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141.
Kenji Suzuki Hideaki Yamada Hirofumi Miura Hideaki Takanobu 《Microsystem Technologies》2007,13(8-10):1047-1053
This paper describes three-dimensional microstructures fabricated using a simple self-assembly process involving the thermal shrinkage of polyimide. The proposed method enables hinged structures to be automatically rotated out of the wafer plane and to remain bent without the need to use any interlocking mechanisms. The hinged structures were fabricated using surface micromachining techniques involving heating in a furnace. An increase in the bending angle due to the shrinkage of polyimide was observed with increasing heating temperature, heating time, and length of the polyimide hinge. Of these three parameters, the heating time was found to be the most suitable for precise control of the bending angle. Furthermore, microcubes were fabricated by this method and the self-assembly process was successfully visualized using a CCD camera. 相似文献
142.
Semiconductor injection lasers sometimes reveal excess noise called the mode hopping noise, which is associated with the mode hopping phenomena among longitudinal modes. The mode hopping phenomena are caused by coupling effects among lasing modes. To reduce this kind of noise superposition of high-frequency (HF) current on the injection current is frequently used. This reduction method is theoretically analyzed based on the mode competition theory and is compared with experimental measurements. It is confirmed that the coupling effect among the longitudinal modes is released with the HF superposition because of enhanced vibration of the injected electron, resulting in reduction of the mode hopping noise 相似文献
143.
Yoshihiro Ichikawa Shigeki Obote Kenichi Kagoshima 《Wireless Personal Communications》2005,35(4):353-364
A tapped delayed line adaptive array antenna (TDL-AAA) and a space-temporal simultaneous processing equalizer (ST-SPE) are
proposed as simple space-temporal equalizers based on minimum mean square error (MMSE) criterion. The ST-SPE has a compact
hardware with a small number of taps compared to that of the TDL-AAA. The ST-SPE can reduce the computational complexity of
the space-temporal joint equalization and it works effectively under the minimum phase condition such as appeared at line-of-sight
(LOS) propagation environments at a high antenna height base station. However the ST-SPE cannot work under a non-minimum phase
condition caused under N-LOS (non-line-of-sight). On the other hand, the TDL-AAA whose reference signal is synchronized at
the center tap (TDL-AAAC) can work even in the non-minimum phase condition. In this paper, we propose a dual-mode space-temporal simultaneous processing
equalizer (Dual-mode ST-SPE) which has a simple configuration and also works in non-minimum phase condition. The Dual-mode
ST-SPE can reduce the computational complexity compared to the TDL-AAAC.
Yoshihiro Ichikawa received the B.E. degree in department of communication engineering, in National Defense Academy in 1995, and M.E. and D.E.
degree from Ibaraki University in 2001 and 2004, respectively. He joined the Japan Air Self Defense Force in 1995. His research
interests are an adaptive algorithm, an antenna design, and an adaptive array antenna.
Shigeki Obote received his B.E., M.E. and D.E. degrees in electrical and electronic engineering from Tottori University, Tottori, Japan,
in 1996, 1998 and 2000, respectively. Since 2000, he has been with department of media and telecommunications engineering,
faculty of engineering, Ibaraki University, Ibaraki, Japan, where he is currently a associate professor. His research interests
are in adaptive array antenna and wireless communications systems.
Kenichi Kagoshima received the B.E., M.E. and D.E. degrees in electronics engineering from the Tokyo Institute of Technology, Tokyo, Japan,
in 1969, 1971, and 1974, respectively. He joined the Nippon Telegraph and Telephone Corporation (NTT) Laboratory in 1974 and
researched and developed many kinds of radio communication antennas. Since 1997, he has been a professor at Ibaraki University,
Ibaraki, Japan. Dr. Kagoshima was a Secretary and Treasure, Vice Chairman, and Chairman of the IEEE AP-S Tokyo Chapter in
1992, 1993, and 1994, respectively. He was a chair of antennas and propagation professional group of IEICE in 1999 and 2000.
In 1973, he received the Yonezawa Prize for Young Engineers and 1998, best paper award from IEICE, respectively. 相似文献
144.
Kawahito S. Kameyama M. Higuchi T. Yamada H. 《Solid-State Circuits, IEEE Journal of》1988,23(1):124-132
A 32×32-bit multiplier using multiple-valued current-mode circuits has been fabricated in 2-μm CMOS technology. For the multiplier based on the radix-4 signed-digit number system, 32×32-bit two's complement multiplication can be performed with only three-stage signed-digit full adders using a binary-tree addition scheme. The chip contains about 23600 transistors and the effective multiplier size is about 3.2×5.2 mm2, which is half that of the corresponding binary CMOS multiplier. The multiply time is less than 59 ns. The performance is considered comparable to that of the fastest binary multiplier reported 相似文献
145.
