担当区分：責任著者  

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担当区分：筆頭著者  

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担当区分：筆頭著者  

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担当区分：責任著者   記述言語：日本語  

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担当区分：責任著者   記述言語：日本語  

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担当区分：最終著者  

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語  

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）  

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担当区分：最終著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：責任著者  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Ken-yusha Inc.  

In order to evaluate the axial force of a continuous welded rail quantitatively in a simple manner, a method was developed to measure axial force based on the natural frequency. However, the accuracy of this method is insufficient because of certain variations in track condition. This study extracted factors which influence measurement accuracy and proposed an error correction method using track finite-element analysis for the purpose of improving the accuracy of this measuring method. Furthermore, measurements were taken of the natural frequency and axial force of a rail on a real track in order to validate the proposed method.

DOI： 10.2219/rtriqr.57.2_125

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

CiNii Article

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

構造物や民家に近接して発破掘削を行う場合，切羽外周部あるいは中央部にスロット，すなわち自由面を形成する制御発破（以下，自由面発破と呼ぶ）が行われるケースがある．自由面発破を実施した場合，発破振動を大幅に低減できることが知られているが，その効果について定性的かつ定量的な議論はほとんどなされていない．自由面発破における動的破壊と振動の挙動が明らかになっていないことと，これらを適切に評価できる数値解析手法が確立されていないためと考えられる． 筆者らは個別要素解析にもとづいた動的破壊と振動とを評価する解析手法を提案している．本研究では，自由面発破の合理的な設計を目的として，コンクリート試験体を用いた発破実験により実現象としての破壊挙動を明らかにするとともに，数値解析手法によりその再現解析を試みることで，解析手法の妥当性について検証した．

DOI： 10.2208/jscejte.71.I_1

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記述言語：英語   出版者・発行元：一般社団法人日本機械学会  

The FE-based coupling method with ballast settlement elastoplastic analysis and track vibration analysis considering unsupported sleepers is developed to accurately evaluate the sleeper-ballast interaction force in deteriorated track. The present method is used to investigate the evolution of the ballast settlement around a junction of concrete slab and ballast layer. In the analysis considering unsupported sleepers, the maximum of the sleeper-ballast interaction force at the sleeper away from the junction increases in progression of the number of loading cycles at higher rate than that without loose sleepers. A larger maximum force causes a larger permanent deformation of ballast layer. This is because the progression of ballast settlement leads to an increase in the number of unsupported sleepers in neighborhood of a supported sleeper.

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記述言語：英語   出版者・発行元：一般社団法人日本機械学会  

The axial force of a continuous welded rail(CWR) causing buckling and break of the rail should be controlled appropriately and adequately. In order to measure the axial force of the CWR quantitatively and in a simple manner, a method of presuming the axial force based on detection of the change of the natural frequency according to the axial force is developed. However, the accuracy of this method is insufficient because not only the axial force but the variations of track conditions such as the state of the rail and the rail fastening devices affect the natural frequency of the rail. In this paper, to investigate the influence of the variations in track conditions and its correction method for accurate measurement, we develop a finite element track model. Numerical experiments show that the wear of the rail head and the variation of the sleeper bays in the range of approximately 30 meters around the measuring point affect the natural frequency. Furthermore, we measured the axial force and the natural frequency of the CWR under various temperature conditions in an actual track and compared them with the numerical results. Through these analyses, it was confirmed that the axial force is in proportion to the natural frequency. Moreover, the consideration of the wear of the rail head and the variation of the sleeper bays in the track makes it possible to reproduce the difference of the absolute value of the natural frequency between two measurement points. By contrast, the sensitivity of the natural frequency to the axial force in the experiment is higher than that of the numerical results. Furthermore, the sensitivity of the experimental results in winter is higher than that in summer.

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

格子間隔の異なる周期列を積層した複合材層を有する，無限動弾性場の二次元波動透過解析法を構成した．特に上下の複合材層の格子間隔の比が有理数で与えられる場合を対象に，Floquet変換援用の下，当該問題を各周期層を構成する1ユニットの動的問題に帰着して解く方法を採った．また，周期層に平面波が入射する問題を例に，本手法による波動透過解析を試みた．両周期層のストップバンドを異なる周波数帯に設定することで，より広い周波数域における透過波動の遮蔽が可能となることを確認した．

DOI： 10.2208/jscejam.71.I_859

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記述言語：英語   出版者・発行元：一般社団法人日本機械学会  

Parametric instability of a wheel moving at a constant speed on a railway track is discussed. For this purpose, this paper presents an analytical formulation in which the damping is considered in rail supports. Since the dynamic behavior of a railway track depends on the rail axial load arising from the temperature change, this effect is also taken into account in the present mathematical model. Through numerical analyses, it is found that the eigenvalue which characterizes the quasi-steady-state dynamic reaction of the moving wheel and track is translated toward the positive imaginary number under the existence of damping. The range of unstable velocity is then narrowed by the introduction of dissipation into the track structure. Moreover, the critical damping at which the instability zone vanishes is obtained. Although the compressional rail stress reduces the instability speed, its contribution to the critical damping is insignificant.

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記述言語：英語   出版者・発行元：一般社団法人日本機械学会  

A measuring method of rail axial load based on vibration modes is discussed. In particular, the influence of the thermal dependency of rubber pads on the natural frequency of the pinned-pinned mode is investigated. To this end, in the numerical track model a rotational spring is attached at each rail support. Through numerical experiments, it is found that the thermal dependency of the rotational stiffness dominates the sensitivity of the resonant frequency to the axial load, and its consideration is essential to simulate the dynamic nature of tracks. Furthermore, the identification of the temporal equivalent rotational stiffness reflecting the rail pad and fastener is attempted. Numerical results show that the identification using the ratio of bending moment to rotation angle of rail measured around the rail support has the best performance. In this case, the measurement with error of 0.1% is required to assure the identification accuracy of ±50kN.

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

The parametric instability of a wheel moving on a discretely supported rail is discussed. To achieve this, an analysis method is developed for a quasi-steady-state problem which can represent an exponential growth of oscillation. The temporal Fourier transform of the rail motion is expanded by a Fourier series with respect to the longitudinal coordinate, and then the response of the rail deflection due to a quasi-harmonic moving load is derived. The wheel/track interaction is formulated by the aid of this function and reduced to an infinite system of linear equations for the Fourier coefficients of the contact force. The critical velocities between the stable and unstable states are calculated based on the nontrivial condition of the homogeneous matrix equation. Through these analyses the influences of the modeling of rail and rail support on the unstable speed range are examined. Moreover, not only the first instability zone but also other zones are evaluated. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jsv.2014.03.027

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：KATHOLIEKE UNIV LEUVEN, DEPT WERKTUIGKUNDE  

This paper investigates the influence of sleeper spacing on the vibration and noise of railway tracks. Through numerical experiments of stationary harmonic loading problems for different sleeper distributions, the relationship between the variance of deviation in the sleeper location and the mean value and variance of the resonant amplitude is evaluated. The influence of randomness in the sleeper spacing on the frequency response is also examined. Moreover, since the track vibration is excited due to the interaction between the track and a running train, such problems are analyzed, taking into account the roughness between the railhead and the wheel tread. Based on a number of simulations, we assess the effect of the random and optimal sleeper distributions on the vibration and noise reductions.

