Dissertations / Theses on the topic 'Evolutionary structural optimisation'
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Proos, Kaarel. "Evolutionary structural optimisation as a robust and reliable design tool." Connect to full text, 2002. http://hdl.handle.net/2123/519.
Full textTitle from title screen (viewed Apr. 28, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Aeronautical, Mechatronic and Mechanical Engineering. Includes bibliographical references. Also available in print form.
Proos, Kaarel Andres. "Evolutionary structural optimisation as a robust and reliable design tool." Thesis, The University of Sydney, 2002. http://hdl.handle.net/2123/519.
Full textProos, Kaarel Andres. "Evolutionary structural optimisation as a robust and reliable design tool." University of Sydney. Aerospace, 2002. http://hdl.handle.net/2123/519.
Full textWong, Kin Ming. "Evolutionary structural form optimisation for lateral stiffness design of tall buildings /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20WONGK.
Full textCervera, Eva. "Evolutionary structural optimisation based on boundary element representation of B-spline geometry." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/2004/.
Full textKelly, Liam. "Reducing design time : the impact of evolutionary structural optimisation on structural trade studies during preliminary design." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/380508/.
Full textBrodie, Robert Neil. "Development of controllability and robustness methodologies for Bi-directional Evolutionary Structural Optimisation (BESO)." Thesis, University of Leeds, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486156.
Full textAgyei, Eugene Osei. "Groundwater modeling and management using the finite element method and evolutionary optimisation techniques /." Title page, synopsis and contents only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09pha284.pdf.
Full textEbenhöh, Oliver. "Structural analysis of metabolic networks." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2003. http://dx.doi.org/10.18452/14853.
Full textIn the present thesis two models are presented which study the structural design of metabolic systems. The investigation is based on the hypothesis that present day metabolic systems are the result of an evolutionary development governed by mutation mechanisms and natural selection principles. Therefore, it can be assumed that these parameters have reached, during the course of their evolution, values which imply certain optimal properties with respect to their biological function. The first model concerns the structural design of ATP and NADH producing systems such as glycolysis and the citric acid cycle. A method is presented to describe hypothetical, chemically feasible, alternative pathways. We analyse these pathways with respect to their capability to efficiently produce ATP. It is shown that most of the possible pathways result in a very low ATP production rate and that the very efficient pathways share common structural properties. Optimisation with respect to the ATP production rate is performed by an evolutionary algorithm. The following results of our analysis are in close correspondence to the real design of glycolysis and the TCA cycle: (i) In all efficient pathways the ATP consuming reactions are located near the beginning. (ii) In all efficient pathways NADH producing reactions as well as ATP producing reactions are located near the end. (iii) The number of NADH molecules produced by the consumption of one energy-rich molecule (glucose) amounts to four in all efficient pathways. In the second model complete sets of metabolic networks are constructed starting from a limited set of reactions describing changes in the carbon skeleton of biochemical compounds. Elementary networks are defined by the condition that a specific chemical conversion can be performed by a set of given reactions and that this ability will be lost by elimination of any of these reactions. Transitions between networks and mutations of networks are defined by exchanges of single reactions. Different mutations exist such as gain or loss of function mutations and neutral mutations. Based on these mutations neighbourhood relations between networks are established which are described in a graph theoretical way. Basic properties of these graphs are determined such as diameter, connectedness, distance distribution of pairs of vertices. A concept is developed to quantify the robustness of networks against changes in their stoichiometry where we distinguish between strong and weak robustness. Evolutionary algorithms are applied to study the development of network populations under constant and time dependent environmental conditions. It is shown that the populations evolve toward clusters of networks performing a common function and which are closely neighboured. Under changing environmental conditions multifunctional networks prove to be optimal and will be selected.
Damp, Lloyd Hollis. "Multi-Objective and Multidisciplinary Design Optimisation of Unmanned Aerial Vehicle Systems using Hierarchical Asynchronous Parallel Multi-Objective Evolutionary Algorithms." Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/1858.