A new receiving planar array antenna for DBS (direct broadcasting satellite) is proposed. The element antenna is a short waveguide aperture mounted in the ground plane, loaded with a dielectric and polarizers, and excited through its side wall by another feeding rectangular waveguide. The gain of the element antenna loaded with a dielectric is so high that the grating lobes can be reduced sufficiently even if the element spacing in the array is wider than the wavelength in free space. Therefore we can reduce the number of the array elements, and parallel feeding by the low loss waveguide network can be feasible to provide a planar array antenna. This paper describes the experimental results of several kinds of the circularly polarized dielectric-loaded element antennas and the planar antennas fed by the waveguide network. In the 12 GHz band the planar antenna with 64-element radiators has a maximum gain of 31.9 dBi with an aperture efficiency of 94.7%, the 1 dB-down frequency bandwidth of the gain is about 800 MHz (6.7% for a center frequency of 11.85 GHz), and the frequency bandwidth of the axial ratio is less than 1 dB of 850 MHz (7.2%) 相似文献
146.
Shigeki Matsunaga 《Polymer Engineering and Science》2019,59(12):2474-2478
Molecular dynamics (MD) simulation of lactic acid (L‐acid) and pyruvic acid (P‐acid) in a physiological salt solution has been performed, which is used as the electrolyte in a sort of biofuel cell working on a human skin. The structure, frequency distribution of molecules, dielectric properties, rotational correlation functions, and diffusion coefficients have been calculated. The anomalous behavior of dielectric constants for the lower concentration of L‐acid and P‐acid has been obtained from MD. The anomalous dielectric constant is discussed in relation with the various physical properties of the solution including the life time of the interaction in the solution. MD results suggest that the anomalous behavior is supposed to be attributed to the difference of interactions between ions in the lower and higher concentration region. POLYM. ENG. SCI., 59:2474–2478, 2019. © 2019 Society of Plastics Engineers 相似文献
147.
A DNA–cyclodextrin–silica composite was prepared by the sol–gel method. This composite possessed the bi-functions of double-stranded DNA, such as intercalation into DNA, and cyclodextrin, such as inclusion into its intramolecular cavity. Therefore, we demonstrated the accumulation of harmful compounds from an aqueous multi-component solution using a DNA–cyclodextrin–silica composite column. As a result, the DNA–cyclodextrin–silica composite column can effectively accumulate not only planar structure-containing harmful compounds, such as dioxin and polychlorobiphenyl (PCB) derivatives, but also non-planar structure containing compounds, such as bisphenol A and diethylstilbestrol, from an aqueous multi-component solution. The accumulated amount of these harmful compounds was more than 90%. Additionally, the DNA–cyclodextrin–silica composite column was recycled by the application of methanol. Therefore, the DNA–cyclodextrin–silica composite may have the potential to be used as an environmental material for the accumulation of harmful compounds from industrial or experimental waste. 相似文献
148.
Hiroyuki Sasakura Yoshiya Akagi Masashi Tanaka Shigeki Tsukui Motoaki Adachi 《Journal of Superconductivity and Novel Magnetism》2012,25(2):305-309
New Pb-based 1222 cuprates containing phosphorus have been synthesized in the (Pb0.75P0.25)Sr2- (RE2–x–y
Ce
x
Sr
y
)Cu2O
z
(RE = Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y) systems. The almost-single phase samples are obtained for 0.5≤x≤1.0 and y=0.1 in the cases of RE = Nd, Dy, Ho, Er, Tm, Yb and Y, while for 0.3≤x≤1.0 and y=0.1 in the cases of RE = Sm, Eu and Gd. The samples crystallize in a tetragonal lattice, the lattice parameters a and c are decreasing with the decrease of the ionic radius of the RE element. Even after annealing under 143 atm O2 atmosphere at 400 °C, almost all the samples with the common values x=0.5 and y=0.1 are semiconductors with a transport process followed by three-dimensional variable range hopping. However, the samples
of RE = Sm, Eu and Gd, which are of almost single 1222 phase, even for x=0.3 and y=0.1, show superconductivity with the onsets at about 25 K, 20 K and 22 K, respectively. Through this study, we find very
important procedure for discovery of new superconducting 1222 compound. 相似文献
149.
Phase transformation and interface segregation behavior in Si3N4 ceramics sintered with La2O3–Lu2O3 mixed additive 下载免费PDF全文
Ryosuke Urakami Yukio Sato Masayoshi Ogushi Takeshi Nishiyama Aoi Goto Kazuhiro Yamada Ryo Teranishi Kenji Kaneko Mikito Kitayama 《Journal of the American Ceramic Society》2017,100(3):1231-1240
Microstructure and mechanical property of silicon nitride (Si3N4) ceramic are strongly dependent on the selection of sintering additives. When rare‐earth (RE) oxide is used as the sintering additive, segregation of RE ions at interface between Si3N4 grain and intergranular glassy film (IGF) is believed to play a critical role. Although the ionic radius of RE ion is known to be an empirical parameter to modify the mechanical property, the correlation between the segregated ions and their ionic radii is still under controversy. In order to address this issue, (i) rate of α‐β phase transformation and (ii) segregation behavior at the interface were studied for Si3N4 ceramics sintered using mixture of La2O3 and Lu2O3 as additives in this study. Specimens of Lu content 30% and higher exhibited lower activation energies for the α‐β phase transformation as compared with those of Lu content 20% and lower. In terms of the segregation behavior, La was preferably segregated at one site and Lu at the other site along β‐Si3N4/IGF interface in the specimens of Lu content 30% and higher. It is understood from these results that Lu segregation site should be more closely related with grain growth. 相似文献
150.