〔Major achievements〕Approximated Solutions of Optimal Angle in Extended Projection Model of a Point Mass
Kazuhiro Tsuboi; Takahiro Hoshino, Lead, The Japan Society for Industrial and Applied Mathematics (JSIAM)
Transactions of the Japan Society for Industrial and Applied Mathematics, 25 Sep. 2023, [Reviewed]

〔Major achievements〕Reappearance of change in time of rotation axis with simulation in baseball-type acceleration sensor
Rio HIYAMA; Hiroyuki NAGAOKA; Kazuhiro TSUBOI; Shigeho NODA and Ryutaro HIMENO, Corresponding, 硬式野球ボール型加速度センサを用いた飛翔実験の結果から示唆された飛翔時に発生する回転軸の変化について考察した．センサユニット内の各センサが剛体的に配置された場合の各センサ位置での回転による加速度を定式化することでセンサ出力のシミュレータを作成した．ストレートとカーブの2球種に対して，センサ出力から得られた回転軸が時間的に変化する条件と回転軸をその初期値に固定して向きが変化しない条件でシミュレーションを行い，飛翔実験で得られたセンサ出力と比較した．その結果，前者の条件によってセンサから出力された加速度データが再現されることを確認し，ボール型センサの回転軸が飛翔時に変化することを示した．, 日本機械学会
Transactions of the JSME (in Japanese), 25 Jul. 2021, [Reviewed]

Reconsideration on projection angle of point mass
Kazuhiro Tsuboi, The Pysical Society of Japan
大学の物理教育, 15 Mar. 2019, [Reviewed], [Invited]

Rotational Property of a Ball in Flight by using Built-in Acceleration Sensors
NAGAOKA Hiroyuki; HIYAMA Rio; TSUBOI Kazuhiro; NODA Shigeho; HIMENO Ryutaro,

Direct measurement of the rotational characteristics in flight of a baseball-like ball is performed by using a built-in acceleration sensor unit. This sensor unit consists of one three-axis sensor for low acceleration and three sensors for high acceleration. In the preliminary experiment, we determine the moment of inertia of the ball set up the sensor unit and it has different values in each rotation axis. At the same time, the accuracy of sensor outputs is confirmed. In order to investigate the variation of the rotation axis of the ball in flight, sensor outputs are simulated. As the result, measured outputs are reproduced successfully in the case of giving the time variation of the rotation axis obtained in the flight experiment, while the outputs are rather different under the condition of the fixed rotation axis. Furthermore, we study the temporal behavior of the translational acceleration of the ball and clarify the periodic variation of the direction of this acceleration component. These results suggest that the rotation axis of balls is varying in flight.

, The Japan Society of Mechanical Engineers
The Proceedings of the Symposium on sports and human dynamics, 2019

Measurement of rotational property for a baseball in flight with acceleration sensors
NAGAOKA Hiroyuki; OGINO Naoya; TSUBOI Kazuhiro; NODA Shigeho; HIMENO Ryutaro,

We attempt to measure the rotational characteristics of a ball in flight by using a baseball-like ball with a built-in acceleration sensor unit which consists of one three-axis sensor for low G and three sensors for High G. Two approaches for obtaining the rotational speed and its axis of the ball from outputs of the sensors are formulated; one is based on rotational component in the acceleration outputs and the other is based on translational one. We employ in the present approaches the assumption that the time variation of rotation axis can be neglected because it is sufficiently slow. In flight experiments, we obtain nine time series data of acceleration for straight and curve ball trajectories, respectively. By using these experimental data, we estimate the rotational speed and rotation axis with the present two algorithms. As the results, it is shown that the rotation axis keeps almost constant during the flight in each algorithm's result and this means the validity of our assumption on rotation axis. The difference in the rotation axis obtained by the two algorithms ranges from 3.5 to 10.6 degrees in the straight ball data while it does from 3.9 to 18.8 degrees in the data of curve ball. Also, the averaged rotational speed in the nine trials is 12.56 rps in the straight data, and the difference between the algorithms indicates 0.10 rps (after pitching) and 0.17 rps (before catching). In the curve ball data, the averaged value and the difference between the algorithms are 19.22 rps, 0.10 rps (after pitching) and 0.14 rps (before catching), respectively. The present result shows the decrease of the rotational speed along flight trajectories, and it is probably the effect of aerodynamic torque.

, The Japan Society of Mechanical Engineers
Transactions of the JSME (in Japanese), 2019, [Reviewed]

A Model for Merging Sections in Transportation Systems and Its Analysis
Takahiro Hoshino; Chuan Tian; Takafumi Komuro; Kazuhiro Tsuboi; Yoshio Hamamatsu
ELECTRONICS AND COMMUNICATIONS IN JAPAN, Sep. 2016, [Reviewed]

Merging Control Strategy with a Waiting-time Limit in a Personal Rapid Transit System　　　　　　　　　　　　　　　
Takafumi KOMURO; Kazuhiro TSUBOI; Takahiro HOSHINO; Yoshio HAMAMATSU, The Institute of Electrical Engineers of Japan
The International Conference on Electrical Engineering 2016, 06 Jul. 2016, [Reviewed]

A Metaheuristic Algorithm with Hybrid Insertion Procedure for the Traveling Salesman Problem
Takahiro Hoshino; Chuan Tian; Hisashi Kondo; Kazuhiro Tsuboi; Yoshio Hamamatsu
International Journal of Computer Science Issues, May 2016, [Reviewed]

