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Relevant bibliographies by topics / Optimisation by simplex method

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Academic literature on the topic 'Optimisation by simplex method'

Author: Grafiati

Published: 24 April 2022

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Journal articles on the topic "Optimisation by simplex method"

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Bellezza, Ivo. "Optimisation of landfill volume by the simplex method." Engineering Computations 21, no. 1 (2004): 53–65. http://dx.doi.org/10.1108/02644400410511837.

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Clayton, R. P., and R. F. Martinez-Botas. "Application of generic algorithms in aerodynamic optimisation design procedures." Aeronautical Journal 108, no. 1090 (2004): 611–20. http://dx.doi.org/10.1017/s0001924000000440.

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AbstractDirect optimisation techniques using different methods are presented and compared for the solution of two common flows: a two dimensional diffuser and a drag minimisation problem of a fixed area body. The methods studied are a truncated Newton algorithm (gradient method), a simplex approach (direct search method) and a genetic algorithm (stochastic method). The diffuser problem has a known solution supported by experimental data, it has one design performance measure (the pressure coefficient) and two design variables. The fixed area body also has one performance measure (the drag coefficient), but this time there are four design variables; no experimental data is available, this computation is performed to assess the speed/progression of solution.In all cases the direct search approach (simplex method) required significantly smaller number of evaluations than the generic algorithm method. The simplest approach, the gradient method (Newton) performed equally to the simplex approach for the diffuser problem but it was unable to provide a solution to the four-variable problem of a fixed area body drag minimisation. The level of robustness obtained by the use of generic algorithm is in principle superior to the other methods, but a large price in terms of evaluations has to be paid.

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Siemek, Jakub, and Jerzy Stopa. "Optimisation of the wells placement in gas reservoirs using SIMPLEX method." Journal of Petroleum Science and Engineering 54, no. 3-4 (2006): 164–72. http://dx.doi.org/10.1016/j.petrol.2006.08.013.

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Zde Zar, U. "Simple Optimisation Method in Mammography." Radiation Protection Dosimetry 90, no. 1 (2000): 221–23. http://dx.doi.org/10.1093/oxfordjournals.rpd.a033124.

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Da Costa, Julyane Karolyne Teixeira, Karina Gomes Angilelli, Kelly Roberta Spacino, Elisangela Tavares Da Silva, Livia Ramazzoti Chanan Silva, and Dionisio Borsato. "APPLICATION OF THE MULTIRESPONSE OPTIMISATION SIMPLEX METHOD TO THE BIODIESEL - B100 OBTAINING PROCESS." Semina: Ciências Exatas e Tecnológicas 37, no. 1 (2016): 107. http://dx.doi.org/10.5433/1679-0375.2016v37n1p107.

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<p>O processo de obtenção de biodiesel B100, a partir da transesterificação em meio básico, de uma mistura de óleo vegetal e gordura animal foi otimizado utilizando o método simplex supermodificado. Para otimização simultânea foram usados como respostas o rendimento, custo, estabilidade oxidativa e ponto de entupimento de filtro a frio (CFPP), e os limites foram estabelecidos de acordo com os dados experimentais e os parâmetros de conformidade estabelecidos pela legislação. A otimização multirresposta utilizando as equações preditivas, obtidas a partir do delineamento simplex-centroide acopladas às funções de desejabilidade, apresentou uma formulação ótima contendo 38,84% de óleo de soja, 21,90 % de sebo bovino e 39,25 % de gordura de ave com rendimento de 94,94 %, estabilidade oxidativa a 110 ºC de 8,99 horas, CFPP de 2,83 ºC e custo de US$ 864,60. A validação mostrou não haver diferença significativa entre os valores preditos e os valores experimentais. O delineamento de mistura e a otimização simplex-centroide se mostraram metodologias eficazes na obtenção de biodiesel B100, usando uma mistura de diferentes matérias-primas.</p>

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Chmielewski, Tomasz, Tomasz Kuczek, and Piotr Oramus. "Optimisation of electric arc model parameters based on simplex annealing and genetic algorithms." MATEC Web of Conferences 252 (2019): 05001. http://dx.doi.org/10.1051/matecconf/201925205001.

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This paper presents the method for obtaining the coefficients of the dynamic Cassie-Mayr electric arc model by means of annealing and genetic optimisation algorithms. The extraction of the coefficients can be obtained by means of the iterative fitting process based on e.g. multiple measurements results. However, this requires a significant effort and can generate significant costs. The approach presented in this paper relies solely on simulations. The methodology used herein consists in finding the match to the maximum produced TRV generated during high-voltage shunt reactor current breaking, for ideal switch and conductance based Cassie-Mayr circuit breaker models. This is done for a given chopping current value assigned to the ideal switch which is used as a target. The arc model coefficients are obtained by means of the optimisation process for various values of the desired chopping current level to be reflected by the Cassie-Mayr conductance-based electric arc model. As a result, an advanced conductance based model can be used for assessment of switching overvoltage. Genetic and simplex annealing algorithms have been selected for optimisation. The models as well as the optimisation process were conducted in EMTP-ATP software using its built-in functionalities. The article presents the error assessment and sample traces.

