The Experts below are selected from a list of 266238 Experts worldwide ranked by ideXlab platform
T Tison - One of the best experts on this subject based on the ideXlab platform.
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a global strategy for the stability analysis of friction induced vibration problem with parameter variations
Mechanical Systems and Signal Processing, 2017Co-Authors: Hai Quan Do, Franck Massa, T Tison, B LallemandAbstract:Abstract This paper presents a Numerical strategy to reanalyze the modified frequency stability analysis of friction induced vibration problem. The stability analysis of a mechanical system relies on several coupling steps, namely a non-linear static analysis followed by linear and complex eigenvalue problems. We thus propose a Numerical strategy to perform more rapidly multiple complex eigenvalue analyses. This strategy couples three methods namely, Fuzzy Logic Controllers to manage frictional contact problem, homotopy developments and projection techniques to reanalyze the projection matrices and component mode synthesis to calculate the modified eigensolutions. A Numerical Application is performed to highlight the efficiency of the strategy and a discussion is proposed in terms of precision and computational time.
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multi level homotopy perturbation and projection techniques for the reanalysis of quadratic eigenvalue problems the Application of stability analysis
Mechanical Systems and Signal Processing, 2015Co-Authors: Franck Massa, T Tison, B LallemandAbstract:Abstract Complex eigenvalue analysis is widely used to investigate the stability of a dynamical system with frictional contact. For finite element models, iterative solvers are needed to precisely calculate complex modes and eigenvalues. However, in cases such as reanalysis studies, optimization or uncertainty propagation processes, computational cost can quickly become too time consuming. For multiple samplings, two methods combining homotopy perturbation and projection techniques are proposed for the reanalysis of quadratic eigenvalue problems. To highlight the efficiency of the proposed methods, a complete Numerical Application including nominal and perturbed solution calculations, coalescence graph and parametric analysis, is performed. The precision of results and computational time are compared with those obtained using commercial software.
Adiel Teixeira De Almeida - One of the best experts on this subject based on the ideXlab platform.
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assessment of synergies for selecting a project portfolio in the petroleum industry based on a multi attribute utility function
Journal of Petroleum Science and Engineering, 2015Co-Authors: Yuri Gama Lopes, Adiel Teixeira De AlmeidaAbstract:Abstract The oil and gas industry engages in risk activities: companies in this line of business are routinely faced with decision making situations under risk and uncertainty. This article focuses on evaluating Exploration and Production (E&P) projects which are in the development phase. Three key aspects that should be considered in selecting projects that aim to develop the production of oil and gas are as follows: the stochastic and multi-objective nature of this decision context, an assessment of a project׳s synergies, and the influence that these aspects have on the decision maker׳s preference structure. The contribution of this paper is to put forward a multi-attribute decision model to aid selecting oil and gas development projects in order to assign them to an appropriate portfolio. For this purpose, the proposed model takes into account the aspects described above. A multi-attribute decision model is proposed to aid selecting such projects and a Numerical Application is conducted. Questions related to assessing uncertainty and considering multiple objectives are tackled within the axiomatic structures of MAUT (Multi-attribute Utility Theory). Assessing synergies between projects is particularized in the context of selecting an E&P project portfolio and, in addition, the consequences of these synergistic considerations in value- or utility-based decision models are discussed. Finally, a Numerical Application is set out in order to visualize and discuss the steps of the model, as well as to demonstrate and discuss its usefulness and some practical issues that arise.
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A multicriteria model for risk sorting of natural gas pipelines based on ELECTRE TRI integrating Utility Theory
European Journal of Operational Research, 2010Co-Authors: Anderson J. Brito, Adiel Teixeira De Almeida, Caroline Maria De Miranda MotaAbstract:This paper proposes a multicriteria model for assessing risk in natural gas pipelines, and for classifying sections of pipeline into risk categories. The model integrates Utility Theory and the ELECTRE TRI method. It aims to help transmission and distribution companies, when engaged in risk management and decision-making, to consider the multiple dimensions of risk that may arise from pipeline accidents. Pipeline hazard scenarios are presented, and it is argued that the assessment of risk in natural gas pipelines should not be based solely on probabilities of human fatalities, but should involve a wider perspective that simultaneously takes into consideration the human, environmental and financial dimensions of impacts of pipeline accidents. Finally, in order to verify the effectiveness of the model set out, a Numerical Application based on a real case study is presented.
