Reliability, Validity and Factor Structure of Drug Abuse Screening Test
Sayed Hadi Sayed Alitabar; Mojtaba Habibi; Maryam Falahatpisheh; Musa Arvin
2016-01-01
Background and Objective: According to the increasing of substance use in the country, more researches about this phenomenon are necessary. This Study Investigates the Validity, Reliability and Confirmatory Factor Structure of the Drug Abuse Screening test (DAST). Materials and Methods: The Sample Consisted of 381 Patients (143 Women and 238 Men) with a Multi-Stage Cluster Sampling of Areas 2, 6 and 12 of Tehran Were Selected from Each Region, 6 Randomly Selected Drug Rehabilitation Center. T...
Feelings about culture scales: development, factor structure, reliability, and validity.
Maffini, Cara S; Wong, Y Joel
2015-04-01
Although measures of cultural identity, values, and behavior exist in the multicultural psychological literature, there is currently no measure that explicitly assesses ethnic minority individuals' positive and negative affect toward culture. Therefore, we developed 2 new measures called the Feelings About Culture Scale--Ethnic Culture and Feelings About Culture Scale--Mainstream American Culture and tested their psychometric properties. In 6 studies, we piloted the measures, conducted factor analyses to clarify their factor structure, and examined reliability and validity. The factor structure revealed 2 dimensions reflecting positive and negative affect for each measure. Results provided evidence for convergent, discriminant, criterion-related, and incremental validity as well as the reliability of the scales. The Feelings About Culture Scales are the first known measures to examine both positive and negative affect toward an individual's ethnic culture and mainstream American culture. The focus on affect captures dimensions of psychological experiences that differ from cognitive and behavioral constructs often used to measure cultural orientation. These measures can serve as a valuable contribution to both research and counseling by providing insight into the nuanced affective experiences ethnic minority individuals have toward culture. (c) 2015 APA, all rights reserved).
Reliability, Validity and Factor Structure of Drug Abuse Screening Test
Directory of Open Access Journals (Sweden)
Sayed Hadi Sayed Alitabar
2016-05-01
Full Text Available Background and Objective: According to the increasing of substance use in the country, more researches about this phenomenon are necessary. This Study Investigates the Validity, Reliability and Confirmatory Factor Structure of the Drug Abuse Screening test (DAST. Materials and Methods: The Sample Consisted of 381 Patients (143 Women and 238 Men with a Multi-Stage Cluster Sampling of Areas 2, 6 and 12 of Tehran Were Selected from Each Region, 6 Randomly Selected Drug Rehabilitation Center. The DAST Was Used as Instrument. Divergent & Convergent Validity of this Scale Was Assessed with Problems Assessment for Substance Using Psychiatric Patients (PASUPP and Relapse Prediction Scale (RPS.Results: The DAST after the First Time Factor Structure of Using Confirmatory Factor Analysis Was Confirmed. The DAST Had a Good Internal Consistency (Cranach’s Alpha, and the Reliability of the Test Within a Week, 0.9, 0.8. Also this Scale Had a Positive Correlation with Problems Assessment for Substance Using Psychiatric Patients and Relapse Prediction Scale (P<0.01.Conclusion: The Overall Results Showed that the Drug Abuse Screening Test in Iranian Society Is Valid. It Can Be Said that Self-Report Scale Tool Is Useful for Research Purposes and Addiction.
Partial Safety Factors and Target Reliability Level in Danish Structural Codes
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Hansen, J. O.; Nielsen, T. A.
2001-01-01
The partial safety factors in the newly revised Danish structural codes have been derived using a reliability-based calibration. The calibrated partial safety factors result in the same average reliability level as in the previous codes, but a much more uniform reliability level has been obtained....... The paper describes the code format, the stochastic models and the resulting optimised partial safety factors....
Morales, Alexandra; Reis, Sibília; Espada, José P; Orgilés, Mireia
2016-09-01
The Short Health Anxiety Inventory is a brief instrument to assess health anxiety widely used across countries; however, no validated version is available for Portuguese-speaking population. Factorial structure, reliability, and equivalency factor with the Spanish version were analyzed with Portuguese adolescents aged 14-18 years. A Portuguese adolescent cohort ( N = 629) and a comparative Spanish adolescent cohort ( N = 1502) were evaluated. The original two-factor version was the best fitting model for the Portuguese version. The reliability was excellent. Complete measurement invariance across both countries was supported. The Portuguese version of the Short Health Anxiety Inventory is a valid screening inventory to assess health anxiety in adolescents.
Scale for positive aspects of caregiving experience: development, reliability, and factor structure.
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.
Systems reliability/structural reliability
International Nuclear Information System (INIS)
Green, A.E.
1980-01-01
The question of reliability technology using quantified techniques is considered for systems and structures. Systems reliability analysis has progressed to a viable and proven methodology whereas this has yet to be fully achieved for large scale structures. Structural loading variants over the half-time of the plant are considered to be more difficult to analyse than for systems, even though a relatively crude model may be a necessary starting point. Various reliability characteristics and environmental conditions are considered which enter this problem. The rare event situation is briefly mentioned together with aspects of proof testing and normal and upset loading conditions. (orig.)
Structural Reliability Methods
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Madsen, H. O.
The structural reliability methods quantitatively treat the uncertainty of predicting the behaviour and properties of a structure given the uncertain properties of its geometry, materials, and the actions it is supposed to withstand. This book addresses the probabilistic methods for evaluation...... of structural reliability, including the theoretical basis for these methods. Partial safety factor codes under current practice are briefly introduced and discussed. A probabilistic code format for obtaining a formal reliability evaluation system that catches the most essential features of the nature...... of the uncertainties and their interplay is the developed, step-by-step. The concepts presented are illustrated by numerous examples throughout the text....
Reliability-Based Calibration of Load Duration Factors for Timber Structures
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Svensson, Staffan; Stang, Birgitte Friis Dela
2005-01-01
John Dalsgaard Sørensen, Staffan Svensson, Birgitte Dela Stang : Reliability-Based Calibration of Load Duration Factors for Timber Structures Abstract : The load bearing capacity of timber structures decrease with time depending on the type of load and timber. Based on representative limit...... states and stochastic models for timber structures, load duration factors are calibrated using probabilistic methods. Load duration e.ects are estimated on basis of simulation of realizations of wind, snow and imposed loads in accordance with the load models in the Danish structural codes. Three damage...... accumulation models are considered, namely Gerhards model, Barrett and Foschi _ s model and Foschi and Yao _ s model. The parameters in these models are .tted by the Maximum Likelihood Method using data relevant for Danish structural timber and the statistical uncertainty is quanti .ed. The reliability...
The Study of Factor Structure and Reliability of an Abbreviated School Climate Survey
Ding, Cody; Liu, Ying; Berkowitz, Marvin
2011-01-01
The concept of school climate has been an important variable in research on quality of school life and student learning. One of the challenges in such a research effort is to develop instruments that could effectively and efficiently measure the construct. The purpose of the current study was to examine the factor structure and reliability of an…
International Nuclear Information System (INIS)
Han Bong Koo
1998-01-01
A reinforced concrete nuclear power plant containment structure is subjected to various random static and stochastic loads during its lifetime. Since these loads involve inherent randomness and other uncertainties, an appropriate probabilistic model for each load must be established in order to perform reliability analysis. The current ASME code for reinforced concrete containment structures are not based on probability concepts. The stochastic nature of natural hazard or accidental loads and the variations of material properties require a probabilistic approach for a rational assessment of structural safety and performance. The paper develops probability-based load factors for the limit state design of reinforced concrete containment structures. The purpose of constructing reinforced concrete containment structure is to protect against radioactive release, and so the use of a serviceability limit state against crack failure that can cause the emission of radioactive materials is suggested as a critical limit state for reinforced concrete containment structures. Load factors for the design of reinforced concrete containment structures are proposed and carried out the reliability assessments. (orig.)
Reliability Analysis and Calibration of Partial Safety Factors for Redundant Structures
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
1998-01-01
Redundancy is important to include in the design and analysis of structural systems. In most codes of practice redundancy is not directly taken into account. In the paper various definitions of a deterministic and reliability based redundancy measure are reviewed. It is described how reundancy can...... be included in the safety system and how partial safety factors can be calibrated. An example is presented illustrating how redundancy is taken into account in the safety system in e.g. the Danish codes. The example shows how partial safety factors can be calibrated to comply with the safety level...
Human factor reliability program
International Nuclear Information System (INIS)
Knoblochova, L.
2017-01-01
The human factor's reliability program was at Slovenske elektrarne, a.s. (SE) nuclear power plants. introduced as one of the components Initiatives of Excellent Performance in 2011. The initiative's goal was to increase the reliability of both people and facilities, in response to 3 major areas of improvement - Need for improvement of the results, Troubleshooting support, Supporting the achievement of the company's goals. The human agent's reliability program is in practice included: - Tools to prevent human error; - Managerial observation and coaching; - Human factor analysis; -Quick information about the event with a human agent; -Human reliability timeline and performance indicators; - Basic, periodic and extraordinary training in human factor reliability(authors)
Factor Structure, Validity and Reliability of the Revised Version of Skin Picking Scale
Directory of Open Access Journals (Sweden)
Mehdi Rabiei
2014-09-01
Full Text Available Background: The purpose of this study was to examine the factor structure, validity and reliability of the Skin Picking Scale-Revised Version. Materials and Methods: In this descriptive and validation study, participants were 550 (250 male and 300 female of the University of Isfahan were selected randomly from 15000 students. In order to examine the factor structure of the SPS-R we conducted both exploratory and confirmatory factor analyses and Cronbach's alpha. Results: Convergent validity of SPS-R with YBOCS-BDD, OCI-R and DASS 21-item were r=0.45, r=0.51 and r=0.70 (p<0.001. Exploratory and confirmatory factor analyses revealed two factors, one assessing impairment and the other symptom severity (4 items each. These factors could determine 58.1% of the variance. The Cronbach's alpha for the two factors were above 0.88. Also, results were shown to possess good psychometric properties, as well as discriminant validity and classification accuracy, in both clinical and community populations. Conclusion: It can be concluded that this instrument is a useful measure for assess skin-picking disorder symptoms in clinical assessment.
Lam, S S
2001-02-01
In 1990 Podsakoff, MacKenzie, Moorman, and Fetter developed a scale to measure the five dimensions of organizational citizenship behavior. Test-retest data over 15 weeks are reported for this scale for a sample of 82 female and 32 male Chinese tellers (ages 18 to 54 years) from a large international bank in Hong Kong. Stability was .83, and there was no significant change between Times 1 and 2. Analysis indicated the five-factor structure and showed it to be a reliable measure when used with a nonwestern sample.
The reasons for betel-quid chewing scale: assessment of factor structure, reliability, and validity.
Little, Melissa A; Pokhrel, Pallav; Murphy, Kelle L; Kawamoto, Crissy T; Suguitan, Gil S; Herzog, Thaddeus A
2014-06-03
Despite the fact that betel-quid is one of the most commonly used psychoactive substances worldwide and a major risk-factor for head-and-neck cancer incidence and mortality globally, currently no standardized instrument is available to assess the reasons why individuals chew betel-quid. A measure to assess reasons for chewing betel-quid could help researchers and clinicians develop prevention and treatment strategies. In the current study, we sought to develop and evaluate a self-report instrument for assessing the reasons for chewing betel quid which contributes toward the goal of developing effective interventions to reduce betel quid chewing in vulnerable populations. The current study assessed the factor structure, reliability and convergent validity of the Reasons for Betel-quid Chewing Scale (RBCS), a newly developed 10 item measure adapted from several existing "reasons for smoking" scales. The measure was administered to 351 adult betel-quid chewers in Guam. Confirmatory factor analysis of this measure revealed a three factor structure: reinforcement, social/cultural, and stimulation. Further tests revealed strong support for the internal consistency and convergent validity of this three factor measure. The goal of designing an intervention to reduce betel-quid chewing necessitates an understanding of why chewers chew; the current study makes considerable contributions towards that objective.
Directory of Open Access Journals (Sweden)
Khatuna Martsksvishvili
2017-12-01
Full Text Available The concept of emotional creativity is based on a social constructivist theory of emotion and refers to an individual’s ability to experience and express novel, sincere, and effective mixtures of emotions. The present research examines the psychometric properties of the Georgian version of Emotional Creativity Inventory (G-ECI; Averill, 1999. 834 individuals across five studies completed the G-ECI. Results from exploratory factor analysis indicate that the factor structure of the original ECI broadly replicates in the Georgian translation. The Cronbach’s alpha reliabilities of the G-ECI scales are mostly acceptable. There are significant gender differences. Examining the construct validity of G-ECI with other constructs (namely, with emotional intelligence, creativity and flow showed the expected relationships. In conclusion, the Georgian version of the emotional creativity inventory seems well suited for future research purposes.
Le, Minh Thi Hong; Tran, Thach Duc; Holton, Sara; Nguyen, Huong Thanh; Wolfe, Rory; Fisher, Jane
2017-01-01
To assess the internal consistency, latent structure and convergent validity of the Depression, Anxiety and Stress Scale-21 (DASS-21) among adolescents in Vietnam. An anonymous, self-completed questionnaire was conducted among 1,745 high school students in Hanoi, Vietnam between October, 2013 and January, 2014. Confirmatory factor analyses were performed to assess the latent structure of the DASS-21. Factorial invariance between girls and boys was examined. Cronbach alphas and correlation coefficients between DASS-21 factor scores and the domain scores of the Duke Health Profile Adolescent Vietnamese validated version (ADHP-V) were calculated to assess DASS-21 internal consistency and convergent validity. A total of 1,606/ 1,745 (92.6%) students returned the questionnaire. Of those, 1,387 students provided complete DASS-21 data. The scale demonstrated adequate internal consistency (Cronbach α: 0.761 to 0.906). A four-factor model showed the best fit to the data. Items loaded significantly on a common general distress factor, the depression, and the anxiety factors, but few on the stress factor (pDASS-21 convergent validity was confirmed with moderate correlation coefficients (-0.47 to -0.66) between its factor scores and the ADHP-V mental health related domains. The DASS-21 is reliable and suitable for use to assess symptoms of common mental health problems, especially depression and anxiety among Vietnamese adolescents. However, its ability in detecting stress among these adolescents may be limited. Further research is warrant to explore these results.
Directory of Open Access Journals (Sweden)
Minh Thi Hong Le
Full Text Available To assess the internal consistency, latent structure and convergent validity of the Depression, Anxiety and Stress Scale-21 (DASS-21 among adolescents in Vietnam.An anonymous, self-completed questionnaire was conducted among 1,745 high school students in Hanoi, Vietnam between October, 2013 and January, 2014. Confirmatory factor analyses were performed to assess the latent structure of the DASS-21. Factorial invariance between girls and boys was examined. Cronbach alphas and correlation coefficients between DASS-21 factor scores and the domain scores of the Duke Health Profile Adolescent Vietnamese validated version (ADHP-V were calculated to assess DASS-21 internal consistency and convergent validity.A total of 1,606/ 1,745 (92.6% students returned the questionnaire. Of those, 1,387 students provided complete DASS-21 data. The scale demonstrated adequate internal consistency (Cronbach α: 0.761 to 0.906. A four-factor model showed the best fit to the data. Items loaded significantly on a common general distress factor, the depression, and the anxiety factors, but few on the stress factor (p<0.05. DASS-21 convergent validity was confirmed with moderate correlation coefficients (-0.47 to -0.66 between its factor scores and the ADHP-V mental health related domains.The DASS-21 is reliable and suitable for use to assess symptoms of common mental health problems, especially depression and anxiety among Vietnamese adolescents. However, its ability in detecting stress among these adolescents may be limited. Further research is warrant to explore these results.
Directory of Open Access Journals (Sweden)
Oscar Armando Esparza-Del Villar
2017-03-01
Full Text Available Abstract Background Mexico is one of the countries with the highest rates of overweight and obesity around the world, with 68.8% of men and 73% of women reporting both. This is a public health problem since there are several health related consequences of not exercising, like having cardiovascular diseases or some types of cancers. All of these problems can be prevented by promoting exercise, so it is important to evaluate models of health behaviors to achieve this goal. Among several models the Health Belief Model is one of the most studied models to promote health related behaviors. This study validates the first exercise scale based on the Health Belief Model (HBM in Mexicans with the objective of studying and analyzing this model in Mexico. Methods Items for the scale called the Exercise Health Belief Model Scale (EHBMS were developed by a health research team, then the items were applied to a sample of 746 participants, male and female, from five cities in Mexico. The factor structure of the items was analyzed with an exploratory factor analysis and the internal reliability with Cronbach’s alpha. Results The exploratory factor analysis reported the expected factor structure based in the HBM. The KMO index (0.92 and the Barlett’s sphericity test (p < 0.01 indicated an adequate and normally distributed sample. Items had adequate factor loadings, ranging from 0.31 to 0.92, and the internal consistencies of the factors were also acceptable, with alpha values ranging from 0.67 to 0.91. Conclusions The EHBMS is a validated scale that can be used to measure exercise based on the HBM in Mexican populations.
The Factor Structure and Composite Reliability of the Rosenberg Self-Esteem Scale among Ex-Prisoners
Boduszek, Daniel; Hyland, Philip; Dhingra, Katie; Mallett, John
2013-01-01
The aim of this study was to examine the factor structure and composite reliability of the\\ud Rosenberg Self-Esteem Scale (RSES) using a sample of 669 ex-prisoners identified in the National Survey of American Life. Six distinct factor models, with uncorrelated measurement error terms, were specified and tested using confirmatory factor analysis (CFA). Results indicated that the two-factor model consisting of positive and negative latent variables provided a better fit to the data than the al...
Reliability and factor structure of the audit among male and female ...
African Journals Online (AJOL)
We assessed the reliability and dimensional structure of the Alcohol Use Disorders Identification Test (AUDIT) among bar patrons in a rural area of South Africa. In total, 406 bar patrons completed a questionnaire containing the AUDIT, and demographic and psychosocial measures. The participants consisted of 314 (77.3%) ...
Czech Academy of Sciences Publication Activity Database
Marek, Pavel; Guštar, M.; Permaul, K.
1999-01-01
Roč. 14, č. 1 (1999), s. 105-118 ISSN 0266-8920 R&D Projects: GA ČR GA103/94/0562; GA ČR GV103/96/K034 Keywords : reliability * safety * failure * durability * Monte Carlo method Subject RIV: JM - Building Engineering Impact factor: 0.522, year: 1999
Factor Structure and Reliability of Test Items for Saudi Teacher Licence Assessment
Alsadaawi, Abdullah Saleh
2017-01-01
The Saudi National Assessment Centre administers the Computer Science Teacher Test for teacher certification. The aim of this study is to explore gender differences in candidates' scores, and investigate dimensionality, reliability, and differential item functioning using confirmatory factor analysis and item response theory. The confirmatory…
Structural systems reliability analysis
International Nuclear Information System (INIS)
Frangopol, D.
1975-01-01
For an exact evaluation of the reliability of a structure it appears necessary to determine the distribution densities of the loads and resistances and to calculate the correlation coefficients between loads and between resistances. These statistical characteristics can be obtained only on the basis of a long activity period. In case that such studies are missing the statistical properties formulated here give upper and lower bounds of the reliability. (orig./HP) [de
Reliability Based Ship Structural Design
DEFF Research Database (Denmark)
Dogliani, M.; Østergaard, C.; Parmentier, G.
1996-01-01
This paper deals with the development of different methods that allow the reliability-based design of ship structures to be transferred from the area of research to the systematic application in current design. It summarises the achievements of a three-year collaborative research project dealing...... with developments of models of load effects and of structural collapse adopted in reliability formulations which aim at calibrating partial safety factors for ship structural design. New probabilistic models of still-water load effects are developed both for tankers and for containerships. New results are presented...... structure of several tankers and containerships. The results of the reliability analysis were the basis for the definition of a target safety level which was used to asses the partial safety factors suitable for in a new design rules format to be adopted in modern ship structural design. Finally...
Jacobs, Karen; Struyf, Elke
2013-01-01
Socioemotional guidance of students has recently become an integral part of education, however no instrument exists to measure integrated socioemotional guidance. This study therefore examines the factor structure and reliability of the Socioemotional Guidance Questionnaire. Psychometric properties of the Socioemotional Guidance Questionnaire and…
Reliability based structural design
Vrouwenvelder, A.C.W.M.
2014-01-01
According to ISO 2394, structures shall be designed, constructed and maintained in such a way that they are suited for their use during the design working life in an economic way. To fulfil this requirement one needs insight into the risk and reliability under expected and non-expected actions. A
Maroufizadeh, Saman; Omani Samani, Reza; Amini, Payam; Navid, Behnaz
2016-09-01
This study examined psychometric properties of the Levenson's Locus of Control Scale among Iranian infertile patients. In all, 312 infertile patients completed the Levenson's Locus of Control Scale and Hospital Anxiety and Depression Scale. The confirmatory factor analysis indicated that the original three-factor model of Levenson's Locus of Control Scale was adequate ( χ 2 / df = 2.139; goodness-of-fit index = 0.88; root mean square error of approximation = 0.061; and standardized root mean square residual = 0.076). The Cronbach's alpha of the subscales ranged from 0.56 to 0.67. The Levenson's Locus of Control Scale subscales significantly correlated with anxiety and depression, showing an acceptable convergent validity. In conclusion, the Levenson's Locus of Control Scale has adequate reliability and validity and can be used to measure locus of control orientation in Iranian infertile patients.
Delaware School Climate Survey--Student: Its Factor Structure, Concurrent Validity, and Reliability
Bear, George G.; Gaskins, Clare; Blank, Jessica; Chen, Fang Fang
2011-01-01
The Delaware School Climate Survey-Student (DSCS-S) was developed to provide schools with a brief and psychometrically sound student survey for assessing school climate, particularly the dimensions of social support and structure. Confirmatory factor analyses, conducted on a sample of 11,780 students in 85 schools, showed that a bifactor model…
Reliability of the factor structure of the Multidimensional Scale of Interpersonal Reactivity (EMRI
Directory of Open Access Journals (Sweden)
Nilton S. Formiga
2013-10-01
Full Text Available This study aims to check the internal consistency and factor structure evaluative of the empathy scale in a high school and college sample in the state of Minas Gerais. The instruments that measure empathy can be easily found, however, of the existing, just multidimensional scale of interpersonal reactivity (Emri is the theoretical framework that has far more and better organized, and the scale that is most commonly used to assess this construct. Participated 488 subjects, male and female, with ages from 14-54 years old, distributed in primary and college levels in Patrocínio-MG composed this study sample. The subjects answered the Multidimensional Scale of Interpersonal Reactivity and socio-demographic data. From an equation analysis and structural modeling were observed psychometric indicators that assured the structural consistency of the scale, promoting in the security of the measure theoretical construct of empathy.
Power peaking nuclear reliability factors
International Nuclear Information System (INIS)
Hassan, H.A.; Pegram, J.W.; Mays, C.W.; Romano, J.J.; Woods, J.J.; Warren, H.D.
1977-11-01
The Calculational Nuclear Reliability Factor (CNRF) assigned to the limiting power density calculated in reactor design has been determined. The CNRF is presented as a function of the relative power density of the fuel assembly and its radial local. In addition, the Measurement Nuclear Reliability Factor (MNRF) for the measured peak hot pellet power in the core has been evaluated. This MNRF is also presented as a function of the relative power density and radial local within the fuel assembly
Ren, Zhengjia; Hood, Ralph W
2018-04-01
This study reports the development of an inventory to assess the perceived internalized homophobia of gay men in a collectivistic Chinese cultural context. The results of exploratory and confirmatory factor analyses using two samples suggested the viability and stability of a three-factor model: internalized heteronormativity (IHN), family-oriented identity (FOI), and socially oriented identity (SOI). The 11-item internalized homophobia inventory demonstrated good internal consistency and construct validity. Internalized homophobia was related positively to the extent of a sense of loneliness and negatively to self-evaluation and the discrepancy in self-identification as a gay man. In addition, the participants' internalized SOI consistently predicted their coming out choices in their social surroundings, while their FOI predicted their decisions to enter into heterosexual marriages. The findings suggest that sexual self-prejudice was correlated with IHN, family values, and social norms. The present research demonstrates that a culturally sensitive scale is necessary to understand the cultural and family-oriented values that influence gay Chinese men's everyday lives, self-constructs, and behavioral choices.
Forde, David R; Baron, Stephen W; Scher, Christine D; Stein, Murray B
2012-01-01
This study examines the psychometric properties of the Childhood Trauma Questionnaire short form (CTQ-SF) with street youth who have run away or been expelled from their homes (N = 397). Internal reliability coefficients for the five clinical scales ranged from .65 to .95. Confirmatory Factor Analysis (CFA) was used to test the five-factor structure of the scales yielding acceptable fit for the total sample. Additional multigroup analyses were performed to consider items by gender. Results provided only evidence of weak factorial invariance. Constrained models showed invariance in configuration, factor loadings, and factor covariances but failed for equality of intercepts. Mean trauma scores for street youth tended to fall in the moderate to severe range on all abuse/neglect clinical scales. Females reported higher levels of abuse and neglect. Prevalence of child maltreatment of individual forms was very high with 98% of street youth reporting one or more forms; 27.4% of males and 48.9% of females reported all five forms. Results of this study support the viability of the CTQ-SF for screening maltreatment in a highly vulnerable street population. Caution is recommended when comparing prevalence estimates for male and female street youth given the failure of the strong factorial multigroup model.
Structural Optimization with Reliability Constraints
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Thoft-Christensen, Palle
1986-01-01
During the last 25 years considerable progress has been made in the fields of structural optimization and structural reliability theory. In classical deterministic structural optimization all variables are assumed to be deterministic. Due to the unpredictability of loads and strengths of actual......]. In this paper we consider only structures which can be modelled as systems of elasto-plastic elements, e.g. frame and truss structures. In section 2 a method to evaluate the reliability of such structural systems is presented. Based on a probabilistic point of view a modern structural optimization problem...... is formulated in section 3. The formulation is a natural extension of the commonly used formulations in determinstic structural optimization. The mathematical form of the optimization problem is briefly discussed. In section 4 two new optimization procedures especially designed for the reliability...
Huang, Francis L.; Cornell, Dewey G.
2016-01-01
Although school climate has long been recognized as an important factor in the school improvement process, there are few psychometrically supported measures based on teacher perspectives. The current study replicated and extended the factor structure, concurrent validity, and test-retest reliability of the teacher version of the Authoritative…
Reliability-Based Optimization in Structural Engineering
DEFF Research Database (Denmark)
Enevoldsen, I.; Sørensen, John Dalsgaard
1994-01-01
In this paper reliability-based optimization problems in structural engineering are formulated on the basis of the classical decision theory. Several formulations are presented: Reliability-based optimal design of structural systems with component or systems reliability constraints, reliability...
Structural Reliability of Wind Turbine Blades
DEFF Research Database (Denmark)
Dimitrov, Nikolay Krasimirov
turbine blades. The main purpose is to draw a clear picture of how reliability-based design of wind turbines can be done in practice. The objectives of the thesis are to create methodologies for efficient reliability assessment of composite materials and composite wind turbine blades, and to map...... the uncertainties in the processes, materials and external conditions that have an effect on the health of a composite structure. The study considers all stages in a reliability analysis, from defining models of structural components to obtaining the reliability index and calibration of partial safety factors...... by developing new models and standards or carrying out tests The following aspects are covered in detail: ⋅ The probabilistic aspects of ultimate strength of composite laminates are addressed. Laminated plates are considered as a general structural reliability system where each layer in a laminate is a separate...
System Reliability of Timber Structures
DEFF Research Database (Denmark)
Kirkegaard, Poul Henning; Sørensen, John Dalsgaard
2010-01-01
elements, alternate load path(s) etc. in the structural design. In general these characteristics can have a positive influence on system reliability of a structure however, in Eurocodes ductility is only awarded for concrete and steel structures but not for timber structures. It is well......-know that structural systems can redistribute internal forces due to ductility of a connection, i.e. some additional loads can be carried by the structure. The same effect is also possible for reinforced concrete structures and structures of steel. However, for timber structures codes do not award that ductility......For reduction of the risk of collapse in the event of loss of structural element(s), a structural engineer may take necessary steps to design a collapse-resistant structure that is insensitive to accidental circumstances e.g. by incorporating characteristics like redundancy, ties, ductility, key...
Evaluation of structural reliability using simulation methods
Directory of Open Access Journals (Sweden)
Baballëku Markel
2015-01-01
Full Text Available Eurocode describes the 'index of reliability' as a measure of structural reliability, related to the 'probability of failure'. This paper is focused on the assessment of this index for a reinforced concrete bridge pier. It is rare to explicitly use reliability concepts for design of structures, but the problems of structural engineering are better known through them. Some of the main methods for the estimation of the probability of failure are the exact analytical integration, numerical integration, approximate analytical methods and simulation methods. Monte Carlo Simulation is used in this paper, because it offers a very good tool for the estimation of probability in multivariate functions. Complicated probability and statistics problems are solved through computer aided simulations of a large number of tests. The procedures of structural reliability assessment for the bridge pier and the comparison with the partial factor method of the Eurocodes have been demonstrated in this paper.
Human factors reliability Benchmark exercise
International Nuclear Information System (INIS)
Poucet, A.
1989-06-01
The Joint Research Centre of the European Commission has organized a Human Factors Reliability Benchmark Exercise (HF-RBE) with the aim of assessing the state of the art in human reliability modelling and assessment. Fifteen teams from eleven countries, representing industry, utilities, licensing organisations and research institutes, participated in the HF-RBE. The HF-RBE was organized around two study cases: (1) analysis of routine functional Test and Maintenance (T and M) procedures: with the aim of assessing the probability of test induced failures, the probability of failures to remain unrevealed and the potential to initiate transients because of errors performed in the test; (2) analysis of human actions during an operational transient: with the aim of assessing the probability that the operators will correctly diagnose the malfunctions and take proper corrective action. This report contains the final summary reports produced by the participants in the exercise
Bitsika, Vicki; Sharpley, Christopher F.
2018-01-01
The validity, reliability and factor structure of the Autism Spectrum Disorder Behaviour Checklist-Revised (ASDBC-R) were measured in a sample of 140 boys with Autism Spectrum Disorder (ASD) aged between 6 and 18 years. Internal consistency (Cronbach's alpha) was satisfactory and the ASDBC-R significantly correlated with the Social Responsiveness…
Human factors reliability benchmark exercise
International Nuclear Information System (INIS)
Poucet, A.
1989-08-01
The Joint Research Centre of the European Commission has organised a Human Factors Reliability Benchmark Exercise (HF-RBE) with the aim of assessing the state of the art in human reliability modelling and assessment. Fifteen teams from eleven countries, representing industry, utilities, licensing organisations and research institutes, participated in the HF-RBE. The HF-RBE was organised around two study cases: (1) analysis of routine functional Test and Maintenance (TPM) procedures: with the aim of assessing the probability of test induced failures, the probability of failures to remain unrevealed and the potential to initiate transients because of errors performed in the test; (2) analysis of human actions during an operational transient: with the aim of assessing the probability that the operators will correctly diagnose the malfunctions and take proper corrective action. This report summarises the contributions received from the participants and analyses these contributions on a comparative basis. The aim of this analysis was to compare the procedures, modelling techniques and quantification methods used, to obtain insight in the causes and magnitude of the variability observed in the results, to try to identify preferred human reliability assessment approaches and to get an understanding of the current state of the art in the field identifying the limitations that are still inherent to the different approaches
Kolokotroni, Philippa; Anagnostopoulos, Fotios; Missitzis, Ioannis
2017-07-01
The study and measurement of psychosocial adjustment is important for evaluating patients' well-being, and assessing the illness's course, treatment's success, and patients' recovery. In this study, internal consistency reliability and construct validity of the Greek version of the Psychosocial Adjustment to Illness Scale-Self-Report (PAIS-SR) were examined. Demographic and psychosocial data were collected from a sample of 243 women with breast cancer, recruited from September 2011 to December 2012. With some exceptions in specific items, the original conceptually-derived PAIS-SR subscales emerged in a seven-factor solution. Social Environment, Job and Household Duties, and Psychological Distress accounted for more of the total variance than other subscales. PAIS-SR showed good internal consistency reliability, with Cronbach's alpha coefficients >0.62. Correlations of PAIS-SR domains with measures of quality of life and posttraumatic stress symptoms supported the convergent validity of the PAIS-SR and its significance for cancer research. The Greek version of the PAIS-SR has acceptable internal consistency reliability and construct validity, as well as satisfactory convergent validity. Results provide some suggestions for the development of programs to evaluate adjustment status and implement psychosocial interventions among breast cancer survivors.
On the NPP structural reliability
International Nuclear Information System (INIS)
Klemin, A.I.; Polyakov, E.F.
1980-01-01
Reviewed are the main statements peculiarities and possibilities of the first branch guiding technical material (GTM) ''The methods of calculation of structural reliability of NPP and its systems at the stage of projecting''. It is stated, that in GTM presented are recomendations on the calculation of reliability of such specific systems, as the system of the reactor control and protection the system of measuring instruments and automatics and safe systems. GTM are based on analytical methods of modern theory of realibility with the Use of metodology of minimal cross sections of complex systems. It is stressed, that the calculations on the proposed methods permit to calculate a wide complex of reliability parameters, reflecting separately or together prorerties of NPP dependability and maintainability. For NPP, operating by a variable schedule of leading, aditionally considered are parameters, characterizing reliability with account of the proposed regime of power change, i.e. taking into account failures, caused by decrease of the obtained power lower, than the reguired or increase of the required power higher, than the obtained
Structural reliability assessment capability in NESSUS
Millwater, H.; Wu, Y.-T.
1992-07-01
The principal capabilities of NESSUS (Numerical Evaluation of Stochastic Structures Under Stress), an advanced computer code developed for probabilistic structural response analysis, are reviewed, and its structural reliability assessed. The code combines flexible structural modeling tools with advanced probabilistic algorithms in order to compute probabilistic structural response and resistance, component reliability and risk, and system reliability and risk. An illustrative numerical example is presented.
Directory of Open Access Journals (Sweden)
Nafiseh Tabatabaei
2016-08-01
Full Text Available Background and Objectives: Researches on attention deficit and hyperactivity disorder indicated that this common disorder would not be resolved with age and continues into adulthood. This study was carried out with the objective of validation and normalization of diagnostic scale of adult attention deficit/hyperactivity disorder scale in Iranian sample. Methods: This study was performed as a psychometric study on the patients (1400 to 1600 cases referred to two psychiatry and neurology clinics in Tehran in the autumn and winter of 2014. Among these patients, 301 persons were selected by purposeful non-random sampling according to the sample size formula based on ratio or two-value variable (patient and non-patient and related questionnaire was administered to them. Cronbach's alpha, Spearman- Brown, and Guttmann’s coefficients was used to evaluate concurrent validity and reliability and exploratory and confirmatory factor analysis in order to assess the construct validity. Results: In this study, Cronbach's alpha of the total scale was 0.88 and for the subscales of inattention, hyperactivity, and impulsivity were 0.82, 0.72, 0.67, respectively. The correlation coefficients between the mentioned scale and adult attention deficit/hyperactivity questionnaire (Wender Utah was obtained 0.59, and between the subscales and the Wender Utah questionnaire, were 0.56, 0.49, and 0.40, respectively, which all three were significant (p<0/01. Confirmatory factor analysis results showed that this scale has three factors and two goodness-of-fit indices. Conclusion: The results of this study revealed that specialists can diagnose and treat the patients using this diagnostic scale.
System reliability developments in structural engineering
International Nuclear Information System (INIS)
Moses, F.
1982-01-01
Two major limitations occur in present structural design code developments utilizing reliability theory. The notional system reliabilities may differ significantly from calibrated component reliabilities. Secondly, actual failures are often due to gross errors not reflected in most present code formats. A review is presented of system reliability methods and further new concepts are developed. The incremental load approach for identifying and expressing collapse modes is expanded by employing a strategy to identify and enumerate the significant structural collapse modes. It further isolates the importance of critical components in the system performance. Ductile and brittle component behavior and strength correlation is reflected in the system model and illustrated in several examples. Modal combinations for the system reliability are also reviewed. From these developments a system factor can be addended to component safety checking equations. Values may be derived from system behavior by substituting in a damage model which accounts for the response range from component failure to collapse. Other strategies are discussed which emphasize quality assurance during design and in-service inspection for components whose behavior is critical to the system reliability. (Auth.)
Karimi, Fatemeh Zahra; Alesheikh, Aytay; Pakravan, Soheila; Abdollahi, Mahbubeh; Damough, Mozhdeh; Anbaran, Zahra Khosravi; Farahani, Leila Amiri
2017-10-01
In medical sciences, commitment to lifelong learning has been expressed as an important element. Today, due to the rapid development of medical information and technology, lifelong learning is critical for safe medical care and development in medical research. JeffSPLL is one of the scales for measuring lifelong learning among the staff of medical sciences that has never been used in Iran. The aim of the present study was to determine the factor structure and reliability of the Persian version of JeffSPLL among Persian-speaking staff of universities of medical sciences in Iran. This study was a cross-sectional study, methodologically, that was conducted in 2012-2013. In this study, 210 staff members of Birjand University of Medical Sciences were selected. Data collection tool was the Persian version of JeffSPLL. To investigate the factor structure of this tool, confirmatory factor analysis was used and to evaluate the model fit, goodness-of-fit indices, root mean square error of approximation (RMSEA), the ratio of chi-square to the degree of freedom associated with it, comparative fit index (CFI), and root mean square residual (RMR) were used. To investigate the reliability of tool, Cronbach's alpha was employed. Data analysis was conducted using LISREL8.8 and SPSS 20 software. Confirmatory factor analysis showed that RMSEA was close to 0.1, and CFI and GFI were close to one. Therefore, four-factor model was appropriate. Cronbach's alpha was 0.92 for the whole tool and it was between 0.82 and 0.89 for subscales. The present study verified the four-factor structure of the 19-item Persian version of JeffSPLL that included professional learning beliefs and motivation, scholarly activities, attention to learning opportunities, and technical skills in information seeking among the staff. In addition, this tool has acceptable reliability. Therefore, it was appropriate to assess lifelong learning in the Persian-speaking staff population.
Hoben, Matthias; Estabrooks, Carole A.; Squires, Janet E.; Behrens, Johann
2016-01-01
We translated the Canadian residential long term care versions of the Alberta Context Tool (ACT) and the Conceptual Research Utilization (CRU) Scale into German, to study the association between organizational context factors and research utilization in German nursing homes. The rigorous translation process was based on best practice guidelines for tool translation, and we previously published methods and results of this process in two papers. Both instruments are self-report questionnaires used with care providers working in nursing homes. The aim of this study was to assess the factor structure, reliability, and measurement invariance (MI) between care provider groups responding to these instruments. In a stratified random sample of 38 nursing homes in one German region (Metropolregion Rhein-Neckar), we collected questionnaires from 273 care aides, 196 regulated nurses, 152 allied health providers, 6 quality improvement specialists, 129 clinical leaders, and 65 nursing students. The factor structure was assessed using confirmatory factor models. The first model included all 10 ACT concepts. We also decided a priori to run two separate models for the scale-based and the count-based ACT concepts as suggested by the instrument developers. The fourth model included the five CRU Scale items. Reliability scores were calculated based on the parameters of the best-fitting factor models. Multiple-group confirmatory factor models were used to assess MI between provider groups. Rather than the hypothesized ten-factor structure of the ACT, confirmatory factor models suggested 13 factors. The one-factor solution of the CRU Scale was confirmed. The reliability was acceptable (>0.7 in the entire sample and in all provider groups) for 10 of 13 ACT concepts, and high (0.90–0.96) for the CRU Scale. We could demonstrate partial strong MI for both ACT models and partial strict MI for the CRU Scale. Our results suggest that the scores of the German ACT and the CRU Scale for nursing
Directory of Open Access Journals (Sweden)
Yukiko Ohashi
2016-08-01
Full Text Available Negative attitudes of mothers towards their infant is conceptualized as postpartum bonding disorder, which leads to serious health problems in perinatal health care. However, its measurement still remains to be standardized. Our aim was to examine and confirm the psychometric properties of the Postnatal Bonding Questionnaire (PBQ in Japanese mothers. We distributed a set of questionnaires to community mothers and studied 392 mothers who returned the questionnaires at 1 month after childbirth. Our model was compared with three other models derived from previous studies. In a randomly halved sample, an exploratory factor analysis yielded a three-factor structure: Anger and Restrictedness, Lack of Affection, and Rejection and Fear. This factor structure was cross-validated by a confirmatory factor analysis using the other halved sample. The three subscales showed satisfactory internal consistency. The three PBQ subscale scores were correlated with depression and psychological abuse scores. Their test–retest reliability between day 5 and 1 month after childbirth was measured by intraclass correlation coefficients between 0.76 and 0.83. The Akaike Information Criteria of our model was better than the original four-factor model of Brockington. The present study indicates that the PBQ is a reliable and valid measure of bonding difficulties of Japanese mothers with neonates.
Brunault, Paul; Ballon, Nicolas; Gaillard, Philippe; Réveillère, Christian; Courtois, Robert
2014-05-01
The concept of food addiction has recently been proposed by applying the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria for substance dependence to eating behaviour. Food addiction has received increased attention given that it may play a role in binge eating, eating disorders, and the recent increase in obesity prevalence. Currently, there is no psychometrically sound tool for assessing food addiction in French. Our study aimed to test the psychometric properties of a French version of the Yale Food Addiction Scale (YFAS) by establishing its factor structure and construct validity in a nonclinical population. A total of 553 participants were assessed for food addiction (French version of the YFAS) and binge eating behaviour (Bulimic Investigatory Test Edinburgh and Binge Eating Scale). We tested the scale's factor structure (factor analysis for dichotomous data based on tetrachoric correlation coefficients), internal consistency, and construct validity with measures of binge eating. Our results supported a 1-factor structure, which accounted for 54.1% of the variance. This tool had adequate reliability and high construct validity with measures of binge eating in this population, both in its diagnosis and symptom count version. A 2-factor structure explained an additional 9.1% of the variance, and could differentiate between patients with high, compared with low, levels of insight regarding addiction symptoms. In our study, we validated a psychometrically sound French version of the YFAS, both in its symptom count and diagnostic version. Future studies should validate this tool in clinical samples.
Matulis, Simone; Loos, Laura; Langguth, Nadine; Schreiber, Franziska; Gutermann, Jana; Gawrilow, Caterina; Steil, Regina
2015-01-01
Background The Trauma Symptom Checklist for Children (TSC-C) is the most widely used self-report scale to assess trauma-related symptoms in children and adolescents on six clinical scales. The purpose of the present study was to develop a German version of the TSC-C and to investigate its psychometric properties, such as factor structure, reliability, and validity, in a sample of German adolescents. Method A normative sample of N=583 and a clinical sample of N=41 adolescents with a history of physical or sexual abuse aged between 13 and 21 years participated in the study. Results The Confirmatory Factor Analysis on the six-factor model (anger, anxiety, depression, dissociation, posttraumatic stress, and sexual concerns with the subdimensions preoccupation and distress) revealed acceptable to good fit statistics in the normative sample. One item had to be excluded from the German version of the TSC-C because the factor loading was too low. All clinical scales presented acceptable to good reliability, with Cronbach's α's ranging from .80 to .86 in the normative sample and from .72 to .87 in the clinical sample. Concurrent validity was also demonstrated by the high correlations between the TSC-C scales and instruments measuring similar psychopathology. TSC-C scores reliably differentiated between adolescents with trauma history and those without trauma history, indicating discriminative validity. Conclusions In conclusion, the German version of the TSC-C is a reliable and valid instrument for assessing trauma-related symptoms on six different scales in adolescents aged between 13 and 21 years. PMID:26498182
Dependent systems reliability estimation by structural reliability approach
DEFF Research Database (Denmark)
Kostandyan, Erik; Sørensen, John Dalsgaard
2014-01-01
Estimation of system reliability by classical system reliability methods generally assumes that the components are statistically independent, thus limiting its applicability in many practical situations. A method is proposed for estimation of the system reliability with dependent components, where...... the leading failure mechanism(s) is described by physics of failure model(s). The proposed method is based on structural reliability techniques and accounts for both statistical and failure effect correlations. It is assumed that failure of any component is due to increasing damage (fatigue phenomena...... identification. Application of the proposed method can be found in many real world systems....
Chin, Weng Yee; Choi, Edmond P H; Chan, Kit T Y; Wong, Carlos K H
2015-01-01
The Center for Epidemiologic Studies Depression Scale (CES-D) is a commonly used instrument to measure depressive symptomatology. Despite this, the evidence for its psychometric properties remains poorly established in Chinese populations. The aim of this study was to validate the use of the CES-D in Chinese primary care patients by examining factor structure, construct validity, reliability, sensitivity and responsiveness. The psychometric properties were assessed amongst a sample of 3686 Chinese adult primary care patients in Hong Kong. Three competing factor structure models were examined using confirmatory factor analysis. The original CES-D four-structure model had adequate fit, however the data was better fit into a bi-factor model. For the internal construct validity, corrected item-total correlations were 0.4 for most items. The convergent validity was assessed by examining the correlations between the CES-D, the Patient Health Questionnaire 9 (PHQ-9) and the Short Form-12 Health Survey (version 2) Mental Component Summary (SF-12 v2 MCS). The CES-D had a strong correlation with the PHQ-9 (coefficient: 0.78) and SF-12 v2 MCS (coefficient: -0.75). Internal consistency was assessed by McDonald's omega hierarchical (ωH). The ωH value for the general depression factor was 0.855. The ωH values for "somatic", "depressed affect", "positive affect" and "interpersonal problems" were 0.434, 0.038, 0.738 and 0.730, respectively. For the two-week test-retest reliability, the intraclass correlation coefficient was 0.91. The CES-D was sensitive in detecting differences between known groups, with the AUC >0.7. Internal responsiveness of the CES-D to detect positive and negative changes was satisfactory (with p value 0.2). The CES-D was externally responsive, with the AUC>0.7. The CES-D appears to be a valid, reliable, sensitive and responsive instrument for screening and monitoring depressive symptoms in adult Chinese primary care patients. In its original four-factor
Directory of Open Access Journals (Sweden)
Weng Yee Chin
Full Text Available The Center for Epidemiologic Studies Depression Scale (CES-D is a commonly used instrument to measure depressive symptomatology. Despite this, the evidence for its psychometric properties remains poorly established in Chinese populations. The aim of this study was to validate the use of the CES-D in Chinese primary care patients by examining factor structure, construct validity, reliability, sensitivity and responsiveness.The psychometric properties were assessed amongst a sample of 3686 Chinese adult primary care patients in Hong Kong. Three competing factor structure models were examined using confirmatory factor analysis. The original CES-D four-structure model had adequate fit, however the data was better fit into a bi-factor model. For the internal construct validity, corrected item-total correlations were 0.4 for most items. The convergent validity was assessed by examining the correlations between the CES-D, the Patient Health Questionnaire 9 (PHQ-9 and the Short Form-12 Health Survey (version 2 Mental Component Summary (SF-12 v2 MCS. The CES-D had a strong correlation with the PHQ-9 (coefficient: 0.78 and SF-12 v2 MCS (coefficient: -0.75. Internal consistency was assessed by McDonald's omega hierarchical (ωH. The ωH value for the general depression factor was 0.855. The ωH values for "somatic", "depressed affect", "positive affect" and "interpersonal problems" were 0.434, 0.038, 0.738 and 0.730, respectively. For the two-week test-retest reliability, the intraclass correlation coefficient was 0.91. The CES-D was sensitive in detecting differences between known groups, with the AUC >0.7. Internal responsiveness of the CES-D to detect positive and negative changes was satisfactory (with p value 0.2. The CES-D was externally responsive, with the AUC>0.7.The CES-D appears to be a valid, reliable, sensitive and responsive instrument for screening and monitoring depressive symptoms in adult Chinese primary care patients. In its original
Reliability and optimization of structural systems
International Nuclear Information System (INIS)
Thoft-Christensen, P.
1987-01-01
The proceedings contain 28 papers presented at the 1st working conference. The working conference was organized by the IFIP Working Group 7.5. The proceedings also include 4 papers which were submitted, but for various reasons not presented at the working conference. The working conference was attended by 50 participants from 18 countries. The conference was the first scientific meeting of the new IFIP Working Group 7.5 on 'Reliability and Optimization of Structural Systems'. The purpose of the Working Group 7.5 is to promote modern structural system optimization and reliability theory, to advance international cooperation in the field of structural system optimization and reliability theory, to stimulate research, development and application of structural system optimization and reliability theory, to further the dissemination and exchange of information on reliability and optimization of structural system optimization and reliability theory, and to encourage education in structural system optimization and reliability theory. (orig./HP)
Thimm, Jens C
2017-12-01
The Computerized Adaptive Test of Personality Disorder-Static Form (CAT-PD-SF) is a self-report inventory developed to assess pathological personality traits. The current study explored the reliability and higher order factor structure of the Norwegian version of the CAT-PD-SF and the relationships between the CAT-PD traits and domains of personality functioning in an undergraduate student sample ( N = 375). In addition to the CAT-PD-SF, the short form of the Severity Indices of Personality Problems and the Brief Symptom Inventory were administered. The results showed that the Norwegian CAT-PD-SF has good score reliability. Factor analysis of the CAT-PD-SF scales indicated five superordinate factors that correspond to the trait domains of the alternative DSM-5 model for personality disorders. The CAT-PD traits were highly predictive of impaired personality functioning after controlling for psychological distress. It is concluded that the CAT-PD-SF is a promising tool for the assessment of personality disorder traits.
Reliability-based optimization of engineering structures
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
2008-01-01
The theoretical basis for reliability-based structural optimization within the framework of Bayesian statistical decision theory is briefly described. Reliability-based cost benefit problems are formulated and exemplitied with structural optimization. The basic reliability-based optimization...... problems are generalized to the following extensions: interactive optimization, inspection and repair costs, systematic reconstruction, re-assessment of existing structures. Illustrative examples are presented including a simple introductory example, a decision problem related to bridge re...
Kang, Jee In; Chung, Hyun Cheol; Kim, Se Joo; Choi, Hye Jin; Ahn, Joong Bae; Jeung, Hei-Cheul; Namkoong, Kee
2008-06-01
Mental adjustment and coping affect the physical outcome and survival as well as quality of life in cancer patients. The Mini-Mental Adjustment to Cancer (Mini-MAC) scale is a new refined, economical and reliable self-rating instrument measuring cognitive and behavioral responses to cancer. The aim of this study was to evaluate the psychometric properties of the Mini-MAC in Korean cancer patients. A total of 208 cancer patients recruited from the Yonsei Cancer Center were assessed with the Mini-MAC and the Hospital Anxiety and Depression Scale (HADS). Principal component analysis with varimax rotation for the Korean version of Mini-MAC (K-Mini-MAC) confirmed four factors. Three had psychometric properties similar to Helpless-Hopeless (HH), Anxious Preoccupation (AP) and Cognitive Avoidance (CA) of the original Mini-MAC. A novel factor, named Positive Attitude, included items of both Fatalism (FA) and Fighting Spirit (FS) from the original version. The five subscales from the original version (AP, HH, FS, FA and CA) and Positive Attitude had acceptable internal reliabilities in our sample (Cronbach's alpha coefficient 0.50-0.86; correlation coefficient of test-retest 0.68-0.88). For the validity, significant interscale correlation was observed in the original five subscales and Positive Attitude. Each subscale including Positive Attitude was also significantly related to Depression and Anxiety of HADS. As a whole, the K-Mini-MAC was a reliable, valid and acceptable tool for Korean cancer patients. These findings can provide information about the cross-cultural validity of Mini-MAC scale's factor structure. Cultural differences were also discussed.
Hardy, Precious; Aruguete, Mara
2014-01-01
Retention is a major problem in most colleges and universities. High dropout rates, especially in the STEM disciplines (science, technology, engineering and mathematics), have proved intractable despite the offering of supplemental instruction. A broad model of support systems that includes psychological factors is needed to address retention in…
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Friis-Hansen, P.; Nielsen, J.S.
2006-01-01
failure/collapse of jacket type platforms with wave in deck loads using the so-called Model Correction Factor Method (MCFM). A simple representative model for the RSR measure is developed and used in the MCFM technique. A realistic example is evaluated and it is seen that it is possible to perform...
Reliability based Robustness of Timber Structures through NDT Data Updating
DEFF Research Database (Denmark)
Sousa, Hélder S.; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning
2011-01-01
This work presents a framework for reliability-based assessment of timber structures / members using data gathered from non-destructive test results. These results are used for modeling an update of the mechanical characteristics of timber, using Bayesian methods. Results gathered from ultrasound...... of the structure, thus, being possible to evaluate reliability based in time dependent factors, as well to categorize that structure in terms of robustness. For exemplification of the underlined concepts, three different types of structures are studied....
Nguyen, Trang Quynh; Poteat, Tonia; Bandeen-Roche, Karen; German, Danielle; Nguyen, Yen Hai; Vu, Loan Kieu-Chau; Nguyen, Nam Thi-Thu; Knowlton, Amy R
2016-08-01
We developed the first Vietnamese Internalized Homophobia (IH) scale for use with Vietnamese sexual minority women (SMW). Drawing from existing IH scales in the international literature and based on prior qualitative research about SMW in the Viet Nam context, the scale covers two domains: self-stigma (negative attitudes toward oneself as a sexual minority person) and sexual prejudice (negative attitudes toward homosexuality/same-sex relations in general). Scale items, including items borrowed from existing scales and items based on local expressions, were reviewed and confirmed by members of the target population. Quantitative evaluation used data from an anonymous web-based survey of Vietnamese SMW, including those who identified as lesbian (n = 1187), or as bisexual (n = 641) and those who were unsure about their sexual identity (n = 353). The scale was found to consist of two highly correlated factors reflecting self-stigma (not normal/wholesome and self-reproach and wishing away same-sex sexuality) and one factor reflecting sexual prejudice, and to have excellent internal consistency. Construct validity was evidenced by subscale associations with a wide range of hypothesized correlates, including perceived sexual stigma, outness, social support, connection to other SMW, relationship quality, psychological well-being, anticipation of heterosexual marriage, and endorsement of same-sex marriage legalization. Self-stigma was more strongly associated with psychosocial correlates, and sexual prejudice was more associated with endorsement of legal same-sex marriage. The variations in these associations across the hypothesized correlates and across sexual identity groups were consistent with the minority stress model and the IH literature, and exhibited context-specific features, which are discussed.