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Vivaldi, Valentina, Sara Sommariva, and Alberto Sorrentino. "A simplex method for the calibration of a MEG device." Communications in Applied and Industrial Mathematics 10, no. 2 (2019): 35–46. http://dx.doi.org/10.2478/caim-2019-0005.

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Abstract MagnetoEncephaloGraphy (MEG) devices are helmet–shaped arrays of sensors that measure the tiny magnetic fields produced by neural currents. As they operate at low temperature, they are typically immersed in liquid helium. However, during the cooling process the sensor position and shape can change, with respect to nominal values, due to thermal stress. This implies that an accurate sensor calibration is required before a MEG device is utilized in either neuroscientific research or clinical workflow. Here we describe a calibration scheme developed for the optimal use of a MEG system recently realized at the “Istituto di Cibernetica e Biofisica” of the Italian CNR. To achieve the calibration goal a dedicated magnetic source is used (calibration device) and the geometric parameters of the sensors are determined through an optimisation procedure, based on the Nelder-Mead algorithm, which maximises the correlation coefficient between the predicted and the recorded magnetic field. Then the sensitivity of the sensors is analytically estimated. The developed calibration procedure is validated with synthetic data mimicking a real scenario.

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Lampart, Piotr, Łukasz Witanowski, and Piotr Klonowicz. "Efficiency Optimisation of Blade Shape in Steam and ORC Turbines." Mechanics and Mechanical Engineering 22, no. 2 (2020): 553–64. http://dx.doi.org/10.2478/mme-2018-0044.

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AbstractThis paper is devoted to direct constrained optimisation of blading systems of large power and small power turbines so as to increase their internal efficiency. The optimisation is carried out using hybrid stochastic-deterministic methods such as a combination of a direct search method of Hooke-Jeeves and simulated annealing or a combination of a bat algorithm and simplex method of Nelder-Mead. Among free shape parameters are blade number and stagger angle, stacking blade line parameters and blade section (profile) parameters.One practical example of efficiency optimisation of turbine blading systems is modification of low load profiles PLK-R2 for high pressure (HP) stages of large power steam turbines. Another optimised geometry is that of an ORC radial-axial cogeneration turbine of 50 kWe. Up to 1% efficiency increase can easily be obtained from optimisation of HP blade profiles, especially by making the rotor blade more aft-loaded and reducing the intensity of endwall flows. Almost 2% efficiency rise was obtained for the optimised 50 kWe ORC turbine due to flow improvement at the suction side of the blade.

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Curt, C., I. Allais, N. Perrot, V. Leblanc, and G. Trystram. "Optimisation of the meat emulsification process using at-line human evaluations and the Simplex method." Journal of Food Engineering 64, no. 1 (2004): 33–41. http://dx.doi.org/10.1016/j.jfoodeng.2003.09.010.

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Niegodajew, Paweł, Maciej Marek, Witold Elsner, and Łukasz Kowalczyk. "Power Plant Optimisation—Effective Use of the Nelder-Mead Approach." Processes 8, no. 3 (2020): 357. http://dx.doi.org/10.3390/pr8030357.

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This paper demonstrates the use of a combined software package including IPSEpro and MATLAB in the optimisation of a modern thermal cycle. A 900 MW power plant unit (operating at ultra-supercritical conditions) was considered as the study object. The Nelder-Mead simplex-based, direct search method was used to increase power plant efficiency and to find the optimal thermal cycle configuration. As the literature reveals, the Nelder-Mead approach is very sensitive to the simplex size and to the choice of method coefficients, i.e., reflection, expansion and contraction. When these coefficients are improperly chosen, the finding of the optimal solution cannot be guaranteed, particularly in such complex systems as thermal cycles. Hence, the main goal of the present work was to demonstrate the capability of an integrated software package including IPSEpro, MATLAB and MS Excel in the optimisation process of a complex thermal cycle, as well as to examine the effectiveness of the most popular sets of Nelder-Mead coefficients previously proposed by other researchers. For the investigation purposes, the bleed and outlet pressures from the turbines were considered as decision variables, and the power plant efficiency was used as an objective function.

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Dissertations / Theses on the topic "Optimisation by simplex method"

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Luangpaiboon, Pongchanun. "A comparison of algorithms for automatic process optimisation." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324922.

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Guertler, Marion. "Modelling and solution methods for portfolio optimisation." Thesis, Brunel University, 2004. http://bura.brunel.ac.uk/handle/2438/4855.

