This paper focuses on saddle point problems with a 2-by-2 block coefficient matrix. When the number of columns in the upper-right block and the number of rows in the lower-left block of the coefficient matrix is large, the convergence behavior of Krylov subspace methods for the saddle point problems tends to be poor even if the upper-left block is a well-conditioned matrix. In this paper, an efficient approach for solving the saddle point problems using block structure of the problems is proposed. The most time-consuming part of our proposed approach is the solution of a linear system with multiple right-hand sides. To solve the linear system with multiple right-hand sides efficiently, we propose to apply Block Krylov subspace methods to this linear system. Numerical experiments show that the proposed approach with Block Krylov subspace methods can solve the saddle point problems more efficiently than the conventional approach in terms of the number of iterations and the computation time.
{"title":"An efficient approach for solving saddle point problems using block structure","authors":"Hiroto Tadano, Shota Ishikawa","doi":"10.15748/JASSE.8.114","DOIUrl":"https://doi.org/10.15748/JASSE.8.114","url":null,"abstract":"This paper focuses on saddle point problems with a 2-by-2 block coefficient matrix. When the number of columns in the upper-right block and the number of rows in the lower-left block of the coefficient matrix is large, the convergence behavior of Krylov subspace methods for the saddle point problems tends to be poor even if the upper-left block is a well-conditioned matrix. In this paper, an efficient approach for solving the saddle point problems using block structure of the problems is proposed. The most time-consuming part of our proposed approach is the solution of a linear system with multiple right-hand sides. To solve the linear system with multiple right-hand sides efficiently, we propose to apply Block Krylov subspace methods to this linear system. Numerical experiments show that the proposed approach with Block Krylov subspace methods can solve the saddle point problems more efficiently than the conventional approach in terms of the number of iterations and the computation time.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67361529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Susumu Fujiwara, Ryuta Kawanami, Haolun Li, Hiroaki Nakamura, K. Omata
. Molecular dynamics simulations of the hydrogen-removed polyethylene are carried out to study the structural change of polyethylene induced by beta decays of substituted tritium. Our simulations show that the folded structure of the hydrogen-removed polyethylene becomes more disordered as the number of removed hydrogen atoms becomes larger. We also propose a theoretical approach to explaining and predicting our molecular dynamics simulation results of hydrogen-removed polyethylene on the basis of the linear response theory. We derive the time derivative of the dynamical quantity, which is conjugate to the force applied as perturbation in the framework of the linear response theory, required to calculate the response function. The dynamical quantity in this study is the total potential energy difference of polyethylene before and after removal of hydrogen. Preliminary results of the response function for the total potential energy of polyethylene after removal of hydrogen are presented.
{"title":"A theoretical approach to structural change of a polymer induced by beta decays of substituted tritium based on the linear response theory","authors":"Susumu Fujiwara, Ryuta Kawanami, Haolun Li, Hiroaki Nakamura, K. Omata","doi":"10.15748/jasse.8.211","DOIUrl":"https://doi.org/10.15748/jasse.8.211","url":null,"abstract":". Molecular dynamics simulations of the hydrogen-removed polyethylene are carried out to study the structural change of polyethylene induced by beta decays of substituted tritium. Our simulations show that the folded structure of the hydrogen-removed polyethylene becomes more disordered as the number of removed hydrogen atoms becomes larger. We also propose a theoretical approach to explaining and predicting our molecular dynamics simulation results of hydrogen-removed polyethylene on the basis of the linear response theory. We derive the time derivative of the dynamical quantity, which is conjugate to the force applied as perturbation in the framework of the linear response theory, required to calculate the response function. The dynamical quantity in this study is the total potential energy difference of polyethylene before and after removal of hydrogen. Preliminary results of the response function for the total potential energy of polyethylene after removal of hydrogen are presented.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67361786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. Our work aims to interpret historical documents in closed booklet form without physical unfolding through CT scanning techniques. X-ray based CT scans can transform booklets into physical data for analysis, and current research in this direction performs page segmentation at the two-dimensional level and does not analyze data from historical documents at the three-dimensional level. Our proposed method uses a self-developed web tool for 3D dimensional annotation and solves Laplace’s equation to construct the 3D spatial structure of historical documents and perform page segmentation. We experiment with data in booklet form and show how to segment and extract pages in three dimensions by using Laplace’s equation.
{"title":"Three-dimensional book data page segmentation and extraction method using Laplace equation","authors":"Jiarui Ou, Zhongjiang Han, K. Koyamada","doi":"10.15748/jasse.8.223","DOIUrl":"https://doi.org/10.15748/jasse.8.223","url":null,"abstract":". Our work aims to interpret historical documents in closed booklet form without physical unfolding through CT scanning techniques. X-ray based CT scans can transform booklets into physical data for analysis, and current research in this direction performs page segmentation at the two-dimensional level and does not analyze data from historical documents at the three-dimensional level. Our proposed method uses a self-developed web tool for 3D dimensional annotation and solves Laplace’s equation to construct the 3D spatial structure of historical documents and perform page segmentation. We experiment with data in booklet form and show how to segment and extract pages in three dimensions by using Laplace’s equation.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"230 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67361872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. Water level prediction is becoming increasingly important. However, physical models tend to become difficult to apply when it comes to some small rivers which have insufficient hydrological data. To address it, nowadays, deep learning methods are increasingly being applied to climate prediction analysis as an alternative to computationally expensive physical models for its features of flexible data-driven learning and universality. In our paper, we focus on the precipitation-only water level forecasting problem by using long-short-term memory (LSTM) based hybrid model, and try predicting the future water level of all the rivers in Japan by using simulated precipitation data from the database for Policy Decision making for Future climate change (d4PDF).
