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A numerical model was developed to analyze the influences of the residual gravity and the g-jitter under microgravity conditions. A three-dimensional model was employed and calculations were performed by using numerical code named STAR-CD. It is found that the error in diffusion coefficients can be kept to be less than 1 percent when the 1 mm diameter specimen is used. Hence, specimens with diameter less than 1 mm should be selected in order to avoid the effect of gravitational disturbances in the International Space Station., 資料番号: AA0033133017, レポート番号: NASDA-TMR-010019E

半導体溶液中で重力変動によって発生する浮力対流に関し、数値計算による研究を行った。温度差と濃度差に基づく浮力を検討対象とした。残留重力は0gあるいは10(exp -4)gとし、重力変動の振幅は10(exp -4)gあるいは10(exp -3)gとした。重力変動の周波数は10(exp -3)Hzから10Hzとした。重力変動の振幅および周波数が速度、温度、および濃度場に与える影響について検討し、さらに分岐を表す図を作成した。この解析の結果、下記のことがわかった。(1)速度、温度、および濃度の変動は、重力変動の周波数が高いときには小さいが、重力変動の周波数が0.01Hz以下になると大きくなる。(2)重力変動の周波数が小さくなるにつれて、速度、温度、および濃度の変動は正弦曲線から逸脱し、分岐が生じる。(3)濃度変動の振幅は、重力変動が存在しない場合よりは重力変動が存在する場合の方が小さくなる。, Buoyancy convection induced in a semiconductor solution by gravity fluctuations is studied numerically. Buoyancy forces based on the temperature and concentration differences are taken into account. The residual gravity is 0g and 10(exp -4)g, and the amplitude of gravity fluctuation is 10(exp -4)g and 10(exp -3)g. The frequency of gravity fluctuation is changed from 10(exp -3) Hz to 10 Hz. The effects of the amplitude and frequency of gravity fluctuation on the velocity, the temperature and concentration fields were investigated and the bifurcation diagrams are produced. Through this analysis, the following results were obtained: (1) the amplitudes of velocity, temperature and concentration fluctuations are small when the frequency of the gravity fluctuation is high but they become large when the frequency of gravity fluctuation is lower than 0.01 Hz; (2) the fluctuations of velocity, temperature and concentration deviate from sinusoidal curves and bifurcation occurs as the frequency of gravity fluctuation decreases; and (3) the amplitude of concentration fluctuations becomes smaller under residual gravity than in the absence of residual gravity., 資料番号: AA0002208003, レポート番号: NASDA-TMR-990006E

担当教員:喜多 和子･他, 平成25年度(2013)教養コアF(いのちと科学),授業コード:G14F21101

下記の主題について論議した。微小重力、残留加速度、InGaSb、結晶成長、傾斜溶質濃度法、InGaAs、冷却速度、温度勾配、濃度勾配、成長速度、組成的過冷却、残留重力、g-ジッタ、速度変動、温度変動、濃度変動、分岐図、重力変動、濡れ性、表面張力、坩堝、接触角、表面粗度、一方向凝固、熱力学的推進力、格子モデル、過剰エンタルピー、InAs-GaAs系、微分格子パラメータ法、熱力学方程式、成分プロフィル、核形成、種結晶、多成分域溶融法、成長界面、凸型界面、固液界面、境界適合座標法、および熱伝導方程式。, The following subjects were discussed: microgravity, residual acceleration, InGaSb, crystal growth, graded solute concentration, InGaAs, cooling rate, temperature gradient, concentration gradient, growth rate, constitutional supercooling, residual gravity, g-jitter, velocity fluctuation, temperature fluctuation, concentration fluctuation, bifurcation diagram, gravity fluctuation, wettability, surface tension, crucible, contact angle, roughness, directional solidification, thermodynamic driving force, lattice model, excess enthalpy, InAs-GaAs system, differential lattice parameter, thermodynamic equation, composition profile, nucleation, seed crystal, multi-component zone melting, growth interface, convex interface, solid-liquid interface, boundary fitted coordinate, and thermal conduction equation., 資料番号: AA0002208000, レポート番号: NASDA-TMR-990006E

担当教員: 鈴木信夫ほか, 平成22年度(2010)教養コア科目授業F(いのちと科学),授業コード:G14F21101

担当教員: 鈴木信夫ほか, 平成22年度(2010)教養コア科目授業F(いのちと科学),授業コード:G14F21101