The Development of Intelligent Beamforming Antenna Systems for Stratospheric Platforms in the Millimeter-Wave Band

In this paper, we describe intelligent beamforming antenna systems that can be used in the millimeter-wave band for High-altitude platform systems. We have developed two antenna systems for the millimeter-wave band and have designed experiments to test the efficiency of the developed systems. One is a multi-beam-horn antenna that enables high-speed transmission, and the other is an array antenna that digitally controls antenna beams. These antenna systems are also designed to work in the stratosphere. We also describe our solutions to the problems of low temperature and low pressure and show that the two antenna systems can function well in the stratosphere through tests conducted on the ground.On April 1, 2004, the Communications Research Laboratory (CRL) and the Telecommunications Advancement Organization of Japan (TAO) merged to create NICT.Hiroyuki Tsuji received the B.S., M.S., and Ph.D. degrees from Keio University in 1987, 1989, and 1992, respectively. Since 1992, he has been working in the Communications Research Laboratory, Independent Administrative Institution, Japan. In 1999, he was a visiting researcher at University of Minnesota. He is now a senior researcher of Wireless Innovation Systems Group in the Yokosuka Radio Communications Research Center of NICT (National Institute on Information and Communications Technology, reorganized from CRL in April 2004). His research interests are in array signal processing, particularly as applied to communications. He received the IEICE 1996 Young Engineer Award. He is a member of IEICE and IEEE.Masayuki Oodo was born in Osaka, Japan, on February 1, 1969. He received B.E., M.E. and D.E. degrees in Electrical and Electronic Engineering from Tokyo Institute of Technology, Tokyo, Japan in 1992, 1994 and 1997, respectively. In 1997, he joined the Communications Research Laboratory (CRL, now part of the National Institute of Information and Communications Technology, or NICT), where he has been researching array antennas for wireless communication and frequency-sharing issues between HAPS and other systems. Dr. Oodo received the Paper Presentation Award from IEICE Japan in 1995, the Young Scientist Award from URSI in 1996, the Young Engineer Award from IEICE Japan in 1997, and the Young Engineer Award from IEEE AP-S, Tokyo Chapter in 1998. He is a member of IEEE.Ryu Miura received the B.E., M.E., and PhD degrees in Electrical Engineering from Yokohama National University, Yokohama, Japan, in 1982, 1984, and 2000, respectively. He joined Communications Research Lab (CRL), Ministry of Posts and Telecommunications, Tokyo, Japan in 1984, where he worked for research on mobile satellite communication systems using the Engineering Test Satellite, ETS-V. During 1991–1992, he was a visiting researcher in AUSSAT, Pty. Ltd. (now Optus, Pty. Ltd.), Sydney, Australia. During 1993–1996, he was a senior researcher in ATR Optical and Radio Communications Research Labs, Kyoto, Japan, where he worked for research on digital beamforming antennas for mobile communications. He is now a group leader of Wireless Innovation Systems Group in the Yokosuka Radio Communications Research Center of NICT (National Institute on Information and Communications Technology, reorganized from CRL in April 2004), where he works for R&D on wireless communication systems using stratospheric platforms. Dr. Miura is a member of IEEE and IEICE.Mikio Suzuki received a B.S. degree in electronic engineering from Keio University in 1970. He joined Mitsubishi Electric Corporation in 1970, where he researched and developed microwave integrated circuits and waveguide array antennas for defense radars and missiles. He is now at the NICT Yokosuka Stratospheric Platform Research Center, and his current research interests lie in the system design of applications for wireless communication systems using a stratospheric platform and the development of related communication equipment. He is a member of the IEICE of Japan.     

Non-slip-type restoring force characteristics of an exposed-type column base

This paper describes an experimental study on exposed-type column bases with new restoring force characteristics. Generally, an exposed-type column base consists of elastic/plastic anchor bolts and an elastic thick base plate. The restoring force characteristics of these column bases are observed to be slip-type due to the gap between the nut of the anchor bolt and the base plate, caused by the plastic elongation of the anchor bolt. These restoring force characteristics can be governed by elastic/plastic anchor bolts, an elastic/plastic base plate and/or a gap between the nut and the base plate. In particular, the gap between the nut and the base plate can be eliminated by means of a new device consisting of a wedge compressed by a spring and a counter-wedge. To show the fundamental characteristics of the new column base, two kinds of specimens were tested. The conclusions obtained are as follows. (1) The cyclic characteristics of conventional column bases with elastic/plastic anchor bolts and an elastic base plate became slip-type. (2) The cyclic characteristics of column bases with the gap between nut and base plate eliminated by use of the device became non-slip-type, that is, linear from the origin at each loading step.     