Optimum Angle in Projection with Initial Speed \Depending on Angle
Kazuhiro Tsuboi; Takahiro Hoshino; Yoshio Hamamatsu, Lead, We investigate a simple mechanical model in which a particle is projected from a platform moving horizontally with constant speed. This projection model has three variables and includes the constraint between the initial speed and initial angle appeared in the projection with run-up effect in sports. Under the initial condition given by this model, we derive analytically the projection angle at which the flight distance is maximized. The result shows that the present mechanism based on the elementary mechanics explains successfully the well-known angles observed in actual situations., The Japan Society for Industrial and Applied Mathematics
日本応用数理学会論文誌, Dec. 2015, [Reviewed]

A control strategy with a waiting time limit at a merging section in a personal rapid transit system
Takafumi Komuro; Takahiro Hoshino; Kazuhiro Tsuboi; Yoshio Hamamatsu, Institute of Electrical Engineers of Japan
IEEJ Transactions on Industry Applications, 01 Dec. 2015, [Reviewed]

A model for merging sections in transportation systems and its analysis
Takahiro Hoshino; Chuan Tian; Takafumi Komuro; Kazuhiro Tsuboi; Yoshio Hamamatsu, Institute of Electrical Engineers of Japan
IEEJ Transactions on Industry Applications, 01 Feb. 2015, [Reviewed]

Estimation of aerodynamic coefficients for a ball by using characteristics of trajectory
Kaito YASUDA; Kazuhiro TSUBOI; Kohei TANAKA and Takeshi MIYAZAKI, Corresponding, スポーツで使用されるボールの空力係数を飛翔中の軌道形状データから求める方法を検証した．軌道形状の特徴量として，大域的形状を表わす量（飛距離や最大高さなど）と局所的に決まる量（曲率や捩率など）をそれぞれ考えた．前者を用いた方法では，特徴量の実測値と運動方程式による予測値の誤差を最小化することで空力係数を決定した．この方法でサッカーボールの空力係数の推定を行い妥当な結果が得られた．また，後者に基づく方法では空間曲線論を用いて局所的量と空力係数を関連付けた．この方法を卓球ボールの測定結果に適用することで，軌道に沿った空力係数の変化を評価することができた．, The Japan Society of Mechanical Engineers
Transactions of the JSME (in Japanese), 25 Jun. 2014, [Reviewed]

Aerodynamic Coefficients Estimation based on Local Geometry of Ball Trajectory　　　　　　　　　　　　　　　
Kazuhiro Tsuboi and Kaito Yasuda, Lead
Proceedings of the International Association of Computer Science in Sport Conference (IACSS2014), 22 Jun. 2014, [Reviewed]

Analysis of traffic congestion by considering merging on entry lines in transportation system
Takahiro Hoshino; Kazuhiro Tsuboi; Yoshio Hamamatsu
ELECTRONICS AND COMMUNICATIONS IN JAPAN, Aug. 2012, [Reviewed]

Application of Eulerian Approach to Simulate Hard Rime Accretion
Kazuhiro Tsuboi & Shigeo Kimura, Lead
Journal of Adhesion Science and Technology, 24 Jul. 2012, [Reviewed]

The Maximum Projection Angle of a Projectile under Drag and Lift
Kazuhiro TSUBOI, Lead, 抵抗係数と揚力係数が一定の空気力が働く投射体の軌道を質点の運動で近似し，その最大投射角について考察した．速度に比例する空気力の働く質点の運動方程式から最大投射角を抵抗係数と揚力係数の摂動解として第２次項まで求めた．また，速度の自乗に比例する空気力に対する運動方程式から最大投射角の数値解を求めた．これらから抵抗と揚力が最大投射角に与える影響を評価した結果，空気力により最大投射角は減少する，減少の程度は抵抗より揚力の方が大きい，最大投射角は抵抗係数と揚力係数の2次式によって近似できる，などの結論が得られた, The Japan Society of Mechanical Engineers
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C, 25 Jun. 2012, [Reviewed]

Application of Eulerian approach to simulate hard rime accretion
Kazuhiro Tsuboi; Shigeo Kimura
Journal of Adhesion Science and Technology, 01 Mar. 2012, [Reviewed]

Operation of Vehicles in AGV System and Method for Analyzing Operation
Takahiro Hoshino; Kazuhiro Tsuboi; Kazuo Yamanaka; Yoshio Hamamatsu
ELECTRICAL ENGINEERING IN JAPAN, Jan. 2012, [Reviewed]

Application of a Projection Model Including the Effect of Run-Up to Sports Activities
Kazuhiro TSUBOI and Yasuaki KONAGAYA, Lead, スポーツ競技で見られる助走を伴う投射に対する力学モデルとして３変数モデルを考察した．このモデルには投射時の水平速度，投射速度，投射角の3変数が含まれ，これらによって人体の体幹部と肢体の動きに付随する最小限の自由度を表現される．３変数投射モデルから初速度と初速角の間の関係式を導出し，それが助走を伴う投射に適した関数形であることを確認した．砲丸投げと走り幅跳びの実測データによる拘束条件と比較し，３変数モデルから最適初速角や最適初速度が推定できることを示した．このことから３変数モデルは初速度と初速角の間の拘束条件を含んだ投射モデルと考えることができ，助走を伴う投射モデルに対する力学的根拠を与える．, The Japan Society of Mechanical Engineers
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C, 25 Oct. 2011, [Reviewed]

Characterization of Throwing Technique in Shot Put by Using Release Model with Three Degrees of Freedom
TSUBOI Kazuhiro, Lead, 助走の効果を含む３自由度投射モデルによって砲丸投げ投法の力学的差異について考察した．このモデルは砲丸の押し出し速度，押し出し角と助走の効果を表わす身体の移動速度からなる3個のパラメータで表現される．投射が最適な角度で行われたと仮定して，実測値からこれらのパラメータ値を推定した．その結果，押し出し速度と身体移動速度の間には投法によらず強い負の相関があり，これらの速度の間に緊密な関係があることを確認した．また，グライド投法と回転投法では身体移動速度の分布や最適押し出し角に違いがあることがわかった．このことは３自由度投射モデルによる砲丸投げ投法の力学的な特徴付けの可能性を示唆する結果と考えられる．, The Japan Society of Mechanical Engineers
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C, Mar. 2011, [Reviewed]

