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Shinji Nishiwaki - One of the best experts on this subject based on the ideXlab platform.
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matlab code for a level set based topology Optimization Method using a reaction diffusion equation
Structural and Multidisciplinary Optimization, 2015Co-Authors: Masaki Otomori, Kazuhiro Izui, Takayuki Yamada, Shinji NishiwakiAbstract:This paper presents a simple Matlab implementation for a level set-based topology Optimization Method in which the level set function is updated using a reaction diffusion equation, which is different from conventional level set-based approaches (Allaire et al. 2002, 2004; Wang et al. 2003) that use the Hamilton-Jacobi equation to update the level set function. With this Method, the geometrical complexity of optimized configurations can be easily controlled by appropriately setting a regularization parameter. We explain the code in detail, and also the derivation of the topological derivative that is used in the level set-based topology Optimization. Numerical results for stiffness maximization problems are provided to facilitate the reader's understanding. The presented code is intended for educational purposes only. This paper was inspired by previously published papers presenting Matlab code for a SIMP Method (Sigmund 2001; Andreassen et al. 2011), a level set-based Method (Challis 2010), and FreeFem ++ code for a structural Optimization Method (Allaire and Pantz 2006). Readers can investigate results provided by these different Methods and discover the prominent aspects of each particular Method. The code presented here can be downloaded from http://www.osdel.me.kyoto-u.ac.jp/members/yamada/codes.html.
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a topology Optimization Method for a coupled thermal fluid problem using level set boundary expressions
International Journal of Heat and Mass Transfer, 2015Co-Authors: Kentaro Yaji, Kazuhiro Izui, Takayuki Yamada, Seiji Kubo, Shinji NishiwakiAbstract:Abstract This paper presents a topology Optimization Method for a coupled thermal–fluid problem based on the two- and three-dimensional steady-state Navier–Stokes and energy equations. In this research, the Optimization problem is formulated as a heat exchange maximization problem to obtain structures that function as high-performance cooling devices. Such devices, for example, liquid-cooled heat sinks, have recently attracted considerable attention as an engineering application for thermal cooling devices. The proposed Optimization Method employs level set boundary expressions and a Tikhonov-based regularization scheme enables qualitative control of the geometric complexity of the optimal configurations. Using the developed Methodology, we provide two- and three-dimensional numerical examples that confirm the applicability, from an engineering standpoint, of the Optimization Method for the design of cooling devices.
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a topology Optimization Method based on the level set Method for the design of negative permeability dielectric metamaterials
Computer Methods in Applied Mechanics and Engineering, 2012Co-Authors: Masaki Otomori, Kazuhiro Izui, Shinji Nishiwaki, Takayuki Yamada, Jacob AndkjaerAbstract:Abstract This paper presents a level set-based topology Optimization Method for the design of negative permeability dielectric metamaterials. Metamaterials are artificial materials that display extraordinary physical properties that are unavailable with natural materials. The aim of the formulated Optimization problem is to find optimized layouts of a dielectric material that achieve negative permeability. The presence of grayscale areas in the optimized configurations critically affects the performance of metamaterials, positively as well as negatively, but configurations that contain grayscale areas are highly impractical from an engineering and manufacturing point of view. Therefore, a topology Optimization Method that can obtain clear optimized configurations is desirable. Here, a level set-based topology Optimization Method incorporating a fictitious interface energy is applied to a negative permeability dielectric metamaterial design problem. The Optimization algorithm uses the Finite Element Method (FEM) for solving the equilibrium and adjoint equations, and design problems are formulated for both two- and three-dimensional cases. First, the level set-based topology Optimization Method is explained, and the Optimization problems for the design of metamaterials are then discussed. Several optimum design examples for the design of dielectric metamaterials that demonstrate negative effective permeability at prescribed frequencies are provided to confirm the utility and validity of the presented Method.
