Chiba Institute of Technology

About: Chiba Institute of Technology is a education organization based out in Narashino, Japan. It is known for research contribution in the topics: RNA & Magnet. The organization has 2663 authors who have published 4999 publications receiving 56870 citations. The organization is also known as: Chiba kōgyō daigaku & Kōa Institute of Technology.

Shock-induced silicate vaporization: The role of electrons

Abstract: [1] We conducted a spectroscopic study of shock-heated silicate (diopside) and obtained the time evolution of the spectral contents, the line widths of emission lines, and the time- and irradiance-averaged peak shock temperatures. The peak shock pressures ranged from 330 to 760 GPa. Time-resolved emission spectra indicated that the initial spectrum was blackbody radiation; the spectrum evolved to yield several ionic emission lines, which in turn evolved to yield atomic lines at the later stages. The shock-heated diopside was highly dissociated and ionized, even though it is likely to have been subjected to high-pressure conditions near the liquid–vapor phase boundary. The time evolution of the spectra, from ions to atoms, strongly suggests that electron recombination occurred in the expanding shock-induced diopside vapor. The time- and irradiance-averaged peak shock temperatures at >330 GPa were lower than the theoretical Hugoniot curve, with a constant isochoric specific heat, indicating endothermic shock-induced ionization. Thus, we conclude that electrons behave as an important energy reservoir in energy partitioning via endothermic shock-induced ionization and subsequent exothermic electron recombination. This electron behavior leads to a higher degree of vaporization after isentropic release and a lower cooling rate due to the exothermic electron recombination in expanding impact-induced silicate vapors than previously expected. These results will affect the predictions associated with hypervelocity impact events in planetary science, such as the origin of the Moon and chemical reactions and production of silicate dust particles in impact-generated silicate vapor clouds.

The characteristics of single crystal bismuth wires produced by the Ohno continuous casting process

Abstract: Bismuth wires approximately 2 mm in diameter were produced by the heated mould Ohno Continuous Casting process and their mechanical characteristics evaluated. It was found that cast wires produced under all speed conditions from 30 to 170 mm min−1 were single crystals. Cast wires with an angle between the cleavage plane and wire axis of less than about 40° were significantly more ductile than those with an angle of over 57°. The former could be bent repeatedly before fracture occurred whereas the latter fractured after only a single bend. It was also found that the bismuth wires with a cleavage angle of less than 45°, exhibited tensile elongations up to about 130%.

Shock compression response of forsterite above 250 GPa

Abstract: Forsterite (Mg2SiO4) is one of the major planetary materials, and its behavior under extreme conditions is important to understand the interior structure of large planets, such as super-Earths, and large-scale planetary impact events. Previous shock compression measurements of forsterite indicate that it may melt below 200 GPa, but these measurements did not go beyond 200 GPa. We report the shock response of forsterite above ~250 GPa, obtained using the laser shock wave technique. We simultaneously measured the Hugoniot and temperature of shocked forsterite and interpreted the results to suggest the following: (i) incongruent crystallization of MgO at 271 to 285 GPa, (ii) phase transition of MgO at 285 to 344 GPa, and (iii) remelting above ~470 to 500 GPa. These exothermic and endothermic reactions are seen to occur under extreme conditions of pressure and temperature. They indicate complex structural and chemical changes in the system MgO-SiO2 at extreme pressures and temperatures and will affect the way we understand the interior processes of large rocky planets as well as material transformation by impacts in the formation of planetary systems.

Straight and circular road driving control of power assisted wheelchair based on balanced assisted torque

Abstract: This paper describes a straight and circular road driving control scheme for power assisted wheelchair. Power assisted wheelchair which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of the straight and circular road driving must be further improved because the two wheels are driven independently. This paper proposes a straight and circular road driving control scheme based on the balanced assisted torque between the two wheels. The balanced assisted torque is determined from the proportion of the human input torque to the right and left wheels. Some experiments and subjective evaluation show the effectiveness of the proposed control system.