Fornaro, Michele; Elassy, Mai; Mounir, Mina; Abd-Elmoneim, Noran; Ashour, Hala; Hamed, Rania; Al-Shehri, Abdullah; Bedir, Samir; Rashed, Ibrahem; Amer, Noha; Mohammed, Talal A; De Berardis, Domenico; Mazza, Monica; Pino, Mariachiara; Koshy, Ann Sarah; De Pasquale, Concetta; Okasha, Tarek; Angst, Jules
2015-05-01
To assess the psychometric properties of the Arabic adaptation of the Hypomania-Check-List 32-item, second revision (HCL-32-R2) for the detection of bipolarity in major depressive disorder (MDD) inpatients suffering a current major depressive episode (MDE). The "Bipolar Disorders: Improving Diagnosis, Guidance, and Education" Arabic module of the HCL-32-R2 was administered to mother-tongue Arabic MDE inpatients between March 2013 and October 2014. Diagnostic and Statistical Manual Fourth edition (DSM-IV) diagnoses were made adopting the mini-international neuropsychiatric interview, using bipolar disorder (BD) patients as controls. In our sample (n=500, of whom, BD-I=329; BD-II=70; MDD=101), using a cut-off of 17 allowed the HCL-32-R2 to discriminate DSM-IV-defined MDD patients between "true unipolar" (HCL-32-R2(-)) and "sub-threshold bipolar depression" (HCL-32-R2(+)) with sensitivity=82% and specificity=77%. Area under the curve was .883; positive and negative predictive values were 93.44% and 73.23% respectively. Owing to clinical interpretability considerations and consistency with previous adaptations of the HCL-32, a two-factor solution (F1="hyperactive/elated" vs. F2="irritable/distractible/impulsive") was preferred using exploratory and confirmatory factors analyses. Item n.33 ("I gamble more") and n.34 ("I eat more") introduced in the R2 version of the HCL-32 loaded onto F1, though very slightly. Cronbach's alphas were F1=.86 and F2=.60. No cross-validation with any additional validated screening tool. Inpatients only sample; recall bias; no systematic evaluation of eventual medical/psychiatric comorbidities, current/lifetime pharmacological history, or record of severity of current MDE. In our sample, the HCL-32 fairly discriminated between MDD and BD-I but not BD-II, therefore soliciting for replication studies for use in Arabic-speaking depressed inpatients. Copyright © 2015. Published by Elsevier Inc.
Holm, Søren; Hofmann, Bjørn
2017-10-01
A precondition for reducing scientific misconduct is evidence about scientists' attitudes. We need reliable survey instruments, and this study investigates the reliability of Kalichman's "Survey 2: research misconduct" questionnaire. The study is a post hoc analysis of data from three surveys among biomedical doctoral students in Scandinavia (2010-2015). We perform reliability analysis, and exploratory and confirmatory factor analysis using a split-sample design as a partial validation. The results indicate that a reliable 13-item scale can be formed (Cronbach's α = .705), and factor analysis indicates that there are four reliable subscales each tapping a different construct: (a) general attitude to misconduct (α = .768), (b) attitude to personal misconduct (α = .784), (c) attitude to whistleblowing (α = .841), and (d) attitude to blameworthiness/punishment (α = .877). A full validation of the questionnaire requires further research. We, nevertheless, hope that the results will facilitate the increased use of the questionnaire in research.
Reliability Based Optimization of Structural Systems
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
1987-01-01
The optimization problem to design structural systems such that the reliability is satisfactory during the whole lifetime of the structure is considered in this paper. Some of the quantities modelling the loads and the strength of the structure are modelled as random variables. The reliability...... is estimated using first. order reliability methods ( FORM ). The design problem is formulated as the optimization problem to minimize a given cost function such that the reliability of the single elements satisfies given requirements or such that the systems reliability satisfies a given requirement....... For these optimization problems it is described how a sensitivity analysis can be performed. Next, new optimization procedures to solve the optimization problems are presented. Two of these procedures solve the system reliability based optimization problem sequentially using quasi-analytical derivatives. Finally...
Zimmermann, Gregoire; Mahaim, Elodie Biermann; Mantzouranis, Gregory; Genoud, Philippe A.; Crocetti, Elisabetta
2012-01-01
The purpose of this study was to evaluate the factor structure and the reliability of the French versions of the Identity Style Inventory (ISI-3) and the Utrecht-Management of Identity Commitments Scale (U-MICS) in a sample of college students (N = 457, 18-25 years old). Confirmatory factor analyses confirmed the hypothesized three-factor solution…
On industrial application of structural reliability theory
Energy Technology Data Exchange (ETDEWEB)
Thoft-Christensen, P
1998-06-01
In this paper it is shown that modern structural reliability theory is being successfully applied to a number of different industries. This review of papers is in no way complete. In the literature there is a large number of similar applications and also application not touched on in this presentation. There has been some concern among scientists from this area that structural reliability theory is not being used by industry. It is probably correct that structural reliability theory is not being used by industry as much as it should be used. However, the work by the ESReDA Working Group clearly shows the vary wide application of structural reliability theory by many different industries. One must also have in mind that industry often is reluctant to publish data related to safety and reliability. (au) 32 refs.
On industrial application of structural reliability theory
International Nuclear Information System (INIS)
Thoft-Christensen, P.
1998-01-01
In this paper it is shown that modern structural reliability theory is being successfully applied to a number of different industries. This review of papers is in no way complete. In the literature there is a large number of similar applications and also application not touched on in this presentation. There has been some concern among scientists from this area that structural reliability theory is not being used by industry. It is probably correct that structural reliability theory is not being used by industry as much as it should be used. However, the work by the ESReDA Working Group clearly shows the vary wide application of structural reliability theory by many different industries. One must also have in mind that industry often is reluctant to publish data related to safety and reliability. (au)
Reliability analysis and assessment of structural systems
International Nuclear Information System (INIS)
Yao, J.T.P.; Anderson, C.A.
1977-01-01
The study of structural reliability deals with the probability of having satisfactory performance of the structure under consideration within any specific time period. To pursue this study, it is necessary to apply available knowledge and methodology in structural analysis (including dynamics) and design, behavior of materials and structures, experimental mechanics, and the theory of probability and statistics. In addition, various severe loading phenomena such as strong motion earthquakes and wind storms are important considerations. For three decades now, much work has been done on reliability analysis of structures, and during this past decade, certain so-called 'Level I' reliability-based design codes have been proposed and are in various stages of implementation. These contributions will be critically reviewed and summarized in this paper. Because of the undesirable consequences resulting from the failure of nuclear structures, it is important and desirable to consider the structural reliability in the analysis and design of these structures. Moreover, after these nuclear structures are constructed, it is desirable for engineers to be able to assess the structural reliability periodically as well as immediately following the occurrence of severe loading conditions such as a strong-motion earthquake. During this past decade, increasing use has been made of techniques of system identification in structural engineering. On the basis of non-destructive test results, various methods have been developed to obtain an adequate mathematical model (such as the equations of motion with more realistic parameters) to represent the structural system
Reliability analysis of RC containment structures under combined loads
International Nuclear Information System (INIS)
Hwang, H.; Reich, M.; Kagami, S.
1984-01-01
This paper discusses a reliability analysis method and load combination design criteria for reinforced concrete containment structures under combined loads. The probability based reliability analysis method is briefly described. For load combination design criteria, derivations of the load factors for accidental pressure due to a design basis accident and safe shutdown earthquake (SSE) for three target limit state probabilities are presented
Directory of Open Access Journals (Sweden)
Tsuchiyagaito A
2017-05-01
Full Text Available Aki Tsuchiyagaito,1–3 Satoshi Horiuchi,4 Toko Igarashi,5 Yoshiya Kawanori,4 Yoshiyuki Hirano,1,3 Hirooki Yabe,2 Akiko Nakagawa1,3 1Research Center for Child Mental Development, Chiba University, Chiba, 2Department of Neuropsychiatry, Fukushima Medical University, Fukushima, 3United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka, 4Faculty of Social Welfare, Iwate Prefectural University, Iwate, 5Graduate School of Education, Joetsu University of Education, Niigata, Japan Background: The Hoarding Rating Scale-Self-Report (HRS-SR is a five-item scale that assesses the symptoms of hoarding. These symptoms include excessive acquisition, difficulty in discarding, and excessive clutter that causes distress. We conducted three studies to examine the factor structure, reliability, and validity of the Japanese version of the HRS-SR (HRS-SR-J. Methods: Study 1 examined its reliability; 193 college students and 320 adolescents and adults completed the HRS-SR-J and, of the college students, 32 took it again 2 weeks later. Study 2 aimed to confirm that its scores in a sample of 210 adolescents and adults are independent of social desirability. Study 3 aimed to validate the HRS-SR-J in the aspects of convergent and discriminant validity in a sample of 550 adults. Results: The HRS-SR-J showed good internal consistency and 2-week test–retest reliability. Based on the nonsignificant correlations between the HRS-SR-J and social desirability, the HRS-SR-J was not strongly affected by social desirability. In addition, it also had a good convergent validity with the Japanese version of the Saving Inventory-Revised (SI-R-J and the hoarding subscale of the Obsessive-Compulsive Inventory, while having a significantly weaker correlation with the five subscales of the Obsessive-Compulsive Inventory, except for the hoarding subscale. In addition, the
Reliability of structural systems subject to fatigue
International Nuclear Information System (INIS)
Rackwitz, R.
1984-01-01
Concepts and computational procedures for the reliability calculation of structural systems subject to fatigue are outlined. Systems are dealt with by approximately computing componential times to first failure. So-called first-order reliability methods are then used to formulate dependencies between componential failures and to evaluate the system failure probability. (Author) [pt
Reliability-Based Optimization of Structural Elements
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
In this paper structural elements from an optimization point of view are considered, i.e. only the geometry of a structural element is optimized. Reliability modelling of the structural element is discussed both from an element point of view and from a system point of view. The optimization...
Development in structural systems reliability theory
International Nuclear Information System (INIS)
Murotsu, Y.
1986-01-01
This paper is concerned with two topics on structural systems reliability theory. One covers automatic generation of failure mode equations, identifications of stochastically dominant failure modes, and reliability assessment of redundant structures. Reduced stiffness matrixes and equivalent nodal forces representing the failed elements are introduced for expressing the safety of the elements, using a matrix method. Dominant failure modes are systematically selected by a branch-and-bound technique and heuristic operations. The other discusses the various optimum design problems based on reliability concept. Those problems are interpreted through a solution to a multi-objective optimization problem. (orig.)
Development in structural systems reliability theory
Energy Technology Data Exchange (ETDEWEB)
Murotsu, Y
1986-07-01
This paper is concerned with two topics on structural systems reliability theory. One covers automatic generation of failure mode equations, identifications of stochastically dominant failure modes, and reliability assessment of redundant structures. Reduced stiffness matrixes and equivalent nodal forces representing the failed elements are introduced for expressing the safety of the elements, using a matrix method. Dominant failure modes are systematically selected by a branch-and-bound technique and heuristic operations. The other discusses the various optimum design problems based on reliability concept. Those problems are interpreted through a solution to a multi-objective optimization problem.
Recent advances in computational structural reliability analysis methods
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.
Reliability analysis of prestressed concrete containment structures
International Nuclear Information System (INIS)
Jiang, J.; Zhao, Y.; Sun, J.
1993-01-01
The reliability analysis of prestressed concrete containment structures subjected to combinations of static and dynamic loads with consideration of uncertainties of structural and load parameters is presented. Limit state probabilities for given parameters are calculated using the procedure developed at BNL, while that with consideration of parameter uncertainties are calculated by a fast integration for time variant structural reliability. The limit state surface of the prestressed concrete containment is constructed directly incorporating the prestress. The sensitivities of the Choleskey decomposition matrix and the natural vibration character are calculated by simplified procedures. (author)
Reliability-Based Design of Coastal Structures
DEFF Research Database (Denmark)
Burcharth, H. F.
1997-01-01
The objective of this paper is to introduce the application of reliability theory for conceptual design and evaluation of coastal structures. It is without the scope to discuss the validity and quality of the various design formulae available for coastal structures. The contents of the paper is a....... Proceedings Conference of Port and Coastal Engineering in developing countries. Rio de Janeiro, Brazil, 1995....
Structural reliability of atomic power plant
International Nuclear Information System (INIS)
Klemin, A.I.; Polyakov, E.F.
1980-01-01
In 1978 the first specialized technical manual ''Technique of Calculating the Structural Reliability of an Atomic Power Plant and Its Systems in the Design Stage'' was developed. The present article contains information about the main characteristics and capabilities of the manual. The manual gives recommendations concerning the calculations of the reliability of such specific systems as the reactor control and safety system, the system of instrumentation and automatic control, and safety systems. 2 refs
Directory of Open Access Journals (Sweden)
A.N. Madewell
2016-09-01
Full Text Available The data presented in this article are related to the article entitled “Assessing Resilience in Emerging Adulthood: The Resilience Scale (RS, Connor Davidson Resilience Scale (CD-RISC, and Scale of Protective Factors (SPF” (Madewell and Ponce-Garcia, 2016 [1]. The data were collected from a sample of 451 college students from three universities located in the Southwestern region of the United States: 374 from a large public university and 67 from two smaller regional universities. The data from the three universities did not significantly differ in terms of demographics. The data represent participant responses on six measurements to include the Resilience Scale-25 (RS-25, Resilience Scale-14 (RS-14, Connor Davidson Resilience Scale-25 (CD-RISC-25, Connor Davidson Resilience Scale-10 (CD-RISC-10, Scale of Protective Factors-24 (SPF-24, and the Life Stressor Checklist Revised (LSC-R. Keywords: Scale of Protective Factors, Resilience Scale, Connor–Davidson Resilience Scale, Emerging adulthood, Confirmatory factor analysis
Reliability assessment of nuclear structural systems
International Nuclear Information System (INIS)
Reich, M.; Hwang, H.
1983-01-01
Reliability assessment of nuclear structural systems has been receiving more emphasis over the last few years. This paper deals with the recent progress made by the Structural Analysis Division of Brookhaven National Laboratory (BNL), in the development of a probability-based reliability analysis methodology for safety evaluation of reactor containments and other seismic category I structures. An important feature of this methodology is the incorporation of finite element analysis and random vibration theory. By utilizing this method, it is possible to evaluate the safety of nuclear structures under various static and dynamic loads in terms of limit state probability. Progress in other related areas, such as the establishment of probabilistic characteristics for various loads and structural resistance, are also described. Results of an application of the methodology to a realistic reinforced concrete containment subjected to dead and live loads, accidental internal pressures and earthquake ground accelerations are presented
Wood, Mary E; Anderson, Jaime L; Glassmire, David M
2017-06-01
Adjudicative competence is the most frequently referred evaluation in the forensic context, and it is because of this that periodic evaluation of competence assessment instruments is imperative. Among those instruments, the MacArthur Competence Assessment Tool-Criminal Adjudication (MacCAT-CA) has demonstrated adequate psychometric properties suggesting its utility in informing the forensic inquiry. The purpose of the current study was to further investigate the psychometric properties and ultimate utility of subscale scores using archival data from a sample of 103 male and female forensic patients who were hospitalized for competence restoration treatment. Results of the present study suggested adequate internal consistency and good model fit for the factor structure. Interrater reliability was evaluated by comparing the absolute agreement of scores derived from 2 independent research assistants for each of the subscales; 2 of the 3 subscales fell within the acceptable range given established interpretative benchmarks for forensic assessment. Of particular interest was that the Appreciation subscale, while heralding the lowest intraclass correlation coefficient, explained the largest proportion of variance in clinician opinion relative to the other 2 subscales. In other words, the most subjective subscale (as evidenced by the lowest intraclass correlation), explained the largest proportion of variance in ultimate opinion. The authors argue that, although these results are an important consideration in these assessments, they are neither surprising nor entirely problematic when considering the case-specific nature of the inquiries on the subscale, as well as the subjectivity of scoring criteria for each of the Appreciation items. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Structural reliability methods: Code development status
Millwater, Harry R.; Thacker, Ben H.; Wu, Y.-T.; Cruse, T. A.
1991-05-01
The Probabilistic Structures Analysis Method (PSAM) program integrates state of the art probabilistic algorithms with structural analysis methods in order to quantify the behavior of Space Shuttle Main Engine structures subject to uncertain loadings, boundary conditions, material parameters, and geometric conditions. An advanced, efficient probabilistic structural analysis software program, NESSUS (Numerical Evaluation of Stochastic Structures Under Stress) was developed as a deliverable. NESSUS contains a number of integrated software components to perform probabilistic analysis of complex structures. A nonlinear finite element module NESSUS/FEM is used to model the structure and obtain structural sensitivities. Some of the capabilities of NESSUS/FEM are shown. A Fast Probability Integration module NESSUS/FPI estimates the probability given the structural sensitivities. A driver module, PFEM, couples the FEM and FPI. NESSUS, version 5.0, addresses component reliability, resistance, and risk.
Optimal Structural Reliability of Offshore Wind Turbines
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Tarp-Johansen, N.J.
2005-01-01
The main failure modes of modern large wind turbines are fatigue failure of wings, hub, shaft and main tower, local buckling of main tower, and failure of the foundation. This paper considers reliability-based optimal design of wind turbines. Compared to onshore wind turbines and building...... structures, humans spent little time in the vicinity of offshore wind turbines and the probability of human injury during storm conditions is small. Further environmental pollution will also in general be small in case of failure. One could therefore argue that the reliability level of offshore wind turbines...... can be lower than for onshore wind turbines and other civil engineering structures and can be assessed by reliability-based cost-optimization. Specifically this paper considers the main tower and foundation. Both fatigue and ultimate strength failure modes are included. Different formulations...
Evaluation criteria of structural steel reliability
International Nuclear Information System (INIS)
Zav'yalov, A.S.
1980-01-01
Different low-carbon and medium-carbon structural steels are investigated. It is stated that steel reliability evaluation criteria depend on the fracture mode, steel suffering from the brittle fracture under the influence of the stresses (despite their great variety) arising in articles during the production and operation. Fibrous steel fracture at the given temperature and article thickness says about its high ductility and toughness and brittle fractures are impossible. Brittle fractures take place in case of a crystalline and mixed fracture with a predominant crystalline component. Evaluation methods of article and sample steel structural strength differing greatly from real articles in a thickness (diameter) or used at temperatures higher than possible operation temperatures cannot be reliability evaluation criteria because at a great thickness (diameter) and lower operation temperatures steel fracture and its strain mode can change resulting in a sharp reliability degradation
Reliability analysis of an offshore structure
DEFF Research Database (Denmark)
Sorensen, J. D.; Faber, M. H.; Thoft-Christensen, P.
1992-01-01
A jacket type offshore structure from the North Sea is considered. The time variant reliability is estimated for failure defined as brittle fracture and crack through the tubular member walls. The stochastic modelling is described. The hot spot stress spectral moments as function of the stochasti...
On Industrial Application of Structural Reliability Theory
DEFF Research Database (Denmark)
Thoft-Christensen, Palle
For the last two decades we have seen an increasing interest in applying structural reliability theory to many different industries. However, the number of real applications is much smaller than what one would expect. At the beginning most applications were in the design/analyses area especially...
Human factors reliability benchmark exercise: a review
International Nuclear Information System (INIS)
Humphreys, P.
1990-01-01
The Human Factors Reliability Benchmark Exercise has addressed the issues of identification, analysis, representation and quantification of Human Error in order to identify the strengths and weaknesses of available techniques. Using a German PWR nuclear powerplant as the basis for the studies, fifteen teams undertook evaluations of a routine functional Test and Maintenance procedure plus an analysis of human actions during an operational transient. The techniques employed by the teams are discussed and reviewed on a comparative basis. The qualitative assessments performed by each team compare well, but at the quantification stage there is much less agreement. (author)
Reliability Analysis of Elasto-Plastic Structures
DEFF Research Database (Denmark)
Thoft-Christensen, Palle; Sørensen, John Dalsgaard
1984-01-01
. Failure of this type of system is defined either as formation of a mechanism or by failure of a prescribed number of elements. In the first case failure is independent of the order in which the elements fail, but this is not so by the second definition. The reliability analysis consists of two parts...... are described and the two definitions of failure can be used by the first formulation, but only the failure definition based on formation of a mechanism by the second formulation. The second part of the reliability analysis is an estimate of the failure probability for the structure on the basis...
Reliability and Robustness Evaluation of Timber Structures
DEFF Research Database (Denmark)
Cizmar, Dean; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning
In the last few decades there have been intensely research concerning reliability of timber structures. This is primarily because there is an increased focus on society on sustainability and environmental aspects. Modern timber as a building material is also being competitive compared to concrete...... and steel. However, reliability models applied to timber were always related to individual components but not the systems. as any real structure is a complex system, system behaviour must be of a particular interest. In the chapter 1 of this document an overview of stochastic models for strength and loads...... (deterministic, probabilistic and risk based approaches) of the robustness are given. Chapter 3 deals more detailed with the robustness of timber structures....
Structural reliability analysis and seismic risk assessment
International Nuclear Information System (INIS)
Hwang, H.; Reich, M.; Shinozuka, M.
1984-01-01
This paper presents a reliability analysis method for safety evaluation of nuclear structures. By utilizing this method, it is possible to estimate the limit state probability in the lifetime of structures and to generate analytically the fragility curves for PRA studies. The earthquake ground acceleration, in this approach, is represented by a segment of stationary Gaussian process with a zero mean and a Kanai-Tajimi Spectrum. All possible seismic hazard at a site represented by a hazard curve is also taken into consideration. Furthermore, the limit state of a structure is analytically defined and the corresponding limit state surface is then established. Finally, the fragility curve is generated and the limit state probability is evaluated. In this paper, using a realistic reinforced concrete containment as an example, results of the reliability analysis of the containment subjected to dead load, live load and ground earthquake acceleration are presented and a fragility curve for PRA studies is also constructed
Human factors considerations for reliability and safety
International Nuclear Information System (INIS)
Carnino, A.
1985-01-01
Human factors in many industries have become an important issue, since the last few years. They should be considered during the whole life time of a plant: design, fabrication and construction, licensing, operation. Improvements have been performed in the field of man-machine interface such as procedures, control room lay-out, operator aids, training. In order to meet the needs of reliability and probabilistic risk studies, quantification of human errors has been developed but needs still improvements in the field of cognitive behaviour, diagnosis and representation errors. Data banks to support these quantifications are still in a development stage. This applies to nuclear power plants and several examples are given to illustrate the above ideas. In conclusion, human factors field is in a very quickly evolving process but the tendency is still to adapt the man to the machines whilst the reverse would be desirable
Estimation of structural reliability under combined loads
International Nuclear Information System (INIS)
Shinozuka, M.; Kako, T.; Hwang, H.; Brown, P.; Reich, M.
1983-01-01
For the overall safety evaluation of seismic category I structures subjected to various load combinations, a quantitative measure of the structural reliability in terms of a limit state probability can be conveniently used. For this purpose, the reliability analysis method for dynamic loads, which has recently been developed by the authors, was combined with the existing standard reliability analysis procedure for static and quasi-static loads. The significant parameters that enter into the analysis are: the rate at which each load (dead load, accidental internal pressure, earthquake, etc.) will occur, its duration and intensity. All these parameters are basically random variables for most of the loads to be considered. For dynamic loads, the overall intensity is usually characterized not only by their dynamic components but also by their static components. The structure considered in the present paper is a reinforced concrete containment structure subjected to various static and dynamic loads such as dead loads, accidental pressure, earthquake acceleration, etc. Computations are performed to evaluate the limit state probabilities under each load combination separately and also under all possible combinations of such loads
Lower bounds to the reliabilities of factor score estimators
Hessen, D.J.
2017-01-01
Under the general common factor model, the reliabilities of factor score estimators might be of more interest than the reliability of the total score (the unweighted sum of item scores). In this paper, lower bounds to the reliabilities of Thurstone’s factor score estimators, Bartlett’s factor score
Prediction of software operational reliability using testing environment factors
International Nuclear Information System (INIS)
Jung, Hoan Sung; Seong, Poong Hyun
1995-01-01
A number of software reliability models have been developed to estimate and to predict software reliability. However, there are no established standard models to quantify software reliability. Most models estimate the quality of software in reliability figures such as remaining faults, failure rate, or mean time to next failure at the testing phase, and they consider them ultimate indicators of software reliability. Experience shows that there is a large gap between predicted reliability during development and reliability measured during operation, which means that predicted reliability, or so-called test reliability, is not operational reliability. Customers prefer operational reliability to test reliability. In this study, we propose a method that predicts operational reliability rather than test reliability by introducing the testing environment factor that quantifies the changes in environments
Influence of organizational factors on performance reliability
International Nuclear Information System (INIS)
Haber, S.B.; O'Brien, J.N.; Metlay, D.S.; Crouch, D.A.
1991-12-01
This is the first volume of a two-volume report. Volume 2 will be published at a later date. This report presents the results of a research project conducted by Brookhaven National Laboratory for the United States Nuclear Regulatory Commission, Office of Nuclear Regulatory Research. The purpose of the project was to develop a general methodology to be use in the assessment of the organizational factors which affect performance reliability (safety) in a nuclear power plant. The research described in this report includes the development of the Nuclear Organization and Management Analysis Concept (GNOMIC). This concept characterizes the organizational factors that impact safety performance in a nuclear power plant and identifies some methods for systematically measuring and analyzing the influence of these factors on safety performance. This report is divided into two parts; Part 1 presents an overview of the development of the methodology, while Part 2 provides more details and a technical analysis of the methodological development. Specifically, the results of two demonstration studies, the feasibility of the methodology, and a specific applications for which the methodology was developed are presented
Identifying factors influencing reliability of professional systems
Balasubramanian, A.; Kevrekidis, K.; Sonnemans, P.J.M.; Newby, M.J.
2008-01-01
Modern product development strategies call for a more proactive approach to fight intense global competition in terms of technological innovation, shorter time to market, quality and reliability and accommodative price. From a reliability engineering perspective, development managers would like to
Prediction of software operational reliability using testing environment factors
International Nuclear Information System (INIS)
Jung, Hoan Sung; Seong, Poong Hyun
1995-01-01
For many years, many researches have focused on the quantification of software reliability and there are many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. The experiences show that the operational reliability is higher than the test reliability User's interest is on the operational reliability rather than on the test reliability, however. With the assumption that the difference in reliability results from the change of environment, testing environment factors comprising the aging factor and the coverage factor are defined in this study to predict the ultimate operational reliability with the failure data. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results are close to the actual data
Subset simulation for structural reliability sensitivity analysis
International Nuclear Information System (INIS)
Song Shufang; Lu Zhenzhou; Qiao Hongwei
2009-01-01
Based on two procedures for efficiently generating conditional samples, i.e. Markov chain Monte Carlo (MCMC) simulation and importance sampling (IS), two reliability sensitivity (RS) algorithms are presented. On the basis of reliability analysis of Subset simulation (Subsim), the RS of the failure probability with respect to the distribution parameter of the basic variable is transformed as a set of RS of conditional failure probabilities with respect to the distribution parameter of the basic variable. By use of the conditional samples generated by MCMC simulation and IS, procedures are established to estimate the RS of the conditional failure probabilities. The formulae of the RS estimator, its variance and its coefficient of variation are derived in detail. The results of the illustrations show high efficiency and high precision of the presented algorithms, and it is suitable for highly nonlinear limit state equation and structural system with single and multiple failure modes
Estimation of structural reliability under combined loads
International Nuclear Information System (INIS)
Shinozuka, M.; Kako, T.; Hwang, H.; Brown, P.; Reich, M.
1983-01-01
For the overall safety evaluation of seismic category I structures subjected to various load combinations, a quantitative measure of the structural reliability in terms of a limit state probability can be conveniently used. For this purpose, the reliability analysis method for dynamic loads, which has recently been developed by the authors, was combined with the existing standard reliability analysis procedure for static and quasi-static loads. The significant parameters that enter into the analysis are: the rate at which each load (dead load, accidental internal pressure, earthquake, etc.) will occur, its duration and intensity. All these parameters are basically random variables for most of the loads to be considered. For dynamic loads, the overall intensity is usually characterized not only by their dynamic components but also by their static components. The structure considered in the present paper is a reinforced concrete containment structure subjected to various static and dynamic loads such as dead loads, accidental pressure, earthquake acceleration, etc. Computations are performed to evaluate the limit state probabilities under each load combination separately and also under all possible combinations of such loads. Indeed, depending on the limit state condition to be specified, these limit state probabilities can indicate which particular load combination provides the dominant contribution to the overall limit state probability. On the other hand, some of the load combinations contribute very little to the overall limit state probability. These observations provide insight into the complex problem of which load combinations must be considered for design, for which limit states and at what level of limit state probabilities. (orig.)
Somma, Antonella; Borroni, Serena; Maffei, Cesare; Giarolli, Laura E; Markon, Kristian E; Krueger, Robert F; Fossati, Andrea
2017-10-01
In order to assess the reliability, factorial validity, and criterion validity of the Personality Inventory for DSM-5 (PID-5) among adolescents, 1,264 Italian high school students were administered the PID-5. Participants were also administered the Questionnaire on Relationships and Substance Use as a criterion measure. In the full sample, McDonald's ω values were adequate for the PID-5 scales (median ω = .85, SD = .06), except for Suspiciousness. However, all PID-5 scales showed average inter-item correlation values in the .20-.55 range. Exploratory structural equation modeling analyses provided moderate support for the a priori model of PID-5 trait scales. Ordinal logistic regression analyses showed that selected PID-5 trait scales predicted a significant, albeit moderate (Cox & Snell R 2 values ranged from .08 to .15, all ps < .001) amount of variance in Questionnaire on Relationships and Substance Use variables.
Jimenez-Pardo, J; Holmes, J D; Jenkins, M E; Johnson, A M
2015-07-01
Physical activity is generally thought to be beneficial to individuals with Parkinson's disease (PD). There is, however, limited information regarding current rates of physical activity among individuals with PD, possibly due to a lack of well-validated measurement tools. In the current study we sampled 63 individuals (31 women) living with PD between the ages of 52 and 87 (M = 70.97 years, SD = 7.53), and evaluated the amount of physical activity in which they engaged over a 7-day period using a modified form of the Physical Activity Scale for Individuals with Physical Disabilities (PASIPD). The PASIPD was demonstrated to be a reliable measure within this population, with three theoretically defensible factors: (1) housework and home-based outdoor activities; (2) recreational and fitness activities; and (3) occupational activities. These results suggest that the PASIPD may be useful for monitoring physical activity involvement among individuals with PD, particularly within large-scale questionnaire-based studies.
Structural Reliability Analysis of Wind Turbines: A Review
Directory of Open Access Journals (Sweden)
Zhiyu Jiang
2017-12-01
Full Text Available The paper presents a detailed review of the state-of-the-art research activities on structural reliability analysis of wind turbines between the 1990s and 2017. We describe the reliability methods including the first- and second-order reliability methods and the simulation reliability methods and show the procedure for and application areas of structural reliability analysis of wind turbines. Further, we critically review the various structural reliability studies on rotor blades, bottom-fixed support structures, floating systems and mechanical and electrical components. Finally, future applications of structural reliability methods to wind turbine designs are discussed.
Reliability analysis applied to structural tests
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.
Sensitivity analysis in a structural reliability context
International Nuclear Information System (INIS)
Lemaitre, Paul
2014-01-01
This thesis' subject is sensitivity analysis in a structural reliability context. The general framework is the study of a deterministic numerical model that allows to reproduce a complex physical phenomenon. The aim of a reliability study is to estimate the failure probability of the system from the numerical model and the uncertainties of the inputs. In this context, the quantification of the impact of the uncertainty of each input parameter on the output might be of interest. This step is called sensitivity analysis. Many scientific works deal with this topic but not in the reliability scope. This thesis' aim is to test existing sensitivity analysis methods, and to propose more efficient original methods. A bibliographical step on sensitivity analysis on one hand and on the estimation of small failure probabilities on the other hand is first proposed. This step raises the need to develop appropriate techniques. Two variables ranking methods are then explored. The first one proposes to make use of binary classifiers (random forests). The second one measures the departure, at each step of a subset method, between each input original density and the density given the subset reached. A more general and original methodology reflecting the impact of the input density modification on the failure probability is then explored. The proposed methods are then applied on the CWNR case, which motivates this thesis. (author)
Study of structural reliability of existing concrete structures
Druķis, P.; Gaile, L.; Valtere, K.; Pakrastiņš, L.; Goremikins, V.
2017-10-01
Structural reliability of buildings has become an important issue after the collapse of a shopping center in Riga 21.11.2013, caused the death of 54 people. The reliability of a building is the practice of designing, constructing, operating, maintaining and removing buildings in ways that ensure maintained health, ward suffered injuries or death due to use of the building. Evaluation and improvement of existing buildings is becoming more and more important. For a large part of existing buildings, the design life has been reached or will be reached in the near future. The structures of these buildings need to be reassessed in order to find out whether the safety requirements are met. The safety requirements provided by the Eurocodes are a starting point for the assessment of safety. However, it would be uneconomical to require all existing buildings and structures to comply fully with these new codes and corresponding safety levels, therefore the assessment of existing buildings differs with each design situation. This case study describes the simple and practical procedure of determination of minimal reliability index β of existing concrete structures designed by different codes than Eurocodes and allows to reassess the actual reliability level of different structural elements of existing buildings under design load.
International Nuclear Information System (INIS)
Jung, Hoan Sung; Seong, Poong Hyun
1999-01-01
It has been a critical issue to predict the safety critical software reliability in nuclear engineering area. For many years, many researches have focused on the quantification of software reliability and there have been many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is however on the operational reliability rather than on the test reliability. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, from testing to operation, testing environment factors comprising the aging factor and the coverage factor are developed in this paper and used to predict the ultimate operational reliability with the failure data in testing phase. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results show that the proposed method can estimate the operational reliability accurately. (Author). 14 refs., 1 tab., 1 fig
Seismic reliability assessment methodology for CANDU concrete containment structures
International Nuclear Information System (INIS)
Stephens, M.J.; Nessim, M.A.; Hong, H.P.
1995-05-01
A study was undertaken to develop a reliability-based methodology for the assessment of existing CANDU concrete containment structures with respect to seismic loading. The focus of the study was on defining appropriate specified values and partial safety factors for earthquake loading and resistance parameters. Key issues addressed in the work were the identification of an approach to select design earthquake spectra that satisfy consistent safety levels, and the use of structure-specific data in the evaluation of structural resistance. (author). 23 refs., 9 tabs., 15 figs
Reliability Analysis of Structural Timber Systems
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Hoffmeyer, P.
2000-01-01
Structural systems like timber trussed rafters and roof elements made of timber can be expected to have some degree of redundancy and nonlinear/plastic behaviour when the loading consists of for example snow or imposed load. In this paper this system effect is modelled and the statistic...... of variation. In the paper a stochastic model is described for the strength of a single piece of timber taking into account the stochastic variation of the strength and stiffness with length. Also stochastic models for different types of loads are formulated. First, simple representative systems with different...... types of redundancy and non-linearity are considered. The statistical characteristics of the load bearing capacity are determined by reliability analysis. Next, more complex systems are considered modelling the mechanical behaviour of timber roof elements I stressed skin panels made of timber. Using...
Neurology objective structured clinical examination reliability using generalizability theory.
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.
Kono, Yuko; Matsushima, Eisuke; Uji, Masayo
2014-02-01
The 25-item Work Limitations Questionnaire (WLQ-25) measures presenteeism but has not been sufficiently validated in a Japanese population. A total of 451 employees from four information technology companies in Tokyo completed the WLQ-25 and questionnaires of other variables on two occasions, 2 weeks apart. The WLQ-25 yielded a two-factor structure: Cognitive Demand and Physical Demand. These subscales showed good internal consistency, and both were associated with adverse working conditions, greater perceived job strain, lower skill use, poorer workplace social support, and less satisfactory psychological adjustment. Intraclass correlation coefficients of the two WLQ-25 subscales between time 1 and time 2 were 0.78 and 0.55, respectively. This study suggests acceptable psychometric properties of the WLQ-25 in Japan.
Lower Bounds to the Reliabilities of Factor Score Estimators.
Hessen, David J
2016-10-06
Under the general common factor model, the reliabilities of factor score estimators might be of more interest than the reliability of the total score (the unweighted sum of item scores). In this paper, lower bounds to the reliabilities of Thurstone's factor score estimators, Bartlett's factor score estimators, and McDonald's factor score estimators are derived and conditions are given under which these lower bounds are equal. The relative performance of the derived lower bounds is studied using classic example data sets. The results show that estimates of the lower bounds to the reliabilities of Thurstone's factor score estimators are greater than or equal to the estimates of the lower bounds to the reliabilities of Bartlett's and McDonald's factor score estimators.
A methodology to incorporate organizational factors into human reliability analysis
International Nuclear Information System (INIS)
Li Pengcheng; Chen Guohua; Zhang Li; Xiao Dongsheng
2010-01-01
A new holistic methodology for Human Reliability Analysis (HRA) is proposed to model the effects of the organizational factors on the human reliability. Firstly, a conceptual framework is built, which is used to analyze the causal relationships between the organizational factors and human reliability. Then, the inference model for Human Reliability Analysis is built by combining the conceptual framework with Bayesian networks, which is used to execute the causal inference and diagnostic inference of human reliability. Finally, a case example is presented to demonstrate the specific application of the proposed methodology. The results show that the proposed methodology of combining the conceptual model with Bayesian Networks can not only easily model the causal relationship between organizational factors and human reliability, but in a given context, people can quantitatively measure the human operational reliability, and identify the most likely root causes or the prioritization of root causes caused human error. (authors)
Prediction of software operational reliability using testing environment factor
International Nuclear Information System (INIS)
Jung, Hoan Sung
1995-02-01
Software reliability is especially important to customers these days. The need to quantify software reliability of safety-critical systems has been received very special attention and the reliability is rated as one of software's most important attributes. Since the software is an intellectual product of human activity and since it is logically complex, the failures are inevitable. No standard models have been established to prove the correctness and to estimate the reliability of software systems by analysis and/or testing. For many years, many researches have focused on the quantification of software reliability and there are many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is on the operational reliability rather than on the test reliability, however. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, testing environment factor comprising the aging factor and the coverage factor are defined in this work to predict the ultimate operational reliability with the failure data. It is by incorporating test environments applied beyond the operational profile into testing environment factor Test reliability can also be estimated with this approach without any model change. The application results are close to the actual data. The approach used in this thesis is expected to be applicable to ultra high reliable software systems that are used in nuclear power plants, airplanes, and other safety-critical applications
International Nuclear Information System (INIS)
Poucet, A.
1988-01-01
The Joint Research Centre of the European Commission has organised a Human Factors Reliability Benchmark Exercise (HF-RBE) with the aim to assess the state-of-the-art in human reliability modelling and assessment. Fifteen teams from eleven countries, representing industry, utilities, licensing organisations and research institutes, participate in the HF-RBE, which is organised around two study cases: (1) analysis of routine functional test and maintenance procedures, with the aim to assess the probability of test-induced failures, the probability of failures to remain unrevealed, and the potential to initiate transients because of errors performed in the test; and (2) analysis of human actions during an operational transient, with the aim to assess the probability that the operators will correctly diagnose the malfunctions and take proper corrective action. The paper briefly reports how the HF-RBE was structured and gives an overview of the methods that have been used for predicting human reliability in both study cases. The experience in applying these methods is discussed and the results obtained are compared. (author)
Reliability of structural materials in nuclear industry
International Nuclear Information System (INIS)
Pinard Legry, G.
1996-01-01
The reliability of nuclear installations is a fundamental point for the exploitation of nuclear energy. It requires an extensive knowledge of the behaviour of materials in the operating conditions and during the expected service life of the installations. In nuclear power plants multiple risks of failure can exist and are expressed by corrosion and deformation phenomena or by modification in the mechanical characteristics of materials. The knowledge of the evolution with time of a given material requires to take into account the data relative to the material itself, to its environment and to the physical conditions of this environment. The study of materials aging needs a more precise knowledge of the kinetics of phenomena at any scale and of their interactions, and a micro- or macro-modeling of their behaviour during long periods of time. This paper gives an overview of the aging phenomena that occur in the structural materials involved in PWR and fast neutron reactors: thermal aging, generalized corrosion, corrosion under constraint, intergranular corrosion, crack growth under loading, wear, irradiation etc.. (J.S.)
Structural reliability codes for probabilistic design
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager
1997-01-01
probabilistic code format has not only strong influence on the formal reliability measure, but also on the formal cost of failure to be associated if a design made to the target reliability level is considered to be optimal. In fact, the formal cost of failure can be different by several orders of size for two...... different, but by and large equally justifiable probabilistic code formats. Thus, the consequence is that a code format based on decision theoretical concepts and formulated as an extension of a probabilistic code format must specify formal values to be used as costs of failure. A principle of prudence...... is suggested for guiding the choice of the reference probabilistic code format for constant reliability. In the author's opinion there is an urgent need for establishing a standard probabilistic reliability code. This paper presents some considerations that may be debatable, but nevertheless point...
Reliability enhancement of portal frame structure by finite element synthesis
International Nuclear Information System (INIS)
Nakagiri, S.
1989-01-01
The stochastic finite element methods have been applied to the evaluation of structural response and reliability of uncertain structural systems. The structural reliability index of the advanced first-order second moment (AFOSM) method is a candidate of the measure of assessing structural safety and reliability. The reliability index can be evaluated when a baseline design of structures under interest is proposed and the covariance matrix of the probabilistic variables is acquired to represent uncertainties involved in the structure systems. The reliability index thus evaluated is not assured the largest one for the structure. There is left a possibility to enhance the structural reliability for the given covariance matrix by changing the baseline design. From such a viewpoint of structural optimization, some ideas have been proposed to maximize the reliability or to minimize the failure probability of uncertain structural systems. A method of changing the design is proposed to increase the reliability index from its baseline value to another desired value. The reliability index in this paper is calculated mainly by the method of Lagrange multiplier
Future of structural reliability methodology in nuclear power plant technology
Energy Technology Data Exchange (ETDEWEB)
Schueeller, G I [Technische Univ. Muenchen (Germany, F.R.); Kafka, P [Gesellschaft fuer Reaktorsicherheit m.b.H. (GRS), Garching (Germany, F.R.)
1978-10-01
This paper presents the authors' personal view as to which areas of structural reliability in nuclear power plant design need most urgently to be advanced. Aspects of simulation modeling, design rules, codification and specification of reliability, system analysis, probabilistic structural dynamics, rare events and particularly the interaction of systems and structural reliability are discussed. As an example, some considerations of the interaction effects between the protective systems and the pressure vessel are stated. The paper concludes with recommendation for further research.
Human Reliability Analysis for Design: Using Reliability Methods for Human Factors Issues
Energy Technology Data Exchange (ETDEWEB)
Ronald Laurids Boring
2010-11-01
This paper reviews the application of human reliability analysis methods to human factors design issues. An application framework is sketched in which aspects of modeling typically found in human reliability analysis are used in a complementary fashion to the existing human factors phases of design and testing. The paper provides best achievable practices for design, testing, and modeling. Such best achievable practices may be used to evaluate and human system interface in the context of design safety certifications.
Human Reliability Analysis for Design: Using Reliability Methods for Human Factors Issues
International Nuclear Information System (INIS)
Boring, Ronald Laurids
2010-01-01
This paper reviews the application of human reliability analysis methods to human factors design issues. An application framework is sketched in which aspects of modeling typically found in human reliability analysis are used in a complementary fashion to the existing human factors phases of design and testing. The paper provides best achievable practices for design, testing, and modeling. Such best achievable practices may be used to evaluate and human system interface in the context of design safety certifications.
Reliability and maintainability assessment factors for reliable fault-tolerant systems
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.
Hildebrand, Martin; Noteborn, Mirthe G C
2015-01-01
The use of brief, reliable, valid, and practical measures of substance use is critical for conducting individual (risk and need) assessments in probation practice. In this exploratory study, the basic psychometric properties of the Alcohol Use Disorders Identification Test (AUDIT) and the Drug Use Disorders Identification Test (DUDIT) are evaluated. The instruments were administered as an oral interview instead of a self-report questionnaire. The sample comprised 383 offenders (339 men, 44 women). A subset of 56 offenders (49 men, 7 women) participated in the interrater reliability study. Data collection took place between September 2011 and November 2012. Overall, both instruments have acceptable levels of interrater reliability for total scores and acceptable to good interrater reliabilities for most of the individual items. Confirmatory factor analyses (CFA) indicated that the a priori one-, two- and three-factor solutions for the AUDIT did not fit the observed data very well. Principal axis factoring (PAF) supported a two-factor solution for the AUDIT that included a level of alcohol consumption/consequences factor (Factor 1) and a dependence factor (Factor 2), with both factors explaining substantial variance in AUDIT scores. For the DUDIT, CFA and PAF suggest that a one-factor solution is the preferred model (accounting for 62.61% of total variance). The Dutch language versions of the AUDIT and the DUDIT are reliable screening instruments for use with probationers and both instruments can be reliably administered by probation officers in probation practice. However, future research on concurrent and predictive validity is warranted.
Structural reliability in context of statistical uncertainties and modelling discrepancies
International Nuclear Information System (INIS)
Pendola, Maurice
2000-01-01
Structural reliability methods have been largely improved during the last years and have showed their ability to deal with uncertainties during the design stage or to optimize the functioning and the maintenance of industrial installations. They are based on a mechanical modeling of the structural behavior according to the considered failure modes and on a probabilistic representation of input parameters of this modeling. In practice, only limited statistical information is available to build the probabilistic representation and different sophistication levels of the mechanical modeling may be introduced. Thus, besides the physical randomness, other uncertainties occur in such analyses. The aim of this work is triple: 1. at first, to propose a methodology able to characterize the statistical uncertainties due to the limited number of data in order to take them into account in the reliability analyses. The obtained reliability index measures the confidence in the structure considering the statistical information available. 2. Then, to show a methodology leading to reliability results evaluated from a particular mechanical modeling but by using a less sophisticated one. The objective is then to decrease the computational efforts required by the reference modeling. 3. Finally, to propose partial safety factors that are evolving as a function of the number of statistical data available and as a function of the sophistication level of the mechanical modeling that is used. The concepts are illustrated in the case of a welded pipe and in the case of a natural draught cooling tower. The results show the interest of the methodologies in an industrial context. [fr
DEFF Research Database (Denmark)
Franchin, P.; Ditlevsen, Ove Dalager; Kiureghian, Armen Der
2002-01-01
The model correction factor method (MCFM) is used in conjunction with the first-order reliability method (FORM) to solve structural reliability problems involving integrals of non-Gaussian random fields. The approach replaces the limit-state function with an idealized one, in which the integrals ...
System Reliability of Timber Structures with Ductile Behaviour
DEFF Research Database (Denmark)
Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Čizmar, Dean
2011-01-01
The present paper considers the evaluation of timber structures with the focus on robustness due to connection ductility. The robustness analysis is based on the structural reliability framework applied to a simplified mechanical system. The structural timber system is depicted as a parallel system....... An evaluation method of the ductile behaviour is introduced. For different ductile behaviours, the system reliability is estimated based on Monte Carlo simulation. A correlation between the strength of the structural elements is introduced. The results indicate that the reliability of a structural timber system...
Sensitivity evaluation of human factors for reliability of the containment spray system
International Nuclear Information System (INIS)
Tsujimura, Yasuhiro; Suzuki, Eiji
1988-01-01
Evaluation of the human reliability is one of the most difficult problems that deal with the safety and reliability of large systems, especially of the Engineered Safety Features (ESF) of the nuclear power plant. Influences of human factors on the reliability of the Containment Spray System in the ESF were estimated by using the FTA method in this paper. As a result, the adequacy of the system structure and the effects of human factors on variations of the design of the system structure were explained. (author)
Nguyen, Trang Quynh; Poteat, Tonia; Bandeen-Roche, Karen; German, Danielle; Nguyen, Yen Hai; Vu, Loan Kieu-Chau; Nguyen, Nam Thi-Thu; Knowlton, Amy R.
2016-01-01
We developed the first Vietnamese internalized homophobia (IH) scale, for use with Vietnamese sexual minority women (SMW). Drawing from existing IH scales in the international literature and based on prior qualitative research about SMW in the Viet Nam context, the scale covers two domains: self-stigma (negative attitudes toward oneself as a sexual minority person) and sexual prejudice (negative attitudes toward homosexuality/same-sex relations in general). Scale items, including items borrowed from existing scales and items based on local expressions, were reviewed and confirmed by members of the target population. Quantitative evaluation used data from an anonymous web-based survey of Vietnamese SMW, including those who identified as lesbian (n=1187), or as bisexual (n=641) and those who were unsure about their sexual identity (n=353). The scale was found to consist of two highly correlated factors reflecting self-stigma (not normal/wholesome and self-reproach and wishing away same-sex sexuality) and one factor reflecting sexual prejudice, and to have excellent internal consistency. Construct validity was evidenced by subscales’ associations with a wide range of hypothesized correlates including perceived sexual stigma, outness, social support, connection to other SMW, relationship quality, psychological well-being, anticipation of heterosexual marriage and endorsement of same-sex marriage legalization. Self-stigma was more strongly associated with psychosocial correlates and sexual prejudice was more associated with endorsement of legal same-sex marriage. The variations in these associations across the hypothesized correlates and across sexual identity groups were consistent with the Minority Stress Model and the IH literature, and exhibited context-specific features, which are discussed. PMID:27007469
Fatigue reliability and calibration of fatigue design factors of wave energy converters
DEFF Research Database (Denmark)
Ambühl, Simon; Ferri, Francesco; Kofoed, Jens Peter
2015-01-01
Target reliability levels, which are chosen dependent on the consequences in case of structural collapse, are used in this paper to calibrate partial safety factors for structural details of wave energy converters (WECs). The consequences in case of structural failure are similar for WECs and off...
Risk-based Optimization and Reliability Levels of Coastal Structures
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Burcharth, H. F.
Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure, in...... on the minimumcost reliability levels is investigated for different values of the real rate of interest, the service lifetime, the downtime costs due to malfunction and the decommission costs.......Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure...
Risk-based Optimization and Reliability Levels of Coastal Structures
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Burcharth, Hans F.
2005-01-01
Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure, i...... on the minimumcost reliability levels is investigated for different values of the real rate of interest, the service lifetime, the downtime costs due to malfunction and the decommission costs....... Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure...
Reliability of Elasto-Plastic Structural Systems
DEFF Research Database (Denmark)
Delmar, M. V.; Sørensen, John Dalsgaard
1990-01-01
This paper proposes a method for generating safety margins and failure mode equations for elasto-plastic structures where interaction of load effects is taken into account. Structural failure is defined by large nodal displacements or plastic collapse. A branch-and-bound technique is used...
Reliability based Design of Coastal Structures
DEFF Research Database (Denmark)
Burcharth, H. F.
2003-01-01
Conventional design practice for coastal structures is deterministic in nature and is based on the concept of a design load which should not exceed the resistance (carrying capacity) of the structure. The design load is usually defined on a probabilistic basis as a characteristic value of the load......, for example the expectation (mean) value of the 100-year return period event. However, this selection is often made without consideration of the involved uncertainties. In most cases the resistance is defined in terms of the load that causes a certain design impact or damage to the structure...
Reliability assessment of Indian Point Unit 3 containment structure
International Nuclear Information System (INIS)
Kawakami, J.; Hwang, H.; Chang, M.T.; Reich, M.
1984-01-01
In the current design criteria, the load combinations specified for design of concrete containment structures are in the deterministic formats. However, by applying the probability-based reliability method developed by BNL to the concrete containment structures designed according to the criteria, it is possible to evaluate the reliability levels implied in the current design criteria. For this purpose, the reliability analysis is applied to the Indian Point Unit No. 3 containment. The details of the containment structure such as the geometries and the rebar arrangements, etc., are taken from the working drawings and the final safety analysis reports. Three kinds of loads are considered in the reliability analysis. They are, dead load (D), accidental pressure due to a large LOCA (P), and earthquake ground acceleration (E). Reliability analysis of the containment subjected to all combinations of loads is performed. Results are presented in this report
Reliability Evaluation of a Structure at Sea
DEFF Research Database (Denmark)
Burcharth, H. F.
1994-01-01
Conventional design practice for coastal structures is deterministic in nature and is based on the concept of a design load, which should not exceed the resistance (carrying capacity) of the structure. The design load is usually defined on a probabilistic basis as a characteristic value of the load......, e.g. the expectation (mean) value of the lOO-year return period event, however, often without consideration of the involved uncertainties. The resistance is in most cases defined in terms of the load which causes a certain design impact or damage to the structure and is not given as an ultimate...... formulae are semi-empirical being based mainly on central fitting to model test results. The often considerable scatter in test results is not considered in general because the formulae normally express only the mean values. Consequently, the applied characteristic value of the resistance is then the mean...
Reliability Evaluation of a Structure at Sea
DEFF Research Database (Denmark)
Burcharth, H. F.
1992-01-01
Conventional design practice for coastal structures is deterministic in nature and is based on the concept of a design load, which should not exceed the resistance (carrying capacity) of the structure. The design load is usually defined on a probabilistic basis as a characteristic value of the load......, e.g. the expectation (mean) value of the 100-year return period event, however, often without consideration of the involved uncertainties. The resistance is in most cases defined in terms of the load which causes a certain design impact or damage to the structure and is not given as an ultimate...... formulae are semi-empirical being based mainly on central fitting to model test results. The often considerable scatter in test results is not considered in general because the formulae normally express only the mean values. Consequently, the applied characteristic value of the resistance is then the mean...