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a level set based topology Optimization Method for maximizing thermal diffusivity in problems including design dependent effects
Journal of Mechanical Design, 2011Co-Authors: Takayuki Yamada, Kazuhiro Izui, Shinji NishiwakiAbstract:This paper proposes an optimum design Method, based on our level set-based topology Optimization Method, for maximizing thermal diffusivity in problems dealing with generic heat transfer boundaries that include design-dependent boundary conditions. First, a topology Optimization Method using a level set model incorporating a fictitious interface energy for regularizing the topology Optimization is briefly discussed. Next, an Optimization Method for maximizing thermal diffusivity is formulated based on the concept of total potential energy. An Optimization algorithm that uses the finite element Method when solving the equilibrium equation and updating the level set function is then constructed. Finally, several numerical examples are provided to confirm the utility and validity of the proposed topology Optimization Method.
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a structural Optimization Method incorporating level set boundary expressions based on the concept of the phase field Method
Journal of Environment and Engineering, 2011Co-Authors: Takayuki Yamada, Kazuhiro Izui, Shinji Nishiwaki, Masataka Yoshimura, Akihiro TakezawaAbstract:Topology Optimization has been successfully used in many industries, especially those engaged in the design and manufacturing of mechanical devices, but numerical problems are often encountered, such as grayscale representations of obtained composites. A type of structural Optimization Method using the level set theory for boundary expressions has been proposed, in which the outlines of target structures are implicitly represented using the level set function, and optimal configurations are obtained by updating this function based on the shape sensitivities. Level set-based Methods typically have a drawback, however, in that topological changes that increase the number of holes in the material domain are not allowed. To overcome the above numerical and topological problems, this paper proposes a new topology Optimization Method incorporating level set boundary expressions based on the concept of the phase field Method, which we apply to a minimum mean compliance problem. First, a structural Optimization problem is formulated based on a boundary expression, using the level set function. Next, a time evolutionary equation for updating the level set function is formulated based on the concept of the phase field Method, and the minimum mean compliance problem is formulated using a level set boundary expression. An Optimization algorithm for the topology Optimization incorporating the level set boundary expression based on the concept of the phase field Method is then derived. Several examples are provided to confirm the usefulness of the proposed structural topology Optimization Method.
Takayuki Yamada - One of the best experts on this subject based on the ideXlab platform.
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matlab code for a level set based topology Optimization Method using a reaction diffusion equation
Structural and Multidisciplinary Optimization, 2015Co-Authors: Masaki Otomori, Kazuhiro Izui, Takayuki Yamada, Shinji NishiwakiAbstract:This paper presents a simple Matlab implementation for a level set-based topology Optimization Method in which the level set function is updated using a reaction diffusion equation, which is different from conventional level set-based approaches (Allaire et al. 2002, 2004; Wang et al. 2003) that use the Hamilton-Jacobi equation to update the level set function. With this Method, the geometrical complexity of optimized configurations can be easily controlled by appropriately setting a regularization parameter. We explain the code in detail, and also the derivation of the topological derivative that is used in the level set-based topology Optimization. Numerical results for stiffness maximization problems are provided to facilitate the reader's understanding. The presented code is intended for educational purposes only. This paper was inspired by previously published papers presenting Matlab code for a SIMP Method (Sigmund 2001; Andreassen et al. 2011), a level set-based Method (Challis 2010), and FreeFem ++ code for a structural Optimization Method (Allaire and Pantz 2006). Readers can investigate results provided by these different Methods and discover the prominent aspects of each particular Method. The code presented here can be downloaded from http://www.osdel.me.kyoto-u.ac.jp/members/yamada/codes.html.
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a topology Optimization Method for a coupled thermal fluid problem using level set boundary expressions
International Journal of Heat and Mass Transfer, 2015Co-Authors: Kentaro Yaji, Kazuhiro Izui, Takayuki Yamada, Seiji Kubo, Shinji NishiwakiAbstract:Abstract This paper presents a topology Optimization Method for a coupled thermal–fluid problem based on the two- and three-dimensional steady-state Navier–Stokes and energy equations. In this research, the Optimization problem is formulated as a heat exchange maximization problem to obtain structures that function as high-performance cooling devices. Such devices, for example, liquid-cooled heat sinks, have recently attracted considerable attention as an engineering application for thermal cooling devices. The proposed Optimization Method employs level set boundary expressions and a Tikhonov-based regularization scheme enables qualitative control of the geometric complexity of the optimal configurations. Using the developed Methodology, we provide two- and three-dimensional numerical examples that confirm the applicability, from an engineering standpoint, of the Optimization Method for the design of cooling devices.