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記述言語：日本語   出版者・発行元：土木学会  

まくらぎ配置がレールの振動およびそれに起因して発生する騒音に及ぼす影響について検討した.具体的には,レールの定点調和加振と走行車輪・軌道達成解析を通し,まくらぎ間隔の不均一性によるレール振動・放射音の低減効果を調べた.等間隔のまくらぎ配置の他に,実軌道におけるバラツキを設定した場合,および既往の研究で得られた最適なまくらぎ配置とした場合を対象として, lOOOHz以下の周波数域での応答にまくらぎ配置が及ぼす影響を検討した.The influence of sleeper arrangement on the rail vibration and the acoustic noise radiated from the rail is investigated. To this end, the stationary harmonic loading problem and the interaction between a moving wheel and a track are analyzed. As the sleeper arrangements, three cases of the regular spacing, stochastic distribution obtained by in-situ measurements and an optimal distribution are considered. Through these numerical experiments, the vibration and noise reductions by the introduction of the irregularity into the sleeper spacing are evaluated based on resonance modes at frequencies lower than lOOOHz.

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   出版者・発行元：Japan Society of Civil Engineers  

道床横抵抗力の非線形性がレール軸力-臨界速度関係の外乱鋭敏性に及ぼす影響について検討した．まず，軌道・半無限地盤連成系を対象に，道床横抵抗力の非線形特性を3次式で近似し，分散曲線に接する走行線より臨界速度を求めた．その結果，軸力-臨界速度関係はレールに作用する横圧の増加と共に低軸力側に移動することを確認した．また，地盤を剛基盤として求めた理論式より，この軸力低下が横圧の2/3乗に比例することがわかった．さらに，道床横抵抗力の非弾性履歴特性を考慮した定常応答解析を実施し，実際の軌道により近い条件下でも上述の鋭敏性が存在することを確認した．

DOI： 10.2208/jscejam.70.I_971

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Institute of Physics Publishing  

The time-domain boundary element method using the Haar wavelets is developed for reducing the computational cost of the BE wave propagation analysis. The Haar wavelets are used for the discretization of the boundary integral equation. The time variation of the unknown potential and flux is approximated using the conventional scheme. The small matrix entries of the coefficient matrix are truncated with the Beylkin-type matrix compression scheme at before and after calculation of double boundary integral. The present BEM has the numerical stability comparable to the piecewise constant Galerkin BEM. The sparsity of the coefficient matrix generated at an each time step rises as the time step proceeds
the memory requirement of the present method can be reduced in comparison with the conventional BEM. The reduction of the computational work from the conventional BE analysis is difficult because of the sparse system of the conventional time-domain BEM.

DOI： 10.1088/1757-899X/10/1/012222

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

This paper presents a level set-based topology optimization method for noise barriers formed from an assembly of scatterers. The scattering obstacles are modeled by elastic bodies arranged periodically along the wall. Due to the periodicity, the problem can be reduced to that in a unit cell. The interaction between the elastic scatterers and the acoustic field is described in the context of the level set analysis. The semi-infinite acoustic wave regions located on the both sides of the barrier are represented by impedance matrices. The objective function is defined by the energy transmission passing the barrier. The design sensitivity is evaluated analytically by the aid of adjoint equations. The dependency of the optimal profile on the stiffness of scatterers and on the target frequency band is examined. The feasibility of the developed optimization method is proved through numerical examples. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jsv.2013.05.027

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

This paper proposes a newly developed method, which measures absolute axial stress of continuous welded rails (CWR), based on the change of resonant frequency of standing wave mode of rails in the periodic infinite railway track structure. First, the authors theoretically derived dominant simultaneous equations regarding the vibration motions of a three-dimensional Timoshenko-beam under compressive or tensional axial-loadings. By applying the Floquet's theorem to dominant equations of the unit cell, which is an irreducible sub-structure with periodicity of the infinite track structure, the equations are simplified into Eigen-value problems in the frequency domain. Numerical dispersion analyses of wave modes propagating in a track made clear the relation among axial-loadings, wavenumber and natural frequency and provided an evaluation of the feasibility of the proposed method for the measurement of the absolute axial stress. Furthermore, in-situ measurements in the existing CWR track experimentally confirmed the linearity between the axial stress and the resonant frequency.

DOI： 10.2219/rtriqr.54.118

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   出版者・発行元：土木学会  

本研究では,バラスト材の弾塑性挙動をCyclic densificationモデルにより表現した有限要素法を用い,石川らが実施した実物大試験を対象として当該モデルの妥当性,および繰り返し荷重作用時のバラスト軌道の変形特性について考察する.また,より現実に近い荷重作用条件下での道床沈下解析を小さな計算負荷で表現するために, Cyclic densificationモデルを用いた3次元有限要素解析を行う場合を対象として,平面ひずみ近似の妥当性について検証する.平面ひずみ場は,軌道縦断方向,および軌道横断方向の2つの場合について考え, 2種類の平面ひずみ解析の適用可能性について, 3次元有限要素解析結果との比較を通して検討する.The finite element method(FEM) with the cyclic densification model is applied to the settlement analysis of the railway ballasted track subject to cyclic vertical loading. The railway ballast layer is modeled by 3-D or 2-D plane strain finite elements. The constitutive relation of the railway ballast is defined using the cyclic densification model. The model calibration is carried out in comparison with the cyclic loading test data on a full-scale ballasted track reported by Ishikawa et al. For the 3-D simulation, the load-displacement curve in loading process at the 1st cycle is comparable to one of the test results. The accumulated displacement at the top of the sleeper can be predicted with high accuracy; the simulated accumulation rate is higher than one of the test results. The 2-D plane strain FE analysis is attempted to reduce the computational cost for predicting the full-scale ballast settlement analysis. The plane strain approximation with respect to the longitudinal section of a track is valid to evaluate the stress, strain and displacement in the ballast layer.

