the Space Environment Research Centre space object catalogue. The focus is on obtaining reliable orbital solutions from sparse data. This work forms part of the collaborative effort of the Space Environment Management Cooperative Research Centre which is developing new technologies and strategies to preserve the space environment (www.serc.org.au).

Effect of image resolution manipulation in rearfoot angle measurements obtained with photogrammetry

PubMed Central

Sacco, I.C.N.; Picon, A.P.; Ribeiro, A.P.; Sartor, C.D.; Camargo-Junior, F.; Macedo, D.O.; Mori, E.T.T.; Monte, F.; Yamate, G.Y.; Neves, J.G.; Kondo, V.E.; Aliberti, S.

2012-01-01

The aim of this study was to investigate the influence of image resolution manipulation on the photogrammetric measurement of the rearfoot static angle. The study design was that of a reliability study. We evaluated 19 healthy young adults (11 females and 8 males). The photographs were taken at 1536 pixels in the greatest dimension, resized into four different resolutions (1200, 768, 600, 384 pixels) and analyzed by three equally trained examiners on a 96-pixels per inch (ppi) screen. An experienced physiotherapist marked the anatomic landmarks of rearfoot static angles on two occasions within a 1-week interval. Three different examiners had marked angles on digital pictures. The systematic error and the smallest detectable difference were calculated from the angle values between the image resolutions and times of evaluation. Different resolutions were compared by analysis of variance. Inter- and intra-examiner reliability was calculated by intra-class correlation coefficients (ICC). The rearfoot static angles obtained by the examiners in each resolution were not different (P > 0.05); however, the higher the image resolution the better the inter-examiner reliability. The intra-examiner reliability (within a 1-week interval) was considered to be unacceptable for all image resolutions (ICC range: 0.08-0.52). The whole body image of an adult with a minimum size of 768 pixels analyzed on a 96-ppi screen can provide very good inter-examiner reliability for photogrammetric measurements of rearfoot static angles (ICC range: 0.85-0.92), although the intra-examiner reliability within each resolution was not acceptable. Therefore, this method is not a proper tool for follow-up evaluations of patients within a therapeutic protocol. PMID:22911379

Effect of image resolution manipulation in rearfoot angle measurements obtained with photogrammetry.

PubMed

Sacco, I C N; Picon, A P; Ribeiro, A P; Sartor, C D; Camargo-Junior, F; Macedo, D O; Mori, E T T; Monte, F; Yamate, G Y; Neves, J G; Kondo, V E; Aliberti, S

2012-09-01

The aim of this study was to investigate the influence of image resolution manipulation on the photogrammetric measurement of the rearfoot static angle. The study design was that of a reliability study. We evaluated 19 healthy young adults (11 females and 8 males). The photographs were taken at 1536 pixels in the greatest dimension, resized into four different resolutions (1200, 768, 600, 384 pixels) and analyzed by three equally trained examiners on a 96-pixels per inch (ppi) screen. An experienced physiotherapist marked the anatomic landmarks of rearfoot static angles on two occasions within a 1-week interval. Three different examiners had marked angles on digital pictures. The systematic error and the smallest detectable difference were calculated from the angle values between the image resolutions and times of evaluation. Different resolutions were compared by analysis of variance. Inter- and intra-examiner reliability was calculated by intra-class correlation coefficients (ICC). The rearfoot static angles obtained by the examiners in each resolution were not different (P > 0.05); however, the higher the image resolution the better the inter-examiner reliability. The intra-examiner reliability (within a 1-week interval) was considered to be unacceptable for all image resolutions (ICC range: 0.08-0.52). The whole body image of an adult with a minimum size of 768 pixels analyzed on a 96-ppi screen can provide very good inter-examiner reliability for photogrammetric measurements of rearfoot static angles (ICC range: 0.85-0.92), although the intra-examiner reliability within each resolution was not acceptable. Therefore, this method is not a proper tool for follow-up evaluations of patients within a therapeutic protocol.

Validity and reliability of a low-cost digital dynamometer for measuring isometric strength of lower limb.