{"title":"LSTM Based Hybrid Method for Basin Water Level Prediction by Using Precipitation Data","authors":"Shuofeng Liu, Lei Puwen, K. Koyamada","doi":"10.15748/JASSE.8.40","DOIUrl":"https://doi.org/10.15748/JASSE.8.40","url":null,"abstract":". Water level prediction is becoming increasingly important. However, physical models tend to become difficult to apply when it comes to some small rivers which have insufficient hydrological data. To address it, nowadays, deep learning methods are increasingly being applied to climate prediction analysis as an alternative to computationally expensive physical models for its features of flexible data-driven learning and universality. In our paper, we focus on the precipitation-only water level forecasting problem by using long-short-term memory (LSTM) based hybrid model, and try predicting the future water level of all the rivers in Japan by using simulated precipitation data from the database for Policy Decision making for Future climate change (d4PDF).","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67361951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Saito, Hiroaki Nakamura, T. Kenmotsu, Y. Oya, Y. Hatano, Y. Tamura, Susumu Fujiwara, H. Ohtani
. The number of double - strand breaks can be evaluated from the change of average DNA length. The average DNA length is measured by the single - molecule observation method using fluorescence microscope. The measurement of DNA length in the microscope images is done manually by experienced operators and it is time consuming in many experi-ments. An image processing method using OpenCV library to measure length of DNA in fluorescence microscope images is developed in this paper. An automation of measurement using deep learning is also proposed.
{"title":"Image processing method for automatic measurement of number of DNA breaks","authors":"S. Saito, Hiroaki Nakamura, T. Kenmotsu, Y. Oya, Y. Hatano, Y. Tamura, Susumu Fujiwara, H. Ohtani","doi":"10.15748/jasse.8.173","DOIUrl":"https://doi.org/10.15748/jasse.8.173","url":null,"abstract":". The number of double - strand breaks can be evaluated from the change of average DNA length. The average DNA length is measured by the single - molecule observation method using fluorescence microscope. The measurement of DNA length in the microscope images is done manually by experienced operators and it is time consuming in many experi-ments. An image processing method using OpenCV library to measure length of DNA in fluorescence microscope images is developed in this paper. An automation of measurement using deep learning is also proposed.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67362126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. The purpose of this study is an improvement of convergence properties of an interface problem in the high-frequency electromagnetic field finite element analysis based on the iterative domain decomposition method by introducing a pseudo-quadruple precision into the subdomain solver. In the high-frequency electromagnetic field analysis, it is well known that when the numerical model becomes huge scale, the convergence properties of the interface problem become extremely poor. To improve the deterioration of the convergence property in the interface problem, we propose to introduce a pseudo-quadruple precision into the iterative solver based on the conjugate gradient method in the subdomain problem. The pseudo-quadru-ple precision is constructed by ordinary double precisions. In this study, we apply the pseudo-quadruple precision for solving subdomain problems in the iterative domain decomposition method. As a result, we can obtain improvement of convergence properties in the iterative solver for the interface problem.
{"title":"High-frequency electromagnetic field analysis using pseudo-quadruple precision in subdomain local solver","authors":"A. Takei, H. Kawai, R. Shioya, Tomonori Yamada","doi":"10.15748/jasse.8.194","DOIUrl":"https://doi.org/10.15748/jasse.8.194","url":null,"abstract":". The purpose of this study is an improvement of convergence properties of an interface problem in the high-frequency electromagnetic field finite element analysis based on the iterative domain decomposition method by introducing a pseudo-quadruple precision into the subdomain solver. In the high-frequency electromagnetic field analysis, it is well known that when the numerical model becomes huge scale, the convergence properties of the interface problem become extremely poor. To improve the deterioration of the convergence property in the interface problem, we propose to introduce a pseudo-quadruple precision into the iterative solver based on the conjugate gradient method in the subdomain problem. The pseudo-quadru-ple precision is constructed by ordinary double precisions. In this study, we apply the pseudo-quadruple precision for solving subdomain problems in the iterative domain decomposition method. As a result, we can obtain improvement of convergence properties in the iterative solver for the interface problem.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67362229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. We derive analytic expressions for the vector potential of electromagnetic wave radiated from a relativistic electron moving on a spiral orbit under an approximation that the velocity along the spiral orbit is much larger than that perpendicular to the axis. Based on this expression, we show that the electromagnetic wave has a spiral wave front and carries angular momentum.