Analysis of traffic congestion by considering merging on entry lines in transportation system
Takahiro Hoshino; Kazuhiro Tsuboi; Yoshio Hamamatsu
IEEJ Transactions on Industry Applications, 2011, [Reviewed]

A mathematical solution of the optimum takeoff angle in long jump
Kazuhiro Tsuboi
ENGINEERING OF SPORT 8: ENGINEERING EMOTION - 8TH CONFERENCE OF THE INTERNATIONAL SPORTS ENGINEERING ASSOCIATION (ISEA), 2010, [Reviewed]

Operation of Vehicles in AGV System and Method for Analyzing the Operation　　　　　　　　　　　　　　　
HOSHINO Takahiro; TSUBOI Kazuhiro; YAMANAKA Kazuo; HAMAMATSU Yoshio
IEEJ Trans. IA, 2009, [Reviewed]

The Optimum Angle of Takeoff in Long Jump with Vertical Displacement at Landing
TSUBOI Kazuhiro, Lead, In long jump, it is possible to estimate a distance between takeoff and landing by assuming that the center of mass of a long jumper in aerial phase moves along a trajectory of projectile. Based on the assumption, we obtain an approximate trajectory of the jumper as a perturbed solution of flat aerial path, in which the effect of air drag is included as the linear form. Also, a maximization problem is formulated from the trajectory and the optimum angle of takeoff is theoretically derived. Then, we introduce two parameters, the horizontal velocity of the center of mass and the takeoff velocity into the present model of takeoff. In particular, the solution of the optimum angle includes the effect of vertical displacement at landing which affects significantly a distance of the aerial phase. The distance of the aerial phase and the takeoff angle are estimated in several cases of measured data. The results of the estimation show the effectiveness of the present solutions., The Japan Society of Mechanical Engineers
日本機械学会論文集Ｃ編, Jul. 2008, [Reviewed]

A Study of a Merging Section of PRT System with Bulk Arrival and Its Control Strategy　　　　　　　　　　　　　　　
HOSHINO Takahiro; INOUE Kousuke; TSUBOI Kazuhiro; HAMAMATSU Yoshio, This paper deals with a merging section of Personal Rapid Transit system with bulk arrival. Vehicles
arrive at a merging section from a main line and a sub line. Basically, vehicles on the main line have priority.
Therefore a queue is formed only on the sub line. In this situation, the queuing delay on the sub line may
become extremely long. We propose a control strategy whereby vehicles on the main line are usually not
stopped; vehicles on the main line are only stopped when the number of waiting vehicles on the sub line
exceeds some specific number. This specific number is a sort of threshold. Thus, queues are formed on the
main line and the sub line, respectively. The both of queuing delays are controlled by the threshold. The
optimal value of threshold is obtained from the result of analyzing the Markov chain model.
IEEJ Trans. IA, 2008, [Reviewed]

Lateral Excitation between Dissimilar Orientation Columns for Ongoing Subthreshold Membrane Oscillations in Primary Visual Cortex
NAKAMURA Yuto; TSUBOI Kazuhiro and HOSHINO Osamu
Artificial Neural Networks - ICANN 2008, 2008, [Reviewed]

An analytic solution of projectile motion with the quadratic resistance law using the homotopy analysis method
Kazuki Yabushita; Mariko Yamashita; Kazuhiro Tsuboi
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL, Jul. 2007, [Reviewed]

２流体モデルによる粗氷形成の数値シミュレーション
坪井一洋; 木村茂雄, Lead, Employing unsteady 2-fluid equation of multiphase flows as a mathematical model of flows including super-cooled droplets, we apply Eulerian approach to ice-accretion problem. A coupled system of equations for airstream and suspended water droplets is solved numerically with FDM and local impingement efficiency (mass flux of droplets on a body surface) is estimated. The temporal change of the shape of accreted ice is obtained from the local impingement efficiency and the renewal of grid distribution is performed. We also describe some difficulties on Eulerian approach in icing problems. These are mathematical property of the basic equations, the deterioration of representing the body shape due to the lack of grid point and stiffness due to large difference of characteristic time scales. In particular, the second difficulty is overcome by the method for grid interpolation. Hard-rime accretion on a NACA0015 air foil is simulated by means of the present procedure. In particular, the effect of two different definitions of local impingement efficiency and two different growth directions to the accreted ice is investigated. Comparison with an experimental observation shows that the simulated ice shape of local impingement efficiency with the uniform velocity direction and normal direction growth reproduces successfully the experimental results., Japan Society for Simmulation Technology
シミュレーション, 15 Dec. 2006, [Reviewed]

風力タービンブレード上の着氷解析コードの開発　　　　　　　　　　　　　　　
木村茂雄; 佐藤威; 坪井一洋; 森川浩司
日本雪氷学会誌, Sep. 2006, [Reviewed]

Particle Density Field in Low Stokes Number Region of 2-fluid Saffman Equation
TSUBOI Kazuhiro, Lead, We investigate the density field of particle phase in low Stokes number region of 2-fluid Saffman equation which is a model of dilute particle flow on 2-fluid description with incompressible carrier flow. In the stagnation region of inviscid carrier phase, we find an exact solution of particle flow field and some features of the velocity and density fields are clarified. Furthermore, we reconsider Michael's criteria on the appearance of particle free layer. The order estimation of particle velocity field leads to the new criteria δ<κτ (δ,κ and τindicate the thickness of viscous boundary layer, the curvature and Stokes number) and computational results support the present criteria., The Japan Society for Industrial and Applied Mathematics
日本応用数理学会論文誌, Mar. 2006, [Reviewed]