PubMed

Romero-Franco, Natalia; Jiménez-Reyes, Pedro; Montaño-Munuera, Juan A

2017-11-01

Lower limb isometric strength is a key parameter to monitor the training process or recognise muscle weakness and injury risk. However, valid and reliable methods to evaluate it often require high-cost tools. The aim of this study was to analyse the concurrent validity and reliability of a low-cost digital dynamometer for measuring isometric strength in lower limb. Eleven physically active and healthy participants performed maximal isometric strength for: flexion and extension of ankle, flexion and extension of knee, flexion, extension, adduction, abduction, internal and external rotation of hip. Data obtained by the digital dynamometer were compared with the isokinetic dynamometer to examine its concurrent validity. Data obtained by the digital dynamometer from 2 different evaluators and 2 different sessions were compared to examine its inter-rater and intra-rater reliability. Intra-class correlation (ICC) for validity was excellent in every movement (ICC > 0.9). Intra and inter-tester reliability was excellent for all the movements assessed (ICC > 0.75). The low-cost digital dynamometer demonstrated strong concurrent validity and excellent intra and inter-tester reliability for assessing isometric strength in the main lower limb movements.

Reliability of Source Mechanisms for a Hydraulic Fracturing Dataset

NASA Astrophysics Data System (ADS)

Eyre, T.; Van der Baan, M.

2016-12-01

Non-double-couple components have been inferred for induced seismicity due to fluid injection, yet these components are often poorly constrained due to the acquisition geometry. Likewise non-double-couple components in microseismic recordings are not uncommon. Microseismic source mechanisms provide an insight into the fracturing behaviour of a hydraulically stimulated reservoir. However, source inversion in a hydraulic fracturing environment is complicated by the likelihood of volumetric contributions to the source due to the presence of high pressure fluids, which greatly increases the possible solution space and therefore the non-uniqueness of the solutions. Microseismic data is usually recorded on either 2D surface or borehole arrays of sensors. In many cases, surface arrays appear to constrain source mechanisms with high shear components, whereas borehole arrays tend to constrain more variable mechanisms including those with high tensile components. The abilities of each geometry to constrain the true source mechanisms are therefore called into question.The ability to distinguish between shear and tensile source mechanisms with different acquisition geometries is investigated using synthetic data. For both inversions, both P- and S- wave amplitudes recorded on three component sensors need to be included to obtain reliable solutions. Surface arrays appear to give more reliable solutions due to a greater sampling of the focal sphere, but in reality tend to record signals with a low signal to noise ratio. Borehole arrays can produce acceptable results, however the reliability is much more affected by relative source-receiver locations and source orientation, with biases produced in many of the solutions. Therefore more care must be taken when interpreting results.These findings are taken into account when interpreting a microseismic dataset of 470 events recorded by two vertical borehole arrays monitoring a horizontal treatment well. Source locations and

Reliability Correction for Functional Connectivity: Theory and Implementation

PubMed Central

Mueller, Sophia; Wang, Danhong; Fox, Michael D.; Pan, Ruiqi; Lu, Jie; Li, Kuncheng; Sun, Wei; Buckner, Randy L.; Liu, Hesheng

2016-01-01

Network properties can be estimated using functional connectivity MRI (fcMRI). However, regional variation of the fMRI signal causes systematic biases in network estimates including correlation attenuation in regions of low measurement reliability. Here we computed the spatial distribution of fcMRI reliability using longitudinal fcMRI datasets and demonstrated how pre-estimated reliability maps can correct for correlation attenuation. As a test case of reliability-based attenuation correction we estimated properties of the default network, where reliability was significantly lower than average in the medial temporal lobe and higher in the posterior medial cortex, heterogeneity that impacts estimation of the network. Accounting for this bias using attenuation correction revealed that the medial temporal lobe’s contribution to the default network is typically underestimated. To render this approach useful to a greater number of datasets, we demonstrate that test-retest reliability maps derived from repeated runs within a single scanning session can be used as a surrogate for multi-session reliability mapping. Using data segments with different scan lengths between 1 and 30 min, we found that test-retest reliability of connectivity estimates increases with scan length while the spatial distribution of reliability is relatively stable even at short scan lengths. Finally, analyses of tertiary data revealed that reliability distribution is influenced by age, neuropsychiatric status and scanner type, suggesting that reliability correction may be especially important when studying between-group differences. Collectively, these results illustrate that reliability-based attenuation correction is an easily implemented strategy that mitigates certain features of fMRI signal nonuniformity. PMID:26493163