Development of ZnSe‐based white light emitting diodes with longer lifetimes of over 10,000 hr

We have demonstrated ZnSe‐based white light emitting diodes (LEDs) with longer lifetimes of over 10,000 hr at 14.5A/cm² by introducing an i‐ZnMgBeSe/p‐ZnMgSe double cladding structure, which includes a very thin i‐ZnMgBeSe layer for suppressing electron overflow and a p‐ZnMgSSe layer for efficient p‐type carrier concentration. By adopting the double cladding layer instead of only the conventional p‐ZnMgSSe cladding layer, rapid degradation is suppressed and the lifetime tendency becomes similar to that of the LEDs consisting of a III‐V semiconductor system. The device simulation and the temperature dependence of optical power showed that the i‐ZnMgBeSe layer played the main role in increasing electron confinement. Our experimental data and reliability test results indicate that the suppression of the electron overflow is essential to achieve a long lifetime acceptable for practical use. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 154(4): 42–48, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20285     

Form and function of arterial bifurcations in various parts of the animal body

Branching patterns of arterial networks might influence vascular resistance and allow control of blood supply to peripheral tissues. Arterial casts from the brain, kidneys, and earlobes of cats and the chorioallantoic arteries of chick embryos were used for microscopic measurements of arterial geometry. From the measured diameters of parent and two daughter vessels at arterial bifurcations, we calculated the diameter exponent m. By applying the minimum work concept to blood flow through a cylindrical vessel, an optimal value m = 3 has been derived (Murray’s cubic law). The measured values of the diameter exponent were 2.59, 2.54, 2.58, and 2.49 for the brain, kidneys, earlobes, and chick embryos, respectively, exhibiting significant deviation from Murray’s law. The physiological implication of the m values is discussed here.     

Intracellular proteins of ethanol-treated yeast cells involved in iron sorption

Iron is essential for human health, but it sometimes causes an unpleasant taste, rusty colour and a decrease in the stability of food products. Previously, we found that ethanol-treated yeast (ETY) cells could remove iron from wine and juice, and reduce the fishy aftertaste induced by iron in wine–seafood pairings. However, the mechanism of iron sorption by ETY cells is undefined; thus, there is no indicator that can be used to estimate the iron sorption capacity of these cells. In this study, we showed that cell wall components are not mainly associated with iron sorption by investigating ETY cells with the cell wall removed. Moreover, plasma membrane permeability was correlated with the iron sorbing capacity of the cells. Microscopic analysis showed that iron accumulated within ETY cells. Proteinase-treated ETY cells had no iron sorbing capacity. On the basis of these results, we conclude that intracellular proteins are involved in iron sorption by ETY cells.     

City-level energy and CO2 reduction effect by introducing new residential water heaters

Simulation models for a variety of new water heater systems were developed and the models were integrated into a city-level residential energy end-use model for Osaka City. Using the model, the potential of energy conservation and CO₂ emission-reduction by introducing new residential water heaters was evaluated at the city-level. Optimal water-heating systems for each household category for primary energy reduction, CO₂ emission-reduction, or cost reduction were identified by applying the end-use demand model. The effect of subsidies for installing more efficient systems and the influence of diffusion of these systems on electricity load curves were also discussed.     

Flow stress analysis for determining the critical condition of dynamic ferrite transformation in 6Ni–0.1C steel

In order to clarify the occurrence of dynamic ferrite transformation in a 6Ni–0.1C steel, the stress–strain behavior in uniaxial compression was analyzed for a wide range of temperatures and strain rates. Significant softening of flow stress for austenite was observed at lower temperatures at a constant strain rate, which seemed to correspond with the occurrence of dynamic transformation to ferrite. Analysis of the maximum stress in the stress–strain curves indicated that dynamic ferrite transformation occurred above a certain value of the Zener–Hollomon parameter (Z). The critical deformation condition (Z_C) for the occurrence of dynamic transformation was determined. Increasing the amount of softening resulted in an increase in the fraction of ferrite, and the maximum flow stress came close to the flow stress of ferrite. Microstructural observations revealed that the specimens exhibiting softening consisted of ferrite grains with typical characteristics of deformation microstructure, such as a change in crystal orientation within the ferrite grain, inhomogeneity in ferrite morphology and dislocation substructures inside the grains. All these characteristics confirmed the occurrence of ferrite transformation during deformation, i.e. dynamic ferrite transformation.     

Statistical analysis of lightning surges on distribution lines based on the observation

Probability distribution of surge discharging current of arresters provided a basis for conventional theory of grounding systems. In order to rationalize the grounding systems, it is necessary to grasp the statistical data of lightning surges on distribution lines caused by direct lightning strokes and indirect lightning strokes. Lightning phenomena on TEPCO's distribution lines had been continuously observed for the rationalization of lightning protection design of distribution lines. The observation had been carried out with still cameras and monitoring sensors of lightning surges. This makes it possible to discover new interesting facts that can be useful for rationalization of lightning protection design of distribution lines. Cumulative frequency distribution of conventional data is close to that of ZnO discharging current in the case of direct strokes and indirect strokes through TEPCO's observation. Moreover, to verify the cumulative current distribution in concrete poles, the authors have compared the cumulative distribution of current through ground lines with that of current through ground lines and concrete poles. The results show that the distribution of current through ground lines and concrete poles is larger than that of current through only ground lines for high currents exceeding 1 kA. This fact suggests that lightning surge current flows not only in ground lines but also in concrete poles. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 36–44, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20468     

Estimating stochastic volatility models of stock returns in Chinese markets

Volatility plays a key role in microstructure issues in the study of financial markets. Stochastic volatility (SV) models have been applied to the study of the behavior of financial variables. Two stock markets exist in China: Shanghai Stock Exchange and Shenzhen Stock Exchange. As emerging stock markets, investors are increasingly concerned about the volatilities of these two stock markets. We briefly introduce how to estimate SV models using the Markov chain Monte Carlo (MCMC) method. In order to do full and comprehensive analyses of the volatilities of stock returns, we estimated SV models using most of the historical data and the different data frequencies of the two Chinese markets. We found that estimated values of volatility parameters are very high for all data frequencies. This suggests that stock returns are extremely volatile even at long-term intervals in Chinese markets.