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記述言語：日本語   出版者・発行元：土木学会  

レール支持部に存在する力学的非線形性が,レールの共振周波数と軸力との関係に及ぼす影響について考察した.そのために,まくらぎ位置を節とするレールの共振モードを対象に,調和加振下での定常解を与える汎関数をLagrangianの時間平均より求めた.当該汎関数より定常解や共振条件を導出し,共振周波数-軸力関係の加振力に対する鋭敏性を議論した.また,レール加振を模擬した数値解析を通し,本理論の妥当性を検証した.The influence of mechanical nonlinearity in rail supports on the resonant frequency-rail axial load relationship is investigated. To achieve this, a harmonic load exciting the pinned-pinned resonance mode is considered, and a functional which derives a steady-state solution is formulated by time average of the Lagrangian. In the theoretical study, the nonlinearity is introduced in the rotational stiffness at each sleeper support. Based on the variations of the functional, the sensitivity of the above relationship to the load amplitude is revealed. Furthermore, through numerical analyses, validity of the theory is proved.

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記述言語：日本語   出版者・発行元：土木学会  

A coupling method of FEM and wavelet BEM is developed for 2-D steady-state scalar wave equation. The wavelet BEM is formulated using the non-orthogonal spline wavelets. These wavelets have the vanishing moment property independent of the order of piesewise polynomials. The coefficient submatrices of the reduced equations on the wavelet-based BEM are also compressed with the truncation of small matrix entries. The linear algebraic equations with a sparse coefficient matrix are solved using iterative solver, e.g. Bi-CGStab, GPBi-CG and GMRES. In particular, the use of GMRES shows rapid and robust convergence in the present numerical experiments.

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記述言語：日本語   出版者・発行元：土木学会  

This paper presents a numerical method for two-dimensional solid phononic crystals having a defect. This problem is divided into two domains of the finite defective region and the surrounding periodic medium. The analysis method is then constructed by combining the finite element equation of the irregular region with the impedance matrix representing the external field. The impedance matrix is derived by analyzing a series of harmonic excitation problems of a periodic field given by the surrounding array. These solutions are obtained by the aid of Floquet transform. The developed method is applied to wave propagations through a defective field imbedded in a square lattice of circular holes. Modes trapped in the disturbed region are also analyzed for a composite material possessing a dispersion structure with a wide bandgap.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

This paper presents a numerical method for wave transmission through a periodic track having a disturbed region. The infinite track analysis is realized by attaching the transmitting boundaries at both ends of the finite sub-domain. To achieve this, an impedance matrix representing the transmitting boundary is constructed by utilizing eigenmodes for the transfer matrix of a unit cell. The developed method is applied to infinite tracks subjected to incident harmonic waves. Through numerical analyses, the influence of the stiffness of the pads on the wave transmission is examined. The relation between the transmittance and the band structure of track is also discussed.

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

This paper presents a numerical method for wave transmission through a periodic track having a disturbed region. The infinite track analysis is realized by attaching the transmitting boundaries at both ends of the finite sub-domain. To achieve this, an impedance matrix representing the transmitting boundary is constructed by utilizing eigenmodes for the transfer matrix of a unit cell. The developed method is applied to infinite tracks subjected to incident harmonic waves. Through numerical analyses, the influence of the stiffness of the pads on the wave transmission is examined. The relation between the transmittance and the band structure of track is also discussed.

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記述言語：日本語   出版者・発行元：土木学会  

本研究では, 回転硬化を考慮した拡張下負荷面モデルを用いた弾塑性連続体でバラスト道床をモデル化する場合を対象に, 大型繰り返し三軸試験結果から particle swarm optimization (PSO)アルゴリズムを用いて材料パラメータ値を同定した上で, 材料パラメータの変動がバラスト材の繰り返し変形解析結果に及ぼす影響について, 1次近似2次モーメント法(FOSM)を用いて評価した. 数値実験は石川らが実施した大型繰り返し三軸試験の応力条件と合致するように実施した. その結果, 解析の際の入力材料パラメータの変動が比較的小さい場合でも, 載荷・除荷第1サイクルのように, 残留ひずみの発生・蓄積量の大きい段階では, 入力の変動が解析結果では10倍程度に増幅される恐れがある. ただし, 第2サイクル以降, 残留ひずみの発生・蓄積のスピードが鈍った場合には, FOSMにより評価される残留ひずみの標準偏差は概ね一定値で推移する.In the cyclic deformation analysis of railway ballast with the extended subloading elastoplastic constitutive model, the influence of variation of the material parameters on the simulation results is investigated through numerical tests. The material parameters in the subloading surface model are idntified using the particle swarm optimization (PSO) algorithm and the cyclic triaxial test data presented by Ishikawa et al. The standard deviations of the simulated axial strain and volumetric strain are calculated with the first-order second-moment method (FOSM). Even when change of the input material parameter in the case of analysis is small, in the stage where generation and cumulation of permanent strain are large, the variation of the material parameters may be amplified by about 10 times by the variation of simulation results. In the stage where generation and cumulation of prmanent strain are small, the standard deviations of the siulations results calculated with FOSM are almost constant.

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本計算数理工学会  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

In the time-domain BEM with Haar wavelets for 2-D diffusion problems, the relation between the number of non-zero entries of the coefficient matrices and the degree of freedom (DOF) N is theoretically investigated using the information on the size and the arrangement of the support of the basis functions. The coefficient matrices are compressed using the Beylkin-type level-independent truncation scheme with a DOF-independent prescribed threshold value. The number of non-zero entries of the matrix G(L,p) and H(L,p) (1 ≤ p ≤ L, L: current time step), N(G(L,p)) and N(H(L,p)), increases in proportion to the factors log N, N1/2, N and N log N, except for the behavior in the smaller DOF range where N(G(L,p)) and N(H(L,p))∼O(N2). For M»1 and N»1, N(G(L,p)) and N(H(L,p)) show O(N log N) in matrix compression with a prescribed threshold value λ.

DOI： 10.2208/jscejam.67.I_95

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

This paper presents a numerical method for surface elastic waves in a half-space possessing a two-dimensional periodicity. The solution is expressed by plane waves in the vertical direction, while it is approximated by finite elements in the horizontal plane. By virtue of the Bloch's theorem, the problem is reduced to equations of motion in a unit cell. The vertical wavenumbers satisfying the equations in the unit cell are determined by solving an eigenvalue problem with respect to the wavenumbers. As numerical examples, periodic arrays of piles embedded in a ground are analyzed. In the analyses piles made of concrete and a soft material are considered with arrangements given by the square and the triangular honeycomb lattices. Under these conditions, the influences of the stiffness and the lattice pattern of piles on the band structure are investigated.