Computational Investigation on Flow Field of Particle Phase in 2-fluid Saffman Equation
TSUBOI Kazuhiro, Lead
AIAA paper, Jun. 2004, [Reviewed]

Density Distribution in Stagnation Region of Saffman Eqaution for Dusty Gas
TSUBOI Kazuhiro, Lead
ASME PVP, Aug. 2002, [Reviewed]

Aerodynamic characteristics of an iced cup-shaped body
KIMURA Shigeo; ABE ken'ichi; TSUBOI Kazuhiro; Tammelin Bengt; SUZUKI Kohji
Cold Regions Science and Technology, Oct. 2001, [Reviewed]

Particle flow around an oscillating Circular Cylinder based on two-fluid model
TSUBOI Kazuhiro; KIMURA Shigeo, Lead, Proc. the 3rd Int. Symp. on Computational Technologies for Fluid/Thermal/Chemical Systems with Industrial Applications, Volume 1
ASME PVP, Jul. 2001, [Reviewed]

Computational and Analytical Study on Particle Flow Field around a Circular Cylinder
TSUBOI Kazuhiro, Lead
AIAA paper, 2001, [Reviewed]

Condition Number of Tridiagonal Matrix in Stretching Coordinates System
坪井一洋, Lead, We investigate a condition number based on Enclidian norm of tridiagonal matrix which is obtained by discretizing Laplacian operator defined in one-dimensional general coordinate system. A particular stretching transformation of exponential function makes possible the analytical estimation of upper and lower bounds of the condition number. We also clarify the asymptotic behaviour of the condition number in large values of the transformation parameter, which shows the condition number comes close to the lower bound., The Japan Society for Industrial and Applied Mathematics
Transactions of Japan Society for Industrial and Applied Mathematics, 2000, [Reviewed]

Computational Study on Local Impingement Efficiency of an Oscillating Circular Cylinder　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KIMURA Shigeo, Lead
AIAA paper, 2000, [Reviewed]

Investigation on Ice Accretion Rate of Oscillating Body　　　　　　　　　　　　　　　
坪井一洋; 木村茂雄, Lead
Journal of Japan Society of Fluid Mechanics, 1999

Numerical Simulation of Ice Accretion on a Body with Droplet Flow Model
TSUBOI Kazuhiro; KIMURA Shigeo, Lead
AIAA paper, 1999, [Reviewed]

Numerical Study of the Effect of Droplet Distribution in Incompressible Droplet Flows
Tsuboi Kazuhiro; Kimura Shigeo, Lead, American Institute of Aeronautics and Astronautics Inc.
AIAA paper, Jun. 1998

装置周辺の空気の流れの可制御性とその制御法の一提案
白石昌武; 出山浩行; 柴田智和; 坪井一洋, Air fluctuation around the fine equipment system seems to be a kind of extremely low velocity air flow and is one of the major causes in deteriorating system working accuracies. Unfortunately there is no active means to control air fluctuation at present. This paper describes the controllability of air flow around the equipment assuming that the air flow dynamics is approximated by a linear equation under the low velocity viscous flow condition. With the verification of its controllability, several experiments are performed to confirm the possibility of air flow control by using smoke particles. Specifically, smoke particles are stimulated by the optical radiation pressure of Ar laser beam. Their behaviors are regulated by the optical system such as a convex lens and an ND filter with the number of stimulated smoke particles. The experimental results basically show the possibility of air flow control using an optical radiation pressure., The Japan Society for Precision Engineering
精密工学会誌, 05 May 1998, [Reviewed]

Formulation of Basic equations of Droplet flows with the Diameter Distribution　　　　　　　　　　　　　　　
Lead
Proceediugs of The Third International Confenence on Fluid Mechanics, Beijing, 1998

ゆっくり変動するモード間の共振的結合を伴う非線型偏微分方程式の数値シミュレーション
坪井一洋; ミハエル・トリベルスキー, Lead, A new approach to numerical integration of nonlinear PDE with two resonantly-coupling bands of slowly evolving modes, originated in the problem's symmetry, is developed. The bands are centered around a certain finite wavenumber and wavenumber equal to zero, respectively, that gives rise to a complicated spatiotemporal behaviour of solutions. The approach is based on reduction of the problem to a truncated set of coupled equations for Fourier-transforms of the order parameter supplemented, by exclusion of the slaved mode. Though the basic equation is stiff, an explicit time marching by Runge-Kutta method with some techniques is successfully performed. Application of the approach to the particular equation governing seismic waves yields solutions that display a new type of turbulence., The Japan Society for Industrial and Applied Mathematics
日本応用数理学会論文誌, 1997

On the Optimum Angle of Takeoff in Long jump.
坪井一洋, Lead, An approximate solution of orbit for long jump from takeoff to landing is obtained by considering the orbit as a projectile of a particle. The effect of air-drag is included as the linear form. Comparison with the exact solution of numerical integration shows the solution has good accuracy. Based on the solution, we can determine the optimum angle of takeoff successfully and esrimate the value from measured data., The Japan Society for Industrial and Applied Mathematics
Transactious of Japan Society for Industrial and Applied Mathematics., 1996, [Reviewed]

New Scenario for Transition to Turbulence ?
Michael Tribelsky; Kazuhiro Tsuboi
Physical Review Letters, 1996

天文台ドーム内の3次元流れに関する数値実験
坪井一洋; 宮腰佳代; 長澤幹夫; 海部宣男; 桑原邦郎, Lead
日本流体力学会誌「ながれ」, 1993, [Reviewed]

