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This paper proposes a new type of motion base for virtual sensation of acceleration by applying a parallel cable drive architecture. It has outstanding advantages in comparison with conventional Stewart platforms. Especially, 1) rotational motion range is large; 2) the motion platform can be grounded on the floor; 3) scene projection to all the walls is possible; and 4) its redundancy of cables improves safety for cut of cables. Optimal fundamental mechanical design is performed from the viewpoint of kinematics. Simulation results show that a 3-3-2 cable configuration is one of the best designs as a motion base. The prototype developed has the maximum motion range of translation ±0.45 m × ±0.4 m × 1.1 m and that of rotation ±45° in roll angle, ±45° in pitch, and ±35° in yaw. It can produce acceleration 1 G for 0.8 s at its maximum, even if gravity is not used. A trajectory planning method for longer-term sensation utilizing gravity is proposed. Low-frequency component of acceleration is realized by rotational motion and high frequency is produced by translational motion. Experimental results to create virtual acceleration of a roller coaster demonstrated effectiveness of this new design [ABSTRACT FROM PUBLISHER]

The kinetics of the reduction of interstitial oxygen (Oi) due to the formation of thermal double donors (TDDs) upon heat treatment in an oxygen-rich Ge crystal were investigated at various temperatures. Specimens were prepared from a Ge crystal with oxygen at a concentration of 4-5 × 1017 cm-3 grown by a new Czochralski method and were heat-treated in the temperature range 300-500 °C. Shrinkage of a dissolved oxygen absorption peak at 855 cm-1 and simultaneous development of a thermal double donor peak at 780 cm-1 were observed by infrared absorption spectroscopy at room temperature. The formation of TDDs was also detected electrically. Reduction of dissolved oxygen concentration upon the heat treatments was kinetically analyzed. The activation energy of the reduction of Oi concentration was evaluated to be 1.7 and 2.0 eV in the early and prolonged stages of the heat treatment, respectively, close to that of Oi diffusion. From the results, TDD development process was indicated to be the merge reaction of Oi-Oi to form oxygen dimers (Odimer) in the early stage of the heat treatment and further enlargement of Odimer to TDDs by absorbing Oi in the prolonged stage of the heat treatment in accordance with the On-2NN model. [ABSTRACT FROM AUTHOR]