DOI： 10.2208/jscejam.67.I_905

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

This paper presents a BE-based shape optimization method for acoustic problems in the context of shape design of sound insulating walls. In order to avoid the convergence to a local minimal solution around an initial shape, the topological derivative is introduced. Based on the global distribution of the topological derivative, new shape or topology are attained by nucleating small scattering bodies. Evaluation of the topological derivative is achieved within the framework of the boundary element analysis. To cope with the topological change due to the nucleation and cutting of thin branches, shape is updated by the aid of the level set approach during the optimization process. Through numerical examples, it is proved that the developed method can find a shape with good performance irrespective of its initial shape. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.enganabound.2010.06.017

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   出版者・発行元：日本工学教育協会  

A learn-by-doing engineering career education program adopted by MEXT of Japanese Government has been conducted for three years with the assistance of named “A network of 100 wise men” , which is a novel supporting organization for the students and faculties of Niigata University. The network is composed by the company engineers or social technicians who have rich experiences in the careers of the actual R&D processes. We have confirmed that the practical experiences they possessed on the course of their R&D processed are quite effective for the students to give them the practical engineering education.

DOI： 10.4307/jsee.58.5_67

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

レールが軸力を受けている無限軌道を対象に波動分散解析を行った. 解析では, レールとまくらぎを3次元Timoshenkoはり要素により離散化し, 水平・鉛直たわみと振り振動の影響を再現した. まくらぎ1区間で与えられる軌きょう1ユニットの運動方程式にFloquet原理を適用し, 無限軌道内を伝播する波動モードの分散特性を求めた. 解析結果に基づき, 軸力に鋭敏な振動モードや, 締結装置の剛性などが共振周波数に及ぼす影響などについて考察した.Wave modes propagating in rails subjected to an axial load due to temperature stress are analyzed. An infinite track consisting of rails and sleepers is modeled by 3-D Timoshenko beams. The Floquet theorem is applied to the equation of motion of track sub-structure given by a repetitive unit. The wave dispersion analysis is then reduced to an eigenvalue problem in terms of the axial load, the wave number and the frequency. Sensitivity of axial loads to the wave number and frequency is investigated in the context of the dispersion analysis. Through those analyses, modes which are suitable for evaluation of axial load and the influence of uncertainties in track modeling on these modes are discussed.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

This paper presents a numerical method to construct transmitting boundaries for periodically supported railway tracks. This is realized by the derivation of impedance matrix for a half-infinite track. To achieve this, dynamic response of the infinite track corresponding to the half-infinite model is analyzed for a series of harmonic loading modes. The infinite problems are solved by virtue of Floquet transform. The developed method is applied to a periodically supported rail having a finite irregular zone subjected to harmonic loads. It is reduced to a dynamic problem of a finite track with the transmitting boundaries attached on both ends. Through comparison with the present method and a conventional way using a very long but finite railway model, the superiority over the truncated model is demonstrated.

DOI： 10.1299/jmtl.3.44

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

This paper describes the development of prediction method for ground-borne vibration from railway tunnels. Field measurement was carried out both in a subway shield tunnel, in the ground and on the ground surface. The generated vibration in the tunnel was calculated by means of the train/track/tunnel interaction model and was compared with the measurement results. On the other hand, wave propagation in the ground was calculated utilizing the empirical model, which was proposed based on the relationship between frequency and material damping coefficient <I>α</I> in order to predict the attenuation in the ground in consideration of frequency characteristics. Numerical calculation using 2-dimensinal FE analysis was also carried out in this research. The comparison between calculated and measured results shows that the prediction method including the model for train/track/tunnel interaction and that for wave propagation is applicable to the prediction of train-induced vibration propagated from railway tunnel.

DOI： 10.1299/jmtl.3.53

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IOP PUBLISHING LTD  

The time-domain boundary element method using the Haar wavelets is developed for reducing the computational cost of the BE wave propagation analysis. The Haar wavelets are used for the discretization of the boundary integral equation. The time variation of the unknown potential and flux is approximated using the conventional scheme. The small matrix entries of the coefficient matrix are truncated with the Beylkin-type matrix compression scheme at before and after calculation of double boundary integral. The present BEM has the numerical stability comparable to the piecewise constant Galerkin BEM. The sparsity of the coefficient matrix generated at an each time step rises as the time step proceeds; the memory requirement of the present method can be reduced in comparison with the conventional BEM. The reduction of the computational work from the conventional BE analysis is difficult because of the sparse system of the conventional time-domain BEM.

DOI： 10.1088/1757-899X/10/1/012222

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   出版者・発行元：日本工学教育協会  

We report the results and further problems on what we call the learn-by-doing engineering career education program which has been conducted for three years by the grant-in-aid adapted in 2006 by MEXT of Japanese government. In the paper, we attempt to estimate the processes of the internship programs which were supported by &ldquo;A Network of 100 Wisdom&rdquo; , an organization outside the university. In this year, we have accomplished the construction of three kinds of internship programs, which have been combined one after another. We confirm that we have given the university students strong motivations toward the technical studies through these practical internship programs.

DOI： 10.4307/jsee.57.5_73

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：The Japan Society of Mechanical Engineers  

This paper presents a numerical method to construct transmitting boundaries for periodically supported railway tracks. This is realized by the derivation of impedance matrix for a half-infinite track. To achieve this, dynamic response of the infinite track corresponding to the half-infinite model is analyzed for a series of harmonic loading modes. The infinite problems are solved by virtue of Floquet transform. The developed method is applied to a periodically supported rail having a finite irregular zone subjected to harmonic loads. It is reduced to a dynamic problem of a finite track with the transmitting boundaries attached on both ends. Through comparison with the present method and a conventional way using a very long but finite railway model, the superiority over the truncated model is demonstrated.

DOI： 10.1299/jmtl.3.44

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：The Japan Society of Mechanical Engineers  

This paper describes the development of prediction method for ground-borne vibration from railway tunnels. Field measurement was carried out both in a subway shield tunnel, in the ground and on the ground surface. The generated vibration in the tunnel was calculated by means of the train/track/tunnel interaction model and was compared with the measurement results. On the other hand, wave propagation in the ground was calculated utilizing the empirical model, which was proposed based on the relationship between frequency and material damping coefficient <I>α</I> in order to predict the attenuation in the ground in consideration of frequency characteristics. Numerical calculation using 2-dimensinal FE analysis was also carried out in this research. The comparison between calculated and measured results shows that the prediction method including the model for train/track/tunnel interaction and that for wave propagation is applicable to the prediction of train-induced vibration propagated from railway tunnel.

DOI： 10.1299/jmtl.3.53

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   出版者・発行元：一般社団法人 日本機械学会  

The education centre for engineering and technology was established in the faculty of engineering at Niigata University in spring 2005 so as to elevate the motivation of undergraduate students for learning through making some products. To this end, we have been practicing several new engineering education programs, such as multidisciplinary projects similar to PBL, the active involvement of the students with the collaborative research and development between university and private companies and so on. These attempts are designed for the students to have fundamental or compulsory competence for engineering. In this report, current features of these programs are mentioned, and critical issues as well as future direction of engineering education are discussed.