Full textDamp, Lloyd Hollis. "Multi-Objective and Multidisciplinary Design Optimisation of Unmanned Aerial Vehicle Systems using Hierarchical Asynchronous Parallel Multi-Objective Evolutionary Algorithms." University of Sydney, 2007. http://hdl.handle.net/2123/1858.
Full textThe overall objective of this research was to realise the practical application of Hierarchical Asynchronous Parallel Evolutionary Algorithms for Multi-objective and Multidisciplinary Design Optimisation (MDO) of UAV Systems using high fidelity analysis tools. The research looked at the assumed aerodynamics and structures of two production UAV wings and attempted to optimise these wings in isolation to the rest of the vehicle. The project was sponsored by the Asian Office of the Air Force Office of Scientific Research under contract number AOARD-044078. The two vehicles wings which were optimised were based upon assumptions made on the Northrop Grumman Global Hawk (GH), a High Altitude Long Endurance (HALE) vehicle, and the General Atomics Altair (Altair), Medium Altitude Long Endurance (MALE) vehicle. The optimisations for both vehicles were performed at cruise altitude with MTOW minus 5% fuel and a 2.5g load case. The GH was assumed to use NASA LRN 1015 aerofoil at the root, crank and tip locations with five spars and ten ribs. The Altair was assumed to use the NACA4415 aerofoil at all three locations with two internal spars and ten ribs. Both models used a parabolic variation of spar, rib and wing skin thickness as a function of span, and in the case of the wing skin thickness, also chord. The work was carried out by integrating the current University of Sydney designed Evolutionary Optimiser (HAPMOEA) with Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) tools. The variable values computed by HAPMOEA were subjected to structural and aerodynamic analysis. The aerodynamic analysis computed the pressure loads using a Boeing developed Morino class panel method code named PANAIR. These aerodynamic results were coupled to a FEA code, MSC.Nastran® and the strain and displacement of the wings computed. The fitness of each wing was computed from the outputs of each program. In total, 48 design variables were defined to describe both the structural and aerodynamic properties of the wings subject to several constraints. These variables allowed for the alteration of the three aerofoil sections describing the root, crank and tip sections. They also described the internal structure of the wings allowing for variable flexibility within the wing box structure. These design variables were manipulated by the optimiser such that two fitness functions were minimised. The fitness functions were the overall mass of the simulated wing box structure and the inverse of the lift to drag ratio. Furthermore, six penalty functions were added to further penalise genetically inferior wings and force the optimiser to not pass on their genetic material. The results indicate that given the initial assumptions made on all the aerodynamic and structural properties of the HALE and MALE wings, a reduction in mass and drag is possible through the use of the HAPMOEA code. The code was terminated after 300 evaluations of each hierarchical level due to plateau effects. These evolutionary optimisation results could be further refined through a gradient based optimiser if required. Even though a reduced number of evaluations were performed, weight and drag reductions of between 10 and 20 percent were easy to achieve and indicate that the wings of both vehicles can be optimised.
Tchvagha, Zeine Ahmed. "Contribution à l’optimisation multi-objectifs sous contraintes : applications à la mécanique des structures." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMIR13/document.
Full textThe objective of this thesis is the development of multi-objective optimization methods for solving mechanical design problems. Indeed, most of the real problems in the field of mechanical structures have several objectives that are often antagonistic. For example, it is about designing structures by optimizing their weight, their size, and their production costs. The goal of multi-objective optimization methods is the search for compromise solutions between objectives given the impossibility to satisfy all simultaneously. Metaheuristics are optimization methods capable of solving multi-objective optimization problems in a reasonable calculation time without guaranteeing the optimality of the solution (s). In recent years, these algorithms have been successfully applied to solve the problem of structural mechanics. In this thesis, two metaheuristics have been developed for the resolution of multi-objective optimization problems in general and of mechanical structures design in particular. The first algorithm called MOBSA used the crossover and mutation operators of the BSA algorithm. The second one named NNIA+X is a hybridization of an immune algorithm and three crossover inspired by the original crossover operator of the BSA algorithm. To evaluate the effectiveness and efficiency of these two algorithms, tests on some problems in literature have been made with a comparison with algorithms well known in the field of multi-objective optimization. The comparison results using metrics widely used in the literature have shown that our two algorithms can compete with their predecessors
Gao, Huanhuan. "Categorical structural optimization : methods and applications." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2471/document.