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a topology Optimization Method based on the level set Method for the design of negative permeability dielectric metamaterials
Computer Methods in Applied Mechanics and Engineering, 2012Co-Authors: Masaki Otomori, Kazuhiro Izui, Shinji Nishiwaki, Takayuki Yamada, Jacob AndkjaerAbstract:Abstract This paper presents a level set-based topology Optimization Method for the design of negative permeability dielectric metamaterials. Metamaterials are artificial materials that display extraordinary physical properties that are unavailable with natural materials. The aim of the formulated Optimization problem is to find optimized layouts of a dielectric material that achieve negative permeability. The presence of grayscale areas in the optimized configurations critically affects the performance of metamaterials, positively as well as negatively, but configurations that contain grayscale areas are highly impractical from an engineering and manufacturing point of view. Therefore, a topology Optimization Method that can obtain clear optimized configurations is desirable. Here, a level set-based topology Optimization Method incorporating a fictitious interface energy is applied to a negative permeability dielectric metamaterial design problem. The Optimization algorithm uses the Finite Element Method (FEM) for solving the equilibrium and adjoint equations, and design problems are formulated for both two- and three-dimensional cases. First, the level set-based topology Optimization Method is explained, and the Optimization problems for the design of metamaterials are then discussed. Several optimum design examples for the design of dielectric metamaterials that demonstrate negative effective permeability at prescribed frequencies are provided to confirm the utility and validity of the presented Method.
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a level set based topology Optimization Method for maximizing thermal diffusivity in problems including design dependent effects
Journal of Mechanical Design, 2011Co-Authors: Takayuki Yamada, Kazuhiro Izui, Shinji NishiwakiAbstract:This paper proposes an optimum design Method, based on our level set-based topology Optimization Method, for maximizing thermal diffusivity in problems dealing with generic heat transfer boundaries that include design-dependent boundary conditions. First, a topology Optimization Method using a level set model incorporating a fictitious interface energy for regularizing the topology Optimization is briefly discussed. Next, an Optimization Method for maximizing thermal diffusivity is formulated based on the concept of total potential energy. An Optimization algorithm that uses the finite element Method when solving the equilibrium equation and updating the level set function is then constructed. Finally, several numerical examples are provided to confirm the utility and validity of the proposed topology Optimization Method.
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a structural Optimization Method incorporating level set boundary expressions based on the concept of the phase field Method
Journal of Environment and Engineering, 2011Co-Authors: Takayuki Yamada, Kazuhiro Izui, Shinji Nishiwaki, Masataka Yoshimura, Akihiro TakezawaAbstract:Topology Optimization has been successfully used in many industries, especially those engaged in the design and manufacturing of mechanical devices, but numerical problems are often encountered, such as grayscale representations of obtained composites. A type of structural Optimization Method using the level set theory for boundary expressions has been proposed, in which the outlines of target structures are implicitly represented using the level set function, and optimal configurations are obtained by updating this function based on the shape sensitivities. Level set-based Methods typically have a drawback, however, in that topological changes that increase the number of holes in the material domain are not allowed. To overcome the above numerical and topological problems, this paper proposes a new topology Optimization Method incorporating level set boundary expressions based on the concept of the phase field Method, which we apply to a minimum mean compliance problem. First, a structural Optimization problem is formulated based on a boundary expression, using the level set function. Next, a time evolutionary equation for updating the level set function is formulated based on the concept of the phase field Method, and the minimum mean compliance problem is formulated using a level set boundary expression. An Optimization algorithm for the topology Optimization incorporating the level set boundary expression based on the concept of the phase field Method is then derived. Several examples are provided to confirm the usefulness of the proposed structural topology Optimization Method.
Kazuhiro Izui - One of the best experts on this subject based on the ideXlab platform.