DOI： 10.1299/jsmetsd.2009.29

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

DOI： 10.2208/journalam.11.1031

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2208/journalam.11.149

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

高架橋に沿って伝播する波動モードを数値解析により調べた. 当該構造物は無限周期構造により理想化し, はりモデルで離散化した. 減衰せず無限遠まで伝播して行く波動モードの解析において, Floquet原理を適用することで具体的解法を構成した.この場合,無限周期系における波動問題は, 周期構造を構成している最小単位(ユニットセル)の離散化により解析可能となる. 具体例を対象に伝播モードの分散曲線を求め, 発生し得るモードの種類とバンド特性について調べた.Wave propagation is analyzed for a periodic viaduct. By virtue of the Floquet's principle the dynamic problem can be reduced to the one in a unit cell representing the periodicity. This formulation leads to an eigenvalue problem associated with the Floquet wave number (propagation constant) and the circular frequency. The group velocity dispersion curves are drawn by solving the eigenfrequencies with scanning the wave number interval. It is found that the propagation modes can be classified into two groups. One is characterized by the deflection of girder. The other is dominated by the bending of columns. The influences of numerical modeling on the dynamic properties are also investigated.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11532/structcivil.54A.114

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

Wave propagation in an infinite periodic railway track is investigated. In the analysis the constituents of a rail and sleepers are considered for the track model. Propagation modes of the periodic structure are described by virtue of the Floquet transform. This method makes it possible to reduce the infinite periodic problem to an eigenvalue problem for a unit structure with finite length. The rail is modeled by a Timoshenko beam and discretized by finite elements. Through numerical analysis the wave number-frequency curves for the propagation modes are obtained. It is found that the installation of sleepers causes a mode in which the propagation waves are accompanied by sleeper vibration. Besides, the influence of the stiffness of rubber pads on the propagation modes is discussed.

DOI： 10.2208/journalam.10.1029

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

回転硬化を考慮した下負荷面モデルを用いて, 道床部に使用されるバラスト材の繰り返し変形挙動の弾塑性解析を試みた. 繰り返し初期における載荷・除荷時のつり合い経路は解析と実験とで概ね一致させることが可能である. それ以降の繰り返し時においては, 変形係数は解析結果と実験結果とで概ね同程度であるが, 残留軸ひずみの累積速さが一致をみておらず, 繰り返し100回程度～1500回程度においては, 残留軸ひずみの値に明瞭な差が認められた. 1500回目程度以降の漸進的なひずみの累積過程においては, 解析によって良好に再現できた. 一方, 繰り返し載荷時の体積変化については, 解析によって収縮・膨張の定性的な傾向を再現するにとどまった.Cyclic elastoplastic behaviour of railway ballast is simulated using the subloading surface model with rotational hardening, in order to employ in the continuum-type settelement simulation model. In low (under 100 load cycles) and high cycle range (over 1500 load cycles), the simulation results on the deviatoric stress - strain relation and the magnitude of permanent strain is good agreement with the triaxial test results. The prediction of the volumeric strain appears to be somewhat inaccurate, though change from compaction to dilatation during cyclic loading can be simulated.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：土木学会  

地盤振動低減を目的に, 地下鉄トンネル覆工厚の最適化を試みた. その際に, 本来覆工厚と連動して変化するトンネル曲げ剛性と質量とを分離して評価する方法を構成した. その下で設計感度解析を実施し, 剛性と質量のいずれか一方, または両者について最適化した場合の覆工厚分布を求めた. その結果, 振動低減に対する剛性と質量の寄与度は, 振動数により異なることがわかった. また, トンネル上半分(アーチ部)および底部(インパート部)の覆工厚を増すことが, 振動低減につながることが確かめられた.An optimization method is developed for the tunnel thickness design in the context of the vibration reduction of subway. The split of effects into stiffness and mass is attempted in the design sensitivity analysis. To achieve this, the elastic modulus and mass density are described in terms of the tunnel thickness. The stiffness and mass matrices can then be given by functions of the thickness. Through optimization analysis, it is found that the contribution of the stiffness and mass to the vibration reduction depends on the frequency. Moreover, it can be concluded that the thickening of the upper part and bottom of tunnel leads to the reduction of radiated waves.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JOHN WILEY & SONS LTD  

A boundary element method is developed for the topology optimization problem. The topological change is captured using the level set method. The level set function which is defined by signed distance from the boundary contour is assigned to fixed grid points. Boundary elements are developed along the zero contour of the level set function. The design sensitivity analysis is performed for the boundary element equation, and then the boundary velocity is obtained. The velocity field which leads the level set function to optimal material distribution is obtained by the extension of the boundary velocity. Numerical examples show that the proposed method is valid for the topology optimization problems. Copyright (c) 2006 John Wiley & Sons, Ltd.

DOI： 10.1002/cnm.919

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.2208/journalam.9.353

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   出版者・発行元：土木学会  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Topology optimization methods with continuous design variables obtained by the homogenization formula or the solid isotropic microstructure with penalty (SIMP) model are widely used in the layout of structures. In the implementation of these approaches, one must take into account several issues, e.g., irregularity of the problem, occurrence of the checkerboard pattern, and intermediate density. To suppress these phenomena, the employment of additional strategies such as the perimeter control or the filtering method will be required. In this paper, a topology optimization method which can eliminate these difficulties is developed based on the volume of fluid (VOF) method. In the method, shape design is described in terms of the VOF function. Since this function is defined by a volume fraction of material occupying each element, it can be recognized as a continuous material density in the SIMP model. Within the framework of the VOF analysis, the topology optimization procedure is reduced to a convection motion of the material density governed by a Hamilton-Jacobi equation as in the level set method. Through numerical examples, the validity of the proposed method is investigated.

DOI： 10.1007/s00158-005-0582-5

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.2208/journalam.8.1037

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We measured factors relating to track dynamic behaviour, such as dynamic wheel loads and rail seat forces near a rail joint induced by running vehicles. We also proposed a track dynamic model to consider the excitation by wheels passing over discontinuous fish plate rail joints. We then compared the measured and analytical results, and found a close agreement between them. We also proposed a prediction model of ballast settlement near rail joints and calculated the effects of countermeasures against joint dips on ballast settlement.