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In this thesis modelling and solution methods for portfolio optimisation are presented. The investigations reported in this thesis extend the Markowitz mean-variance model to the domain of quadratic mixed integer programming (QMIP) models which are 'NP-hard' discrete optimisation problems. In addition to the modelling extensions a number of challenging aspects of solution algorithms are considered. The relative performances of sparse simplex (SSX) as well as the interior point method (IPM) are studied in detail. In particular, the roles of 'warmstart' and dual simplex are highlighted as applied to the construction of the efficient frontier which requires processing a family of problems; that is, the portfolio planning model stated in a parametric form. The method of solving QMIP models using the branch and bound algorithm is first developed; this is followed up by heuristics which improve the performance of the (discrete) solution algorithm. Some properties of the efficient frontier with discrete constraints are considered and a method of computing the discrete efficient frontier (DEF) efficiently is proposed. The computational investigation considers the efficiency and effectiveness in respect of the scale up properties of the proposed algorithm. The extensions of the real world models and the proposed solution algorithms make contribution as new knowledge.

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Hamilton, Daniel. "Decomposition and diet problems." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3798.

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The purpose of this thesis is to efficiently solve real life problems. We study LPs. We study an NLP and an MINLP based on what is known as the generalised pooling problem (GPP), and we study an MIP that we call the cattle mating problem. These problems are often very large or otherwise difficult to solve by direct methods, and are best solved by decomposition methods. During the thesis we introduce algorithms that exploit the structure of the problems to decompose them. We are able to solve row-linked, column-linked and general LPs efficiently by modifying the tableau simplex method, and suggest how this work could be applied to the revised simplex method. We modify an existing sequential linear programming solver that is currently used by Format International to solve GPPs, and show the modified solver takes less time and is at least as likely to find the global minimum as the old solver. We solve multifactory versions of the GPP by augmented Lagrangian decomposition, and show this is more efficient than solving the problems directly. We introduce a decomposition algorithm to solve a MINLP version of the GPP by decomposing it into NLP and ILP subproblems. This is able to solve large problems that could not be solved directly. We introduce an efficient decomposition algorithm to solve the MIP cattle mating problem, which has been adopted for use by the Irish Cattle Breeding Federation. Most of the solve methods we introduce are designed only to find local minima. However, for the multifactory version of the GPP we introduce two methods that give a good chance of finding the global minimum, both of which succeed in finding the global minimum on test problems.

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Wang, Yang. "Robust and stable discrete adjoint solver development for shape optimisation of incompressible flows with industrial applications." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24870.

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This thesis investigates stabilisation of the SIMPLE-family discretisations for incompressible flow and their discrete adjoint counterparts. The SIMPLE method is presented from typical \prediction-correction" point of view, but also using a pressure Schur complement approach, which leads to a wider class of schemes. A novel semicoupled implicit solver with velocity coupling is proposed to improve stability. Skewness correction methods are applied to enhance solver accuracy on non-orthogonal grids. An algebraic multi grid linear solver from the HYPRE library is linked to flow and discrete adjoint solvers to further stabilise the computation and improve the convergence rate. With the improved implementation, both of flow and discrete adjoint solvers can be applied to a wide range of 2D and 3D test cases. Results show that the semi-coupled implicit solver is more robust compared to the standard SIMPLE solver. A shape optimisation of a S-bend air flow duct from a VW Golf vehicle is studied using a CAD-based parametrisation for two Reynolds numbers. The optimised shapes and their flows are analysed to con rm the physical nature of the improvement. A first application of the new stabilised discrete adjoint method to a reverse osmosis (RO) membrane channel flow is presented. A CFD model of the RO membrane process with a membrane boundary condition is added. Two objective functions, pressure drop and permeate flux, are evaluated for various spacer geometries such as open channel, cavity, submerged and zigzag spacer arrangements. The flow and the surface sensitivity of these two objective functions is computed and analysed for these geometries. An optimisation with a node-base parametrisation approach is carried out for the zigzag con guration channel flow in order to reduce the pressure drop. Results indicate that the pressure loss can be reduced by 24% with a slight reduction in permeate flux by 0.43%.

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Koulibaly, Issa. "Automatisation et optimisation de la synthèse du ((pyridyl-4)-2 ethyl)-3 indole, précurseur d'un antidépresseur." Paris 6, 1986. http://www.theses.fr/1986PA066413.

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Dans le cadre des recherches concernant l'application des techniques d'automatisation et des méthodes d'optimisation, sur les procédés de fabrications industrielles de produits pharmaceutiques, nous avons choisi l'automatisation et l'optimisation de la synthèse d'un précurseur de l'indalpine, qui est un produit pharmaceutique important par ses propriétés d'antidépresseur. Nous montrons, dans la première partie de ce travail, qu'il est possible d'automatiser, à l'échelle du laboratoire, et pour un cout réduit, une synthèse organique complexe à l'aide d'un automate de bas de gamme et de capteurs et actionneurs adéquats, que l'automatisation nécessite une bonne description du mode opératoire; pour cela, nous avons utilisé le langage grafcet afin de structurer le mode opératoire industriel. Dans la deuxième partie, nous prouvons qu'il est aussi possible d'améliorer le rendement d'une synthèse organique en établissant la fonction réponse et en l'optimisant pour obtenir les coordonnées de l'optimum. Pour la synthèse concernée dans ce travail, le gain de rendement a été de 22 points.

