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

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

土田 陽平 齋藤 誠紀 中村 浩章 米谷 佳晃 藤原 進

出版者

日本シミュレーション学会

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.13, no.1, pp.32-36, 2021 (Released:2021-06-15)

参考文献数

12

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福島第一原子力発電所の廃炉に伴いトリチウム水の海洋放出が検討されている.また,将来の発電技術として期待されている核融合発電では,トリチウムを燃料として用いる.そのため,トリチウムの生体への影響を詳細に解明することが求められている.我々は,ヒトDNA中の軽水素がトリチウムに置換した際に生じる壊変効果がDNAを損傷するメカニズムを,分子動力学法を用いて解明することを目指している.壊変効果の影響を理解するためには,まずDNA中の各々の軽水素について,トリチウム置換のしやすさを評価する必要がある.そこで本研究では,ヒトDNAテロメア構造のバックボーン中に存在する水素原子を対象に,トリチウム置換のしやすさの指標を得るために分子動力学計算を実施し,各水素の溶媒接触表面積を計算した.計算結果から,バックボーン中の水素原子の中ではH5の水素の溶媒接触表面積が大きいことが判明した.

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

石田 武志

出版者

日本シミュレーション学会

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.2, pp.51-61, 2012 (Released:2012-11-23)

参考文献数

13

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Renewable energy resources are generally unstable and affect the performance of electricity grids when they are fully connected. A distributed energy supply network system is expected to overcome the above problem. Such a system consists of a network system in which electricity and heat can be transferred between dispersion generators and the renewable energy resources and can supply stable energy to an urban district. We have constructed a self-organization model for the formation of dispersion energy network. We demonstrated that the following 2 functions can be realized by the multi-agent model which has rules for introduction of energy facilities (fuel cell cogeneration system (CGS), heat pump system (HP), photovoltaic (PV) systems and conventional system). 1) Energy exchange was achieved between neighbor houses and surplus energy was consumed in urban district. 2) “Energy colony” is formed for self-organizing.   Our simulation results indicated that stable energy exchange was possible when “Energy colony” was formed in the district. It is considered that it is possible to construct self-organization energy network in a real dynamic urban energy environment by applying the facility replacement rules determined in this study.

著者

中野 博生 轟木 義一 多田野 寛人

出版者

日本シミュレーション学会

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.15, no.2, pp.56-63, 2023 (Released:2023-09-13)

参考文献数

10

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MPIに基づいて並列化したジョブでプロセス数が多いものを富岳で実行したときの挙動を調べた.特に,ジョブのメモリ消費量の変化に注目する.MPIプロセス数が大きい場合,MPIの初期化の実行で少なくないメモリ消費が発生,増加していく.並列化度がさらに大きくなると,ジョブは最終的にメモリ枯渇に至る.その結果我々は,富岳で全系実行を行う場合でも実現できるMPI並列数は最大で約350万であることを明らかにした.MPIの並列度数は使用する計算ノード数に応じて設定する必要があるが,富岳の大規模ジョブとして実行する場合,ユーザーのコードに明示的に記述して利用できるメモリがかなり制限されることに注意が必要であることも明らかにした.

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

楊 陽 奈良 知恵 萩原 一郎

出版者

日本シミュレーション学会

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.11, no.1, pp.1-13, 2019 (Released:2019-05-11)

参考文献数

20

被引用文献数

1

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In the earthquake, the helmets play an important role in protecting the head of people, so the helmet needs to be less than 300 mm×200 mm×50 mm and should be put in the emergency bag for the time being. The existing helmets can't satisfy the requirement. In order to achieve the target, a foldable helmet is inspired by Origami engineering. Based on the MHLW helmet standards, a foldable helmet consisting of accordion cover origami structure/honeycomb origami structure is applied and the impact characteristic of the foldable helmet is investigated by FEM analyses and experiments. On the basis of this new foldable origami helmet that has been confirmed in satisfying the requirements of saving and safety, in order to make the foldable origami helmet be used for infants, the RSO structure is added. Finally, the improved helmet satisfied higher safety standards and could be put in the small box at the same time.

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

伊藤 建一

出版者

日本シミュレーション学会

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.13, no.1, pp.1-10, 2021 (Released:2021-01-29)

参考文献数

18

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This study evaluated the signal transmission characteristics, the electromagnetic field distributions in and around the human body, and the biosafety criteria of magnetically coupled intra-body communication through computer simulation. The analyzed magnetic couplings were a normal inductive coupling (non-resonant coupling) and two types of resonant couplings. The target evaluation regions were the forearm and upper body, and we analyzed up to an inter-coil distance of 100 cm, which is considered to be the assumed human body communication range. The results of the frequency characteristics of the signal path loss, which were the same as before, revealed that the amount of signal loss for the inductive coupling was minimized between 2 and 3 MHz at each coil distance; one of the resonant couplings could improve the signal path loss by approximately 20 dB at a resonant frequency of 2 MHz. Furthermore, when the signal voltage was 1 V, the electric field strength in the body was smaller than the general environmental limit value by more than two orders of magnitude. The local specific absorption rate was smaller by approximately four orders of magnitude; thus, it was concluded that the magnetic field method is very safe for the living body.