Some aspects of the interaction between systems- and structural reliability
International Nuclear Information System (INIS)
Schueller, G.K.; Schmitt, W.
1979-01-01
The purpose of this paper is to study the interaction between systems- and structural reliability analysis with reference to the design of structural components of LWR. Presently the evaluation of systems reliability is carried out apart from structural reliability analysis. Moreover, two basically different methodologies are used for analysis. While in systems analysis the simplified binary approach is still generally accepted, in structural reliability one has to resort to more sophisticated procedures to obtain realistic results. The interactive effect may be illustrated as follows: For example, the integrity of the primary circuit interacts with the integrity of the containment structure. This means that the probability of occurrence of the pipe rupture which may cause a LOCA and consequently leads to a build-up of temperature and pressure within the containment affects directly its structural reliability. The piping system, particularly the primary piping, in turn interacts with the protective system, which is part of the safety system. This piping structure is also subjected to various operational loading conditions. In a numerical example dealing with leakage probabilities of pipes it is shown how methods of structural reliability may be used to gain more insight in the estimation of failure rates of system components. (orig.)
Reliability prediction for structures under cyclic loads and recurring inspections
Directory of Open Access Journals (Sweden)
Alberto W. S. Mello Jr
2009-06-01
Full Text Available This work presents a methodology for determining the reliability of fracture control plans for structures subjected to cyclic loads. It considers the variability of the parameters involved in the problem, such as initial flaw and crack growth curve. The probability of detection (POD curve of the field non-destructive inspection method and the condition/environment are used as important factors for structural confidence. According to classical damage tolerance analysis (DTA, inspection intervals are based on detectable crack size and crack growth rate. However, all variables have uncertainties, which makes the final result totally stochastic. The material properties, flight loads, engineering tools and even the reliability of inspection methods are subject to uncertainties which can affect significantly the final maintenance schedule. The present methodology incorporates all the uncertainties in a simulation process, such as Monte Carlo, and establishes a relationship between the reliability of the overall maintenance program and the proposed inspection interval, forming a “cascade” chart. Due to the scatter, it also defines the confidence level of the “acceptable” risk. As an example, the damage tolerance analysis (DTA results are presented for the upper cockpit longeron splice bolt of the BAF upgraded F-5EM. In this case, two possibilities of inspection intervals were found: one that can be characterized as remote risk, with a probability of failure (integrity nonsuccess of 1 in 10 million, per flight hour; and other as extremely improbable, with a probability of nonsuccess of 1 in 1 billion, per flight hour, according to aviation standards. These two results are compared with the classical military airplane damage tolerance requirements.
Financial reporting reliability concept and impact factors in its determination
Directory of Open Access Journals (Sweden)
Vygivska I.М.
2017-03-01
Full Text Available The article sets the goal to assess the reliability of financial reporting essence and summarize the factors that affect it. The article grounds the reliability of financial reporting urgency and characterizes its dual nature (on one hand, it is accounting containing reliable, reasonable data, characterized by the absence of errors and can be correctly perceived by users, on the other hand, reliable financial statements are considered to be formed according to the rules regulated by normative documents. It is proved that making decisions by interested users based on financial statements is closely related to information risk that arises because of the restrictions affect the flow of information on which management decisions are taken (accounting information that is difficult to understand by unskilled users, the impact of human factor, the level of information importance. The author establishes that the reliability of financial reporting is affected by many factors whose influence can be seen both outside, and within an enterprise. The main factors include: informational, political, legal, human, organizational and financial and they should be taken into account while making management decisions.
Hai An; Ling Zhou; Hui Sun
2016-01-01
Aiming to resolve the problems of a variety of uncertainty variables that coexist in the engineering structure reliability analysis, a new hybrid reliability index to evaluate structural hybrid reliability, based on the random–fuzzy–interval model, is proposed in this article. The convergent solving method is also presented. First, the truncated probability reliability model, the fuzzy random reliability model, and the non-probabilistic interval reliability model are introduced. Then, the new...
Quantifiable and Reliable Structural Health Management Systems, Phase I
National Aeronautics and Space Administration — Major concerns for implementing a practical built-in structural health monitoring system are prediction accuracy and data reliability. It is proposed to develop...
Reliability-based optimal structural design by the decoupling approach
International Nuclear Information System (INIS)
Royset, J.O.; Der Kiureghian, A.; Polak, E.
2001-01-01
A decoupling approach for solving optimal structural design problems involving reliability terms in the objective function, the constraint set or both is discussed and extended. The approach employs a reformulation of each problem, in which reliability terms are replaced by deterministic functions. The reformulated problems can be solved by existing semi-infinite optimization algorithms and computational reliability methods. It is shown that the reformulated problems produce solutions that are identical to those of the original problems when the limit-state functions defining the reliability problem are affine. For nonaffine limit-state functions, approximate solutions are obtained by solving series of reformulated problems. An important advantage of the approach is that the required reliability and optimization calculations are completely decoupled, thus allowing flexibility in the choice of the optimization algorithm and the reliability computation method
Review of Industrial Applications of Structural Reliability Theory
DEFF Research Database (Denmark)
Thoft-Christensen, Palle
For the last two decades we have seen an increasing interest in applying structural reliability theory to many different industries. However, the number of real practical applications is much smaller than what one would expect.......For the last two decades we have seen an increasing interest in applying structural reliability theory to many different industries. However, the number of real practical applications is much smaller than what one would expect....
Structural Reliability of the Nigerian Grown Abura Timber Bridge ...
African Journals Online (AJOL)
Structural reliability analysis was carried out on the Nigerian grown Abura timber, to ascertain its structural performance as timber bridge beams. Samples of the Nigerian grown Abura timber were bought from timber market, seasoned naturally and their structural/strength properties were determined at a moisture content of ...
Reliability factors of tube-to-tubesheet joints
International Nuclear Information System (INIS)
Sang, Z.F.; Zhu, Y.Z.; Widera, G.E.O.
1992-01-01
The main purpose of this paper is to provide an applicable method to establish reliability factors for expanded tube-to-tubesheet joints. The paper also reports on the results of a preliminary study to validate experimentally the reliability efficiencies listed in Table A-2 of Appendix A of Section VIII, Division 1, of the ASME Boiler and Pressure Vessel Code. A comparison between the actual reliability factors f r , determined from testing the damage strength of the joint and calculated according to Appendix A-4 of the ASME Code, and those of Table A-2 is carried out. The results are discussed in light of the restrictions inherent in Table A-2. It is confirmed that some existing values of f r are conservative while others are less so. (orig.)
Stochastic Finite Elements in Reliability-Based Structural Optimization
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Engelund, S.
1995-01-01
Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to optimi......Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect...... to optimization variables can be performed. A computer implementation is described and an illustrative example is given....
Stochastic Finite Elements in Reliability-Based Structural Optimization
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Engelund, S.
Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to optimi......Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect...
Seismic reliability assessment methodology for CANDU concrete containment structures-phase 11
International Nuclear Information System (INIS)
Hong, H.P.
1996-07-01
This study was undertaken to verify a set of load factors for reliability-based seismic evaluation of CANDU containment structures in Eastern Canada. Here, the new, site-specific, results of probabilistic seismic hazard assessment (response spectral velocity) were applied. It was found that the previously recommended load factors are relatively insensitive to the new seismic hazard information, and are adequate for a reliability-based seismic evaluation process. (author). 4 refs., 5 tabs., 9 figs
Human factors reliability benchmark exercise, report of the SRD participation
International Nuclear Information System (INIS)
Waters, Trevor
1988-01-01
Within the scope of the Human Factors Reliability Benchmark Exercise, organised by the Joint Research Centre, Ispra, Italy, the Safety and Reliability Directorate (SRD) team has performed analysis of human factors in two different activities - a routine test and a non-routine operational transient. For both activities, an 'FMEA-like' task, potential errors, and the factors which affect performance. For analysis of the non-routine activity, which involved a significant amount of cognitive processing, such as diagnosis and decision making, a new approach for qualitative analysis has been developed. Modelling has been performed using both event trees and fault trees and examples are provided. Human error probabilities were estimated using the methods Absolute Probability Judgement (APJ), Human Cognitive Reliability Method (HCR), Human Error and Assessment and Reduction Technique (HEART), Success-Likelihood Index Method (SLIM), Technica Empiriza Stima Eurori Operatori (TESEO), and Technique for Human Error Rate Prediction (THERP). A discussion is provided of the lessons learnt in the course of the exercise and unresolved difficulties in the assessment of human reliability. (author)
Integrated Reliability-Based Optimal Design of Structures
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Thoft-Christensen, Palle
1987-01-01
In conventional optimal design of structural systems the weight or the initial cost of the structure is usually used as objective function. Further, the constraints require that the stresses and/or strains at some critical points have to be less than some given values. Finally, all variables......-based optimal design is discussed. Next, an optimal inspection and repair strategy for existing structural systems is presented. An optimization problem is formulated , where the objective is to minimize the expected total future cost of inspection and repair subject to the constraint that the reliability...... value. The reliability can be measured from an element and/or a systems point of view. A number of methods to solve reliability-based optimization problems has been suggested, see e.g. Frangopol [I]. Murotsu et al. (2], Thoft-Christensen & Sørensen (3] and Sørensen (4). For structures where...
A reliable method for the stability analysis of structures ...
African Journals Online (AJOL)
The detection of structural configurations with singular tangent stiffness matrix is essential because they can be unstable. The secondary paths, especially in unstable buckling, can play the most important role in the loss of stability and collapse of the structure. A new method for reliable detection and accurate computation of ...
Efficiency criteria for high reliability measured system structures
International Nuclear Information System (INIS)
Sal'nikov, N.L.
2012-01-01
The procedures of structural redundancy are usually used to develop high reliability measured systems. To estimate efficiency of such structures the criteria to compare different systems has been developed. So it is possible to develop more exact system by inspection of redundant system data unit stochastic characteristics in accordance with the developed criteria [ru
Interactive Reliability-Based Optimization of Structural Systems
DEFF Research Database (Denmark)
Pedersen, Claus
In order to introduce the basic concepts within the field of reliability-based structural optimization problems, this chapter is devoted to a brief outline of the basic theories. Therefore, this chapter is of a more formal nature and used as a basis for the remaining parts of the thesis. In section...... 2.2 a general non-linear optimization problem and corresponding terminology are presented whereupon optimality conditions and the standard form of an iterative optimization algorithm are outlined. Subsequently, the special properties and characteristics concerning structural optimization problems...... are treated in section 2.3. With respect to the reliability evalutation, the basic theory behind a reliability analysis and estimation of probability of failure by the First-Order Reliability Method (FORM) and the iterative Rackwitz-Fiessler (RF) algorithm are considered in section 2.5 in which...
The evaluation of operator reliability factors on power reactor
International Nuclear Information System (INIS)
Karlina, Itjeu; Supriatna, Piping; W, Suharyo; Santosa, Kussigit; Darlis; S, Bambang; Y, Sasongko
1999-01-01
The sophisticated technology system was not assured the reliability system itself because it has contained a part of human dependence affected successfully of reactor operation either how work smoothly and safe or failure ac cured and then accident appears promptly. The evaluation of operator reliability factor on ABWR power reactor has been carried out which consist of criterion skill and workload according to NUREG/CR-2254, NUREG/CR-4016 and NUREG-0835 the reactor operation reliability emphasize to the operator are synergic between skill and workload themselves. The employee's skill will affect to the type and level of their tasks. The operator's skill depend on education and experiences, position or responsibility of tasks, physical conditions (age uninvalid of physic/mental
Neglect Of Parameter Estimation Uncertainty Can Significantly Overestimate Structural Reliability
Directory of Open Access Journals (Sweden)
Rózsás Árpád
2015-12-01
Full Text Available Parameter estimation uncertainty is often neglected in reliability studies, i.e. point estimates of distribution parameters are used for representative fractiles, and in probabilistic models. A numerical example examines the effect of this uncertainty on structural reliability using Bayesian statistics. The study reveals that the neglect of parameter estimation uncertainty might lead to an order of magnitude underestimation of failure probability.
Structural reliability analysis based on the cokriging technique
International Nuclear Information System (INIS)
Zhao Wei; Wang Wei; Dai Hongzhe; Xue Guofeng
2010-01-01
Approximation methods are widely used in structural reliability analysis because they are simple to create and provide explicit functional relationships between the responses and variables in stead of the implicit limit state function. Recently, the kriging method which is a semi-parameter interpolation technique that can be used for deterministic optimization and structural reliability has gained popularity. However, to fully exploit the kriging method, especially in high-dimensional problems, a large number of sample points should be generated to fill the design space and this can be very expensive and even impractical in practical engineering analysis. Therefore, in this paper, a new method-the cokriging method, which is an extension of kriging, is proposed to calculate the structural reliability. cokriging approximation incorporates secondary information such as the values of the gradients of the function being approximated. This paper explores the use of the cokriging method for structural reliability problems by comparing it with the Kriging method based on some numerical examples. The results indicate that the cokriging procedure described in this work can generate approximation models to improve on the accuracy and efficiency for structural reliability problems and is a viable alternative to the kriging.
Reliability assessment of aging structures subjected to gradual and shock deteriorations
International Nuclear Information System (INIS)
Wang, Cao; Zhang, Hao; Li, Quanwang
2017-01-01
Civil structures and infrastructure facilities are susceptible to deterioration posed by the effects of natural hazards and aggressive environmental conditions. These factors may increase the risk of service interruption of infrastructures, and should be taken into account when assessing the structural reliability during an infrastructure's service life. Modeling the resistance deterioration process reasonably is the basis for structural reliability analysis. In this paper, a novel model is developed for describing the deterioration of aging structures. The deterioration is a combination of two stochastic processes: the gradual deterioration posed by environmental effects and the shock deterioration caused by severe load attacks. The dependency of the deterioration magnitude on the load intensity is considered. The Gaussian copula function is employed to help construct the joint distribution of correlated random variables. Semi-analytical methods are developed to assess the structural failure time and the number of significant load events (shocks) to failure. Illustrative examples are presented to demonstrate the applicability of the proposed model in structural reliability analysis. Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability. - Highlights: • A new resistance deterioration model for aging structures is proposed. • Time-dependent reliability analysis methods incorporating the proposed deterioration model are developed. • Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability.
Study of Fuze Structure and Reliability Design Based on the Direct Search Method
Lin, Zhang; Ning, Wang
2017-03-01
Redundant design is one of the important methods to improve the reliability of the system, but mutual coupling of multiple factors is often involved in the design. In my study, Direct Search Method is introduced into the optimum redundancy configuration for design optimization, in which, the reliability, cost, structural weight and other factors can be taken into account simultaneously, and the redundant allocation and reliability design of aircraft critical system are computed. The results show that this method is convenient and workable, and applicable to the redundancy configurations and optimization of various designs upon appropriate modifications. And this method has a good practical value.
Assessment of structural reliability of precast concrete buildings
Directory of Open Access Journals (Sweden)
Koyankin Alexandr
2018-01-01
Full Text Available Precast housing construction is currently being under rapid development, however, reliability of building structures made from precast reinforced concrete cannot be assessed rationally due to insufficient research data on that subject. In this regard, experimental and numerical studies were conducted to assess structural reliability of precast buildings as described in the given paper. Experimental studies of full-scale and model samples were conducted; numerical studies were held based on finite element models using “Lira” software. The objects under study included fragment of flooring of a building under construction, full-size fragment of flooring, full-scale models of precast cross-beams-to-columns joints and joints between hollow-core floor slabs and precast and cast-in-place cross-beams. Conducted research enabled to perform an objective assessment of structural reliability of precast buildings.
Reliability of redundant structures of nuclear reactor protection systems
International Nuclear Information System (INIS)
Vojnovic, B.
1983-01-01
In this paper, reliability of various redundant structures of PWR protection systems has been analysed. Structures of reactor tip systems as well as the systems for activation of safety devices have been presented. In all those systems redundancy is achieved by means of so called majority voting logic ('r out of n' structures). Different redundant devices have been compared, concerning probability of occurrence of safe as well as unsafe failures. (author)
Reliability evaluation of containments including soil-structure interaction
International Nuclear Information System (INIS)
Pires, J.; Hwang, H.; Reich, M.
1985-12-01
Soil-structure interaction effects on the reliability assessment of containment structures are examined. The probability-based method for reliability evaluation of nuclear structures developed at Brookhaven National Laboratory is extended to include soil-structure interaction effects. In this method, reliability of structures is expressed in terms of limit state probabilities. Furthermore, random vibration theory is utilized to calculate limit state probabilities under random seismic loads. Earthquake ground motion is modeled by a segment of a zero-mean, stationary, filtered Gaussian white noise random process, represented by its power spectrum. All possible seismic hazards at a site, represented by a hazard curve, are also included in the analysis. The soil-foundation system is represented by a rigid surface foundation on an elastic halfspace. Random and other uncertainties in the strength properties of the structure, in the stiffness and internal damping of the soil, are also included in the analysis. Finally, a realistic reinforced concrete containment is analyzed to demonstrate the application of the method. For this containment, the soil-structure interaction effects on; (1) limit state probabilities, (2) structural fragility curves, (3) floor response spectra with probabilistic content, and (4) correlation coefficients for total acceleration response at specified structural locations, are examined in detail. 25 refs., 21 figs., 12 tabs
Position Mooring Control Based on a Structural Reliability Criterion
DEFF Research Database (Denmark)
Fang, Shaoji; Leira, Bernt J.; Blanke, Mogens
2013-01-01
is achieved using structural reliability indices in a cost function, where both the mean mooring-line tension and dynamic effects are considered. An optimal set-point is automatically produced without need for manual interaction. The parameters of the extreme value distribution are calculated on-line thereby...... mooring lines simultaneously from exceeding a stress threshold, this paper suggests a new algorithm to determine the reference position and an associated control system. The safety of each line is assessed through a structural reliability index. A reference position where all mooring lines are safe...
Reliability analysis of structures under periodic proof tests in service
Yang, J.-N.
1976-01-01
A reliability analysis of structures subjected to random service loads and periodic proof tests treats gust loads and maneuver loads as random processes. Crack initiation, crack propagation, and strength degradation are treated as the fatigue process. The time to fatigue crack initiation and ultimate strength are random variables. Residual strength decreases during crack propagation, so that failure rate increases with time. When a structure fails under periodic proof testing, a new structure is built and proof-tested. The probability of structural failure in service is derived from treatment of all the random variables, strength degradations, service loads, proof tests, and the renewal of failed structures. Some numerical examples are worked out.
Durability reliability analysis for corroding concrete structures under uncertainty
Zhang, Hao
2018-02-01
This paper presents a durability reliability analysis of reinforced concrete structures subject to the action of marine chloride. The focus is to provide insight into the role of epistemic uncertainties on durability reliability. The corrosion model involves a number of variables whose probabilistic characteristics cannot be fully determined due to the limited availability of supporting data. All sources of uncertainty, both aleatory and epistemic, should be included in the reliability analysis. Two methods are available to formulate the epistemic uncertainty: the imprecise probability-based method and the purely probabilistic method in which the epistemic uncertainties are modeled as random variables. The paper illustrates how the epistemic uncertainties are modeled and propagated in the two methods, and shows how epistemic uncertainties govern the durability reliability.
Structural Reliability Aspects in Design of Wind Turbines
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
2007-01-01
Reliability assessment, optimal design and optimal operation and maintenance of wind turbines are an area of significant interest for the fast growing wind turbine industry for sustainable production of energy. Offshore wind turbines in wind farms give special problems due to wake effects inside...... the farm. Reliability analysis and optimization of wind turbines require that the special conditions for wind turbine operation are taken into account. Control of the blades implies load reductions for large wind speeds and parking for high wind speeds. In this paper basic structural failure modes for wind...... turbines are described. Further, aspects are presented related to reliability-based optimization of wind turbines, assessment of optimal reliability level and operation and maintenance....
Reliability analysis of offshore structures using OMA based fatigue stresses
DEFF Research Database (Denmark)
Silva Nabuco, Bruna; Aissani, Amina; Glindtvad Tarpø, Marius
2017-01-01
focus is on the uncertainty observed on the different stresses used to predict the damage. This uncertainty can be reduced by Modal Based Fatigue Monitoring which is a technique based on continuously measuring of the accelerations in few points of the structure with the use of accelerometers known...... points of the structure, the stress history can be calculated in any arbitrary point of the structure. The accuracy of the estimated actual stress is analyzed by experimental tests on a scale model where the obtained stresses are compared to strain gauges measurements. After evaluating the fatigue...... stresses directly from the operational response of the structure, a reliability analysis is performed in order to estimate the reliability of using Modal Based Fatigue Monitoring for long term fatigue studies....
Structural Reliability Methods for Wind Power Converter System Component Reliability Assessment
DEFF Research Database (Denmark)
Kostandyan, Erik; Sørensen, John Dalsgaard
2012-01-01
Wind power converter systems are essential subsystems in both off-shore and on-shore wind turbines. It is the main interface between generator and grid connection. This system is affected by numerous stresses where the main contributors might be defined as vibration and temperature loadings....... The temperature variations induce time-varying stresses and thereby fatigue loads. A probabilistic model is used to model fatigue failure for an electrical component in the power converter system. This model is based on a linear damage accumulation and physics of failure approaches, where a failure criterion...... is defined by the threshold model. The attention is focused on crack propagation in solder joints of electrical components due to the temperature loadings. Structural Reliability approaches are used to incorporate model, physical and statistical uncertainties. Reliability estimation by means of structural...
Reliability Based Calibration of Fatigue Design Guidelines for Ship Structures
DEFF Research Database (Denmark)
Folsø, Rasmus; Otto, S.; Parmentier, G.
2002-01-01
A simple reliability based framework is applied to calibrate a new set of fatigue design guidelines. This new guideline considers two different approaches for the assessment of both loads, stresses and local stress raising effects, and partial safety factors must be given for any combination...
Development on methods for evaluating structure reliability of piping components
International Nuclear Information System (INIS)
Schimpfke, T.; Grebner, H.; Peschke, J.; Sievers, J.
2003-01-01
In the frame of the German reactor safety research program of the Federal Ministry of Economics and Labour, GRS has started to develop an analysis code named PROST (PRObabilistic STructure analysis) for estimating the leak and break probabilities of piping systems in nuclear power plants. The development is based on the experience achieved with applications of the public available US code PRAISE 3.10 (Piping Reliability Analysis Including Seismic Events), which was supplemented by additional features regarding the statistical evaluation and the crack orientation. PROST is designed to be more flexible to changes and supplementations. Up to now it can be used for calculating fatigue problems. The paper mentions the main capabilities and theoretical background of the present PROST development and presents a parametric study on the influence by changing the method of stress intensity factor and limit load calculation and the statistical evaluation options on the leak probability of an exemplary pipe with postulated axial crack distribution. Furthermore the resulting leak probability of an exemplary pipe with postulated circumferential crack distribution is compared with the results of the modified PRAISE computer program. The intention of this investigation is to show trends. Therefore the resulting absolute values for probabilities should not be considered as realistic evaluations. (author)
Condon, David; Revelle, William
2017-01-01
Separating the signal in a test from the irrelevant noise is a challenge for all measurement. Low test reliability limits test validity, attenuates important relationships, and can lead to regression artifacts. Multiple approaches to the assessment and improvement of reliability are discussed. The advantages and disadvantages of several different approaches to reliability are considered. Practical advice on how to assess reliability using open source software is provided.
The Seismic Reliability of Offshore Structures Based on Nonlinear Time History Analyses
International Nuclear Information System (INIS)
Hosseini, Mahmood; Karimiyani, Somayyeh; Ghafooripour, Amin; Jabbarzadeh, Mohammad Javad
2008-01-01
Regarding the past earthquakes damages to offshore structures, as vital structures in the oil and gas industries, it is important that their seismic design is performed by very high reliability. Accepting the Nonlinear Time History Analyses (NLTHA) as the most reliable seismic analysis method, in this paper an offshore platform of jacket type with the height of 304 feet, having a deck of 96 feet by 94 feet, and weighing 290 million pounds has been studied. At first, some Push-Over Analyses (POA) have been preformed to recognize the more critical members of the jacket, based on the range of their plastic deformations. Then NLTHA have been performed by using the 3-components accelerograms of 100 earthquakes, covering a wide range of frequency content, and normalized to three Peak Ground Acceleration (PGA) levels of 0.3 g, 0.65 g, and 1.0 g. By using the results of NLTHA the damage and rupture probabilities of critical member have been studied to assess the reliability of the jacket structure. Regarding that different structural members of the jacket have different effects on the stability of the platform, an ''importance factor'' has been considered for each critical member based on its location and orientation in the structure, and then the reliability of the whole structure has been obtained by combining the reliability of the critical members, each having its specific importance factor
Mechanical Properties for Reliability Analysis of Structures in Glassy Carbon
Garion, Cédric
2014-01-01
Despite its good physical properties, the glassy carbon material is not widely used, especially for structural applications. Nevertheless, its transparency to particles and temperature resistance are interesting properties for the applications to vacuum chambers and components in high energy physics. For example, it has been proposed for fast shutter valve in particle accelerator [1] [2]. The mechanical properties have to be carefully determined to assess the reliability of structures in such a material. In this paper, mechanical tests have been carried out to determine the elastic parameters, the strength and toughness on commercial grades. A statistical approach, based on the Weibull’s distribution, is used to characterize the material both in tension and compression. The results are compared to the literature and the difference of properties for these two loading cases is shown. Based on a Finite Element analysis, a statistical approach is applied to define the reliability of a structural component in gl...
Reliability Analysis of Timber Structures through NDT Data Upgrading
DEFF Research Database (Denmark)
Sousa, Hélder; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning
The first part of this document presents, in chapter 2, a description of timber characteristics and common used NDT and MDT for timber elements. Stochastic models for timber properties and damage accumulation models are also referred. According to timber’s properties a framework is proposed...... for a safety reassessment procedure. For that purpose a theoretical background for structural reliability assessment including probabilistic concepts for structural systems and stochastic models are given in chapter 3. System models, both series and parallel systems, are presented as well as methods...... for robustness are dealt in chapter 5. The second part of this document begins in chapter 6, where a practical application of the premise definitions and methodologies is given through the implementation of upgraded models with NDT and MDT data. Structural life-cycle is, therefore, assessed and reliability...
Reliability of structures by using probability and fatigue theories
International Nuclear Information System (INIS)
Lee, Ouk Sub; Kim, Dong Hyeok; Park, Yeon Chang
2008-01-01
Methodologies to calculate failure probability and to estimate the reliability of fatigue loaded structures are developed. The applicability of the methodologies is evaluated with the help of the fatigue crack growth models suggested by Paris and Walker. The probability theories such as the FORM (first order reliability method), the SORM (second order reliability method) and the MCS (Monte Carlo simulation) are utilized. It is found that the failure probability decreases with the increase of the design fatigue life and the applied minimum stress, the decrease of the initial edge crack size, the applied maximum stress and the slope of Paris equation. Furthermore, according to the sensitivity analysis of random variables, the slope of Pairs equation affects the failure probability dominantly among other random variables in the Paris and the Walker models
MEMS Reliability: Infrastructure, Test Structures, Experiments, and Failure Modes
Energy Technology Data Exchange (ETDEWEB)
TANNER,DANELLE M.; SMITH,NORMAN F.; IRWIN,LLOYD W.; EATON,WILLIAM P.; HELGESEN,KAREN SUE; CLEMENT,J. JOSEPH; MILLER,WILLIAM M.; MILLER,SAMUEL L.; DUGGER,MICHAEL T.; WALRAVEN,JEREMY A.; PETERSON,KENNETH A.
2000-01-01
The burgeoning new technology of Micro-Electro-Mechanical Systems (MEMS) shows great promise in the weapons arena. We can now conceive of micro-gyros, micro-surety systems, and micro-navigators that are extremely small and inexpensive. Do we want to use this new technology in critical applications such as nuclear weapons? This question drove us to understand the reliability and failure mechanisms of silicon surface-micromachined MEMS. Development of a testing infrastructure was a crucial step to perform reliability experiments on MEMS devices and will be reported here. In addition, reliability test structures have been designed and characterized. Many experiments were performed to investigate failure modes and specifically those in different environments (humidity, temperature, shock, vibration, and storage). A predictive reliability model for wear of rubbing surfaces in microengines was developed. The root causes of failure for operating and non-operating MEMS are discussed. The major failure mechanism for operating MEMS was wear of the polysilicon rubbing surfaces. Reliability design rules for future MEMS devices are established.
Reliability-based design code calibration for concrete containment structures
International Nuclear Information System (INIS)
Han, B.K.; Cho, H.N.; Chang, S.P.
1991-01-01
In this study, a load combination criteria for design and a probability-based reliability analysis were proposed on the basis of a FEM-based random vibration analysis. The limit state model defined for the study is a serviceability limit state of the crack failure that causes the emission of radioactive materials, and the results are compared with the case of strength limit state. More accurate reliability analyses under various dynamic loads such as earthquake loads were made possible by incorporating the FEM and random vibration theory, which is different from the conventional reliability analysis method. The uncertainties in loads and resistance available in Korea and the references were adapted to the situation of Korea, and especially in case of earthquake, the design earthquake was assessed based on the available data for the probabilistic description of earthquake ground acceleration in the Korea peninsula. The SAP V-2 is used for a three-dimensional finite element analysis of concrete containment structure, and the reliability analysis is carried out by modifying HRAS reliability analysis program for this study. (orig./GL)
Reliability and Hierarchical Structure of DSM-5 Pathological Traits in a Danish Mixed Sample
DEFF Research Database (Denmark)
Bo, Sune; Bach, Bo; Mortensen, Erik Lykke
2016-01-01
In this study we assessed the DSM-5 trait model in a large Danish sample (n = 1,119) with respect to reliability of the applied Danish version of the Personality Inventory for DSM-5 (PID-5) self-report form by means of internal consistency and item discrimination. In addition, we tested whether...... the five-factor structure of the DSM-5 trait model can be replicated in a Danish independent sample using the PID-5 self-report form. Finally, we examined the hierarchical structure of DSM-5 traits. In terms of internal consistency and item discrimination, the applied PID-5 scales were generally found...... reliable and functional; our data resembled the five-factor structure of previous findings, and we identified a hierarchical structure from one to five factors that was conceptually reasonable and corresponded with existing findings. These results support the new DSM-5 trait model and suggest that it can...
Reliability of containment and safety-related structures
International Nuclear Information System (INIS)
Nessim, M.A.
1995-09-01
A research program on Reliability of Containment and Safety-related Structures has been developed and is described in this document. This program is designed to support AECB's regulatory activities aimed at ensuring the safety of these structures. These activities include evaluating submissions by operators and requesting special assessments when necessary. The results of the proposed research will also be useful in revising and enhancing the CSA design standards for containment and safety-related structures. The process of developing the research program started with an information collection and review phase. The sources of information included C-FER's previous work in the area, various recent research publications, regulatory documents and relevant design standards, and a detailed discussion with AECB staff. The second step was to outline the process of reliability evaluation, and identify the required models and parameters. Comparison between the required and available information was used to identify gaps in the state-of-the-art, and the research program was designed to fill these gaps. The program is organized in four major topics, namely: development of an approach for reliability analysis; compilation and development of the required analysis tools; application to specific problems related to design, assessment, maintenance and testing of structures; and testing and validation. It is suggested that the program should be supported by an on-going process of communication and consultation between AECB staff and industry experts. This will lend credibility to the results and facilitate their future application. (author). 1 fig
Modelling and estimating degradation processes with application in structural reliability
International Nuclear Information System (INIS)
Chiquet, J.
2007-06-01
The characteristic level of degradation of a given structure is modeled through a stochastic process called the degradation process. The random evolution of the degradation process is governed by a differential system with Markovian environment. We put the associated reliability framework by considering the failure of the structure once the degradation process reaches a critical threshold. A closed form solution of the reliability function is obtained thanks to Markov renewal theory. Then, we build an estimation methodology for the parameters of the stochastic processes involved. The estimation methods and the theoretical results, as well as the associated numerical algorithms, are validated on simulated data sets. Our method is applied to the modelling of a real degradation mechanism, known as crack growth, for which an experimental data set is considered. (authors)
ZERBERUS - the code for reliability analysis of crack containing structures
International Nuclear Information System (INIS)
Cizelj, L.; Riesch-Oppermann, H.
1992-04-01
Brief description of the First- and Second Order Reliability Methods, being the theoretical background of the code, is given. The code structure is described in detail, with special emphasis to the new application fields. The numerical example investigates failure probability of steam generator tubing affected by stress corrosion cracking. The changes necessary to accommodate this analysis within the ZERBERUS code are explained. Analysis results are compared to different Monte Carlo techniques. (orig./HP) [de
An overview of reliability methods in mechanical and structural design
Wirsching, P. H.; Ortiz, K.; Lee, S. J.
1987-01-01
An evaluation is made of modern methods of fast probability integration and Monte Carlo treatment for the assessment of structural systems' and components' reliability. Fast probability integration methods are noted to be more efficient than Monte Carlo ones. This is judged to be an important consideration when several point probability estimates must be made in order to construct a distribution function. An example illustrating the relative efficiency of the various methods is included.
Time-dependent reliability analysis and condition assessment of structures
International Nuclear Information System (INIS)
Ellingwood, B.R.
1997-01-01
Structures generally play a passive role in assurance of safety in nuclear plant operation, but are important if the plant is to withstand the effect of extreme environmental or abnormal events. Relative to mechanical and electrical components, structural systems and components would be difficult and costly to replace. While the performance of steel or reinforced concrete structures in service generally has been very good, their strengths may deteriorate during an extended service life as a result of changes brought on by an aggressive environment, excessive loading, or accidental loading. Quantitative tools for condition assessment of aging structures can be developed using time-dependent structural reliability analysis methods. Such methods provide a framework for addressing the uncertainties attendant to aging in the decision process
Rapid and reliable protein structure determination via chemical shift threading.
Hafsa, Noor E; Berjanskii, Mark V; Arndt, David; Wishart, David S
2018-01-01
Protein structure determination using nuclear magnetic resonance (NMR) spectroscopy can be both time-consuming and labor intensive. Here we demonstrate how chemical shift threading can permit rapid, robust, and accurate protein structure determination using only chemical shift data. Threading is a relatively old bioinformatics technique that uses a combination of sequence information and predicted (or experimentally acquired) low-resolution structural data to generate high-resolution 3D protein structures. The key motivations behind using NMR chemical shifts for protein threading lie in the fact that they are easy to measure, they are available prior to 3D structure determination, and they contain vital structural information. The method we have developed uses not only sequence and chemical shift similarity but also chemical shift-derived secondary structure, shift-derived super-secondary structure, and shift-derived accessible surface area to generate a high quality protein structure regardless of the sequence similarity (or lack thereof) to a known structure already in the PDB. The method (called E-Thrifty) was found to be very fast (often chemical shift refinement, these results suggest that protein structure determination, using only NMR chemical shifts, is becoming increasingly practical and reliable. E-Thrifty is available as a web server at http://ethrifty.ca .
DEFF Research Database (Denmark)
Dimitrov, Nikolay Krasimirov; Friis-Hansen, Peter; Berggreen, Christian
2013-01-01
by the composite failure criteria. Each failure mode has been considered in a separate component reliability analysis, followed by a system analysis which gives the total probability of failure of the structure. The Model Correction Factor method used in connection with FORM (First-Order Reliability Method) proved...
Design of a composite structure to achieve a specified reliability level
International Nuclear Information System (INIS)
Boyer, C.; Beakou, A.; Lemaire, M.
1997-01-01
Safety factors are widely used in structural design. For composite material structures, however, the lack of experimental feed-back does not allow the use of safety factors optimized from cost and reliability point of view. Reliability methods are one way to achieve the calibration of partial safety factors using a more rational method than judgement alone. First we present the calibration process. The reliability methods FORM, SORM, simulation, are initially applied to a laminate plate under uniform pressure. In this example, we compare three design criteria; the different reliability methods agree with the reference method for all criteria used. We chose the Tsai-Hill criteria and the FORM method to calculate safety factors. Then, a calibration process is undertaken on a composite pipe and this serves to illustrate the different steps in the calculation. Finally, we present a calibration of a general plate structure. The partial safety factors and their sensitivities to the different parameters of the stochastic variables are given according to load type
Reliability-Based Structural Optimization of Wave Energy Converters
DEFF Research Database (Denmark)
Ambühl, Simon; Kramer, Morten; Sørensen, John Dalsgaard
2014-01-01
More and more wave energy converter (WEC) concepts are reaching prototype level. Once the prototype level is reached, the next step in order to further decrease the levelized cost of energy (LCOE) is optimizing the overall system with a focus on structural and maintenance (inspection) costs......, as well as on the harvested power from the waves. The target of a fully-developed WEC technology is not maximizing its power output, but minimizing the resulting LCOE. This paper presents a methodology to optimize the structural design of WECs based on a reliability-based optimization problem...
High-Reliable PLC RTOS Development and RPS Structure Analysis
Energy Technology Data Exchange (ETDEWEB)
Sohn, H. S.; Song, D. Y.; Sohn, D. S.; Kim, J. H. [Enersys Co., Daejeon (Korea, Republic of)
2008-04-15
One of the KNICS objectives is to develop a platform for Nuclear Power Plant(NPP) I and C(Instrumentation and Control) system, especially plant protection system. The developed platform is POSAFE-Q and this work supports the development of POSAFE-Q with the development of high-reliable real-time operating system(RTOS) and programmable logic device(PLD) software. Another KNICS objective is to develop safety I and C systems, such as Reactor Protection System(RPS) and Engineered Safety Feature-Component Control System(ESF-CCS). This work plays an important role in the structure analysis for RPS. Validation and verification(V and V) of the safety critical software is an essential work to make digital plant protection system highly reliable and safe. Generally, the reliability and safety of software based system can be improved by strict quality assurance framework including the software development itself. In other words, through V and V, the reliability and safety of a system can be improved and the development activities like software requirement specification, software design specification, component tests, integration tests, and system tests shall be appropriately documented for V and V.
High-Reliable PLC RTOS Development and RPS Structure Analysis
International Nuclear Information System (INIS)
Sohn, H. S.; Song, D. Y.; Sohn, D. S.; Kim, J. H.
2008-04-01
One of the KNICS objectives is to develop a platform for Nuclear Power Plant(NPP) I and C(Instrumentation and Control) system, especially plant protection system. The developed platform is POSAFE-Q and this work supports the development of POSAFE-Q with the development of high-reliable real-time operating system(RTOS) and programmable logic device(PLD) software. Another KNICS objective is to develop safety I and C systems, such as Reactor Protection System(RPS) and Engineered Safety Feature-Component Control System(ESF-CCS). This work plays an important role in the structure analysis for RPS. Validation and verification(V and V) of the safety critical software is an essential work to make digital plant protection system highly reliable and safe. Generally, the reliability and safety of software based system can be improved by strict quality assurance framework including the software development itself. In other words, through V and V, the reliability and safety of a system can be improved and the development activities like software requirement specification, software design specification, component tests, integration tests, and system tests shall be appropriately documented for V and V.
Structuring factoring business: accounting aspects
Directory of Open Access Journals (Sweden)
I.M. Vygivska
2017-08-01
Full Text Available The article theoretically substantiates the fact that factoring belongs to the main operational activity of a factoring company, and this allowed structuring the factoring business by types of activity. The lack of a unified approach to the classification of factoring (factoring services made it possible to systematize and refine their classification as a basis for developing accounting and analytical support for risk management of factoring business. The authors single out such classification signs as: the right of the reverse claim (reverse, irretrievable, a territorial feature (international, internal, the subject of the factoring contract (real, consensual, the availability of notification of the debtor (conventional, confidential. The structuring of factoring business contributes to the identification of the risks of the economic activities of a factoring company depending on the type of factoring, the development of methodological support for the bookkeeping of factoring transactions in a risk environment, the search for risk management practices and the determination of management effectiveness in general.
Directory of Open Access Journals (Sweden)
Shujuan Wang
2015-01-01
Full Text Available This paper investigates the structural design optimization to cover both the reliability and robustness under uncertainty in design variables. The main objective is to improve the efficiency of the optimization process. To address this problem, a hybrid reliability-based robust design optimization (RRDO method is proposed. Prior to the design optimization, the Sobol sensitivity analysis is used for selecting key design variables and providing response variance as well, resulting in significantly reduced computational complexity. The single-loop algorithm is employed to guarantee the structural reliability, allowing fast optimization process. In the case of robust design, the weighting factor balances the response performance and variance with respect to the uncertainty in design variables. The main contribution of this paper is that the proposed method applies the RRDO strategy with the usage of global approximation and the Sobol sensitivity analysis, leading to the reduced computational cost. A structural example is given to illustrate the performance of the proposed method.
Validity and factor structure of the bodybuilding dependence scale
Smith, D; Hale, B
2004-01-01
Objectives: To investigate the factor structure, validity, and reliability of the bodybuilding dependence scale and to investigate differences in bodybuilding dependence between men and women and competitive and non-competitive bodybuilders.
Reliability-Based Structural Optimization of Wave Energy Converters
Directory of Open Access Journals (Sweden)
Simon Ambühl
2014-12-01
Full Text Available More and more wave energy converter (WEC concepts are reaching prototypelevel. Once the prototype level is reached, the next step in order to further decrease thelevelized cost of energy (LCOE is optimizing the overall system with a focus on structuraland maintenance (inspection costs, as well as on the harvested power from the waves.The target of a fully-developed WEC technology is not maximizing its power output,but minimizing the resulting LCOE. This paper presents a methodology to optimize thestructural design of WECs based on a reliability-based optimization problem and the intentto maximize the investor’s benefits by maximizing the difference between income (e.g., fromselling electricity and the expected expenses (e.g., structural building costs or failure costs.Furthermore, different development levels, like prototype or commercial devices, may havedifferent main objectives and will be located at different locations, as well as receive varioussubsidies. These points should be accounted for when performing structural optimizationsof WECs. An illustrative example on the gravity-based foundation of the Wavestar deviceis performed showing how structural design can be optimized taking target reliability levelsand different structural failure modes due to extreme loads into account.
Reliability-based inspection of prestressed concrete containment structures
International Nuclear Information System (INIS)
Pandey, M.D.
1996-03-01
A study was undertaken to develop a reliability-based approach to the planning of inspection programs for prestressed concrete containment structures. The main function of the prestressing system is to ensure the leak integrity of the containment by maintaining a compressive state of stress under the tensile forces which arise in a hypothesized loss of coolant accident. Prestressing force losses (due to creep and shrinkage, stress relaxation or tendon corrosion) can lead to tensile stresses under accident pressure, resulting in loss of containment leak integrity due to concrete cracking and tensile yielding of the non-prestressed reinforcement. Therefore, the evaluation of prestressing inspection programs was based on their effectiveness in maintaining an acceptable reliability level with respect to a limit state representing yeilding of non-prestressed reinforcement. An annual target reliability of 10 -4 was used for this limit state. As specified in CSA-N287.7, the evaluation of prestressing systems for containment structures is based on the results of lift-off tests to determine the prestressing force. For unbonded systems the tests are carried out on a randomly selected sample from each tendon group in the structure. For bonded systems, the test is carried out on an unbonded test beam that matches the section geometry and material properties of the containment structure. It was found that flexural testing is useful in updating the probability of concrete cracking under accident pressure. For unbonded systems, the analysis indicated that the sample size recommended by the CSA Standard (4% of the tendon population) is adequate. The CSA recommendation for a five year inspection interval is conservative unless severe degradation of the prestressing system, characterized by a high prestressing loss rate (>3%) and a large coefficient of variation of the measured prestressing force (>15%), is observed
Directory of Open Access Journals (Sweden)
Xingfa Yang
2018-01-01
Full Text Available Nondeterministic parameters of certain distribution are employed to model structural uncertainties, which are usually assumed as stochastic factors. However, model parameters may not be precisely represented due to some factors in engineering practices, such as lack of sufficient data, data with fuzziness, and unknown-but-bounded conditions. To this end, interval and fuzzy parameters are implemented and an efficient approach to structural reliability analysis with random-interval-fuzzy hybrid parameters is proposed in this study. Fuzzy parameters are first converted to equivalent random ones based on the equal entropy principle. 3σ criterion is then employed to transform the equivalent random and the original random parameters to interval variables. In doing this, the hybrid reliability problem is transformed into the one only with interval variables, in other words, nonprobabilistic reliability analysis problem. Nevertheless, the problem of interval extension existed in interval arithmetic, especially for the nonlinear systems. Therefore, universal grey mathematics, which can tackle the issue of interval extension, is employed to solve the nonprobabilistic reliability analysis problem. The results show that the proposed method can obtain more conservative results of the hybrid structural reliability.
Reliability updating based on monitoring of structural response parameters
International Nuclear Information System (INIS)
Leira, B.J.
2016-01-01
Short- and long-term aspects of measuring structural response parameters are addressed. Two specific examples of such measurements are considered for the purpose of illustration and in order to focus the discussion. These examples are taken from the petroleum industry (monitoring of riser response) and from the shipping industry (monitoring of ice-induced strains in a ship hull). Similarities and differences between the two cases are elaborated with respect to which are the most relevant mechanical limit states. Furthermore, main concerns related to reliability levels within a short-term versus long-term time horizon are highlighted. Quantifying the economic benefits of applying monitoring systems is also addressed. - Highlights: • Two examples of structural response monitoring are described. • Application of measurements is discussed in relation to updating of load and structural parameters. • Quantification of the value of response monitoring is made for both of the examples.
Spinal appearance questionnaire: factor analysis, scoring, reliability, and validity testing.
Carreon, Leah Y; Sanders, James O; Polly, David W; Sucato, Daniel J; Parent, Stefan; Roy-Beaudry, Marjolaine; Hopkins, Jeffrey; McClung, Anna; Bratcher, Kelly R; Diamond, Beverly E
2011-08-15
Cross sectional. This study presents the factor analysis of the Spinal Appearance Questionnaire (SAQ) and its psychometric properties. Although the SAQ has been administered to a large sample of patients with adolescent idiopathic scoliosis (AIS) treated surgically, its psychometric properties have not been fully evaluated. This study presents the factor analysis and scoring of the SAQ and evaluates its psychometric properties. The SAQ and the Scoliosis Research Society-22 (SRS-22) were administered to AIS patients who were being observed, braced or scheduled for surgery. Standard demographic data and radiographic measures including Lenke type and curve magnitude were also collected. Of the 1802 patients, 83% were female; with a mean age of 14.8 years and mean initial Cobb angle of 55.8° (range, 0°-123°). From the 32 items of the SAQ, 15 loaded on two factors with consistent and significant correlations across all Lenke types. There is an Appearance (items 1-10) and an Expectations factor (items 12-15). Responses are summed giving a range of 5 to 50 for the Appearance domain and 5 to 20 for the Expectations domain. The Cronbach's α was 0.88 for both domains and Total score with a test-retest reliability of 0.81 for Appearance and 0.91 for Expectations. Correlations with major curve magnitude were higher for the SAQ Appearance and SAQ Total scores compared to correlations between the SRS Appearance and SRS Total scores. The SAQ and SRS-22 Scores were statistically significantly different in patients who were scheduled for surgery compared to those who were observed or braced. The SAQ is a valid measure of self-image in patients with AIS with greater correlation to curve magnitude than SRS Appearance and Total score. It also discriminates between patients who require surgery from those who do not.
Directory of Open Access Journals (Sweden)
Hai An
2016-08-01
Full Text Available Aiming to resolve the problems of a variety of uncertainty variables that coexist in the engineering structure reliability analysis, a new hybrid reliability index to evaluate structural hybrid reliability, based on the random–fuzzy–interval model, is proposed in this article. The convergent solving method is also presented. First, the truncated probability reliability model, the fuzzy random reliability model, and the non-probabilistic interval reliability model are introduced. Then, the new hybrid reliability index definition is presented based on the random–fuzzy–interval model. Furthermore, the calculation flowchart of the hybrid reliability index is presented and it is solved using the modified limit-step length iterative algorithm, which ensures convergence. And the validity of convergent algorithm for the hybrid reliability model is verified through the calculation examples in literature. In the end, a numerical example is demonstrated to show that the hybrid reliability index is applicable for the wear reliability assessment of mechanisms, where truncated random variables, fuzzy random variables, and interval variables coexist. The demonstration also shows the good convergence of the iterative algorithm proposed in this article.
Structural reliability analysis applied to pipeline risk analysis
Energy Technology Data Exchange (ETDEWEB)
Gardiner, M. [GL Industrial Services, Loughborough (United Kingdom); Mendes, Renato F.; Donato, Guilherme V.P. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)
2009-07-01
Quantitative Risk Assessment (QRA) of pipelines requires two main components to be provided. These are models of the consequences that follow from some loss of containment incident, and models for the likelihood of such incidents occurring. This paper describes how PETROBRAS have used Structural Reliability Analysis for the second of these, to provide pipeline- and location-specific predictions of failure frequency for a number of pipeline assets. This paper presents an approach to estimating failure rates for liquid and gas pipelines, using Structural Reliability Analysis (SRA) to analyze the credible basic mechanisms of failure such as corrosion and mechanical damage. SRA is a probabilistic limit state method: for a given failure mechanism it quantifies the uncertainty in parameters to mathematical models of the load-resistance state of a structure and then evaluates the probability of load exceeding resistance. SRA can be used to benefit the pipeline risk management process by optimizing in-line inspection schedules, and as part of the design process for new construction in pipeline rights of way that already contain multiple lines. A case study is presented to show how the SRA approach has recently been used on PETROBRAS pipelines and the benefits obtained from it. (author)
Reliability of ultrasound for measurement of selected foot structures.
Crofts, G; Angin, S; Mickle, K J; Hill, S; Nester, C J
2014-01-01
Understanding the relationship between the lower leg muscles, foot structures and function is essential to explain how disease or injury may relate to changes in foot function and clinical pathology. The aim of this study was to investigate the inter-operator reliability of an ultrasound protocol to quantify features of: rear, mid and forefoot sections of the plantar fascia (PF); flexor hallucis brevis (FHB); flexor digitorum brevis (FDB); abductor hallucis (AbH); flexor digitorum longus (FDL); flexor hallucis longus (FHL); tibialis anterior (TA); and peroneus longus and brevis (PER). A sample of 6 females and 4 males (mean age 29.1 ± 7.2 years, mean BMI 25.5 ± 4.8) was recruited from a university student and staff population. Scans were obtained using a portable Venue 40 musculoskeletal ultrasound system (GE Healthcare UK) with a 5-13 MHz wideband linear array probe with a 12.7 mm × 47.1mm footprint by two operators in the same scanning session. Intraclass Correlation Coefficients (ICC) values for muscle thickness (ICC range 0.90-0.97), plantar fascia thickness (ICC range 0.94-0.98) and cross sectional muscle measurements (ICC range 0.91-0.98) revealed excellent inter-operator reliability. The limits of agreement, relative to structure size, ranged from 9.0% to 17.5% for muscle thickness, 11.0-18.0% for plantar fascia, and 11.0-26.0% for cross sectional area measurements. The ultrasound protocol implemented in this work has been shown to be reliable. It therefore offers the opportunity to quantify the structures concerned and better understand their contributions to foot function. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.
Reliability-Based Inspection Planning for Structural Systems
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
1993-01-01
A general model for reliability-based optimal inspection and repair strategies for structural systems is described. The total expected costs in the design lifetime is minimized with the number of inspections, the inspection times and efforts as decision variables. The equivalence of this model...... with a preposterior analysis from statistical decision theory is discussed. It is described how information obtained by an inspection can be used in a repair decision. Stochastic models for inspection, measurement and repair actions are presented. The general model is applied for inspection and repair planning...
Out Brief for the Structural Reliability Partnership Workshop
Energy Technology Data Exchange (ETDEWEB)
Boyce, Brad [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fang, Eliot [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kolski, Alyssa [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zimmerman, Jonathan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Furmanski, Jevan [Exxon Mobil, Annandale, NJ (United States); Ravi-Chandar, Krishnaswamy [Univ. of Texas, Austin, TX (United States)
2017-08-30
The Structural Reliability Partnership Workshop was held in Albuquerque, NM on August 29-30, 2017 and was hosted by Sandia National Laboratories. Attendees were present from academia, industry and several other national laboratories. The workshop kicked off with an introduction to the SRP to familiarize potential members with what the purpose, structure and benefits would be to their organization. Technical overviews were given on several topics by attendees from each sector – national labs, universities and industry – to provide a snapshot of the type of work that is currently being conducted on structural reliability. Attendees were then given the opportunity to suggest and discuss potential Challenge Scenario topics. Three were ultimately decided upon as being the most important: Additive Manufacturing, Hydrogen Pipeline Steels, and Bolted Joined Structures. These were then analyzed using Quad Charts to determine What, How, Who, and Why these areas would be further investigated. Rather than restricting future research to only one area, the option was left open to investigate both the top two, depending on interest and cost associated with hosting such an event. More informal collaboration may be undertaken for the third topic if members have time and interest. Other items discussed pertained to the organization, structure and policies of the Partnership. Topics including Data Management, IP, and mechanisms of partnering/information sharing were touched upon but final decisions were not made. Further action is needed before this can be done. Action items were outlined and assigned, where possible. The next workshop is to be held in early August 2018 in Boulder, CO and is to be hosted by NIST. In the interim, quarterly updates are to take place via WebEx to maintain a line of communication and to ensure progress on both the administrative and technical tasks.
