宇宙科学広報・普及主幹付

小平 將裕

コヒラ マサヒロ  (Masahiro KOHIRA)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所

J-GLOBAL ID
202001017096347690
researchmap会員ID
R000007241

論文

 9
  • Masahiro I. Kohira, Hiroyuki Kitahata, Nobuyuki Magome, Kenichi Yoshikawa
    PHYSICAL REVIEW E 85(2) 2012年2月  査読有り
    An oscillatory system called a plastic bottle oscillator is studied, in which the downflow of water and upflow of air alternate periodically in an upside-down plastic bottle containing water. It is demonstrated that a coupled two-bottle system exhibits in- and antiphase synchronization according to the nature of coupling. A simple ordinary differential equation is deduced to interpret the characteristics of a single oscillator. This model is also extended to coupled oscillators, and the model reproduces the essential features of the experimental observations.
  • Shun N. Watanabe, Takafumi Iwaki, Masahiro I. Kohira, Nobuyuki Magome, Kenichi Yoshikawa
    CHEMICAL PHYSICS LETTERS 511(4-6) 447-451 2011年8月  査読有り
    We observed the photophoresis of smoke particles in a small focal laser beam under micro-gravity, exerted in an airplane, to avoid air convectional flow due to buoyancy. We measured the motion of smoke particles and found that the particles exhibit negative photophoresis under the suppression of the convection. Based on the distribution of velocity of negative photophoresis, it is shown that the photophoretic velocity is proportional to the laser power applied for the particle. We discuss the mechanism in terms of the radiometric force. (C) 2011 Elsevier B.V. All rights reserved.
  • Masahiro I. Kohira, Nobuyuki Magome, Shin-Ichiro Mouri, Hiroyuki Kitahata, Kenichi Yoshikawa
    INTERNATIONAL JOURNAL OF UNCONVENTIONAL COMPUTING 5(1) 103-111 2009年  査読有り
    When a plastic bottle with water is placed upside-down with a thin pipe at its head. limit-cycle oscillation call be observed. A simple differential equation can reproduce the properties of this oscillation. In the present study, a three-coupled-oscillator system is investigated experimentally and numerically. The behavior of the three coupled oscillators with frustration is interesting from the viewpoint of mathematical physics, and with all increase in size, this system should be helpful in unconventional computing, such Lis in, for example, optimization problems.
  • Masahiro I. Kohira, Nobuyuki Magome, Hiroyuki Kitahata, Kenichi Yoshikawa
    AMERICAN JOURNAL OF PHYSICS 75(10) 893-895 2007年10月  査読有り
    The oscillatory flow of water draining from an upside-down plastic bottle with a thin pipe attached to its head is studied as an example of a dissipative structure generated under far-from-equilibrium conditions. Mode bifurcation was observed in the water/air flow: no flow, oscillatory flow, and counter flow were found when the inner diameter of the thin pipe was changed. The modes are stable against perturbations. A coupled two-bottle system exhibits either in-phase or anti-phase self-synchronization. These characteristic behaviors imply that the essential features of the oscillatory flow in a single bottle system can be described as a limit-cycle oscillation. (c) 2007 American Association of Physics Teachers.
  • Akihiro Isomura, Nobuyuki Magome, Masahiro I. Kohira, Kenichi Yoshikawa
    CHEMICAL PHYSICS LETTERS 429(1-3) 321-325 2006年9月  査読有り
    To identify the optimum conditions for the optical trapping of a droplet under microgravity, we theoretically analyzed the efficiency of trapping with counter laser beams. We found that the distance between the two foci is an important parameter for obtaining stable trapping conditions. We also performed an optical trapping experiment with counter laser beams under microgravity. The experimental results correspond well to the theoretical prediction. (c) 2006 Elsevier B.V. All rights reserved.

MISC

 19