著者

幸谷 智

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会論文誌 (ISSN:18835031)

巻号頁・発行日

vol.8, no.2, pp.67-71, 2016 (Released:2016-06-29)

参考文献数

9

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At rifle shooting, some adjustments on a riflescope, called “zeroing”, are required for precise aiming, and done with multiple trial fires. It is a matter of course that more trial shots make zeroing more correctly. However, no conventional data could be found to know how many trials make zeroing how accurately. There are some limits for firing a large amount of ammunition, to know the fact, causing not only budget but legal. Therefore, a distribution of bullet marks is analyzed at the setout, and it is ascertained that follows gauss distribution. Following simulations are based on that fact. Differences between bullet marks and the center of crosshair are normalized with their standard deviation to make relation free from shooter's skills, machining accuracies, and such shooting environments. Required numbers of trial shot are calculated to achieve arbitrary accuracies conclusively.

著者

Susumu Fujiwara Hiroaki Nakamura Haolun Li Hisanori Miyanishi Tomoko Mizuguchi Takuo Yasunaga Takao Otsuka Yuji Hatano Shinji Saito

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.6, no.1, pp.94-99, 2019 (Released:2019-03-15)

参考文献数

9

被引用文献数

3 8

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We propose a computational strategy for investigating structural change of tritium-substituted macromolecules. Effects of radiation on macromolecules such as polymeric materials and DNA are classified into three categories: (1) direct action, (2) indirect action, and (3) decay effect. In this study, we focus on the decay effect exclusively. After a beta decay of substituted tritium in macromolecules to helium-3, the generated inert helium-3 is assumed to be deleted quickly. To get an insight into the decay effect to the damage of macromolecules, we perform molecular dynamics simulations of tritium-deleted macromolecules and analyze their structural change. Preliminary simulation results of decay effect on polymeric materials and DNA are presented.

著者

阿部 譲司 塩出 亮 藤野 清次

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会論文誌 (ISSN:18835031)

巻号頁・発行日

vol.7, no.1, pp.27-35, 2015

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The Crout variant of ILU preconditioner devised recently has been to have some advan-tages over conventional row-based ILU preconditioner. One of advantages is to be able to adopt a dropping strategy for estimating column norm of inverse <i>U</i>⁻¹. This paper shows how to extend this inverse-based dropping strategy to solve a linear system of equations with symmetric positive definite matrix. Furthermore this paper reveals significant characteristics of inverse-based dropping strategy through numerical experi-ments.<br>

著者

Michiaki Arita Sergiu Arapan David R. Bowler Tsuyoshi Miyazaki

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.1, no.1, pp.87-97, 2014 (Released:2014-10-31)

参考文献数

24

被引用文献数

15 22 1

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In oder to realize the DFT simulations on large-scale complex systems, we have been developing a linear-scaling DFT code Conquest. In this paper, we report the parallel efficiency of the code on K-computer and show that it has almost ideal parallel efficiency even when we use more than 200,000 cores. Using the code on such large-scale parallel computers, we are now ready to do actual DFT study on million-atom systems. By showing our current study on the nucleation of Ge dimers on three-dimensional Ge nano-islands on Si(001), we demonstrate that accurate, efficient and robust structure relaxation based on the DFT is possible in the actual scientific research on complex nano-structured materials.

著者

Yuya Hanaoka Momoko Nojiri Taku Itoh Susumu Nakata Keiko Watanabe

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.6, no.1, pp.195-214, 2019 (Released:2019-05-30)

参考文献数

10

被引用文献数

2

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To construct a model of metal foam that has rounded cells such as a real one, an implicit surface based modelling method has been proposed. In this method, uniformed points are first generated randomly by Poisson-disk sampling, and a Voronoi diagram is constructed from the points. In addition, an implicit function f (x) is generated in each of Voronoi cells by setting some constraints appropriately. An implicit surface is represented as f (x) = 0, and the constraints are set so that f (x) = 0 is generated inside each of Voronoi cells. In this model, walls of metal foam are represented by space between implicit surfaces of adjacent Voronoi cells. Rounded walls that have various thicknesses can be constructed by adjusting the constraints. In addition, the walls can be converted to a solid model constructed as tetrahedra filling the space.

