Search results for "Reliability"
showing 10 items of 1563 documents
Emergent vulnerabilities in Integrated Operations: A proactive simulation study of economic risk
2009
Abstract The protection of critical infrastructure requires an understanding of the effects of change on current and future safety and operations. Vulnerabilities may emerge during the rollout of updated techniques and integration of new technology with existing work practices. Managers need to understand how their decisions, often focused on economic priorities, affect the dynamics of vulnerability over time. Such understanding is difficult to obtain, as the historical data typically used for decision support, prediction and forecasting may not be available. We report on the use of group model building and simulation to consider proactively the effects of a 10-year, multi-billion dollar mo…
A Fuzzy Inference Expert System to Support the Decision of Deploying a Military Naval Unit to a Mission
2009
Naval military units are complex systems required to operate in fixed time frames in offshore tasks where maintenance operations are drastically limited. A failure during a mission is a critical event that can drastically influence the mission success. The decision of switching a unit to a mission hence requires complex judgments involving information about the health status of machineries and the environmental conditions. The present procedure aims to support the decision about switching a unit to a mission considering the vagueness and uncertainty of information by means of fuzzy theory and emulates the decision process of a human expert by means of a rule-based inference engine. A numeri…
Using partial-orders for detecting faults in concurrent systems
1998
The paper suggests test derivation approaches to obtain test suites for concurrent systems based on the concept of fault coverage criteria in opposition to structural test coverage criteria. Using a partial-order model, called Mazurkiewicz Trace Machine (MTM), for test derivation, the state explosion problem can be alleviated. The derived test suites are characterized by their small size compared to test suites from traditional test derivation approaches and exhibit a defined degree of fault coverage according to certain fault models. The fault models of concurrent systems considered in the paper are based on the most common faults, acceptance, refusal, and transfer faults. A scenario of te…
Effects of Demand Side Management on the Operation of an Isolated LV Microgrids
2019
The work presents the results of a study regarding the impact of Demand Side Management actions on flexible loads distributed at the domestic end-users' facilities in an isolated low voltage microgrid. Aim of the research study is to evaluate how the implementation of local control actions on the end-user's side can impact on the operation of the isolated microgrid. The Demand Side Management is applied by each domestic user to optimize the operation of its own resources following well-defined operative steps. The study is carried out implementing a suitable model of the microgrid in Neplan environment, while the daily controlled load profiles of the end-users are evaluated using the Montec…
Assessing therapist development: Reliability and validity of the Supervisee Levels Questionnaire (SLQ-R).
2019
BACKGROUND Therapist development is a crucial target for clinical training in order to ensure high-quality psychotherapy. A major challenge in examining therapeutic development is the assessment of developmental processes. The Supervisee Levels Questionnaire (SLQ-R) was analyzed in this study to examine its validity, reliability, and underlying dimensional structure. METHOD Seven hundred and sixty therapists participated in an online survey concerning their current psychotherapy training. The factor structure as well as the validity of the SLQ-R were investigated using exploratory and confirmatory factor analysis. RESULTS In line with the results of the exploratory factor analyses, a Bifact…
Propiedades psicométricas y estructura de los factores de la escala de Satisfacción con la Vida en una muestra de estudiantes mayores portugueses jub…
2018
Abstract The main purpose of this study is to analyse the psychometric properties of the Satisfaction with Life Scale (SWLS) in a 363 retirees students sample from several Portuguese universities. The 70% were female (253) and 30% were male (110) with an average age of 67 years (SD = 7.59) and a range from 48 to 90 years. R Commander was used for Exploratory Factor Analysis (EFA) and Amos 18.0 module for Confirmatory Factor Analysis (CFA). One factor solution was the best-fitting model. The internal consistency of the SWLS was .777. Correlational analysis showed negative relationships with loneliness (UCLA Scale) and symptoms of depression (GDS-15), supporting concurrent validity. The SWLS …
Random Slicing: Efficient and Scalable Data Placement for Large-Scale Storage Systems
2014
The ever-growing amount of data requires highly scalable storage solutions. The most flexible approach is to use storage pools that can be expanded and scaled down by adding or removing storage devices. To make this approach usable, it is necessary to provide a solution to locate data items in such a dynamic environment. This article presents and evaluates the Random Slicing strategy, which incorporates lessons learned from table-based, rule-based, and pseudo-randomized hashing strategies and is able to provide a simple and efficient strategy that scales up to handle exascale data. Random Slicing keeps a small table with information about previous storage system insert and remove operations…
The comparison of reliabilities in dental imaging methods.
2003
Objectives: Common practice in the statistical comparison of imaging instruments with limited reproducibility consists in the separate estimation of the instrument's reliabilities. However, as soon as one of the imaging methods is subject to item-specific bias (which has to be expected in many dentomaxillofacial imaging procedures), this approach will end in severe errors in reliability computation and in corresponding erroneous clinical conclusions. This paper seeks to point out these effects and to illustrate a more appropriate model for the comparison of instrumental reliabilities. Methods: A standard reliability model was adjusted for item-specific bias and illustrated by the comparison…
On the Reliability of Error Indication Methods for Problems with Uncertain Data
2012
This paper is concerned with studying the effects of uncertain data in the context of error indicators, which are often used in mesh adaptive numerical methods. We consider the diffusion equation and assume that the coefficients of the diffusion matrix are known not exactly, but within some margins (intervals). Our goal is to study the relationship between the magnitude of uncertainty and reliability of different error indication methods. Our results show that even small values of uncertainty may seriously affect the performance of all error indicators.
On a linear diophantine problem of Frobenius
1993
Abstract In this paper, linear diophantine problem of Frobenius is discussed. A theorem concerning the largest integer g m (a1,a2) and the smallest integer G m (a1,a2) with m different representations with a1,a2 as basis is proved.