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Ao, Wai Kei. "Electromagnetic damping for control of vibration in civil structures." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/31145.

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This thesis investigates an alternative solution to deal with the civil structure vibration. Non-contact electromagnetic or Eddy current damping is selected as a score of vibration suppression. Electromagnetic damping relies on the interaction between a permanent magnet and conductor. An electromagnetic damper (EMD) is applied both to a laboratory footbridge structure and 6-storey model-scale aluminium moment resisting frame (AMRF). In this first study the EMD is connected in series with an electronic shunt circuit to construct an electromagnetic shunt damper (EMSD). A robust optimisation method is applied to develop the corresponding optimal design formula of the EMSD. The principle of an EMSD is to convert mechanical energy to electrical energy. Hence, the induced electromotive force (emf) is generated by electromagnetic induction. This emf induces an amount of shunt damping, which is fedback to the structure to achieve vibration suppression. It was found that when the impedance was applied, the shunt damping feature was of a similar nature to viscous dampers. In contrast, when an RLC (resistance-inductance-capacitance) circuit is connected, the shunt damping is analogous to a tuned mass damper. A second form of EMD is Eddy current damper (ECD), which relies on a geometrical arrangement of permanent magnets and conductors to produce damping forces. The vertical and horizontal orientation of the magnet, unidirectional and alternative pole projection and moving different direction of the conductor are investigated. A theoretical study involving the infinite boundary and finite boundary (the method of images current) is carried out to obtain an analytical calculation of the damping force. On the basis of this analysis, one type of ECD prototype was physically built. A performance test was carried out to determine the damping characteristics of the ECD, which agreed with the results of the numerical analysis. In addition, the ECD was applied to control the dynamics of the 6-storey AMRF. It was found that, the ECD can effectively increase system damping and have a satisfactory control effect.

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AIDO, LAETITIA. "Optimisation de la fabrication de l'indole-2 carboxylate d'ethyle : automatisation de la reaction de wislicenus et thoma et de la reaction d'hydrogenation de brehm, etude de differents systemes de commande : correlateur logique (...) microprocesseur." Paris 6, 1986. http://www.theses.fr/1986PA066370.

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Cette etude a ete faite pour demontrer l'efficacite des methodes d'optimisation et d'automatisation; elle a permis un gain de rendement de 36 points (de 41 a 77%) associe a une forte diminution de la duree globale de la reaction (76h a 2h30)

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Huangfu, Qi. "High performance simplex solver." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7952.

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The dual simplex method is frequently the most efficient technique for solving linear programming (LP) problems. This thesis describes an efficient implementation of the sequential dual simplex method and the design and development of two parallel dual simplex solvers. In serial, many advanced techniques for the (dual) simplex method are implemented, including sparse LU factorization, hyper-sparse linear system solution technique, efficient approaches to updating LU factors and sophisticated dual simplex pivoting rules. These techniques, some of which are novel, lead to serial performance which is comparable with the best public domain dual simplex solver, providing a solid foundation for the simplex parallelization. During the implementation of the sequential dual simplex solver, the study of classic LU factor update techniques leads to the development of three novel update variants. One of them is comparable to the most efficient established approach but is much simpler in terms of implementation, and the other two are specially useful for one of the parallel simplex solvers. In addition, the study of the dual simplex pivoting rules identifies and motivates further investigation of how hyper-sparsity maybe promoted. In parallel, two high performance simplex solvers are designed and developed. One approach, based on a less-known dual pivoting rule called suboptimization, exploits parallelism across multiple iterations (PAMI). The other, based on the regular dual pivoting rule, exploits purely single iteration parallelism (SIP). The performance of PAMI is comparable to a world-leading commercial simplex solver. SIP is frequently complementary to PAMI in achieving speedup when PAMI results in slowdown.

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Awad, Barre Mohamed 1955. "APPLICATION OF THE SIMPLEX METHOD TO SLOPE STABILITY ANALYSIS." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276340.

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Koberstein, Achim. "The dual simplex method, techniques for a fast and stable implementation." kostenfrei, 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978580478.

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Books on the topic "Optimisation by simplex method"

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Seidel, Mike. The simplex method for linear constrained optimisation. Oxford Brookes University, 2002.

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Borgwardt, Karl Heinz. The Simplex Method. Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-61578-8.

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Kidd, J. L. An implementation of the simplex method. UMIST, 1993.

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Maros, Istv n. Computational techniques of the simplex method. Kluwer Academic Publishers, 2003.

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Maros, István. Computational Techniques of the Simplex Method. Springer US, 2003.

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Computational techniques of the simplex method. Kluwer Academic Publishers, 2003.