Estimate of the Reliability in Geological Forecasts for Tunnels: Toward a Structured Approach

NASA Astrophysics Data System (ADS)

Perello, Paolo

2011-11-01

In tunnelling, a reliable geological model often allows providing an effective design and facing the construction phase without unpleasant surprises. A geological model can be considered reliable when it is a valid support to correctly foresee the rock mass behaviour, therefore preventing unexpected events during the excavation. The higher the model reliability, the lower the probability of unforeseen rock mass behaviour. Unfortunately, owing to different reasons, geological models are affected by uncertainties and a fully reliable knowledge of the rock mass is, in most cases, impossible. Therefore, estimating to which degree a geological model is reliable, becomes a primary requirement in order to save time and money and to adopt the appropriate construction strategy. The definition of the geological model reliability is often achieved by engineering geologists through an unstructured analytical process and variable criteria. This paper focusses on geological models for projects of linear underground structures and represents an effort to analyse and include in a conceptual framework the factors influencing such models. An empirical parametric procedure is then developed with the aim of obtaining an index called "geological model rating (GMR)", which can be used to provide a more standardised definition of a geological model reliability.

Reliability analysis applied to structural tests

NASA Technical Reports Server (NTRS)

Diamond, P.; Payne, A. O.

1972-01-01

The application of reliability theory to predict, from structural fatigue test data, the risk of failure of a structure under service conditions because its load-carrying capability is progressively reduced by the extension of a fatigue crack, is considered. The procedure is applicable to both safe-life and fail-safe structures and, for a prescribed safety level, it will enable an inspection procedure to be planned or, if inspection is not feasible, it will evaluate the life to replacement. The theory has been further developed to cope with the case of structures with initial cracks, such as can occur in modern high-strength materials which are susceptible to the formation of small flaws during the production process. The method has been applied to a structure of high-strength steel and the results are compared with those obtained by the current life estimation procedures. This has shown that the conventional methods can be unconservative in certain cases, depending on the characteristics of the structure and the design operating conditions. The suitability of the probabilistic approach to the interpretation of the results from full-scale fatigue testing of aircraft structures is discussed and the assumptions involved are examined.

The reliability of photoneutron cross sections for 90,91,92,94Zr

NASA Astrophysics Data System (ADS)

Varlamov, V. V.; Davydov, A. I.; Ishkhanov, B. S.; Orlin, V. N.

2018-05-01

Data on partial photoneutron reaction cross sections (γ,1n) and (γ,2n) for 90,91,92,94Zr obtained at Livermore (USA) and for 90Zr obtained at Saclay (France) were analyzed. Experimental data were obtained using quasimonoenergetic photon beams from the annihilation in flight of relativistic positrons. The method of photoneutron multiplicity sorting based on the neutron energy measuring was used to separate partial reactions. The research carried out is based on the objective of using the physical criteria of data reliability. The large systematic uncertainties were found in partial cross sections, since they do not satisfy those criteria. To obtain the reliable cross sections of the partial (γ,1n) and (γ,2n) and total (γ,1n) + (γ,2n) reactions on 90,91,92,94Zr and (γ,3n) reaction on 94Zr, the experimental-theoretical method was used. It is based on the experimental data for neutron yield cross section rather independent from the neutron multiplicity and theoretical equations of the combined photonucleon reaction model (CPNRM). Newly evaluated data are compared with experimental ones. The reasons of noticeable disagreements between those are discussed.

Hawaii Electric System Reliability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loose, Verne William; Silva Monroy, Cesar Augusto

2012-08-01

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

Time-Variant Reliability Analysis for Rubber O-Ring Seal Considering Both Material Degradation and Random Load

PubMed Central

Liao, Baopeng; Yan, Meichen; Zhang, Weifang; Zhou, Kun

2017-01-01

Due to the increase in working hours, the reliability of rubber O-ring seals used in hydraulic systems of transfer machines will change. While traditional methods can only analyze one of the material properties or seal properties, the failure of the O-ring is caused by these two factors together. In this paper, two factors are mainly analyzed: the degradation of material properties and load randomization by processing technology. Firstly, the two factors are defined in terms of material failure and seal failure, before the experimental methods of rubber materials are studied. Following this, the time-variant material properties through experiments and load distribution by monitoring the processing can be obtained. Thirdly, compressive stress and contact stress have been calculated, which was combined with the reliability model to acquire the time-variant reliability for the O-ring. Finally, the life prediction and effect of oil pressure were discussed, then compared with the actual situation. The results show a lifetime of 12 months for the O-ring calculated in this paper, and compared with the replacement records from the maintenance workshop, the result is credible. PMID:29053597

Reliability and coverage analysis of non-repairable fault-tolerant memory systems

NASA Technical Reports Server (NTRS)

Cox, G. W.; Carroll, B. D.