DOI： 10.2219/rtriqr.46.124

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present paper, we investigate theoretically and experimentally the number of non-zero matrix entries generated by the wavelet BEM with the Beylkin-type compression algorithm. The Beylkin-type algorithm, which is based on a prescribed level-independent threshold, retains the asymptotic convergence rate of BE solutions, like widely-used level-dependent compression schemes. The coefficient matrix compressed by the Beylkin-type scheme has O(N 1+γ) (0 &lt
γ &lt
1, N: degree of freedom (DOF)) non-zero entries
level-dependent schemes enable us to reduce the matrix entries up to O(N(log N)α) (α ≥ 1). However, for matrix compression using the Beylkin-type scheme the compression rate is greater than or comparable to that of the Schneider's level-dependent scheme, in the moderate DOF range.

DOI： 10.2208/jsceseee.22.219s

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.2208/journalam.7.1313

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WIT PRESS  

The influence of the truncation schemes for wavelet BEM on the compression rates of the coefficient matrices is investigated through the asymptotic estimation and numerical experiments. In the present paper the truncation schemes given by either Schneider's level-dependent scheme or the Beylkin-type algorithm are considered. The theoretical estimation of the number of stored entries shows O(N1+a) (0 &lt; alpha &lt; 1) for the Beylkin-type compression and O(N(log N)(beta)) (beta &gt; 1) for the level-dependent truncation. However, in actual BE analysis the Beylkin-type algorithm enables us to compress the coefficient matrix at the rates comparable to those for Schneider's scheme.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WIT PRESS  

An identification method is developed for unknown material parameters in a dynamic subway-track model. The proposed method is formulated in the framework of genetic algorithms (GAs). An individual in the GA is defined by a set of real unknown parameters not by a coded string. The evaluation of fitness is carried out based on a three-dimensional dynamic analysis, in which the subway track, tunnel and ground are modeled by means of the coupling of boundary element (BE) and finite element (FE) methods. To save the computational work, a neural network (NN) in which the material parameters are input data and the spectrum ratios are output data is introduced. The developed method is validated through application to numerical models and in situ measurements.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

A Timoshenko beam finite element suitable for vehicle-track vibration analysis is proposed and is applied to a jointed railway track. In several simulation models, the track vibration excited by a train running on the rail is formulated as a dynamic problem where a sequence of concentrated loads moves on the discretely supported Timoshenko beam. The external force is then defined by the concentrated load. The Timoshenko beam subjected to concentrated loads deforms with the slope discontinuity at the loading points. This deformation cannot be represented by the usual finite elements, which causes the fictitious responses of the beam. The present finite element model removes the undesirable response by completely modelling the slope discontinuity. This is achieved by the TIM7 element with the piecewise-linear hat functions. The jointed track model constructed by this finite element is employed to predict the impulsive wheel-track contact force excited by the wheel passage on rail joints. The rail joints with fishplates are of great concern to track deterioration, the settlement of ballast track and the failure of track components. In the present paper the effects of train speed and gap size of the joints on the impact force are assessed from simulation results. © IMeohE 2004.

DOI： 10.1243/0954409041319687

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.2208/journalam.6.301

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

A practical strategy is developed to determine the optimal threshold parameter for wavelet-based boundary element (BE) analysis. The optimal parameter is determined so that the amount of storage (and computational work) is minimized without reducing the accuracy of the BE solution. In the present study, the Beylkin-type truncation scheme is used in the matrix assembly. To avoid unnecessary integration concerning the truncated entries of a coefficient matrix, a priori estimation of the matrix entries is introduced and thus the truncated entries are determined twice: before and after matrix assembly. The optimal threshold parameter is set based on the equilibrium of the truncation and discretization errors. These errors are estimated in the residual sense. For Laplace problems the discretization error is, in particular, indicated with the potential's contribution ∥c∥ to the residual norm ∥R∥ used in error estimation for mesh adaptation. Since the normalized residual norm ∥c∥/∥u∥ (u: the potential components of BE solution) cannot be computed without main BE analysis, the discretization error is estimated by the approximate expression constructed through subsidiary BE calculation with smaller degree of freedom (DOF). The matrix compression using the proposed optimal threshold parameter enables us to generate a sparse matrix with O(N1+γ) (O≤γ &lt
1) non-zero entries. Although the quasi-optimal memory requirements and complexity are not attained, the compression rate of a few per cent can be achieved for N ∼ 1000. © 2003 John Wiley and Sons, Ltd.

DOI： 10.1002/nme.666

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

A wavelet BEM is applied to the evaluation of the effective elastic moduli of unidirectional composites, based on the homogenization theory. This attempt is devoted to the reduction of computational cost for the BE-based homogenization analysis. Truncation for matrix compression is carried out by the Beylkin-type algorithm. A thresholding value for the truncation is set such that the discretization error of BE solution is comparable to its truncation error. Besides, rearrangement of the BE equations is proposed to attain rapid convergence of iterative solutions. Through investigation of asymptotical convergence of the effective moduli, it is found that the BE-based homogenization analysis ensures the same rate of convergence for effective moduli as for characteristic functions. By applying the wavelet BEM to heterogeneous media which have microstructures with many voids, the effective moduli with agreement of 2-4 digits can be evaluated using 20-50% memory requirements of conventional BE approaches. (C) 2003 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0955-7997(02)00154-6

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）   出版者・発行元：土木学会  

DOI： 10.2208/journalam.5.101

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）   出版者・発行元：土木学会  

A wavelet-weighted Gauss quadrature formula is developed to reduce computational work in wavelet BEM. The non-orthogonal wavelet constructed by the authors is used as the basis. This wavelet is defined as a spline, which requires us to divide an interval into several subintervals in calculation of integrals corresponding to the basis. Besides, the number of the subintervals increases in propotion to the order of vanishing moments. The computational work for generating matrices thus is expensive, in particular, in application of numerical integration. The present formula enables us to carry out numerical integrations without division of the interval, since the wavelet is also employed as a weighting function of the formula. The number of integration points is determined a priori based on estimation of the integration error and a prescribed accuracy. In wavelet BEM, the error tolerance can be given by a threshold for matrix compression. Through numerical experiments, availability of the present method is verified.

DOI： 10.2208/journalam.4.127

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その他リンク： http://hdl.handle.net/10191/4880

記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Application of Haar wavelet to h-hierarchical adaptive method is attempted to improve the performance. The wavelet boundary element method (BEM) is developed by means of the Galerkin method. In order to save memory requirement and computation time, sparse matrices are obtained by truncation of matrix coefficients. Error indicator and estimator are constructed based on the difference between the true solution and its projection onto the mesh. These values are effectively evaluated using the boundary element solution. The adaptive method is developed for 2D Laplace problems. Through numerical examples, performance of the present method is investigated concerning the sparseness of matrices and the computation time devoted to calculation of matrix coefficients and to equation solving process. © 2001 Elsevier Science Ltd.