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Maros, István. Computational Techniques of the Simplex Method. Springer US, 2003. http://dx.doi.org/10.1007/978-1-4615-0257-9.

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Borgwardt, Karl Heinz. The simplex method, a probabilistic analysis. Springer-Verlag, 1987.

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Moore, G. L. Optimization of an inductively coupled plasma by the simplex method. Council for Mineral Technology, 1985.

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Reeb, J. E. Using the simplex method to solve linear programming maximization problems. Oregon State University Extension Service, 1998.

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Book chapters on the topic "Optimisation by simplex method"

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Dowson, Nicholas, Paul Thomas, Jye Smith, Olivier Salvado, and Stephen Rose. "Large Scale Simplex Optimisation to Accelerate Kinetic Analysis." In Computational Methods for Molecular Imaging. Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18431-9_4.

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Bhunia, Asoke Kumar, Laxminarayan Sahoo, and Ali Akbar Shaikh. "Simplex Method." In Springer Optimization and Its Applications. Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-32-9967-2_3.

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PAN, Ping-Qi. "Simplex Method." In Linear Programming Computation. Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-40754-3_3.

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Vasilyev, F. P., and A. Yu Ivanitskiy. "Simplex Method." In In-Depth Analysis of Linear Programming. Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-015-9759-3_1.

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Stanimirović, Ivan. "Simplex Method." In Advances in Optimization and Linear Programming. Apple Academic Press, 2021. http://dx.doi.org/10.1201/9781003256052-2.

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Luenberger, David G., and Yinyu Ye. "The Simplex Method." In Linear and Nonlinear Programming. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-18842-3_3.

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Vanderbei, Robert J. "The Simplex Method." In International Series in Operations Research & Management Science. Springer US, 2008. http://dx.doi.org/10.1007/978-0-387-74388-2_2.

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Luenberger, David G., and Yinyu Ye. "The Simplex Method." In Linear and Nonlinear Programming. Springer US, 2008. http://dx.doi.org/10.1007/978-0-387-74503-9_3.

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Srinivasan, R. "The Simplex Method." In Strategic Business Decisions. Springer India, 2014. http://dx.doi.org/10.1007/978-81-322-1901-9_3.

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Bajalinov, Erik B. "The Simplex Method." In Linear-Fractional Programming Theory, Methods, Applications and Software. Springer US, 2003. http://dx.doi.org/10.1007/978-1-4419-9174-4_4.

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Conference papers on the topic "Optimisation by simplex method"

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Herbert, Luke T., and Robin Sharp. "Optimisation of BPMN Business Models via Model Checking." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-13047.

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We present a framework for the optimisation of business processes modelled in the business process modelling language BPMN, which builds upon earlier work, where we developed a model checking based method for the analysis of BPMN models. We define a structure for expressing optimisation goals for synthesized BPMN components, based on probabilistic computation tree logic and real-valued reward structures of the BPMN model, allowing for the specification of complex quantitative goals. We here present a simple algorithm, inspired by concepts from evolutionary algorithms, which iteratively generates candidate improved processes based on the fittest of the previous generation. The evaluation of the fitness of each candidate in a generation is performed via model checking, detailed in previous work. At each iteration, this allows the determination of the precise numerical evaluation of the performance of a candidate in terms of the specified goals. A discussion of this method’s application, and the degree of optimization which is possible, is illustrated using an example drawn from the healthcare industry.

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Sanliturk, Kenan Y., David J. Ewins, Robert Elliott, and Jeff S. Green. "Friction Damper Optimisation: Simulation of Rainbow Tests." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-336.

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Friction dampers have been used to reduce turbine blade vibration levels for a considerable period of time. However, optimal design of these dampers has been quite difficult due both to a lack of adequate theoretical predictions and to difficulties in conducting reliable experiments. One of the difficulties of damper weight optimisation via the experimental route has been the inevitable effects of mistuning. Also, conducting separate experiments for different damper weights involves excessive cost. Therefore, current practice in the turbomachinery industry has been to conduct so-called ‘rainbow tests’ where friction dampers with different weights are placed between blades with a predefined configuration. However, it has been observed that some rainbow test results have been difficult to interpret and have been inconclusive for determining the optimum damper weight for a given bladed-disc assembly. A new method of analysis — a combination of Harmonic Balance Method and structural modification approaches — is presented in this paper for the analysis of structures with friction interfaces and the method is applied to search for qualitative answers about the so-called ‘rainbow tests’ in turbomachinery applications. A simple lumped-parameter model of a bladed-disc model was used and different damper weights were modelled using friction elements with different characteristics. Resonance response levels were obtained for bladed discs with various numbers of blades under various engine-order excitations. It was found that rainbow tests, where friction dampers with different weights are used on the same bladed-disc assembly, can be used to find the optimum damper weight if the mode of vibration concerned has weak blade-to-blade coupling (the case where the disc is almost rigid and blades vibrate almost independently from each other). Otherwise, it is very difficult to draw any reliable conclusion from such expensive experiments.