著者

山本 広太 工藤 彰洋 武居 周

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会論文誌 (ISSN:18835031)

巻号頁・発行日

vol.9, no.2, pp.27-37, 2017 (Released:2017-06-23)

参考文献数

22

被引用文献数

2

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Currently, in the design and evaluation of acoustic environments such as concert halls and live houses, the importance of acoustic analysis technology is increasing due to the dramatic performance improvement of computers in recent years. Due to the large-scale of the analysis area and expansion of the analysis frequency band, it is necessary to solve the large scale problem more than before in the wave acoustic analysis. Therefore, in this research, we are researching and developing a large-scale sound field analysis method based on the parallel finite element method. The iterative domain decomposition method is employed in the analysis method as parallel technique. In this research, pre-conditioners for the interface problem in the iterative domain decomposition method are considered. As a result, we have found that the balancing domain decomposition method is the most effective acoustical analysis. We also confirmed that the acoustic analysis code is very high accuracy with errors within the allowable range in a numerical analysis.

著者

Yuji Hatano Hiroto Shimoyachi Tatsuya Asano Takahiro Kenmotsu Takuro Wada Yasuhisa Oya Hiroaki Nakamura Susumu Fujiwara

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.9, no.1, pp.198-205, 2022 (Released:2022-06-17)

参考文献数

12

被引用文献数

1

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The goal of this study is to establish a simple experimental system to examine the rate of double strand breaks (DSBs) of genome-sized DNA molecules under irradiation of β-rays from tritium under well-controlled conditions for the validation of computer simulation on interactions of biomolecules and ionizing radiation. Irradiation effects were insignificant at tritium concentration of 1300 Bq/cm3, indicating that the effects of β-rays were far smaller than those of oxidation and/or thermal motion at the low dose rate (4.3 μGy/h). Clear increase in DSB rate was observed at tritium concentrations of 3.0—4.0 MBq/cm3. The temperature dependence of DSB rate was examined by using the high concentration tritiated water.

著者

Hiroshi Serizawa Takashi Amemiya Kiminori Itoh

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.10, no.2, pp.221-246, 2023 (Released:2023-12-08)

参考文献数

43

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We present a minimal version of Landscape Evolution Models (LEMs) to capture the essence of tree-shaped channel network formation on the assumption of two mechanisms, soil erosion and diffusion. The continuous tectonic uplift is not required, which affects landscape evolution only at the starting point. We refer to the mathematical model as the Erosion-Diffusion Model (EDM). No steady state exists in the EDM except for the perfectly flat plane, which is realized at the ultimate final stage of the landform transition. It is suggested that generated channel patterns are temporal and transient creatures during long-term gravitational and erosional processes on the earth.

著者

井前 讓 品川 健次郎 上田 敦史 小林 友明 翟 貴生

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会論文誌 (ISSN:18835031)

巻号頁・発行日

vol.3, no.1, pp.11-17, 2011 (Released:2011-07-28)

参考文献数

16

被引用文献数

1

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We propose a new approach to obtain the solutions of HJB equations. Firstly, based on a simple but unique idea, we transform the conventional HJB equations into the virtual-time HJB equations (VT-HJB). As the virtual time goes by, the solution of the VT-HJB equations becomes that of the conventional ones. Then, we solve the VT-HJB equations with respect to the virtual time by means of existing differential equation solvers. Lastly, we demonstrate the effectiveness of our method through numeric experiments with linear and nonlinear control problems.

著者

Tomohoiro Tanaka Hidekazu Yoshioka

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.4, no.2, pp.162-175, 2017 (Released:2018-06-30)

参考文献数

21

被引用文献数

1 3

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The local inertial equation (LIE) as a simple mathematical model has been widely used for flood simulation. So far, the maximum allowable time step of the discretized LIE with the conventional semi-implicit scheme has been believed to follow the standard Courant-Friedrichs-Lewy condition. However, we demonstrate that this is not true from the viewpoint of a numerical stability analysis considering the model non-linearity. In addition, a fully-implicit variant of the scheme with higher stability is presented, indicating its practical advantages.