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matlab code for a level set based topology Optimization Method using a reaction diffusion equation
Structural and Multidisciplinary Optimization, 2015Co-Authors: Masaki Otomori, Kazuhiro Izui, Takayuki Yamada, Shinji NishiwakiAbstract:This paper presents a simple Matlab implementation for a level set-based topology Optimization Method in which the level set function is updated using a reaction diffusion equation, which is different from conventional level set-based approaches (Allaire et al. 2002, 2004; Wang et al. 2003) that use the Hamilton-Jacobi equation to update the level set function. With this Method, the geometrical complexity of optimized configurations can be easily controlled by appropriately setting a regularization parameter. We explain the code in detail, and also the derivation of the topological derivative that is used in the level set-based topology Optimization. Numerical results for stiffness maximization problems are provided to facilitate the reader's understanding. The presented code is intended for educational purposes only. This paper was inspired by previously published papers presenting Matlab code for a SIMP Method (Sigmund 2001; Andreassen et al. 2011), a level set-based Method (Challis 2010), and FreeFem ++ code for a structural Optimization Method (Allaire and Pantz 2006). Readers can investigate results provided by these different Methods and discover the prominent aspects of each particular Method. The code presented here can be downloaded from http://www.osdel.me.kyoto-u.ac.jp/members/yamada/codes.html.
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a topology Optimization Method for a coupled thermal fluid problem using level set boundary expressions
International Journal of Heat and Mass Transfer, 2015Co-Authors: Kentaro Yaji, Kazuhiro Izui, Takayuki Yamada, Seiji Kubo, Shinji NishiwakiAbstract:Abstract This paper presents a topology Optimization Method for a coupled thermal–fluid problem based on the two- and three-dimensional steady-state Navier–Stokes and energy equations. In this research, the Optimization problem is formulated as a heat exchange maximization problem to obtain structures that function as high-performance cooling devices. Such devices, for example, liquid-cooled heat sinks, have recently attracted considerable attention as an engineering application for thermal cooling devices. The proposed Optimization Method employs level set boundary expressions and a Tikhonov-based regularization scheme enables qualitative control of the geometric complexity of the optimal configurations. Using the developed Methodology, we provide two- and three-dimensional numerical examples that confirm the applicability, from an engineering standpoint, of the Optimization Method for the design of cooling devices.
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a topology Optimization Method based on the level set Method for the design of negative permeability dielectric metamaterials
Computer Methods in Applied Mechanics and Engineering, 2012Co-Authors: Masaki Otomori, Kazuhiro Izui, Shinji Nishiwaki, Takayuki Yamada, Jacob AndkjaerAbstract:Abstract This paper presents a level set-based topology Optimization Method for the design of negative permeability dielectric metamaterials. Metamaterials are artificial materials that display extraordinary physical properties that are unavailable with natural materials. The aim of the formulated Optimization problem is to find optimized layouts of a dielectric material that achieve negative permeability. The presence of grayscale areas in the optimized configurations critically affects the performance of metamaterials, positively as well as negatively, but configurations that contain grayscale areas are highly impractical from an engineering and manufacturing point of view. Therefore, a topology Optimization Method that can obtain clear optimized configurations is desirable. Here, a level set-based topology Optimization Method incorporating a fictitious interface energy is applied to a negative permeability dielectric metamaterial design problem. The Optimization algorithm uses the Finite Element Method (FEM) for solving the equilibrium and adjoint equations, and design problems are formulated for both two- and three-dimensional cases. First, the level set-based topology Optimization Method is explained, and the Optimization problems for the design of metamaterials are then discussed. Several optimum design examples for the design of dielectric metamaterials that demonstrate negative effective permeability at prescribed frequencies are provided to confirm the utility and validity of the presented Method.
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a level set based topology Optimization Method for maximizing thermal diffusivity in problems including design dependent effects
Journal of Mechanical Design, 2011Co-Authors: Takayuki Yamada, Kazuhiro Izui, Shinji NishiwakiAbstract:This paper proposes an optimum design Method, based on our level set-based topology Optimization Method, for maximizing thermal diffusivity in problems dealing with generic heat transfer boundaries that include design-dependent boundary conditions. First, a topology Optimization Method using a level set model incorporating a fictitious interface energy for regularizing the topology Optimization is briefly discussed. Next, an Optimization Method for maximizing thermal diffusivity is formulated based on the concept of total potential energy. An Optimization algorithm that uses the finite element Method when solving the equilibrium equation and updating the level set function is then constructed. Finally, several numerical examples are provided to confirm the utility and validity of the proposed topology Optimization Method.