1976-01-01

A method was developed for the construction of probabilistic state-space models for nonrepairable systems. Models were developed for several systems which achieved reliability improvement by means of error-coding, modularized sparing, massive replication and other fault-tolerant techniques. From the models developed, sets of reliability and coverage equations for the systems were developed. Comparative analyses of the systems were performed using these equation sets. In addition, the effects of varying subunit reliabilities on system reliability and coverage were described. The results of these analyses indicated that a significant gain in system reliability may be achieved by use of combinations of modularized sparing, error coding, and software error control. For sufficiently reliable system subunits, this gain may far exceed the reliability gain achieved by use of massive replication techniques, yet result in a considerable saving in system cost.

Pocket Handbook on Reliability

DTIC Science & Technology

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 validity in measurement of true humeral retroversion by a three-dimensional cylinder fitting method.

PubMed

Saka, Masayuki; Yamauchi, Hiroki; Hoshi, Kenji; Yoshioka, Toru; Hamada, Hidetoshi; Gamada, Kazuyoshi

2015-05-01

Humeral retroversion is defined as the orientation of the humeral head relative to the distal humerus. Because none of the previous methods used to measure humeral retroversion strictly follow this definition, values obtained by these techniques vary and may be biased by morphologic variations of the humerus. The purpose of this study was 2-fold: to validate a method to define the axis of the distal humerus with a virtual cylinder and to establish the reliability of 3-dimensional (3D) measurement of humeral retroversion by this cylinder fitting method. Humeral retroversion in 14 baseball players (28 humeri) was measured by the 3D cylinder fitting method. The root mean square error was calculated to compare values obtained by a single tester and by 2 different testers using the embedded coordinate system. To establish the reliability, intraclass correlation coefficient (ICC) and precision (standard error of measurement [SEM]) were calculated. The root mean square errors for the humeral coordinate system were <1.0 mm/1.0° for comparison of all translations/rotations obtained by a single tester and <1.0 mm/2.0° for comparison obtained by 2 different testers. Assessment of reliability and precision of the 3D measurement of retroversion yielded an intratester ICC of 0.99 (SEM, 1.0°) and intertester ICC of 0.96 (SEM, 2.8°). The error in measurements obtained by a distal humerus cylinder fitting method was small enough not to affect retroversion measurement. The 3D measurement of retroversion by this method provides excellent intratester and intertester reliability. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Field reliability of competency and sanity opinions: A systematic review and meta-analysis.

PubMed

Guarnera, Lucy A; Murrie, Daniel C

2017-06-01

We know surprisingly little about the interrater reliability of forensic psychological opinions, even though courts and other authorities have long called for known error rates for scientific procedures admitted as courtroom testimony. This is particularly true for opinions produced during routine practice in the field, even for some of the most common types of forensic evaluations-evaluations of adjudicative competency and legal sanity. To address this gap, we used meta-analytic procedures and study space methodology to systematically review studies that examined the interrater reliability-particularly the field reliability-of competency and sanity opinions. Of 59 identified studies, 9 addressed the field reliability of competency opinions and 8 addressed the field reliability of sanity opinions. These studies presented a wide range of reliability estimates; pairwise percentage agreements ranged from 57% to 100% and kappas ranged from .28 to 1.0. Meta-analytic combinations of reliability estimates obtained by independent evaluators returned estimates of κ = .49 (95% CI: .40-.58) for competency opinions and κ = .41 (95% CI: .29-.53) for sanity opinions. This wide range of reliability estimates underscores the extent to which different evaluation contexts tend to produce different reliability rates. Unfortunately, our study space analysis illustrates that available field reliability studies typically provide little information about contextual variables crucial to understanding their findings. Given these concerns, we offer suggestions for improving research on the field reliability of competency and sanity opinions, as well as suggestions for improving reliability rates themselves. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

