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11.
Komukai T. Yamamoto T. Sugawa T. Miyajima Y. 《Quantum Electronics, IEEE Journal of》1995,31(11):1880-1889
A 1.064-μm band upconversion pumped Tm3+-doped fluoride fiber amplifier and a laser both operating at 1.47 μm are investigated in detail. The two devices are based on the 3F 4→3H4 transition in a trivalent thulium ion, which is a self-terminating system. When pumped at 1.064 μm, the amplifier has a gain of over 10 dB from 1.44 to 1.51 μm and a low-noise characteristic. Also, the fiber laser generates a high-output power of over 100 mW with a slope efficiency of 59% at around 1.47 μm. These levels of performance will be important for optical communication systems 相似文献
12.
Miyajima H. Asaoka N. Arima M. Minamoto Y. Murakami K. Tokuda K. Matsumoto K. 《Journal of microelectromechanical systems》2001,10(3):418-424
This paper presents a moving-coil electromagnetic optical scanner with newly developed hinge structure consisting of multilayered polyimide films with aluminum lead wires in between. The main purpose is to obtain a scanner with good durability and shock resistance for practical use. Polyimide has both features, and the aluminum lead wires, connecting the moving-coils and fixed electrode pads, are more reliable, because they are located inside the hinge, where the stress caused by torsional deformation and atmospheric degradation are minimal. An electromagnetic actuator is used to satisfy the following requirements; a millimeter-sized mirror, resonant and galvanometric operation, and scan angle control. Scanner prototypes with two different specifications (i.e., fast scanner and slow scanner) were fabricated and characterized. Driven with a sinusoidal current of ±20 mA, the fast scanner and the slow one vibrated with an optical scan angle (&thetas;o) of 1° at the resonant frequency (fr) of 1.7 kHz and &thetas;o of 60° at fr of 72 Hz, respectively. Durability was demonstrated with a shock test of 2500 G and a life test of over 13 000 h. By substituting sputtered aluminum driving coil with electroplated copper coil, improved &thetas;o of 16.8° was obtained at fr of 2.7 kHz 相似文献
13.
Numerical Evaluation of Toughening by Crack-Face Grain Interlocking in Self-Reinforced Ceramics 总被引:1,自引:0,他引:1
Serguei Kovalev Tatsuya Miyajima Yukihiko Yamauchi Mototsugu Sakai 《Journal of the American Ceramic Society》2000,83(4):817-824
Crack bridging associated with the pull-out process of interlocking grains in self-reinforced ceramic materials is studied through a micromechanical simulation. The pullout of a single inclined grain is modeled via the numerical solution of a general contact problem. The bridging-force versus crack-opening-distance curve indicates a nonlinear, springlike response for the pullout of interlocking grains. The sliding friction along the debonded interface, induced by highly localized contact stresses, dominates the total bridging force. The bridging force increases with grain inclination until eventual bridge failure. The pullout of misaligned grains mainly affects short-crack toughening, with a rising R -curve, whereas aligned grains contribute to long-crack toughening. The residual stresses of the thermal expansion anisotropy play a minor role in the pull-out process of grain interlocking and the resultant toughening. The proposed mechanism is operative in both single-phase and composite ceramics in which pullout of elongated grains/reinforcements occurs. 相似文献
14.
The thickness-fringe method [Ishida et al., Philosophical Magazine 42 (1980) 453] for complete determination of the character of a dislocation Burgers vector has been performed in CaIrO3 perovskite and post-perovskite deformed at high pressures and high temperatures. By selecting several main zone axes and determining the number of terminating thickness fringes at the extremity of a dislocation from a wedge-shaped thin-foil specimen in weak-beam dark-field transmission electron microscope (TEM) images, the Burgers vectors were unambiguously determined. The results demonstrate that [1 0 0] screw and edge dislocations on the (0 1 0) slip plane are dominant in the post-perovskite phase. Curved [1 0 0] and [0 1 0] dislocations and straight 〈1 1 0〉 screw dislocations on a potential (0 0 1) slip plane were identified in the perovskite phase as well as a high density of {1 1 0} twins. Low-angle tilt boundaries consisting of different groups of parallel edge dislocations on the {1 1 0} and (0 0 1) planes indicate diffusion-assisted climb in perovskite at high temperatures. The differences in dislocation microstructures could be due to activations of limited numbers of slip systems for post-perovskite and of a large number of multiple slip systems for perovskite, which may result in the strong crystallographic preferred orientation (CPO) in post-perovskite and the lack of CPO in deformed perovskite. 相似文献
15.