Full textThe thesis concentrates on a methodological research on categorical structural optimizationby means of manifold learning. The main difficulty of handling the categorical optimization problems lies in the description of the categorical variables: they are presented in a category and do not have any orders. Thus the treatment of the design space is a key issue. In this thesis, the non-ordinal categorical variables are treated as multi-dimensional discrete variables, thus the dimensionality of corresponding design space becomes high. In order to reduce the dimensionality, the manifold learning techniques are introduced to find the intrinsic dimensionality and map the original design space to a reduced-order space. The mechanisms of both linear and non-linear manifold learning techniques are firstly studied. Then numerical examples are tested to compare the performance of manifold learning techniques mentioned above. It is found that the PCA and MDS can only deal with linear or globally approximately linear cases. Isomap preserves the geodesic distances for non-linear manifold however, its time consuming is the most. LLE preserves the neighbour weights and can yield good results in a short time. KPCA works like a non-linear classifier and we proves why it cannot preserve distances or angles in some cases. Based on the reduced-order representation obtained by Isomap, the graph-based evolutionary crossover and mutation operators are proposed to deal with categorical structural optimization problems, including the design of dome, six-story rigid frame and dame-like structures. The results show that the proposed graph-based evolutionary approach constructed on the reduced-order space performs more efficiently than traditional methods including simplex approach or evolutionary approach without reduced-order space. In chapter 5, the LLE is applied to reduce the data dimensionality and a polynomial interpolation helps to construct the responding surface from lower dimensional representation to original data. Then the continuous search method of moving asymptotes is executed and yields a competitively good but inadmissible solution within only a few of iteration numbers. Then in the second stage, a discrete search strategy is proposed to find out better solutions based on a neighbour search. The ten-bar truss and dome structural design problems are tested to show the validity of the method. In the end, this method is compared to the Simulated Annealing algorithm and Covariance Matrix Adaptation Evolutionary Strategy, showing its better optimization efficiency. In chapter 6, in order to deal with the case in which the categorical design instances are distributed on several manifolds, we propose a k-manifolds learning method based on the Weighted Principal Component Analysis. And the obtained manifolds are integrated in the lower dimensional design space. Then the method introduced in chapter 4 is applied to solve the ten-bar truss, the dome and the dame-like structural design problems
Filomeno, Coelho Rajan. "Multicriteria optimization with expert rules for mechanical design." Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211184.
Full textConsequently, to solve these problems, the most wide-spread meta-heuristic methods are evolutionary algorithms (EAs), which work as follows: the best individuals among an initial population of randomly generated potential solutions are favoured and com-bined (by specific operators like crossover and mutation) in order to create potentially better individuals at the next generation. The creation of new generations is repeated till the convergence is reached. The ability of EAs to explore widely the design space is useful to solve single-objective unconstrained optimization problems, because it gener-ally prevents from getting trapped into a local optimum, but it is also well known that they do not perform very efficiently in the presence of constraints. Furthermore, in many industrial applications, multiple objectives are pursued together.
Therefore, to take into account the constrained and multicriteria aspects of optimization problems in EAs, a new method called PAMUC (Preferences Applied to MUltiobjectiv-ity and Constraints) has been proposed in this dissertation. First the user has to assign weights to the m objectives. Then, an additional objective function is built by linearly aggregating the normalized constraints. Finally, a multicriteria decision aid method, PROMETHEE II, is used in order to rank the individuals of the population following the m+1 objectives.
PAMUC has been validated on standard multiobjective test cases, as well as on the pa-rametrical optimization of the purge valve and the feed valve of the Vinci engine, both designed by Techspace Aero for launcher Ariane 5.
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Doctorat en sciences appliquées
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Gladwin, Daniel Thomas. "Automated Control Structure Design and optimisation using Evolutionary Computing." Thesis, University of Sheffield, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522000.
