Search results for "reliability"
showing 10 items of 1563 documents
Handling stakeholder uncertain judgments in strategic transport service analyses
2013
Abstract The quality level of services has to be constantly controlled, especially under conditions of competition increasing and limited resources. However, considering that service performance analyses are based on stakeholders' judgments, they can be characterized by possible uncertainties related to incompleteness for partial ignorance, imprecision for subjectivity and even vagueness. Therefore, under these conditions, unreliable results can be obtained by widely used service analysis methodologies. In the present paper, a methodology based on a recent extension of the SERVQUAL model, and that uses in combined manner the fuzzy set theory and the analytic hierarchy process method is prop…
Stochastic Fatigue Models for Efficient Planning Inspections in Service of Aircraft Structures
2008
For important fatigue-sensitive structures of aircraft whose breakdowns cause serious accidents, it is required to keep their reliability extremely high. In this paper, we discuss inspection strategies for such important structures against fatigue failure. The focus is on the case when there are fatiguecracks unexpectedly detected in a fleet of aircraft within a warranty period (prior to the first inspection). The paper examines this case and proposes stochastic models for prediction of fatigue-crack growth to determine appropriate inspections intervals. We also do not assume known parameters of the underlying distributions, and the estimation of that is incorporated into the analysis and d…
An Observation Framework for Multi-agent Systems
2009
Existing middleware platforms for multi-agent systems (MAS) do not provide general support for observation. On the other hand, observation is considered to be an important mechanism needed for realizing effective and efficient coordination of agents. This paper describes a framework called Agent Observable Environment (AOE) for observation-based interaction in MAS. The framework provides 1) possibility to model MAS components with RDF-based observable soft-bodies, 2) support for both query and publish/subscribe style ontology-driven observation, and 3) ability to restrict the visibility of observable information using observation rules. Additionally, we report on an implementation of the fr…
Evaluating Infrastructure Alternatives for Regional Water Supply Systems by Model-assisted Cost-benefit Analysis – A Case Study from Apulia, Italy
2014
The main challenge associated to regional water supply systems planning lies in understanding the best infrastructure alternatives to improve service given a certain configuration of the resources system. While cost-effectiveness assessments are still widespread in this type of analyses, they do not account for the fact that, especially in mature systems, service improvements tend to follow the law of marginal diminishing returns, so that a cost – benefit assessment should be preferable. Both costs and benefits can be organized into a cost-benefit analysis (CBA) framework. In a complex system, a model reproducing its topology and characteristics better describes the impacts of the alternati…
Inspection Policies in Service of Fatigued Aircraft Structures
2011
Fatigue is one of the most important problems of aircraft arising from their nature as multiple-component structures, subjected to random dynamic loads. For guaranteeing safety, the structural life ceiling limits of the fleet aircraft are defined from three distinct approaches: Safe-Life, Fail-Safe, and Damage Tolerance approaches. The common objectives to define fleet aircraft lives by the three approaches are to ensure safety while at the same time reducing total ownership costs. In this paper, the damage tolerance approach is considered and the focus is on the inspection scheme with decreasing intervals between inspections. The paper proposes an analysis methodology to determine appropri…
A Simulation Analysis for Assessing the Reliability of AC/DC Hybrid Microgrids - Part I: Underground Station and Car Parking
2021
This paper reports the results of a simulation study with the aim of evaluating the capability of two portions of a hybrid AC/DC MV/LV network of maintaining their operation in off-grid mode during the loss of the main AC grid due to a failure. In particular, the study aims to verify, in the case of islanded operation of the two microgrids, the continuity of the electricity service by exploiting the local generation plants, Energy Storage Systems (ESSs), and other flexible resources managed by suitable algorithms in different energy scenarios. The analysis was carried out considering two microgrids: an underground station and a car parking with Electric Vehicles (EVs). For assessing the per…
Antecedents of online banking satisfaction and loyalty: empirical evidence from Finland
2009
This study endeavours to contribute to a better understanding of Service Quality (SQ) in online banking by examining the various dimensions related to creating a satisfactory online banking experience. The authors develop a conceptual model and test it with a convenience sample of 183 online banking users. The empirical test of the model finds strong support for the links between perceived security and Perceived Usefulness (PU) and Perceived Ease Of Use (PEOU), reliability and PU and PEOU, between PEOU and satisfaction and finally between satisfaction and loyalty. The study finally provides both theoretical and practical contributions, outlines the main limitations of the study and gives id…
The Assessment of Perceived Service Quality of Public Health Care Services in Romania Using the SERVQUAL Scale
2013
Abstract The objective of this paper is to explore the application of the original SERVQUAL scale in the context of public health care services in Romania. More specifically, we implemented the SERVQUAL scale in order to uncover whether it fits as the original version or adjustments should be done and to define the demographic profiles of health care consumers who use public services in Romania. We have selected our sample respondents from a list of a gynaecological health care forum members, namely women from Bucharest who should have posted messages on the chosen forum no more than three months before the study was conducted and the messages should have comprised their experiences with ce…
On the packing sums of pairs
1993
Abstract This paper is concerned with the determination of the length of the largest interval of consecutive integers of the set hA k , where A k is a sequence of integers which is a B h -sequence.
ADC based measurements: Identification of the parameters for the uncertainty evaluation
2009
In the last years, many Authors have dealt with the uncertainty evaluation of the measurement performed by using an analog-to-digital converter, proposing different approach to analyze the uncertainty propagation. In all these studies, it is clearly pointed out that starting from the manufacturer specifications is the least expensive, the least time consuming and, often, the most accurate way to assess the uncertainties. However, the Authors, which have proposed methodologies for the uncertainty assessment, use different parameters as starting point. One of the main reasons which has caused this situation is the coexistent of various Standards concerning the characterization of the analog-t…