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Holgate, Philip, and Alexander Rasa. "Optimisation of a viscoelastic damping material using dynamic mechanical analysis." In SNAME 5th World Maritime Technology Conference. SNAME, 2015. http://dx.doi.org/10.5957/wmtc-2015-039.

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Reducing vibration in marine craft can return a wide range of benefits from a reduction in noise output, resulting in increased passenger and crew comfort, to increasing component life. Damping is one method of reducing structural vibration, by which mechanical vibrational energy is dissipated into heat through a viscoelastic material. In order for these materials to be effective, their properties must be well understood. Dynamic mechanical analysis (DMA) is one method to determine parameters relating to material behaviour under flexural stress. In this paper it is used to optimise a viscoelastic damping material to fit specific requirements. The product requirements were defined by a specific structural vibration problem with a low temperature operational range of -5 °C to 5 °C (23 °F to 41 °F). Previously, a viscoelastic damping material had been developed for a rail application, with operating temperatures around -20 °C (-4 °F), along with another optimised for standard ambient temperatures. A variety of simple chemical formulations were prepared adjusting the blend ratio of the two different polymers used in these established products. Samples were tested and analysed through the DMA method to determine the optimum damping performance over the required temperature range before the product was applied in a marine application. The optimum blend of the harder and softer polymer at these temperatures was 75:25, resulting in a viscoelastic damping material that is effective at the designated temperature for 16, 25 and 50 Hz. Loss factor peaked at a tan δ of 0.69 at 0 °C for the proposed product compared with 0.55 and 0.66 for the -20 °C (-4 °F) and standard ambient temperature variants respectively. The usefulness of DMA for research and development of products with specific requirements is discussed with reference to this method applied in this project.

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Duclos, Gaelle, Aurelien Babarit, and Alain H. Clement. "Power Take Off Damping Optimisation With Regard to Wave Climate." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51256.

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Considered as a source of renewable energy, wave is a resource which exhibit high variability at all time scales. Furthermore wave climate also changes significatively from place to place. Wave energy converters are very often tuned to suit the more frequent significant wave period of the project site. In this paper we show that optimizing the device necessitates to account for all possible wave conditions weighted by their occurrence frequency, as generally given by the classical wave climate scatter diagrams. Instead of a real device, a generic and very simple wave energy converter was considered here. We show how the optimal parameters can be different considering whether all wave conditions are accounted for or not, whether the device is controlled or not, whether the vertical motion is limited or not. We also show how they depend on the area where the device is to be deployed, by applying the same method to three very different sites.

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Coppinger, Miles, Graham Cox, John Hannis, and Nigel Cox. "Cycle Optimisation Using an Advanced, Real Engine Performance Prediction Model." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30515.

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A whole gas-turbine engine model has been developed incorporating all of the key turbomachinery aerothermal relationships. The aim of the model has been to predict trends in gas-turbine performance with a high degree of confidence that they reflect real engine design limitations. Simple cycles, recuperated, inter-cooled, and inter-cooled recuperated cycles can be assessed across a wide of range of operating parameters. The model is spreadsheet-based with additional macro programming. The major part of it is concerned with establishing representative overall turbine characteristics. A non-integer number of stages is determined as a function of technology level inputs. Individual stage geometry features are derived allowing the calculation of the coolant requirements and efficiencies. The results of various studies are presented for a number of cycle types. The resulting trends are believed to be sensible because of the realistic turbine features. Confidence in the method is established by the modelling of a number of existing industrial gas turbines.

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Pitman, Mark W., and Anthony D. Lucey. "Optimal Swimming Modes of a Homo-Sapien Performing Butterfly-Stroke Kick." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93938.

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This paper outlines the development and application of a computational method that finds the most efficient two-dimensional swimming mode of a human performing fully submerged butterfly-stroke kick at high Reynolds number. The optimal solution of this non-linear problem is found using a Genetic Algorithm (GA) search method where possible solutions compete in a ‘survival of the fittest’ scheme to ‘breed’ the optimal solution. The swimming is modelled using Discrete Vortex Method (DVM) and Boundary Element Method (BEM) computational techniques. The BEM solves for the inviscid flow field around the two-dimensional body while the shedding of vorticies from joints where the curvature is high (ie. knee, waist and ankle joints) generate the vortex structures necessary for propulsion. The motion of the limbs is characterised by a displacement function which includes the possibility for simple harmonic or non-harmonic motion with a ‘rest’ period in the kick. The finite number of joints means that a finite length parameter set can be developed which characterises the motion of the swimming body. This parameter set is fed into the GA to perform the optimisation based on a scoring function. In this case, the scoring function is simply the distance that the body swims in a set amount of time. The objective of the GA is to maximise this score for a set kicking frequency. This method opens a wider possibility for optimisation of a variety of systems that involve fluid-structure interactions, particulary the possibility of optimisation in the non-linear regime of prescribed motion coupled with compliant surfaces (such as rubbery flippers) that could further increase efficiency.