{"title":"Spatial structure and angular momentum of electro-magnetic wave radiated from a relativistic electron moving on a spiral orbit","authors":"E. Salehi, M. Katoh","doi":"10.15748/JASSE.8.87","DOIUrl":"https://doi.org/10.15748/JASSE.8.87","url":null,"abstract":". We derive analytic expressions for the vector potential of electromagnetic wave radiated from a relativistic electron moving on a spiral orbit under an approximation that the velocity along the spiral orbit is much larger than that perpendicular to the axis. Based on this expression, we show that the electromagnetic wave has a spiral wave front and carries angular momentum.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67362552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. In this paper, a novel topology optimization method, in which gaussian filter is selected as spatial smoothing method, is presented. By changing standard deviation parameter, strength of filtering operation can be adjusted in the present method. Thanks to this, optimum solution, shape of which has multi-layer shield structure and multi-layer flux barrier, can be obtained. To validate the effectiveness, the present method is applied to shape optimization problem of magnetic shield and synchronous reluctance motor. From the results, it can be seen that the present method can get better solutions than that of the conventional method.
{"title":"Topology optimization of electrical devices using Gaussian filter","authors":"Y. Hidaka, Hidenori Sasaki","doi":"10.15748/JASSE.8.98","DOIUrl":"https://doi.org/10.15748/JASSE.8.98","url":null,"abstract":". In this paper, a novel topology optimization method, in which gaussian filter is selected as spatial smoothing method, is presented. By changing standard deviation parameter, strength of filtering operation can be adjusted in the present method. Thanks to this, optimum solution, shape of which has multi-layer shield structure and multi-layer flux barrier, can be obtained. To validate the effectiveness, the present method is applied to shape optimization problem of magnetic shield and synchronous reluctance motor. From the results, it can be seen that the present method can get better solutions than that of the conventional method.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67362596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuya Hanaoka, T. Itoh, K. Tateyama, S. Nakata, Keiko Watanabe
. Recently, to generate metal foam models for either open or closed state, a sphere-function-based method and a radial-basis-function-based one have been proposed. In these methods, implicit functions are employed for representing shapes of metal foams. In this pa-per, these methods based on spheres and radial basis functions have similarly been extended by employing characteristics of implicit functions, so that open / closed states and their intermediates can be represented. It is an advantage of the extended methods that any states of metal foams can be represented by only one implicit function.
{"title":"Shape Modelling of Metal Foams of Open/Closed States and their Intermediates by Implicit Function","authors":"Yuya Hanaoka, T. Itoh, K. Tateyama, S. Nakata, Keiko Watanabe","doi":"10.15748/JASSE.8.143","DOIUrl":"https://doi.org/10.15748/JASSE.8.143","url":null,"abstract":". Recently, to generate metal foam models for either open or closed state, a sphere-function-based method and a radial-basis-function-based one have been proposed. In these methods, implicit functions are employed for representing shapes of metal foams. In this pa-per, these methods based on spheres and radial basis functions have similarly been extended by employing characteristics of implicit functions, so that open / closed states and their intermediates can be represented. It is an advantage of the extended methods that any states of metal foams can be represented by only one implicit function.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67361912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. A fast linear solver for topology optimization using a deflation technique with Proper Orthogonal Decomposition (POD) is discussed. The topology optimization method based on evolutionary algorithms requires huge computational cost. In this reason, a deflated Preconditioned Conjugate Gradient (PCG) method is introduced so as to reduce the cost of finite element analysis. The deflation technique decomposes the solution into fast and slowly converging components. The slow components can be solved by direct methods with low computational cost due to small dimensions. Therefore, the deflated PCC method can improve the convergence of PCG. However, the deflated PCG requires to find the slow components. In this study, a POD method with snapshots is introduced. In the optimization process, solution vectors corresponding to parents are used for the snapshots. Orthogonal vectors for the deflation are constructed from the snapshots. Numerical results show that the present method can reduce the computational cost.
{"title":"Fast deflated conjugate gradient method with proper orthogonal decomposition for topology optimization","authors":"Kota Watanabe, Kaito Oshima","doi":"10.15748/JASSE.8.154","DOIUrl":"https://doi.org/10.15748/JASSE.8.154","url":null,"abstract":". A fast linear solver for topology optimization using a deflation technique with Proper Orthogonal Decomposition (POD) is discussed. The topology optimization method based on evolutionary algorithms requires huge computational cost. In this reason, a deflated Preconditioned Conjugate Gradient (PCG) method is introduced so as to reduce the cost of finite element analysis. The deflation technique decomposes the solution into fast and slowly converging components. The slow components can be solved by direct methods with low computational cost due to small dimensions. Therefore, the deflated PCC method can improve the convergence of PCG. However, the deflated PCG requires to find the slow components. In this study, a POD method with snapshots is introduced. In the optimization process, solution vectors corresponding to parents are used for the snapshots. Orthogonal vectors for the deflation are constructed from the snapshots. Numerical results show that the present method can reduce the computational cost.","PeriodicalId":41942,"journal":{"name":"Journal of Advanced Simulation in Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67362001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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