Computational Study of unsteady viscous flow around a transversely and longitudinally oscillating circular cylinder in a uniform flow at high Reynolds numbers　　　　　　　　　　　　　　　
RAO P. M.; KUWAHARA Kunio; TSUBOI Kazuhiro
Computational Mechanics, Jun. 1992, [Reviewed]

Simulation of unsteady viscous flow around a lon-gitudinally oscillating cir-cular cylinder in a uniform flow.
P. M. Rao; Kunio KUWAHARA; Kazuhiro TSUBOI
Appl. Mech. Modelling, Jan. 1992, [Reviewed]

An approach to incompressible flow problems with a massively parallel computer
TSUBOI Kazuhiro; MIYAKOSHI Kayo; KUWAHARA Kunio, Lead
Proceedings of Parallel Computational Fluid Dynamics '91, Elsevier, 1992, [Reviewed]

Incompressible flow simulations with solid models in rectangular grid system
TSUBOI Kazuhiro; MIYAKOSHI Kayo; KUWAHARA Kunio, Lead
Numerical Grid Generation in Computational Fluid Dynamics and Related Fields, North-Holand, 1991, [Reviewed]

Incompressible Flow Simulation of Complicated Boundary Problems with Rectangular Grid System
TSUBOI Kazuhiro; MIYAKOSHI Kayo; KUWAHARA Kunio, Lead
Theoretical and Applied Mechanics, 1991

INCOMPRESSIBLE-FLOW SIMULATION OF COMPLICATED BOUNDARY-PROBLEMS WITH RECTANGULAR GRID SYSTEM
K TSUBOI; K MIYAKOSHI; K KUWAHARA
THEORETICAL AND APPLIED MECHANICS, VOL 40, 1991, [Reviewed]

Numerical Simulation of Unsteady Flow Patterns around a Vibrating Cylinder
T. Tamura; K.Tsuboi; K. Kuwahara, 26th Aerospace Sciences Meeting,
AIAA-88-0128, pp. 1-11.
AIAA paper, Jan. 1988

Computational Study of the Effect of Base Slant
TSUBOI Kazuhiro; SHIRAYAMA Susumu; OANA M.; KUWAHARA Kunio, Lead, Proc. 2-nd Int. Conf. on Supercomputing Application and Automotive Industry, Cray Research, Inc., Cray Research Inc.
Supercomputer Applications in Automotive Research and Engineering Development, ed. C. Marino, North-Holland, 1988

Numerical Study of Two-dimensional Vortex Street　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; OHSHIMA Yuko, Lead
Numerical Methods in Fluid Mechanics, Oct. 1986, [Reviewed], [Invited]

Computational Study of the Effect of Base Slant　　　　　　　　　　　　　　　
K. Tsuboi; R. Himeno; S. Shirayama; K. Kuwahara, Lead, ASME/AIAA 4th Fluid Mechanics, Plasma Dy-namics and Lasers Conference
AIAA paper, May 1986, [Reviewed]

Merging of Two Dimensional Vortices by the Discrete Vortex Method
TSUBOI Kazuhiro; OHSHIMA Yuko, Lead
Journal of the Physical Society of Japan, 1985

書評「2点境界値問題の数理」
坪井 一洋
応用数理, Mar. 2007
Lead

着氷のシミュレーション　　　　　　　　　　　　　　　
木村茂雄; 坪井一洋
シミュレーション, Mar. 2001, [Reviewed]

Fluid dynamics and Parallel computation　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KUWAHARA Kunio
Computrol, 1992
Lead

Numerical Study of Two-dimensional Vortex Street
TSUBOI Kazuhiro; OSHIMA Koichi
The Institute of Space and Astronautical Science Report SP, Mar. 1985, [Reviewed]
Lead

〔Major achievements〕システムと微分方程式 第2版　　　　　　　　　　　　　　　
坪井一洋, Single work
三恵社, 01 Oct. 2019
9784866931159

システムと微分方程式　　　　　　　　　　　　　　　
坪井一洋, Single work
三恵社, 01 Apr. 2011
9784883618248

Application of Bayesian Linear Regression to Aerodynamic Analysis Using Trajectory Data　　　　　　　　　　　　　　　
Shinya FUKUOKA; Koudai SUGIHARA; Kazuhiro TSUBOI
Symposyum: Sports Engineering and Human Dynamics 2024, 16 Nov. 2024
20241115, 20241117

Application of Machine Learning to Trajectory Analysis in Aerodynamics　　　　　　　　　　　　　　　
Shota SEKINO; Kazuhiro TSUBOI
Symposyum: Sports Engineering and Human Dynamics 2024, 16 Nov. 2024
20241115, 20241117

Specification Classification based on ITR Data Using Machine Learning　　　　　　　　　　　　　　　
Shota SEKINO; Kazuhiro TSUBOI
The 32nd Ibaraki District Conference, 30 Aug. 2024
20240830, 20240830

Estimation of Unsteady Aerodynamic Characteristics based on Three-Dimensional Data of Golf Ball in Flight　　　　　　　　　　　　　　　
Kengo OKAZAKI; Kouki MURAKAMI; Kazuhiro TSUBOI
The 32nd Ibaraki District Conference, 30 Aug. 2024
20240830, 20240830

Estimation Method of Unsteady Aerodynamics in Projectile using Trajectory Analysis　　　　　　　　　　　　　　　
Koki MURAKAMI and Kazuhiro TSUBOI
日本機械学会 2023 年度茨城講演会, 18 Aug. 2023, 日本機械学会関東支部，精密工学会
20230818, 20230818

