The frequency of an AlGaAs semiconductor laser was stabilized by using the linear absorption spectrum of the 85Rb-D2 line. By controlling the injection current, the frequency stability of 3.0×10-10≧σ≧1.4×10-12 was obtained for 10 ms≦τ≦500 s. First observation of the saturated absorption spectrum of the 85Rb-D2 line is demonstrated, which can be used as a frequency reference to improve the frequency stability.
A new robot that makes use of MR-fluid clutches for simulating torque is proposed to provide an appropriate device for training physical therapy students in knee-joint rehabilitation. The feeling of torque provided by the robot is expected to correspond to the torque performance obtained by physical therapy experts in a clinical setting. The torque required for knee-joint rehabilitation, which is a function of the rotational angle and the rotational angular velocity of a knee movement, is modeled using a mechanical system composed of typical spring-mass-damper elements. The robot consists of two MR-fluid clutches, two induction motors, and a feedback control system. In the torque experiments, output torque is controlled using the spring and damper coefficients separately. The values of these coefficients are determined experimentally. The experimental results show that the robot would be suitable for training physical therapy students to experience similar torque feelings as needed in a clinical situation.
Diamond powders are used for polishing electronics devices such as hard disk substrates. The surface profile of the polished texture affects the final properties of hard disk and so polishing materials and polishing process are very important. Polishing materials have to be dispersed homogeneously without aggregation. Many dispersants are then developed to improve the dispersion property of polishing materials, whereas improvement of the surface properties of polishing materials using dispersant is not essential. In this study, an attempt was made to modi@ the surface of diamond powders using acoustic cavitation generated by irradiation of strong ultrasonic wave on aqueous diamond slurry. As a result, the diamond particle surface was verified to be modified by the oxidizing action of active oxygen species formed by acoustic cavitation.
IEEE ULTRASONICS SYMPOSIUM-431 0-7803-7177-
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