Simulator training and human factor reliability in Kozloduy NPP, Bulgaria
International Nuclear Information System (INIS)
Stoychev, Kosta
2007-01-01
This is a PowerPoint presentation. Situated in North Bulgaria, in the vicinity of the town of Kozloduy, near the Danube River bank, there is the Bulgarian Kozloduy Nuclear Power plant operating four WWER-440 and two WWER-1000 units. Units 1 and 2 were commissioned in July, 1974 and November, 1975, respectively. These were shut down at the end of 2003. Units 3 and 4 were commissioned in December, 1980 and May, 1982. They were shut down at the end of 2006 as a precondition for Bulgaria's accession to the European Union. The 1000 MW units 5 and 6 of Kozloduy NPP were commissioned in September, 1988 and December, 1993, respectively. Large-scale modernization have been implemented and now the units meet all international safety standards. The paper describes the multifunctional simulator Kozloduy NPP for the operational staff training. The training stages are as follows: - Preparatory; -Theoretical studies; - Training at the Training Centre by means of technical devices; - Preparation and sitting for an exam before a Kozloduy NPP expert commission; - Simulator training ; - Preparation to obtain a permit for a license, corresponding to the position to begin work at the NPP; - Exams before the Nuclear Regulatory Agency (NRA) and licensing; - Shadow training at the working place; - Permission for unaided operation. The following positions are addressed by the simulator training: - Chief Plant Supervisor; - Shift Unit Supervisor; - Senior Reactor Operator; - Simulator Instructor; - Controller physicist; -Senior Turbine Operator; - Senior Operator of Turbine Feedwater Pumps of Kozloduy NPP. Improving of training method led to a reduction of number of significant events while worldwide practice proves that improvement of engineering resulted in an increase in the percentage of events, related to human factor. Analysis of human reliability in 2005 and 2006 in cooperation with representatives from Great Britain and the Technical University in Sofia were worked on the DTI NSP B
Factor structure and psychometric properties of the General Health ...
African Journals Online (AJOL)
Purpose: There is little information about the reliability and validity of the 12-item General Health Questionnaire (GHQ-12) in Ghana. This study sought to examine the reliability and factor structure of the GHQ-12 in Ghanaian adolescents. Methods: High school students (N = 770) completed the GHQ-12 and the Adolescent ...
Analysis of NPP protection structure reliability under impact of a falling aircraft
International Nuclear Information System (INIS)
Shul'man, G.S.
1996-01-01
Methodology for evaluation of NPP protection structure reliability by impact of aircraft fall down is considered. The methodology is base on the probabilistic analysis of all potential events. The problem is solved in three stages: determination of loads on structural units, calculation of local reliability of protection structures by assigned loads and estimation of the structure reliability. The methodology proposed may be applied at the NPP design stage and by determination of reliability of already available structures
Reliability-Based Optimal Design for Very Large Floating Structure
Institute of Scientific and Technical Information of China (English)
ZHANG Shu-hua(张淑华); FUJIKUBO Masahiko
2003-01-01
Costs and losses induced by possible future extreme environmental conditions and difficulties in repairing post-yielding damage strongly suggest the need for proper consideration in design rather than just life loss prevention. This can be addressed through the development of design methodology that balances the initial cost of the very large floating structure (VLFS) against the expected potential losses resulting from future extreme wave-induced structural damage. Here, the development of a methodology for determining optimal, cost-effective design will be presented and applied to a VLFS located in the Tokyo bay. Optimal design criteria are determined based on the total expected life-cycle cost and acceptable damage probability and curvature of the structure, and a set of sizes of the structure are obtained. The methodology and applications require expressions of the initial cost and the expected life-cycle damage cost as functions of the optimal design variables. This study includes the methodology, total life-cycle cost function, structural damage modeling, and reliability analysis.
Mechanical factors affecting reliability of pressure components (fatigue, cracking)
International Nuclear Information System (INIS)
Lebey, J.; Garnier, C.; Roche, R.; Barrachin, B.
1978-01-01
The reliability of a pressure component can be seriously affected by the formation and development of cracks. The experimental studies presented in this paper are devoted to three different aspects of crack propagation phenomena which have been relatively little described. In close connection with safety analyses of PWR, the authors study the influence of the environment by carrying out fatigue tests with samples bathed in hot pressurized water. Ferritic, austenitic and Incolloy 800 steels were used and the results are presented in the form of fatigue curves in the oligocyclic region. The second part of the paper relates to crack initiation cirteria in ductile steels weakened by notches. The CT samples used make it possible to study almost all types of fracture (ductile, intermediate and brittle). The use of two criteria based on the load limit and on the toughness of the material constitutes a practical way of evaluating crack propagation conditions. A series of tests carried out on notched spherical vessels of different size shows that large vessels are relatively brittle; fast unstable fracture is observed as size increases. Crack growth rate in PWR primary circuits (3/6 steel) is studied on piping elements (0.25 scale) subjected to cyclic stress variations (285 0 C and with pressure varying between 1 and 160 bar in each cycle). By calculating the stress intensity factor, correlation with results obtained in the laboratory on CT samples is possible. (author)
Reliability Analysis of Tubular Joints in Offshore Structures
DEFF Research Database (Denmark)
Thoft-Christensen, Palle; Sørensen, John Dalsgaard
1987-01-01
Reliability analysis of single tubular joints and offshore platforms with tubular joints is" presented. The failure modes considered are yielding, punching, buckling and fatigue failure. Element reliability as well as systems reliability approaches are used and illustrated by several examples....... Finally, optimal design of tubular.joints with reliability constraints is discussed and illustrated by an example....
A damage mechanics based approach to structural deterioration and reliability
Energy Technology Data Exchange (ETDEWEB)
Bhattcharya, B.; Ellingwood, B. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering
1998-02-01
Structural deterioration often occurs without perceptible manifestation. Continuum damage mechanics defines structural damage in terms of the material microstructure, and relates the damage variable to the macroscopic strength or stiffness of the structure. This enables one to predict the state of damage prior to the initiation of a macroscopic flaw, and allows one to estimate residual strength/service life of an existing structure. The accumulation of damage is a dissipative process that is governed by the laws of thermodynamics. Partial differential equations for damage growth in terms of the Helmholtz free energy are derived from fundamental thermodynamical conditions. Closed-form solutions to the equations are obtained under uniaxial loading for ductile deformation damage as a function of plastic strain, for creep damage as a function of time, and for fatigue damage as function of number of cycles. The proposed damage growth model is extended into the stochastic domain by considering fluctuations in the free energy, and closed-form solutions of the resulting stochastic differential equation are obtained in each of the three cases mentioned above. A reliability analysis of a ring-stiffened cylindrical steel shell subjected to corrosion, accidental pressure, and temperature is performed.
A damage mechanics based approach to structural deterioration and reliability
International Nuclear Information System (INIS)
Bhattcharya, B.; Ellingwood, B.
1998-02-01
Structural deterioration often occurs without perceptible manifestation. Continuum damage mechanics defines structural damage in terms of the material microstructure, and relates the damage variable to the macroscopic strength or stiffness of the structure. This enables one to predict the state of damage prior to the initiation of a macroscopic flaw, and allows one to estimate residual strength/service life of an existing structure. The accumulation of damage is a dissipative process that is governed by the laws of thermodynamics. Partial differential equations for damage growth in terms of the Helmholtz free energy are derived from fundamental thermodynamical conditions. Closed-form solutions to the equations are obtained under uniaxial loading for ductile deformation damage as a function of plastic strain, for creep damage as a function of time, and for fatigue damage as function of number of cycles. The proposed damage growth model is extended into the stochastic domain by considering fluctuations in the free energy, and closed-form solutions of the resulting stochastic differential equation are obtained in each of the three cases mentioned above. A reliability analysis of a ring-stiffened cylindrical steel shell subjected to corrosion, accidental pressure, and temperature is performed
Reliability algorithms applied to reinforced concrete structures durability assessment
Directory of Open Access Journals (Sweden)
C. G. Nogueira
Full Text Available This paper addresses the analysis of probabilistic corrosion time initiation in reinforced concrete structures exposed to ions chloride penetration. Structural durability is an important criterion which must be evaluated in every type of structure, especially when these structures are constructed in aggressive atmospheres. Considering reinforced concrete members, chloride diffusion process is widely used to evaluate the durability. Therefore, at modelling this phenomenon, corrosion of reinforcements can be better estimated and prevented. These processes begin when a threshold level of chlorides concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in the literature, deterministic approaches fail to predict accurately the corrosion time initiation due to the inherently randomness observed in this process. In this regard, the durability can be more realistically represented using probabilistic approaches. A probabilistic analysis of ions chloride penetration is presented in this paper. The ions chloride penetration is simulated using the Fick's second law of diffusion. This law represents the chloride diffusion process, considering time dependent effects. The probability of failure is calculated using Monte Carlo simulation and the First Order Reliability Method (FORM with a direct coupling approach. Some examples are considered in order to study these phenomena and a simplified method is proposed to determine optimal values for concrete cover.
Fan, Xiao-Ning; Zhi, Bo
2017-07-01
Uncertainties in parameters such as materials, loading, and geometry are inevitable in designing metallic structures for cranes. When considering these uncertainty factors, reliability-based design optimization (RBDO) offers a more reasonable design approach. However, existing RBDO methods for crane metallic structures are prone to low convergence speed and high computational cost. A unilevel RBDO method, combining a discrete imperialist competitive algorithm with an inverse reliability strategy based on the performance measure approach, is developed. Application of the imperialist competitive algorithm at the optimization level significantly improves the convergence speed of this RBDO method. At the reliability analysis level, the inverse reliability strategy is used to determine the feasibility of each probabilistic constraint at each design point by calculating its α-percentile performance, thereby avoiding convergence failure, calculation error, and disproportionate computational effort encountered using conventional moment and simulation methods. Application of the RBDO method to an actual crane structure shows that the developed RBDO realizes a design with the best tradeoff between economy and safety together with about one-third of the convergence speed and the computational cost of the existing method. This paper provides a scientific and effective design approach for the design of metallic structures of cranes.
Reliability analysis of large scaled structures by optimization technique
International Nuclear Information System (INIS)
Ishikawa, N.; Mihara, T.; Iizuka, M.
1987-01-01
This paper presents a reliability analysis based on the optimization technique using PNET (Probabilistic Network Evaluation Technique) method for the highly redundant structures having a large number of collapse modes. This approach makes the best use of the merit of the optimization technique in which the idea of PNET method is used. The analytical process involves the minimization of safety index of the representative mode, subjected to satisfaction of the mechanism condition and of the positive external work. The procedure entails the sequential performance of a series of the NLP (Nonlinear Programming) problems, where the correlation condition as the idea of PNET method pertaining to the representative mode is taken as an additional constraint to the next analysis. Upon succeeding iterations, the final analysis is achieved when a collapse probability at the subsequent mode is extremely less than the value at the 1st mode. The approximate collapse probability of the structure is defined as the sum of the collapse probabilities of the representative modes classified by the extent of correlation. Then, in order to confirm the validity of the proposed method, the conventional Monte Carlo simulation is also revised by using the collapse load analysis. Finally, two fairly large structures were analyzed to illustrate the scope and application of the approach. (orig./HP)
Reliability prediction of large fuel cell stack based on structure stress analysis
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.
A physical review on power system reliability factors
International Nuclear Information System (INIS)
Navid, Taghizadegan; Ahmad Reza, Zentabchi; Mohammad Ali, Tavakoli; Nader, Samsunchi; Mohammad Ali, Tavakoli
2005-01-01
Full text : Planning and design engineers and management must necessarily take into consideration the funds available, the requirements of regulatory agencies and other restrictions that may be imposed, as well as availability of equipment and supplies. A well-designed electrical power system strikes a reasonable between reliability and cost. A prime responsibility of power system operators is to operate their systems in such a way that will provide the maximum reliability of service possible with the facilities under their control
De Wilde, Katrien Sophie; Tency, Inge; Boudrez, Hedwig; Temmerman, Marleen; Maes, Lea; Clays, Els
2016-06-01
Smoking during pregnancy can cause several maternal and neonatal health risks, yet a considerable number of pregnant women continue to smoke. The objectives of this study were to test the factorial structure, validity and reliability of the Dutch version of the Modified Reasons for Smoking Scale (MRSS) in a sample of smoking pregnant women and to understand reasons for continued smoking during pregnancy. A longitudinal design was performed. Data of 97 pregnant smokers were collected during prenatal consultation. Structural equation modelling was performed to assess the construct validity of the MRSS: an exploratory factor analysis was conducted, followed by a confirmatory factor analysis.Test-retest reliability (addiction, pleasure, habit and social function. Results for internal consistency and test-retest reliability were good to acceptable. There were significant associations of nicotine dependence with tension reduction and addiction and of daily consumption with addiction and habit. Validity and reliability of the MRSS were shown in a sample of pregnant smokers. Tension reduction was the most important reason for continued smoking, followed by pleasure and addiction. Although the score for nicotine dependence was low, addiction was an important reason for continued smoking during pregnancy; therefore, nicotine replacement therapy could be considered. Half of the respondents experienced depressive symptoms. Hence, it is important to identify those women who need more specialized care, which can include not only smoking cessation counselling but also treatment for depression. © 2016 John Wiley & Sons, Ltd.
Directory of Open Access Journals (Sweden)
Eduardo de Paula Lima
2012-01-01
Full Text Available INTRODUCTION: Posttraumatic stress disorder (PTSD is an anxiety disorder resulting from exposure to traumatic events. The Posttraumatic Stress Disorder Checklist (PCL is a self-report measure largely used to evaluate the presence of PTSD. OBJECTIVE: To investigate the internal consistency, temporal reliability and factor validity of the Portuguese language version of the PCL used in Brazil. METHODS: A total of 186 participants were recruited. The sample was heterogeneous with regard to occupation, sociodemographic data, mental health history, and exposure to traumatic events. Subjects answered the PCL at two occasions within a 15 days’ interval (range: 5-15 days. RESULTS: Cronbach’s alpha coefficients indicated high internal consistency for the total scale (0.91 and for the theoretical dimensions of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV (0.83, 0.81, and 0.80. Temporal reliability (test-retest was high and consistent for different cutoffs. Maximum likelihood exploratory factor analysis (EFA was conducted and oblique rotation (Promax was applied. The Kaiser-Meyer-Olkin (KMO index (0.911 and Bartlett’s test of sphericity (χ² = 1,381.34, p INTRODUÇÃO: O transtorno do estresse pós-traumático (TEPT é um transtorno de ansiedade decorrente da exposição a eventos traumáticos. Entre as medidas de avaliação dos sintomas, destaca-se o Posttraumatic Stress Disorder Checklist (PCL. OBJETIVO: Investigar a consistência interna, a confiabilidade temporal e a validade fatorial da versão do PCL em português, utilizada no Brasil. MÉTODOS: Participaram do estudo 186 indivíduos heterogêneos em relação a ocupação, características sociodemográficas, histórico de saúde mental e exposição a eventos traumáticos. O PCL foi aplicado em dois momentos considerando um intervalo máximo de 15 dias (intervalo: 5-15 dias. RESULTADOS: A consistência interna (alfa de Cronbach foi adequada para a escala
Structural Reliability Using Probability Density Estimation Methods Within NESSUS
Chamis, Chrisos C. (Technical Monitor); Godines, Cody Ric
2003-01-01
A reliability analysis studies a mathematical model of a physical system taking into account uncertainties of design variables and common results are estimations of a response density, which also implies estimations of its parameters. Some common density parameters include the mean value, the standard deviation, and specific percentile(s) of the response, which are measures of central tendency, variation, and probability regions, respectively. Reliability analyses are important since the results can lead to different designs by calculating the probability of observing safe responses in each of the proposed designs. All of this is done at the expense of added computational time as compared to a single deterministic analysis which will result in one value of the response out of many that make up the density of the response. Sampling methods, such as monte carlo (MC) and latin hypercube sampling (LHS), can be used to perform reliability analyses and can compute nonlinear response density parameters even if the response is dependent on many random variables. Hence, both methods are very robust; however, they are computationally expensive to use in the estimation of the response density parameters. Both methods are 2 of 13 stochastic methods that are contained within the Numerical Evaluation of Stochastic Structures Under Stress (NESSUS) program. NESSUS is a probabilistic finite element analysis (FEA) program that was developed through funding from NASA Glenn Research Center (GRC). It has the additional capability of being linked to other analysis programs; therefore, probabilistic fluid dynamics, fracture mechanics, and heat transfer are only a few of what is possible with this software. The LHS method is the newest addition to the stochastic methods within NESSUS. Part of this work was to enhance NESSUS with the LHS method. The new LHS module is complete, has been successfully integrated with NESSUS, and been used to study four different test cases that have been
Reliable LED Lighting Technologies: Key Factors and Procurement Guidance
Energy Technology Data Exchange (ETDEWEB)
Davis, Lynn; Arquit Niederberger, Anne
2015-10-08
Abstract— Lighting systems have the ability to transform the economic and educational infrastructure of disadvantaged communities, and eradicating “light poverty” has become one of the primary goals of the International Year of Light 2015. Solid-state lighting (SSL) technology, based on light-emitting diode (LED) light sources, has emerged as the next generation of lighting technology, with a current global market penetration of roughly 5%. This paper will report on recent research on understanding SSL lighting system reliability (failure modes, environmental stressors, electrical power quality); discuss the implications of SSL technology reliability for providing lighting services; and suggest practical approaches to ensure SSL reliability to benefit humanity. Among the key findings from this work is that LED sources can be extremely reliable, withstanding a broad range of environmental stresses without failure. Nonetheless, SSL lighting systems can have a negative impact on electrical power reliability, as well as on the affordability of lighting services, without attention to the quality of the accompanying power infrastructure. It is therefore critical to ensure that the performance of the power supply electronics used in lighting systems is matched to the quality of the power source, when evaluating energy efficient lighting choices.
Sil, Arjun; Longmailai, Thaihamdau
2017-09-01
The lateral displacement of Reinforced Concrete (RC) frame building during an earthquake has an important impact on the structural stability and integrity. However, seismic analysis and design of RC building needs more concern due to its complex behavior as the performance of the structure links to the features of the system having many influencing parameters and other inherent uncertainties. The reliability approach takes into account the factors and uncertainty in design influencing the performance or response of the structure in which the safety level or the probability of failure could be ascertained. This present study, aims to assess the reliability of seismic performance of a four storey residential RC building seismically located in Zone-V as per the code provisions given in the Indian Standards IS: 1893-2002. The reliability assessment performed by deriving an explicit expression for maximum roof-lateral displacement as a failure function by regression method. A total of 319, four storey RC buildings were analyzed by linear static method using SAP2000. However, the change in the lateral-roof displacement with the variation of the parameters (column dimension, beam dimension, grade of concrete, floor height and total weight of the structure) was observed. A generalized relation established by regression method which could be used to estimate the expected lateral displacement owing to those selected parameters. A comparison made between the displacements obtained from analysis with that of the equation so formed. However, it shows that the proposed relation could be used directly to determine the expected maximum lateral displacement. The data obtained from the statistical computations was then used to obtain the probability of failure and the reliability.
The effect of corrosion on the structural reliability of steel offshore structures
International Nuclear Information System (INIS)
Melchers, Robert E.
2005-01-01
This paper considers essential theoretical concepts and data requirements for engineering structural reliability assessment suitable for the estimation of the safety and reliability of corroding ships, offshore structures and pipelines. Such infrastructure operates in a harsh environment. Allowance must be made for structural deterioration since protective measures such as paint coatings, galvanizing or cathodic protection may be ineffective. Reliability analysis requires accurate engineering models for the description and prediction of material corrosion loss and for the maximum depth of pitting. New probability-based models for both these forms of corrosion have been proposed recently and calibrated against a wide range of data. The effects of water velocity and of water pollution are reviewed and compared with recently reported field data for a corrosion at an offshore oil platform. The data interpreted according to the model show good correlation when allowance is made for the season of first immersion and the adverse effects of seawater velocity and of water pollution. An example is given to illustrate the application of reliability analysis to a pipeline subject to pitting corrosion. An important outcome is that good quality estimation of the longer-term probability of loss of structural integrity requires good modelling of the longer-term corrosion behaviour. This is usually associated with anaerobic corrosion. As a result, it cannot be extrapolated from data for short-term corrosion as this is associated with aerobic corrosion conditions
The effect of corrosion on the structural reliability of steel offshore structures
Energy Technology Data Exchange (ETDEWEB)
Melchers, Robert E. [Centre for Infrastructure Performance and Reliability, Department of Civil, Surveying and Environmental Engineering, School of Engineering, University of Newcastle, University Drive, Callaghan NSW 2300 (Australia)]. E-mail: rob.melchers@newcastle.edu.au
2005-10-01
This paper considers essential theoretical concepts and data requirements for engineering structural reliability assessment suitable for the estimation of the safety and reliability of corroding ships, offshore structures and pipelines. Such infrastructure operates in a harsh environment. Allowance must be made for structural deterioration since protective measures such as paint coatings, galvanizing or cathodic protection may be ineffective. Reliability analysis requires accurate engineering models for the description and prediction of material corrosion loss and for the maximum depth of pitting. New probability-based models for both these forms of corrosion have been proposed recently and calibrated against a wide range of data. The effects of water velocity and of water pollution are reviewed and compared with recently reported field data for a corrosion at an offshore oil platform. The data interpreted according to the model show good correlation when allowance is made for the season of first immersion and the adverse effects of seawater velocity and of water pollution. An example is given to illustrate the application of reliability analysis to a pipeline subject to pitting corrosion. An important outcome is that good quality estimation of the longer-term probability of loss of structural integrity requires good modelling of the longer-term corrosion behaviour. This is usually associated with anaerobic corrosion. As a result, it cannot be extrapolated from data for short-term corrosion as this is associated with aerobic corrosion conditions.
Fatigue Reliability and Calibration of Fatigue Design Factors for Offshore Wind Turbines
Directory of Open Access Journals (Sweden)
Sergio Márquez-Domínguez
2012-06-01
Full Text Available Consequences of failure of offshore wind turbines (OWTs is in general lower than consequences of failure of, e.g., oil & gas platforms. It is reasonable that lower fatigue design factors can be applied for fatigue design of OWTs when compared to other fixed offshore structures. Calibration of appropriate partial safety factors/Fatigue Design Factors (FDF for steel substructures for OWTs is the scope of this paper. A reliability-based approach is used and a probabilistic model has been developed, where design and limit state equations are established for fatigue failure. The strength and load uncertainties are described by stochastic variables. SN and fracture mechanics approaches are considered for to model the fatigue life. Further, both linear and bi-linear SN-curves are formulated and various approximations are investigated. The acceptable reliability level for fatigue failure of OWTs is discussed and results are presented for calibrated optimal fatigue design factors. Further, the influence of inspections is considered in order to extend and maintain a given target safety level.
Noteborn, M.G.C.; Hildebrand, M.
2015-01-01
Background: The use of brief, reliable, valid, and practical measures of substance use is critical for conducting individual (risk and need) assessments in probation practice. In this exploratory study, the basic psychometric properties of the Alcohol Use Disorders Identification Test (AUDIT) and
Factorization of Constrained Energy K-Network Reliability with Perfect Nodes
Burgos, Juan Manuel
2013-01-01
This paper proves a new general K-network constrained energy reliability global factorization theorem. As in the unconstrained case, beside its theoretical mathematical importance the theorem shows how to do parallel processing in exact network constrained energy reliability calculations in order to reduce the processing time of this NP-hard problem. Followed by a new simple factorization formula for its calculation, we propose a new definition of constrained energy network reliability motiva...
CARES/PC - CERAMICS ANALYSIS AND RELIABILITY EVALUATION OF STRUCTURES
Szatmary, S. A.
1994-01-01
The beneficial properties of structural ceramics include their high-temperature strength, light weight, hardness, and corrosion and oxidation resistance. For advanced heat engines, ceramics have demonstrated functional abilities at temperatures well beyond the operational limits of metals. This is offset by the fact that ceramic materials tend to be brittle. When a load is applied, their lack of significant plastic deformation causes the material to crack at microscopic flaws, destroying the component. CARES/PC performs statistical analysis of data obtained from the fracture of simple, uniaxial tensile or flexural specimens and estimates the Weibull and Batdorf material parameters from this data. CARES/PC is a subset of the program CARES (COSMIC program number LEW-15168) which calculates the fast-fracture reliability or failure probability of ceramic components utilizing the Batdorf and Weibull models to describe the effects of multi-axial stress states on material strength. CARES additionally requires that the ceramic structure be modeled by a finite element program such as MSC/NASTRAN or ANSYS. The more limited CARES/PC does not perform fast-fracture reliability estimation of components. CARES/PC estimates ceramic material properties from uniaxial tensile or from three- and four-point bend bar data. In general, the parameters are obtained from the fracture stresses of many specimens (30 or more are recommended) whose geometry and loading configurations are held constant. Parameter estimation can be performed for single or multiple failure modes by using the least-squares analysis or the maximum likelihood method. Kolmogorov-Smirnov and Anderson-Darling goodness-of-fit tests measure the accuracy of the hypothesis that the fracture data comes from a population with a distribution specified by the estimated Weibull parameters. Ninety-percent confidence intervals on the Weibull parameters and the unbiased value of the shape parameter for complete samples are provided
Optimization and Reliability Problems in Structural Design of Wind Turbines
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
2007-01-01
are discussed. Limit state equations are presented for fatigue limit states and for ultimate limit states with extreme wind load, and illustrated by bending failure. Illustrative examples are presented, and as a part of the results optimal reliability levels are obtained which corresponds to an annual...... reliability index equal to 3. An example with fatigue failure indicates that the reliability level is almost the same for single wind turbines and for wind turbines in wind farms if the wake effects are modeled equivalently in the design equation and the limit state equation....
Directory of Open Access Journals (Sweden)
Vuković Mira H.
2015-01-01
Full Text Available Introduction: The structure of healthcare professionals' economic reasoning (HPER is still unknown. The aim: The structural validity and the reliability of the HPER questionnaire were evaluated. Methods: The psychometric study about evaluation of the HPER factors was conducted. The healthcare professionals (physicians, dentists, pharmacists that are employed in healthcare state sector of Republic of Serbia were interviewed. The HPER Questionnaire contained 29 preliminary items. Its structure was evaluated by Principal Component Analysis for categorial and ordinal data. Results: The 9 items that defined seven HPER factors were extracted: (1 the negligence of the cost of quality by the administration and financier; (2 the consideration of the market price and healthcare benefit; (3 market orientation considering patient's requests; (4 the recognition of inadequate resource alocations by non-medical administrative authority; (5 the attitude about redirecting the profit from state to private healthcare sector; (6 the recognition of the unjustified spending by the healthcare professionals and (7 the relationship physician/patient. Conclusion: The HPER-9 Questionnaire has high structural validity and reliability in the HPER measurement.
Effects of structural modification on reliability of nanoscale nitride HEMTs
Gaddipati, Vamsi Mohan
AlGaN based nanoscale high-electron-mobility transistors (HEMTs) are the next generation of transistor technology that features the unique combination of higher power, wider bandwidth, low noise, higher efficiency, and temperature/radiation hardness than conventional AlGaAs and Si based technologies. However, as evidenced by recent stress tests, reliability of these devices (characterized by a gradual decrease in the output current/power leading to failure of the device in just tens of hours of operation) remains a major concern. Although, in these tests, physical damages were clearly visible in the device, the root cause and nature of these damages have not yet been fully assessed experimentally. Therefore, a comprehensive theoretical study of the physical mechanisms responsible for degradation of AlGaN HEMTs is essential before these devices are deployed in targeted applications. The main objective of the proposed research is to computationally investigate how degradation of state-of-the-art nanoscale AlGaN HEMTs is governed by an intricate and dynamical coupling of thermo-electromechanical processes at different length (atoms-to-transistor) and time (femtosecondto- hours) scales while operating in high voltage, large mechanical, and high temperature/radiation stresses. This work centers around a novel hypotheses as follows: High voltage applied to AlGaN HEMT causes excessive internal heat dissipation, which triggers gate metal diffusion into the semiconducting barrier layer and structural modifications (defect ii formation) leading to diminished polarization induced charge density and output current. Since the dynamical system to be studied is complex, chaotic (where the evolution rule is guided by atomicity of the underlying material), and involve coupled physical processes, an in-house multiscale simulator (QuADS 3-D) has been employed and augmented, where material parameters are obtained atomistically using firstprinciples, structural relaxation and defect
International Nuclear Information System (INIS)
Jiang Jianjun; Zhang Li; Wang Yiqun; Zhang Kun; Peng Yuyuan; Zhou Cheng
2012-01-01
Facing the shortcomings of the traditional cognitive factors and cognitive model, this paper presents a Bayesian networks cognitive reliability model by taking the main control room as a reference background and human factors as the key points. The model mainly analyzes the cognitive reliability affected by the human factors, and for the cognitive node and influence factors corresponding to cognitive node, a series of methods and function formulas to compute the node cognitive reliability is proposed. The model and corresponding methods can be applied to the evaluation of cognitive process for the nuclear power plant operators and have a certain significance for the prevention of safety accidents in nuclear power plants. (authors)
[The impact factor--a reliable sciento-metric parameter?].
Meenen, N M
1997-08-01
With shortage of research funds and increasing competition for medical posts, performance indicators and control instruments are being looked for in order to be able to allot research funds and make professorial appointments in relation to scientific performance. Incomprehensibly for many, the impact factor has become the decisive scientometric indicator at German universities despite of substantial systematic limitations. The impact factor is derived from the journal citation reports. Its basis of calculation entails the following problems: the editorial board of the private Institute of Scientific Information (ISI) decides on whether a journal is to be classified as a source journal. The citation index of all journals is calculated from their citations alone. Crucial means of influencing the impact factor result from self-citations and citation groups in these source journals. Languages other than English and other than Latin alphabets are appreciably disadvantaged by the citation index, which is why for example despite its international significance the rapid development of the osteosynthesis technique in German speaking countries went unnoticed by British and American orthopedic surgeons and scientists. The articles on postgraduate training necessarily published by clinicians in the respective language of their country are not cited because the addresses of such publications do not engage in research. Clinical disciplines (especially highly specialized disciplines such as trauma and hand surgery) thus attain appreciably lower impact factors for their journals than basic disciplines and interdisciplinary clinical sectors which lead the ranking of journals. The period covered in calculating the impact factor is only 2 years. Very modern and widely disseminated organs of publication with a short information halflife are favored. From the 10 objectively most often cited and most important journals for the scientific society, only 2 are to be found amongst those
Extented second moment algebra as an efficient tool in structural reliability
International Nuclear Information System (INIS)
Ditlevsen, O.
1982-01-01
During the seventies, second moment structural reliability analysis was extensively discussed with respect to philosophy and method. One recent clarification into a consistent formalism is represented by the extended second moment reliability theory with the generalized reliability index as its measure of safety. Its methods of formal failure probability calculations are useful independent of the opinion that one may adopt about the philosophy of the second moment reliability formalism. After an introduction of the historical development of the philosphy the paper gives a short introductory review of the extended second moment structural reliability theory. (orig.)
Analysis of time-dependent reliability of degenerated reinforced concrete structure
Directory of Open Access Journals (Sweden)
Zhang Hongping
2016-07-01
Full Text Available Durability deterioration of structure is a highly random process. The maintenance of degenerated structure involves the calculation of the reliability of time-dependent structure. This study introduced reinforced concrete structure resistance decrease model and related statistical parameters of uncertainty, analyzed resistance decrease rules of corroded bending element of reinforced concrete structure, and finally calculated timedependent reliability of the corroded bending element of reinforced concrete structure, aiming to provide a specific theoretical basis for the application of time-dependent reliability theory.
Total Longitudinal Moment Calculation and Reliability Analysis of Yacht Structures
Zhi, Wenzheng; Lin, Shaofen
In order to check the reliability of the yacht in FRP (Fiber Reinforce Plastic) materials, in this paper, the vertical force and the calculation method of the overall longitudinal bending moment on yacht was analyzed. Specially, this paper focuses on the impact of speed on the still water bending moment on yacht. Then considering the mechanical properties of the cap type stiffeners in composite materials, the ultimate bearing capacity of the yacht has been worked out, finally the reliability of the yacht was calculated with using response surface methodology. The result can be used in yacht design and yacht driving.
Level III Reliability methods feasible for complex structures
Waarts, P.H.; Boer, A. de
2001-01-01
The paper describes the comparison between three types of reliability methods: code type level I used by a designer, full level I and a level III method. Two cases that are typical for civil engineering practise, a cable-stayed subjected to traffic load and the installation of a soil retaining sheet
Reliability of redundant ductile structures with uncertain system ...
Indian Academy of Sciences (India)
tance, applied loads and geometric parameters, and in some cases in the .... Statistical dependence among (i) girder strengths ... element reliability solution techniques; such formulation unfortunately remains ..... The spread of plasticity through a member after failure of a section .... The following form of the bivariate Gumbel.
The structure factor of primes
Zhang, G.; Martelli, F.; Torquato, S.
2018-03-01
Although the prime numbers are deterministic, they can be viewed, by some measures, as pseudo-random numbers. In this article, we numerically study the pair statistics of the primes using statistical-mechanical methods, particularly the structure factor S(k) in an interval M ≤slant p ≤slant M + L with M large, and L/M smaller than unity. We show that the structure factor of the prime-number configurations in such intervals exhibits well-defined Bragg-like peaks along with a small ‘diffuse’ contribution. This indicates that primes are appreciably more correlated and ordered than previously thought. Our numerical results definitively suggest an explicit formula for the locations and heights of the peaks. This formula predicts infinitely many peaks in any non-zero interval, similar to the behavior of quasicrystals. However, primes differ from quasicrystals in that the ratio between the location of any two predicted peaks is rational. We also show numerically that the diffuse part decays slowly as M and L increases. This suggests that the diffuse part vanishes in an appropriate infinite-system-size limit.
Factors that may compromise bulk water distribution reliability
2012-01-01
D.Ing. This thesis considers water supply and divides the water supply environment into three categories; the macro water supply environment, the water supply scheme and the consumers. Each of the categories is briefly explored in terms of the factors that may influence it. Subsequently, some of the unique features of a bulk water distribution system are dealt with, as well as different approaches related to bulk water distribution system design and assessment. One of these approaches, the...
Directory of Open Access Journals (Sweden)
Abdelbaki Laidoune
2016-09-01
Conclusion: The explored sociocultural factors influence the human reliability both in qualitative and quantitative manners. The proposed model shows how reliability can be enhanced by some measures such as experience feedback based on, for example, safety improvements, training, and information. With that is added the continuous systems improvements to improve sociocultural reality and to reduce negative behaviors.
Yu, Taeho; Richardson, Jennifer C.
2015-01-01
The purpose of this study was to develop an effective instrument to measure student readiness in online learning with reliable predictors of online learning success factors such as learning outcomes and learner satisfaction. The validity and reliability of the Student Online Learning Readiness (SOLR) instrument were tested using exploratory factor…
International Nuclear Information System (INIS)
Stewart, Mark G.; Al-Harthy, Ali
2008-01-01
A stochastic analysis is developed to assess the temporal and spatial variability of pitting corrosion on the reliability of corroding reinforced concrete (RC) structures. The structure considered herein is a singly reinforced RC beam with Y16 or Y27 reinforcing bars. Experimental data obtained from corrosion tests are used to characterise the probability distribution of pit depth. The RC beam is discretised into a series of small elements and maximum pit depths are generated for each reinforcing steel bar in each element. The loss of cross-sectional area, reduction in yield strength and reduction in flexural resistance are then inferred. The analysis considers various member spans, loading ratios, bar diameters and numbers of bars in a given cross-section, and moment diagrams. It was found that the maximum corrosion loss in a reinforcing bar conditional on beam collapse was no more than 16%. The probabilities of failure considering spatial variability of pitting corrosion were up to 200% higher than probabilities of failure obtained from a non-spatial analysis after 50 years of corrosion. This shows the importance of considering spatial variability in a structural reliability analysis for deteriorating structures, particularly for corroding RC beams in flexure
DEFF Research Database (Denmark)
Iwankiewicz, R.; Nielsen, Søren R. K.; Skjærbæk, P. S.
The subject of the paper is the investigation of the sensitivity of structural reliability estimation by a reduced hysteretic model for a reinforced concrete frame under an earthquake excitation.......The subject of the paper is the investigation of the sensitivity of structural reliability estimation by a reduced hysteretic model for a reinforced concrete frame under an earthquake excitation....
Reliability and service life of wood structures and buildings
Directory of Open Access Journals (Sweden)
Zdeňka Havířová
2005-01-01
Full Text Available Service life of constructions and buildings of wood is dependent on temperature and moisture conditions in layers of the building cladding where the wood framework is built in. Temperature/moisture conditions or the corresponding equilibrium moisture content (EMC of the construction show considerable effects on the functional reliability of the whole building from the viewpoint of mechanical resistance and stability (ER1, energy savings and thermal protection (ER6 and hygiene, health and environment protection (ER3. To ensure the reliability of constructions and buildings for the period of their supposed service life a more profound analysis of constructions is necessary from the aspect of a global thermal/technical evaluation.
Reliability and service life of wood structures and buildings
Zdeňka Havířová; Pavel Kubů
2005-01-01
Service life of constructions and buildings of wood is dependent on temperature and moisture conditions in layers of the building cladding where the wood framework is built in. Temperature/moisture conditions or the corresponding equilibrium moisture content (EMC) of the construction show considerable effects on the functional reliability of the whole building from the viewpoint of mechanical resistance and stability (ER1), energy savings and thermal protection (ER6) and hygiene, health and e...
Reliability estimation of structures under stochastic loading—A case study on nuclear piping
International Nuclear Information System (INIS)
Hari Prasad, M.; Rami Reddy, G.; Dubey, P.N.; Srividya, A.; Verma, A.K.
2013-01-01
Highlights: ► Structures are generally subjected to different types of loadings. ► One such type of loading is random sequence and has been treated as a stochastic fatigue loading. ► In this methodology both stress amplitude and number of cycles to failure have been considered as random variables. ► The methodology has been demonstrated with a case study on nuclear piping. ► The failure probability of piping has been estimated as a function of time. - Abstract: Generally structures are subjected to different types of loadings throughout their life time. These loads can be either discrete in nature or continuous in nature and also these can be either stationary or non stationary processes. This means that the structural reliability analysis not only considers random variables but also considers random variables which are functions of time, referred to as stochastic processes. A stochastic process can be viewed as a family of random variables. When a structure is subjected to a random loading, based on the stresses developed in the structure and failure criteria the failure probability can be estimated. In practice the structures are designed with higher factor of safety to take care of such random loads. In such cases the structure will fail only when the random loads are cyclic in nature. In traditional reliability analysis, the variation in the load is treated as a random variable and to account for the number of occurrences of the loading the concept of extreme value theory is used. But with this method one is neglecting the damage accumulation that will take place from one loading to another loading. Hence, in this paper, a new way of dealing with these types of problems has been discussed by using the concept of stochastic fatigue loading. The random loading has been considered as earthquake loading. The methodology has been demonstrated with a case study on nuclear power plant piping.
An Energy-Based Limit State Function for Estimation of Structural Reliability in Shock Environments
Directory of Open Access Journals (Sweden)
Michael A. Guthrie
2013-01-01
Full Text Available limit state function is developed for the estimation of structural reliability in shock environments. This limit state function uses peak modal strain energies to characterize environmental severity and modal strain energies at failure to characterize the structural capacity. The Hasofer-Lind reliability index is briefly reviewed and its computation for the energy-based limit state function is discussed. Applications to two degree of freedom mass-spring systems and to a simple finite element model are considered. For these examples, computation of the reliability index requires little effort beyond a modal analysis, but still accounts for relevant uncertainties in both the structure and environment. For both examples, the reliability index is observed to agree well with the results of Monte Carlo analysis. In situations where fast, qualitative comparison of several candidate designs is required, the reliability index based on the proposed limit state function provides an attractive metric which can be used to compare and control reliability.
Determination of the Level of Influence of Various Factors on the Reliability of Power System
Directory of Open Access Journals (Sweden)
Victor Popescu
2014-09-01
Full Text Available Consumers supply with qualitative electric power is one of the priority requirements imposed to power systems. Currently, in electricity networks take place a number of planned and unplanned disconnections, which interrupt the power and affect consumers, causing economic damage. To ensure the quality of power supply it is essential to know the factors that influence the reliability of power systems, which have a visible impact on the variation of reliability of equipment installed in power systems. This paper is devoted to problems of calculation and analysis of power systems reliability and estimation of the impact of various factors that influence the supply of consumers.
Factors Influencing the Reliability of the Glasgow Coma Scale: A Systematic Review.
Reith, Florence Cm; Synnot, Anneliese; van den Brande, Ruben; Gruen, Russell L; Maas, Andrew Ir
2017-06-01
The Glasgow Coma Scale (GCS) characterizes patients with diminished consciousness. In a recent systematic review, we found overall adequate reliability across different clinical settings, but reliability estimates varied considerably between studies, and methodological quality of studies was overall poor. Identifying and understanding factors that can affect its reliability is important, in order to promote high standards for clinical use of the GCS. The aim of this systematic review was to identify factors that influence reliability and to provide an evidence base for promoting consistent and reliable application of the GCS. A comprehensive literature search was undertaken in MEDLINE, EMBASE, and CINAHL from 1974 to July 2016. Studies assessing the reliability of the GCS in adults or describing any factor that influences reliability were included. Two reviewers independently screened citations, selected full texts, and undertook data extraction and critical appraisal. Methodological quality of studies was evaluated with the consensus-based standards for the selection of health measurement instruments checklist. Data were synthesized narratively and presented in tables. Forty-one studies were included for analysis. Factors identified that may influence reliability are education and training, the level of consciousness, and type of stimuli used. Conflicting results were found for experience of the observer, the pathology causing the reduced consciousness, and intubation/sedation. No clear influence was found for the professional background of observers. Reliability of the GCS is influenced by multiple factors and as such is context dependent. This review points to the potential for improvement from training and education and standardization of assessment methods, for which recommendations are presented. Copyright © 2017 by the Congress of Neurological Surgeons.
On the use of NDT Data for Reliability-Based Assessment of Existing Timber Structures
DEFF Research Database (Denmark)
Sousa, Hélder S.; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning
2013-01-01
The objective of this paper is to address the possibilities of using non-destructive testing (NDT) data for updating information and obtaining adequate characterization of the reliability level of existing timber structures and, also, for assessing the evolution in time of performance...... of these structures when exposed to deterioration. By improving the knowledge upon the mechanical properties of timber, better and more substantiated decisions after a reliability safety assessment are aimed at. Bayesian methods are used to update the mechanical properties of timber and reliability assessment......, and information of NDT is also used to calibrate these models. The proposed approach is used for reliability assessment of different structural timber systems. Reliability of the structural system is assessed regarding the failure consequences of individual elements defined as key elements which were determined...
Reliability Analysis of Sealing Structure of Electromechanical System Based on Kriging Model
Zhang, F.; Wang, Y. M.; Chen, R. W.; Deng, W. W.; Gao, Y.
2018-05-01
The sealing performance of aircraft electromechanical system has a great influence on flight safety, and the reliability of its typical seal structure is analyzed by researcher. In this paper, we regard reciprocating seal structure as a research object to study structural reliability. Having been based on the finite element numerical simulation method, the contact stress between the rubber sealing ring and the cylinder wall is calculated, and the relationship between the contact stress and the pressure of the hydraulic medium is built, and the friction force on different working conditions are compared. Through the co-simulation, the adaptive Kriging model obtained by EFF learning mechanism is used to describe the failure probability of the seal ring, so as to evaluate the reliability of the sealing structure. This article proposes a new idea of numerical evaluation for the reliability analysis of sealing structure, and also provides a theoretical basis for the optimal design of sealing structure.
Application of reliability based design concepts to transmission line structure foundations. Part 2
International Nuclear Information System (INIS)
DiGioia, A.M. Jr.; Rojas-Gonzalez, L.F.
1991-01-01
The application of reliability based design (RBD) methods to transmission line structure foundations has developed somewhat more slowly than that for the other structural components in line systems. In a previous paper, a procedure was proposed for the design of transmission line structures foundations using a probability based load and resistance factor design (LRFD) format. This procedure involved the determination of a foundation strength factor, φ F , which was used as a multiplier of the calculated nominal design strength to estimate the five percent exclusion limit strength required in the calculated nominal design strength to estimate the five percent exclusion limit strength required in the LRFD equation. Statistical analyses of results from full-scale load tests were used to obtain φ F values applicable to various nominal design strength equations and for drilled shafts subjected to uplift loads. These results clearly illustrated the significant economic benefits of conducting more detailed subsurface investigations for the design of transmission line structure foundations. A design example was also presented. In this paper the proposed procedure is extended to laterally load drilled shafts
International Nuclear Information System (INIS)
Khatibinia, Mohsen; Javad Fadaee, Mohammad; Salajegheh, Javad; Salajegheh, Eysa
2013-01-01
An efficient metamodeling framework in conjunction with the Monte-Carlo Simulation (MCS) is introduced to reduce the computational cost in seismic reliability assessment of existing RC structures. In order to achieve this purpose, the metamodel is designed by combining weighted least squares support vector machine (WLS-SVM) and a wavelet kernel function, called wavelet weighted least squares support vector machine (WWLS-SVM). In this study, the seismic reliability assessment of existing RC structures with consideration of soil–structure interaction (SSI) effects is investigated in accordance with Performance-Based Design (PBD). This study aims to incorporate the acceptable performance levels of PBD into reliability theory for comparing the obtained annual probability of non-performance with the target values for each performance level. The MCS method as the most reliable method is utilized to estimate the annual probability of failure associated with a given performance level in this study. In WWLS-SVM-based MCS, the structural seismic responses are accurately predicted by WWLS-SVM for reducing the computational cost. To show the efficiency and robustness of the proposed metamodel, two RC structures are studied. Numerical results demonstrate the efficiency and computational advantages of the proposed metamodel for the seismic reliability assessment of structures. Furthermore, the consideration of the SSI effects in the seismic reliability assessment of existing RC structures is compared to the fixed base model. It shows which SSI has the significant influence on the seismic reliability assessment of structures.
System reliability of concrete structures subjected to chloride ingress
DEFF Research Database (Denmark)
Leira, B.J.; Thöns, Sebastian
2017-01-01
attack on the entire bridge, a system model with 90 components is next introduced. This model is employed in order to perform reliability updating based on observations at a number of sites along the bridge. An Enhanced Monte Carlo simulation method (EMC) is applied for this purpose. It is shown...... that application of this simulation method reduces computation times significantly as compared to crude Monte Carlo methods....... are obtained based on measurements from the Gimsøystraumen bridge in Norway. These probability distributions are subsequently employed as input to a prediction model for chloride concentration at the steel reinforcement for a single but arbitrary position along the reinforcement. In order to address chloride...
A study in the reliability analysis method for nuclear power plant structures (I)
Energy Technology Data Exchange (ETDEWEB)
Oh, Byung Hwan; Choi, Seong Cheol; Shin, Ho Sang; Yang, In Hwan; Kim, Yi Sung; Yu, Young; Kim, Se Hun [Seoul, Nationl Univ., Seoul (Korea, Republic of)
1999-03-15
Nuclear power plant structures may be exposed to aggressive environmental effects that may cause their strength and stiffness to decrease over their service life. Although the physics of these damage mechanisms are reasonably well understood and quantitative evaluation of their effects on time-dependent structural behavior is possible in some instances, such evaluations are generally very difficult and remain novel. The assessment of existing steel containment in nuclear power plants for continued service must provide quantitative evidence that they are able to withstand future extreme loads during a service period with an acceptable level of reliability. Rational methodologies to perform the reliability assessment can be developed from mechanistic models of structural deterioration, using time-dependent structural reliability analysis to take loading and strength uncertainties into account. The final goal of this study is to develop the analysis method for the reliability of containment structures. The cause and mechanism of corrosion is first clarified and the reliability assessment method has been established. By introducing the equivalent normal distribution, the procedure of reliability analysis which can determine the failure probabilities has been established. The influence of design variables to reliability and the relation between the reliability and service life will be continued second year research.
Quantifiable and Reliable Structural Health Management Systems, Phase II
National Aeronautics and Space Administration — Under Project Constellation, NASA is developing a new generation of spacecraft for human spaceflight. A significant percentage of the structures used in these...
Reliability Evaluation and Probabilistic Design of Coastal Structures
DEFF Research Database (Denmark)
Burcharth, H. F.
1993-01-01
Conventional design practice for coastal structures is deterministic in nature and is based on the concept of a design load, which should not exceed the resistance (carrying capacity) of the structure. The design load is usually defined on a probabilistic basis as a characteristic value of the load......, e.g. the expectation (mean) value of the lOO-year return period event, however, often without consideration of the involved uncertainties. The resistance is in most cases defined in terms of the load which causes a certain design impact or damage to the structure and is not given as an ultimate...... force or deformation. This is because most of the available design formulae only give the relationship between wave characteristics and structural response, e.g. in terms of run-up, overtopping, armour layer damage etc. An example is the Hudson formula for armour layer stability. Almost all such design...
structural reliability of the nigerian grown abura timber bridge beam
African Journals Online (AJOL)
ENGR. J. I. AGUWA
2013-07-02
Jul 2, 2013 ... Structural analysis and deterministic design of a timber bridge beam using the Nigerian ... practice especially when it involves naturally occuring materials .... the beam due to distributed loads is; from [15]. (4). It is assumed that ...
Sensitivity based reduced approaches for structural reliability analysis
Indian Academy of Sciences (India)
captured by a safety-factor based approach due to the intricate nonlinear ... give the accounts of extensive research works which have been done over ... (ii) simulation based methods, for example, importance sampling (Bucher 1988; Mahade-.
Blouin, Danielle; Day, Andrew G; Pavlov, Andrey
2011-12-01
Although never directly compared, structured interviews are reported as being more reliable than unstructured interviews. This study compared the reliability of both types of interview when applied to a common pool of applicants for positions in an emergency medicine residency program. In 2008, one structured interview was added to the two unstructured interviews traditionally used in our resident selection process. A formal job analysis using the critical incident technique guided the development of the structured interview tool. This tool consisted of 7 scenarios assessing 4 of the domains deemed essential for success as a resident in this program. The traditional interview tool assessed 5 general criteria. In addition to these criteria, the unstructured panel members were asked to rate each candidate on the same 4 essential domains rated by the structured panel members. All 3 panels interviewed all candidates. Main outcomes were the overall, interitem, and interrater reliabilities, the correlations between interview panels, and the dimensionality of each interview tool. Thirty candidates were interviewed. The overall reliability reached 0.43 for the structured interview, and 0.81 and 0.71 for the unstructured interviews. Analyses of the variance components showed a high interrater, low interitem reliability for the structured interview, and a high interrater, high interitem reliability for the unstructured interviews. The summary measures from the 2 unstructured interviews were significantly correlated, but neither was correlated with the structured interview. Only the structured interview was multidimensional. A structured interview did not yield a higher overall reliability than both unstructured interviews. The lower reliability is explained by a lower interitem reliability, which in turn is due to the multidimensionality of the interview tool. Both unstructured panels consistently rated a single dimension, even when prompted to assess the 4 specific domains
Further HTGR core support structure reliability studies. Interim report No. 1
International Nuclear Information System (INIS)
Platus, D.L.
1976-01-01
Results of a continuing effort to investigate high temperature gas cooled reactor (HTGR) core support structure reliability are described. Graphite material and core support structure component physical, mechanical and strength properties required for the reliability analysis are identified. Also described are experimental and associated analytical techniques for determining the required properties, a procedure for determining number of tests required, properties that might be monitored by special surveillance of the core support structure to improve reliability predictions, and recommendations for further studies. Emphasis in the study is directed towards developing a basic understanding of graphite failure and strength degradation mechanisms; and validating analytical methods for predicting strength and strength degradation from basic material properties
Assessment of modern methods of human factor reliability analysis in PSA studies
International Nuclear Information System (INIS)
Holy, J.
2001-12-01
The report is structured as follows: Classical terms and objects (Probabilistic safety assessment as a framework for human reliability assessment; Human failure within the PSA model; Basic types of operator failure modelled in a PSA study and analyzed by HRA methods; Qualitative analysis of human reliability; Quantitative analysis of human reliability used; Process of analysis of nuclear reactor operator reliability in a PSA study); New terms and objects (Analysis of dependences; Errors of omission; Errors of commission; Error forcing context); and Overview and brief assessment of human reliability analysis (Basic characteristics of the methods; Assets and drawbacks of the use of each of HRA method; History and prospects of the use of the methods). (P.A.)
Reliability assessment of Indian Point Unit 3 containment structure under combined loads
International Nuclear Information System (INIS)
Hwang, H.; Shinozuka, M.; Kawakami, J.; Reich, M.
1984-01-01
In the current design criteria, the load combinations specified for design of concrete containment structures are in the deterministic format. However, by applying the probability-based reliability analysis method developed by BNL to the concrete containment structures designed according to the criteria, it is possible to evaluate the reliability levels implied in the current design criteria. For this purpose, the reliability analysis is applied to the Indian Point Unit No. 3 containment. The details of the containment structure such as the geometries and the rebar arrangements, etc., are taken from the working drawings and the Final Safety Analysis Report. Three kinds of loads are considered in the reliability analysis. They are, dead load, accidental pressure due to a large LOCA, and earthquake ground acceleration. This paper presents the reliability analysis results of the Indian Point Unit 3 containment subjected to all combinations of loads
Analysis of complete logical structures in system reliability assessment
International Nuclear Information System (INIS)
Amendola, A.; Clarotti, C.A.; Contini, S.; Spizzichino, F.
1980-01-01
The application field of the fault-tree techniques has been explored in order to assess whether the AND-OR structures covered all possible actual binary systems. This resulted in the identification of various situations requiring the complete AND-OR-NOT structures for their analysis. We do not use the term non-coherent for such cases, since the monotonicity or not of a structure function is not a characteristic of a system, but of the particular top event being examined. The report presents different examples of complete fault-trees, which can be examined according to different degrees of approximation. In fact, the exact analysis for the determination of the smallest irredundant bases is very time consuming and actually necessary only in some particular cases (multi-state systems, incidental situations). Therefore, together with the exact procedure, the report shows two different methods of logical analysis that permit the reduction of complete fault-trees to AND-OR structures. Moreover, it discusses the problems concerning the evaluation of the probability distribution of the time to first top event occurrence, once the hypothesis of structure function monotonicity is removed
Design Protocols and Analytical Strategies that Incorporate Structural Reliability Models
Duffy, Stephen F.