DOI： 10.1016/S0955-7997(01)00015-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Non-orthogonal spline wavelets are developed for Galerkin boundary element method. The proposed wavelets have compact supports and closed-form expressions. Besides, one can choose arbitrarily the order of vanishing moments of the wavelets independently of order of B-splines. Sparse coefficient matrices are obtained by truncating the small elements a priori. The memory requirement and computational time can be controled by changing the order of vanishing moments of the wavelets. As an iterative technique for solving the boundary element equations, GMRES(m) method is employed. Diagonal scaling and incomplete LU factorization (ILU(0)) are considered for the preconditioning. The ILU(0) becomes an effective preconditioner for higher order vanishing moments. Through numerical examples, availability of the proposed wavelets is investigated. © 2001 Elsevier Science Ltd.

DOI： 10.1016/S0955-7997(01)00036-4

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WIT PRESS  

A Gauss quadrature method in which the wavelet is used as a weighting function is developed for wavelet BEM. Non-orthogonal spline wavelets that can change the order of vanishing moments as well as the order of polynomial are considered in BE analysis. Although the increase in the order of vanishing moments leads to the increase in the sparseness of matrices, that also increases the number of intervals in which the wavelet is described by a certain polynomial. The proposed quadrature method does not need to divide the support of wavelets in the calculation of matrix coefficients, while the Gauss-Legendre formula obliges us to divide the support into several intervals. Consequently the proposed method allows to reduce the computational work for generation of matrices. Estimation of the error in the numerical integration is also attempted in order to decide the number of integral points for a specified tolerance. Numerical experiments axe carried out, and the feasibility of the proposed method is examined.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WIT PRESS  

This paper presents a practical determination method for optimal threshold in wavelet BEM. The optimal threshold, used for truncation of coefficient matrix entries, is determined such that truncation error is comparable to discretization error, in order to minimize the computational cost without deterioration of the accuracy. Errors are estimated in the residual sense. The discretization error is estimated based on the asymptotical behaviour of the residual R. These enable us to determine the optimal threshold in advance, independently of prescribed analytical conditions. Through numerical example, availability and validity of the proposed strategy axe investigated.

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）   出版者・発行元：Japan Society of Civil Engineers  

The steel pipe attachment method has been employed as a seismic strengthening technique for RC columns in cut and cover tunnels. In this method, two concrete-filled tubular steel columns are attached to the RC column from both sides, and they will prevent the, tunnel from collapse even if the RC columns undergo shearing failure. In order to appreciate the mechanical properties of the attached column, numerical analyses are accomplished. This paper presents the modeling of the RC and attached columns and then constructs an interaction analysis method. Several discussions are carried out through comparison between the numerical and the experimental results.

DOI： 10.11532/journalte1991.10.87

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）   出版者・発行元：土木学会  

DOI： 10.2208/journalam.3.157

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）   出版者・発行元：土木学会  

DOI： 10.2208/journalam.3.107

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 土木学会  

鋼製組立網に用いられる金網の弾塑性解析手法を構成した. 面内変形を対象に, 金網を力学的に等価な二次元連続体によりモデル化した. 構成式は, 金網を構成するユニットセルの頂点における列線作用力の変位微係数を含むかたちで与えられる. 有限要素解析での剛性方程式の作成において, 列線作用力を応力評価点毎に効率よく求めるため, ニューラルネットワークを導入し, その学習結果に基づき任意変形下での列線作用力の評価を行った. 金網の引張り試験との比較を通し, 本手法の妥当性を確認した.

DOI： 10.2208/jscej.1999.633_205

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.2208/journalam.2.153

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WIT PRESS  

An h-hierarchical method is developed using Haar wavelets for two-dimensional Laplace problems and performance of the developed method is investigated. Haar wavelets provide complete hierarchical system for approximate solution and sparse coefficient matrix by truncation. The preconditioned GMRES(m), a kind of iterative solvers, is employed to solve equations. Through numerical example, it is found that the memory requirement is decreased, however, the CPU time is not shortened because of a large cost of preconditioning.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 土木学会  

地下鉄の軌道に用いられる防振まくらぎなどの低バネ係数軌道の振動特性を数値解析により予測・把握することを目的に, 台車・軌道系の非線形振動を直接モデル化し得る解析手法の構成を試みた. 具体的方法は, 走行荷重下でのレールの振動系と質点系でモデル化した車輪やまくらぎの振動系を時間域積分表現式で定式化を行い, 振動系の数値解の安定性と精度とを向上させるため, 質点系とレールとの間に作用する接触力を時間域で離散化した. さらに, 各系における接触力が適合するように質点系の時間積分スキームを積分方程式に基づき構成しか. 解析例として, 防振まくらぎ軌道の軌道パッドと防振パッドのバネを線形とした場合と, 圧縮変形試験から得られた非線形特性を反映させた場合での解析を行い, 軌道各部の振動の差違について比較検討した.

DOI： 10.2208/jscej.1998.61

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：COMPUTATIONAL MECHANICS PUBLICATIONS LTD  

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記述言語：日本語   出版者・発行元：土木学会  

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記述言語：日本語 著書種別：事典・辞書

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

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記述言語：日本語   出版者・発行元：日本計算数理工学会  

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記述言語：日本語   出版者・発行元：新潟大学災害・復興科学研究所  

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記述言語：日本語   出版者・発行元：公益社団法人日本工学教育協会  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

In this study, we theoretically investigate the optimized sleeper spacing which can suppress resonances. We introduced a minimization problem in which the objective function is given by the wave transmittance and the design variable is defined by sleeper distribution. In the analysis the rail is modeled by a Timoshenko beam and the sleeper is represented by a mass. The infinite track analysis is realized by attaching the transmitting boundaries at both ends of the finite optimization region. Through numerical analyses the sleeper spacing effective in reduction of the transmittance is defined. Furthermore, the feasibility of the proposed method is validated through response analyses for a harmonic load.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

The 3-D deformation behaviour of the full-scale ballasted track is simulated using the finite element method (FEM) with the cyclic densification model. The present constitutive model, proposed by Suiker et al, is based on the overstress formulation like Perzyna's viscoplastic model. The simulated vertical displacement is good agreement with the test results on the full-scale cyclic vertical loading tests. The permanent strain below sleepers is accumulated by volumetric compaction in the range under 300 loading cycles. The accumulated permanent strain in the range over 300 cycles is caused by the frictional sliding.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

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記述言語：日本語   出版者・発行元：新潟大学工学部  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

In the time-domain BEM with Haar wavelets for 2-D diffusion problems, the relation between the number of non-zero entries of the coefficient matrices and the degree of freedom(DOF) N is theoretically investigated using the information on the size and the arrangement of the support of the basis functions. The coefficient matrices are compressed using the Beylkin-type level-independent truncation scheme with a DOF-independent prescribed threshold value A. The number of non-zero entries of the matrix G^<(L,p)> and H^<(L,p)> (1 &le; p &le; L, L: current time step), N(G^<(L,p)>) and N(H^<(L,p)>), increases in proportion to the factors log N, N^<1/2>, N and N log N, except for the behavior in the smaller DOF range where N(G^<(L,p)>) and N^(H<(L,p)>) 〜 O(N^2).

