Search results for "Liability"
showing 10 items of 1754 documents
Optimal Selection of Maintenance Actions on a Multi-Component System
2010
The research aims to single out the maintenance actions to perform on a series arranged components system each one constituted by elements in parallel and maintained only during some planned stops. The considered system has to periodically carry out missions during which the system failure is a critical event for their own success. That being so, the faced problem is here to assure the maximum reliability level up to the next planned stop. For this reason an exact algorithm is proposed in order to individuate the set of components on which performing maintenance actions and for each of them determining the number of elements that must be maintained so as the maximum reliability level is ach…
Robust Maintenance Scheduling for Reliability Maximization
2009
The present paper aims to single out the maintenance actions to perform on a system constrained to be maintained only during some planned stops. Since system failure implies costs and risks for people and/or the environment, then it is necessary to minimize the probability of its occurrence. Thus, maintenance actions need to maximize the system reliability up to the next planned stop, in respect to some constraint. The originality of the problem discussed in the present paper lies in considering reliability values affected with uncertainty within a range of vagueness. Consequently, a further problem is added to the constrained reliability maximization, that is the search for a robust soluti…
Selection of Series System Components to Maximize Reliability
2010
The paper tackles the problem of maximizing the reliability of a series system by an opportune choice of components. Each type of component must be selected among the available alternatives for that component whereas a fixed amount of budget can not be overcome. The problem can be formulated by a binary non linear programming model and it is equivalent to a knapsack problem with multiple-choice constraints, well known to be NP-hard. An exact algorithm is proposed for solving large dimension problems to the optimum in a short time. The algorithm efficiency is finally compared with the recent heuristics proposed in literature to approach the same problem.
Human reliability analysis to support the development of a software project
2017
The Human Reliability Analysis (HRA) is considered as a useful tool in predicting and quantifying the occurrence of human errors during the execution of a specific task. With this recognition, the present paper firstly aims at discussing the support given by HRA methodologies to the fault risk evaluation. Then, the Technique for Human Error Rate Prediction (THERP) is suggested to evaluate the success probability of a software development project.
a diagnostic and prognostic system to enhance the operational readiness of mission critical systems
2009
Maintenance Planning For The Reliability Maximization In A Large System With Vagueness In The Reliability Values Of Some Components
2015
This paper tackles the problem to single out the maintenance actions to be executed on a production system during the planned stop of given length. In detail, from a reliability viewpoint the system is assimilated as a series-parallel multi-component system and the maintenance actions need to maximize the system reliability up to the next planned stop. Moreover, it is assumed that some components reliability values are affected by vagueness within a given range. To solve the considered problem, an exact dynamic programming algorithm suitable to quickly point out the maintenance scheduling is developed and, moreover, it is formulated a proper parameter able to express the robustness of the o…
Reliability and Fabrication of Molds for Nanoimprinting
2010
During the last decade there has been a growing attention to nanoscaled materials and to the related technologies to produce them. The problems to overcome in the manufacturing of these kinds of items increase dramatically on decreasing the dimension of the devices. In this sense, the scientific research has been strongly stimulated to try to improve and optimize all the critical issues. One of the most attractive fields in nanomanufacturing is related to nanoimprinting, i.e. to the possibility to transfer a nanoscaled pattern from a mold to another substrate. In this technology, among the others, there are two main critical steps: the preparation of a good mold and the use of a correct rel…
Vibration-based identification of mechanical properties of orthotropic arbitrarily shaped plates: Numerical and experimental assessment
2018
Abstract An innovative procedure is introduced for the identification of the mechanical parameters of orthotropic plates of arbitrary shape, under various boundary conditions, based on vibration data. The method employs a combination of a convenient Rayleigh-Ritz approach and Particle-Swarm Optimization to estimate elastic constants of the orthotropic material in a straightforward manner, without requiring computationally demanding iterative Finite Element analyses. Specifically, the pb-2 Rayleigh-Ritz procedure is extended and applied to deal with orthotropic plates, simplifying the approach to more easily treat generic plate shapes, taking advantage of the Green's theorem. The method is t…
Electrical characterization of low power CIGSSe photovoltaic modules
2015
This paper presents the electrical characterization of low power CIGSSe photovoltaic (PV) modules. Such investigation is achieved to perform a comparison of their performances with conventional silicon PV modules. For this purpose, a test bench, suitable for the characterization of both traditional and innovative low power modules, has been set-up and experimental results are accurately described and discussed.
Dynamic thermal rating for overhead lines: Self-adaptive protection device
2013
The increase in the consumption of electricity, the stringent environmental restrictions and the need to keep costs, make ever more meaningful the need for a flexible operation of existing overhead lines. This paper studies the possibility to use a dynamic thermal rating for overhead line starting from the analysis of the mathematical model and the ability of the latter to reflect the temperature of an overhead conductor in different ambient condition; then it simulates the thermal behaviour of a conductor both in steady state and dynamic one. Finally the paper shows a method for a self-adaptive thermal protection system.