CERTS: Consortium for Electric Reliability Technology Solutions - Research Highlights

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eto, Joseph

2003-07-30

Historically, the U.S. electric power industry was vertically integrated, and utilities were responsible for system planning, operations, and reliability management. As the nation moves to a competitive market structure, these functions have been disaggregated, and no single entity is responsible for reliability management. As a result, new tools, technologies, systems, and management processes are needed to manage the reliability of the electricity grid. However, a number of simultaneous trends prevent electricity market participants from pursuing development of these reliability tools: utilities are preoccupied with restructuring their businesses, research funding has declined, and the formation of Independent System Operators (ISOs) andmore » Regional Transmission Organizations (RTOs) to operate the grid means that control of transmission assets is separate from ownership of these assets; at the same time, business uncertainty, and changing regulatory policies have created a climate in which needed investment for transmission infrastructure and tools for reliability management has dried up. To address the resulting emerging gaps in reliability R&D, CERTS has undertaken much-needed public interest research on reliability technologies for the electricity grid. CERTS' vision is to: (1) Transform the electricity grid into an intelligent network that can sense and respond automatically to changing flows of power and emerging problems; (2) Enhance reliability management through market mechanisms, including transparency of real-time information on the status of the grid; (3) Empower customers to manage their energy use and reliability needs in response to real-time market price signals; and (4) Seamlessly integrate distributed technologies--including those for generation, storage, controls, and communications--to support the reliability needs of both the grid and individual customers.« less

Reliabilities of Intraindividual Variability Indicators with Autocorrelated Longitudinal Data: Implications for Longitudinal Study Designs.

PubMed

Du, Han; Wang, Lijuan

2018-04-23

Intraindividual variability can be measured by the intraindividual standard deviation ([Formula: see text]), intraindividual variance ([Formula: see text]), estimated hth-order autocorrelation coefficient ([Formula: see text]), and mean square successive difference ([Formula: see text]). Unresolved issues exist in the research on reliabilities of intraindividual variability indicators: (1) previous research only studied conditions with 0 autocorrelations in the longitudinal responses; (2) the reliabilities of [Formula: see text] and [Formula: see text] have not been studied. The current study investigates reliabilities of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and the intraindividual mean, with autocorrelated longitudinal data. Reliability estimates of the indicators were obtained through Monte Carlo simulations. The impact of influential factors on reliabilities of the intraindividual variability indicators is summarized, and the reliabilities are compared across the indicators. Generally, all the studied indicators of intraindividual variability were more reliable with a more reliable measurement scale and more assessments. The reliabilities of [Formula: see text] were generally lower than those of [Formula: see text] and [Formula: see text], the reliabilities of [Formula: see text] were usually between those of [Formula: see text] and [Formula: see text] unless the scale reliability was large and/or the interindividual standard deviation in autocorrelation coefficients was large, and the reliabilities of the intraindividual mean were generally the highest. An R function is provided for planning longitudinal studies to ensure sufficient reliabilities of the intraindividual indicators are achieved.

Improving Reliability of a Residency Interview Process

PubMed Central

Serres, Michelle L.; Gundrum, Todd E.

2013-01-01

Objective. To improve the reliability and discrimination of a pharmacy resident interview evaluation form, and thereby improve the reliability of the interview process. Methods. In phase 1 of the study, authors used a Many-Facet Rasch Measurement model to optimize an existing evaluation form for reliability and discrimination. In phase 2, interviewer pairs used the modified evaluation form within 4 separate interview stations. In phase 3, 8 interviewers individually-evaluated each candidate in one-on-one interviews. Results. In phase 1, the evaluation form had a reliability of 0.98 with person separation of 6.56; reproducibly, the form separated applicants into 6 distinct groups. Using that form in phase 2 and 3, our largest variation source was candidates, while content specificity was the next largest variation source. The phase 2 g-coefficient was 0.787, while confirmatory phase 3 was 0.922. Process reliability improved with more stations despite fewer interviewers per station—impact of content specificity was greatly reduced with more interview stations. Conclusion. A more reliable, discriminating evaluation form was developed to evaluate candidates during resident interviews, and a process was designed that reduced the impact from content specificity. PMID:24159209

Structural reliability assessment of the Oman India Pipeline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Sharif, A.M.; Preston, R.

