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

受賞国：日本国

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：一般社団法人 日本航空宇宙学会  

<p>Two types of wing geometries imitating wings of birds in gliding flight are analyzed with the vortex lattice method in terms of lift-drag ratio and root bending moment while varying the joint positions and joint angles under the constant lift coefficient and constant flight velocity conditions. One geometry is, what is sometimes called, a gull wing which has a dihedral inner wing and horizontal outer wing, named "DH wing." On the contrary, the other geometry is a drooped wing which has a horizontal inner wing and anhedral outer wing, named "HA wing." The lift-drag ratio of the HA wing becomes larger when the joint of the anhedral outer wing is closer to the wing tip with a larger anhedral angle, while the root bending moment of the HA wing becomes smaller when the joint of the anhedral outer wing is closer to the wing root with a larger anhedral angle. In contrast, the DH wing has no combination of a joint position and joint angle to improve the lift-drag ratio, and it is found that the HA wing effectively contributes to the reduction of the root bending moment and the lift-drag ratio compared with the DH wing.</p>

DOI： 10.2322/tjsass.64.267

Web of Science

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

This paper aims to investigate the ballistic kinetic impactor (B-KI) in order to mitigate the risks posed by a potential asteroid collision on Earth in the future.
The B-KI is a spacecraft that employs a single impulsive thrust to put the spacecraft into an orbit, which, in turn, impacts the target asteroid to deflect it from the collision route of Earth.
To evaluate the effectiveness of the B-KI, we introduce impact-geometry maps (IGMs), which visualize the achievable change in the orbital energy of the asteroid as a function of the spacecraft's semi-major axis and eccentricity. The achievable performance of the B-KI is investigated in the form of its mobility capability on the IGM.
In addition, parameters that govern the mission's feasibility, such as the spacecraft's relative impact speed and phase angle, are discussed.
We conducted a parametric study on the asteroid's orbital elements and found that the B-KI is, in fact, a better option for deflecting asteroids belonging to the Aten family at the intersection point where the radial velocity component is positive.
We also designed several fictional B-KI missions to achieve a more realistic asteroid mitigation campaign scenario.
The obtained results are compared with those of previous kinetic impactor studies that employ low-continuous-propulsion systems.
The study finally highlights that the B-KI can efficiently increase the impact efficiency and deflection distance for a part of the target asteroids.

DOI： 10.1016/j.actaastro.2021.01.027

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：一般社団法人 日本航空宇宙学会  

<p>A small airplane is strongly affected by crosswind in take-off and landing phases, because the flight velocity and gravitational force acting on it are not much larger than the crosswind velocity and aerodynamic force due to crosswind, respectively. A vertical tail volume can be decreased dramatically for a smaller airplane for the stability of lateral/directional motions. The NDD (Neutral Dihedral effect and Directional stability) airplane defined as <i>C</i>_{l_β} = <i>C</i>_{n_β} = 0 was conceived so that it has a tolerance to crosswind. An airplane without a dihedral effect and directional stability is not accepted in the current regulation for airplane design. Then, an airplane with small values of <i>C</i>_{l_β} and <i>C</i>_{n_β} has been newly proposed. All of the modes in the lateral/directional motions can converge without oscillating in the proposed airplane, named ``QNDD'' airplane, which is not observed in the NDD airplane. </p>

DOI： 10.2322/jjsass.69.24

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2514/1.A34817

Web of Science

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）  

DOI： 10.2514/1.G004867

Web of Science

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

DOI： 10.1016/j.actaastro.2019.10.001

Web of Science

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）  

DOI： 10.1109/ACCESS.2020.2994329

Web of Science

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）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本航空宇宙学会  

<p>To simulate the motion of a rotor while accelerating during slow descent, a simulation model that corrects errors in data obtained experimentally is developed in this paper. The effect caused by acceleration is expressed as errors in induced velocity and external thrust force, and defined by two correction factors. Best-fit correction factors that provide good approximations for experimental flight data of a bamboo dragonfly are searched and the effectiveness of the method proposed is shown.</p>

DOI： 10.2322/tastj.17.577

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2514/1.A33985

Web of Science

記述言語：日本語  

記述言語：英語  

Web of Science

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：公益社団法人 日本工学教育協会  

DOI： 10.20549/jseeja.2018.0_26

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本航空宇宙学会  

<p>Flying cars have been developed as next generation vehicles that enable high speed and flexible door-to-door transportations. A short take-off distance is expected to contribute to increase the possibility that flying cars will be used in our daily life. The purpose of the present study is to investigate to shorten a take-off distance of a flying car by using a wheels' driving force, propeller thrust and lift of main wings. This paper shows that accelerating the car by using wheels is efficient when the velocity is low. On the other hand, using propellers is more efficient when the car approaches to the take-off velocity. As a practical way to shorten the take-off distance, we propose a law to determine the power consumed by propellers and wheels as a function of the velocity of the flying car. Computation results show that the performance of the take-off phase of the flying car can be improved by using a high running ability of the car with wheels. </p>

