A New Model For Reliability Centered Maintenance In Petroleum Refineries

Refiners today operate their equipment for prolonged periods without shutdown. This is primarily due to the increased pressures of the market resulting in extended shutdown-to-shutdown intervals. This places extreme demands on the reliability of the plant equipment. The traditional methods of reliability assurance, like Preventive Maintenance, Predictive Maintenance and Condition Based Maintenance become inadequate in the face of such demands. The alternate approaches to reliability improvement, being adopted the world over are implementation of RCFA programs and Reliability Centered Maintenance. However refiners and process plants find it difficult to adopt this standardized methodology of RCM mainly due to the complexity and the large amount of analysis that needs to be done, resulting in a long drawn out implementation, requiring the services of a number of skilled people. These results in either an implementation restricted to only few equipment or alternately, one that is non-standard. The paper presents the current models in use, the core requirements of a standard RCM model, the alternatives to classical RCM, limitations in the existing model, classical RCM and available alternatives to RCM and will then go on to present an ‗Accelerated‘ approach to RCM implementation, that, while ensuring close conformance to the standard, does not place a large burden on the implementers

Reliability Estimation of Open Source Software based Computational Systems

Software systems are progressively being deployed in many facets of human life. The implication of the failure of such systems, has an assorted impact on its customers. The fundamental aspect that supports a software system, is focus on quality. Reliability describes the ability of the system to function under specified environment for a specified period of time and is used to objectively measure the quality. Evaluation of reliability of a computing system involves computation of hardware and software reliability. Most of the earlier works were given focus on software reliability with no consideration for hardware parts or vice versa. However, a complete estimation of reliability of a computing system requires these two elements to be considered together, and thus demands a combined approach. The present work focuses on this and presents a model for evaluating the reliability of a computing system. The method involves identifying the failure data for hardware components, software components and building a model based on it, to predict the reliability. To develop such a model, focus is given to the systems based on Open Source Software, since there is an increasing trend towards its use and only a few studies were reported on the modeling and measurement of the reliability of such products. The present work includes a thorough study on the role of Free and Open Source Software, evaluation of reliability growth models, and is trying to present an integrated model for the prediction of reliability of a computational system. The developed model has been compared with existing models and its usefulness of is being discussed.

The Influence of Adjacent Segment on the Reliability of Cu Dual Damascene Interconnects

Three terminal ‘dotted-I’ interconnect structures, with vias at both ends and an additional via in the middle, were tested under various test conditions. Mortalities (failures) were found in right segments with jL value as low as 1250 A/cm, and the mortality of a dotted-I segment is dependent on the direction and magnitude of the current in the adjacent segment. Some mortalities were also found in the right segments under a test condition where no failure was expected. Cu extrusion along the delaminated Cu/Si₃N₄ interface near the central via region was believed to cause the unexpected failures. From the time-to-failure (TTF), it is possible to quantify the Cu/Si₃N₄ interfacial strength and bonding energy. Hence, the demonstrated test methodology can be used to investigate the integrity of the Cu dual damascene processes. As conventionally determined critical jL values in two-terminal via-terminated lines cannot be directly applied to interconnects with branched segments, this also serves as a good methodology to identify the critical effective jL values for immortality.

Effects of the heterogeneity of the variances on reliability generalization : An example with the beck depression inventory

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Validity and reliability pie

Validity and reliability pie animation for display in RM&EBP

Assessment of construct validity and reliability of the inventory of masculinity and femininity in adolescents and young adults Colombian

This study evaluated the construct validity and reliability of Femininity and Masculinity Inventory-Imafe (Lara, 1993), and calculated standardized punctuations for Colombian teenagers and young adults. Participants were 1527 male and female, between 15 and 42. The general and scale reliability was evaluated through Alfa and Guttmann coefficients, and the factor analysis was used to estimate the construct validity. Standardized punctuations were obtained for gender, since there were statistically significant differences for sex in the six scales of the instrument. The inventory presented reliability values that oscillated between .76 and .88, and the factorial analysis showed three factors coherent with the factors found in its original validation. Correlacional inter-scales analysis and sex-differences were theoretically consistent.