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multicriteria decision model for outsourcing contracts selection based on utility function and electre method
Computers & Operations Research, 2007Co-Authors: Adiel Teixeira De AlmeidaAbstract:An outsourcing contract problem has been analyzed. This is a typical problem when dealing with outsourcing vendor selection. For each alternative of an outsourcing contract there is an evaluation of both cost and quality of service. The latter may include probabilistic delivery time and confidence in quality commitment. The decision-maker takes into account multicriteria evaluation through ELECTRE method. Besides, each criterion is evaluated through a utility function. The model integrates both approaches to indicate a contract proposal. This paper presents the formulation for the decision model and a Numerical Application to illustrate the use of the model.
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multicriteria modelling of repair contract based on utility and electre i method with dependability and service quality criteria
Annals of Operations Research, 2005Co-Authors: Adiel Teixeira De AlmeidaAbstract:A DM faces a choice among several alternatives of repair contract for a system. Each alternative of a repair contract implies specific results regarding the following characteristics or criteria: response time, quality service, dependability and related cost. This problem has been analysed through a multicriteria decision model. The model is based on the ELECTRE method combined with utility functions. Main theoretical aspects and practical implications are presented, including a Numerical Application.
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multicriteria decision making on maintenance spares and contracts planning
European Journal of Operational Research, 2001Co-Authors: Adiel Teixeira De AlmeidaAbstract:Abstract The competitiveness of an industrial system is directly related to decision making in areas of product support logistics, such as the maintenance area. Multicriteria decision making takes into account various aspects associated with competitiveness of the system. This paper presents multicriteria decision models for two maintenance problems: repair contract selection and spares provisioning. In the repair contract problem the model incorporates consequences modelled through a multiattribute utility function. These consequences consist of contract cost and system performance, represented by the system interruption time. Two criteria (risk and cost) are combined through a multiattribute utility function in the spares provisioning decision model. This paper presents the formulation and derivations for both models and the Numerical Application illustrates the use of models including sensitivity analysis.
B Lallemand - One of the best experts on this subject based on the ideXlab platform.
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a global strategy for the stability analysis of friction induced vibration problem with parameter variations
Mechanical Systems and Signal Processing, 2017Co-Authors: Hai Quan Do, Franck Massa, T Tison, B LallemandAbstract:Abstract This paper presents a Numerical strategy to reanalyze the modified frequency stability analysis of friction induced vibration problem. The stability analysis of a mechanical system relies on several coupling steps, namely a non-linear static analysis followed by linear and complex eigenvalue problems. We thus propose a Numerical strategy to perform more rapidly multiple complex eigenvalue analyses. This strategy couples three methods namely, Fuzzy Logic Controllers to manage frictional contact problem, homotopy developments and projection techniques to reanalyze the projection matrices and component mode synthesis to calculate the modified eigensolutions. A Numerical Application is performed to highlight the efficiency of the strategy and a discussion is proposed in terms of precision and computational time.
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multi level homotopy perturbation and projection techniques for the reanalysis of quadratic eigenvalue problems the Application of stability analysis
Mechanical Systems and Signal Processing, 2015Co-Authors: Franck Massa, T Tison, B LallemandAbstract:Abstract Complex eigenvalue analysis is widely used to investigate the stability of a dynamical system with frictional contact. For finite element models, iterative solvers are needed to precisely calculate complex modes and eigenvalues. However, in cases such as reanalysis studies, optimization or uncertainty propagation processes, computational cost can quickly become too time consuming. For multiple samplings, two methods combining homotopy perturbation and projection techniques are proposed for the reanalysis of quadratic eigenvalue problems. To highlight the efficiency of the proposed methods, a complete Numerical Application including nominal and perturbed solution calculations, coalescence graph and parametric analysis, is performed. The precision of results and computational time are compared with those obtained using commercial software.