1997-01-01
Al single crystal turbine blade material; map a simplistic failure strength envelope of the material; develop a statistically based reliability computer algorithm, verify the reliability model and computer algorithm, and model stator vanes for rig tests. Thus establishing design protocols that enable the engineer to analyze and predict the mechanical behavior of ceramic composites and intermetallics would mitigate the prototype (trial and error) approach currently used by the engineering community. The primary objective of the research effort supported by this short term grant is the continued creation of enabling technologies for the macroanalysis of components fabricated from ceramic composites and intermetallic material systems. The creation of enabling technologies aids in shortening the product development cycle of components fabricated from the new high technology materials.
A New Approach to Structural Reliability in Fatigue Failure
1998-03-01
6. AUTHOR(S) Dr. Sia Nemat-Nasser (PI) Dr. Joseph Zarka 7. PERFORMING ORGANIZATION NAMES(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION UniveBity of...their own problems. IV PUBLICATIONS Huang, J., J. Zarka and P. Navidi, "A New Approach in Relaibility of Welded Structures," Proceedings of the ASCE
Micro-structural reliability design of brittle materials
Czech Academy of Sciences Publication Activity Database
Strnadel, B.; Byczanski, Petr
2007-01-01
Roč. 74, č. 11 (2007), s. 1825-1836 ISSN 0013-7944 R&D Projects: GA ČR(CZ) GA106/06/0646 Institutional research plan: CEZ:AV0Z30860518 Keywords : Cleavage strength * Brittle fracture * Fracture toughness Subject RIV: JJ - Other Materials Impact factor: 1.227, year: 2007 www.elsevier.com/locate/engfracmech
A reliability analysis framework with Monte Carlo simulation for weld structure of crane's beam
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 Structural Systems with regard to Permanent Displacements
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Thoft-Christensen, Palle
1991-01-01
approach - a differential equation approach - a superposition approach - the simple method These three approaches are described in Sørensen & Thoft-Christensen [5], Sørensen et al. [6] and Sørensen & Thoft-Christensen [7]. It is assumed that the structural system can be modelled by a multi-linear elastic......In this paper the problem of estimating the accumulated permanent displacements of an offshore platform during one storm is considered. For dynamically sensitive structural systems subjected to wave loads this problem is generally very difficult. However, for dynamic insensitive systems some...... methods/experience related to permanent deformations are described in Grinda et al. [1] and Papadrakakis & Loukakis [2]. For general dynamic systems modelled by one-degree-of-freedom (and two-degrees-of freedom) systems a number of methods exist, see e.g. Nielsen et al. [3] and Toro & Cornell [4]. However...
A Structural Reliability Business Process Modelling with System Dynamics Simulation
Lam, C. Y.; Chan, S. L.; Ip, W. H.
2010-01-01
Business activity flow analysis enables organizations to manage structured business processes, and can thus help them to improve performance. The six types of business activities identified here (i.e., SOA, SEA, MEA, SPA, MSA and FIA) are correlated and interact with one another, and the decisions from any business activity form feedback loops with previous and succeeding activities, thus allowing the business process to be modelled and simulated. For instance, for any company that is eager t...
Structural similarity image quality reliability: Determining parameters and window size
Silvestre-Blanes, Javier
2011-01-01
The need to obtain objective values of the quality of distorted images with respect to the original is fundamental in multimedia and image processing applications. It is generally required that this value correlates well with the human vision system (HVS). In spite of the properties and the general use of the mean square error (MSE) measurement, this has a poor correlation with HSV, which has led to the development of methods such as structural similarity (SSIM). This metric improves the corr...
Application of response surfaces for reliability analysis of marine structures
International Nuclear Information System (INIS)
Leira, Bernt J.; Holmas, Tore; Herfjord, Kjell
2005-01-01
Marine structures subjected to multiple environmental loads (i.e. waves, current, wind) are considered. These loads are characterized by a set of corresponding parameters. The structural fatigue damage and long-term response are expressed in terms of these environmental parameters based on application of polynomial response surfaces. For both types of analysis, an integration across the range of variation for all the environmental parameters is required. The location of the intervals which give rise to the dominant contribution for these integrals depends on the relative magnitude of the coefficients defining the polynomials. The required degree of numerical subdivision in order to obtain accurate results is also of interest. These issues are studied on a non-dimensional form. The loss of accuracy which results when applying response surfaces of too low order is also investigated. Response surfaces with cut-off limits at specific lower-bound values for the environmental parameters are further investigated. Having obtained general expressions on non-dimensional form, examples which correspond to specific response quantities for marine structures are considered. Typical values for the polynomial coefficients, and for the statistical distributions representing the environmental parameters, are applied. Convergence studies are subsequently performed for the particular example response quantities in order to make comparison with the general formulation. For the extreme response, the application of 'extreme contours' obtained from the statistical distributions of the environmental parameters is explored
International Nuclear Information System (INIS)
Maier, H.R.; Nink, H.; Krauth, A.
1977-01-01
A prediction of the reliability of structural components requires the definition of transfer data from the combination of materials data, design criteria and application conditions. The determination and transfer of strength data are one unit and therefore similar approximations are necessary. The influence of loading conditions, proof testing and analysing methods is explained with bending tests of rectangular specimens and burst tests of big tubes at room temperature. The drop in strength from 180 N/mm 2 to 50 N/mm 2 via a size factor of 10 5 is predicted and experimentally verified with the most simple statistical extension. The results have been applied to special problems of stress concentrations and give conclusions for test techniques and design fundamentals. (orig.) [de
Hedlund, Ann; Ateg, Mattias; Andersson, Ing-Marie; Rosén, Gunnar
2010-04-01
Workers' motivation to actively take part in improvements to the work environment is assumed to be important for the efficiency of investments for that purpose. That gives rise to the need for a tool to measure this motivation. A questionnaire to measure motivation for improvements to the work environment has been designed. Internal consistency and test-retest reliability of the domains of the questionnaire have been measured, and the factorial structure has been explored, from the answers of 113 employees. The internal consistency is high (0.94), as well as the correlation for the total score (0.84). Three factors are identified accounting for 61.6% of the total variance. The questionnaire can be a useful tool in improving intervention methods. The expectation is that the tool can be useful, particularly with the aim of improving efficiency of companies' investments for work environment improvements. Copyright 2010 Elsevier Ltd. All rights reserved.
Structural and reliability analysis of quality of relationship index in cancer patients.
Cousson-Gélie, Florence; de Chalvron, Stéphanie; Zozaya, Carole; Lafaye, Anaïs
2013-01-01
Among psychosocial factors affecting emotional adjustment and quality of life, social support is one of the most important and widely studied in cancer patients, but little is known about the perception of support in specific significant relationships in patients with cancer. This study examined the psychometric properties of the Quality of Relationship Inventory (QRI) by evaluating its factor structure and its convergent and discriminant validity in a sample of cancer patients. A total of 388 patients completed the QRI. Convergent validity was evaluated by testing the correlations between the QRI subscales and measures of general social support, anxiety and depression symptoms. Discriminant validity was examined by testing group comparison. The QRI's longitudinal invariance across time was also tested. Principal axis factor analysis with promax rotation identified three factors accounting for 42.99% of variance: perceived social support, depth, and interpersonal conflict. Estimates of reliability with McDonald's ω coefficient were satisfactory for all the QRI subscales (ω ranging from 0.75 - 0.85). Satisfaction from general social support was negatively correlated with the interpersonal conflict subscale and positively with the depth subscale. The interpersonal conflict and social support scales were correlated with depression and anxiety scores. We also found a relative stability of QRI subscales (measured 3 months after the first evaluation) and differences between partner status and gender groups. The Quality of Relationship Inventory is a valid tool for assessing the quality of social support in a particular relationship with cancer patients.
A reliability program for emergency diesel generators at nuclear power plants: Program structure
International Nuclear Information System (INIS)
Lofgren, E.V.; DeMoss, G.M.; Fragola, J.R.; Appignani, P.L.; Delarche, G.; Boccio, J.
1988-04-01
The purpose of this report is to provide technical guidelines for NRC staff use in the development of positions for evaluating emergency diesel generator (EDG) reliability programs. Such reviews will likely result following resolution of USI A-44 and GSI B-56. The diesel generator reliability program is a management system for achieving and maintaining a selected (or target) level of reliability. This can be achieved by: (1) understanding the factors that control the EDG reliability and (2) then applying reliability and maintenance techniques in the proper proportion to achieve selected performance goals. The concepts and guidelines discussed in this report are concepts and approaches that have been successful in applications where high levels of reliability must be maintained. Both an EDG reliability program process and a set of review items for NRC use are provided. The review items represent a checklist for reviewing EDG reliability programs. They do not, in themselves, constitute a reliability program. Rather, the review items are those distinctive features of a reliability program that must be present for the program to be effective
Data mining-based coefficient of influence factors optimization of test paper reliability
Xu, Peiyao; Jiang, Huiping; Wei, Jieyao
2018-05-01
Test is a significant part of the teaching process. It demonstrates the final outcome of school teaching through teachers' teaching level and students' scores. The analysis of test paper is a complex operation that has the characteristics of non-linear relation in the length of the paper, time duration and the degree of difficulty. It is therefore difficult to optimize the coefficient of influence factors under different conditions in order to get text papers with clearly higher reliability with general methods [1]. With data mining techniques like Support Vector Regression (SVR) and Genetic Algorithm (GA), we can model the test paper analysis and optimize the coefficient of impact factors for higher reliability. It's easy to find that the combination of SVR and GA can get an effective advance in reliability from the test results. The optimal coefficient of influence factors optimization has a practicability in actual application, and the whole optimizing operation can offer model basis for test paper analysis.
Comparing Factor Structures of Adolescent Psychopathology
Verona, Edelyn; Javdani, Shabnam; Sprague, Jenessa
2011-01-01
Research on the structure of adolescent psychopathology can provide information on broad factors that underlie different forms of maladjustment in youths. Multiple studies from the literature on adult populations suggest that 2 factors, Internalizing and Externalizing, meaningfully comprise the factor structure of adult psychopathology (e.g.,…
Reliability Assessment of a Bridge Structure Subjected to Chloride Attack
DEFF Research Database (Denmark)
Leira, Bernt J.; Thöns, Sebastian; Nielsen, Michael Havbro Faber
2018-01-01
Prediction of the service lifetime of concrete structures with respect to chloride ingress involves a number of parameters that are associated with large uncertainties. Hence, full-scale measurements are strongly in demand. This paper begins by summarizing statistical distributions based on measu......Prediction of the service lifetime of concrete structures with respect to chloride ingress involves a number of parameters that are associated with large uncertainties. Hence, full-scale measurements are strongly in demand. This paper begins by summarizing statistical distributions based...... on measurements taken from the Gimsøystraumen Bridge in Norway. A large number of chloride profiles are available based on concrete coring samples, and for each of these profiles the diffusion coefficient and surface concentration (due to sea spray) are estimated. Extensive measurements of the concrete cover...... depth are also performed. The probability distributions are input into a prediction model for chloride concentration at the steel reinforcement. By also introducing the critical chloride concentration as a random variable, the probability of exceeding the critical threshold is determined as a function...
African Journals Online (AJOL)
eobe
Corresponding author, Tel: +234-703. RELIABILITY .... V , , given by the code of practice. However, checks must .... an optimization procedure over the failure domain F corresponding .... of Concrete Members based on Utility Theory,. Technical ...
Soil-structure interaction effects on the reliability evaluation of reactor containments
International Nuclear Information System (INIS)
Pires, J.; Hwang, H.; Reich, M.
1986-01-01
The probability-based method for the seismic reliability assessment of nuclear structures, which has been developed at Brookhaven National Laboratory (BNL), is extended to include the effects of soil-structure interaction. A reinforced concrete containment building is analyzed in order to examine soil-structure interaction effects on: (1) structural fragilities; (2) floor response spectra statistics; and (3) correlation coefficients for total acceleration responses at specified structural locations
Carvalho, Teresa; Cunha, Marina; Pinto-Gouveia, José; Duarte, Joana
2015-03-30
The PTSD Checklist-Military Version (PCL-M) is a brief self-report instrument widely used to assess Post-traumatic Stress Disorder (PTSD) symptomatology in war Veterans, according to DSM-IV. This study sought out to explore the factor structure and reliability of the Portuguese version of the PCL-M. A sample of 660 Portuguese Colonial War Veterans completed the PCL-M. Several Confirmatory Factor Analyses were conducted to test different structures for PCL-M PTSD symptoms. Although the respecified first-order four-factor model based on King et al.'s model showed the best fit to the data, the respecified first and second-order models based on the DSM-IV symptom clusters also presented an acceptable fit. In addition, the PCL-M showed adequate reliability. The Portuguese version of the PCL-M is thus a valid and reliable measure to assess the severity of PTSD symptoms as described in DSM-IV. Its use with Portuguese Colonial War Veterans may ease screening of possible PTSD cases, promote more suitable treatment planning, and enable monitoring of therapeutic outcomes. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Analysis methods for structure reliability of piping components
International Nuclear Information System (INIS)
Schimpfke, T.; Grebner, H.; Sievers, J.
2004-01-01
In the frame of the German reactor safety research program of the Federal Ministry of Economics and Labour (BMWA) GRS has started to develop an analysis code named PROST (PRObabilistic STructure analysis) for estimating the leak and break probabilities of piping systems in nuclear power plants. The long-term objective of this development is to provide failure probabilities of passive components for probabilistic safety analysis of nuclear power plants. Up to now the code can be used for calculating fatigue problems. The paper mentions the main capabilities and theoretical background of the present PROST development and presents some of the results of a benchmark analysis in the frame of the European project NURBIM (Nuclear Risk Based Inspection Methodologies for Passive Components). (orig.)
Meeting Human Reliability Requirements through Human Factors Design, Testing, and Modeling
Energy Technology Data Exchange (ETDEWEB)
R. L. Boring
2007-06-01
In the design of novel systems, it is important for the human factors engineer to work in parallel with the human reliability analyst to arrive at the safest achievable design that meets design team safety goals and certification or regulatory requirements. This paper introduces the System Development Safety Triptych, a checklist of considerations for the interplay of human factors and human reliability through design, testing, and modeling in product development. This paper also explores three phases of safe system development, corresponding to the conception, design, and implementation of a system.
On the Effect of Security and Communication Factors in the Reliability of Wireless Sensor Networks
Directory of Open Access Journals (Sweden)
Damian Rusinek
2014-03-01
Full Text Available The ensuring reliability of wireless sensor networks (WSN is one of most important problems to be solved. In this article, the influence of the security and communication factors in the reliability of Wireless Sensor Networks was analyzed. Balancing security against performance in WSN is another issue to be solved. These factors should be considered during security analysis of quality of protection of realized protocol. In the article, we analyze wireless sensor network where hierarchical topologies is implemented with high performance routing sensors that forward big amount of data. We present the experiment results which were performed by high-performance Imote2 sensor platform and TinyOS operating system.
Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization
More, Sushant N.
New insights into the inter-nucleon interactions, developments in many-body technology, and the surge in computational capabilities has led to phenomenal progress in low-energy nuclear physics in the past few years. Nonetheless, many calculations still lack a robust uncertainty quantification which is essential for making reliable predictions. In this work we investigate two distinct sources of uncertainty and develop ways to account for them. Harmonic oscillator basis expansions are widely used in ab-initio nuclear structure calculations. Finite computational resources usually require that the basis be truncated before observables are fully converged, necessitating reliable extrapolation schemes. It has been demonstrated recently that errors introduced from basis truncation can be taken into account by focusing on the infrared and ultraviolet cutoffs induced by a truncated basis. We show that a finite oscillator basis effectively imposes a hard-wall boundary condition in coordinate space. We accurately determine the position of the hard-wall as a function of oscillator space parameters, derive infrared extrapolation formulas for the energy and other observables, and discuss the extension of this approach to higher angular momentum and to other localized bases. We exploit the duality of the harmonic oscillator to account for the errors introduced by a finite ultraviolet cutoff. Nucleon knockout reactions have been widely used to study and understand nuclear properties. Such an analysis implicitly assumes that the effects of the probe can be separated from the physics of the target nucleus. This factorization between nuclear structure and reaction components depends on the renormalization scale and scheme, and has not been well understood. But it is potentially critical for interpreting experiments and for extracting process-independent nuclear properties. We use a class of unitary transformations called the similarity renormalization group (SRG) transformations to
Reliability of a structured interview for admission to an emergency medicine residency program.
Blouin, Danielle
2010-10-01
Interviews are most important in resident selection. Structured interviews are more reliable than unstructured ones. We sought to measure the interrater reliability of a newly designed structured interview during the selection process to an Emergency Medicine residency program. The critical incident technique was used to extract the desired dimensions of performance. The interview tool consisted of 7 clinical scenarios and 1 global rating. Three trained interviewers marked each candidate on all scenarios without discussing candidates' responses. Interitem consistency and estimates of variance were computed. Twenty-eight candidates were interviewed. The generalizability coefficient was 0.67. Removing the central tendency ratings increased the coefficient to 0.74. Coefficients of interitem consistency ranged from 0.64 to 0.74. The structured interview tool provided good although suboptimal interrater reliability. Increasing the number of scenarios improves reliability as does applying differential weights to the rating scale anchors. The latter would also facilitate the identification of those candidates with extreme ratings.
Development of a reliability-analysis method for category I structures
International Nuclear Information System (INIS)
Shinozuka, M.; Kako, T.; Hwang, H.; Reich, M.
1983-01-01
The present paper develops a reliability analysis method for category I nuclear structures, particularly for reinforced concrete containment structures subjected to various load combinations. The loads considered here include dead loads, accidental internal pressure and earthquake ground acceleration. For mathematical tractability, an earthquake occurrence is assumed to be governed by the Poisson arrival law, while its acceleration history is idealized as a Gaussian vector process of finite duration. A vector process consists of three component processes, each with zero mean. The second order statistics of this process are specified by a three-by-three spectral density matrix with a multiplying factor representing the overall intensity of the ground acceleration. With respect to accidental internal pressure, the following assumptions are made: (a) it occurs in accordance with the Poisson law; (b) its intensity and duration are random; and (c) its temporal rise and fall behaviors are such that a quasi-static structural analysis applies. A dead load is considered to be a deterministic constant
Prószyński, W.; Kwaśniak, M.
2018-03-01
A global measure of observation correlations in a network is proposed, together with the auxiliary indices related to non-diagonal elements of the correlation matrix. Based on the above global measure, a specific representation of the correlation matrix is presented, being the result of rigorously proven theorem formulated within the present research. According to the theorem, each positive definite correlation matrix can be expressed by a scale factor and a so-called internal weight matrix. Such a representation made it possible to investigate the structure of the basic reliability measures with regard to observation correlations. Numerical examples carried out for two test networks illustrate the structure of those measures that proved to be dependent on global correlation index. Also, the levels of global correlation are proposed. It is shown that one can readily find an approximate value of the global correlation index, and hence the correlation level, for the expected values of auxiliary indices being the only knowledge about a correlation matrix of interest. The paper is an extended continuation of the previous study of authors that was confined to the elementary case termed uniform correlation. The extension covers arbitrary correlation matrices and a structure of correlation effect.
LIF: A new Kriging based learning function and its application to structural reliability analysis
International Nuclear Information System (INIS)
Sun, Zhili; Wang, Jian; Li, Rui; Tong, Cao
2017-01-01
The main task of structural reliability analysis is to estimate failure probability of a studied structure taking randomness of input variables into account. To consider structural behavior practically, numerical models become more and more complicated and time-consuming, which increases the difficulty of reliability analysis. Therefore, sequential strategies of design of experiment (DoE) are raised. In this research, a new learning function, named least improvement function (LIF), is proposed to update DoE of Kriging based reliability analysis method. LIF values how much the accuracy of estimated failure probability will be improved if adding a given point into DoE. It takes both statistical information provided by the Kriging model and the joint probability density function of input variables into account, which is the most important difference from the existing learning functions. Maximum point of LIF is approximately determined with Markov Chain Monte Carlo(MCMC) simulation. A new reliability analysis method is developed based on the Kriging model, in which LIF, MCMC and Monte Carlo(MC) simulation are employed. Three examples are analyzed. Results show that LIF and the new method proposed in this research are very efficient when dealing with nonlinear performance function, small probability, complicated limit state and engineering problems with high dimension. - Highlights: • Least improvement function (LIF) is proposed for structural reliability analysis. • LIF takes both Kriging based statistical information and joint PDF into account. • A reliability analysis method is constructed based on Kriging, MCS and LIF.
Laidoune, Abdelbaki; Rahal Gharbi, Med El Hadi
2016-09-01
The influence of sociocultural factors on human reliability within an open sociotechnical systems is highlighted. The design of such systems is enhanced by experience feedback. The study was focused on a survey related to the observation of working cases, and by processing of incident/accident statistics and semistructured interviews in the qualitative part. In order to consolidate the study approach, we considered a schedule for the purpose of standard statistical measurements. We tried to be unbiased by supporting an exhaustive list of all worker categories including age, sex, educational level, prescribed task, accountability level, etc. The survey was reinforced by a schedule distributed to 300 workers belonging to two oil companies. This schedule comprises 30 items related to six main factors that influence human reliability. Qualitative observations and schedule data processing had shown that the sociocultural factors can negatively and positively influence operator behaviors. The explored sociocultural factors influence the human reliability both in qualitative and quantitative manners. The proposed model shows how reliability can be enhanced by some measures such as experience feedback based on, for example, safety improvements, training, and information. With that is added the continuous systems improvements to improve sociocultural reality and to reduce negative behaviors.
Boermans, M.A.; Kattenberg, M.A.C.
2011-01-01
We show how to estimate a Cronbach's alpha reliability coefficient in Stata after running a principal component or factor analysis. Alpha evaluates to what extent items measure the same underlying content when the items are combined into a scale or used for latent variable. Stata allows for testing
Coloured Letters and Numbers (CLaN): A reliable factor-analysis based synaesthesia questionnaire
Rothen Nicolas; Tsakanikos Elias; Meier Beat; Ward Jamie
2013-01-01
Synaesthesia is a heterogeneous phenomenon even when considering one particular sub type. The purpose of this study was to design a reliable and valid questionnaire for grapheme colour synaesthesia that captures this heterogeneity. By the means of a large sample of 628 synaesthetes and a factor analysis we created the Coloured Letters and Numbers (CLaN) questionnaire with 16 items loading on 4 different factors (i.e. localisation automaticity/attention deliberate use and longitudinal changes)...
Recent Advances in Optimal Design of Structures from a Reliability Point of View
DEFF Research Database (Denmark)
Thoft-Christensen, Palle; Sørensen, John Dalsgaard
1987-01-01
-Christensen and Baker[4] and Madsen et al.[5]. Next a heuristic method, the so-called ß-unzipping method[6] is mentioned. This method can be used to estimate the reliability of a structural system if some modelling assumptions are fulfilled. In the third section some elements of structural optimisation theory...... section. First, a short review of the reliability theory for structural elements (e.g., beams and tubular joints) based on the so-called ß-index philosophy (Cornell[1], Ditlevsen[2], and Hasofer and Lind[3]) is given. Detailed descriptions are given in textbooks such as those by Thoft...
Structural system reliability calculation using a probabilistic fault tree analysis method
Torng, T. Y.; Wu, Y.-T.; Millwater, H. R.
1992-01-01
The development of a new probabilistic fault tree analysis (PFTA) method for calculating structural system reliability is summarized. The proposed PFTA procedure includes: developing a fault tree to represent the complex structural system, constructing an approximation function for each bottom event, determining a dominant sampling sequence for all bottom events, and calculating the system reliability using an adaptive importance sampling method. PFTA is suitable for complicated structural problems that require computer-intensive computer calculations. A computer program has been developed to implement the PFTA.
International Nuclear Information System (INIS)
Stepanek, P.; Stastnik, S.; Salajka, V.; Hradil, P.; Skolar, J.; Chlanda, V.
2003-01-01
The contribution presents some aspects of the static reliability of concrete structures under temperature effects and under mechanical loading. The mathematical model of a load-bearing concrete structure was performed using the FEM method. The temperature field and static stress that generated states of stress were taken into account. A brief description of some aspects of evaluation of the reliability within the primary circuit concrete structures is stated. The knowledge of actual physical and mechanical characteristics and chemical composition of concrete were necessary for obtaining correct results of numerical analysis. (author)
International Nuclear Information System (INIS)
Lucia, A.C.
1984-01-01
The probability of failure of a structural component can be estimated by either statistical methods or a probabilistic structural reliability approach (where the failure is seen as a level crossing of a damage stochastic process which develops in space and in time). The probabilistic approach has the advantage that it makes available not only an absolute value of the failure probability but also a lot of additional information. The disadvantage of the probabilistic approach is its complexity. It is discussed for the following situations: reliability of a structural component, material properties, data for fatigue crack growth evaluation, a bench mark exercise on reactor pressure vessel failure probability computation, and non-destructive examination for assuring a given level of structural reliability. (U.K.)
Safety management of pipelines based on structural reliability: historical perspective and progress
Energy Technology Data Exchange (ETDEWEB)
Beck, Andre Teofilo; Bazan, Felipe Alexander Vargas [Universidade de Sao Paulo (USP), SP (Brazil); Mendes, Renato [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Donato, Guilherme [Petroleo Brasileiro S.A. (PETROBRAS/CENPES), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas e Desenvolvimento; Gardiner, Michael [GL Noble Denton, Loughborough (United Kingdom)
2012-07-01
Since the early beginnings in the sixties and seventies, Structural Reliability theory has reached a mature stage encompassing solid theoretical developments and increasing practical applications. Structural reliability methods have permeated the engineering profession, finding applications in code calibration, structural optimization, life extension of existing structures, life-cycle management of infrastructure risks and costs, and so on. This review paper shows that the ground work for Reliability Based Design and Assessment (RBDA) of onshore pipeline systems is already developed. Hence, this allows the economic management of the risks involved in operation of pipeline systems. It is shown that RBDA is a rational tool to safely manage the operational life of pipeline systems, optimizing initial design and the expenditures in inspection and maintenance operations. (author)
Some recent developments in the risk- and reliability analysis of structures
International Nuclear Information System (INIS)
Bauer, J.; Choi, H.S.; Kappler, H.; Melzer, H.J.; Panggabean, H.; Reichmann, K.H.; Schueller, G.I.; Schwarz, R.F.
1979-01-01
This report consists of six contributions divided into four general topics. While Part I concentrates on the development of Analytical Methods in Structural Reliability, Part II to IV are devoted to the application of these methods to Offshore-, Nuclear - and generally to Wind- and Earthquake Exposed Structures. (orig.) [de
Directory of Open Access Journals (Sweden)
Ertekin Öztekin Öztekin
2015-12-01
Full Text Available Design of the distance of bolts to each other and design of the distance of bolts to the edge of connection plates are made based on minimum and maximum boundary values proposed by structural codes. In this study, reliabilities of those distances were investigated. For this purpose, loading types, bolt types and plate thicknesses were taken as variable parameters. Monte Carlo Simulation (MCS method was used in the reliability computations performed for all combination of those parameters. At the end of study, all reliability index values for all those distances were presented in graphics and tables. Results obtained from this study compared with the values proposed by some structural codes and finally some evaluations were made about those comparisons. Finally, It was emphasized in the end of study that, it would be incorrect of the usage of the same bolt distances in the both traditional designs and the higher reliability level designs.
Reliability-based load and resistance factor design for piping: an exploratory case study
International Nuclear Information System (INIS)
Gupta, Abhinav; Choi, Byounghoan
2003-01-01
This paper presents an exploratory case study on the application of Load and Resistance Factor Design (LRFD) approach to the Section III of ASME Boiler and Pressure Vessel code for piping design. The failure criterion for defining the performance function is considered as plastic instability. Presently used design equation is calibrated by evaluating the minimum reliability levels associated with it. If the target reliability in the LRFD approach is same as that evaluated for the presently used design equation, it is shown that the total safety factors for the two design equations are identical. It is observed that the load and resistance factors are not dependent upon the diameter to thickness ratio. A sensitivity analysis is also conducted to study the variations in the load and resistance factors due to changes in (a) coefficients of variation for pressure, moment, and ultimate stress, (b) ratio of mean design pressure to mean design moment, (c) distribution types used for characterizing the random variables, and (d) statistical correlation between random variables. It is observed that characterization of random variables by log-normal distribution is reasonable. Consideration of statistical correlation between the ultimate stress and section modulus gives higher values of the load factor for pressure but lower value for the moment than the corresponding values obtained by considering the variables to be uncorrelated. Since the effect of statistical correlation on the load and resistance factors is relatively insignificant for target reliability values of practical interest, the effect of correlated variables may be neglected
Directory of Open Access Journals (Sweden)
Bruce Weaver
2014-09-01
Full Text Available Missing data is a frequent problem for researchers conducting exploratory factor analysis (EFA or reliability analysis. The SPSS FACTOR procedure allows users to select listwise deletion, pairwise deletion or mean substitution as a method for dealing with missing data. The shortcomings of these methods are well-known. Graham (2009 argues that a much better way to deal with missing data in this context is to use a matrix of expectation maximization (EM covariances(or correlations as input for the analysis. SPSS users who have the Missing Values Analysis add-on module can obtain vectors ofEM means and standard deviations plus EM correlation and covariance matrices via the MVA procedure. But unfortunately, MVA has no /MATRIX subcommand, and therefore cannot write the EM correlations directly to a matrix dataset of the type needed as input to the FACTOR and RELIABILITY procedures. We describe two macros that (in conjunction with an intervening MVA command carry out the data management steps needed to create two matrix datasets, one containing EM correlations and the other EM covariances. Either of those matrix datasets can then be used asinput to the FACTOR procedure, and the EM correlations can also be used as input to RELIABILITY. We provide an example that illustrates the use of the two macros to generate the matrix datasets and how to use those datasets as input to the FACTOR and RELIABILITY procedures. We hope that this simple method for handling missing data will prove useful to both students andresearchers who are conducting EFA or reliability analysis.
DEFF Research Database (Denmark)
Bech, B; Lönn, L; Falkenberg, M
2011-01-01
Objectives To study the construct validity and reliability of a novel endovascular global rating scale, Structured Assessment of endoVascular Expertise (SAVE). Design A Clinical, experimental study. Materials Twenty physicians with endovascular experiences ranging from complete novices to highly....... Validity was analysed by correlating experience with performance results. Reliability was analysed according to generalisability theory. Results The mean score on the 29 items of the SAVE scale correlated well with clinical experience (R = 0.84, P ... with clinical experience (R = -0.53, P validity and reliability of assessment with the SAVE scale was high when applied to performances in a simulation setting with advanced realism. No ceiling effect...
Optimised and balanced structural and system reliability of offshore wind turbines. An account
Energy Technology Data Exchange (ETDEWEB)
Tarp-Johansen, N.J.; Kozine, I. (Risoe National Lab., DTU, Roskilde, (DK)); Rademarkers, L. (Netherlands Energy Research Foundation (NL)); Dalsgaard Soerensen, J. (Aalborg Univ. (DK)) Ronold, K. (Det Norske Veritas (DK))
2005-04-15
This report gives the results of the research project 'Optimised and Uniform Safety and Reliability of Offshore Wind Turbines (an account)'. The main subject of the project has been the account of the state-of-the art of knowledge about, and/or attempts to, harmonisation of the structural reliability of wind turbines, on the one hand, and the reliability of the wind turbine's control/safety system, on the other hand. Within the project some research pointing ahead has also been conducted. (au)
The Role of Human Error in Design, Construction, and Reliability of Marine Structures.
1994-10-01
the fundamental reason for the disparities between computed or notional reliabilities and actuarial relia- bilities. Another important finding from...Marine Structures Lack of recognition of HOE is the fundamental reason for the disparities between computed or notional reliabilities and actuarial ...Conference on Offshore Mechanics and Arctic Engineering, ASME Paper No. OMAE-92-1372, Calgary, Alberta, Canada. Bea, R. G., et al. (1994). "Quality Assurance
Suen, Yi-Nam; Cerin, Ester; Barnett, Anthony; Huang, Wendy Y J; Mellecker, Robin R
2017-09-01
Valid instruments of parenting practices related to children's physical activity (PA) are essential to understand how parents affect preschoolers' PA. This study developed and validated a questionnaire of PA-related parenting practices for Chinese-speaking parents of preschoolers in Hong Kong. Parents (n = 394) completed a questionnaire developed using findings from formative qualitative research and literature searches. Test-retest reliability was determined on a subsample (n = 61). Factorial validity was assessed using confirmatory factor analysis. Subscale internal consistency was determined. The scale of parenting practices encouraging PA comprised 2 latent factors: Modeling, structure and participatory engagement in PA (23 items), and Provision of appropriate places for child's PA (4 items). The scale of parenting practices discouraging PA scale encompassed 4 latent factors: Safety concern/overprotection (6 items), Psychological/behavioral control (5 items), Promoting inactivity (4 items), and Promoting screen time (2 items). Test-retest reliabilities were moderate to excellent (0.58 to 0.82), and internal subscale reliabilities were acceptable (0.63 to 0.89). We developed a theory-based questionnaire for assessing PA-related parenting practices among Chinese-speaking parents of Hong Kong preschoolers. While some items were context and culture specific, many were similar to those previously found in other populations, indicating a degree of construct generalizability across cultures.
Human and organization factors: engineering operating safety into offshore structures
International Nuclear Information System (INIS)
Bea, Robert G.
1998-01-01
History indicates clearly that the safety of offshore structures is determined primarily by the humans and organizations responsible for these structures during their design, construction, operation, maintenance, and decommissioning. If the safety of offshore structures is to be preserved and improved, then attention of engineers should focus on to how to improve the reliability of the offshore structure 'system,' including the people that come into contact with the structure during its life-cycle. This article reviews and discusss concepts and engineering approaches that can be used in such efforts. Two specific human factor issues are addressed: (1) real-time management of safety during operations, and (2) development of a Safety Management Assessment System to help improve the safety of offshore structures
Pertermann, I.; Puthli, R.; Ummenhofer, T.; Vrouwenvelder, A.C.W.M.
2012-01-01
The Eurocode EN 1990 [1] Annex B Clause B.3 allows a risk oriented differentiation of the reliability levels with the definition of different consequences classes CC1 to CC3. This can occur through decrease or increase of the safety factor for either the action or the resistance. Should the
Energy Technology Data Exchange (ETDEWEB)
Vasconcelos, Vanderley de; Silva, Eliane Magalhaes Pereira da; Costa, Antonio Carlos Lopes da; Reis, Sergio Carneiro dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: vasconv@cdtn.br, e-mail: silvaem@cdtn.br, e-mail: aclc@cdtn.br, e-mail: reissc@cdtn.br
2009-07-01
Nuclear energy has an important engineering legacy to share with the conventional industry. Much of the development of the tools related to safety, reliability, risk management, and human factors are associated with nuclear plant processes, mainly because the public concern about nuclear power generation. Despite the close association between these subjects, there are some important different approaches. The reliability engineering approach uses several techniques to minimize the component failures that cause the failure of the complex systems. These techniques include, for instance, redundancy, diversity, standby sparing, safety factors, and reliability centered maintenance. On the other hand system safety is primarily concerned with hazard management, that is, the identification, evaluation and control of hazards. Rather than just look at failure rates or engineering strengths, system safety would examine the interactions among system components. The events that cause accidents may be complex combinations of component failures, faulty maintenance, design errors, human actions, or actuation of instrumentation and control. Then, system safety deals with a broader spectrum of risk management, including: ergonomics, legal requirements, quality control, public acceptance, political considerations, and many other non-technical influences. Taking care of these subjects individually can compromise the completeness of the analysis and the measures associated with both risk reduction, and safety and reliability increasing. Analyzing together the engineering systems and controls of a nuclear facility, their management systems and operational procedures, and the human factors engineering, many benefits can be realized. This paper proposes an integration of these issues based on the application of systems theory. (author)
International Nuclear Information System (INIS)
Vasconcelos, Vanderley de; Silva, Eliane Magalhaes Pereira da; Costa, Antonio Carlos Lopes da; Reis, Sergio Carneiro dos
2009-01-01
Nuclear energy has an important engineering legacy to share with the conventional industry. Much of the development of the tools related to safety, reliability, risk management, and human factors are associated with nuclear plant processes, mainly because the public concern about nuclear power generation. Despite the close association between these subjects, there are some important different approaches. The reliability engineering approach uses several techniques to minimize the component failures that cause the failure of the complex systems. These techniques include, for instance, redundancy, diversity, standby sparing, safety factors, and reliability centered maintenance. On the other hand system safety is primarily concerned with hazard management, that is, the identification, evaluation and control of hazards. Rather than just look at failure rates or engineering strengths, system safety would examine the interactions among system components. The events that cause accidents may be complex combinations of component failures, faulty maintenance, design errors, human actions, or actuation of instrumentation and control. Then, system safety deals with a broader spectrum of risk management, including: ergonomics, legal requirements, quality control, public acceptance, political considerations, and many other non-technical influences. Taking care of these subjects individually can compromise the completeness of the analysis and the measures associated with both risk reduction, and safety and reliability increasing. Analyzing together the engineering systems and controls of a nuclear facility, their management systems and operational procedures, and the human factors engineering, many benefits can be realized. This paper proposes an integration of these issues based on the application of systems theory. (author)
The Factor Structure in Equity Options
DEFF Research Database (Denmark)
Christoffersen, Peter; Fournier, Mathieu; Jacobs, Kris
2018-01-01
Equity options display a strong factor structure. The first principal components of the equity volatility levels, skews, and term structures explain a substantial fraction of the crosssectional variation. Furthermore, these principal components are highly correlated with the S&P 500 index option...... volatility, skew, and term structure, respectively. We develop an equity option valuation model that captures this factor structure. The model predicts that firms with higher market betas have higher implied volatilities, steeper moneyness slopes, and a term structure that covaries more with the market...
The Factor Structure in Equity Options
DEFF Research Database (Denmark)
Christoffersen, Peter; Fournier, Mathieu; Jacobs, Kris
Equity options display a strong factor structure. The first principal components of the equity volatility levels, skews, and term structures explain a substantial fraction of the cross-sectional variation. Furthermore, these principal components are highly correlated with the S&P500 index option...... volatility, skew, and term structure respectively. We develop an equity option valuation model that captures this factor structure. The model predicts that firms with higher market betas have higher implied volatilities, steeper moneyness slopes, and a term structure that co-varies more with the market...
Development of reliability-based load and resistance factor design methods for piping
International Nuclear Information System (INIS)
Ayyub, Bilal M.; Hill, Ralph S. III; Balkey, Kenneth R.
2003-01-01
Current American Society of Mechanical Engineers (ASME) nuclear codes and standards rely primarily on deterministic and mechanistic approaches to design. The American Institute of Steel Construction and the American Concrete Institute, among other organizations, have incorporated probabilistic methodologies into their design codes. ASME nuclear codes and standards could benefit from developing a probabilistic, reliability-based, design methodology. This paper provides a plan to develop the technical basis for reliability-based, load and resistance factor design of ASME Section III, Class 2/3 piping for primary loading, i.e., pressure, deadweight and seismic. The plan provides a proof of concept in that LRFD can be used in the design of piping, and could achieve consistent reliability levels. Also, the results from future projects in this area could form the basis for code cases, and additional research for piping secondary loads. (author)
McKinney, Christy M; Harris, T Robert; Caetano, Raul
2009-01-01
Little is known about the reliability of self-reported child physical abuse (CPA) or CPA reporting practices. We estimated reliability and prevalence of self-reported CPA and identified factors predictive of inconsistent CPA reporting among 2,256 participants using surveys administered in 1995 and 2000. Reliability of CPA was fair to moderate (kappa = 0.41). Using a positive report from either survey, the prevalence of moderate (61.8%) and severe (12.0%) CPA was higher than at either survey alone. Compared to consistent reporters of having experienced CPA, inconsistent reporters were less likely to be > or = 30 years old (vs. 18-29) or Black (vs. White) and more likely to have report one type (vs. > or = 2) of CPA. These findings may assist researchers conducting and interpreting studies of CPA.
Lessons learned from the PISC III study of the influence on human factors on inspection reliability
International Nuclear Information System (INIS)
Murgatroyd, R.A.; Worrall, G.M.; Crutzen, S.
1995-01-01
Results from the PISC II Programme suggested that differences existed between manual inspectors in terms of their skills, knowledge and working practices which could exert a significant influence on the reliability on an inspection. Therefore, a programme of work on human reliability studies was initiated in the PISC III Programme as Action 7, with the objectives of studying and identifying causes of variability in inspection activities, and identifying some of the factors influencing the reliability of inspection in industrial conditions. It was foreseen that the information from Action 7 would aid in the development of methods for reducing the incidence of human error in inspection activities. This paper gives a brief summary of the programme and describes the lessons learned as a result of the work. A considerably more detailed description of the work is available as a PISC report. 3 refs, 3 figs
Williams, Janet B W; Kobak, Kenneth A
2008-01-01
The Montgomery-Asberg Depression Rating Scale (MADRS) is often used in clinical trials to select patients and to assess treatment efficacy. The scale was originally published without suggested questions for clinicians to use in gathering the information necessary to rate the items. Structured and semi-structured interview guides have been found to improve reliability with other scales. To describe the development and test-retest reliability of a structured interview guide for the MADRS (SIGMA). A total of 162 test-retest interviews were conducted by 81 rater pairs. Each patient was interviewed twice, once by each rater conducting an independent interview. The intraclass correlation for total score between raters using the SIGMA was r=0.93, Preliability. Use of the SIGMA can result in high reliability of MADRS scores in evaluating patients with depression.
Cioclov, Dimitru Dragos
2013-01-01
Probabilistic methods for failure risk assessment are introduced, with reference to load carrying structures, such as pressure vessels (PV) and components of pipes systems. The definition of the failure risk associated with structural integrity is made in the context of the general approach to structural reliability. Sources of risk are summarily outlined with emphasis on variability and uncertainties (V&U) which might be encountered in the analysis. To highlight the problem, in its practical...
The human factor in operation and maintenance of complex high-reliability systems
International Nuclear Information System (INIS)
Ryan, T.G.
1989-01-01
Human factors issues in probabilistic risk assessment (PRAs) of complex high-reliability systems are addressed. These PRAs influence system operation and technical support programs such as maintainability, test, and surveillance. Using the U.S. commercial nuclear power industry as the setting, the paper addresses the manner in which PRAs currently treat human performance, the state of quantification methods and source data for analyzing human performance, and the role of human factors specialist in the analysis. The paper concludes with a presentation of TALENT, an emerging concept for fully integrating broad-based human factors expertise into the PRA process, is presented. 47 refs
On new cautious structural reliability models in the framework of imprecise probabilities
DEFF Research Database (Denmark)
Utkin, Lev; Kozine, Igor
2010-01-01
measures when the number of events of interest or observations is very small. The main feature of the models is that prior ignorance is not modelled by a fixed single prior distribution, but by a class of priors which is defined by upper and lower probabilities that can converge as statistical data......New imprecise structural reliability models are described in this paper. They are developed based on the imprecise Bayesian inference and are imprecise Dirichlet, imprecise negative binomial, gamma-exponential and normal models. The models are applied to computing cautious structural reliability...
Goode, N; Salmon, P M; Taylor, N Z; Lenné, M G; Finch, C F
2017-10-01
One factor potentially limiting the uptake of Rasmussen's (1997) Accimap method by practitioners is the lack of a contributing factor classification scheme to guide accident analyses. This article evaluates the intra- and inter-rater reliability and criterion-referenced validity of a classification scheme developed to support the use of Accimap by led outdoor activity (LOA) practitioners. The classification scheme has two levels: the system level describes the actors, artefacts and activity context in terms of 14 codes; the descriptor level breaks the system level codes down into 107 specific contributing factors. The study involved 11 LOA practitioners using the scheme on two separate occasions to code a pre-determined list of contributing factors identified from four incident reports. Criterion-referenced validity was assessed by comparing the codes selected by LOA practitioners to those selected by the method creators. Mean intra-rater reliability scores at the system (M = 83.6%) and descriptor (M = 74%) levels were acceptable. Mean inter-rater reliability scores were not consistently acceptable for both coding attempts at the system level (M T1 = 68.8%; M T2 = 73.9%), and were poor at the descriptor level (M T1 = 58.5%; M T2 = 64.1%). Mean criterion referenced validity scores at the system level were acceptable (M T1 = 73.9%; M T2 = 75.3%). However, they were not consistently acceptable at the descriptor level (M T1 = 67.6%; M T2 = 70.8%). Overall, the results indicate that the classification scheme does not currently satisfy reliability and validity requirements, and that further work is required. The implications for the design and development of contributing factors classification schemes are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Xing Jiang
2018-03-01
Full Text Available In recent years, the ultra-high voltage direct current (UHVDC transmission system has been developed rapidly for its significant long-distance, high-capacity and low-loss properties. Equipment failures and overall outages of the UHVDC system have increasingly vital influence on the power supply of the receiving end grid. To improve the reliability level of UHVDC systems, a quantitative selection and configuration approach of redundant structures is proposed in this paper, which is based on multi-state reliability equivalence. Specifically, considering the symmetry characteristic of an UHVDC system, a state space model is established as a monopole rather than a bipole, which effectively reduces the state space dimensions to be considered by deducing the reliability merging operator of two poles. Considering the standby effect of AC filters and the recovery effect of converter units, the number of available converter units and corresponding probability are expressed with in universal generating function (UGF form. Then, a sensitivity analysis is performed to quantify the impact of component reliability parameters on system reliability and determine the most specific devices that should be configured in the redundant structure. Finally, a cost-benefit analysis is utilized to help determine the optimal scheme of redundant devices. Case studies are conducted to demonstrate the effectiveness and accuracy of the proposed method. Based on the numerical results, configuring a set of redundant transformers is indicated to be of the greatest significance to improve the reliability level of UHVDC transmission systems.
Thomas, J. M.; Hanagud, S.
1974-01-01
The design criteria and test options for aerospace structural reliability were investigated. A decision methodology was developed for selecting a combination of structural tests and structural design factors. The decision method involves the use of Bayesian statistics and statistical decision theory. Procedures are discussed for obtaining and updating data-based probabilistic strength distributions for aerospace structures when test information is available and for obtaining subjective distributions when data are not available. The techniques used in developing the distributions are explained.
Validity and factor structure of the bodybuilding dependence scale.
Smith, D; Hale, B
2004-04-01
To investigate the factor structure, validity, and reliability of the bodybuilding dependence scale and to investigate differences in bodybuilding dependence between men and women and competitive and non-competitive bodybuilders. Seventy two male competitive bodybuilders, 63 female competitive bodybuilders, 87 male non-competitive bodybuilders, and 63 non-competitive female bodybuilders completed the bodybuilding dependence scale (BDS), the exercise dependence questionnaire (EDQ), and the muscle dysmorphia inventory (MDI). Confirmatory factor analysis of the BDS supported a three factor model of bodybuilding dependence, consisting of social dependence, training dependence, and mastery dependence (Q = 3.16, CFI = 0.98, SRMR = 0.04). Internal reliability of all three subscales was high (Cronbach's alpha = 0.92, 0.92, and 0.93 respectively). Significant (pbodybuilders scored significantly (pbodybuilders. However, there were no significant sex differences on any of the BDS subscales (p>0.05). The three factor BDS appears to be a reliable and valid measure of bodybuilding dependence. Symptoms of bodybuilding dependence are more prevalent in competitive bodybuilders than non-competitive ones, but there are no significant sex differences in bodybuilding dependence.
The Factor Structure in Equity Options
DEFF Research Database (Denmark)
Christoffersen, Peter; Fournier, Mathieu; Jacobs, Kris
Principal component analysis of equity options on Dow-Jones firms reveals a strong factor structure. The first principal component explains 77% of the variation in the equity volatility level, 77% of the variation in the equity option skew, and 60% of the implied volatility term structure across...... equities. Furthermore, the first principal component has a 92% correlation with S&P500 index option volatility, a 64% correlation with the index option skew, and a 80% correlation with the index option term structure. We develop an equity option valuation model that captures this factor structure...
Reliability of the Structured Clinical Interview for DSM-5 Sleep Disorders Module.
Taylor, Daniel J; Wilkerson, Allison K; Pruiksma, Kristi E; Williams, Jacob M; Ruggero, Camilo J; Hale, Willie; Mintz, Jim; Organek, Katherine Marczyk; Nicholson, Karin L; Litz, Brett T; Young-McCaughan, Stacey; Dondanville, Katherine A; Borah, Elisa V; Brundige, Antoinette; Peterson, Alan L
2018-03-15
To develop and demonstrate interrater reliability for a Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) Sleep Disorders (SCISD). The SCISD was designed to be a brief, reliable, and valid interview assessment of adult sleep disorders as defined by the DSM-5. A sample of 106 postdeployment active-duty military members seeking cognitive behavioral therapy for insomnia in a randomized clinical trial were assessed with the SCISD prior to treatment to determine eligibility. Audio recordings of these interviews were double-scored for interrater reliability. The interview is 8 pages long, includes 20 to 51 questions, and takes 10 to 20 minutes to administer. Of the nine major disorders included in the SCISD, six had prevalence rates high enough (ie, n ≥ 5) to include in analyses. Cohen kappa coefficient (κ) was used to assess interrater reliability for insomnia, hypersomnolence, obstructive sleep apnea hypopnea (OSAH), circadian rhythm sleep-wake, nightmare, and restless legs syndrome disorders. There was excellent interrater reliability for insomnia (1.0) and restless legs syndrome (0.83); very good reliability for nightmare disorder (0.78) and OSAH (0.73); and good reliability for hypersomnolence (0.50) and circadian rhythm sleep-wake disorders (0.50). The SCISD is a brief, structured clinical interview that is easy for clinicians to learn and use. The SCISD showed moderate to excellent interrater reliability for six of the major sleep disorders in the DSM-5 among active duty military seeking cognitive behavioral therapy for insomnia in a randomized clinical trial. Replication and extension studies are needed. Registry: ClinicalTrials.gov; Title: Comparing Internet and In-Person Brief Cognitive Behavioral Therapy of Insomnia; Identifier: NCT01549899; URL: https://clinicaltrials.gov/ct2/show/NCT01549899. © 2018 American Academy of Sleep Medicine.
Li, Haibin; He, Yun; Nie, Xiaobo
2018-01-01
Structural reliability analysis under uncertainty is paid wide attention by engineers and scholars due to reflecting the structural characteristics and the bearing actual situation. The direct integration method, started from the definition of reliability theory, is easy to be understood, but there are still mathematics difficulties in the calculation of multiple integrals. Therefore, a dual neural network method is proposed for calculating multiple integrals in this paper. Dual neural network consists of two neural networks. The neural network A is used to learn the integrand function, and the neural network B is used to simulate the original function. According to the derivative relationships between the network output and the network input, the neural network B is derived from the neural network A. On this basis, the performance function of normalization is employed in the proposed method to overcome the difficulty of multiple integrations and to improve the accuracy for reliability calculations. The comparisons between the proposed method and Monte Carlo simulation method, Hasofer-Lind method, the mean value first-order second moment method have demonstrated that the proposed method is an efficient and accurate reliability method for structural reliability problems.
Bogachkov, I. V.; Lutchenko, S. S.
2018-05-01
The article deals with the method for the assessment of the fiber optic communication lines (FOCL) reliability taking into account the effect of the optical fiber tension, the temperature influence and the built-in diagnostic equipment errors of the first kind. The reliability is assessed in terms of the availability factor using the theory of Markov chains and probabilistic mathematical modeling. To obtain a mathematical model, the following steps are performed: the FOCL state is defined and validated; the state graph and system transitions are described; the system transition of states that occur at a certain point is specified; the real and the observed time of system presence in the considered states are identified. According to the permissible value of the availability factor, it is possible to determine the limiting frequency of FOCL maintenance.
Directory of Open Access Journals (Sweden)
Marco Aurelio Lumertz Saffi
2013-10-01
Full Text Available Using a sample of patients with coronary artery disease, this methodological study aimed to conduct a cross-cultural adaptation and validation of a questionnaire on knowledge of cardiovascular risk factors (Q-FARCS, lifestyle changes, and treatment adherence for use in Brazil. The questionnaire has three scales: general knowledge of risk factors (RFs; specific knowledge of these RFs; and lifestyle changes achieved. Cross-cultural adaptation included translation, synthesis, back-translation, expert committee review, and pretesting. Face and content validity, reliability, and construct validity were measured. Cronbach’s alpha for the total sample (n = 240 was 0.75. Assessment of psychometric properties revealed adequate face and content validity, and the construct revealed seven components. It was concluded that the Brazilian version of Q-FARCS had adequate reliability and validity for the assessment of knowledge of cardiovascular RFs.
Holographic analysis of diffraction structure factors
International Nuclear Information System (INIS)
Marchesini, S.; Bucher, J.J.; Shuh, D.K.; Fabris, L.; Press, M.J.; West, M.W.; Hussain, Z.; Mannella, N.; Fadley, C.S.; Van Hove, M.A.; Stolte, W.C.
2002-01-01
We combine the theory of inside-source/inside-detector x-ray fluorescence holography and Kossel lines/ x ray standing waves in kinematic approximation to directly obtain the phases of the diffraction structure factors. The influence of Kossel lines and standing waves on holography is also discussed. We obtain partial phase determination from experimental data obtaining the sign of the real part of the structure factor for several reciprocal lattice vectors of a vanadium crystal
Effect of soil–structure interaction on the reliability of reinforced concrete bridges
Directory of Open Access Journals (Sweden)
Kamel Bezih
2015-09-01
Full Text Available In the design of reinforced concrete (RC bridges, the random and nonlinear behavior of soil may lead to insufficient reliability levels. For this reason, it is necessary to take into account the variability of soil properties which can significantly affect the bridge behavior regarding ultimate and serviceability limit states. This study investigates the failure probability for existing reinforced concrete bridges due to the effects of interaction between the soil and the structure. In this paper, a coupled reliability–mechanical approach is developed to study the effect of soil–structure interaction for RC bridges. The modeling of this interaction is incorporated into the mechanical model of RC continuous beams, by considering nonlinear elastic soil stiffness. The reliability analysis highlights the large importance of soil–structure interaction and shows that the structural safety is highly sensitive to the variability of soil properties, especially when the nonlinear behavior of soil is considered.