DOI： 10.2322/jjsass.66.167

記述言語：英語  

DOI： 10.11511/jacc.61.0_1568

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

担当区分：筆頭著者   記述言語：英語  

担当区分：筆頭著者   記述言語：日本語  

記述言語：英語  

記述言語：日本語  

Collisions between Asteroids and Earth sometimes occur and bring severe damage to human society. Some asteroid deflection techniques to avoid the collisions have been suggested by astronomers and scientists. We discuss these techniques, especially kinetic impactor. In this paper, we think about the improvement of the kinetic impactor by using the concept of Impact Geometry Map which visualizes the maximum change of the asteroid’s orbital energy by an impact. This report suggests a method to increase the change in the orbital energy of the asteroid by using locally optimal thrust vectoring and the Impact Geometry Map. We also use time differentiation of Impact Geometry to make an efficient spacecraft orbit. Additionally, we describe a global trajectory optimization method of spacecraft to increase Impact Geometry.

DOI： 10.1299/jsmesec.2017.26.1A2

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

DOI： 10.1007/s40295-015-0081-x

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2322/tastj.14.Pd_119

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）  

Several mitigation methods have been studied to various degree of accuracy in the literature to deflect an asteroid from its collision course with the Earth. With the gravity tractor method, the gravitational attraction between the asteroid and a massive spacecraft is used to exert a small force remotely to tow the asteroid in the required direction to avoid an impact. One of the drawbacks of this method is the lack of control over the force produced as it only depends on the mass of the spacecraft and its distance from the asteroid. To overcome this, a new method was introduced: the electrostatic tractor. With this strategy, the deflection force is exerted by means of the electrostatic force produced by artificially charging both a spacecraft and the asteroid, which allows improving the achievable deflection. Our paper discusses a new computation model to investigate the asteroid charging mechanism produced by a plasma contactor placed on the surface of the asteroid. Unlike a simple estimation assuming a cohesive, conductive, and spherical asteroid, our model can handle the case of asteroids with an arbitrary complex shape by solving the Maxwell equations on a 3D mesh. Assuming a quasi-steady condition and an asteroid composed of an Ohmic material, it can be shown that solving the Maxwell equations on the 3D domain is equivalent to solving a Laplace equation for the potential field inside the asteroid. The boundary conditions are introduced by considering the interaction between the charged asteroid and the ambient plasma. This interaction is modeled by equivalent current sources into the surface elements, accounting for the contribution of free electrons, protons, secondary electrons, and photoelectrons, and constitutes a non-linear function of the potential V of the surface elements. Using a finite element approach provides a way to discretize this problem and reformulate it as an equivalent electric network. In this network, adjacent vertices in the mesh are connected via equivalent resistances, which depend on the geometry and the local material properties. Finally, a Newton method is employed to solve the non-linear boundary problem. Analysis for several asteroids are performed with our model and the results of the parametric study about the material, shape, and ambient plasma conditions are provided in the paper.

Scopus

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

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

DOI： 10.5194/angeo-31-665-2013

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）  

DOI： 10.2322/astj.12.79

開催年月日： 2022年2月

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：オンライン   国名：日本国  

開催年月日： 2020年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：On line  

開催年月日： 2020年1月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Orlando, Florida   国名：アメリカ合衆国  

開催年月日： 2018年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：山形県，山形テルサ   国名：日本国  

開催年月日： 2018年10月 - 2018年11月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Jeju Island, Korea   国名：大韓民国  

開催年月日： 2018年10月

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：福岡県久留米市   国名：日本国  

開催年月日： 2018年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：San Jose, CA, U.S.   国名：アメリカ合衆国  

開催年月日： 2018年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：San Jose, CA, U.S.  

開催年月日： 2017年12月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：三浦，マホロバマインズ三浦   国名：日本国  

開催年月日： 2017年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：京都府，京都大学 桂キャンパスCクラスター   国名：日本国  

開催年月日： 2017年5月

記述言語：英語   会議種別：ポスター発表  

開催地：Tokyo, Japan   国名：日本国  

開催年月日： 2017年2月

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：東京，一橋大学   国名：日本国  

記述言語：英語   会議種別：口頭発表（一般）  

開催地：San Jose, CA, U.S.