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Gobbi, Massimiliano. "Optimal and Robust Design of Ground Vehicle Systems." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95471.

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A new approach for the design of vehicle subsystems is addressed in the paper. The new approach is based not only on the theory of multi-objective optimisation but also on robust design. The method is characterised both by the optimisation of the objective functions (corresponding to system performance indices) and by the reduction (or minimisation) of the sensitivity (variance) of the performance indices to stochastic perturbations. Such variances are computed (very quickly) by means of an original procedure based on the global approximation of the objective functions. Additionally, with respect to the mentioned features, the new approach is based on both a special study to explore all of the feasible design solutions, and on a global sensitivity procedure to analyse (in a stochastic context) the influence of each design variable on each objective function. Pareto-optimal design solutions for different levels of “robustness” can be computed in a very short time. The optimisation method has been tested on a relatively simple problem and applied with successful results to a complex design problem related to vehicle design.

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Schabowski, Zbigniew, Howard Hodson, Davide Giacche, Bronwyn Power, and Mark R. Stokes. "Aeromechanical Optimisation of a Winglet-Squealer Tip for an Axial Turbine." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23542.

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The possibility of reducing the over tip leakage loss of unshrouded axial turbine rotors has been investigated in an experiment using a linear cascade of turbine blades and by using CFD. A numerical optimisation of a winglet-squealer geometry was performed. The optimisation involved the structural analysis alongside the CFD. Significant effects of the tip design on the tip gap flow pattern, loss generation and mechanical deformation under centrifugal loads were found. The results of the optimisation process were verified by low speed cascade testing. The measurements showed that the optimised winglet-squealer design had a lower loss than the flat tip at all of the tested tip gaps. At the same time, it offered a 37% reduction in the rate of change of the aerodynamic loss with the tip gap size. The optimised tip geometry was used to experimentally assess the effects of the opening of the tip cavity in the leading edge part of the blade and the inclination of the pressure side squealer from the radial direction. The opening of the cavity had a negligible effect on the aerodynamic performance of the cascade. The squealer lean resulted in a small reduction of the aerodynamic loss at all the tested tip gaps. It was shown that a careful consideration of the mechanical aspects of the winglet is required during the design process. Mechanically unconstrained designs could result in unacceptable deformation of the winglet due to centrifugal loads. An example winglet geometry is presented that produced a similar aerodynamic loss to that of the optimised tip but had a much worse mechanical performance. The mechanisms leading to the reduction of the tip leakage loss were identified. Using this knowledge, a simple method for designing the tip geometry of a shroudless turbine rotor is proposed. Numerical calculations indicated that the optimised low-speed winglet-squealer geometry maintained its aerodynamic superiority over the flat tip blade with the exit Mach number increased from 0.1 to 0.8.

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Dennis, R. J., N. A. Leggatt, and E. A. Kutarski. "Investigation of the Performance of the Contour Residual Stress Measurement Method When Applied to Welded Pipe Structures." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77470.

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The ‘Contour Method’ is a relatively new relaxation method for residual stress measurement and may be seen as an evolution of established methods such as hole drilling. The general procedure when applying the Contour Method is cutting, measurement and calculation of residual stress normal to the cut plane using Bueckner’s principle of elastic superposition. That is the residual stresses are determined from the measured profile of a cut surface. While the Contour Method is simple in concept there are certain underlying issues relating to the cutting process that may lead to uncertainties in the measured results. Principally the issues are that of constraint and plasticity during the cutting process and the influence that they have on the measured residual stresses. Both of these aspects have been investigated in previous work by simulating the entire contour measurement method process using finite element techniques for ‘simple’ flat plate welded specimens. Here that work is further investigated and extended by application to a 316 Stainless Steel welded pipe structure containing a part-circumferential repair. This more complex structure and residual stress field is of significantly greater engineering interest. The key objective of this work is to ascertain the feasibility of and further our understanding of the performance of the Contour Method. Furthermore this work has the potential to provide a method to support the optimisation of the contour measurement process when applied to more complex engineering components.

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Day, Sandy. "The Design of Yacht Sailplans for Maximal Upwind Speed." In SNAME 12th Chesapeake Sailing Yacht Symposium. SNAME, 1995. http://dx.doi.org/10.5957/csys-1995-001.

