204 resultados para Inverse problems

em Queensland University of Technology - ePrints Archive


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This paper compares the performances of two different optimisation techniques for solving inverse problems; the first one deals with the Hierarchical Asynchronous Parallel Evolutionary Algorithms software (HAPEA) and the second is implemented with a game strategy named Nash-EA. The HAPEA software is based on a hierarchical topology and asynchronous parallel computation. The Nash-EA methodology is introduced as a distributed virtual game and consists of splitting the wing design variables - aerofoil sections - supervised by players optimising their own strategy. The HAPEA and Nash-EA software methodologies are applied to a single objective aerodynamic ONERA M6 wing reconstruction. Numerical results from the two approaches are compared in terms of the quality of model and computational expense and demonstrate the superiority of the distributed Nash-EA methodology in a parallel environment for a similar design quality.

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Inverse problems based on using experimental data to estimate unknown parameters of a system often arise in biological and chaotic systems. In this paper, we consider parameter estimation in systems biology involving linear and non-linear complex dynamical models, including the Michaelis–Menten enzyme kinetic system, a dynamical model of competence induction in Bacillus subtilis bacteria and a model of feedback bypass in B. subtilis bacteria. We propose some novel techniques for inverse problems. Firstly, we establish an approximation of a non-linear differential algebraic equation that corresponds to the given biological systems. Secondly, we use the Picard contraction mapping, collage methods and numerical integration techniques to convert the parameter estimation into a minimization problem of the parameters. We propose two optimization techniques: a grid approximation method and a modified hybrid Nelder–Mead simplex search and particle swarm optimization (MH-NMSS-PSO) for non-linear parameter estimation. The two techniques are used for parameter estimation in a model of competence induction in B. subtilis bacteria with noisy data. The MH-NMSS-PSO scheme is applied to a dynamical model of competence induction in B. subtilis bacteria based on experimental data and the model for feedback bypass. Numerical results demonstrate the effectiveness of our approach.

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Abstract—Computational Intelligence Systems (CIS) is one of advanced softwares. CIS has been important position for solving single-objective / reverse / inverse and multi-objective design problems in engineering. The paper hybridise a CIS for optimisation with the concept of Nash-Equilibrium as an optimisation pre-conditioner to accelerate the optimisation process. The hybridised CIS (Hybrid Intelligence System) coupled to the Finite Element Analysis (FEA) tool and one type of Computer Aided Design(CAD) system; GiD is applied to solve an inverse engineering design problem; reconstruction of High Lift Systems (HLS). Numerical results obtained by the hybridised CIS are compared to the results obtained by the original CIS. The benefits of using the concept of Nash-Equilibrium are clearly demonstrated in terms of solution accuracy and optimisation efficiency.

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This paper uses data from a large national project on student-working to examine problems and challenges for school students working in part-time jobs. While literature has identified some potential problems and challenges, and some potential difficulties can be extrapolated from the nature of a young teenage workforce and the nature of the workplaces, these were largely absent in the two companies researched because the companies already had policies in place that addressed the potential problems. Some suggestions are made about how problems and challenges could be avoided in a wider range of adolescent workplaces.

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Under the Alien Tort Statute United States of America (“America”) Federal Courts have the jurisdiction to hear claims for civil wrongs, committed against non-American citizens, which were perpetrated outside America’s national borders. The operation of this law has confronted American Federal Courts with difficulties on how to manage conflicts between American executive foreign policy and judicial interpretations of international law. Courts began to pass judgment over conduct which was approved by foreign governments. Then in 2005 the American Supreme Court wound back the scope of the Alien Tort Statute. This article will review the problems with the expansion of the Alien Tort Statute and the reasons for its subsequent narrowing.

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Fair Work Australia is to provide the institutional framework for the Australian industrial relations system from January 2010. Its creation provides the opportunity to improve minimum labour standards’ enforcement in Australia. However, the experience of the past must be appreciated and traditional assumptions about the operation of the Australian enforcement system discarded if the new institution is to be effective in its role. This paper focuses on the role of unions in enforcement as well as institutional location issues to expose a number of central enforcement problems that those seeking to establish new systems and processes should consider. A number of recommendations in respect of the structure of Fair Work Australia and the continuing role of unions are suggested.