DEFF Research Database (Denmark)
Hovgaard, Mads Knude; Hansen, Jannick Balleby; Brincker, Rune
2013-01-01
A scenario- and vibration based structural damage detection method is demonstrated though simulation. The method is Finite Element (FE) based. The value of the monitoring is calculated using structural reliability theory. A high cycle fatigue crack propagation model is assumed as the damage mecha......- and without monitoring. Monte Carlo Sampling (MCS) is used to estimate the probabilities and the tower of an onshore NREL 5MW wind turbine is given as a calculation case......A scenario- and vibration based structural damage detection method is demonstrated though simulation. The method is Finite Element (FE) based. The value of the monitoring is calculated using structural reliability theory. A high cycle fatigue crack propagation model is assumed as the damage...
Methodology for performing RF reliability experiments on a generic test structure
Sasse, G.T.; de Vries, Rein J.; Schmitz, Jurriaan
2007-01-01
This paper discusses a new technique developed for generating well defined RF large voltage swing signals for on wafer experiments. This technique can be employed for performing a broad range of different RF reliability experiments on one generic test structure. The frequency dependence of a
International Nuclear Information System (INIS)
Chevalier, M.J.; Smith, D.J.; Dean, D.W.
2012-01-01
Deterministic assessments are used to assess the integrity of structural systems operating at high temperature by providing a lower bound lifetime prediction, requiring considerable engineering judgement. However such a result may not satisfy the structural integrity assessment purpose if the results are overly conservative or conversely plant observations (such as failures) could undermine the assessment result if observed before the lower bound lifetime. This paper develops a reliability methodology for high temperature assessments and illustrates the impact and importance of managing the uncertainties within such an analysis. This is done by separating uncertainties into three classifications; aleatory uncertainty, quantifiable epistemic uncertainty and unquantifiable epistemic uncertainty. The result is a reliability model that can predict the behaviour of a structural system based upon plant observations, including failure and survival data. This can be used to reduce the over reliance upon engineering judgement which is prevalent in deterministic assessments. Highlights: ► Deterministic assessments are shown to be heavily reliant upon engineering judgment. ► Based upon the R5 procedure, a reliability model for a structural system is developed. ► Variables must be classified as either aleatory or epistemic to model their impact on reliability. ► Operation experience is then used to reduce reliance upon engineering judgment. ► This results in a model which can predict system behaviour and learn from operational experience.
DEFF Research Database (Denmark)
Ingwersen, Kim Gordon; Hjarbæk, John; Eshøj, Henrik
2016-01-01
Aim To evaluate the inter-rater reliability of measuring structural changes in the tendon of patients, clinically diagnosed with supraspinatus tendinopathy (cases) and healthy participants (controls), on ultrasound (US) images captured by standardised procedures. Methods A total of 40 participant...
Monte Carlo simulation - a powerful tool to support experimental activities in structure reliability
International Nuclear Information System (INIS)
Yuritzinn, T.; Chapuliot, S.; Eid, M.; Masson, R.; Dahl, A.; Moinereau, D.
2003-01-01
Monte-Carlo Simulation (MCS) can have different uses in supporting structure reliability investigations and assessments. In this paper we focus our interest on the use of MCS as a numerical tool to support the fitting of the experimental data related to toughness experiments. (authors)
Woodburn, Jim; Sutcliffe, Nick
1996-01-01
The Objective Structured Clinical Examination (OSCE), initially developed for undergraduate medical education, has been adapted for assessment of clinical skills in podiatry students. A 12-month pilot study found the test had relatively low levels of reliability, high construct and criterion validity, and good stability of performance over time.…
RESEARCH OF SYNERGETIC RELIABILITY OF PEARLITE-REDUCED STRUCTURAL STEEL 09G2FB
Directory of Open Access Journals (Sweden)
Gustov Yuriy Ivanovich
2012-10-01
Full Text Available The primary objective of the research is the synergetic reliability of perlite-reduced structural steel 09G2FB exposed to various thermal and mechanical treatments. In the aftermath of the above exposure, the steel in question has proved to assume a set of strength-related and plastic mechanical properties (σσδ and ψ.
Kingston, Greer B.; Rajabali Nejad, Mohammadreza; Gouldby, Ben P.; van Gelder, Pieter H.A.J.M.
2011-01-01
With the continual rise of sea levels and deterioration of flood defence structures over time, it is no longer appropriate to define a design level of flood protection, but rather, it is necessary to estimate the reliability of flood defences under varying and uncertain conditions. For complex
The Reliability and Structure of the Classroom Assessment Scoring System in German Pre-Schools
Stuck, Andrea; Kammermeyer, Gisela; Roux, Susanna
2016-01-01
This study examined the reliability and structure of the Classroom Assessment Scoring System (CLASS; Pianta, R. C., K. M. La Paro, and B. K. Hamre. 2008. "Classroom Assessment Scoring System. Manual Pre-K." Baltimore, MD: Brookes) and the quality of interactional processes in a German pre-school setting, drawing on a sample of 390…
International Nuclear Information System (INIS)
2005-06-01
As the 35th domestic symposium of Atomic Energy Research Committee, the Japan Welding Engineering Society, the symposium was held titled as Applications of structural reliability/risk assessment methods to nuclear energy'. Six speakers gave lectures titled as 'Structural reliability and risk assessment methods', 'Risk-informed regulation of US nuclear energy and role of probabilistic risk assessment', 'Reliability and risk assessment methods in chemical plants', 'Practical structural design methods based on reliability in architectural and civil areas', 'Maintenance activities based on reliability in thermal power plants' and 'LWR maintenance strategies based on Probabilistic Fracture Mechanics'. (T. Tanaka)
Notes on human factors problems in process plant reliability and safety prediction
International Nuclear Information System (INIS)
Rasmussen, J.; Taylor, J.R.
1976-09-01
The basis for plant operator reliability evaluation is described. Principles for plant design, necessary to permit reliability evaluation, are outlined. Five approaches to the plant operator reliability problem are described. Case stories, illustrating operator reliability problems, are given. (author)
Karri, Naveen K.; Mo, Changki
2018-06-01
Structural reliability of thermoelectric generation (TEG) systems still remains an issue, especially for applications such as large-scale industrial or automobile exhaust heat recovery, in which TEG systems are subject to dynamic loads and thermal cycling. Traditional thermoelectric (TE) system design and optimization techniques, focused on performance alone, could result in designs that may fail during operation as the geometric requirements for optimal performance (especially the power) are often in conflict with the requirements for mechanical reliability. This study focused on reducing the thermomechanical stresses in a TEG system without compromising the optimized system performance. Finite element simulations were carried out to study the effect of TE element (leg) geometry such as leg length and cross-sectional shape under constrained material volume requirements. Results indicated that the element length has a major influence on the element stresses whereas regular cross-sectional shapes have minor influence. The impact of TE element stresses on the mechanical reliability is evaluated using brittle material failure theory based on Weibull analysis. An alternate couple configuration that relies on the industry practice of redundant element design is investigated. Results showed that the alternate configuration considerably reduced the TE element and metallization stresses, thereby enhancing the structural reliability, with little trade-off in the optimized performance. The proposed alternate configuration could serve as a potential design modification for improving the reliability of systems optimized for thermoelectric performance.
Carvalho, Hudson W de; Andreoli, Sérgio B; Lara, Diogo R; Patrick, Christopher J; Quintana, Maria Inês; Bressan, Rodrigo A; Melo, Marcelo F de; Mari, Jair de J; Jorge, Miguel R
2013-01-01
Positive and negative affect are the two psychobiological-dispositional dimensions reflecting proneness to positive and negative activation that influence the extent to which individuals experience life events as joyful or as distressful. The Positive and Negative Affect Schedule (PANAS) is a structured questionnaire that provides independent indexes of positive and negative affect. This study aimed to validate a Brazilian interview-version of the PANAS by means of factor and internal consistency analysis. A representative community sample of 3,728 individuals residing in the cities of São Paulo and Rio de Janeiro, Brazil, voluntarily completed the PANAS. Exploratory structural equation model analysis was based on maximum likelihood estimation and reliability was calculated via Cronbach's alpha coefficient. Our results provide support for the hypothesis that the PANAS reliably measures two distinct dimensions of positive and negative affect. The structure and reliability of the Brazilian version of the PANAS are consistent with those of its original version. Taken together, these results attest the validity of the Brazilian adaptation of the instrument.
An Intelligent Method for Structural Reliability Analysis Based on Response Surface
Institute of Scientific and Technical Information of China (English)
桂劲松; 刘红; 康海贵
2004-01-01
As water depth increases, the structural safety and reliability of a system become more and more important and challenging. Therefore, the structural reliability method must be applied in ocean engineering design such as offshore platform design. If the performance function is known in structural reliability analysis, the first-order second-moment method is often used. If the performance function could not be definitely expressed, the response surface method is always used because it has a very clear train of thought and simple programming. However, the traditional response surface method fits the response surface of quadratic polynomials where the problem of accuracy could not be solved, because the true limit state surface can be fitted well only in the area near the checking point. In this paper, an intelligent computing method based on the whole response surface is proposed, which can be used for the situation where the performance function could not be definitely expressed in structural reliability analysis. In this method, a response surface of the fuzzy neural network for the whole area should be constructed first, and then the structural reliability can be calculated by the genetic algorithm. In the proposed method, all the sample points for the training network come from the whole area, so the true limit state surface in the whole area can be fitted. Through calculational examples and comparative analysis, it can be known that the proposed method is much better than the traditional response surface method of quadratic polynomials, because, the amount of calculation of finite element analysis is largely reduced, the accuracy of calculation is improved,and the true limit state surface can be fitted very well in the whole area. So, the method proposed in this paper is suitable for engineering application.
The performance shaping factors influence analysis on the human reliability for NPP operation
International Nuclear Information System (INIS)
Farcasiu, M.; Nitoi, M.; Apostol, M.; Florescu, G.
2008-01-01
The Human Reliability Analysis (HRA) is an important step in Probabilistic Safety Assessment (PSA) studies and offers an advisability for concrete improvement of the man - machine - organization interfaces, reliability and safety. The goals of this analysis are to obtain sufficient details in order to understand and document all-important factors that affect human performance. The purpose of this paper is to estimate the human errors probabilities in view of the negative or positive effect of the human performance shaping factors (PSFs) for the mitigation of the initiating events which could occur in Nuclear Power Plant (NPP). Using THERP and SPAR-H methods, an analysis model of PSFs influence on the human reliability is performed. This model is applied to more important activities, that are necessary to mitigate 'one steam generator tube failure' event at Cernavoda NPP. The results are joint human error probabilities (JHEP) values estimated for the following situations: without regarding to PSFs influence; with PSFs in specific conditions; with PSFs which could have only positive influence and with PSFs which could have only negative influence. In addition, PSFs with negative influence were identified and using the DOE method, the necessary activities for changing negative influence were assigned. (authors)
Directory of Open Access Journals (Sweden)
McGinn Aileen P
2005-06-01
Full Text Available Abstract Background Despite the documented benefits of physical activity, many adults do not obtain the recommended amounts. Barriers to physical activity occur at multiple levels, including at the individual, interpersonal, and environmental levels. Only until more recently has there been a concerted focus on how the physical environment might affect physical activity behavior. With this new area of study, self-report measures should be psychometrically tested before use in research studies. Therefore the objective of this study was to document the test-retest reliability of a questionnaire designed to assess physical environmental factors that might be associated with physical activity in a diverse adult population. Methods Test and retest surveys were conducted over the telephone with 106 African American and White women and men living in either Forsyth County, North Carolina or Jackson, Mississippi. Reliability of self-reported environmental factors across four domains (e.g., access to facilities and destinations, functionality and safety, aesthetics, natural environment was determined using intraclass correlation coefficients (ICC overall and separately by gender and race. Results Generally items displayed moderate and sometimes substantial reliability (ICC between 0.4 to 0.8, with a few differences by gender or race, across each of the domains. Conclusion This study provides some psychometric evidence for the use of many of these questions in studies examining the effect of self-reported physical environmental measures on physical activity behaviors, among African American and White women and men.
Structural reliability analysis under evidence theory using the active learning kriging model
Yang, Xufeng; Liu, Yongshou; Ma, Panke
2017-11-01
Structural reliability analysis under evidence theory is investigated. It is rigorously proved that a surrogate model providing only correct sign prediction of the performance function can meet the accuracy requirement of evidence-theory-based reliability analysis. Accordingly, a method based on the active learning kriging model which only correctly predicts the sign of the performance function is proposed. Interval Monte Carlo simulation and a modified optimization method based on Karush-Kuhn-Tucker conditions are introduced to make the method more efficient in estimating the bounds of failure probability based on the kriging model. Four examples are investigated to demonstrate the efficiency and accuracy of the proposed method.
International Nuclear Information System (INIS)
Kim, Ar Ryum; Jang, Inseok Jang; Seong, Poong Hyun; Park, Jinkyun; Kim, Jong Hyun
2015-01-01
The purpose of HRA implementation is 1) to achieve the human factor engineering (HFE) design goal of providing operator interfaces that will minimize personnel errors and 2) to conduct an integrated activity to support probabilistic risk assessment (PRA). For these purposes, various HRA methods have been developed such as technique for human error rate prediction (THERP), simplified plant analysis risk human reliability assessment (SPAR-H), cognitive reliability and error analysis method (CREAM) and so on. In performing HRA, such conditions that influence human performances have been represented via several context factors called performance shaping factors (PSFs). PSFs are aspects of the human's individual characteristics, environment, organization, or task that specifically decrements or improves human performance, thus respectively increasing or decreasing the likelihood of human errors. Most HRA methods evaluate the weightings of PSFs by expert judgment and explicit guidance for evaluating the weighting is not provided. It has been widely known that the performance of the human operator is one of the critical factors to determine the safe operation of NPPs. HRA methods have been developed to identify the possibility and mechanism of human errors. In performing HRA methods, the effect of PSFs which may increase or decrease human error should be investigated. However, the effect of PSFs were estimated by expert judgment so far. Accordingly, in order to estimate the effect of PSFs objectively, the quantitative framework to estimate PSFs by using PSF profiles is introduced in this paper
Park, Jung-Keun; Boyer, Jon; Tessler, Jamie; Casey, Jeffrey; Schemm, Linda; Gore, Rebecca; Punnett, Laura
2009-07-01
This study examined the inter-rater reliability of expert observations of ergonomic risk factors by four analysts. Ten jobs were observed at a hospital using a newly expanded version of the PATH method (Buchholz et al. 1996), to which selected upper extremity exposures had been added. Two of the four raters simultaneously observed each worker onsite for a total of 443 observation pairs containing 18 categorical exposure items each. For most exposure items, kappa coefficients were 0.4 or higher. For some items, agreement was higher both for the jobs with less rapid hand activity and for the analysts with a higher level of ergonomic job analysis experience. These upper extremity exposures could be characterised reliably with real-time observation, given adequate experience and training of the observers. The revised version of PATH is applicable to the analysis of jobs where upper extremity musculoskeletal strain is of concern.
Reliability Analysis and Test Planning using CAPO-Test for Existing Structures
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Engelund, S.; Faber, Michael Havbro
2000-01-01
Evaluation of the reliability of existing concrete structures often requires that the compressive strength of the concrete is estimated on the basis of tests performed with concrete samples from the structure considered. In this paper the CAPO-test method is considered. The different sources...... of uncertainty related to this method are described. It is shown how the uncertainty in the transformation from the CAPO-test results to estimates of the concrete strength can be modeled. Further, the statistical uncertainty is modeled using Bayesian statistics. Finally, it is shown how reliability-based optimal...... planning of CAPO-tests can be performed taking into account the expected costs due to the CAPO-tests and possible repair or failure of the structure considered. An illustrative example is presented where the CAPO-test is compared with conventional concrete cylinder compression tests performed on cores...
Reliability analysis based on a novel density estimation method for structures with correlations
Directory of Open Access Journals (Sweden)
Baoyu LI
2017-06-01
Full Text Available Estimating the Probability Density Function (PDF of the performance function is a direct way for structural reliability analysis, and the failure probability can be easily obtained by integration in the failure domain. However, efficiently estimating the PDF is still an urgent problem to be solved. The existing fractional moment based maximum entropy has provided a very advanced method for the PDF estimation, whereas the main shortcoming is that it limits the application of the reliability analysis method only to structures with independent inputs. While in fact, structures with correlated inputs always exist in engineering, thus this paper improves the maximum entropy method, and applies the Unscented Transformation (UT technique to compute the fractional moments of the performance function for structures with correlations, which is a very efficient moment estimation method for models with any inputs. The proposed method can precisely estimate the probability distributions of performance functions for structures with correlations. Besides, the number of function evaluations of the proposed method in reliability analysis, which is determined by UT, is really small. Several examples are employed to illustrate the accuracy and advantages of the proposed method.
International Nuclear Information System (INIS)
Procaccia, H.; Morilhat, P.; Carle, R.; Menjon, G.
1996-01-01
The management of the service life of mechanical materials implies an evaluation of their risk of failure during their use. To evaluate this risk the following methods are used: the classical frequency statistics applied to experience feedback data concerning failures noticed during operation of active parts (pumps, valves, exchangers, circuit breakers etc..); the Bayesian approach in the case of scarce statistical data and when experts are needed to compensate the lack of information; the structures reliability approach when no data are available and when a theoretical model of degradation must be used, in particular for passive structures (pressure vessels, pipes, tanks, etc..). The aim of this book is to describe the principles and applications of this third approach to industrial installations. Chapter 1 recalls the historical aspects of the probabilistic approach to the reliability of structures and the existing codes. Chapter 2 presents the level 1 deterministic method applied so far for the conceiving of passive structures. The Cornell reliability index, already used in civil engineering codes, is defined in chapter 3. The Hasofer and Lind reliability index, a generalization of the Cornell index, is defined in chapter 4. Chapter 5 concerns the application of probabilistic approaches to optimization studies with the introduction of the economical variables linked to the risk and the possible actions to limit this risk (in-service inspection, maintenance, repairing etc..). Chapters 6 and 7 describe the Monte Carlo simulation and approximation methods for failure probabilistic calculations, and recall the fracture mechanics basis and the models of load and degradation of industrial installations. Some applications are given in chapter 9 with the cases of the safety margins quantization of a fissured pipe and the optimizing of the in-service inspection policy of a steam generator. Chapter 10 raises the problem of the coupling between mechanical and reliability
International Nuclear Information System (INIS)
Wilpert, B.; Maimer, H.; Loroff, C.
2000-01-01
The project's objectives are the evaluation of the reliability concerning the identification of Human Factors as contributing factors by a computer supported event analysis (CEA). CEA is a computer version of SOL (Safety through Organizational Learning). Parts of the first step were interviews with experts from the nuclear power industry and the evaluation of existing computer supported event analysis methods. This information was combined to a requirement profile for the CEA software. The next step contained the implementation of the software in an iterative process of evaluation. The completion of this project was the testing of the CEA software. As a result the testing demonstrated that it is possible to identify contributing factors with CEA validly. In addition, CEA received a very positive feedback from the experts. (orig.) [de
Edwards, L.; Santisteban, J. R.
The determination of accurate reliable residual stresses is critical to many fields of structural integrity. Neutron stress measurement is a non-destructive technique that uniquely provides insights into stress fields deep within engineering components and structures. As such, it has become an increasingly important tool within engineering, leading to improved manufacturing processes to reduce stress and distortion as well as to the definition of more precise lifing procedures. This paper describes the likely impact of the next generation of dedicated engineering stress diffractometers currently being constructed and the utility of the technique using examples of residual stresses both beneficial and detrimental to structural integrity.
Human and organisational factors in the reliability of non-destructive testing (NOT)
International Nuclear Information System (INIS)
Norros, L.
1998-01-01
Non-destructive testing used in in-service inspections can be seen as a complicated activity system including three mutually related sub-activities: (1) definition of inspection programs and necessary resources, (2) carrying out diagnostic inspections, and (3) interpretation of the results from the view of plant safety and corrective measures. Various studies to investigate and measure the NDT performance have produced disappointing result. No clear correlations between single human factors and performance have been identified even though general agreement exists concerning the significance of human factors to the reliability of testing. Another incentive for our studies has been to test and evaluate the applicability of the international results in the Finnish circumstances. Three successive studies have thus been carried out on the human and organisational factors in non-destructive testing. (author)
Reliability of multi-model and structurally different single-model ensembles
Energy Technology Data Exchange (ETDEWEB)
Yokohata, Tokuta [National Institute for Environmental Studies, Center for Global Environmental Research, Tsukuba, Ibaraki (Japan); Annan, James D.; Hargreaves, Julia C. [Japan Agency for Marine-Earth Science and Technology, Research Institute for Global Change, Yokohama, Kanagawa (Japan); Collins, Matthew [University of Exeter, College of Engineering, Mathematics and Physical Sciences, Exeter (United Kingdom); Jackson, Charles S.; Tobis, Michael [The University of Texas at Austin, Institute of Geophysics, 10100 Burnet Rd., ROC-196, Mail Code R2200, Austin, TX (United States); Webb, Mark J. [Met Office Hadley Centre, Exeter (United Kingdom)
2012-08-15
The performance of several state-of-the-art climate model ensembles, including two multi-model ensembles (MMEs) and four structurally different (perturbed parameter) single model ensembles (SMEs), are investigated for the first time using the rank histogram approach. In this method, the reliability of a model ensemble is evaluated from the point of view of whether the observations can be regarded as being sampled from the ensemble. Our analysis reveals that, in the MMEs, the climate variables we investigated are broadly reliable on the global scale, with a tendency towards overdispersion. On the other hand, in the SMEs, the reliability differs depending on the ensemble and variable field considered. In general, the mean state and historical trend of surface air temperature, and mean state of precipitation are reliable in the SMEs. However, variables such as sea level pressure or top-of-atmosphere clear-sky shortwave radiation do not cover a sufficiently wide range in some. It is not possible to assess whether this is a fundamental feature of SMEs generated with particular model, or a consequence of the algorithm used to select and perturb the values of the parameters. As under-dispersion is a potentially more serious issue when using ensembles to make projections, we recommend the application of rank histograms to assess reliability when designing and running perturbed physics SMEs. (orig.)
Directory of Open Access Journals (Sweden)
Ebrahim Khodadady
2013-06-01
The 133-item Emotional Quotient Inventory (EQ-i designed by Bar-On (1997 and translated by Dehshiry (2003 was revised and modified by removing the response validity items, changing reverse indicators into positively worded statements and revising the remaining 117 Persian indicators on the basis of schema theory. It was administered to 669 instructors most of whom were teaching English as a foreign language (EFL in national branches of Iran Language Institute in 15 cities. The application of the Principal Axis Factoring to the data and rotating the extracted factors via Varimax with Kaiser Normalization yielded 15 latent variables (LVs called Humanistic, Self-Satisfying, Self-Confident, Self-Aware, Self-Controlled, Research-Oriented, Content, Sociable, Empathetic, Tolerant, Flexible, Realistic, Independent, Emotional and Happy in this study. Not only did the modified Persian EQ-I proved to be more reliable than its original version, but also its thirteen LVs reached very high and acceptable levels of reliability. With the exception of the last, all the LVs also correlated significantly with each other and thus established the EI as a multifactorial construct whose constituting LVs are closely related to each other. The findings question correlating the so-called competences of EI and offer employing the factorially valid LVs as the best factors to explore the relationship between EI and variables involved in teaching and learning EFL.
Validity and Reliability of 2 Goniometric Mobile Apps: Device, Application, and Examiner Factors.
Wellmon, Robert H; Gulick, Dawn T; Paterson, Mark L; Gulick, Colleen N
2016-12-01
Smartphones are being used in a variety of practice settings to measure joint range of motion (ROM). A number of factors can affect the validity of the measurements generated. However, there are no studies examining smartphone-based goniometer applications focusing on measurement variability and error arising from the electromechanical properties of the device being used. To examine the concurrent validity and interrater reliability of 2 goniometric mobile applications (Goniometer Records, Goniometer Pro), an inclinometer, and a universal goniometer (UG). Nonexperimental, descriptive validation study. University laboratory. 3 physical therapists having an average of 25 y of experience. Three standardized angles (acute, right, obtuse) were constructed to replicate the movement of a hinge joint in the human body. Angular changes were measured and compared across 3 raters who used 3 different devices (UG, inclinometer, and 2 goniometric apps installed on 3 different smartphones: Apple iPhone 5, LG Android, and Samsung SIII Android). Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to examine interrater reliability and concurrent validity. Interrater reliability for each of the smartphone apps, inclinometer and UG were excellent (ICC = .995-1.000). Concurrent validity was also good (ICC = .998-.999). Based on the Bland-Altman plots, the means of the differences between the devices were low (range = -0.4° to 1.2°). This study identifies the error inherent in measurement that is independent of patient factors and due to the smartphone, the installed apps, and examiner skill. Less than 2° of measurement variability was attributable to those factors alone. The data suggest that 3 smartphones with the 2 installed apps are a viable substitute for using a UG or an inclinometer when measuring angular changes that typically occur when examining ROM and demonstrate the capacity of multiple examiners to accurately use smartphone-based goniometers.
Effects of Common Structural Rules on hull-girder reliability of an Aframax oil tanker
International Nuclear Information System (INIS)
Parunov, Josko; Guedes Soares, C.
2008-01-01
This paper aims at quantifying the changes in notional reliability levels that result from redesigning an existing Aframax tanker to comply with the Common Structural Rules (CSR) for double-hull oil tankers. The probability of structural failure is calculated using the first-order reliability method. The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out in accordance with the International Association of Classification Societies (IACS)-recommended procedure, while transfer functions are calculated using the sink-source 3D linear method. The still-water loads are defined on the basis of a statistical analysis of loading conditions from the loading manual. The ultimate collapse bending moment of the midship cross section, which is used as the basis for the reliability formulation, is evaluated by progressive collapse analysis and by a single-step procedure according to CSR. The reliability assessment is performed for 'as-built' and 'corroded' states of the existing ship and a reinforced ship complying with CSR. It is shown that the hull-girder failure probability of an Aframax tanker is reduced several times due to the reinforcements according to CSR. Sensitivity analysis and a parametric study are performed to investigate the variability of results with the change of parameters of pertinent random variables within their plausible ranges. Finally, differences between load combination approaches by Ferry-Borges and Castanheta method and Turkstra's rule are investigated
Directory of Open Access Journals (Sweden)
Dookie Kim
Full Text Available This paper presents a probabilistic capacity spectrum strategy for the reliability analysis of a bridge pile shaft, accounting for uncertainties in design factors in the analysis and the soil-structure interaction (SSI. Monte Carlo simulation method (MCS is adopted to determine the probabilities of failure by comparing the responses with defined limit states. The analysis considers the soil structure interaction together with the probabilistic application of the capacity spectrum method for different types of limit states. A cast-in-drilledhole (CIDH extended reinforced concrete pile shaft of a bridge is analysed using the proposed strategy. The results of the analysis show that the SSI can lead to increase or decrease of the structure's probability of failure depending on the definition of the limit states.
The evaluation of equipment and Instrumentation Reliability Factors on Power Reactor
International Nuclear Information System (INIS)
Supriatna, Piping; Karlina, Itjeu; Widagdo, Suharyo; Santosa, Kussigit; Darlis; Sudiyono, Bambang; Yuniyanta, Sasongko; Sudarmin
1999-01-01
Equipment and instrumentation reliability on type power reactor control room was determined by its pattern and design. the principle of ergonomy applied on equipment and instrumentation layout in this ABWR type reactor are geometric pattern appropriate with economic body motion, average anthropometry data of operator especially operator hand-reach, range of vision, angle of vision, lighting, color arrangement and harmony as will as operator case in operating the equipment system. Limitation criteria of the parameter mentioned above are based on EPRI NP-3659, NURG 0700, and NUREG/CR-3331 documents. Besides that, the (working) physical environment parameter factor of the control room must be designed in order to fulfil the standard criteria of ergonomic condition based on NUREG-0800. The reliability evaluation of equipment and instrumentation system also occurs observed from man machine interaction side which happen between operator and equipment and instrumentation in the ABWR type power reactor control room. From the MMI analysis can be known the working failure possibility which is caused by the operator. The evaluation result of equipment and instrumentation reliability on ABWR type power reactor control room showed that the design of this ABWR control room is good and fulfils the ergonomy standard criteria have been determined
Factor structure and concurrent validity of the world assumptions scale.
Elklit, Ask; Shevlin, Mark; Solomon, Zahava; Dekel, Rachel
2007-06-01
The factor structure of the World Assumptions Scale (WAS) was assessed by means of confirmatory factor analysis. The sample was comprised of 1,710 participants who had been exposed to trauma that resulted in whiplash. Four alternative models were specified and estimated using LISREL 8.72. A correlated 8-factor solution was the best explanation of the sample data. The estimates of reliability of eight subscales of the WAS ranged from .48 to .82. Scores from five subscales correlated significantly with trauma severity as measured by the Harvard Trauma Questionnaire, although the magnitude of the correlations was low to modest, ranging from .08 to -.43. It is suggested that the WAS has adequate psychometric properties for use in both clinical and research settings.
On R factors for dynamic structure crystallography
DEFF Research Database (Denmark)
Coppens, Philip; Kaminski, Radoslaw; Schmøkel, Mette Stokkebro
2010-01-01
In studies of dynamic changes in crystals in which induced metastable species may have lifetimes of microseconds or less, refinements are most sensitive if based on the changes induced in the measured intensities. Agreement factors appropriate for such refinements, based on the ratios of the inte...... of the intensities before and after the external perturbation is applied, are discussed and compared with R factors commonly applied in static structure crystallography....
Structural studies on leukaemia inhibitory factor
Energy Technology Data Exchange (ETDEWEB)
Norton, R.S.; Maurer, T.; Smith, D.K. [Biomolecular Research Institute, Parville (Australia); Nicola, N.A. [Institute of Medical Research, Melbourne (Australia)
1994-12-01
Leukaemia Inhibitory Factor (LIF) is a pleiotropic cytokine that acts on a wide range of target cells, including mega-karyocytes, osteoblasts, hepatocytes, adipocytes, neurons, embryonic stem cells, and primordial germ cells. Many of its activities are shared with other cytokines, particularly interleukin-6, oncostatin-M, ciliary neurotrophic factor, and granulocyte colony-stimulating factor (G-CSF). Although secreted in vivo as a glycoprotein, nonglycosylated recombinant protein expressed in E. coli is fully active and has been used in our nuclear magnetic resonance (NMR) studies of the three-dimensional structure and structure-function relationships of LIF. With 180 amino acids and a molecular mass of about 20 kDa, OF is too large for direct structure determination by two-dimensional and three-dimensional {sup 1}HNMR. It is necessary to label the protein with the stable isotopes {sup 15}N and {sup 13}C and employ heteronuclear three-dimensional NMR in order to resolve and interpret the spectral information required for three-dimensional structure determination. This work has been undertaken with both human LIF and a mouse-human chimaera that binds to the human LIF receptor with the same affinity as the human protein and yet expresses in E. coli at much higher levels. Sequence-specific resonance assignments and secondary structure elements for these proteins will be presented and progress towards determination of their three-dimensional structures described.
International Nuclear Information System (INIS)
Witt, F.J.
1980-01-01
Primary pressure systems of nuclear power plants are built to exacting codes and standards with provisions for inservice inspection and repair if necessary. Analyses and experiments have demonstrated by deterministic means that very large margins exist on safety impacting failures under normal operating and upset conditions. Probabilistic structural reliability analyses provide additional support that failures of significance are very, very remote. They may range in degree of sophistication from very simple calculations to very complex computer analyses involving highly developed mathematical techniques. The end result however should be consistent with the desired usage. In this paper a probabilistic structural reliability analysis is performed as a supplement to in-depth deterministic evaluations with the primary objective to demonstrate an acceptably low probability of failure for the conditions considered. (author)
Finite Element Reliability Analysis of Chloride Ingress into Reinforced Concrete Structures
DEFF Research Database (Denmark)
Frier, Christian; Sørensen, John Dalsgaard
2007-01-01
For many reinforced concrete structures corrosion of the reinforcement is an important problem since it can result in maintenance and repair actions. Further, a reduction of the load-bearing capacity can occur. In the present paper the Finite Element Reliability Method (FERM) is employed for obta......For many reinforced concrete structures corrosion of the reinforcement is an important problem since it can result in maintenance and repair actions. Further, a reduction of the load-bearing capacity can occur. In the present paper the Finite Element Reliability Method (FERM) is employed...... concentration and reinforcement cover depth are modelled by stochastic fields, which are discretized using the Expansion Optimum Linear Estimation (EOLE) approach. The response gradients needed for FORM analysis are derived analytically using the Direct Differentiation Method (DDM). As an example, a bridge pier...... in a marine environment is considered and the results are given in terms of distributions of time for initiation of corrosion....
International Nuclear Information System (INIS)
Maaroufi, S; Parrain, F; Lefeuvre, E; Boutaud, B; Molin, R Dal
2015-01-01
In this paper we propose an approach to study the reliability of piezoelectric structures and more precisely energy harvesting micro-devices dedicated to autonomous active medical implants (new generation pacemakers). The structure under test is designed as a bimorph piezoelectric cantilever with a seismic mass at its tip. Good understanding of material aging and mechanical failure is critical for this kind of system. To study the reliability and durability of the piezoelectric part we propose to establish a new accelerated methodology and an associated test bench where the environment and stimuli can be precisely controlled over a wide period of time. This will allow the identification of potential failure modes and the study of their impacts by the way of direct mechanical investigation based on stiffness and blocking force measurements performed periodically. (paper)
Maaroufi, S.; Parrain, F.; Lefeuvre, E.; Boutaud, B.; Dal Molin, R.
2015-12-01
In this paper we propose an approach to study the reliability of piezoelectric structures and more precisely energy harvesting micro-devices dedicated to autonomous active medical implants (new generation pacemakers). The structure under test is designed as a bimorph piezoelectric cantilever with a seismic mass at its tip. Good understanding of material aging and mechanical failure is critical for this kind of system. To study the reliability and durability of the piezoelectric part we propose to establish a new accelerated methodology and an associated test bench where the environment and stimuli can be precisely controlled over a wide period of time. This will allow the identification of potential failure modes and the study of their impacts by the way of direct mechanical investigation based on stiffness and blocking force measurements performed periodically.
A review of the models for evaluating organizational factors in human reliability analysis
International Nuclear Information System (INIS)
Alvarenga, Marco Antonio Bayout; Fonseca, Renato Alves da; Melo, Paulo Fernando Ferreira Frutuoso e
2009-01-01
Human factors should be evaluated in three hierarchical levels. The first level should concern the cognitive behavior of human beings during the control of processes that occur through the man-machine interface. Here, one evaluates human errors through human reliability models of first and second generation, like THERP, ASEP and HCR (first generation) and ATHEANA and CREAM (second generation). In the second level, the focus is in the cognitive behavior of human beings when they work in groups, as in nuclear power plants. The focus here is in the anthropological aspects that govern the interaction among human beings. In the third level, one is interested in the influence that the organizational culture exerts on human beings as well as on the tasks being performed. Here, one adds to the factors of the second level the economical and political aspects that shape the company organizational culture. Nowadays, the methodologies of HRA incorporate organizational factors in the group and organization levels through performance shaping factors. This work makes a critical evaluation of the deficiencies concerning human factors and evaluates the potential of quantitative techniques that have been proposed in the last decade to model organizational factors, including the interaction among groups, with the intention of eliminating this chronic deficiency of HRA models. Two important techniques will be discussed in this context: STAMP, based on system theory and FRAM, which aims at modeling the nonlinearities of socio-technical systems. (author)
A review of the models for evaluating organizational factors in human reliability analysis
Energy Technology Data Exchange (ETDEWEB)
Alvarenga, Marco Antonio Bayout; Fonseca, Renato Alves da [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)], e-mail: bayout@cnen.gov.br, e-mail: rfonseca@cnen.gov.br; Melo, Paulo Fernando Ferreira Frutuoso e [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear], e-mail: frutuoso@con.ufrj.br
2009-07-01
Human factors should be evaluated in three hierarchical levels. The first level should concern the cognitive behavior of human beings during the control of processes that occur through the man-machine interface. Here, one evaluates human errors through human reliability models of first and second generation, like THERP, ASEP and HCR (first generation) and ATHEANA and CREAM (second generation). In the second level, the focus is in the cognitive behavior of human beings when they work in groups, as in nuclear power plants. The focus here is in the anthropological aspects that govern the interaction among human beings. In the third level, one is interested in the influence that the organizational culture exerts on human beings as well as on the tasks being performed. Here, one adds to the factors of the second level the economical and political aspects that shape the company organizational culture. Nowadays, the methodologies of HRA incorporate organizational factors in the group and organization levels through performance shaping factors. This work makes a critical evaluation of the deficiencies concerning human factors and evaluates the potential of quantitative techniques that have been proposed in the last decade to model organizational factors, including the interaction among groups, with the intention of eliminating this chronic deficiency of HRA models. Two important techniques will be discussed in this context: STAMP, based on system theory and FRAM, which aims at modeling the nonlinearities of socio-technical systems. (author)
International Nuclear Information System (INIS)
Li Qin
2010-01-01
Characteristics of non-electric detonating circuit are introduced. The main factors influencing the reliability of non-electric detonating circuit are described. Taking an underground blasting of a uranium mine for example, the reliability of various kinds of detonating network system is calculated using the reliability theory and numerical analysis method. The reasons that cause the misfiring in non-electric detonating circuit system are analyzed, and preventive measures are put forward.(authors)
Directory of Open Access Journals (Sweden)
Leszek CHYBOWSKI
2012-01-01
Full Text Available The paper presents the need to develop a description of the importance of the technological systems reliability structure elements in terms of security of the system. Basic issues related to the exploration of weak links and important elements in the system as well as a proposal to develop the current approach to assessing the importance of the system components have been presented. Moreover, the differences between the unreliability of suitability and unreliability of safety have been pointed out.
Reliability and risk functions for structural components taking into account inspection results
International Nuclear Information System (INIS)
Rackwitz, R.; Schall, G.
1989-01-01
The method of outcrossings has been shown to be efficient when calculating the failure probability of metallic structural components under ergodic Gaussian loading. Using Paris/Erdogan's crack growth law it is possible to develop a semi-analytical calculation model for both the reliability and the risk function. For numerical studies an approximate method of asymptotic nature is proposed. The same methodology also enables to incorporate inspection observations. (orig.) [de
Effect of soil–structure interaction on the reliability of reinforced concrete bridges
Kamel Bezih; Alaa Chateauneuf; Mahdi Kalla; Claude Bacconnet
2015-01-01
In the design of reinforced concrete (RC) bridges, the random and nonlinear behavior of soil may lead to insufficient reliability levels. For this reason, it is necessary to take into account the variability of soil properties which can significantly affect the bridge behavior regarding ultimate and serviceability limit states. This study investigates the failure probability for existing reinforced concrete bridges due to the effects of interaction between the soil and the structure. In this ...
Guidelines for Interactive Reliability-Based Structural Optimization using Quasi-Newton Algorithms
DEFF Research Database (Denmark)
Pedersen, C.; Thoft-Christensen, Palle
increase of the condition number and preserve positive definiteness without discarding previously obtained information. All proposed modifications are also valid for non-interactive optimization problems. Heuristic rules from various optimization problems concerning when and how to impose interactions......Guidelines for interactive reliability-based structural optimization problems are outlined in terms of modifications of standard quasi-Newton algorithms. The proposed modifications minimize the condition number of the approximate Hessian matrix in each iteration, restrict the relative and absolute...
NAC transcription factors: structurally distinct, functionally diverse
DEFF Research Database (Denmark)
Olsen, Addie Nina; Ernst, Heidi A; Leggio, Leila Lo
2005-01-01
level and localization, and to the first indications of NAC participation in transcription factor networks. The recent determination of the DNA and protein binding NAC domain structure offers insight into the molecular functions of the protein family. Research into NAC transcription factors has......NAC proteins constitute one of the largest families of plant-specific transcription factors, and the family is present in a wide range of land plants. Here, we summarize the biological and molecular functions of the NAC family, paying particular attention to the intricate regulation of NAC protein...
Strategic planning decision making using fuzzy SWOT-TOPSIS with reliability factor
Mohamad, Daud; Afandi, Nur Syamimi; Kamis, Nor Hanimah
2015-10-01
Strategic planning is a process of decision making and action for long-term activities in an organization. The Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis has been commonly used to help organizations in strategizing their future direction by analyzing internal and external environment. However, SWOT analysis has some limitations as it is unable to prioritize appropriately the multiple alternative strategic decisions. Some efforts have been made to solve this problem by incorporating Multi Criteria Decision Making (MCDM) methods. Nevertheless, another important aspect has raised concerns on obtaining the decision that is the reliability of the information. Decision makers evaluate differently depending on their level of confidence or sureness in the evaluation. This study proposes a decision making procedure for strategic planning using SWOT-TOPSIS method by incorporating the reliability factor of the evaluation based on Z-number. An example using a local authority in the east coast of Malaysia is illustrated to determine the strategic options ranking and to prioritize factors in each SWOT category.
Probabilistic Calibration of Fatigue Design Factors for Offshore Wind Turbine Support Structures
DEFF Research Database (Denmark)
Ramirez, José Rangel; Sørensen, John Dalsgaard
2010-01-01
for the considered offshore wind turbines in such a way that the specific uncertainties for the fatigue life are accounted in a rational manner. Similar approaches have been used for offshore oil & gas sub-structures, but the required reliability level for offshore wind turbines is generally lower and the fatigue......This paper describes a reliability-based approach to determine fatigue design factors (FDF) for offshore wind turbine support structures made of steel. The FDF values are calibrated to a specific reliability level and linked to a specific inspection and maintenance (I&M) strategy used...
Sustainability of transport structures - some aspects of the nonlinear reliability assessment
Pukl, Radomír; Sajdlová, Tereza; Strauss, Alfred; Lehký, David; Novák, Drahomír
2017-09-01
Efficient techniques for both nonlinear numerical analysis of concrete structures and advanced stochastic simulation methods have been combined in order to offer an advanced tool for assessment of realistic behaviour, failure and safety assessment of transport structures. The utilized approach is based on randomization of the non-linear finite element analysis of the structural models. Degradation aspects such as carbonation of concrete can be accounted in order predict durability of the investigated structure and its sustainability. Results can serve as a rational basis for the performance and sustainability assessment based on advanced nonlinear computer analysis of the structures of transport infrastructure such as bridges or tunnels. In the stochastic simulation the input material parameters obtained from material tests including their randomness and uncertainty are represented as random variables or fields. Appropriate identification of material parameters is crucial for the virtual failure modelling of structures and structural elements. Inverse analysis using artificial neural networks and virtual stochastic simulations approach is applied to determine the fracture mechanical parameters of the structural material and its numerical model. Structural response, reliability and sustainability have been investigated on different types of transport structures made from various materials using the above mentioned methodology and tools.
Improved reliability, accuracy and quality in automated NMR structure calculation with ARIA
Energy Technology Data Exchange (ETDEWEB)
Mareuil, Fabien [Institut Pasteur, Cellule d' Informatique pour la Biologie (France); Malliavin, Thérèse E.; Nilges, Michael; Bardiaux, Benjamin, E-mail: bardiaux@pasteur.fr [Institut Pasteur, Unité de Bioinformatique Structurale, CNRS UMR 3528 (France)
2015-08-15
In biological NMR, assignment of NOE cross-peaks and calculation of atomic conformations are critical steps in the determination of reliable high-resolution structures. ARIA is an automated approach that performs NOE assignment and structure calculation in a concomitant manner in an iterative procedure. The log-harmonic shape for distance restraint potential and the Bayesian weighting of distance restraints, recently introduced in ARIA, were shown to significantly improve the quality and the accuracy of determined structures. In this paper, we propose two modifications of the ARIA protocol: (1) the softening of the force field together with adapted hydrogen radii, which is meaningful in the context of the log-harmonic potential with Bayesian weighting, (2) a procedure that automatically adjusts the violation tolerance used in the selection of active restraints, based on the fitting of the structure to the input data sets. The new ARIA protocols were fine-tuned on a set of eight protein targets from the CASD–NMR initiative. As a result, the convergence problems previously observed for some targets was resolved and the obtained structures exhibited better quality. In addition, the new ARIA protocols were applied for the structure calculation of ten new CASD–NMR targets in a blind fashion, i.e. without knowing the actual solution. Even though optimisation of parameters and pre-filtering of unrefined NOE peak lists were necessary for half of the targets, ARIA consistently and reliably determined very precise and highly accurate structures for all cases. In the context of integrative structural biology, an increasing number of experimental methods are used that produce distance data for the determination of 3D structures of macromolecules, stressing the importance of methods that successfully make use of ambiguous and noisy distance data.
Some aspects of the reliability-based design of reactor containment structures
International Nuclear Information System (INIS)
Schueller, G.I.
1975-01-01
It is generally recognized that the load which a structure is likely to experience during its design life as well as its resistance are to be represented by random variables. A rational design procedure for reactor containment structures can therefore only be carried out within a probabilistic framework. Internal load conditions caused by system failure such as loss-of-coolant accident, pressure loads etc., and external load conditions caused for instance by impact due to aircraft crashes, external pressure waves and natural hazards such as earthquakes, floods, hurricanes are described by extreme value distributions of the Fisher-Tippett types. Statistical and physical arguments are given to support their application. The occurrence of these rare events with respect to time is modeled by a Poisson process. The yield strength of the containment structure for both steel (liner) and reinforced concrete shells is also modeled by extreme value distributions (of the smallest values). The failure criterion considered here is that of collapse determined by plastic yieldline formation. A failure mechanism as considered here describes a particular regime of plastic line formation. The probability of failure of a structure under a single load application of load types likely to occur during the design life of the structure is to be determined by integrating over all possible mechanisms. Finally Freudenthal's reliability function is utilized to combine the information derived above so that a containment design for given design lifes and reliabilities is possible. (orig.) [de
Structural factoring approach for analyzing stochastic networks
Hayhurst, Kelly J.; Shier, Douglas R.
1991-01-01
The problem of finding the distribution of the shortest path length through a stochastic network is investigated. A general algorithm for determining the exact distribution of the shortest path length is developed based on the concept of conditional factoring, in which a directed, stochastic network is decomposed into an equivalent set of smaller, generally less complex subnetworks. Several network constructs are identified and exploited to reduce significantly the computational effort required to solve a network problem relative to complete enumeration. This algorithm can be applied to two important classes of stochastic path problems: determining the critical path distribution for acyclic networks and the exact two-terminal reliability for probabilistic networks. Computational experience with the algorithm was encouraging and allowed the exact solution of networks that have been previously analyzed only by approximation techniques.
Reliability Analysis-Based Numerical Calculation of Metal Structure of Bridge Crane
Directory of Open Access Journals (Sweden)
Wenjun Meng
2013-01-01
Full Text Available The study introduced a finite element model of DQ75t-28m bridge crane metal structure and made finite element static analysis to obtain the stress response of the dangerous point of metal structure in the most extreme condition. The simulated samples of the random variable and the stress of the dangerous point were successfully obtained through the orthogonal design. Then, we utilized BP neural network nonlinear mapping function trains to get the explicit expression of stress in response to the random variable. Combined with random perturbation theory and first-order second-moment (FOSM method, the study analyzed the reliability and its sensitivity of metal structure. In conclusion, we established a novel method for accurately quantitative analysis and design of bridge crane metal structure.
International Nuclear Information System (INIS)
Edwards, Lyndon
2005-01-01
Full text: The determination of accurate, reliable stresses is critical to many fields of engineering and, in particular, the structural integrity and hence, safety, of many systems. Neutron stress measurement is a non-destructive technique that uniquely provides insights into stress fields deep within components and structures. As such, it has become an increasingly important tool within the engineering community leading to improved manufacturing processes to reduce stress and distortion as well as to the definition of more precise structural integrity lifting procedures. This talk describes the current state of the art and identifies the key opportunities for improved structural integrity provided by the 2nd generation dedicated engineering stress diffractometers currently being designed and commissioned world-wide. Examples are provided covering a range of industrially relevant problems from the fields. (author)
Approximation of the Monte Carlo Sampling Method for Reliability Analysis of Structures
Directory of Open Access Journals (Sweden)
Mahdi Shadab Far
2016-01-01
Full Text Available Structural load types, on the one hand, and structural capacity to withstand these loads, on the other hand, are of a probabilistic nature as they cannot be calculated and presented in a fully deterministic way. As such, the past few decades have witnessed the development of numerous probabilistic approaches towards the analysis and design of structures. Among the conventional methods used to assess structural reliability, the Monte Carlo sampling method has proved to be very convenient and efficient. However, it does suffer from certain disadvantages, the biggest one being the requirement of a very large number of samples to handle small probabilities, leading to a high computational cost. In this paper, a simple algorithm was proposed to estimate low failure probabilities using a small number of samples in conjunction with the Monte Carlo method. This revised approach was then presented in a step-by-step flowchart, for the purpose of easy programming and implementation.
Hiller, W; Goebel, G
1999-01-01
The development and course of chronic tinnitus are determined by both biological and psychological factors. To combine these different sources of data, we developed a standardized interview to assess tinnitus history, summarize audiological findings, screen for etiological conditions, and explore tinnitus-related psychological complaints (Structured Tinnitus Interview). The results of a test-retest study with 65 tinnitus inpatients show that most of these components can be assessed with acceptable or high reliability. Further data based on 166 patients demonstrate that tinnitus annoyance was to some extent different from patterns of general psychological complaints, although there were medium intercorrelations with depression. Significant predictors of tinnitus annoyance were (a) continuous tinnitus without intervals, (b) hearing loss, (c) increasing tinnitus loudness over time, (d) poor maskability, (e) history of sudden hearing loss, and (f) associated craniomandibular disorder. Psychological distress was not significantly increased in patients whose tinnitus was associated to vascular disorder, cervical spine dysfunction, acoustic trauma, Menihre's disease, or neurological disorder.
Corroded Anchor Structure Stability/Reliability (CAS_Stab-R) Software for Hydraulic Structures
2017-12-01
Army Engineer Research and Development Center 3909 Halls Ferry Road Vicksburg, MS 39180-6199 Final report Approved for public release...and maintenance of a large inventory of concrete navigation structures. Over the last 40 years, a number of existing Corps hydraulic structures have...ORGANIZATION NAME(S) AND ADDRESS(ES) Information Technology Laboratory U.S. Army Engineer Research and Development Center 3909 Halls Ferry Road
FACTOR STRUCTURE OF FUNCTIONAL CAPABILITIES OF BODYBUILDERS
Directory of Open Access Journals (Sweden)
Predrag Milenović
2007-05-01
Full Text Available It is evident that researches in the fi eld of kineziology and sports sciences on the topic of body-building here are very rare mainly and probably because of its place in the system of hyerarchy of sports. Lack of interest in body-building and its insuffi cient popularization springs probably, among other things, from its different interpretation and, according to some people, from its ultimate goals which are not justifi ed by many. Others, experts from the fi eld of body-building, starting from the basic principles of its exercising point out its numerous positive characteristics and sides. Undoubtedly, characteristics of functional capabilities of sportspeople are specifi c for each sport or discipline. In body-building the functional sphere is bordered and defi ned by the nature of the sport’s activity itself, as well as by genetics and internal and external factors in a very complex training process of a bodu-builder. The goal of this research was determining the structure of the functional sphere of a body-builder. It was performed on the sample of 30 selected sportsmen, body-builders, of chronological age between 17 and 19 ( 6 months, members of the Sports' Club Strength ''Leskovac'', the Weight Lifters' Club '' Dubočica'' and the Body-building Club '' Dubočica'' from Leskovac. All the examiees have been submitted to training processes during a period longer than a year. For the purpose of determining the structure of the morphological sphere the Factor Analysis has been applied. Based on the data from the matrix of the Factor Structure the isolated factors can be interpreted in the following manner: The fi rst isolated factor in the sphere of applied functional variables is best defi ned by the variable of pulse under stress (FPUOP and the variable of maximum Oxygen consumption in liters per minute (FOLM. This isolated factor can be defi ned as a dimension of the transportation system of Oxygen. The second isolated factor in the
International Nuclear Information System (INIS)
Llory, A.
1991-08-01
This article starts out with comment on the existence of persistent problems inherent to probabilistic safety assessments (PSA). It first surveys existing American documents on the subject which make a certain number of criticisms on human reliability analyses, e.g. limitations due to the scant quantities of data available, lack of a basic theoretical model, non-reproducibility of analyses, etc. The article therefore examines and criticizes the epistemological bases of these analyses. One of the fundamental points stressed is that human reliability analyses do not take account of all the special features of the work situation which result in human error (so as to draw up statistical data from a sufficiently representative number of cases), and consequently lose all notion of the 'relationships' between human errors and the different aspects of the working environment. The other key points of criticism concern the collective nature of work which is not taken into account, and the frequent confusion between what operatives actually do and their formally prescribed job-tasks. The article proposes aspects to be given thought in order to overcome these difficulties, e.g. quantitative assessment of the social environment within a company, non-linear model for assessment of the accident rate, analysis of stress levels in staff on off-shore platforms. The method approaches used in these three studies are of the same type, and could be transposed to human-reliability problems. The article then goes into greater depth on thinking aimed at developing a 'positive' view of the human factor (and not just a 'negative' one, i.e. centred on human errors and organizational malfunctions), applying investigation methods developed in the occupational human sciences (occupational psychodynamics, ergonomics, occupational sociology). The importance of operatives working as actors of a team is stressed
Reliability of the NEO Five Factor Inventory short form for assessing personality after stroke.