1996-12-31

Reliability techniques are increasingly finding application in design. The special design conditions for the deep water sections of the Oman India Pipeline dictate their use since the experience basis for application of standard deterministic techniques is inadequate. The paper discusses the reliability analysis as applied to the Oman India Pipeline, including selection of a collapse model, characterization of the variability in the parameters that affect pipe resistance to collapse, and implementation of first and second order reliability analyses to assess the probability of pipe failure. The reliability analysis results are used as the basis for establishing the pipe wall thicknessmore » requirements for the pipeline.« less

Validity and reliability of the Persian version of mobile phone addiction scale

PubMed Central

Mazaheri, Maryam Amidi; Karbasi, Mojtaba

2014-01-01

Background: With regard to large number of mobile users especially among college students in Iran, addiction to mobile phone is attracting increasing concern. There is an urgent need for reliable and valid instrument to measure this phenomenon. This study examines validity and reliability of the Persian version of mobile phone addiction scale (MPAIS) in college students. Materials and Methods: this methodological study was down in Isfahan University of Medical Sciences. One thousand one hundred and eighty students were selected by convenience sampling. The English version of the MPAI questionnaire was translated into Persian with the approach of Jones et al. (Challenges in language, culture, and modality: Translating English measures into American Sign Language. Nurs Res 2006; 55: 75-81). Its reliability was tested by Cronbach's alpha and its dimensionality validity was evaluated using Pearson correlation coefficients with other measures of mobile phone use and IAT. Construct validity was evaluated using Exploratory subscale analysis. Results: Cronbach's alpha of 0.86 was obtained for total PMPAS, for subscale1 (eight items) was 0.84, for subscale 2 (five items) was 0.81 and for subscale 3 (two items) was 0.77. There were significantly positive correlations between the score of PMPAS and IAT (r = 0.453, P < 0.001) and other measures of mobile phone use. Principal component subscale analysis yielded a three-subscale structure including: inability to control craving; feeling anxious and lost; mood improvement accounted for 60.57% of total variance. The results of discriminate validity showed that all the item's correlations with related subscale were greater than 0.5 and correlations with unrelated subscale were less than 0.5. Conclusion: Considering lack of a valid and reliable questionnaire for measuring addiction to the mobile phone, PMPAS could be a suitable instrument for measuring mobile phone addiction in future research. PMID:24778668

Effect of windowing on lithosphere elastic thickness estimates obtained via the coherence method: Results from northern South America

NASA Astrophysics Data System (ADS)

Ojeda, GermáN. Y.; Whitman, Dean

2002-11-01

The effective elastic thickness (Te) of the lithosphere is a parameter that describes the flexural strength of a plate. A method routinely used to quantify this parameter is to calculate the coherence between the two-dimensional gravity and topography spectra. Prior to spectra calculation, data grids must be "windowed" in order to avoid edge effects. We investigated the sensitivity of Te estimates obtained via the coherence method to mirroring, Hanning and multitaper windowing techniques on synthetic data as well as on data from northern South America. These analyses suggest that the choice of windowing technique plays an important role in Te estimates and may result in discrepancies of several kilometers depending on the selected windowing method. Te results from mirrored grids tend to be greater than those from Hanning smoothed or multitapered grids. Results obtained from mirrored grids are likely to be over-estimates. This effect may be due to artificial long wavelengths introduced into the data at the time of mirroring. Coherence estimates obtained from three subareas in northern South America indicate that the average effective elastic thickness is in the range of 29-30 km, according to Hanning and multitaper windowed data. Lateral variations across the study area could not be unequivocally determined from this study. We suggest that the resolution of the coherence method does not permit evaluation of small (i.e., ˜5 km), local Te variations. However, the efficiency and robustness of the coherence method in rendering continent-scale estimates of elastic thickness has been confirmed.

The Probability of Obtaining Two Statistically Different Test Scores as a Test Index

ERIC Educational Resources Information Center

Muller, Jorg M.