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a structural Optimization Method incorporating level set boundary expressions based on the concept of the phase field Method
Journal of Environment and Engineering, 2011Co-Authors: Takayuki Yamada, Kazuhiro Izui, Shinji Nishiwaki, Masataka Yoshimura, Akihiro TakezawaAbstract:Topology Optimization has been successfully used in many industries, especially those engaged in the design and manufacturing of mechanical devices, but numerical problems are often encountered, such as grayscale representations of obtained composites. A type of structural Optimization Method using the level set theory for boundary expressions has been proposed, in which the outlines of target structures are implicitly represented using the level set function, and optimal configurations are obtained by updating this function based on the shape sensitivities. Level set-based Methods typically have a drawback, however, in that topological changes that increase the number of holes in the material domain are not allowed. To overcome the above numerical and topological problems, this paper proposes a new topology Optimization Method incorporating level set boundary expressions based on the concept of the phase field Method, which we apply to a minimum mean compliance problem. First, a structural Optimization problem is formulated based on a boundary expression, using the level set function. Next, a time evolutionary equation for updating the level set function is formulated based on the concept of the phase field Method, and the minimum mean compliance problem is formulated using a level set boundary expression. An Optimization algorithm for the topology Optimization incorporating the level set boundary expression based on the concept of the phase field Method is then derived. Several examples are provided to confirm the usefulness of the proposed structural topology Optimization Method.
Masaki Otomori - One of the best experts on this subject based on the ideXlab platform.
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matlab code for a level set based topology Optimization Method using a reaction diffusion equation
Structural and Multidisciplinary Optimization, 2015Co-Authors: Masaki Otomori, Kazuhiro Izui, Takayuki Yamada, Shinji NishiwakiAbstract:This paper presents a simple Matlab implementation for a level set-based topology Optimization Method in which the level set function is updated using a reaction diffusion equation, which is different from conventional level set-based approaches (Allaire et al. 2002, 2004; Wang et al. 2003) that use the Hamilton-Jacobi equation to update the level set function. With this Method, the geometrical complexity of optimized configurations can be easily controlled by appropriately setting a regularization parameter. We explain the code in detail, and also the derivation of the topological derivative that is used in the level set-based topology Optimization. Numerical results for stiffness maximization problems are provided to facilitate the reader's understanding. The presented code is intended for educational purposes only. This paper was inspired by previously published papers presenting Matlab code for a SIMP Method (Sigmund 2001; Andreassen et al. 2011), a level set-based Method (Challis 2010), and FreeFem ++ code for a structural Optimization Method (Allaire and Pantz 2006). Readers can investigate results provided by these different Methods and discover the prominent aspects of each particular Method. The code presented here can be downloaded from http://www.osdel.me.kyoto-u.ac.jp/members/yamada/codes.html.
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a topology Optimization Method based on the level set Method for the design of negative permeability dielectric metamaterials
Computer Methods in Applied Mechanics and Engineering, 2012Co-Authors: Masaki Otomori, Kazuhiro Izui, Shinji Nishiwaki, Takayuki Yamada, Jacob AndkjaerAbstract:Abstract This paper presents a level set-based topology Optimization Method for the design of negative permeability dielectric metamaterials. Metamaterials are artificial materials that display extraordinary physical properties that are unavailable with natural materials. The aim of the formulated Optimization problem is to find optimized layouts of a dielectric material that achieve negative permeability. The presence of grayscale areas in the optimized configurations critically affects the performance of metamaterials, positively as well as negatively, but configurations that contain grayscale areas are highly impractical from an engineering and manufacturing point of view. Therefore, a topology Optimization Method that can obtain clear optimized configurations is desirable. Here, a level set-based topology Optimization Method incorporating a fictitious interface energy is applied to a negative permeability dielectric metamaterial design problem. The Optimization algorithm uses the Finite Element Method (FEM) for solving the equilibrium and adjoint equations, and design problems are formulated for both two- and three-dimensional cases. First, the level set-based topology Optimization Method is explained, and the Optimization problems for the design of metamaterials are then discussed. Several optimum design examples for the design of dielectric metamaterials that demonstrate negative effective permeability at prescribed frequencies are provided to confirm the utility and validity of the presented Method.