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A great deal of research, both computational and experiment based, has been carried out on the optimisation of hull geometry for minimal hydrodynamic resistance; however, rather less effort has been expended on the equivalent problem of optimising the sailplan geometry. The goals of the optimisation procedures which have been adopted for sail optimisation are somewhat diverse; some researchers have concentrated on the maximisation of aerodynamic drive force, with or without constraints on heeling moment, whilst other approaches have included simple representations of hydrodynamic sideforce and induced drag. Much of the work has concentrated on optimisation of the distribution of aerodynamic lift over the sailplan without specifying how the lift distribution may be achieved in practice if indeed the lift distribution can be obtained within the practical constraints of conventional rig technology. It is argued here that, from the point of view of yacht design, an appropriate goal for the optimisation is the selection of the sailplan geometry which yields the best performance for a given hull form over a suitably weighted range of windspeeds. In this work, the aspect of performance considered as being of primary importance is upwind speed. A method is presented by which the principal dimensions of the rig - luff length, foot length etc. - may be chosen so as to maximise upwind or close reaching speed for a particular yacht in a given wind strength. The aerodynamic performance of the rig is predicted using a non-linear vortex lattice model; viscous effects, including the effect of the mast, are included using an ad hoc approach based on two dimensional experiment data. The hydrodynamics and hydrostatics of the hull are obtained using a performance prediction approach based on the well known Delft yacht hull series. Optimisation of the rig geometry is carried out using a stochastic technique known as a structured genetic algorithm. Results are presented for two variations on the sloop rig; the first employs a mainsail with an essentially triangular planform, whilst the second allows the inclusion of a substantial roach, leading to sails of the form normally associated with full length battens. The hull forms considered include typical examples of both modem and slightly older racing yachts. The sensitivity of the geometries obtained to constraints unrelated to upwind speed - such as structural integrity or offwind sail carrying capability - is also illustrated.

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Reports on the topic "Optimisation by simplex method"

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Ayoul-Guilmard, Q., S. Ganesh, F. Nobile, R. Rossi, and C. Soriano. D6.3 Report on stochastic optimisation for simple problems. Scipedia, 2021. http://dx.doi.org/10.23967/exaqute.2021.2.001.

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This report addresses the general matter of optimisation under uncertainties, following a previous report on stochastic sensitivities (deliverable 6.2). It describes several theoretical methods, as well their application into implementable algorithms. The specific case of the conditional value at risk chosen as risk measure, with its challenges, is prominently discussed. In particular, the issue of smoothness – or lack thereof – is addressed through several possible approaches. The whole report is written in the context of high-performance computing, with concern for parallelisation and cost-efficiency.

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Bixby, Robert E. Implementing the Simplex Method: The Initial Basis. Defense Technical Information Center, 1991. http://dx.doi.org/10.21236/ada453079.

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Thompson, Gerald L. An Integral Simplex Method for Solving Combinatorial Optimization Problems. Defense Technical Information Center, 1996. http://dx.doi.org/10.21236/ada352010.

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Ye, Yinyu. Eliminating columns in the simplex method for linear programming. Office of Scientific and Technical Information (OSTI), 1987. http://dx.doi.org/10.2172/5761063.

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Gill, Philip E., Walter Murray, and Michael A. Saunders. Interior-Point Methods for Linear Programming: A Challenge to the Simplex Method. Defense Technical Information Center, 1988. http://dx.doi.org/10.21236/ada198944.

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Nobile, F., Q. Ayoul-Guilmard, S. Ganesh, et al. D6.5 Report on stochastic optimisation for wind engineering. Scipedia, 2022. http://dx.doi.org/10.23967/exaqute.2022.3.04.

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This report presents the latest methods of optimisation under uncertainties investigated in the ExaQUte project, and their applications to problems related to civil and wind engineering. The measure of risk throughout the report is the conditional value at risk. First, the reference method is presented: the derivation of sensitivities of the risk measure; their accurate computation; and lastly, a practical optimisation algorithm with adaptive statistical estimation. Second, this method is directly applied to a nonlinear relaxation oscillator (FitzHugh–Nagumo model) with numerical experiments to demonstrate its performance. Third, the optimisation method is adapted to the shape optimisation of an airfoil and illustrated by a large-scale experiment on a computing cluster. Finally, the benchmark of the shape optimisation of a tall building under a turbulent flow is presented, followed by an adaptation of the optimisation method. All numerical experiments showcase the open-source software stack of the ExaQUte project for large-scale computing in a distributed environment.

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Ayoul-Guilmard, Q., F. Nobile, S. Ganesh, et al. D6.4 Report on stochastic optimisation for unsteady problems. Scipedia, 2021. http://dx.doi.org/10.23967/exaqute.2021.2.003.

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This report brings together methodological research on stochastic optimisation and work on benchmark and target applications of the ExaQute project, with a focus on unsteady problems. A practical, general method for the optimisation of the conditional value at risk is proposed. Three different optimisation problems are described: an oscillator problem selected as a suitable trial and illustration case; the shape optimisation of an airfoil, chosen as a benchmark application in the project; the shape optimisation of a tall building, which is the challenging target application set for ExaQUte. For each problem, the current developments and results are presented, the application of the proposed method is discussed, and the work to be done until the end of the project is laid out.

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Lee, Yubin. The Optimization of Machining Parameters for Milling Operations by Using the Nelder Mead Simplex Method. Portland State University Library, 2000. http://dx.doi.org/10.15760/etd.7271.

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