Interrater reliability of Alberta Infant Motor Scale in term and preterm born infants between 10 to 16 months age from Talca province - Chile

Purpose: To examine the ‘interrater reliability’ of the Alberta Infant Motor Scale (AIMS) in term and preterm born infants between 10 to 16 months age from Talca province, Maule Region - Chile. Subjects: 115 infants between 10 to 16 months age were incorporated to the study; 95 term born infants were attended in the local Health Centre in Talca City, and 20 preterm infants belonged to the Premature Infants Follow-Up Programme of Talca Regional Hospital. Methods: The motor behaviour of each infant was recorded and later it was assessed by two trained assessors using AIMS. It was obtained the total AIMS’ score and also from prone, supine, seated, and stand subscales. For ‘interrater reliability’ analysis it was used the Intraclass Coefficient of Correlation (ICC), the Standard Error of Measurement (SEM) and 95% limits of agreement. Results: The obtained ICC for the total scores AIMS were major than 0.94 (p<0.0002) for term and preterm born infants. The SEM of total scores was less than 3.1 points, higher than what was found in other similar studies. The 95% limits of agreement were +5.3 to -4.1 points and +7.7 to – 3.9 points in term and preterm born, respectively, revealing ‘interrater agreement’. Conclusion: The AIMS showed adequate ‘interrater reliable’ levels when was applied in Chilean term and preterm born from 10 to 16 month’s age.

Can consumer complaints reduce product reliability? Should we worry?

We analyze a monopolist’s pricing and product reliability problem when consumers are entitled to product replacement but have heterogeneous cost of exercising this right, and we assess the implications of a decrease in consumers’ claiming cost on reliability, profit, and welfare. We find that reducing consumers’ claiming cost may reduce reliability and increase profit. Additionally, the model can explain why some firms encourage consumers to complain while others discourage consumers from complaining. We also show that welfare and profit are partially aligned, specially when consumers’ claiming cost are relatively low and the firm prefers to promote complaints; consequently, we find that encouraging complaints will eventually increase welfare

Traducción, adaptación y validación del cuestionario OCFQ para medir las fallas cognitivas ocupacionales en el contexto cultural Colombiano, 2015.

Objetivos. El Objetivo general de este estudio es determinar si el Instrumento para evaluar las Fallas Cognitivas Ocupacionales (Occupational Cognitive Failures Questionnaire - OCFQ) desarrollado por Allahyari T. et al. (2011) , tiene validez transcultural y podría ser un Instrumento fiable y válido que se puede adaptar al contexto cultural Colombiano para la valoración de las Fallas Cognitivas en el ámbito laboral. Metodología. Se llevó a cabo la traducción, adaptación y validación del Cuestionario de Fallas Cognitivas Ocupacionales (OCFQ) al contexto cultural colombiano, siguiendo las recomendaciones de la Organización Mundial de la Salud (OMS) para el proceso de traducción y adaptación de instrumentos y posteriormente la evaluación de fiabilidad y validez del instrumento adaptado, en cuatro etapas: Etapa 1. Traducción - retro traducción, Etapa 2. “Debriefing” y Análisis de legibilidad, Etapa 3. Validez de contenido, usando el Índice de Validez de Contenido (CVI) y Etapa 4. Evaluación de propiedades métricas. Para la evaluación de Validez de Constructo se aplicó el Análisis Factorial por el Método de Componentes Principales y Rotación Varimax; la consistencia interna y la estabilidad temporal fueron evaluados mediante el Alpha de Cronbach (α) y el test-retest, respectivamente. Resultados. El Cuestionario OCFQ fue adaptado al contexto cultural Colombiano; el análisis de Legibilidad determinó que de acuerdo con el Grado en la escala Inflesz, el Cuestionario es Bastante Fácil de leer. Partiendo de la versión original de 30 ítems se obtuvo una nueva versión de 25 ítems, ya que después de la evaluación de Validez de Contenido se rechazaron 5 ítems. El Índice de Validez de Contenido (CVI) para la versión final del OCFQ adaptado es aceptable (CVI=0,84). Los resultados de las pruebas métricas muestran que la versión final del OCFQ adaptado tiene una buena Consistencia Interna (α=0.90) y el Índice de Correlación Interclases (ICC) fue de 0.91 mostrando una muy buena Estabilidad Temporal. El Análisis Factorial estableció para el Cuestionario OCFQ 4 factores que explican el 47% de la varianza total. Conclusión. La evaluación de las Fallas Cognitivas en el ámbito laboral requiere que se disponga de una herramienta válida y fiable. De acuerdo con los resultados en este estudio se puede establecer que el OCFQ adaptado al Contexto Cultural Colombiano podría ser un instrumento adecuado para medir las Fallas Cognitivas en el ámbito laboral en plantas industriales.

Estimating the reliability coefficient of tests in presence of missing values

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Validity and reliability of the Spanish version of the Displaced Aggression Questionnaire

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SN10: reliability and validity

This study discusses a study to assess reliability and validity of the 500 Hz SN10 for adult, non-sedated patients.

The reliability and validity of monitored connected discourse as a test of the threshold of intelligibility

This paper discusses a study undertaken to determine whether a normal hearing person or hearing impaired person can reliably select a threshold of intelligibility and if so, whether this can be considered a valid measurement.