Search results for "Maintenance engineering"
showing 10 items of 20 documents
Diagnosis of intermittent fault dynamics
2008
Diagnosis of intermittent faults is relevant for productive processes with a high level of maintenance caused by such failures. A characterization of diagnosed faults may save unnecessary repairs and enable better maintenance planning. This paper introduces the concept of diagnosis of intermittent fault dynamics. Moreover, a methodology for modelling intermittent faults and generating information for maintenance planning in discrete event systems is thoroughly covered.
GIS systems and LIDAR technology for the operation of HV lines. Sicilian transmission network applications
2013
The difficulties to build new power lines within the national territory cause of authorization problems, and the evermore growing production of electricity from renewable sources, induces Terna S.p.A. (Italian TSO) to take advantage of existing overhead transmission lines. Therefore, in order to increase the transmission capacity, and to optimize the maintenance and management of power lines, for some years Terna has been using a software in GIS environment (Geographic Information System) that referring to the LIDAR (Laser Imaging Detection and Ranging) remote sensing technology, allows to manage the interferences according to all the requirements and legislative bonds and to fulfill the im…
Using semantics to facilitate data integration of offshore wind farms
2012
Operation and maintenance play an important role in extracting power from the wind, especially, in offshore wind energy where wind farms are located far off the shore and under harsh weather conditions. Improved operation and maintenance is likely to reduce costs as well as hazard exposure of the employees. Implementation of advanced information technology is thus crucial for operating offshore wind farms effectively and efficiently and hence improves operation and maintenance. However, information availability and reliability are key issues for their use in the offshore wind domain. In addition, the semantic of information has not been exploited thoroughly. This paper describes the develop…
Vibration signature analysis for rotor broken bar diagnosis in double cage induction motor drives
2013
The paper investigates the diagnosis of rotor broken bars in field oriented controlled (FOC) double cage induction motor drives, using current and vibration signature analysis techniques. The Impact of the closed loop control system cannot be neglected when the detection of asymmetries in the machine are based on the signature analysis of electrical variables. The proposed diagnosis approach is based on optimized use of wavelet analysis by a pre-processing of phase current or axial/radial vibration signals. Thus, the time evolution of the tracked rotor fault components can be effectively analyzed. This paper shows also the relevance of the fault components computed from axial vibration sign…
Extended friction model of a hydraulic actuated system
2012
The main contribution of this paper is an experimental validation and comparison of three different friction models for an electro-hydraulic servo system. The first is the well-kn own LuGre model which incorporates dynamic friction effects. The second model is based on a relatively recent publication by Yanada in 2008 [6], which incorporates liquid film thickness in the servo valve. The third model is a new contribution presented in this paper, where valve underlap and mass acceleration are combined with the LuGre model. The experimental results show that for hydraulic systems, the film thickness model is an improvement over the LuGre model, while the new model presented in this paper is an…
Dynamics photovoltaic generators: Technical aspects and economical valuation
2010
The strategy adopted from many European nations and not, to entrust the electric energy production to differently energetic sources has determined an increment of the scientific research for the solar resource exploitation. These scientific community activities follows with attention from the entrepreneurial world have concentrated on the innovative techniques and methodologies of the source conversion, solar concentration and the direction's device optimization. This job focuses its attention on the simple application of solar-track device, based on consolidated technologies. The diffused application of these dispositive, could be, shortly, an important increment of electricity generation …
A comprehensive study of automatic program repair on the QuixBugs benchmark
2021
Abstract Automatic program repair papers tend to repeatedly use the same benchmarks. This poses a threat to the external validity of the findings of the program repair research community. In this paper, we perform an empirical study of automatic repair on a benchmark of bugs called QuixBugs, which has been little studied. In this paper, (1) We report on the characteristics of QuixBugs; (2) We study the effectiveness of 10 program repair tools on it; (3) We apply three patch correctness assessment techniques to comprehensively study the presence of overfitting patches in QuixBugs. Our key results are: (1) 16/40 buggy programs in QuixBugs can be repaired with at least a test suite adequate pa…
Combined fuzzy TOPSIS and AHP-based methodology for the prioritization of maintenance key performance indicators: Application to an oil refinery plant
2017
A Maintenance Performance Measurement model based on the use of Maintenance Key Performance Indicators (MKPIs) is proposed in the present paper. Referring to a specific industrial context, a multi-level hierarchical structure is firstly designed to highlight the most meaningful perspectives which affect the maintenance performance. Then, MKPIs selected from the literature or properly formulated to detail some particular perspective of the investigated maintenance process are assigned to the hierarchical framework and prioritized by a Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (FTOPSIS) and Analytic Hierarchy Process (AHP)-based approach.
A Survey of Current Measurement Methods for eGovernment User-Satisfaction
2011
A survey on eGovernment user-satisfaction measurement methods was conducted to enable a comparison among them and to facilitate a discussion on good practices. The collected information is related to the methodology properties, tools, followed practices, implementation stage and challenges. The main findings are that the surveyed methods rarely refer to any established relevant standards, they are not regularly updated, and most of them do not have an open process for maintenance. We also note that software vendors are mostly not included in the intended group of users of the measurement results. A revision of methods and their maintenance processes can increase their accountability and ena…
Economie assessments on the use of wired and wireless recharging systems in Italian and European market
2017
The conductive charging method for the electric vehicles is the most widespread, since it is the simplest and has higher returns. In the last years, alternative charging technologies have been investigated. Between these wireless charging systems have been large diffusion and have been commercialized by some manufacturer. Wireless charging systems for electric vehicles have some advantages respect the wired ones, not obliging the user to connect physically the vehicle to the electric charging station. Assuming the efficiency declared by the manufacturer of wireless systems the authors, in this paper, estimate the maximum cost that wireless recharging systems can have to be, however, more fa…