Feature Selection in Estimation of Aerodynamic Force with Machine Learning　　　　　　　　　　　　　　　
Shota SEKINO and Kazuhiro TSUBOI
日本機械学会 2023 年度茨城講演会, 18 Aug. 2023, 日本機械学会関東支部，精密工学会
20230818, 20230818

Parameter Estimation of Initial Value Problems by Approximate Bayesian Computation　　　　　　　　　　　　　　　
Shinya FUKUOKA and Kazuhiro TSUBOI
日本機械学会 2023 年度茨城講演会, 18 Aug. 2023, 日本機械学会関東支部，精密工学会
20230818, 20230818

On the Estimation of Aerodynamic Properties in Flight Experiment
Kazuhiro TSUBOI
日本流体力学会年会2022, 27 Sep. 2022, 日本流体力学会
20220927, 20220929

Estimation of Unsteady Aerodynamic Characteristics in Balls based on Geometry of Flight Trajectory　　　　　　　　　　　　　　　
Kazuma MORIMURA and Kazuhiro TSUBOI
JSME Symposium : Sports engineering and Human Dynamics 2021, 13 Nov. 2021, The Japan Society of Mechanical Engineers
20211112, 20211114

Verification of acceleration in flight of baseball-type accelerometer using its output simulation　　　　　　　　　　　　　　　
Rio HIYAMA; Kazuhiro TSUBOI; Shigeho NODA and Ryutaro HIMENO
JSME Symposium : Sports engineering and Human Dynamics 2021, 13 Nov. 2021, The Japan Society of Mechanical Engineers
20211112, 20211114

Aerodynamic Characteristics of a Projectile Estimated from Its Trajectory　　　　　　　　　　　　　　　
Kazuki AIZAWA; Kazuhiro TSUBOI and Koujin TAKEDA
日本機械学会 2021年度茨城講演会, 21 Aug. 2021, 日本機械学会
20210819, 20210819

Application of Approximate Bayesian Computation to,Trajectory-based Estimation of Aerodynamic Coefficients　　　　　　　　　　　　　　　
Masato ISHITSUKA; Kazuhiro TSUBOI; Koujin TAKEDA and Takeshi MIYAZAKI
JSME Symposium : Sports engineering and Human Dynamics 2020, 14 Nov. 2020, 日本機械学会
20201113, 20201115

Simulation of Outputs in Baseball-type Acceleration Sensor　　　　　　　　　　　　　　　
Rio HIYAMA; Hiroyuki NAGAOKA; Kazuhiro TSUBOI; Shigeho NODA and Ryutaro HIMENO
日本機械学会 2020年度茨城講演会, 21 Aug. 2020, 日本機械学会
20200821, 20200821

Aerodynamic Characteristics of a Projectile Estimated from Its Trajectory　　　　　　　　　　　　　　　
Kazuma MORIMURA and Kazuhiro TSUBOI
日本機械学会 2020年度茨城講演会, 21 Aug. 2020, 日本機械学会
20200821, 20200821

Rotational property of a ball in flight by using built-in acceleration sensors　　　　　　　　　　　　　　　
Hiroyuki NAGAOKA; Rio HIYAMA; Kazuhiro TSUBOI; Shigeho NODA and Ryutaro HIMENO
JSME Symposium : Sports engineering and Human Dynamics 2019, 27 Oct. 2019, 日本機械学会

Measurement of Three-dimensional Trajectory of Ball in Flight and Estimation of Its Aerodynamic Coefficients　　　　　　　　　　　　　　　
Takumi MIURA; Kazuma MORIMURA; Kazuhiro TSUBOI and Nobuyuki UMEDU
JSME Symposium : Sports engineering and Human Dynamics 2019, 27 Oct. 2019, 日本機械学会

Projection model with velocity composition and its projection angle for particle　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
日本物理学会 2018年秋季大会, 09 Sep. 2018, 日本物理学会

Measurement of rotational property for a baseball in flight with acceleration sensors　　　　　　　　　　　　　　　
Hiroyuki NAGAOKA; Naoya OGINO; Kazuhiro TSUBOI; Shigeho NODA and Ryutaro HIMENO
Dynamics and Design Conference 2018, 30 Aug. 2018, 日本機械学会

Error analysis of aerodynamic force estimation for balls by flight experiment　　　　　　　　　　　　　　　
坪井一洋; 渡辺卓馬; 宮嵜武
JSME Symposium : Sports engineering and Human Dynamics 2017, 10 Nov. 2017, 日本機械学会

Estimation of aerodynamic coefficients for balls in flight with trajectory data　　　　　　　　　　　　　　　
渡辺卓馬; 荒木田祐希; 坪井一洋
JSME Symposium : Sports engineering and Human Dynamics 2016, 10 Nov. 2016, 日本機械学会

Optimum angle in extended projection model for point mass　　　　　　　　　　　　　　　
Kazuhiro;Tsuboi
日本物理学会2016年秋季大会, 15 Sep. 2016, 日本物理学会

Optimum angle in projectile motion,–Optimization problem in elementary mechanics –　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
Mechanical Engineering Congress, 2015 Japan (MECJ-15), 15 Sep. 2015, The Japan Socoety of Mechanical Engineers

A Merging Control Strategy based on Waiting Time Limit on Personal Rapid Transit System　　　　　　　　　　　　　　　
Takafumi KOMURO; Takahiro HOSHINO; Kazuhiro TSUBOI; Yoshio HAMAMATSU
第22回電気学会東京支部茨城支所研究発表会, 22 Nov. 2014, 電気学会東京支部茨城支所

角度に依存する初速度をもつ放物運動の最大投射角　　　　　　　　　　　　　　　
Kazuhiro TSUBOI; Takahiro HISHINO
日本応用数理学会2014年度年会, 05 Sep. 2014, 日本応用数理学会