François Dufour - One of the best experts on this subject based on the ideXlab platform.
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Numerical Approximations for Discounted Continuous Time Markov Decision Processes
2019Co-Authors: François Dufour, Tomás Prieto-rumeauAbstract:This paper deals with a continuous-time Markov decision process M, with Borel state and action spaces, under the total expected discounted cost optimality criterion. By suitably approximating an underlying probability measure with a measure with finite support and by discretizing the action sets of the control model, we can construct a finite state and action space Markov decision process that approximates M and that can be solved explicitly. We can derive bounds on the approximation error of the optimal discounted cost function; such bounds are written in terms of Wasserstein and Hausdorff distances. We show a Numerical Application to a queueing problem.
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finite linear programming approximations of constrained discounted markov decision processes
Siam Journal on Control and Optimization, 2013Co-Authors: François Dufour, Tomas PrietorumeauAbstract:We consider a Markov decision process (MDP) with constraints under the total expected discounted cost optimality criterion. We are interested in proposing approximation methods of the optimal value of this constrained MDP. To this end, starting from the linear programming (LP) formulation of the constrained MDP (on an infinite-dimensional space of measures), we propose a finite state approximation of this LP problem. This is achieved by suitably approximating a probability measure underlying the random transitions of the dynamics of the system. Explicit convergence orders of the approximations of the optimal constrained cost are obtained. By exploiting convexity properties of the class of relaxed controls, we reduce the LP formulation of the constrained MDP to a finite-dimensional static optimization problem that can be used to obtain explicit Numerical approximations of the corresponding optimal constrained cost. A Numerical Application illustrates our theoretical results.
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approximation of markov decision processes with general state space
Journal of Mathematical Analysis and Applications, 2012Co-Authors: François Dufour, Tomas PrietorumeauAbstract:Abstract We deal with a discrete-time finite horizon Markov decision process with locally compact Borel state and action spaces, and possibly unbounded cost function. Based on Lipschitz continuity of the elements of the control model, we propose a state and action discretization procedure for approximating the optimal value function and an optimal policy of the original control model. We provide explicit bounds on the approximation errors. Our results are illustrated by a Numerical Application to a fisheries management problem.
Franck Massa - One of the best experts on this subject based on the ideXlab platform.
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a global strategy for the stability analysis of friction induced vibration problem with parameter variations
Mechanical Systems and Signal Processing, 2017Co-Authors: Hai Quan Do, Franck Massa, T Tison, B LallemandAbstract:Abstract This paper presents a Numerical strategy to reanalyze the modified frequency stability analysis of friction induced vibration problem. The stability analysis of a mechanical system relies on several coupling steps, namely a non-linear static analysis followed by linear and complex eigenvalue problems. We thus propose a Numerical strategy to perform more rapidly multiple complex eigenvalue analyses. This strategy couples three methods namely, Fuzzy Logic Controllers to manage frictional contact problem, homotopy developments and projection techniques to reanalyze the projection matrices and component mode synthesis to calculate the modified eigensolutions. A Numerical Application is performed to highlight the efficiency of the strategy and a discussion is proposed in terms of precision and computational time.
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multi level homotopy perturbation and projection techniques for the reanalysis of quadratic eigenvalue problems the Application of stability analysis
Mechanical Systems and Signal Processing, 2015Co-Authors: Franck Massa, T Tison, B LallemandAbstract:Abstract Complex eigenvalue analysis is widely used to investigate the stability of a dynamical system with frictional contact. For finite element models, iterative solvers are needed to precisely calculate complex modes and eigenvalues. However, in cases such as reanalysis studies, optimization or uncertainty propagation processes, computational cost can quickly become too time consuming. For multiple samplings, two methods combining homotopy perturbation and projection techniques are proposed for the reanalysis of quadratic eigenvalue problems. To highlight the efficiency of the proposed methods, a complete Numerical Application including nominal and perturbed solution calculations, coalescence graph and parametric analysis, is performed. The precision of results and computational time are compared with those obtained using commercial software.
