Kuniaki Miura

Hifi VCR System

Improvement of the sound quality for home VCRs has been strongly desired. As the tape velocity becomes smaller according to the high density recording, the conventional fixed sound head gives poor quality in S/N and frequency response. It is well known that the sound quality is greatly improved by recording the sound signal with rotary heads. Using this concept, FM sound multiplex recording system has been developed and standardized in the 8mm VCR system in March 1983. 1), 2)

New Video Doc System with Miniaturized Low Frequency Saw Device in Home VTR

A new dropout compensation system with miniaturized low frequency SAW device has been developed, corresponding with the stream of high density magnetic recording.

Numerical Simulation of Cavitation for Comparison of Sodium and Water Flows

In this paper, numerical simulation of cavitation for water and sodium flows were performed by using CFD code package FLUENT and the results were compared with the experiments. The geometry of the grid for numerical calculation was a venturi with ID and OD of 6.5 and 21 mm, respectively. The numerical simulations showed that the onset cavitation conditions were affected significantly by the non-condensable gas content in the liquid. Comparing with the experimental results, the non-condensable gas contents that gave close predictions of onset cavitation conditions with the experiments were larger in water than in liquid sodium because of the different solubility property of air and argon gas. Parametrical analysis showed that the void fraction distributions for water and liquid sodium did not show large differences in case of the same caviation coefficient and non-condensable gas contents.Copyright

Characteristics of Cavitation and Erosion Phenomena in Sodium Flow

This paper presents experimental data of cavitation experiments to determine the characteristics of cavitation and erosion in the flowing liquid sodium at 200–400°C. The test section is a venturi made from SUS316 since this material is used as the cladding material for SFR. The ID and OD of the venturi test section are 6.5 mm and 21.4 mm, respectively. The data show that the onset cavitation conditions (onset velocities) in liquid sodium are influenced by the change of the stagnant pressure at the expansion tank. Cavitation noise signals at developed cavitation conditions are not affected by the change of stagnant pressure and might be caused by choking of the sodium flow that restricts the formation of cavitation bubbles. For all the different stagnant pressures and temperatures, the onset cavitation coefficient K is around unity. Meanwhile, erosion experiment in the flowing liquid sodium for 600 hours at 200°C and cavitation coefficient value K of 0.59–0.51 (developed cavitation condition) reveals that cavity bubbles produce some micro pits at the outlet of the venturi test section. These pits indicate that erosion is occurred on the surface of the tested material and could be a major problem for the development of SFR if cavitation occurs inside the critical/important parts.Copyright

New Miniaturized SAW Device in Low Frequency Range for SAW Video DOC System in Home VTR

A new dropout compensation method called the SAW video DOC system has been developed, corresponding to the stream of high density magnetic recording. The purpose is to improve the signal-to-noise ratio and the characteristic of dropout compensation for the palyback signal in home video tape recorders. A wide band SAW device in low frequency range of the key device in the system is miniaturized and practically can-packaged by newly developed techniques: the reduction of finger pairs, new ultraviolet curable polymeric resin and suppression of undesired wave response. In consequence, almost complete dropout compensatin and improvement of the 2.5 dB signal-to-noise ratio can be achieved in a playback video signal.