Estimating method of aerodynamic coefficients for a projectile with trajectories　　　　　　　　　　　　　　　
Kaito YASUDA; Kazuhiro TSUBOI; Kohei TANAKA and Takeshi MIYAZAKI
JSME Symposium:Sports and Human Dynamics 2013, 03 Nov. 2013, 日本機械学会

Object-oriented simulation for soccer play　　　　　　　　　　　　　　　
中村 翔吾; 坪井 一洋
日本機械学会 2012 茨城講演会, 24 Aug. 2012, 日本機械学会

An estimating method of aerodynamic coefficients for soccer ball　　　　　　　　　　　　　　　
安田 海人; 坪井 一洋
日本機械学会 2012 茨城講演会, 24 Aug. 2012, 日本機械学会

２流体モデルによる着氷シミュレーションとその課題　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
第3回着氷研究会, 18 Jul. 2012

The maximum projection angle for a ball acting on drag and lift　　　　　　　　　　　　　　　
坪井 一洋; 鈴木 悠太
シンポジウム：スポーツ・アンド・ヒューマン・ダイナミクス2011, 02 Nov. 2011, 日本機械学会

Characterization of throwing technique in shot put by using release model with run-up　　　　　　　　　　　　　　　
坪井 一洋; 小長谷 康明
シンポジウム：スポーツ・アンド・ヒューマン・ダイナミクス2010, 05 Nov. 2010, 日本機械学会

Verification of take-off model with three degrees of freedom in long jump　　　　　　　　　　　　　　　
小長谷 康明; 坪井 一洋
シンポジウム：スポーツ・アンド・ヒューマン・ダイナミクス2010, 04 Nov. 2010, 日本機会学会

Analysis of Queuing Model with Multi-Input　　　　　　　　　　　　　　　
星野貴弘; 坪井一洋; 浜松芳夫
日本応用数理学会2010年度年会, 09 Sep. 2010, 日本応用数理学会

A mathematical solution of the optimum takeoff angle in long jump　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
8th Conference of the International Sports Engineering Association, 15 Jul. 2010, The International Sports Engineering Association

Weak solution of inviscid Burgers equation with a finite conserved quantity　　　　　　　　　　　　　　　
LI Jing; SAITO Masamitsu; TSUBOI Kazuhiro
日本機械学会関東支部第16期総会講演会, 11 Mar. 2010, 日本機械学会関東支部

Application of Optimization Technique to Solution of Incompressible Navier-Stokes Equation　　　　　　　　　　　　　　　
Kazuhiro Tsuboi; Kenji Sasajima
5th AIAA Theoretical Fluid Mechanics Conference, 24 Jun. 2008, 米国航空宇宙学会

Application of a computational method for incompressible flow based on optimization technique to plane Poiseuille problem　　　　　　　　　　　　　　　
笹島健司; 坪井一洋
第21回数値流体力学シンポジウム, 21 Dec. 2007, 日本流体力学会

Optimum takeoff angle in long jump with vertical displacement at landing　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; TAKAHASHI Syunsuke
ジョイント・シンポジウム2007 スポーツ工学シンポジウム／シンポジウム：ヒューマン・ダイナミクス, 15 Nov. 2007, （社）日本機械学会

Some Remarks on Basic Equations of Eulerian Approach in Icing Problems　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KIMURA Shigeo
12th International Workshop on Atmospheric Icing on Structures (IWAIS2007), 10 Oct. 2007

On the Density of Dispersed Phase in an Equation of 2-fluid Description　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
日本応用数理学会2007年度年会, 17 Sep. 2007, 日本応用数理学会

現代制御理論に基づく非圧縮性流れの新しい計算法　　　　　　　　　　　　　　　
SASAJIMA Kenji and TSUBOI Kazuhiro
第26回日本シミュレーション学会大会, 22 Jun. 2007, 日本シミュレーション学会

最適化手法に基づく非圧縮性Navier-Stokes方程式の計算法　　　　　　　　　　　　　　　
笹島 健司; 坪井 一洋
第20回数値流体力学シンポジウム講演論文集, 18 Dec. 2006

空気抵抗が速度の２乗に比例する場合の放物運動の解析解とその性質　　　　　　　　　　　　　　　
山下真理子; 藪下和樹; 坪井一洋; 岡畑豪
日本応用数理学会2006年度年会講演予稿集, 17 Sep. 2006

最適化手法に基づく定常非圧縮性流れの計算法　　　　　　　　　　　　　　　
坪井一洋; 笹島健司
日本応用数理学会2006年度年会講演予稿集, 16 Sep. 2006

Computaional method of incompressible flow with optimization technique　　　　　　　　　　　　　　　
Sasajima Kenji; Satoh Yohsuke; Tsuboi kazuhiro
第25回日本シミュレーション学会大会発表論文集, 23 Jun. 2006

Numerical simulation of hard-rime accretion based on 2-fluid model　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KIMURA Shigeo
第43回日本伝熱シンポジウム講演論文集, 01 Jun. 2006

An Analytic Solution of Projectile Motion Equation Using Homotopy Analysis Method - The Case of the Quadratic Resistance Law -　　　　　　　　　　　　　　　
YAMASHITA Mariko; YABUSHITA Kazuki; TSUBOI Kazuhiro
Proceedings of the 55th Nat. Cong. of Theoretical and Applied Mechanics 2006, Jan. 2006

Computation of Incompressible Flows based on Rotational Form of NS Equation　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
Proceedings of 2005 Annual Meeting, Japan Society of Fluid Mechanics, 07 Sep. 2005

Asynchronous Parallel computation with distributed Domain-object　　　　　　　　　　　　　　　
KOBAYASHI Iori; TSUBOI Kazuhiro
第24回日本シミュレーション学会大会発表論文集, 15 Jul. 2005