著者

後藤 和哉 橋本 学 奥田 洋司

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会論文誌 (ISSN:18835031)

巻号頁・発行日

vol.7, no.1, pp.1-9, 2015 (Released:2015-05-13)

参考文献数

17

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In this study, we investigated the convergence of parallel iterative linear solvers in structural finite element analyses with multipoint constraints (MPCs) treated by implicit and explicit master-slave elimination. Iterative linear solvers are indispensable in large-scale analyses due to its superior parallel scalability compared to direct solvers. For stable convergence of iterative linear solvers, it is important not to deteriorate condition of matrices when imposing MPCs. We previously proposed an implicit implementation of master-slave elimination, MPC-CG method, which had a drawback that it is difficult to implement effective preconditioners. In this paper, we compared MPC-CG method and explicit master-slave elimination by estimating condition numbers of preconditioned matrices, and by studying convergence of preconditioned iterative linear solvers. The results showed that the explicit elimination provided better convergence than the MPC-CG method. It was also observed that the overhead for explicit computation of matrix to be solved was small enough with respect to the total solution time. It was concluded that the explicit masterslave elimination is effective when iterative linear solvers are used for large problems with MPCs.

著者

Ran Dong Daisuke Shigeta Yoshihisa Fujita Soichiro Ikuno

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.9, no.1, pp.65-77, 2022 (Released:2022-02-08)

参考文献数

18

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Photonic crystals are widely employed in industry fields due to their bandgap property, which can confine and propagate electromagnetic waves inside the structure as a photonic waveguide. As this property can be adopted to propagate distinct frequency waves by changing the photonic structure, photonic crystals are also applied in frequency demultiplexer design. The finite-difference time-domain (FDTD) method is commonly applied to simulate electromagnetic wave propagations in photonic crystals, helping determine the desired bandgaps for frequency demultiplexers. Meanwhile, the multivariate empirical mode decomposition (MEMD) nonlinearly decomposes multivariate signals in the instantaneous frequency domain. Therefore, MEMD can verify and visualize the designed frequency demultiplexer made of photonic crystals by considering simulation results as a multi-channel signal. This research aims to propose a method to design and evaluate frequency demultiplexers using FDTD and MEMD. In this paper, photonic crystal bandgaps are adopted to design a frequency demultiplexer to separate two different frequency electromagnetic waves. Then, MEMD is employed to the result of frequency demultiplexer propagation simulated by FDTD. Our results reveal that the frequency demultiplexer made of photonic crystals can be designed using the bandgap properties, and its simulation results by FDTD method can be verified and visualized in the instantaneous frequency domain using MEMD.

著者

Yuya Hanaoka Taku Itoh Kohei Tateyama Susumu Nakata Keiko Watanabe

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会英文誌 (ISSN:21885303)

巻号頁・発行日

vol.8, no.1, pp.143-153, 2021 (Released:2021-06-12)

参考文献数

11

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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 paper, 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.

著者

武居 周 室谷 浩平 吉村 忍 金山 寛

出版者

Japan Society for Simulation Technology

雑誌

日本シミュレーション学会論文誌 (ISSN:18835031)

巻号頁・発行日

vol.4, no.3, pp.81-95, 2012 (Released:2012-12-15)

参考文献数

27

被引用文献数

3

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This paper describes a method of making mesh models for large-scale full-wave analysis of electromagnetic fields by the finite element method with an iterative domain decomposition method using numerical human body models. Numerical human body models by National Institute of Information and Communications Technology (NICT) composed by the voxel data with all sides of 2mm include skins, blood vessels, bones etc. and internal organs distinguishing with the material flag. The user can evaluate electromagnetic filed distribution inside the body using NICT numerical human models. A stationary vector wave equation for the 3D full-wave electromagnetic field analysis is solved taking an electric field as an unknown function. The mesh is efficiently divided by using the domain decomposition data structure when elements of 200 million or more are generated from the voxel data of NICT numerical human body models. The mesh generation method corresponds to a past 32-bit I/O library in the ADVENTURE System. Numerical analyses are done using torso models and whole body models. The results prove that our method can precisely predict the distribution of the electromagnetic field in human bodies inside.