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71.
Okayasu M. Takeshita T. Yamada M. Kogure O. Horiguchi M. Fukuda M. Kozen A. Oe K. Uehara S. 《Electronics letters》1989,25(23):1563-1565
High-power GaInAs strained quantum well lasers with an emission wavelength of 0.98 mu m, suitable for Er/sup 3+/-doped fibre amplifier pumping, have been fabricated. A threshold current of 15 mA and a peak output power as high as 85 mW have been obtained for the ridge waveguide structure with AR/HR facet coating. Highly efficient pumping for the 1.536 mu m signals has been confirmed.<> 相似文献
72.
Hiroshi Aoyama Kohei Tanaka Hiroyuki Watanabe Nobuo Takeda 《Composite Structures》2001,52(3-4):523-531
Transmitted light could detect matrix cracks that occurred in the early stages of fracture of alumina-fiber-reinforced plastics (alumina-FRPs); these cracks could not be detected by acoustic emission (AE). An optical-fiber Bragg grating (FBG) sensor could detect the matrix cracks but it must be embedded in the FRPs. To determine which wavelength is sensitive to the defects in the FRP, the spectra of the transmitted and reflected light were measured. The intensity of the transmitted light, especially in the visible region (wavelength: 400–800 nm), decreased as the bending stiffness of the test piece decreased. It is thus concluded that to monitor the decrease in bending stiffness of FRPs, a simple sensor using a visible ray is good enough. And this transmitted-light NDE technique can work in the strong electromagentic field associated with a superconductor. It will therefore be useful for detecting defects in the FRP of the load-support system in service. 相似文献
73.
Kohei Akaku 《Geothermics》1990,19(5)
The fluids in the Fushime geothermal system, Kyushu, Japan, are hot and saline, and most likely originate from seawater-rock interaction. The type of scale precipitated from the waters differs according to its location in the flow test facilities. Galena and sphalerite are commonly the predominant minerals in the scale coating the insides of the two-phase lines and amorphous silica tends to be dominant in the sections further downstream. Anhydrite has been found to precipitate in a specific zone of a production well where relatively cool sulfate-rich water is believed to mix with ascending hot sulfate-depleted water. 相似文献
74.
Takeshita T. Shibata Y. Ito T. Sakai Y. Okamoto M. Tohmori Y. 《Quantum Electronics, IEEE Journal of》2001,37(12):1636-1642
A laser with a reverse-V-shape layer exhibits a circular beam spot and low threshold current. The beam aspect ratio of the reverse-V-shape laser is clarified to be insensitive to reverse-V-shape width. The reverse-V-shape layer consists of a strained active layer and a passive guide layer, which leads to a low threshold current. The reverse-V-shape laser is attractive as an optical source for optical-communication and information systems 相似文献
75.
Hamada M. Shimizu M. Okayasu M. Takeshita T. Horiguchi M. Tachikawa Y. Sugita E. 《Photonics Technology Letters, IEEE》1990,2(3):205-207
Measured noise characteristics of Er3+-doped optical fiber amplifiers pumped by 0.98- and 1.48-μm laser diodes (LDs) are reported. The noise figures estimated from the beat noise between signal and spontaneous emission are 3.2 dB for pumping by 0.98-μm LD and 4.1 dB for pumping by 1.48-μm LD. The beat noise between spontaneous emission components and the spontaneous shot noise for the 0.98-μm pumping are lower than those for the 1.48-μm pumping 相似文献
76.