Calculation of Traffic Eqaution by TVD Finite Difference Method　　　　　　　　　　　　　　　
OHSHIO Teruyuki; TSUBOI Kazuhiro
第24回日本シミュレーション学会大会発表論文集, 14 Jul. 2005

Computational method of incompressible flow with basic equation in rotational form　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
第54回理論応用力学講演会講演論文集, 26 Jan. 2005

Numerical solution on 2-fluid equation of incompressible viscous main flow　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KIMURA Shigeo
日本流体力学会２００４講演論文集, 11 Aug. 2004

Finite difference solution of traffic flow with traffic signal　　　　　　　　　　　　　　　
TOMIZAWA Tetsuro; TSUBOI Kazuhiro; NAKATA Tetsuya
第23回日本シミュレーション学会大会発表論文集, 16 Jun. 2004

Object-oriented modeling for traffic flow simulation with fluid model　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; SUZUKI Takato
第23回日本シミュレーション学会大会発表論文集, 16 Jun. 2004

Computation on 2-fluid Saffman equation　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KIMURA Shigeo
Proceedings of the 17th Symposium on Computational Fluid Dynamics, 18 Dec. 2003

２流体モデルによる物体への着氷シミュレーション　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KIMURA Shigeo
Proceedings, 2003 Meeting of Japan Society of Fluid Mechanics, 28 Jul. 2003

Numerical simulation of ice-accretion on a body based on 2-fluid equation　　　　　　　　　　　　　　　
TSUBOI Kazuhiro; KIMURA Shigeo
Proceedings of the 22th Japan Simulation Conference, 18 Jun. 2003

Application of Domain-object to traffic flow simulation by fluid model　　　　　　　　　　　　　　　
SUZUKI Takato; TSUBOI Kazuhiro
Proceedings of the 22th Japan Simulation Conference, 18 Jun. 2003

Parallel computation with distributed Domain-object　　　　　　　　　　　　　　　
T. MITSUISHI; K. TSUBOI
第16回数値流体力学シンポジウム, 16 Dec. 2002, 日本数値流体力学会

Numerical Simulation of Ice-accretion on a circular cylinder based on 2-fluid equation　　　　　　　　　　　　　　　
K. TSUBOI; S. KIMURA
第16回数値流体力学シンポジウム, 16 Dec. 2002, 日本数値流体力学会

Computation of flows around an obstacle by 2-fluids Saffman equation　　　　　　　　　　　　　　　
TSUBOI Kazuhiro
Annual meeting of Japan Society of Fluid Mechanics, 23 Jul. 2002, 日本流体力学会

Electromagnetism　　　　　　　　　　　　　　　
Oct. 2005 - Mar. 2017
Ibaraki University

茨城大学工学部システム工学科

茨城大学工学部システム工学科

茨城大学工学部システム工学科

茨城大学教養科目（情報関連科目）

1996 - 2021, The Japan Society for Industrial and Applied Mathematics

1989 - May 2020, American Institute of Aeronautics and Astronautics

The Japan Society of Mechanical Engineers

Japan Society of Fluid Mechanics

The Physical Society of Japan

野球ボール打球シミュレータに関する研究　　　　　　　　　　　　　　　
Dec. 2024 - Jun. 2025

センサー内蔵ボールに関する共同研究　　　　　　　　　　　　　　　
Apr. 2020 - Mar. 2022

センサー内蔵ボールに関する共同研究　　　　　　　　　　　　　　　
Apr. 2017 - Mar. 2020

野球ボール打球軌道シミュレータに関する研究　　　　　　　　　　　　　　　
Jan. 2017 - Jun. 2017

着氷シミュレーションとその実用化に関する研究　　　　　　　　　　　　　　　
Sep. 2013

極地における新エネルギ導入によるエネルギ対策に関する研究　　　　　　　　　　　　　　　
Apr. 2007 - Mar. 2009

ホモトピー解析法による非線形方程式の解法　　　　　　　　　　　　　　　
Jun. 2005 - Mar. 2008

物体上の着氷雪に関する流体力学的研究　　　　　　　　　　　　　　　
Apr. 2004 - Mar. 2007

物体への着氷現象の流体力学的研究　　　　　　　　　　　　　　　
Apr. 2001 - Mar. 2004

振動物体への着氷予測に関する数値シミュレータの開発　　　　　　　　　　　　　　　
Grant-in-Aid for Scientific Research(C)
Apr. 2000 - Mar. 2002

物体への着氷現象の流体力学的研究　　　　　　　　　　　　　　　
Apr. 1998 - Mar. 2001

振動翼上の着氷とその空力特性への影響に関する研究　　　　　　　　　　　　　　　
Apr. 1997 - Mar. 1998

着氷したロータブレードの空気力学的特性に関する研究　　　　　　　　　　　　　　　
Apr. 1996 - Mar. 1998

プロ野球「飛ばないボール問題」の議論が過熱 「縫い目が0.1ミリ高いだけで大きく影響」と専門家
株式会社朝日新聞出版, AERAdot., 25 Jun. 2022, Internet

博士論文審査委員会委員　　　　　　　　　　　　　　　
Review
日本大学大学院理工学研究科, Dec. 2016 - Feb. 2017

日本機械学会関東支部第15期総会講演会　　　　　　　　　　　　　　　
Planning etc
日本機械学会, 茨城大学水戸キャンパス, 06 Mar. 2009

第18回計算力学講演会　　　　　　　　　　　　　　　
Planning etc
日本機械学会, 筑波大学春日キャンパス, 19 Nov. 2005

External examiner of Ph. D. thesis　　　　　　　　　　　　　　　
Review
University of Manitoba, Canada, Mar. 2005 - Nov. 2005