In this paper, the authors discuss the rudder roll control system (RRCS) which was newly developed. The model of the RRCS is based on the multivariate auto regressive model which has been fitted by ...the minimum AIC method to the actual time series records including yaw, roll rate and rudder motions. The feedback gains not only to keep the required course but also to reduce roll motion are given by statistical optimization technique. The salient feature of the RRCS is that a designer does not need any preliminary information about the dynamical properties of the ship except for the yaw, the roll rate and the rudder motions driven by random steering during her navigating. After feasible study and simulations of the rudder roll stabilization using the actual record, the results of full scale experiments at sea are reported.
Thermal Properties of HIP Sintered Silicon Nitride WATARI, Koji; SEKI, Yoshiyuki; ISHIZAKI, Kozo
Journal of the Ceramic Society of Japan,
1989/01/01, 1989-00-00, Letnik:
97, Številka:
1121
Journal Article
Odprti dostop
Thermal diffusivity and conductivity as well as specific heat were studied for capsule-HIP sintered Si3N4. Yttria and alumina additives with a total amount of 6mol% were used. For a given additive ...percentage, specimens of higher β phase fraction had higher thermal diffusivity and conductivity, as expected However, samples with larger amounts of Y2O3 additive had higher thermal diffusivity and conductivity in spite of a lower β phase fraction than those with more Al2O3 additive. The highest thermal conductivity was 70W/(m·K) with 6mol% Y2O3 additive alone. The reason is that aluminium and oxygen ions are soluble in β-Si3N4 particles, in the case for Al2O3 addition. Oxygen, presented as an impurity, also had a profound effect on the thermal diffusivity and conductivity. Higher oxygen contents reduced the thermal diffusivity and conductivity. This may be due to the amount of grain boundary glassy phase. The specific heat of sintered Si3N4 was 0.67±0.02kJ/(K·g). The crystalline structure (α or β-Si3N4), additive composition, and raw material particle size did not show any effect on the specific heat.
Thermal diffusivity and conductivity as well as specific heat of capsule-HIPped Si3N4 with Y2O3 and Al2O3 6mol% in total as additives were measured at different temperatures ranging from 100 to ...1300K. The isobaric specific heat Cp agreed with the isochoric specific heat Cv calculated by the Debye's theory, assuming that silicon and nitrogen atoms are lattice dynamically equivalent. The Dulong-Petit's rule applied well to sintered Si3N4 at high temperatures and Cv≅25J/(K·mol). The glassy phase quantity could be estimated by the difference of the measured specific heat and the calculated specific heat at low temperatures. The specimens with higher thermal diffusivity and conductivity at low temperatures were those with higher β-phase fraction, larger particle size of raw Si3N4 and richer Y2O3 additive. For these specimens the thermal diffusivity and conductivity showed a larger temperature depencence.
In Japan, televised broadcasts of First Generation Enhanced Television (EDTV-I) began in August 1989. The Telecommunications Technology Council is currently investigating improvements for a second ...phase of Enhanced Television (EDTV-II). This document describes the present status of EDTV-I and the trends in development of EDTV-II in Japan.
2-6 Trends of International Standardization Seki, Yoshiyuki
The Journal of the Institute of Television Engineers of Japan,
1988/07/20, Letnik:
42, Številka:
7
Journal Article
A digital broadcasting system for satellites operating in the 12.5 GHz band has been standardized by the Japanese Telecommunication Technology Council. For the maximum commonality and ...interoperability of the system with other delivery media, the digital broadcasting system uses technologies based on the internationl standards or recommendation for source and channel coding systems. While for the conditional access system. an original system is adopted to meet service requirements in Japan. This paper introduces outlines of the system, as well as remaining issues to be solved.
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