Jianguo Zhu - One of the best experts on this subject based on the ideXlab platform.
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multiobjective system level Optimization Method for switched reluctance motor drive systems using finite element model
IEEE Transactions on Industrial Electronics, 2020Co-Authors: Kaikai Diao, Gang Lei, Youguang Guo, Xiaodong Sun, Jianguo ZhuAbstract:This article presents a novel multiobjective system level Optimization Method to achieve the best performance of switched reluctance motor (SRM) drive systems. First, the multiobjective Optimization problem for the SRM drive systems is defined. Then, all parameters of the drive systems, including the motor level and control level, are divided into three subspaces according to their influences on the objectives. Finally, the Optimization of each subspace is performed sequentially until a convergence criterion is met. Then, the optimal solution can be chosen from the Pareto solutions according to a selection criterion. Meanwhile, the sensitivity analysis, the approximate models, and the genetic algorithm are employed to reduce the computation cost. To verify the effectiveness of the proposed Method, an SRM drive system with a segmented-rotor SRM (SSRM) and the angle position control Method is investigated. This is a high-dimensional system level Optimization problem with ten parameters. The finite-element model (FEM) results are verified by the experiment results. The optimal solution has been listed and verified by the FEM. From the discussion, it can be found that the proposed Optimization Method is efficient and optimized SSRM drive system has high efficiency and low torque ripple.
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Multilevel Design Optimization of a FSPMM Drive System by Using Sequential Subspace Optimization Method
IEEE Transactions on Magnetics, 2014Co-Authors: Gang Lei, Youguang Guo, Jianguo Zhu, Kera ShaoAbstract:In our previous research, flux-switching permanent magnet machine (FSPMM) was investigated for the application in hybrid electric vehicles. To obtain the best performance of the whole drive system, a new multilevel design Optimization Method is presented for this kind of machine and a field oriented control system. The proposed multilevel Optimization Method is based on sequential subspace Optimization Method. In the implementation, three levels are employed to obtain the optimal design scheme at the system level. Meanwhile, sequential Optimization Method is employed to reduce the computation cost of finite element analysis on the motor level. Finally, from the design analysis, it can be found that the proposed Method can provide design scheme with better performance, while the needed computation cost is reduced greatly for this FSPMM drive system.
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multiobjective sequential Optimization Method for the design of industrial electromagnetic devices
IEEE Transactions on Magnetics, 2012Co-Authors: Gang Lei, Youguang Guo, Jianguo Zhu, X M Chen, K R ShaoAbstract:A multiobjective sequential Optimization Method (MSOM) is presented to deal with practical design problems of industrial electromagnetic devices. MSOM consists of a sequential Optimization strategy of multiobjective Optimization model and a modified central composite design (CCD) sampling Method. To improve the Optimization efficiency, Kriging model is employed to construct the approximate multiobjective Optimization models. Then a modified CCD sampling Method is presented to update the sample sets with the obtained Pareto optimal points and Kriging models. Thereafter, by investigating a test function and a three-dimensional permanent magnet transverse flux machine, it can be found that the proposed Method is efficient, and the computation cost of finite element analysis can be saved remarkably.
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sequential subspace Optimization Method for electromagnetic devices design with orthogonal design technique
IEEE Transactions on Magnetics, 2012Co-Authors: Gang Lei, Youguang Guo, Jianguo Zhu, X M Chen, K R ShaoAbstract:We present two new sequential Optimization strategies, a sequential subspace Optimization Method (SSOM) and an improved sequential Optimization Method (SOM) with orthogonal experimental design technique, to deal with Optimization design problems of electromagnetic devices in this work. To implement the proposed Methods, we first divide the whole design factors into three sets, namely highly-significant, significant, and nonsignificant factors. Then the whole design space can be correspondingly divided into three subspaces with these three sets of factors. Thereafter, SSOM is presented to sequentially optimize those subspaces. In the subspace, we present an improved SOM based on orthogonal experimental design technique to get optimal solutions. Finally, by investigating TEAM benchmark problem 22, we can see that the sampling efficiency can be improved significantly and the computational cost of finite element analysis can be saved remarkably by the proposed Methods.