Full textKatzen, Jeffrey Marc. "Optimisation of a tree structured centralized data network using an evolutionary algorithm." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/21169.
Full textOaken, David R. "Optimisation of definition structures & parameter values in process algebra models using evolutionary computation." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/21206.
Full textLasseigne, Alexis. "Optimization of variable-thickness composite structures. Application to a CROR blade." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM006/document.
Full textThis thesis deals with the optimal design of variable-thickness laminated composite structures. The stacking variables define a combinatorial optimization problem and large decision spaces which are potentially multimodal. Stochastic optimization algorithms allow solving this type of problem and allow taking advantage from the performance and the anisotropic nature of unidirectional composite plies to lighten laminated composite structures.The purpose of this study is twofold: (i) developing an optimization algorithm dedicated to variable-thickness laminated composites and (ii) assessing the potential of laminated composites in influencing the aerodynamic performances of a composite CROR blade.Firstly, an evolutionary algorithm is specialized in order to optimize layup tables and handle a set of design guidelines which is representative of industrial practices. In this purpose, a specific encoding of the solutions is suggested and specialized variation operators are developed.Secondly, the algorithm is enriched with a guiding technique based on the exploitation of an auxiliary space in order to improve its efficiency and to include further composites-related knowledge for the resolution of the problem.Finally, the method is applied for the design of a reduced-scale composite CROR blade intended for wind-tunnel testing. Beforehand, iterative processes are implemented to estimate the shape of the non-operating blade and the stress state within the operating blade
Frechard, Jonathan. "Systèmes d'entraînement de bandes flexibles : optimisation multicritère des performances dynamiques par approche évolutionnaire." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD015/document.
Full textThe design of roll-to-roll systems is studied for several years. This kind of system is very common in industry because the wound roll packaging simplify the treatment of material such as paper, cardboard, polymers, metal ... The studied systems have a high number of difficulties: they are large scale systems, a high coupling between physical values exists and several parameters are time dependent. The classical optimisation method consists in considering separately each subsystem without taking into account interactions. Moreover, the classical optimisation is made for each scientific field. A new approach is developed and applied to controller synthesis: the controllers are synthesized considering the global system with parametric uncertainties. The optimal choice of the master roller position and the technology used to control web tension are then studied
Mereuta, Alina. "Smart web accessibility platform : dichromacy compensation and web page structure improvement." Thesis, Tours, 2014. http://www.theses.fr/2014TOUR4032/document.
Full textThis thesis works are focused on enhancing web accessibility for users with visual disabilities using tools integrated within the SmartWeb Accessibility Platform (SWAP). After a synthesis on accessibility, SWAP is presented. Our first contribution consists in reducing the contrast loss for textual information in web pages for dichromat users while maintaining the author’s intentions conveyed by colors. The contrast compensation problem is reduced at minimizing a fitness function which depends on the original colors and the relationships between them. The interest and efficiency of three methods (mass-spring system, CMA-ES, API) are assessed on two datasets (real and artificial). The second contribution focuses on enhancing web page structure for screen reader users in order to overcome the effect of contents’linearization. Using heuristics and machine learning techniques, the main zones of the page are identified. The page structure can be enhanced using ARIA statements and access links to improve zone identification by screen readers
Mouelhi-Chibani, Wiem. "Apprentissage autonome de réseaux de neurones pour le pilotage en temps réel des systèmes de production basé sur l'optimisation via simulation." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2009. http://tel.archives-ouvertes.fr/tel-00725259.
Full textManickarajah, Dhayanthi. "Optimum design of structures with stability constraints using the evolutionary optimisation method." Thesis, 1998. https://vuir.vu.edu.au/15258/.
Full textYang, Xiaoying. "Evolutionary methods for topology optimisation of continuum structures: static and dynamic problems." Thesis, 2002. https://vuir.vu.edu.au/15736/.
Full textYang, Xiaoying. "Bi-directional evolutionary method for stiffness and displacement optimisation." Thesis, 1999. https://vuir.vu.edu.au/18230/.
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