2006-01-01

A new test index is defined as the probability of obtaining two randomly selected test scores (PDTS) as statistically different. After giving a concept definition of the test index, two simulation studies are presented. The first analyzes the influence of the distribution of test scores, test reliability, and sample size on PDTS within classical…

An Update on Phased Array Results Obtained on the GE Counter-Rotating Open Rotor Model

NASA Technical Reports Server (NTRS)

Podboy, Gary; Horvath, Csaba; Envia, Edmane

2013-01-01

Beamform maps have been generated from 1) simulated data generated by the LINPROP code and 2) actual experimental phased array data obtained on the GE Counter-rotating open rotor model. The beamform maps show that many of the tones in the experimental data come from their corresponding Mach radius. If the phased array points to the Mach radius associated with a tone then it is likely that the tone is a result of the loading and thickness noise on the blades. In this case, the phased array correctly points to where the noise is coming from and indicates the axial location of the loudest source in the image but not necessarily the correct vertical location. If the phased array does not point to the Mach radius associated with a tone then some mechanism other than loading and thickness noise may control the amplitude of the tone. In this case, the phased array may or may not point to the actual source. If the source is not rotating it is likely that the phased array points to the source. If the source is rotating it is likely that the phased array indicates the axial location of the loudest source but not necessarily the correct vertical location. These results indicate that you have to be careful in how you interpret phased array data obtained on an open rotor since they may show the tones coming from a location other than the source location. With a subsonic tip speed open rotor the tones can come form locations outboard of the blade tips. This has implications regarding noise shielding.

On-orbit spacecraft reliability

NASA Technical Reports Server (NTRS)

Bloomquist, C.; Demars, D.; Graham, W.; Henmi, P.

1978-01-01

Operational and historic data for 350 spacecraft from 52 U.S. space programs were analyzed for on-orbit reliability. Failure rates estimates are made for on-orbit operation of spacecraft subsystems, components, and piece parts, as well as estimates of failure probability for the same elements during launch. Confidence intervals for both parameters are also given. The results indicate that: (1) the success of spacecraft operation is only slightly affected by most reported incidents of anomalous behavior; (2) the occurrence of the majority of anomalous incidents could have been prevented piror to launch; (3) no detrimental effect of spacecraft dormancy is evident; (4) cycled components in general are not demonstrably less reliable than uncycled components; and (5) application of product assurance elements is conductive to spacecraft success.

Hawaii electric system reliability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva Monroy, Cesar Augusto; Loose, Verne William

2012-09-01

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

Reliability of temporal summation and diffuse noxious inhibitory control

PubMed Central

Cathcart, Stuart; Winefield, Anthony H; Rolan, Paul; Lushington, Kurt

2009-01-01

BACKGROUND: The test-retest reliability of temporal summation (TS) and diffuse noxious inhibitory control (DNIC) has not been reported to date. Establishing such reliability would support the possibility of future experimental studies examining factors affecting TS and DNIC. Similarly, the use of manual algometry to induce TS, or an occlusion cuff to induce DNIC of TS to mechanical stimuli, has not been reported to date. Such devices may offer a simpler method than current techniques for inducing TS and DNIC, affording assessment at more anatomical locations and in more varied research settings. METHOD: The present study assessed the test-retest reliability of TS and DNIC using the above techniques. Sex differences on these measures were also investigated. RESULTS: Repeated measures ANOVA indicated successful induction of TS and DNIC, with no significant differences across test-retest occasions. Sex effects were not significant for any measure or interaction. Intraclass correlations indicated high test-retest reliability for all measures; however, there was large interindividual variation between test and retest measurements. CONCLUSION: The present results indicate acceptable within-session test-retest reliability of TS and DNIC. The results support the possibility of future experimental studies examining factors affecting TS and DNIC. PMID:20011713

Reliability of digital reactor protection system based on extenics.

PubMed

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

2016-01-01

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

Reliability of Long-Term Wave Conditions Predicted with Data Sets of Short Duration

DTIC Science & Technology

1985-03-01

the validity and reliability of predicted probable wave heights obtained from data of limited duration. BACKGROUND: The basic steps listed by...interest to perform the analysis outlined in steps 2 to 5, the prediction would only be reliable for up to a 3year return period. For a 5-year data set...for long-term hindcast data . The data retrieval and analysis program known as the Sea State Engineering Analysis System (SEAS) makes handling of the

System reliability, performance and trust in adaptable automation.

PubMed

Chavaillaz, Alain; Wastell, David; Sauer, Jürgen

2016-01-01

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

Reliability and agreement in student ratings of the class environment.