Yoshihito Nakagawa Yukihiro Akao Kohei Taniguchi Akemi Kamatani Tomomitsu Tahara Toshiaki Kamano Naoko Nakano Naruomi Komura Hirokazu Ikuno Takafumi Ohmori Yasutaka Jodai Masahiro Miyata Mistuo Nagasaka Tomoyuki Shibata Naoki Ohmiya Ichiro Hirata 《International journal of molecular sciences》2015,16(1):1526-1543
Accumulating data indicates that certain microRNAs (miRNAs or miRs) are differently expressed in samples of tumors and paired non-tumorous samples taken from the same patients with colorectal tumors. We examined the expression of onco-related miRNAs in 131 sporadic exophytic adenomas or early cancers and in 52 sporadic flat elevated adenomas or early cancers to clarify the relationship between the expression of the miRNAs and the endoscopic morphological appearance of the colorectal tumors. The expression levels of miR-143, -145, and -34a were significantly reduced in most of the exophytic tumors compared with those in the flat elevated ones. In type 2 cancers, the miRNA expression profile was very similar to that of the exophytic tumors. The expression levels of miR-7 and -21 were significantly up-regulated in some flat elevated adenomas compared with those in exophytic adenomas. In contrast, in most of the miR-143 and -145 down-regulated cases of the adenoma-carcinoma sequence and in some of the de novo types of carcinoma, the up-regulation of oncogenic miR-7 and/or -21 contributed to the triggering mechanism leading to the carcinogenetic process. These findings indicated that the expression of onco-related miRNA was associated with the morphological appearance of colorectal tumors. 相似文献
77.
Shinya Higashimoto Kohei Okada Tomoki Morisugi Masashi Azuma Hiroyoshi Ohue Tae-Ho Kim Masaya Matsuoka Masakazu Anpo 《Topics in Catalysis》2010,53(7-10):578-583
The photocatalytic oxidation of benzyl alcohol into benzaldehyde proceeded with high conversion and selectivity on a TiO2 photocatalyst by O2 under visible light irradiation. Surface complex formed by the interaction of benzyl alcohol with the Ti sites and/or surface OH groups of TiO2 play an important role in the absorption of visible light and unique selective photocatalytic reaction. 相似文献
78.
Kohei Urasaki Ken-ichiro Endo Tomoki Takahiro Ryuji Kikuchi Toshinori Kojima Shigeo Satokawa 《Topics in Catalysis》2010,53(7-10):707-711
Selective methanation of CO in the reformate gas (CO/CO2/H2/H2O = 0.175/17.9/70.9/11.1) proceeded over Ru catalysts supported on metal oxides and zeolites. CO was selectively methanated at wide temperature ranges (200–275 °C) over Ru/γ-Al2O3, Ru/TiO2 Ru/H-Y and Ru/H-beta catalysts. Higher Ru contents in Ru/γ-Al2O3 improved the selective CO methanation rate. 相似文献
79.
Hidehiro Yoshida Masayasu Kodo Kohei Soga Takahisa Yamamoto 《Journal of the European Ceramic Society》2012,32(12):3103-3114
The sintering behavior of Y2O3 doped with 1 mol% of a trivalent or tetravalent cation was investigated by pressureless sintering in air. Ga3+ or Ge4+-doped Y2O3 bodies exhibited higher relative densities than the undoped Y2O3, while the La3+ or Zr4+-doping suppressed the densification of Y2O3. An interdiffusion experiment was performed on the diffusion couples of polycrystalline Er2O3 and Y2O3 doped with Ni2+ or Zr4+, which are some of the most effective and least effective dopants for the improvement of the sinterability, respectively. The lattice and grain boundary diffusion coefficients of the Er3+ cation in Y2O3 were increased by the Ni2+-doping, but were decreased by the Zr4+-doping. High-resolution transmission electron microscopy observations and nano-probe X-ray energy dispersive spectroscopy analyses confirmed that the dopant cations segregate along the grain boundaries without forming an amorphous phase. The doping effect on the sinterability of Y2O3 must result from the change in the diffusivity in Y2O3. 相似文献
80.
Kazuhiro Yamaguchi Kohei Miyasaka Naoki Kida Yoshio Nogami Syunichi Tada Hideaki Matsue 《通讯和计算机》2013,(10):1350-1359
In this paper, return link systems for wireless mobile camera using 42 GHz-band in multipath fading environments are proposed. The return link systems for wireless mobile camera require wireless transmission with high reliability as same as the conventional wired camera systems. The proposed return link systems achieve transmission with high reliability by taking into consideration frequency and space diversity techniques. The proposed systems can be classified as 3 three types of return link systems according to diversity techniques: FD (frequency diversity) systems, SD (space diversity) systems and FD+SD system (frequency and space diversity). Computer simulations are carried out in order to confirm the effectiveness of the proposed return link systems. It is confirmed that the proposed three types of return link systems have an advantage about BER performances and effectively exploit frequency and space resources. 相似文献