The failure properties of high-strength fiber splices following proof tests are studied experimentally and theoretically. It is clarified that splice strength can be improved by conducting proof tests and that the strength distribution and the time-to-failure after a proof test can be predicted theoretically. Taking into account the applicability of these results for submarine optical-fiber cables, it is necessary to conduct a proof-test ofsigma_{p} = 2.5 -percent strain on fiber-splicing points. 相似文献
16.
T. Tago Y. Shibata T. Hatsuta K. Miyajima M. Kishida S. Tashiro K. Wakabayashi 《Journal of Materials Science》2002,37(5):977-982
Silica (SiO2)-coated rhodium (Rh) nanoparticles were prepared using a water-in-oil microemulsion of polyoxyethylene (15) cetyl ether, cyclohexane and water. SiO2-coated Rh nanoparticles were obtained by hydrolyzing metal alkoxide (tetraethylorthosilicate, TEOS) in the solution containing Rh complex nanoparticles followed by thermal and reduction treatments. In the SiO2-coated Rh nanoparticle, a Rh particle with an average diameter of 4.1 nm was located nearly at the center of each spherical SiO2 particle. The SiO2 layer was approximately 15 nm thick. Since the Rh particle was wholly surrounded by SiO2, the Rh particle of the SiO2-coated Rh nanoparticle exhibited an extremely high thermal stability. Furthermore, the porous structure of the SiO2 layer could be controlled by the hydrolysis conditions of TEOS. 相似文献
17.
The amplification characteristics at around 1.5 μm of a 0.9-m-long, 1000-p.p.m Er3+-doped single-mode fluoride fiber are discussed. By using 1.48-μm laser diodes with 55-mW launched output as a pump source, a gain of 1.75 dB was obtained at 1.530 μm. A broad bandwidth of 40 nm was obtained, which may be suitable for wavelength-division multiplexing (WDM) system use 相似文献
18.
A. Bozbey S. Miyajima T. Ortlepp A. Fujimaki 《Journal of Superconductivity and Novel Magnetism》2011,24(1-2):1065-1069
In this study, we report on our simulation and experimental results for quasi-one junction SQUIDs (QOS) comparator targeted to be used in the front-end of the detector read-out circuits. The QOS is used as a 1-bit quantizer in the front-end of the read-out circuit. Their performance and reliability is very much depending on the circuit parameters of the QOSs. The main design parameters are the threshold level, gray zone width, and the chip-to-chip reproducibility over different fabrication batches. For some special applications, such as detector readout, the overall power consumption needs to be sufficient small. We measured threshold and gray zone counting each individual switching event for various bias and input current values and for different QOS designs. In addition, circuit simulations including thermal noise are used to explain the observed circuit behavior and to optimize design parameters. 相似文献
19.
A method has been developed for the identification of unknown brighteners in detergents by a high-performance liquid chromatography
(HPLC)/mass spectrometry (MS)/ultraviolet (UV)/fluorescence system with MS/MS capability. Ten brighteners from five groups—stilbene,
biphenyl stilbene, pyrazoline, oxazole, and coumarin derivatives—were separated on a C8 reverse-phase HPLC column. The UV and fluorescence detectors positively located the brightener peaks and differentiated betweentrans andcis isomers separated by the chromatographic system. Ion-spray (IS)/MS and IS/MS/MS spectra were then used to identify the structure
of unknown brighteners in detergent products. An HPLC with a diode-array detector provided a quick identification check and
accurate quantitative data for known brighteners, even on overlapping peaks. 相似文献
20.
K Hattori T Hirano C Ushiyama H Miyajima N Yamakawa T Ebata Y Wada S Ikeda K Yoshino M Tateno K Oshimi N Kayagaki H Yagita K Okumura 《Canadian Metallurgical Quarterly》1997,90(2):542-548
Tumor necrosis factor (TNF) and Fas ligand (FasL) have been implicated in the pathogenesis of graft-versus-host disease (GVHD), which is a major complication after allogeneic bone marrow transplantation. We examined here the ameliorating effect of a metalloproteinase inhibitor (KB-R7785) that inhibits TNF-alpha and FasL release in a lethal acute GVHD model in mice. Administration of KB-R7785 into (BALB/c x C57BL/6) F1 that received C57BL/6 spleen cells markedly reduced the mortality and weight loss in association with minimal signs of GVHD pathology in the liver, intestine, and hematopoietic tissues. The ameliorating effect of KB-R7785 was superior to that of anti-TNF-alpha antibody. Our results suggest that KB-R7785 could be a potent therapeutic agent for GVHD. 相似文献