著者

市川 知春 武田 和大 原 崇

出版者

日本シミュレーション学会

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.13, no.2, pp.83-91, 2021 (Released:2021-08-31)

参考文献数

10

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インターネットショッピングのレビュー機能は,購入者が商品の感想や評価を記入できる機能である.購入希望者は商品レビューを読んで,事前に商品の情報を得ることができる.しかし,すべての購入者が注意深くレビューを書かないため,参考にならない商品レビューも存在する.本研究では機械学習を用いた自然言語処理にて商品レビューの解析,評価を行い,参考になる順番に並び替えを行うシステムを構築する.レビューの内容に登場する回数が多いものを学習素性とし,学習素性が商品レビューの内容に影響する重みを算出して,適切な重みを求めるように,ロジスティック回帰を用いて学習を行う.システムの評価には,クイックソートを利用した評価法であるQE法を提案する.QE法を使用することで,正しく並び替えができているかどうかの評価を行うことができた.実験の結果,提案するシステムは,高い精度で商品レビューの並び替えが行えることを確認できた.

著者

小林 知嵩 内藤 健

出版者

日本シミュレーション学会

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.13, no.1, pp.18-22, 2021 (Released:2021-05-25)

参考文献数

9

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自然界に存在する生命分子や原子核分裂直後の粒子対のサイズ比(質量比)の必然性を解明するために,流体力学的な近似モデルを拡張した確率論的運動量保存則のモデル(Naitoh:J. of Physics, 2012)が提示された.このモデルに1次元空間でのテイラー展開を施した後に,新たな安定性概念(最弱の安定性である準安定性)を適用することで,対称および非対称なサイズ比(質量比)が共存する理由が定性的に解明された.従来,原子核分裂については,エネルギー保存則に対してなされてきたが,この新たなモデルは,3次元非定常の運動量保存則によるもので,ベクトル量(速度)も扱っており,空間次元が高いことが特徴となっており,スカラー量のエネルギー保存則と比べて,より詳細なメカニズムの解明が期待できる.著者は,更に,多次元のテイラー展開を導入して,拡張した式とすることで,生命・非生命の粒子のサイズ,質量比の頻度分布を,従来よりも正確に求めることができることを示してきた.(Kobayashi and Naitoh, JASSE, 2019)しかも,多次元のテイラー展開を施した後にあらわれる項の群を,表面力系,対流系,中間系の3種に分類することで,ウラン235の核分裂反応における原子核内部の対流の強さ(つまり,衝突させる中性子のエネルギーレベル)が,生成される原子核の質量分布に影響するメカニズムも解明してきた.本研究では,この理論を凝縮系核反応にも適用する.投入するエネルギーレベルが小さいことを元に,表面力系および中間系の2種類の項の群を用いて反応生成物の質量分布計算を行った結果,凝縮系核反応の反応生成物の質量分布について,ある程度説明することができた.

著者

宮地 英生 川原 慎太郎

出版者

日本シミュレーション学会

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.12, no.2, pp.59-67, 2020 (Released:2020-07-23)

参考文献数

26

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Visualization is an extremely important technology for exploring and presenting various physical phenomena included in the simulation results and many scientific visualization applications have been developed since the latter half of the 1980s. In recent years, virtual reality (VR) visualization, which represents physical phenomena with complicated three-dimensional (3-D) structures in stereoscopic images to further facilitate their understanding, has attracted attention with a prevalence of VR technologies. However, most of them display the visualization results, which were exported as 3-D model data from the existing visualization application, on the VR devices. For this reason, it is necessary to re-export the 3-D model data every time the visualization parameter is changed. Therefore, we have developed a framework for completing a visualization workflow such as reading simulation data and applying visualization algorithms on the game engine which has been used for the development of applications for VR devices in recent years. The framework proposed in this paper is possible to build a VR visualization application without programming by connecting the visualization module appropriately on the visual interface of the game engine.

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.

著者

藤野 清次 小玉 捷平 岩里 洸介

出版者

日本シミュレーション学会

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.4, pp.79-83, 2015 (Released:2016-01-07)

参考文献数

7

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We consider reduction of cache miss which frequently occurs in the operations of Matrix-vector multiplication in case of nonzero entries stored using CCS format of edge-type of matrix. Edge-type of matrix often appears in the filed of superposition of FEM (Finite Element Method) analysis. The efficiency of iterative method as the Conjugate Gradient method depends on both mathematical convergence rate and implementation of Matrix-vector multiplication. In this paper, we propose zigzag CCS format for the store of nonzero entries of edge-type of matrix. Through numerical experiments, we examine that the proposed zigzag CCS format works well as compared with the conventional CCS format in case of edge-type of matrix.