Search results for "Reliability engineering"
showing 10 items of 224 documents
Technical and economical evaluation on the use of reconfiguration systems in some EU countries for PV plants
2017
This paper shows the technical and economical evaluation of the application of a reconfiguration system for photovoltaic (PV) plants, considering the incentives system in some European Union countries. The reconfiguration system is an alternative to the distributed maximum power point tracking technique which used to increase the power production in the PV plants under the mismatch phenomenon. The reconfiguration techniques employ a microprocessor-based or field-programmable gate array-based system that modifies the layout of the PV plant through the change of the connections among modules. After having presented the main features working of the PV reconfiguration system allowing the improv…
A comprehensive tool for efficient design and operation of polygeneration-based energy μgrids serving a cluster of buildings. Part II: Analysis of th…
2013
Abstract The potential of polygeneration systems, in terms of profitability, energy saving and pollutant emissions reduction, highly depends on several factors such as plant efficiency, local normative and tariff conditions and reference technologies adopted to compare the results. In Part I of this paper a reliable tool was described, capable of optimizing the lay-out, design and operation of an integrated polygeneration system serving a cluster of buildings with their heat, cooling and power demand; the tool represents an excellent instrument to perform sensitivity analyses, thus enabling the analyst to formulate general design criteria and predict the effects of any change in the boundar…
A force measuring based strategy for failure prevention in incremental forming
2006
Abstract Incremental forming processes show a number of advantages compared to the traditional processes but, at the same time, some drawbacks are clearly known. Current problems, include the slowness of the process, low accuracy and a lack of knowledge in the field of material formability. This paper is focused on the latter issue: an industrially oriented methodology for detecting the approach of failure in incremental forming is proposed. The approach is based on the analysis of the trend of the forming force in order to assess whether the process can be run safely. If not, a proper strategy, to avoid material failure, is proposed and experimentally validated.
Fault diagnosis and modeling of the liquids packaging process. A research based on Petri Nets
2008
Searching for solutions to manufacture industries, which every day deal with problems of faults in their process, that generate economics and humans main losses, an algorithm to construct a Petri Nets based model and diagnoser to isolate and fault detection of discrete events systems is presented. This algorithm is developed in a real process of liquids packaging, where we can see that its implementation allows detecting individuals, simultaneous and dependents faults. The process to construct the model and diagnoser is systematic and useful, and it reduces the problems of combinational explosion, which is the main problem present in other investigations. This research has an excellent proj…
Validation of the group nuclear safety climate questionnaire.
2013
Abstract Introduction Group safety climate is a leading indicator of safety performance in high reliability organizations. Zohar and Luria (2005) developed a Group Safety Climate scale (ZGSC) and found it to have a single factor. Method The ZGSC scale was used as a basis in this study with the researchers rewording almost half of the items on this scale, changing the referents from the leader to the group, and trying to validate a two-factor scale. The sample was composed of 566 employees in 50 groups from a Spanish nuclear power plant. Item analysis, reliability, correlations, aggregation indexes and CFA were performed. Results Results revealed that the construct was shared by each unit, a…
A combined multi-criteria approach to support FMECA analyses: A real-world case
2018
[EN] The paper proposes an approach that combines reliability analyses and multi-criteria decision methods to optimize maintenance activities of complex systems. A failure mode, effects, and criticality analysts (FMECA) is initially performed and the fuzzy TOPSIS (FTOPSIS) method is then applied to rank previously identified failure modes. For prioritization, failure modes are assessed against three evaluation criteria that differ from those traditionally involved in risk priority number (RPN) computation (i.e. severity, occurrence and detection). Two criteria refer to the maintenance management reflecting the operational time taken by the maintenance activity performed after the occurrence…
An optimized diagnostic architecture for real-time monitoring of MV networks
2006
Due to the electrical energy market liberalization, the Authority for electrical energy and gas (AEEG) in Italy and the other regulatory organizations in other European countries have concentrated their attention on the quality of the electrical service. One of the aspect of major importance in the definition of the quality of a public service is its continuity. In the aim of regulating this field the Authority has defined some continuity indicators, for example the number of interruptions per year and the cumulate duration of the interruptions per year. Recent statistics on these indicator show that the 80% of the number of interruptions in one year is caused by MV network. For this reason…
A procedure to calculate the five-parameter model of crystalline silicon photovoltaic modules on the basis of the tabular performance data
2013
Abstract Only few manufactures provide the wide set of graphical data that are necessary to use high performance predictive tools for PV systems. On the other hand, reliable graphical data require accurate laboratory measurements that increase manufacturing costs. For this reason PV system designers have to choose between the use of cheap PV modules, lacking in technical data, and the reliable energy predictions that are possible only if the current–voltage characteristics are provided by the PV module manufacturers. This paper describes the procedure to evaluate the parameters of a one-diode equivalent circuit able to accurately represent the electrical behaviour of a PV panel by means of …
Sensitivity analysis to quantify uncertainty in Life Cycle Assessment: The case study of an Italian tile
2011
Abstract The results of a Life Cycle Assessment (LCA) study can be affected by several uncertainty sources, mainly due to the methodological choices, the initial assumptions, i.e. allocation rules, system boundaries and impact assessment methods, and the quality of the available data. Then, the experts should estimate the extent of the above-mentioned sources of uncertainty for improving the reliability and the representativeness of the obtained eco-profiles. To estimate the uncertainty is necessary to obtain reliable, transparent and representative LCA results and to correctly support decision-makers in the selection of different product or process options. The following paper starts from …
Review of the energy and economic parameters involved in the effectiveness of grid-connected PV systems installed in multi-storey buildings
2014
Abstract The assessment of PV energy in an urban context is extremely complex because many factors have to be considered. Moreover, when the purpose is calculating the realistic amount of the electricity demand of a city that can be covered by the photovoltaic generation, it is necessary to estimate the number of photovoltaic systems whose installation is economically advantageous. Such a topic requires an economic analysis, which is affected by the number of energy and economic parameters involved and the values assigned to them to perform calculations. Some parameters are perfectly known and unvarying, like the paid incentives. Adversely, some parameters, like the efficiency degradation o…