Dwan, Toni; Ownsworth, Tamara; Donovan, Caroline; Lo, Ada Ho Yan
2017-07-01
It is well recognized that an individual's personality characteristics influence their psychological adjustment after stroke. However, there is a lack of research on the reliability of personality inventories for stroke. This study primarily aimed to evaluate the reliability of the Neuroticism, Extroversion, Openness to Experience (NEO)-Five Factor Inventory (NEO-FFI) for assessing pre-morbid personality and personality changes after stroke. Further aims were to investigate changes in personality during the hospital-to-home transition period and examine associations between personality and mood. Forty participants with stroke (52.5% male, M age=65.55 years) were recruited at time of hospital discharge and completed the NEO-FFI, Centre for Epidemiologic Studies - Depression and Geriatric Anxiety Inventory. Significant others completed an informant version of the NEO-FFI. Stroke participants were re-assessed on the NEO-FFI at 1-month and 4-months post-discharge. Forty matched controls also completed the NEO-FFI. Internal consistency was adequate for the NEO-FFI (α=0.57-0.86), although low for agreeableness. There was fair to excellent concordance between self-rated and informant versions of the NEO-FFI (ICC=0.58-0.78). Significant positive associations were found between neuroticism and mood (r=0.50-0.68), and significant negative associations were found between extraversion and mood (r=-0.33-0.36) and agreeableness and anxiety (r=-0.43). Self-ratings of stroke participants on the NEO-FFI at discharge did not significantly differ from matched controls. Extraversion levels significantly decreased, and agreeableness levels significantly increased between discharge and 1- and 4-months post-discharge. Overall, the results support the reliability of the NEO-FFI for assessing personality characteristics in the context of stroke.
Energy Technology Data Exchange (ETDEWEB)
Moan, Torgeir [Centre for Ships and Ocean Structures, Norwegian University of Science and Technology, Marine Technology Centre, Tyholt, N 7491 Trondheim (Norway)], E-mail: tormo@marin.ntnu.no; Ayala-Uraga, Efren [Department of Marine Technology, Norwegian University of Science and Technology, Marine Technology Centre, Tyholt, N 7491 Trondheim (Norway)
2008-03-15
A reliability-based model for assessment of deteriorating ships subjected to multiple environmental conditions is established. Deterioration due to combined crack growth and corrosion in structural components of a ship hull is accounted for based on a fracture mechanics formulation. The model enables to take into account the corrosion-induced increased crack growth rate in two ways: (1) the increased stress range produced by the plate thinning (wastage) effect and (2) corrosion fatigue itself. Sensitivity studies are carried out to evaluate the effect of inspection updating on a production ship subjected to two different climate conditions. The hazard rate concept is adopted as a measure of reliability and emphasized throughout the different case studies.
On New Cautious Structural Reliability Models in the Framework of imprecise Probabilities
DEFF Research Database (Denmark)
Utkin, Lev V.; Kozine, Igor
2010-01-01
models and gen-eralizing conventional ones to imprecise probabili-ties. The theoretical setup employed for this purpose is imprecise statistical reasoning (Walley 1991), whose general framework is provided by upper and lower previsions (expectations). The appeal of this theory is its ability to capture......Uncertainty of parameters in engineering design has been modeled in different frameworks such as inter-val analysis, fuzzy set and possibility theories, ran-dom set theory and imprecise probability theory. The authors of this paper for many years have been de-veloping new imprecise reliability...... both aleatory (stochas-tic) and epistemic uncertainty and the flexibility with which information can be represented. The previous research of the authors related to generalizing structural reliability models to impre-cise statistical measures is summarized in Utkin & Kozine (2002) and Utkin (2004...
Fatigue Reliability and Calibration of Fatigue Design Factors for Offshore Wind Turbines
DEFF Research Database (Denmark)
Dominguez, Sergio Marquez; Sørensen, John Dalsgaard
2012-01-01
Consequences of failure of offshore wind turbines (OWTs) are in general lower than consequences of failure of, e.g., oil & gas platforms. It is reasonable that lower fatigue design factors can be applied for fatigue design of OWTs when compared to other fixed offshore structures. Calibration...
Buczyński, P.
2018-05-01
This article presents a new approach to reliability assessment of the road structure in which the base layer will be constructed in the process of cold deep recycling with foamed bitumen. In order to properly assess the reliability of the structure with the recycled base, it is necessary to determine the distribution of stress and strain in typical pavement layer systems. The true stress and strain values were established for particular structural layers using the complex modulus (E*) determined based on the master curves. The complex modulus was determined by the direct tension-compression test on cylindrical specimens (DTC-CY) at five temperatures (-7°C, 5°C, 13°C, 25°C, 40°C) and six loading times (0.1 Hz, 0.3 Hz, 1 Hz, 3 Hz, 10 Hz, 20 Hz) in accordance with EN 12697-26 in the linear viscoelasticity (LVE) range for small strains ranging from 25 to 50 με. The master curves of the complex modulus were constructed using the Richards model for the mixtures typically incorporated in structural layers, i.e., SMA11, AC16W, AC22P and MCAS. The values of the modulus characterizing particular layers were determined with temperature distribution in the structure taken into account, when the surface temperature was 40°C. The stress distribution was established for those calculation models. The stress values were used to evaluate the fatigue life under controlled stress conditions (IT-FT). This evaluation, with the controlled stress corresponding to that in the structure, facilitated the quality assessment of the rehabilitated recycled base course. Results showed that the recycled base mixtures having the indirect tensile strength (ITSDRY) similar to the stress in the structure under analysis needed an additional fatigue life evaluation in the indirect tensile test ITT. This approach to the recycled base quality assessment will allow eliminating the damage induced by overloading.
The Factor Structure and Validity of the Persian Version of the Baumrind Parenting Style Inventory
Directory of Open Access Journals (Sweden)
اصغر مینائی
2017-06-01
Full Text Available In this study, the factor structure and validity of the Persian version of the Baumrind parenting style inventory were evaluated among 576 mothers of elementary school students in Tehran who had been selected through multistage cluster sampling method. This study is, due to its subject and purposes a descriptive study based on psychometric methods. The factor structure of the inventory was tested by AMOS software based on the fitting and modification indicators in the confirmatory factor analysis. The results showed that all items of the parenting style inventory except the items of 24, 8, 13, 18, assess the previously determined factors of the inventory, and that the inventory’s questions have a relatively good validity. Also, stratified alpha was used to calculate the reliability of the whole inventory, and Guttman coefficient was utilized to calculate the reliability of subscales. The outcomes indicated that the inventory and its subscales possess a relatively good reliability.
Structure factors for the alternating Heisenberg chain
International Nuclear Information System (INIS)
Hamer, C.J.; Zheng, W.
2004-01-01
Full text: We develop a linked cluster method to calculate the spectral weights of many-particle excitations at zero temperature. The dynamical structure factor, which is measured in neutron scattering experiments, is expressed as a sum of 'exclusive' structure factors, each representing the contribution of a specific excited state. We apply these methods to the alternating Heisenberg chain, where complete wave-vector and frequency dependent spectral weights for one- and two-particle excitations (continuum and bound states) are calculated near the dimerized limit (λ = O). We also examine the variation of the spectral weights as the uniform chain (λ = 1) is approached. In agreement with Schmidt and Uhrig, we find that the spectral weight is dominated by 2-triplet states, even at λ 1, which implies that a description in terms of triplet-pair excitations remains a good quantitative description even for the uniform, undimerized chain
International Nuclear Information System (INIS)
Kettunen, J.; Norros, L.
1996-04-01
The aim of the study is to chart human and organisational factors influencing the reliability of non-destructive testing (NDT). The emphasis will be in ultrasonic testing (UT) and in the planning and execution of in-service inspections during nuclear power plant maintenance outages. Being a literary survey this study is mainly based on the foreign and domestic research available on the topic. In consequence, the results presented in this report reflect the ideas of international research community. In addition to this, Finnish nuclear power plant operators (Imatran Voima Oy and Teollisuuden Voima Oy), independent inspection organisations and the Finnish Centre for Radiation and Nuclear Safety have provided us with valuable information on NDT theory and practice. Especially, a kind of 'big picture' of non-destructive testing has been pursued in the study. (6 figs., 2 tabs.)
Halo Models of Large Scale Structure and Reliability of Cosmological N-Body Simulations
Directory of Open Access Journals (Sweden)
José Gaite
2013-05-01
Full Text Available Halo models of the large scale structure of the Universe are critically examined, focusing on the definition of halos as smooth distributions of cold dark matter. This definition is essentially based on the results of cosmological N-body simulations. By a careful analysis of the standard assumptions of halo models and N-body simulations and by taking into account previous studies of self-similarity of the cosmic web structure, we conclude that N-body cosmological simulations are not fully reliable in the range of scales where halos appear. Therefore, to have a consistent definition of halos is necessary either to define them as entities of arbitrary size with a grainy rather than smooth structure or to define their size in terms of small-scale baryonic physics.
International Nuclear Information System (INIS)
Ellingwood, B.R.; Mori, Y.
1995-01-01
Research is being conducted to address aging management of safety-related reinforced concrete structures in nuclear power plants (NPPs). Documentation is being prepared to identify potential structural safety issues and to recommend criteria for use in evaluating reinforced concrete structures for continued service. Time-dependent reliability analysis provides the framework and quantitative tools for the condition assessment. The role of in-service inspection and repair in ensuring continued reliability in-service is examined. (author). 19 refs., 4 figs
International Nuclear Information System (INIS)
Griffith, Candice D.; Mahadevan, Sankaran
2015-01-01
This paper develops a probabilistic approach that could use empirical data to derive values of performance shaping factor (PSF) multipliers for use in quantitative human reliability analysis (HRA). The proposed approach is illustrated with data on sleep deprivation effects on performance. A review of existing HRA methods reveals that sleep deprivation is not explicitly included at present, and expert opinion is frequently used to inform HRA model multipliers. In this paper, quantitative data from empirical studies regarding the effect of continuous hours of wakefulness on performance measures (reaction time, accuracy, and number of lapses) are used to develop a method to derive PSF multiplier values for sleep deprivation, in the context of the SPAR-H model. Data is extracted from the identified studies according to the meta-analysis research synthesis method and used to investigate performance trends and error probabilities. The error probabilities in test and control conditions are compared, and the resulting probability ratios are suggested for use in informing the selection of PSF multipliers in HRA methods. Although illustrated for sleep deprivation, the proposed methodology is general, and can be applied to other performance shaping factors. - Highlights: • Method proposed to derive performance shaping factor multipliers from empirical data. • Studies reporting the effect of sleep deprivation on performance are analyzed. • Test data using psychomotor vigilance tasks are analyzed. • Error probability multipliers computed for reaction time, lapses, and accuracy measures.
Regression analysis of the structure function for reliability evaluation of continuous-state system
International Nuclear Information System (INIS)
Gamiz, M.L.; Martinez Miranda, M.D.
2010-01-01
Technical systems are designed to perform an intended task with an admissible range of efficiency. According to this idea, it is permissible that the system runs among different levels of performance, in addition to complete failure and the perfect functioning one. As a consequence, reliability theory has evolved from binary-state systems to the most general case of continuous-state system, in which the state of the system changes over time through some interval on the real number line. In this context, obtaining an expression for the structure function becomes difficult, compared to the discrete case, with difficulty increasing as the number of components of the system increases. In this work, we propose a method to build a structure function for a continuum system by using multivariate nonparametric regression techniques, in which certain analytical restrictions on the variable of interest must be taken into account. Once the structure function is obtained, some reliability indices of the system are estimated. We illustrate our method via several numerical examples.
Regression analysis of the structure function for reliability evaluation of continuous-state system
Energy Technology Data Exchange (ETDEWEB)
Gamiz, M.L., E-mail: mgamiz@ugr.e [Departamento de Estadistica e I.O., Facultad de Ciencias, Universidad de Granada, Granada 18071 (Spain); Martinez Miranda, M.D. [Departamento de Estadistica e I.O., Facultad de Ciencias, Universidad de Granada, Granada 18071 (Spain)
2010-02-15
Technical systems are designed to perform an intended task with an admissible range of efficiency. According to this idea, it is permissible that the system runs among different levels of performance, in addition to complete failure and the perfect functioning one. As a consequence, reliability theory has evolved from binary-state systems to the most general case of continuous-state system, in which the state of the system changes over time through some interval on the real number line. In this context, obtaining an expression for the structure function becomes difficult, compared to the discrete case, with difficulty increasing as the number of components of the system increases. In this work, we propose a method to build a structure function for a continuum system by using multivariate nonparametric regression techniques, in which certain analytical restrictions on the variable of interest must be taken into account. Once the structure function is obtained, some reliability indices of the system are estimated. We illustrate our method via several numerical examples.
International Nuclear Information System (INIS)
Sobey, A.J.; Blake, J.I.R.; Shenoi, R.A.
2013-01-01
Composite materials are often utilised for their high strength to weight ratio, excellent corrosion resistance, etc. but are also characterised by variabilities and uncertainties in their mechanical properties owing to the material make-up, process and fabrication techniques. It is essential that modelling techniques continue to be developed to take account of these variabilities and uncertainties and as more complicated structures are developed it is important to have rapid assessment methods to determine the reliability of these structures. Grillage analysis methods have been previously used for assessment of tophat stiffened composite structures using simple failure criteria. As new criteria are introduced, such as by the World Wide Failure Exercise, the response of more complex topologies must be introduced. This paper therefore assesses the reliability of composite grillages using Navier grillage method incorporating up to date failure criteria. An example, taken from boatbuilding, is used to show the results of using these more complex assessment methods showing that it is of high importance to use the correct assessment criteria.
International Nuclear Information System (INIS)
Do, Duy Minh; Gao, Wei; Song, Chongmin; Tangaramvong, Sawekchai
2014-01-01
This paper presents the non-deterministic dynamic analysis and reliability assessment of structures with uncertain-but-bounded parameters under stochastic process excitations. Random ground acceleration from earthquake motion is adopted to illustrate the stochastic process force. The exact change ranges of natural frequencies, random vibration displacement and stress responses of structures are investigated under the interval analysis framework. Formulations for structural reliability are developed considering the safe boundary and structural random vibration responses as interval parameters. An improved particle swarm optimization algorithm, namely randomised lower sequence initialized high-order nonlinear particle swarm optimization algorithm, is employed to capture the better bounds of structural dynamic characteristics, random vibration responses and reliability. Three numerical examples are used to demonstrate the presented method for interval random vibration analysis and reliability assessment of structures. The accuracy of the results obtained by the presented method is verified by the randomised Quasi-Monte Carlo simulation method (QMCSM) and direct Monte Carlo simulation method (MCSM). - Highlights: • Interval uncertainty is introduced into structural random vibration responses. • Interval dynamic reliability assessments of structures are implemented. • Boundaries of structural dynamic response and reliability are achieved
DEFF Research Database (Denmark)
Nielsen, Søren R.K.; Sørensen, John Dalsgaard; Thoft-Christensen, Palle
1983-01-01
plastic deformation during several loadings can be modelled as a filtered Poisson process. Using the Markov property of this quantity the considered first-passage problem as well as the related extreme distribution problems are then solved numerically, and the results are compared to simulation studies.......A method is presented for life-time reliability' estimates of randomly excited yielding systems, assuming the structure to be safe, when the plastic deformations are confined below certain limits. The accumulated plastic deformations during any single significant loading history are considered...
Grant, Jon E; Kim, Suck Won; McCabe, James S
2006-06-01
Kleptomania presents difficulties in diagnosis for clinicians. This study aimed to develop and test a DSM-IV-based diagnostic instrument for kleptomania. To assess for current kleptomania the Structured Clinical Interview for Kleptomania (SCI-K) was administered to 112 consecutive subjects requesting psychiatric outpatient treatment for a variety of disorders. Reliability and validity were determined. Classification accuracy was examined using the longitudinal course of illness. The SCI-K demonstrated excellent test-retest (Phi coefficient = 0.956 (95% CI = 0.937, 0.970)) and inter-rater reliability (phi coefficient = 0.718 (95% CI = 0.506, 0.848)) in the diagnosis of kleptomania. Concurrent validity was observed with a self-report measure using DSM-IV kleptomania criteria (phi coefficient = 0.769 (95% CI = 0.653, 0.850)). Discriminant validity was observed with a measure of depression (point biserial coefficient = -0.020 (95% CI = -0.205, 0.166)). The SCI-K demonstrated both high sensitivity and specificity based on longitudinal assessment. The SCI-K demonstrated excellent reliability and validity in diagnosing kleptomania in subjects presenting with various psychiatric problems. These findings require replication in larger groups, including non-psychiatric populations, to examine their generalizability. Copyright (c) 2006 John Wiley & Sons, Ltd.
Ceramics Analysis and Reliability Evaluation of Structures (CARES). Users and programmers manual
Nemeth, Noel N.; Manderscheid, Jane M.; Gyekenyesi, John P.
1990-01-01
This manual describes how to use the Ceramics Analysis and Reliability Evaluation of Structures (CARES) computer program. The primary function of the code is to calculate the fast fracture reliability or failure probability of macroscopically isotropic ceramic components. These components may be subjected to complex thermomechanical loadings, such as those found in heat engine applications. The program uses results from MSC/NASTRAN or ANSYS finite element analysis programs to evaluate component reliability due to inherent surface and/or volume type flaws. CARES utilizes the Batdorf model and the two-parameter Weibull cumulative distribution function to describe the effect of multiaxial stress states on material strength. The principle of independent action (PIA) and the Weibull normal stress averaging models are also included. Weibull material strength parameters, the Batdorf crack density coefficient, and other related statistical quantities are estimated from four-point bend bar or unifrom uniaxial tensile specimen fracture strength data. Parameter estimation can be performed for single or multiple failure modes by using the least-square analysis or the maximum likelihood method. Kolmogorov-Smirnov and Anderson-Darling goodness-of-fit tests, ninety percent confidence intervals on the Weibull parameters, and Kanofsky-Srinivasan ninety percent confidence band values are also provided. The probabilistic fast-fracture theories used in CARES, along with the input and output for CARES, are described. Example problems to demonstrate various feature of the program are also included. This manual describes the MSC/NASTRAN version of the CARES program.
DEFF Research Database (Denmark)
Katsanos, E. I.; Sextos, A. G.
2018-01-01
A decision support process is presented to accommodate selecting and scaling of earthquake motions as required for the time domain analysis of structures. Code-compatible suites of seismic motions are provided being, at the same time, prequalified through a multi-criterion approach to induce...... was subjected to numerous suites of motions that were highly ranked according to both the proposed approach (δsv–sc) and the conventional one (δconv), that is commonly used for earthquake records selection and scaling. The findings from numerous linear response history analyses reveal the superiority...
Martowicz, Adam; Uhl, Tadeusz
2012-10-01
The paper discusses the applicability of a reliability- and performance-based multi-criteria robust design optimization technique for micro-electromechanical systems, considering their technological uncertainties. Nowadays, micro-devices are commonly applied systems, especially in the automotive industry, taking advantage of utilizing both the mechanical structure and electronic control circuit on one board. Their frequent use motivates the elaboration of virtual prototyping tools that can be applied in design optimization with the introduction of technological uncertainties and reliability. The authors present a procedure for the optimization of micro-devices, which is based on the theory of reliability-based robust design optimization. This takes into consideration the performance of a micro-device and its reliability assessed by means of uncertainty analysis. The procedure assumes that, for each checked design configuration, the assessment of uncertainty propagation is performed with the meta-modeling technique. The described procedure is illustrated with an example of the optimization carried out for a finite element model of a micro-mirror. The multi-physics approach allowed the introduction of several physical phenomena to correctly model the electrostatic actuation and the squeezing effect present between electrodes. The optimization was preceded by sensitivity analysis to establish the design and uncertain domains. The genetic algorithms fulfilled the defined optimization task effectively. The best discovered individuals are characterized by a minimized value of the multi-criteria objective function, simultaneously satisfying the constraint on material strength. The restriction of the maximum equivalent stresses was introduced with the conditionally formulated objective function with a penalty component. The yielded results were successfully verified with a global uniform search through the input design domain.
International Nuclear Information System (INIS)
Duewer, D.L.
1977-01-01
Pattern recognition techniques are applied to the analysis of white bond papers and the problem of determining the source of an oil spill. In each case, an elemental analysis by neutron activation is employed. For the determination of source of oil spills, the field sample was weathered prior to activation analysis. A procedure for including measured analytical uncertainty into data analysis methodology is discussed, with particular reference to factor analysis. The suitability of various dispersion matrices and matrix rank determination criteria for data having analytical uncertainty is investigated. A criterion useful for judging the number of factors insensitive to analytical uncertainty is presented. A model data structure for investigating the behavior of factor analysis techniques in a known, controlled manner is described and analyzed. A chemically interesting test data base having analytical uncertainty is analyzed and compared with the model data. The data structure of 22 blood constituents in three categories of liver disease (viral or toxic hepatitis, alcoholic liver diseases and obstructive processes) is studied using various statistical and pattern recognition techniques. Comparison of classification results on the original data, in combination with principal component analysis, suggests a possible underlying structure for the data. This model structure is tested by the application of two simple data transformations. Analysis of the transformed data appears to confirm that some basic understanding of the studied data has been achieved
International Nuclear Information System (INIS)
Meyer, T.A.; Balkey, K.R.; Bishop, B.A.
1987-01-01
There can be numerous uncertainties involved in performing component life assessments. In addition, sufficient data may be unavailable to make a useful life prediction. Structural Reliability and Risk Assessment (SRRA) is primarily an analytical methodology or tool that quantifies the impact of uncertainties on the structural life of plant components and can address the lack of data in component life prediction. As a prelude to discussing the technical aspects of SRRA, a brief review of general component life prediction methods is first made so as to better develop an understanding of the role of SRRA in such evaluations. SRRA is then presented as it is applied in component life evaluations with example applications being discussed for both nuclear and non-nuclear components
Effect of steel structure and defects on reliability of parts of impact mechanisms
Popelyukh, AI; Repin, AA; Alekseev, SE
2018-03-01
The paper discusses selection of materials suitable for manufacturing critical parts of impact mechanisms. It is shown that in order to extend life of parts exposed to high dynamic loading, it is expedient to use medium- and high-carbon alloy-treated steels featuring low impurity with nonmetallic inclusions and high hardening characteristics. Application of thermally untreated parts is undesirable as steel having ferrite–pearlite structure possesses low fatigue strength. Aimed to ensure high reliability of parts with a hardness of 42–55 HRC, steel should be reinforced by thermal treatement with the formation of multicomponent martensite–bainite structure. High-quality production should include defectoscopy and incoming material control.
Reliability study of ultra-thin gate oxides on strained-Si/SiGe MOS structures
International Nuclear Information System (INIS)
Varzgar, John B.; Kanoun, Mehdi; Uppal, Suresh; Chattopadhyay, Sanatan; Tsang, Yuk Lun; Escobedo-Cousins, Enrique; Olsen, Sarah H.; O'Neill, Anthony; Hellstroem, Per-Erik; Edholm, Jonas; Ostling, Mikael; Lyutovich, Klara; Oehme, Michael; Kasper, Erich
2006-01-01
The reliability of gate oxides on bulk Si and strained Si (s-Si) has been evaluated using constant voltage stressing (CVS) to investigate their breakdown characteristics. The s-Si architectures exhibit a shorter life time compared to that of bulk Si, which is attributed to higher bulk oxide charges (Q ox ) and increased surface roughness in the s-Si structures. The gate oxide in the s-Si structure exhibits a hard breakdown (HBD) at 1.9 x 10 4 s, whereas HBD is not observed in bulk Si up to a measurement period of 1.44 x 10 5 s. The shorter lifetime of the s-Si gate oxide is attributed to a larger injected charge (Q inj ) compared to Q inj in bulk Si. Current-voltage (I-V) measurements for bulk Si samples at different stress intervals show an increase in stress induced leakage current (SILC) of two orders in the low voltage regime from zero stress time to up to 5 x 10 4 s. In contrast, superior performance enhancements in terms of drain current, maximum transconductance and effective channel mobility are observed in s-Si MOSFET devices compared to bulk Si. The results from this study indicate that further improvement in gate oxide reliability is needed to exploit the sustained performance enhancement of s-Si devices over bulk Si
Xu, Jun; Kong, Fan
2018-05-01
Extreme value distribution (EVD) evaluation is a critical topic in reliability analysis of nonlinear structural dynamic systems. In this paper, a new method is proposed to obtain the EVD. The maximum entropy method (MEM) with fractional moments as constraints is employed to derive the entire range of EVD. Then, an adaptive cubature formula is proposed for fractional moments assessment involved in MEM, which is closely related to the efficiency and accuracy for reliability analysis. Three point sets, which include a total of 2d2 + 1 integration points in the dimension d, are generated in the proposed formula. In this regard, the efficiency of the proposed formula is ensured. Besides, a "free" parameter is introduced, which makes the proposed formula adaptive with the dimension. The "free" parameter is determined by arranging one point set adjacent to the boundary of the hyper-sphere which contains the bulk of total probability. In this regard, the tail distribution may be better reproduced and the fractional moments could be evaluated with accuracy. Finally, the proposed method is applied to a ten-storey shear frame structure under seismic excitations, which exhibits strong nonlinearity. The numerical results demonstrate the efficacy of the proposed method.
Directory of Open Access Journals (Sweden)
Marco Mula
2008-08-01
Full Text Available Marco Mula, Stefano Pini, Simona Calugi, Matteo Preve, Matteo Masini, Ilaria Giovannini, Ciro Conversano, Paola Rucci, Giovanni B CassanoDepartment of Psychiatry, Neurobiology, Pharmacology and Biotechnologies, University of Pisa, ItalyAbstract: This study evaluates the validity and reliability of a new instrument developed to assess symptoms of depersonalization: the Structured Clinical Interview for the Depersonalization-Derealization Spectrum (SCI-DER. The instrument is based on a spectrum model that emphasizes soft-signs, sub-threshold syndromes as well as clinical and subsyndromal manifestations. Items of the interview include, in addition to DSM-IV criteria for depersonalization, a number of features derived from clinical experience and from a review of phenomenological descriptions. Study participants included 258 consecutive patients with mood and anxiety disorders, 16.7% bipolar I disorder, 18.6% bipolar II disorder, 32.9% major depression, 22.1% panic disorder, 4.7% obsessive compulsive disorder, and 1.5% generalized anxiety disorder; 2.7% patients were also diagnosed with depersonalization disorder. A comparison group of 42 unselected controls was enrolled at the same site. The SCI-DER showed excellent reliability and good concurrent validity with the Dissociative Experiences Scale. It significantly discriminated subjects with any diagnosis of mood and anxiety disorders from controls and subjects with depersonalization disorder from controls. The hypothesized structure of the instrument was confirmed empirically.Keywords: depersonalization, derealization, mood disorders, anxiety disorders
International Nuclear Information System (INIS)
Minato, Akio
1983-08-01
Static and dynamic structural analyses of the vacuum vessel for a Swimming Pool Type Tokamak Reactor (SPTR) have been conducted under the external pressure (hydraulic and atmospheric pressure) during normal operation or the electromagnetic force due to plasma disruption. The reactor structural design is based on the concept that the adjacent modules of the vacuum vessel are not connected mechanically with bolts in the torus inboard region each other, so as to save the required space for inserting the remote handling machine for tightenning and untightenning bolts in the region and to simplify the repair and maintenance of the reactor. The structural analyses of the vacuum vessel have been carried out under the external pressure and the electromagnetic force and the structural reliability against the static and dynamic loads is estimated. The several configurations of the lip seal between the modules, which is required to make a plasma vacuum boundary, have been proposed and the structural strength under the forced displacements due to the deformation of the vacuum vessel is also estimated. (author)
Dynamic structure factor on liquid Pb
International Nuclear Information System (INIS)
Padureanu, I.; Rapeanu, S.; Rotarascu, G.; Craciun, C.
1979-01-01
Dinamic structure factor S(Q,hω) in liquid Pb has been measured at 350 deg C and 400 deg C using the inelastic scattering of the slow neutrons. The measurements were performed in the momentum transfer range 0.6 A -1 -1 . The intermediate scattering function F(Q,t) is also calculated from S(Q,hω). Multiple scattering calculation shows that it is very large especially at small scattering angles. The comparison of the experimental data with the theory is made in terms of two theoretical models. (author)
Static structure factor of liquid parahydrogen
International Nuclear Information System (INIS)
Dawidowski, J.; Bermejo, F.J.; Ristig, M.L.; Faak, B.; Cabrillo, C.; Fernandez-Perea, R.; Kinugawa, K.; Campo, J.
2004-01-01
The single-differential neutron-scattering cross section of liquid parahydrogen has been measured at 15.2 K and 2 bars of applied pressure by means of low-energy neutron diffraction. Our experimental conditions enable the direct observation of the peak of the liquid structure factor and therefore largely improve the signal-to-noise ratio with respect to measurements carried out using higher-energy neutron diffraction. This avoids the need of performing corrections of approximate nature to the measured cross section that is dominated by molecular rotational components if measured by conventional neutron diffraction
The factor structure of six salutogenic constructs
Directory of Open Access Journals (Sweden)
Marita Breed
2006-10-01
Full Text Available The aim of this research was to investigate the factor structure of six salutogenic constructs, namely sense of coherence, hardiness, learned resourcefulness, potency, internal locus of control and self-efficacy. Measurement with a sample of 935 part-time students did not fit the conceptualisation of salutogenesis. A different factor structure for Whites versus Others occurred. For Whites, all six constructs more or less contributed towards the general salutogenic factor and for Others all but learned resourcefulness contributed. For Whites, salutogenesis consisted of two clear dimensions (a global positive orientation; specific behavioural skills and for Others one dimension (an optimistic life view. Confirmatory factor analysis performed on the data for both groups, indicated a weak fit. It was recommended that salutogenesis be further explored within an overall personality theory. Opsomming Die doel van hierdie navorsing was om die faktorstruktuur van ses salutogeniese konstrukte te ondersoek, naamlik sin vir koherensie, gehardheid, aangeleerde vindingrykheid, potensie, interne lokus van beheer en selfgenoegsaamheid. Meting met ‘n steekproef van 935 deeltydse studente het nie ‘n passing getoon met die konseptualisering van salutogenese nie. ‘n Eiesoortige faktorstruktuur vir Wit studente versus Ander studente het voorgekom. Vir Wittes, het al ses die konstrukte meer of minder bygedra tot die algemene salutugeniese faktor en vir Andere het almal behalwe aangeleerde vindingrykheid bygedra. Vir Wittes bestaan salutogenese uit twee duidelike dimensies (‘n globale positiewe lewensorientasie; spesifieke gedrags vaardighede en vir Andere uit een dimensie (‘n optimistiese lewensbeskouing. Bevestigende faktor ontleding uitgevoer op die data van beide groepe, het ‘n swak passing getoon. Daar is aanbeveel dat salutogenese verder ondersoek word binne ‘n oorkoepelende persoonlikheidsteorie.
Hulsman, R. L.; Mollema, E. D.; Oort, F. J.; Hoos, A. M.; de Haes, J. C. J. M.
2006-01-01
OBJECTIVE: Using standardized video cases in a computerized objective structured video examination (OSVE) aims to measure cognitive scripts underlying overt communication behavior by questions on knowledge, understanding and performance. In this study the reliability of the OSVE assessment is
International Nuclear Information System (INIS)
Jennerich, Marco; Imbsweiler, Jonas; Straeter, Oliver; Arenius, Marcus
2015-03-01
This report presents the findings of the project for the consideration of human factor in the quantification of the reliability of technical systems, taking into account cognitive-causal aspects concerning the modeling of human behavior of reliability issues (funded by the Federal Ministry of Economics and Technology; grant number 15014328). This project is part of a joint project with the University of Applied Sciences Zittau / Goerlitz for assessing the human factor in the quantification of the reliability of technical systems. The concern of the University of Applied Sciences Zittau / Goerlitz is the mathematical modeling of human reliability by means of a fuzzy set approach (grant number 1501432A). The part of the project presented here provides the necessary data basis for the evaluation of the mathematical modeling using fuzzy set approach. At the appropriate places in this report, the interfaces and data bases between the two projects are outlined accordingly. HRA-methods (Human Reliability Analysis) are an essential component to analyze the reliability of socio-technical systems. Various methods have been established and are used in different areas of application. The established HRA methods have been checked on their congruence. In particular the underlying models and their parameters such as performance-influencing factors and situational influences have been investigated. The elaborated parameters were combined into a hierarchical class structure. Cross-domain incidents were studied. The specific performance-influencing factors have been worked out and have been integrated into a cross-domain database. The dominant (critical) situational factors and their interactions within the event data were identified using the CAHR method (connectionism Assessment of Human Reliability). Task dependent cognitive load profiles have been defined. Within these profiles qualitative and quantitative data of the possibility of emergence of errors have been acquired. This
On structural reliability under time-varying multi-parameter loading
International Nuclear Information System (INIS)
Augusti, G.
1975-01-01
Special attention will be paid to the superimposition of loads of different origin and characteristics (e.g. long-term loads like the furniture and usual occupancy load in a building and short-term loads like explosions, earthquakes, storms, etc.): it will be recognized that a single procedure for all cases does not appear practical, and that, within a general framework special method must be devised according to the type of loads and structural responses. For instance, the superimposition of impulsive loads must be studied with reference to the response time of the structure. It will be shown that usually, the statistics of extreme values are not sufficient for a correct study of superimposition: the instantaneous probability distributions of the load intensities are also required. The results obtained with respect to the loads can be joined with previous results by Augusti and Baratta (see e.g. SMiRT-2 paper M7/8) on structural strength, for the evaluation of the probability of success (i.e. the reliability) of a structural design
Moving Aerospace Structural Design Practice to a Load and Resistance Factor Approach
Larsen, Curtis E.; Raju, Ivatury S.
2016-01-01
Aerospace structures are traditionally designed using the factor of safety (FOS) approach. The limit load on the structure is determined and the structure is then designed for FOS times the limit load - the ultimate load. Probabilistic approaches utilize distributions for loads and strengths. Failures are predicted to occur in the region of intersection of the two distributions. The load and resistance factor design (LRFD) approach judiciously combines these two approaches by intensive calibration studies on loads and strength to result in structures that are efficient and reliable. This paper discusses these three approaches.
2013-01-01
Background The assessment of personality organization and its observable behavioral manifestations, i.e. personality functioning, has a long tradition in psychodynamic psychiatry. Recently, the DSM-5 Levels of Personality Functioning Scale has moved it into the focus of psychiatric diagnostics. Based on Kernberg’s concept of personality organization the Structured Interview of Personality Organization (STIPO) was developed for diagnosing personality functioning. The STIPO covers seven dimensions: (1) identity, (2) object relations, (3) primitive defenses, (4) coping/rigidity, (5) aggression, (6) moral values, and (7) reality testing and perceptual distortions. The English version of the STIPO has previously revealed satisfying psychometric properties. Methods Validity and reliability of the German version of the 100-item instrument have been evaluated in 122 psychiatric patients. All patients were diagnosed according to the Diagnostic and Statistical Manual for Mental Disorders (DSM-IV) and were assessed by means of the STIPO. Moreover, all patients completed eight questionnaires that served as criteria for external validity of the STIPO. Results Interrater reliability varied between intraclass correlations of .89 and 1.0, Crohnbach’s α for the seven dimensions was .69 to .93. All a priori selected questionnaire scales correlated significantly with the corresponding STIPO dimensions. Patients with personality disorder (PD) revealed significantly higher STIPO scores (i.e. worse personality functioning) than patients without PD; patients cluster B PD showed significantly higher STIPO scores than patients with cluster C PD. Conclusions Interrater reliability, Crohnbach’s α, concurrent validity, and differential validity of the STIPO are satisfying. The STIPO represents an appropriate instrument for the assessment of personality functioning in clinical and research settings. PMID:23941404
Metacognition Assessment Interview: Instrument description and factor structure
Directory of Open Access Journals (Sweden)
Giovanni Pellecchia
2015-12-01
Full Text Available Objective: Metacognition is a multi-component psychological construct, characterised by the ability to identify and describe one’s own mental states and those of others. Evidence has been found for an association between deficits in metacognitive abilities and poor social functioning, low quality of life, psychopathology, and symptoms in Personality Disorders (PDs. However, to date, there are few psychometrically validated instruments available for assessing the different components of metacognition. A semi-structured interview, the Metacognition Assessment Interview (MAI, has been developed to evaluate different domains of metacognition. In the present study, we investigated the psychometric properties of the MAI in an outpatient clinical sample. Method: The MAI was administered to a clinical population of 306 outpatients attending a private clinical centre. Exploratory factor analysis, confirmatory factor analysis and correlation with instruments assessing alexithymia and interpersonal problems were carried out to examine the dimensionality and validity of the MAI. Result: Explorative and confirmatory factor analyses revealed a good fit for both a two-factor model and a four-factor model of metacognition. The two-factor model yielded two main dimensions, which we named: Self domain, defined as self-reflection, and Other domain, defined as critical distancing from one’s own mental state and that of others. The four-factor solution is composed of four sub-domains: monitoring, integration, differentiation and decentration. Moreover, the MAI showed good convergent validity, with significant correlations with both alexithymia and interpersonal problems. Conclusions: These results confirm that the MAI is a reliable instrument for measuring metacognition and its different sub-domains. In particular, the MAI represents a useful and flexible instrument for the assessment of metacognition impairments in different psychopathologies and it can provide
Dalton, Michelle; Hollingworth, Sophie; Blundell, John; Finlayson, Graham
2015-09-04
Some individuals exhibit a weak satiety response to food and may be susceptible to overconsumption. The current study identified women showing consistently low or high satiety responses to standardised servings of food across four separate days and compared them on behavioural, psychological and physiological risk factors for overeating and future weight gain. In a crossover design, 30 female participants (age: 28.0 ± 10.6; body mass index (BMI): 23.1 ± 3.0) recorded sensations of hunger in the post-prandial period following four graded energy level breakfasts. Satiety quotients were calculated to compare individuals on satiety responsiveness across conditions. Body composition, resting metabolic rate (RMR), energy intake, food reward and craving, and eating behaviour traits were assessed under controlled laboratory conditions. A distinct low satiety phenotype (LSP) was identified with good consistency across separate study days. These individuals had a higher RMR, greater levels of disinhibition and reported feeling lower control over food cravings. Further, they consumed more energy and exhibited greater wanting for high-fat food. The inverse pattern of characteristics was observed in those exhibiting a consistently high satiety phenotype (HSP). Weak satiety responsiveness is a reliable trait identifiable using the satiety quotient. The LSP was characterised by distinct behavioural and psychological characteristics indicating a risk for overeating, compared to HSP.
Directory of Open Access Journals (Sweden)
Michelle Dalton
2015-09-01
Full Text Available Some individuals exhibit a weak satiety response to food and may be susceptible to overconsumption. The current study identified women showing consistently low or high satiety responses to standardised servings of food across four separate days and compared them on behavioural, psychological and physiological risk factors for overeating and future weight gain. In a crossover design, 30 female participants (age: 28.0 ± 10.6; body mass index (BMI: 23.1 ± 3.0 recorded sensations of hunger in the post-prandial period following four graded energy level breakfasts. Satiety quotients were calculated to compare individuals on satiety responsiveness across conditions. Body composition, resting metabolic rate (RMR, energy intake, food reward and craving, and eating behaviour traits were assessed under controlled laboratory conditions. A distinct low satiety phenotype (LSP was identified with good consistency across separate study days. These individuals had a higher RMR, greater levels of disinhibition and reported feeling lower control over food cravings. Further, they consumed more energy and exhibited greater wanting for high-fat food. The inverse pattern of characteristics was observed in those exhibiting a consistently high satiety phenotype (HSP. Weak satiety responsiveness is a reliable trait identifiable using the satiety quotient. The LSP was characterised by distinct behavioural and psychological characteristics indicating a risk for overeating, compared to HSP.
Directory of Open Access Journals (Sweden)
Rejas Javier
2011-06-01
Full Text Available Abstract Background Fibromyalgia (FM is a complex syndrome that affects many aspects of the patients life and it is very difficult to evaluate in clinical practice. A recent study has developed the Combined Index of Severity of Fibromyalgia (ICAF, an instrument that evaluates diverse aspects of FM and offers five indices: emotional, physical, active coping, passive coping and total. The objective of this study is to confirm the structure of the ICAF, check its test-retest reliability, assess its sensitivity to change, and compare the results obtained in a sample of patients with fibromyalgia with another sample of healthy controls. Methods A total of 232 patients took part in the study, 228 women and 4 men, with a mean age of 47.73 years of age (SD = 8.61 and a time of disease evolution since diagnosis of 4.28 years (SD = 4.03. The patients from the FM group completed the ICAF. Between one and two weeks later, they again attended the clinic and complete the 59 items on the ICAF (retest and immediately afterwards they began treatment (according to daily clinical practice criteria. A sample of healthy subjects was also studied as a control group: 110 people were included (106 women and 4 men with a mean age of 46.01 years of age (SD = 9.35. The study was conducted in Spain. Results The results obtained suggest that the four-factor model obtained in the previous study adequately fits the data obtained in this study. The test-retest reliability and internal consistency were all significant and show a high degree of correlation for all the factors as well as in overall score. With the exception of the passive coping factor, all the other scores, including the overall score, were sensitive to change after the therapeutic intervention. The ICAF scores of the patients with fibromyalgia compared with those of the control group were markedly different. Conclusions The findings suggest that the ICAF is a valid, reliable, sensitive to change instrument with
2011-01-01
Background Fibromyalgia (FM) is a complex syndrome that affects many aspects of the patients life and it is very difficult to evaluate in clinical practice. A recent study has developed the Combined Index of Severity of Fibromyalgia (ICAF), an instrument that evaluates diverse aspects of FM and offers five indices: emotional, physical, active coping, passive coping and total. The objective of this study is to confirm the structure of the ICAF, check its test-retest reliability, assess its sensitivity to change, and compare the results obtained in a sample of patients with fibromyalgia with another sample of healthy controls. Methods A total of 232 patients took part in the study, 228 women and 4 men, with a mean age of 47.73 years of age (SD = 8.61) and a time of disease evolution since diagnosis of 4.28 years (SD = 4.03). The patients from the FM group completed the ICAF. Between one and two weeks later, they again attended the clinic and complete the 59 items on the ICAF (retest) and immediately afterwards they began treatment (according to daily clinical practice criteria). A sample of healthy subjects was also studied as a control group: 110 people were included (106 women and 4 men) with a mean age of 46.01 years of age (SD = 9.35). The study was conducted in Spain. Results The results obtained suggest that the four-factor model obtained in the previous study adequately fits the data obtained in this study. The test-retest reliability and internal consistency were all significant and show a high degree of correlation for all the factors as well as in overall score. With the exception of the passive coping factor, all the other scores, including the overall score, were sensitive to change after the therapeutic intervention. The ICAF scores of the patients with fibromyalgia compared with those of the control group were markedly different. Conclusions The findings suggest that the ICAF is a valid, reliable, sensitive to change instrument with the added advantage
International Nuclear Information System (INIS)
Bauer, J.; Schueller, G.I.
1977-01-01
The first part of the analysis is concerned with the determination of the failure probability of the steel hull under internal load conditions. Two independent failure criteria are the basis for this calculation; the first one being the ultimate yield which is actually an instability condition and the second one being the fracture condition as described in Part II of the paper. Both the global and the local failure probabilities are investigated. The second part of the analysis is concerned with the external load case of earthquake. As it has already been described in Part I the probability of occurrence of a LOCA, given an earthquake has been considered in connection with the probable damage which the steel hull might experience during the earthquake. In other words the survival probability of the hull with deteriorated resistance is calculated, taking into account the frequencies of occurrence of the various events. The third part of the analysis is concerned with the reliability determination of the reinforced concrete dome structure, which is supposed to protect, the steel hull against external load conditions such as airplane crash and external pressure waves (the latter covering the load case of tornado occurrence). The reliability analysis of the reinforced concrete structure under earthquake loading is performed by utilizing the time-history method. Some aspects of the drawbacks of the response spectra method -when used in a risk analysis- are pointed out. The probability distribution of the concrete strength as determined under intermediate strain rate as described in Part II is utilized in the analysis. Finally the remaining two external load cases are discussed in light of their use in a reliability analysis and with respect to their frequency of occurrence and the probability distribution of their load intensities. The reliability demonstration is performed using the containment structure of the PWR-plant 'Biblis B' which is locate
Stavitski, N.; Klootwijk, J.H.; van Zeijl, H.W.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.
2008-01-01
The parasitic factors that strongly influence the measurement accuracy of Cross-Bridge Kelvin Resistor (CBKR) structures for low specific contact resistances (�?c) have been extensively discussed during last few decades and the minimum of the �?c value, which could be accurately extracted, was
Energy Technology Data Exchange (ETDEWEB)
Emery, John M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Coffin, Peter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robbins, Brian A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carroll, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Field, Richard V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jeremy Yoo, Yung Suk [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kacher, Josh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-09-01
Microstructural variabilities are among the predominant sources of uncertainty in structural performance and reliability. We seek to develop efficient algorithms for multiscale calcu- lations for polycrystalline alloys such as aluminum alloy 6061-T6 in environments where ductile fracture is the dominant failure mode. Our approach employs concurrent multiscale methods, but does not focus on their development. They are a necessary but not sufficient ingredient to multiscale reliability predictions. We have focused on how to efficiently use concurrent models for forward propagation because practical applications cannot include fine-scale details throughout the problem domain due to exorbitant computational demand. Our approach begins with a low-fidelity prediction at the engineering scale that is sub- sequently refined with multiscale simulation. The results presented in this report focus on plasticity and damage at the meso-scale, efforts to expedite Monte Carlo simulation with mi- crostructural considerations, modeling aspects regarding geometric representation of grains and second-phase particles, and contrasting algorithms for scale coupling.
Factor structure of internet addiction test for students in senior grades of elementary school
Directory of Open Access Journals (Sweden)
Popović-Ćitić Branislava
2013-01-01
Full Text Available One of the actual issues in the field of Internet use disorders is related to the validity and reliability of measurement instruments. The aim of this study was to examine, on non-clinical population of younger adolescents, the factor structure of the Internet Addiction Test - IAT, as one of the oldest and most widely used instruments in this field. The sample consisted of 814 Belgrade elementary school students, from fifth to eighth grade, with the average age of 12.9 years. Using exploratory factor analysis, two factors were extracted, together accounting for 46.32% of the total variance. The first factor, which accounted for 38.47% of the total variance, appeared to measure inability to control Internet use and consequences that arise as a result of excessive Internet use, while the second factor accounted for 7.85% of the variance and appeared to measure preoccupation to the Internet, responses to deprivation and replacement of real to virtual social relationships. The reliability of the whole scale, expressed by Cronbach alpha coefficient of internal consistency, was 0.91. High reliability coefficients are retained on the subscale that represent the factor, so coefficient of reliability for the first scale was 0.87, and 0.85 for the second. These findings were discussed in the context of possible modifications of the instrument and compared with the results of international research studies testing the validity and reliability of the IAT in specific national samples.
DEFF Research Database (Denmark)
Nielsen, Søren R. K.; Peng, Yongbo; Sichani, Mahdi Teimouri
2016-01-01
The paper deals with the response and reliability analysis of hysteretic or geometric nonlinear uncertain dynamical systems of arbitrary dimensionality driven by stochastic processes. The approach is based on the probability density evolution method proposed by Li and Chen (Stochastic dynamics...... of structures, 1st edn. Wiley, London, 2009; Probab Eng Mech 20(1):33–44, 2005), which circumvents the dimensional curse of traditional methods for the determination of non-stationary probability densities based on Markov process assumptions and the numerical solution of the related Fokker–Planck and Kolmogorov......–Feller equations. The main obstacle of the method is that a multi-dimensional convolution integral needs to be carried out over the sample space of a set of basic random variables, for which reason the number of these need to be relatively low. In order to handle this problem an approach is suggested, which...
International Nuclear Information System (INIS)
Maurer, H.A.
1978-01-01
The interest shown in the general prospects of primary energy in European countries prompted description of the actual European situation. Explanation of the needs for installation of nuclear power plants in most contries of the European Communities are given. Activities of the Commission of the European Communities to initiate a progressive harmonization of already existing European criteria, codes and complementary requirements in order to improve the structural reliability of components and systems of nuclear power plants are summarized. Finally, the applicability of a probabilistic safety analysis to facilitate decision-making as to safety by defining acceptable target and limit values, coupled with a subjective estimate as it is applied in the safety analyses performed in most European countries, is demonstrated. (Auth.)
Stress analysis of R2 pressure vessel. Structural reliability benchmark exercise
International Nuclear Information System (INIS)
Vestergaard, N.
1987-05-01
The Structural Reliability Benchmark Exercise (SRBE) is sponsored by the EEC as part of the Reactor Safety Programme. The objectives of the SRBE are to evaluate and improve 1) inspection procedures, which use non-destructive methods to locate defects in pressure (reactor) vessels, as well as 2) analytical damage accumulation models, which predict the time to failure of vessels containing defects. In order to focus attention, an experimental presure vessel has been inspected, subjected fatigue loadings and subsequently analysed by several teams using methods of their choice. The present report contains the first part of the analytical damage accumulation analysis. The stress distributions in the welds of the experimental pressure vessel were determined. These stress distributions will be used to determine the driving forces of the damage accumulation models, which will be addressed in a future report. (author)
A structural approach to constructing perspective efficient and reliable human-computer interfaces
International Nuclear Information System (INIS)
Balint, L.
1989-01-01
The principles of human-computer interface (HCI) realizations are investigated with the aim of getting closer to a general framework and thus, to a more or less solid background of constructing perspective efficient, reliable and cost-effective human-computer interfaces. On the basis of characterizing and classifying the different HCI solutions, the fundamental problems of interface construction are pointed out especially with respect to human error occurrence possibilities. The evolution of HCI realizations is illustrated by summarizing the main properties of past, present and foreseeable future interface generations. HCI modeling is pointed out to be a crucial problem in theoretical and practical investigations. Suggestions concerning HCI structure (hierarchy and modularity), HCI functional dynamics (mapping from input to output information), minimization of human error caused system failures (error-tolerance, error-recovery and error-correcting) as well as cost-effective HCI design and realization methodology (universal and application-oriented vs. application-specific solutions) are presented. The concept of RISC-based and SCAMP-type HCI components is introduced with the aim of having a reduced interaction scheme in communication and a well defined architecture in HCI components' internal structure. HCI efficiency and reliability are dealt with, by taking into account complexity and flexibility. The application of fast computerized prototyping is also briefly investigated as an experimental device of achieving simple, parametrized, invariant HCI models. Finally, a concise outline of an approach of how to construct ideal HCI's is also suggested by emphasizing the open questions and the need of future work related to the proposals, as well. (author). 14 refs, 6 figs
Energy Technology Data Exchange (ETDEWEB)
Jung, Won Dea; Kim, Jae Whan; Park, Jin Kyun; Ha, Jae Joo [Korea Atomic Energy Research Institute, Taejeon (Korea)
2000-02-01
More than twenty HRA (Human Reliability Analysis) methodologies have been developed and used for the safety analysis in nuclear field during the past two decades. However, no methodology appears to have universally been accepted, as various limitations have been raised for more widely used ones. One of the most important limitations of conventional HRA is insufficient analysis of the task structure and problem space. To resolve this problem, we suggest SIA (Structured Information Analysis) for HRA. The proposed SIA consists of three parts. The first part is the scenario analysis that investigates the contextual information related to the given task on the basis of selected scenarios. The second is the goals-means analysis to define the relations between the cognitive goal and task steps. The third is the cognitive function analysis module that identifies the cognitive patterns and information flows involved in the task. Through the three-part analysis, systematic investigation is made possible from the macroscopic information on the tasks to the microscopic information on the specific cognitive processes. It is expected that analysts can attain a structured set of information that helps to predict the types and possibility of human error in the given task. 48 refs., 12 figs., 11 tabs. (Author)
Ensuring Reliability of Reinforced Concrete Structures of “Northern Installation”
Pinus, B. I.; Pinus, Zh N.
2017-11-01
One of the directions in active management of the building structures design reliability is the correction of functional models of the criterial efficiency based on the specific conditions of their operation. With respect to the reinforced concrete structures of the “northern installation”, such an approach predetermines the necessity to consider kinetics and statistical patterns of wear under systemic and cyclical impacts of low negative temperatures and humidity. Concurrently, the task of project assurance of equitability with usual structures of the “northern installation” for the duration of the expected service life is considered. In the first approximation, this task is proposed to be solved by correcting significant parameters of the concrete’s constructive properties in correlation with the kinetics of exhaustion of the concrete’s projected (controlled) frost resistance. This work presents the results of statistically representative generalization of the change in strength, modulus of elasticity and ultimate deformations in cryogenic and thawed states under cyclic impact of temperatures up to minus 40°C. Based on these results, the dynamic models of dependency of concrete’s standardized characteristics on its frost’s resistance exhaustion level have been developed.
Wrist and Hand Ultrasound: Reliability of Side-to-Side Comparisons of Very Small (Structures.
Rossi, Federica; Romano, Nicola; Muda, Alessandro; Martinoli, Carlo; Tagliafico, Alberto
2018-04-24
In ultrasound (US) examinations of clinically relevant very small structures of the wrist and hand, the healthy contralateral side can be used as a reference to identify subtle abnormalities. Intraindividual side-to-side variability must be minimal. The aim of this study was to assess the reliability of side-to-side US evaluations of very small structures of the wrist and hand. Forty-one healthy volunteers were prospectively studied. Small structures of the wrist and hand were evaluated bilaterally by 2 musculoskeletal radiologists in separate sessions. The first annular pulleys of the second finger and the thumb, sagittal band of the third finger, extensor and flexor retinacula, ulnar collateral ligament of the thumb, radial collateral ligament of the second finger, and palmar cutaneous branches of the median and ulnar nerves were considered. To assess intra- and inter-reader agreement, 10 of 41 (24%) examinations were repeated. Nonparametric statistics were used. Data were not normally distributed (P > .001). Intra-reader agreement was κ = 0.674 (95% confidence interval [CI], 0.57-0.78), and inter-reader agreement was κ = 0.935 (95% CI, 0.92-0.95). The mean value ± SD for all of the structures was 0.78 ± 0.44 mm. The overall coefficient of variation was 9.8% ± 0.07%. The intraclass correlation coefficient was 0.97 (95% CI, 0.96-0.98). In clinical practice, the healthy contralateral side can be used as a reference during a real-time musculoskeletal US evaluation of small (structures. © 2018 by the American Institute of Ultrasound in Medicine.