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

This paper presents a wave propagation analysis method for a periodic railway track having a finite irregular zone. A half-infinite periodic sub-region is represented by an impedance matrix. The infinite system is reduced to a matrix equation with finite DOF by coupling the impedance matrices with the irregular zone. Through numerical examples, influence of the heterogeneity on the wave propagation is discussed in terms of the dispersion of wave modes. It is found that the irregularity is effective to cut off the wave transmission.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

The 3-D finite element analysis for cyclic vertical loading tests of a full-scale railway ballasted track is implemented using the extended subloading surface elastoplastic model with the modified material functions proposed by Hashiguchi. The modified function fulfills the convexity of the yield surface for a whole range of the friction angle. The vertical displacement of the bottom of the sleeper is good agreement to the experiment data under the prescribed cyclic loading. The large plastic strain extends from the edge of the sleeper to the bottom of the ballast layer; the frictional sliding zone can be found in the ballast layer.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

The numerical algorithm for reducing the computational work of the cyclic deformation analysis using the hypoplastic model with the time-domain homogenization is proposed. The multiple temporal scales of the stress, strain and void ratio are introduced, and the original constitutive equations are decomposed into coupled micro-chronological and macro-chronological equations using asymptotic analysis. The proposed algorithm enables us to change the step width of the macro-chronological analysis, and to reduce the number of the micro-chronological analysis. The accuracy of the simulation results depends on convergence speed of the accumulation of the permanent deformation.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

The localization in the buckling of infinite rail due to temperature stress is studied. A tangent rail is modeled by a straight Bernoulli-Euler beam cramped by sleepers. The buckling load is derived theoretically for each wavenumber. The bifurcation path is also analyzed under periodic deformation. On that path, instability analysis is achieved for deformation rates with wavenumbers around the buckling point. From these results, a bifurcation set embedded in the space spanned by wavenumber, amplitude and temperature is developed. It is found that deformation modes corresponding to the all wavenumbers in the neighborhood of buckling point contribute to the growth of the localization in the rail deflection.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

The cyclic deformation of railway ballast is simulated using the cycle-jump type constitutive model. The cycle-jump type model is based on the overstress formulation. The reversible response is represented by a pressure-dependent, hypoelastic model. The criterion of generation of progressive plastic deformation, the shakedown stress, is assumed to depend the accumulative plastic strain. The present model is used to simulate the cyclic triaxial tests of railway ballast. The accuracy of the simulation results depends on the convergence of the strain accumulation, while the larger value of the cycle increment ΔN enables us to reduce the computational work.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

The wavelets are applied to the time-domain boundary element method for solving the 2-D scalar wave equation. In the present method, the wavelets are used for approximating the unknowns on boundary, and for Galerkin discretization. Most of the coefficient matrix entries are small due to the vanishing moment property of the wavelets. The truncation of the small entries contributes to generate the sparse coefficient matrices. The use of wavelets, in particular, enables us to reduce the number of the matrix entries required to calculation of time convolution. However, the threshold for the truncation should be determined in consideration of the accuracy of the approximate solutions.

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記述言語：英語   出版者・発行元：一般社団法人日本機械学会  

The 3-D simulation of cyclic vertical loading tests of a full-scale railway ballasted track is attempted using the finite element method (FEM). The ballast layer is modeled as the continuum body of which the elastoplastic behavior is described by the subloading surface model with rotational hardening. The variation tendency in the relation between the vertical displacement of the bottom of the sleeper and the vertical load can be simulated using the present FE model. The simulated permanent displacement is comparable to those of test results. The large plastic strain extends from the edge of the sleeper to the bottom of the ballast layer; the frictional sliding zone can be found in the ballast layer.

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：一般社団法人 日本機械学会  

DOI： 10.1299/jsmehs.2009.46.153

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記述言語：日本語   出版者・発行元：公益社団法人 日本工学教育協会  

DOI： 10.20549/jseejaarc.2009.0_142

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

The 3D ascending behavior of migratory fish is modeled using the individual-based model and an agent-type movement decision scheme. The perceived stimuli strength of migratory fish are estimated with four physical variables: velocity, strain, pressure and light intensity. The fish movement at each time step is selected from among the prescribed five movement paterns. Qaulitative validity of the simulation results on the ascending behavior is verified through numerical examples.

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：公益社団法人 日本工学教育協会  

DOI： 10.20549/jseejaarc.2008.0_460

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記述言語：日本語   出版者・発行元：公益社団法人 日本工学教育協会  

DOI： 10.20549/jseejaarc.2008.0_434

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記述言語：日本語   出版者・発行元：公益社団法人 日本工学教育協会  

DOI： 10.20549/jseejaarc.2008.0_436

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：公益社団法人 日本工学教育協会  

DOI： 10.20549/jseejaarc.2007.0_754

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記述言語：日本語   出版者・発行元：新潟大学  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

A Timoshenko beam finite element suitable for vehicle/track vibration analysis is proposed. In the present analysis the Timoshenko beam is introduced to model a rail. Since the rail is usually subjected to several moving and stationary concentrated loads, the slope deflection of the Timoshenko beam has discontinuity at the acting points of these concentrated loads. Hence, the use of the finite element (FE) incompatible with the slope discontinuity causes fictitious responses. In this paper the FE which is compatible with the deflection of Timoshenko beam subjected to concentrated loads is developed using the TIM7 element and the pyramid-shape function. Numerical results show that the proposed FE can remove the non-physical response.

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記述言語：日本語   出版者・発行元：一般社団法人日本機械学会  

A Timoshenko beam finite element suitable for vehicle/track vibration analysis is proposed. In the present analysis the Timoshenko beam is introduced to model a rail. Since the rail is usually subjected to several moving and stationary concentrated loads, the slope deflection of the Timoshenko beam has discontinuity at the acting points of these concentrated loads. Hence, the use of the finite element (FE) incompatible with the slope discontinuity causes fictitious responses. In this paper the FE which is compatible with the deflection of Timoshenko beam subjected to concentrated loads is developed using the TIM7 element and the pyramid-shape function. Numerical results show that the proposed FE can remove the non-physical response.

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   出版者・発行元：日本計算工学会  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国

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受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国

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