Zhang, Huiping; Yip, Paul S. F.; Chi, Peilian; Chan, Kinsun; Cheung, Yee Tak; Zhang, Xiulan
2012-01-01
The purpose of this study was to explore the factor structure of the Work-Family Balance Scale (WFBS) and examine its reliability and validity in use in the urban Chinese population. The scale was validated using a sample of 605 urban Chinese residents from 7 cities. Exploratory factor analysis identified two factors: work-family conflict and…
DEFF Research Database (Denmark)
Petersen, Kurt Erling
1986-01-01
Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety...... and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic...... approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very...
International Nuclear Information System (INIS)
Schnurer, H.
1980-01-01
The methods of structural reliability, knowing their benefits and their limitations, will offer an increasingly important tool in order to make future quality decisions for nuclear safety more rational, objective and balanced. This might make them suitable for licensing and approval decisions of components and structures, offering an alternative to the presently used deterministic practice. (orig./RW)
DEFF Research Database (Denmark)
Isaksen, Jesper; Hertel, Niels Thomas; Kjær, Niels Kristian
2013-01-01
In order to optimise the selection process for admission to specialist training in family medicine, we developed a new design for structured applications and selection interviews. The design contains semi-structured interviews, which combine individualised elements from the applications...... with standardised behaviour-based questions. This paper describes the design of the tool, and offers reflections concerning its acceptability, reliability and feasibility....
Correlation Relationship of Performance Shaping Factors (PSFs) for Human Reliability Analysis
Energy Technology Data Exchange (ETDEWEB)
Bheka, M. Khumalo; Kim, Jonghyun [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)
2014-10-15
At TMI-2, operators permitted thousands of gallons of water to escape from the reactor plant before realizing that the coolant pumps were behaving abnormally. The coolant pumps were then turned off, which in turn led to the destruction of the reactor itself as cooling was completely lost within the core. Human also plays a role in many aspects of complex systems e.g. in design and manufacture of hardware, interface between human and system and also in maintaining such systems as well as for coping with unusual events that place the NPP system at a risk. This is why human reliability analysis (HRA) - an aspect of risk assessments which systematically identifies and analyzes the causes and consequences of human decisions and actions - is important in nuclear power plant operations. It either upgrades or degrades human performance; therefore it has an impact on the possibility of error. These PSFs can be used in various HRA methods to estimate Human Error Probabilities (HEPs). There are many current HRA methods who propose sets of PSFs for normal operation mode of NPP. Some of these PSFs in the sets have some degree of dependency and overlap. Overlapping PSFs introduce error in HEP evaluations due to the fact that some elements are counted more than once in data; this skews the relationship amongst PSF and masks the way that the elements interact to affect performance. This study uses a causal model that represents dependencies and relationships amongst PSFs for HEP evaluation during normal NPP operational states. The model is built taking into consideration the dependencies among PSFs and thus eliminating overlap. The use of an interdependent model of PSFs is expected to produce more accurate HEPs compared to other current methods. PSF sets produced in this study can be further used as nodes (variables) and directed arcs (causal influence between nodes) in HEP evaluation methods such as Bayesian belief (BN) networks. This study was done to estimate the relationships
Maiano, Christophe; Morin, Alexandre J. S.; Begarie, Jerome
2011-01-01
The purpose of this study was to test the factor validity and reliability of the Center for Epidemiologic Studies Depression Scale (CES-D) within a sample of adolescents with mild to moderate Intellectual Disability (ID). A total sample of 189 adolescents (121 boys and 68 girls), aged between 12 and 18 years old, with mild to moderate ID were…
DEFF Research Database (Denmark)
Hougs Kjær, Birgitte; Ellegaard, Karen; Wieland, Ina
2017-01-01
BACKGROUND: US-examinations related to shoulder impingement (SI) often vary due to methodological differences, examiner positions, transducers, and recording parameters. Reliable US protocols for examination of different structures related to shoulder impingement are therefore needed. OBJECTIVES...... of the supraspinatus tendon (SUPRA) and subacromial subdeltoid (SASD) bursa in two imaging positions, and the acromial humeral distance (AHD) in one position. Additionally, agreement on dynamic impingement (DI) examination was performed. The intra- and inter-rater reliability was carried out on the same day...
International Nuclear Information System (INIS)
Baek, Kyunghyun; Jang, Kyungsoo; Lee, Youn-Jung; Ryu, Kyungyul; Choi, Woojin; Kim, Doyoung; Yi, Junsin
2013-01-01
We report the effect of silver (Ag)-buffer layer Indium-Tin-Oxide (ITO) film on a polyethylene terephthalate substrate on the electrical, optical and reliable properties for transparent–flexible displays. The electrical and optical characteristics of an ITO-only film and an Ag-layer-inserted ITO film are measured and compared to assess the applicability of the triple layered structure in flexible displays. The sheet resistance, the resistivity and the light transmittance of the ITO-only film were 400 Ω/sq, 1.33 × 10 −3 Ω-cm and 99.2%, while those of the ITO film inserted with a 10 nm thick Ag layer were 165 Ω/sq, 4.78 × 10 −4 Ω-cm and about 97%, respectively. To evaluate the mechanical reliability of the different ITO films, bending tests were carried out. After the dynamic bending test of 900 cycles, the sheet resistance of the ITO film inserted with the Ag layer changed from 154 Ω/sq to 475 Ω/sq, about a 3-time increase but that of the ITO-only film changed from 400 Ω/sq to 61,986 Ω/sq, about 150-time increase. When the radius is changed from 25 mm to 20 mm in the static bending test, the sheet resistance of the ITO-only film changed from 400 to 678.3 linearly whereas that of the Ag-layer inserted ITO film changed a little from 154.4 to 154.9. These results show that Ag-layer inserted ITO film had better mechanical characteristics than the ITO-only film. - Highlights: ► Transparent flexible electrode fabricated on glass substrate. ► Electrode fabricated using vertically-patterned design on glass substrate. ► Optimization of the vertical patterns ► Application of the vertically-patterned electrode in transparent–flexible electronics
Chahoud, M; Chahine, R; Salameh, P; Sauleau, E A
2017-06-01
Our goal is to validate and to verify the reliability of the French and English versions of the Insomnia Severity Index (ISI) in Lebanese adolescents. A cross-sectional study was implemented. 104 Lebanese students aged between 14 and 19 years participated in the study. The English version of the questionnaire was distributed to English-speaking students and the French version was administered to French-speaking students. A scale (1 to 7 with 1 = very well understood and 7 = not at all) was used to identify the level of the students' understanding of each instruction, question and answer of the ISI. The scale's structural validity was assessed. The factor structure of ISI was evaluated by principal component analysis. The internal consistency of this scale was evaluated by Cronbach's alpha. To assess test-retest reliability the intraclass correlation coefficient (ICC) was used. The principal component analysis confirmed the presence of a two-component factor structure in the English version and a three-component factor structure in the French version with eigenvalues > 1. The English version of the ISI had an excellent internal consistency (α = 0.90), while the French version had a good internal consistency (α = 0.70). The ICC presented an excellent agreement in the French version (ICC = 0.914, CI = 0.856-0.949) and a good agreement in the English one (ICC = 0.762, CI = 0.481-890). The Bland-Altman plots of the two versions of the ISI showed that the responses over two weeks' were comparable and very few outliers were detected. The results of our analyses reveal that both English and French versions of the ISI scale have good internal consistency and are reproducible and reliable. Therefore, it can be used to assess the prevalence of insomnia in Lebanese adolescents.
James, C P; Harburn, K L; Kramer, J F
1997-08-01
This study addresses test-retest reliability of the Postural and Repetitive Risk-Factors Index (PRRI) for work-related upper body injuries. This assessment was developed by the present authors. A repeated measures design was used to assess the test-retest reliability of a videotaped work-site assessment of subjects' movements. Ten heavy users of video display terminals (VDTs) from a local banking industry participated in the study. The 10 subjects' movements were videotaped for 2 hours on each of 2 separate days, while working on-site at their VDTs. The videotaped assessment, which utilized known postural risk factors for developing musculoskeletal disorder, pain, and discomfort in heavy VDT users (ie, repetitiveness, awkward and static postures, and contraction time), was called the PRRI. The videotaped movement assessments were subsequently analyzed in 15-minute sessions (five sessions per 2-hour videotape, which produced a total of 10 sessions over the 2 testing days), and each session was chosen randomly from the videotape. The subjects' movements were given a postural risk score according to the criteria in the PRRI. Each subject was therefore tested a total of 10 times (ie, 10 sessions), over two days. The maximum PRRI score for both sides of the body was 216 points. Reliability coefficients (RCs) for the PRRI scores were calculated, and the reliability of any one session met the minimum criterion for excellent reliability, which was .75. A two-way analysis of variance (ANOVA) confirmed that there was no statistically significant difference between sessions (p < .05). Calculations using the standard error of measurement (SEM) indicated that an individual tested once, on one day and with a PRRI score of 25, required a change of at least 8 points in order to be confident that a true change in score had occurred. The significant results from the reliability tests indicated that the PRRI was a reliable measurement tool that could be used by occupational health
Reedy, Gabriel B; Lavelle, Mary; Simpson, Thomas; Anderson, Janet E
2017-10-01
A central feature of clinical simulation training is human factors skills, providing staff with the social and cognitive skills to cope with demanding clinical situations. Although these skills are critical to safe patient care, assessing their learning is challenging. This study aimed to develop, pilot and evaluate a valid and reliable structured instrument to assess human factors skills, which can be used pre- and post-simulation training, and is relevant across a range of healthcare professions. Through consultation with a multi-professional expert group, we developed and piloted a 39-item survey with 272 healthcare professionals attending training courses across two large simulation centres in London, one specialising in acute care and one in mental health, both serving healthcare professionals working across acute and community settings. Following psychometric evaluation, the final 12-item instrument was evaluated with a second sample of 711 trainees. Exploratory factor analysis revealed a 12-item, one-factor solution with good internal consistency (α=0.92). The instrument had discriminant validity, with newly qualified trainees scoring significantly lower than experienced trainees ( t (98)=4.88, pSkills for Healthcare Instrument provides a reliable and valid method of assessing trainees' human factors skills self-efficacy across acute and mental health settings. This instrument has the potential to improve the assessment and evaluation of human factors skills learning in both uniprofessional and interprofessional clinical simulation training.
Reliability-based assessment of deteriorating ship-shaped offshore structures
Energy Technology Data Exchange (ETDEWEB)
Ayala-Uraga, Efren
2009-11-15
components rises accordingly. Therefore, it is indispensable for FPSO operators to assess the safety of existing vessels with proper consideration of the uncertainties involved. The aim of this dissertation is to discuss the safety assessment of an existing shipshaped offshore structure subjected to deterioration, where the interaction among different deteriorating phenomena such as fatigue, corrosion and fracture, are explicitly accounted for in a systematic and consistent manner. The format of this thesis report consists of an extended summary intended to emphasize the main contributions achieved and the relevant issues dealt with during this research work, which resulted in the production of three articles that have already been published, annexed at the end of the report. The first article, referred to as Article 1 throughout this report, was published in the International Journal of Fatigue (2007). This article deals with the treatment of uncertainties related to the fatigue crack growth of surface cracks on plated connections and compares different reliability-based limit state formulations including a bi-linear crack growth law that is recommended by the British Standard BS-7910 (1999). Calibration of the bi-linear fracture mechanics formulation is performed with respect to design SN curves considering the parameters with largest uncertainties. The second article, Article 2, published in Reliability Engineering and System Safety (2008) describes a procedure based on reliability techniques to assess the safety level on a welded connection of an aging FPSO with respect fatigue failure, taking into account in the crack growth estimation the effect of the vessel being exposed to various climate conditions throughout the service life. This means that the fatigue damage accumulated under previous operational conditions of the vessel, e.g. as tanker before conversion, is explicitly accounted for in the failure function. Thus, the uncertainties are also explicitly considered
Reliability Assessment Of Wind Turbines
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
2014-01-01
Reduction of cost of energy for wind turbines are very important in order to make wind energy competitive compared to other energy sources. Therefore the turbine components should be designed to have sufficient reliability but also not be too costly (and safe). This paper presents models...... for uncertainty modeling and reliability assessment of especially the structural components such as tower, blades, substructure and foundation. But since the function of a wind turbine is highly dependent on many electrical and mechanical components as well as a control system also reliability aspects...... of these components are discussed and it is described how there reliability influences the reliability of the structural components. Two illustrative examples are presented considering uncertainty modeling, reliability assessment and calibration of partial safety factors for structural wind turbine components exposed...
Directory of Open Access Journals (Sweden)
A.A. Pryimakov
2017-04-01
Full Text Available Purpose: to study reliability of functioning and reserves of system, controlling movements with different coordination structure of special health group girl students (low health level in physical education process. Material: in the research special health group girl students (n=136, age 17-19 participated. They were divided into 2 groups - control and experimental. The program, directed to increase reliability and reserves of system controlling movements, was realized. It was based on physical exercises of complicated coordination with novelty elements, which were fulfilled under musical accompaniment. The research continued one academic year. Results: in girl students with health problems we registered higher differential thresholds, when reproducing local movements in complicated conditions. They used visual and hearing feedback channels for informing brain’s programming areas about made mistakes. They were worse teachable in training accurate movements. These girl students have less expressed compensation reserves under impact of hindering factors and interferences. It can be interpreted as non-specific crisscross negative response to motor functional system in case of health problems. All these determine reduction of reserve potentials of motor control system. Conclusions: The main reserve potentials’ criteria of control over different coordination structure movements are: quickness of passing to program mechanism of fine movements’ regulation in stable conditions of functioning; power and effectiveness of compensatory reactions, ensuring interference immunity of system, controlling movements under interfering factors; reliability of maintaining movements’ qualitative parameters in optimal range under interfering factors; reduction of sensor interconnections in stable functioning conditions.
International Nuclear Information System (INIS)
Kozak, M.; Havel, S.
1989-09-01
In Czechoslovakia, there are eight WWER 440 type reactors in operation at present. Since their introduction into operation, nuclear power plants in Czechoslovakia have exhibited high reliability. In the paper, total parameters of reliability with an analysis of causes affecting negatively their annual utilization are presented. Existence of a computerized information system for acquisition, recording and evaluation of reliability-significant data from operation and its feedback to designers and manufacturers of nuclear power plant equipment and components is a basic requirement of a systematic assurance of the needed level of nuclear power plant reliability. The information system is used simultaneously also for realistic evaluation of aging of equipment and systems. Analysis of the state of equipment is important mainly in the final stage of the NPP during consideration of further extension of its service life. Environmental effects of the Czechoslovak NPPs are very low (favourable). It follows from comparison of annual dose equivalents of the Czechoslovak NPPs operational personnel with the foreign NPPs that the values recorded in Czechoslovakia belong to the lowest ones. In conclusion, some ways of assurance of operational safety and reliability of the Czechoslovak nuclear power plants including the role of the State regulatory body are briefly discussed. (author). 3 tabs
Optimal Reliability-Based Code Calibration
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard; Kroon, I. B.; Faber, Michael Havbro
1994-01-01
Calibration of partial safety factors is considered in general, including classes of structures where no code exists beforehand. The partial safety factors are determined such that the difference between the reliability for the different structures in the class considered and a target reliability...... level is minimized. Code calibration on a decision theoretical basis is also considered and it is shown how target reliability indices can be calibrated. Results from code calibration for rubble mound breakwater designs are shown....
International Nuclear Information System (INIS)
Ryan, T.G.
1988-01-01
This paper describes an emerging Task Analysis-Linked Evaluation Technique (TALENT) for assessing the contributions of human error to nuclear power plant systems unreliability and risk. Techniques such as TALENT are emerging as a recognition that human error is a primary contributor to plant safety, however, it has been a peripheral consideration to data in plant reliability evaluations. TALENT also recognizes that involvement of persons with behavioral science expertise is required to support plant reliability and risk analyses. A number of state-of-knowledge human reliability analysis tools are also discussed which support the TALENT process. The core of TALENT is comprised of task, timeline and interface analysis data which provide the technology base for event and fault tree development, serve as criteria for selecting and evaluating performance shaping factors, and which provide a basis for auditing TALENT results. Finally, programs and case studies used to refine the TALENT process are described along with future research needs in the area. (author)
DEFF Research Database (Denmark)
Bruyn, George Aw; Naredo, Esperanza; Damjanov, Nemanja
2016-01-01
OBJECTIVE: To assess whether ultrasonography (US) is reliable for the evaluation of inflammatory and structural abnormalities in patients with knee osteoarthritis (OA). METHODS: Thirteen patients with early knee OA were examined by 11 experienced sonographers during 2 days. Dichotomous and semiqu......OBJECTIVE: To assess whether ultrasonography (US) is reliable for the evaluation of inflammatory and structural abnormalities in patients with knee osteoarthritis (OA). METHODS: Thirteen patients with early knee OA were examined by 11 experienced sonographers during 2 days. Dichotomous...
Energy Technology Data Exchange (ETDEWEB)
Stavrakakis, G.; Lucia, A.C.; Solomos, G. (Commission of the European Communities, Ispra (Italy). Joint Research Centre)
1990-01-01
The two computer codes COVASTOL and RELIEF, developed for the modeling of cumulative damage processes in the framework of probabilistic structural reliability, are compared. They are based respectively on the randomisation of a differential crack growth law and on the theory of discrete Markov processes. The codes are applied for fatigue crack growth predictions using two sets of data of crack propagation curves from specimens. The results are critically analyzed and an extensive discussion follows on the merits and limitations of each code. Their transferability for the reliability assessment of real structures is investigated. (author).
STRUCTURAL FLUCTUATIONS, ELECTRICAL RESPONSE AND THE RELIABILITY OF NANOSTRUCTURES (FINAL REPORT)
Energy Technology Data Exchange (ETDEWEB)
Philip J. Rous; Ellen D. Williams; Michael S. Fuhrer
2006-07-31
The goal of the research supported by DOE-FG02-01ER45939 was to synthesize a number of experimental and theoretical approaches to understand the relationship between morphological fluctuations, the electrical response and the reliability (failure) of metallic nanostructures. The primary focus of our work was the study of metallic nanowires which we regard as prototypical of nanoscale interconnects. Our research plan has been to link together these materials properties and behaviors by understanding the phenomenon of, and the effects of electromigration at nanometer length scales. The thrust of our research has been founded on the concept that, for nanostructures where the surface-to-volume ratio is necessarily high, surface diffusion is the dominant mass transport mechanism that governs the fluctuations, electrical properties and failure modes of nanostructures. Our approach has been to develop experimental methods that permit the direct imaging of the electromagnetic distributions within nanostructures, their structural fluctuations and their electrical response. This experimental research is complemented by a parallel theoretical and computational program that describes the temporal evolution of nanostructures in response to current flow.
International Nuclear Information System (INIS)
Sturm, R.
1991-01-01
Two aspects of performance are of main concern: plant availability and plant reliability (defined as the conditional probability of an unplanned shutdown). The goal of the research is a unified framework that combines behavioral models of optimizing agents with models of complex technical systems that take into account the dynamic and stochastic features of the system. In order to achieve this synthesis, two liens of work are necessary. One line requires a deeper understanding of complex production systems and the type of data they give rise to; the other line involves the specification and estimation of a rigorously specified behavioral model. Plant operations are modeled as a controlled stochastic process, and the sequence of up and downtime spells is analyzed during failure time and point process models. Similar to work on rational expectations and structural econometric models, the behavior model of how the plant process is controlled is formulated at the level of basic processes, i.e., the objective function of the plant manager, technical constraints, and stochastic disturbances
Effects of strain history on structural reliability analysis of pipes subjected to reeling
Energy Technology Data Exchange (ETDEWEB)
Ernst, Hugo A.; Bravo, Richard E. [TENARIS Group, Campana (Argentina). Center for Industrial Research; Daguerre, Federico [TENARIS Group (Mexico). TAMSA
2005-07-01
In this work a method to perform a Structural Reliability Analysis (SRA) for a tube subject to reeling is considered in detail. A fracture mechanics based methodology is reviewed and the points that need to be resolved before extending the methods to include reeling are clearly identified. The effect of the strain history on the applied and material fracture mechanics parameters were studied. A theoretical model was developed to describe the crack driving force evolution through strain cycles. A criterion was proposed and corroborated to represent material fracture resistance behavior. An experimental program was carried out. The material analyzed was a X65 grade. Monotonic and cyclic fracture mechanic tests were performed on single edge notch in tension specimens. The material fracture resistance curve was determined based on the monotonic tests. The cyclic tests were used to determine experimentally the applied fracture mechanic parameters evolution. A very good agreement between predicted and measured CTOD values was obtained for the cases analyzed. A methodology to perform a SRA for tube subjected to reeling is proposed. (author)
International Nuclear Information System (INIS)
Goel, V.S.
1985-01-01
This book presents the papers given at a conference on nuclear power plant life extension. Topics considered at the conference included availability, accelerated aging techniques, the qualification of electrical equipment, probabilistic risk assessment, reactor maintenance, outages, reliability, computer-aided design, seismic effects, mechanical vibrations, fatigue monitoring, steam generators, and materials degradation by aging and embrittlement
International Nuclear Information System (INIS)
Hall, R.E.; Fragola, J.R.; Luckas, W.J. Jr.
1981-09-01
The role of the human in the safety of nuclear power plant operations was addressed in a meeting held in Myrtle Beach, SC in August 1981. Presentation were made on Control Room reviews, safety parameter display systems, the integration of human factors in the entire design process, and the use of automated control features. A need was shown for the development of a taxonomy or model to structure future data gathering and the need for models and data to address the issue of cognitive behavior. The primary effect of this behavior on risk was identified. Discussion sessions on the human impact on reliability, and control room design and evaluation were included
Electronic structure of BN-aromatics: Choice of reliable computational tools
Mazière, Audrey; Chrostowska, Anna; Darrigan, Clovis; Dargelos, Alain; Graciaa, Alain; Chermette, Henry
2017-10-01
The importance of having reliable calculation tools to interpret and predict the electronic properties of BN-aromatics is directly linked to the growing interest for these very promising new systems in the field of materials science, biomedical research, or energy sustainability. Ionization energy (IE) is one of the most important parameters to approach the electronic structure of molecules. It can be theoretically estimated, but in order to evaluate their persistence and propose the most reliable tools for the evaluation of different electronic properties of existent or only imagined BN-containing compounds, we took as reference experimental values of ionization energies provided by ultra-violet photoelectron spectroscopy (UV-PES) in gas phase—the only technique giving access to the energy levels of filled molecular orbitals. Thus, a set of 21 aromatic molecules containing B-N bonds and B-N-B patterns has been merged for a comparison between experimental IEs obtained by UV-PES and various theoretical approaches for their estimation. Time-Dependent Density Functional Theory (TD-DFT) methods using B3LYP and long-range corrected CAM-B3LYP functionals are used, combined with the Δ SCF approach, and compared with electron propagator theory such as outer valence Green's function (OVGF, P3) and symmetry adapted cluster-configuration interaction ab initio methods. Direct Kohn-Sham estimation and "corrected" Kohn-Sham estimation are also given. The deviation between experimental and theoretical values is computed for each molecule, and a statistical study is performed over the average and the root mean square for the whole set and sub-sets of molecules. It is shown that (i) Δ SCF+TDDFT(CAM-B3LYP), OVGF, and P3 are the most efficient way for a good agreement with UV-PES values, (ii) a CAM-B3LYP range-separated hybrid functional is significantly better than B3LYP for the purpose, especially for extended conjugated systems, and (iii) the "corrected" Kohn-Sham result is a
Dogan, Tayfun; Cetin, Bayram
2009-01-01
The purpose of the present study was to investigate the reliability and validity of the Turkish version of the Tromso Social Intelligence Scale (TSIS) developed by Silvera, Martinussen, and Dahl (2001). 719 students from Sakarya University participated in the study. Construct validity and criterion related validity and reliability were assessed.…
Smith, Jack E.; Hakel, Milton D.
1979-01-01
Examined are questions pertinent to the use of the Position Analysis Questionnaire: Who can use the PAQ reliably and validly? Must one rely on trained job analysts? Can people having no direct contact with the job use the PAQ reliably and validly? Do response biases influence PAQ responses? (Author/KC)
Factor Structure of the Eating Disorder Examination Interview in Patients With Binge-eating Disorder
Grilo, Carlos M.; Crosby, Ross D.; Peterson, Carol B.; Masheb, Robin M.; White, Marney A.; Crow, Scott J.; Wonderlich, Stephen A.; Mitchell, James E.
2013-01-01
Despite the widespread use of the Eating Disorder Examination (EDE) as a primary assessment instrument in studies of eating and weight disorders, little is known about the psychometric aspects of this interview measure. The primary purpose of this study was to evaluate the factor structure of the EDE interview in a large series of patients with binge-eating disorder (BED). Participants were 688 treatment-seeking patients with BED who were reliably administered the EDE interview by trained research clinicians at three research centers. Exploratory factor analysis (EFA) performed on EDE interview data from a random split-half of the study group suggested a brief 7-item 3-factor structure. Confirmatory factor analysis (CFA) performed on the second randomly selected half of the study group supported this brief 3-factor structure of the EDE interview. The three factors were interpreted as Dietary Restraint, Shape/Weight Overvaluation, and Body Dissatisfaction. In this series of patients with BED, factor analysis of the EDE interview did not replicate the original subscales but revealed an alternative factor structure. Future research must further evaluate the psychometric properties, including the factor structure, of the EDE interview in this and other eating-disordered groups. The implications of these factor analytic findings for understanding and assessing the specific psychopathology of patients with BED are discussed. PMID:19798064
Examining the factor structure of MUIS-C scale among baby boomers with hepatitis C.
Reinoso, Humberto; Türegün, Mehmet
2016-11-01
Baby boomers account for two out of every three cases of hepatitis C infection in the U.S. To conduct an exploratory factor analysis directed at supporting the use of the MUIS-C as a reliable instrument in measuring illness uncertainty among baby boomers with hepatitis C. The steps of conducting a typical principal component analysis (PCA) with an oblique rotation were used on a sample of 146 participants, the sampling adequacy of items was examined via the Kaiser-Meyer-Olkin (KMO) measure, and the Bartlett's sphericity test was used for appropriateness of conducting a factor analysis. A two-factor structure was obtained by using Horn's parallel analysis method. The two factors explained a cumulative total of 45.8% of the variance. The results of the analyses indicated that the MUIS-C was a valid and reliable instrument and potentially suitable for use in baby boomer population diagnosed with hepatitis C. Published by Elsevier Inc.
Structure design of human factor data management system for Daya Bay NPP
International Nuclear Information System (INIS)
Zhang Li; Zhang Ning; Guo Jianbing; Huang Weigang; Zhu Minhong; Wang Jin
2000-01-01
Collection, analysis and quantification of human factor data are important compositions of human reliability analysis (HRA) and probabilistic risk assessment (PRA). Various human factor databases have been set up, but there are comparatively little human factor data management systems which can be uses for collection, classification, analysis, calculation and predication of the human factor data. Therefore, the human factor data management system for Daya Bay NPP is developed, with the following three modules and four databases: original data module, computing module, introduced data module, and basic database, other data source of the plant, external database and introduced database. The foundational problems about human factor data and the systemic structure and function are described. The data structure in the database is also discussed, because it is of the most importance in the system
Sarti, E.; Zamuner, S.; Cossio, P.; Laio, A.; Seno, F.; Trovato, A.
2013-12-01
In protein structure prediction it is of crucial importance, especially at the refinement stage, to score efficiently large sets of models by selecting the ones that are closest to the native state. We here present a new computational tool, BACHSCORE, that allows its users to rank different structural models of the same protein according to their quality, evaluated by using the BACH++ (Bayesian Analysis Conformation Hunt) scoring function. The original BACH statistical potential was already shown to discriminate with very good reliability the protein native state in large sets of misfolded models of the same protein. BACH++ features a novel upgrade in the solvation potential of the scoring function, now computed by adapting the LCPO (Linear Combination of Pairwise Orbitals) algorithm. This change further enhances the already good performance of the scoring function. BACHSCORE can be accessed directly through the web server: bachserver.pd.infn.it. Catalogue identifier: AEQD_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEQD_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 3 No. of lines in distributed program, including test data, etc.: 130159 No. of bytes in distributed program, including test data, etc.: 24 687 455 Distribution format: tar.gz Programming language: C++. Computer: Any computer capable of running an executable produced by a g++ compiler (4.6.3 version). Operating system: Linux, Unix OS-es. RAM: 1 073 741 824 bytes Classification: 3. Nature of problem: Evaluate the quality of a protein structural model, taking into account the possible “a priori” knowledge of a reference primary sequence that may be different from the amino-acid sequence of the model; the native protein structure should be recognized as the best model. Solution method: The contact potential scores the occurrence of any given type of residue pair in 5 possible
Đorđević Vesna; Savić Marko; Vasilev Saša; Đorđević Milovan
2013-01-01
On the basis of the performed analyses of the factors that contributed the infected meat reach food chain, we have found out that the infection occurred after consuming the meat inspected by the method of collective samples artificial digestion by using a magnetic stirrer (MM). In this work there are presented assay results which show how modifications of the method, on the level of final sedimentation, influence the reliability of Trichinella larvas detect...
[Tolerance for frustration as a reliability factor in the work of the human operator].
Makarevich, O F
1986-01-01
Frustration tolerance is a personality trait that contributes to the reliable performance of an air traffic controller. This paper presents the results of a psychological examination of air traffic controllers using the Rosenzweig frustration test and emphasizes a correlation between the predominant behavior type in frustrating circumstances and professional success. The paper contains examples of realistic observations over air traffic controllers which confirm experimental data.
Bao, Han P.
1995-01-01
Fabricating primary aircraft and spacecraft structures using advanced composite materials entail both benefits and risks. The benefits come from much improved strength-to-weight ratios and stiffness-to-weight ratios, potential for less part count, ability to tailor properties, chemical and solvent resistance, and superior thermal properties. On the other hand, the risks involved include high material costs, lack of processing experience, expensive labor, poor reproducibility, high toxicity for some composites, and a variety of space induced risks. The purpose of this project is to generate a manufacturing database for a selected number of materials with potential for space applications, and to rely on this database to develop quantitative approaches to screen candidate materials and processes for space applications on the basis of their manufacturing risks including costs. So far, the following materials have been included in the database: epoxies, polycyanates, bismalemides, PMR-15, polyphenylene sulfides, polyetherimides, polyetheretherketone, and aluminum lithium. The first four materials are thermoset composites; the next three are thermoplastic composites, and the last one is is a metal. The emphasis of this database is on factors affecting manufacturing such as cost of raw material, handling aspects which include working life and shelf life of resins, process temperature, chemical/solvent resistance, moisture resistance, damage tolerance, toxicity, outgassing, thermal cycling, and void content, nature or type of process, associate tooling, and in-process quality assurance. Based on industry experience and published literature, a relative ranking was established for each of the factors affecting manufacturing as listed above. Potential applications of this database include the determination of a delta cost factor for specific structures with a given process plan and a general methodology to screen materials and processes for incorporation into the current
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
2011-01-01
Reliability-based cost-optimal planning of inspection, maintenance and operation has many applications. In this paper applications for planning of inspections for oil & gas jacket structures and of operation and maintenance of offshore wind turbines are described and illustrated by examples....
Trapsilawati, Fitri; Qu, Xingda; Wickens, Chris D; Chen, Chun-Hsien
2015-01-01
Though it has been reported that air traffic controllers' (ATCos') performance improves with the aid of a conflict resolution aid (CRA), the effects of imperfect automation on CRA are so far unknown. The main objective of this study was to examine the effects of imperfect automation on conflict resolution. Twelve students with ATC knowledge were instructed to complete ATC tasks in four CRA conditions including reliable, unreliable and high time pressure, unreliable and low time pressure, and manual conditions. Participants were able to resolve the designated conflicts more accurately and faster in the reliable versus unreliable CRA conditions. When comparing the unreliable CRA and manual conditions, unreliable CRA led to better conflict resolution performance and higher situation awareness. Surprisingly, high time pressure triggered better conflict resolution performance as compared to the low time pressure condition. The findings from the present study highlight the importance of CRA in future ATC operations. Practitioner Summary: Conflict resolution aid (CRA) is a proposed automation decision aid in air traffic control (ATC). It was found in the present study that CRA was able to promote air traffic controllers' performance even when it was not perfectly reliable. These findings highlight the importance of CRA in future ATC operations.
International Nuclear Information System (INIS)
1975-01-01
The study consisted of a comparative evaluation of 2 nuclear units (Indian Point 2 - Consolidated Edison of New York, Turkey Point 4 - Florida Power and Light Company) and 2 coal-fired units (Bull Run and Widows Creek Unit 8 - Tennessee Valley Authority). The purpose of the study was to identify and assess the underlying causes of unit reliability and the causes of the observed differences in reliability performance of the units. Recommended actions for improving the reliability of one of the study units was to be presented in a format useful to other utility companies for improving reliability of their generating units. The emphasis of the study was on the aspects of management, manning, operations, and maintenance which had a significant impact on unit reliability. Volume 1 includes a summary, a description of the major findings from the comparative evaluation, conclusions based on these findings, and recommendations for improving the reliability of the below average units
Directory of Open Access Journals (Sweden)
Naseh Esmaeili
2017-06-01
Full Text Available Background : A number of studies have shown a clear relationship between diet and component of metabolic syndrome. Based on the Theory of Reasoned Action (TRA, attitude and subjective norm are factors affecting behavioral intention and subsequently behavior. The aim of the present study is to design a valid questionnaire identifying factors affecting nutritional behavior among patients with metabolic syndrome. Materials and Methods: Via literature review, six focus group discussion and interview with nutrition specialists were performed to develop an instrument based on the theory of reasoned action. To determine validity of the instrument, content and face validity analyses with 15 expert panels conducted and also to determine reliability, Cronbach’s Alpha coefficient performed. Results: A draft of 100 items questionnaire was developed and after evaluation of validity and reliability, final questionnaire included 46 items: 17 items for attitude, 13 items for subjective norms and 16 items for behavioral intention. For the final questionnaire average of content validity index was 0/92 and Cronbach’s Alpha coefficient was 0/85. Conclusion: Based on the results of the current study the developed questionnaire is a valid and reliable instrument and it can be used to identify factors affecting nutritional behavior among people with metabolic syndrome based on the theory of reasoned action.
Neeson, Thomas M; Van Rijn, Itai; Mandelik, Yael
2013-07-01
Ecologists and paleontologists often rely on higher taxon surrogates instead of complete inventories of biological diversity. Despite their intrinsic appeal, the performance of these surrogates has been markedly inconsistent across empirical studies, to the extent that there is no consensus on appropriate taxonomic resolution (i.e., whether genus- or family-level categories are more appropriate) or their overall usefulness. A framework linking the reliability of higher taxon surrogates to biogeographic setting would allow for the interpretation of previously published work and provide some needed guidance regarding the actual application of these surrogates in biodiversity assessments, conservation planning, and the interpretation of the fossil record. We developed a mathematical model to show how taxonomic diversity, community structure, and sampling effort together affect three measures of higher taxon performance: the correlation between species and higher taxon richness, the relative shapes and asymptotes of species and higher taxon accumulation curves, and the efficiency of higher taxa in a complementarity-based reserve-selection algorithm. In our model, higher taxon surrogates performed well in communities in which a few common species were most abundant, and less well in communities with many equally abundant species. Furthermore, higher taxon surrogates performed well when there was a small mean and variance in the number of species per higher taxa. We also show that empirically measured species-higher-taxon correlations can be partly spurious (i.e., a mathematical artifact), except when the species accumulation curve has reached an asymptote. This particular result is of considerable practical interest given the widespread use of rapid survey methods in biodiversity assessment and the application of higher taxon methods to taxa in which species accumulation curves rarely reach an asymptote, e.g., insects.
Riese, H.; Vrijkotte, T.; Meijer, P.; Kluft, C.; Geus, E. de
1999-01-01
Interactions between lipoproteins and fibrinolytic parameters inducing cardiovascular disease are gradually being disclosed. The multivariate analyses often used in studies investigating this relationship implicitly assume 1) that the reliability of the parameters in a cluster is comparably high,
Human Factors Reliability Analysis for Assuring Nuclear Safety Using Fuzzy Fault Tree
International Nuclear Information System (INIS)
Eisawy, E.A.-F. I.; Sallam, H.
2016-01-01
In order to ensure effective prevention of harmful events, the risk assessment process cannot ignore the role of humans in the dynamics of accidental events and thus the seriousness of the consequences that may derive from them. Human reliability analysis (HRA) involves the use of qualitative and quantitative methods to assess the human contribution to risk. HRA techniques have been developed in order to provide human error probability values associated with operators’ tasks to be included within the broader context of system risk assessment, and are aimed at reducing the probability of accidental events. Fault tree analysis (FTA) is a graphical model that displays the various combinations of equipment failures and human errors that can result in the main system failure of interest. FTA is a risk analysis technique to assess likelihood (in a probabilistic context) of an event. The objective data available to estimate the likelihood is often missing, and even if available, is subject to incompleteness and imprecision or vagueness. Without addressing incompleteness and imprecision in the available data, FTA and subsequent risk analysis give a false impression of precision and correctness that undermines the overall credibility of the process. To solve this problem, qualitative justification in the context of failure possibilities can be used as alternative for quantitative justification. In this paper, we introduce the approach of fuzzy reliability as solution for fault tree analysis drawbacks. A new fuzzy fault tree method is proposed for the analysis of human reliability based on fuzzy sets and fuzzy operations t-norms, co-norms, defuzzification, and fuzzy failure probability. (author)
Energy Technology Data Exchange (ETDEWEB)
Kutter, R
1981-12-04
Physical theories to inquire lifetime and reliability of mechanical structures or components under multiscale random stress do not exist. Today those dates were examinated e.g. in development of aircrafts and motorcars by fatigue-testing of original components and sections during long terms. Knowing the distributions of stress and material-parameters the same testing is to be realized simulationary on highspeed computers. This study gives methods to reduce the necessary computation time to attending ones even to proof reliability up to R=1-10/sup -9/. These methods were of Monte-Carlo-Simulation with weighted parameters and respect to life-history.
Factor Structure of the Exercise Self-Efficacy Scale
Cornick, Jessica E.
2015-01-01
The current study utilized exercise self-efficacy ratings from undergraduate students to assess the factor structure of the Self-Efficacy to Regulate Exercise Scale (Bandura, 1997, 2006). An exploratory factor analysis (n = 759) indicated a two-factor model solution and three separate confirmatory factor analyses (n = 1,798) supported this…
Factor structure underlying components of allostatic load.
Directory of Open Access Journals (Sweden)
Jeanne M McCaffery
Full Text Available Allostatic load is a commonly used metric of health risk based on the hypothesis that recurrent exposure to environmental demands (e.g., stress engenders a progressive dysregulation of multiple physiological systems. Prominent indicators of response to environmental challenges, such as stress-related hormones, sympatho-vagal balance, or inflammatory cytokines, comprise primary allostatic mediators. Secondary mediators reflect ensuing biological alterations that accumulate over time and confer risk for clinical disease but overlap substantially with a second metric of health risk, the metabolic syndrome. Whether allostatic load mediators covary and thus warrant treatment as a unitary construct remains to be established and, in particular, the relation of allostatic load parameters to the metabolic syndrome requires elucidation. Here, we employ confirmatory factor analysis to test: 1 whether a single common factor underlies variation in physiological systems associated with allostatic load; and 2 whether allostatic load parameters continue to load on a single common factor if a second factor representing the metabolic syndrome is also modeled. Participants were 645 adults from Allegheny County, PA (30-54 years old, 82% non-Hispanic white, 52% female who were free of confounding medications. Model fitting supported a single, second-order factor underlying variance in the allostatic load components available in this study (metabolic, inflammatory and vagal measures. Further, this common factor reflecting covariation among allostatic load components persisted when a latent factor representing metabolic syndrome facets was conjointly modeled. Overall, this study provides novel evidence that the modeled allostatic load components do share common variance as hypothesized. Moreover, the common variance suggests the existence of statistical coherence above and beyond that attributable to the metabolic syndrome.
DEFF Research Database (Denmark)
Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard
2016-01-01
structural reliability are assessed when the extreme turbulence model is uncertain. The structural reliability is assessed for the wind turbine when three configurations of an industrial grade load alleviation control system of increasing complexity and performance are used. The load alleviation features......The wind energy industry is continuously researching better computational models of wind inflow and turbulence to predict extreme loading (the nature of randomness) and their corresponding probability of occurrence. Sophisticated load alleviation control systems are increasingly being designed...... and deployed to specifically reduce the adverse effects of extreme load events resulting in lighter structures. The main objective herein is to show that despite large uncertainty in the extreme turbulence models, advanced load alleviation control systems yield both a reduction in magnitude and scatter...
International Nuclear Information System (INIS)
Embrey, D.E.
1983-05-01
The first part of the report considers the nature of human reliability assessment, and the techniques currently employed. It is concluded that most approaches are limited by the availability of data. Approaches to the subjective assessment of error are surveyed. A particular technique which has been developed, the Success Likelihood Index Methodology (SLIM), is described in detail, together with the practical steps for its implementation. The results from a trial application of a questionnaire designed to elicit judges' perceptions of the relative importance of performance shaping factors in determining human reliability are analyzed. A revised form of the questionnaire is presented for future use. A pilot experiment to investigate the relationship between subjectively derived indices of success for six tasks and their objective probability of success is described. The results indicate that the SLIM has potential value as a predictive technique. Some requirements for a program of research to produce a generally applicable methodology are set out
Sharif Nia, Hamid; Pahlevan Sharif, Saeed; Boyle, Christopher; Yaghoobzadeh, Ameneh; Tahmasbi, Bahram; Rassool, G Hussein; Taebei, Mozhgan; Soleimani, Mohammad Ali
2018-04-01
This study aimed to determine the factor structure of the spiritual well-being among a sample of the Iranian veterans. In this methodological research, 211 male veterans of Iran-Iraq warfare completed the Paloutzian and Ellison spiritual well-being scale. Maximum likelihood (ML) with oblique rotation was used to assess domain structure of the spiritual well-being. The construct validity of the scale was assessed using confirmatory factor analysis (CFA), convergent validity, and discriminant validity. Reliability was evaluated with Cronbach's alpha, Theta (θ), and McDonald Omega (Ω) coefficients, intra-class correlation coefficient (ICC), and construct reliability (CR). Results of ML and CFA suggested three factors which were labeled "relationship with God," "belief in fate and destiny," and "life optimism." The ICC, coefficients of the internal consistency, and CR were >.7 for the factors of the scale. Convergent validity and discriminant validity did not fulfill the requirements. The Persian version of spiritual well-being scale demonstrated suitable validity and reliability among the veterans of Iran-Iraq warfare.
International Nuclear Information System (INIS)
Forsthoffer, W.E.
1992-01-01
In this article, the author details the development of an actual auxiliary system in order to fully understand the function of each major component and how it contributes to the total operation and reliability of the system. Only after the function of an auxiliary system is thoroughly understood, can one proceed to discuss specifications, design audits, testing, operation and preventive maintenance. The application selected will be to develop a pressurized lubrication and steam turbine control oil system for the critical equipment unit. This example was selected since many readers will be familiar with this type and because it provides a good foundation towards understanding fluid sealing systems. In the exercise that follow, he will define the system requirements and determine the system parameters. This information will then be used for component sizing
Directory of Open Access Journals (Sweden)
Tamrazyan Ashot Georgievich
2012-10-01
Full Text Available Accurate and adequate description of external influences and of the bearing capacity of the structural material requires the employment of the probability theory methods. In this regard, the characteristic that describes the probability of failure-free operation is required. The characteristic of reliability means that the maximum stress caused by the action of the load will not exceed the bearing capacity. In this paper, the author presents a solution to the problem of calculation of structures, namely, the identification of reliability of pre-set design parameters, in particular, cross-sectional dimensions. If the load distribution pattern is available, employment of the regularities of distributed functions make it possible to find the pattern of distribution of maximum stresses over the structure. Similarly, we can proceed to the design of structures of pre-set rigidity, reliability and stability in the case of regular load distribution. We consider the element of design (a monolithic concrete slab, maximum stress S which depends linearly on load q. Within a pre-set period of time, the probability will not exceed the values according to the Poisson law. The analysis demonstrates that the variability of the bearing capacity produces a stronger effect on relative sizes of cross sections of a slab than the variability of loads. It is therefore particularly important to reduce the coefficient of variation of the load capacity. One of the methods contemplates the truncation of the bearing capacity distribution by pre-culling the construction material.
Factor structure of the Tomimatsu-Sato metrics
International Nuclear Information System (INIS)
Perjes, Z.
1989-02-01
Based on an earlier result stating that δ = 3 Tomimatsu-Sato (TS) metrics can be factored over the field of integers, an analogous representation for higher TS metrics was sought. It is shown that the factoring property of TS metrics follows from the structure of special Hankel determinants. A set of linear algebraic equations determining the factors was defined, and the factors of the first five TS metrics were tabulated, together with their primitive factors. (R.P.) 4 refs.; 2 tabs
Reliability assessment of a bi-material notch: Strain energy density factor approach
Czech Academy of Sciences Publication Activity Database
Klusák, Jan; Knésl, Zdeněk
2010-01-01
Roč. 53, č. 2 (2010), s. 89-93 ISSN 0167-8442 R&D Projects: GA ČR GAP108/10/2049; GA ČR GA101/08/0994 Institutional research plan: CEZ:AV0Z20410507 Keywords : crack initiation * bi-material notch * strain energy density factor Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.073, year: 2010
International Nuclear Information System (INIS)
Henrichs, K.; Mueller-Brunecker, G.; Paretzke, H.G.
1983-08-01
This is the first time that dose factors are published in the literature, together with an assessment of their reliability with regard to the quantification of the dose received by the population in the Federal Republic of Germany due to incorporation if iodine isotopes, taking into account the given age distribution among the population. The calculation of dose factors is based on the latest dosimetric and metabolic models issued by the ICRP (ICRP-30), and the impact of the various parameters and their variability on the accuracy of dose factor determination is assessed. The procedure followed to calculate the dose due to incorporation on the basis of metabolic models (ICRP 1978 and ICRP 1979) is explained. The main data (such as half life, mean frequency per decay, mean energy in keV) are given for I-123, I-125, I-129, I-131, I-132, I-133, I-134, and I-135 (ICRP-30) and listed in tables. (orig./HP) [de
Energy Technology Data Exchange (ETDEWEB)
Oxstrand, J. (Vattenfall Ringhals AB, Stockholm (Sweden))
2010-12-15
The main goal of this Nordic Nuclear Safety Research Council (NKS) project is to produce guidance for how to use human reliability analysis (HRA) to strengthen overall safety. The project consists of two substudies: The Nordic Point of View - A User Needs Analysis, and The American Point of View - Insights of How the US Nuclear Industry Works with HRA. The purpose of the Nordic Point of View study was a user needs analysis that aimed to survey current HRA practices in the Nordic nuclear industry, with the main focus being to connect HRA to system design. In this study, 26 Nordic (Swedish and Finnish) nuclear power plant specialists with research, practitioner, and regulatory expertise in HRA, PRA, HSI, and human performance were interviewed. This study was completed in 2009. This study concludes that HRA is an important tool when dealing with human factors in control room design or modernizations. The Nordic Point of View study showed areas where the use of HRA in the Nordic nuclear industry could be improved. To gain more knowledge about how these improvements could be made, and what improvements to focus on, the second study was conducted. The second study is focused on the American nuclear industry, which has many more years of experience with risk assessment and human reliability than the Nordic nuclear industry. Interviews were conducted to collect information to help the author understand the similarities and differences between the American and the Nordic nuclear industries, and to find data regarding the findings from the first study. The main focus of this report is to identify potential HRA improvements based on the data collected in the American Point of View survey. (Author)
International Nuclear Information System (INIS)
Oxstrand, J.
2010-12-01
The main goal of this Nordic Nuclear Safety Research Council (NKS) project is to produce guidance for how to use human reliability analysis (HRA) to strengthen overall safety. The project consists of two substudies: The Nordic Point of View - A User Needs Analysis, and The American Point of View - Insights of How the US Nuclear Industry Works with HRA. The purpose of the Nordic Point of View study was a user needs analysis that aimed to survey current HRA practices in the Nordic nuclear industry, with the main focus being to connect HRA to system design. In this study, 26 Nordic (Swedish and Finnish) nuclear power plant specialists with research, practitioner, and regulatory expertise in HRA, PRA, HSI, and human performance were interviewed. This study was completed in 2009. This study concludes that HRA is an important tool when dealing with human factors in control room design or modernizations. The Nordic Point of View study showed areas where the use of HRA in the Nordic nuclear industry could be improved. To gain more knowledge about how these improvements could be made, and what improvements to focus on, the second study was conducted. The second study is focused on the American nuclear industry, which has many more years of experience with risk assessment and human reliability than the Nordic nuclear industry. Interviews were conducted to collect information to help the author understand the similarities and differences between the American and the Nordic nuclear industries, and to find data regarding the findings from the first study. The main focus of this report is to identify potential HRA improvements based on the data collected in the American Point of View survey. (Author)
DEFF Research Database (Denmark)
Ramirez, José Rangel; Sørensen, John Dalsgaard
2011-01-01
This work illustrates the updating and incorporation of information in the assessment of fatigue reliability for offshore wind turbine. The new information, coming from external and condition monitoring can be used to direct updating of the stochastic variables through a non-parametric Bayesian u...
Factor structure of the Body Appreciation Scale among Malaysian women.
Swami, Viren; Chamorro-Premuzic, Tomas
2008-12-01
The present study examined the factor structure of a Malay version of the Body Appreciation Scale (BAS), a recently developed scale for the assessment of positive body image that has been shown to have a unidimensional structure in Western settings. Results of exploratory and confirmatory factor analyses based on data from community sample of 591 women in Kuala Lumpur, Malaysia, failed to support a unidimensional structure for the Malay BAS. Results of a confirmatory factor analysis suggested two stable factors, which were labelled 'General Body Appreciation' and 'Body Image Investment'. Multi-group analysis showed that the two-factor structure was invariant for both Malaysian Malay and Chinese women, and that there were no significant ethnic differences on either factor. Results also showed that General Body Appreciation was significant negatively correlated with participants' body mass index. These results are discussed in relation to possible cross-cultural differences in positive body image.
International Nuclear Information System (INIS)
Lee, Chi Woo; Kim, Sun Jin; Lee, Seung Woo; Jeong, Sang Yeong
1993-08-01
This book start what is reliability? such as origin of reliability problems, definition of reliability and reliability and use of reliability. It also deals with probability and calculation of reliability, reliability function and failure rate, probability distribution of reliability, assumption of MTBF, process of probability distribution, down time, maintainability and availability, break down maintenance and preventive maintenance design of reliability, design of reliability for prediction and statistics, reliability test, reliability data and design and management of reliability.
DEFF Research Database (Denmark)
Mohanty, Sankhya; Hattel, Jesper Henri
2016-01-01
Repeatability and reproducibility of parts produced by selective laser melting is a standing issue, and coupled with a lack of standardized quality control presents a major hindrance towards maturing of selective laser melting as an industrial scale process. Consequently, numerical process...... modelling has been adopted towards improving the predictability of the outputs from the selective laser melting process. Establishing the reliability of the process, however, is still a challenge, especially in components having overhanging structures.In this paper, a systematic approach towards...... establishing reliability of overhanging structure production by selective laser melting has been adopted. A calibrated, fast, multiscale thermal model is used to simulate the single track formation on a thick powder bed. Single tracks are manufactured on a thick powder bed using same processing parameters...
Factor structure of the Childhood Autism Rating Scale as per DSM-5.
Park, Eun-Young; Kim, Joungmin
2016-02-01
The DSM-5 recently proposed new diagnostic criteria for autism spectrum disorder (ASD). Although many new or updated tools have been developed since the DSM-IV was published in 1994, the Childhood Autism Rating Scale (CARS) has been used consistently in ASD diagnosis and research due to its technical adequacy, cost-effectiveness, and practicality. Additionally, items in the CARS did not alter following the release of the revised DSM-IV because the CARS factor structure was found to be consistent with the revised criteria after factor analysis. For that reason, in this study confirmatory factor analysis was used to identify the factor structure of the CARS. Participants (n = 150) consisted of children with an ASD diagnosis or who met the criteria for broader autism or emotional/behavior disorder with comorbid disorders such as attention-deficit hyperactivity disorder, bipolar disorder, intellectual or developmental disabilities. Previous studies used one-, two-, and four-factor models, all of which we examined to confirm the best-fit model on confirmatory factor analysis. Appropriate comparative fit indices and root mean square errors were obtained for all four models. The two-factor model, based on DSM-5 criteria, was the most valid and reliable. The inter-item consistency of the CARS was 0.926 and demonstrated adequate reliability, thereby supporting the validity and reliability of the two-factor model of CARS. Although CARS was developed prior to the introduction of DSM-5, its psychometric properties, conceptual relevance, and flexible administration procedures support its continued role as a screening device in the diagnostic decision-making process. © 2015 Japan Pediatric Society.
International Nuclear Information System (INIS)
Petersen, K.E.
1986-03-01
Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very complex systems. In order to increase the applicability of the programs variance reduction techniques can be applied to speed up the calculation process. Variance reduction techniques have been studied and procedures for implementation of importance sampling are suggested. (author)