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排序方式: 共有433条查询结果,搜索用时 515 毫秒
101.
Y Kanda S Chiba M Kami T Asai Y Tanaka T Saito Y Yazaki H Hirai 《Canadian Metallurgical Quarterly》1998,100(4):798-800
In thermolysin, tryptophan 115 seems to be at the S2 subsite. Trp-115 was replaced with tyrosine, phenylalanine, leucine, and valine during site-directed mutagenesis in order to evaluate the role of Trp-115 in the proteolytic activity of thermolysin. The mutant enzymes with Tyr-115 or Phe-115 had as much proteolytic activity as the wild-type enzyme, but the other two mutant enzymes had no activity. We found earlier that the substitution of Trp-115 with alanine, glutamic acid, lysine, and glutamine causes the enzyme to lose all activity, so an aromatic amino acid at position 115 seems to be essential for thermolysin. 相似文献
102.
Advanced design techniques for GaAs wideband direct-coupled amplifiers are described. The amplifier achieved a 20 dB gain with a 3 dB bandwidth of 13 GHz and a 5-7 dB noise figure. An equalizing amplifier module consisting of amplifier and variable attenuator monolithic microwave integrated circuits (MMICs) exhibited a high gain of 43 dB over a 10 GHz band with a controllable gain of 20-43 dB 相似文献
103.
Study of meniscus behavior and surface properties during casting in a high-frequency magnetic field 总被引:6,自引:0,他引:6
Tingju Li Shinji Nagaya Kensuke Sassa Shigeo Asai 《Metallurgical and Materials Transactions B》1995,26(2):353-359
Surface quality of continuously cast metals can be improved by imposing a continuous high-frequency magnetic field from the
outside of a mold. Newly proposed concepts of “soft contacting solidification” and “slow cooling solidification,” which is
tightly related to the mechanism of improving surface quality, were confirmed in model experiments by using molten gallium
and tin. The meniscus motion of the molten gallium accompanied by a mold oscillation and magnetic pressure was measured by
a laser level sensor. The shape variation of a meniscus and the process of ripple formation in an oscillation cycle were directly
visualized by an optical fiberscope camera. Moreover, molten tin was continuously cast and the relationship between the surface
quality and the meniscus motion was studied. A mechanical model for predicting the space between the oscillation marks is
proposed. The casting process using intermittent highfrequency magnetic field was developed. New functions of this field were
investigated regarding the control of initial solidification. It was found that the surface quality of the continuously cast
metal can be improved by the intermittent high-frequency magnetic field as well as the continuous high-frequency magnetic
field.
Formerly Undergraduate Student, Department of Materials Processing Engineering, Nagoya University, 相似文献
104.
K Ishimaru K Nishikawa T Omoto I Asai K Yoshihira K Shimomura 《Canadian Metallurgical Quarterly》1995,40(1):279-281
Two new flavone glucosides, 5,2',6'-trihydroxy-6,7,8-trimethoxyflavone 2'-O-glucoside and 5,2',6'-trihydroxy-6,7-dimethoxyflavone 2'-O-glucoside were isolated from the aqueous methanol extract of the roots of Scutellaria baicalensis. From the extract, seven phenolics, 5,7,2',6'-terahydroxyflavone, 5,7,2',5'-tetrahydroxy-8,6'-dimethoxyflavone, skullcapflavone II, baicalin, baicalin methyl ester, wogonin 7-glucuronide and 3,5,7,2',6'-pentahydroxyflavanone were also isolated. 相似文献
105.
Fukawa M. Kawai T. Okano Y. Sakuma S. Asai S. Kanaoka M. Yamanouchi H. 《Power Delivery, IEEE Transactions on》1996,11(2):627-634
500-kV XLPE-insulated cable with an insulation thickness of 27 mm has been developed for long-distance transmission lines. Basic studies on 500-kV XLPE cable have shown that contaminants in the insulation may be the factor determining electrical performance. This hypothesis is justified by the good correlation obtained between statistical estimations of the size of the largest contaminant in the insulation and the electrical characteristics of full-sized cables. Voltage-withstand and long-term tests have confirmed the design values for minimum breakdown stress, for AC and impulse voltage, and for the degradation coefficients 相似文献
106.
A photolithographic technique was developed that uses 1/10-reduction photoprinting with a phase-shifting mask to make gigahertz SAW devices. Combined with a positive-type resist, this new technique produces IDT electrodes with smaller deviations in width compared with using a negative-type resist. Very sharp 40 nm thick AI electrodes with 0.4 μm lines and spaces were achieved. A 2.5 GHz SAW filter suitable for optical communication systems was developed 相似文献
107.
Kenjiro Terada Mitsuteru Asai Michihiro Yamagishi 《International journal for numerical methods in engineering》2003,58(9):1321-1346
We introduce the finite cover method (FCM) as a generalization of the finite element method (FEM) and extend it to analyse the linear and non‐linear mechanical behaviour of heterogeneous solids and structures. The name ‘FCM’ is actually an alias for the manifold method (MM) and the basic idea of the method has already been established for linear analyses of structures with homogeneous materials. After reviewing the concept of physical and mathematical covers for approximating functions in the FCM, we present the formulation for the static equilibrium state of a structure with arbitrary physical boundaries including material interfaces. The problem essentially involves the discontinuities in strains, and possibly has the discontinuities in displacement caused by interfacial debonding or rupture of material interfaces. We simulate such non‐linear mechanical behaviour after presenting simple numerical examples that demonstrate the equivalence between the approximation capabilities of the FCM and those of the FEM. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
108.
A high-speed InGaAs/InAlAs multiple-quantum-well (MQW) intensity modulator and an InGaAsP/InGaAs MQW distributed feedback laser were monolithically integrated by using a hybrid growth technique combining molecular beam epitaxy and metalorganic vapor phase epitaxy. An operating drive voltage of only 2.0 V, a 20-dB on/off ratio, and a 3-dB bandwidth greater than 15 GHz were obtained. This device operated stably in a single mode and with a side-mode suppression ratio of more than 50 dB 相似文献
109.
Kenichi Asai 《New Generation Computing》2002,20(1):27-51
This paper presents a specializer and a binding-time analyzer for a functional language where expressions are allowed to be
used as both static and dynamic. With both static and dynamic expressions, data structures can be statically accessed while
they are residualized at the same time. Previously, such data structures were treated as completely dynamic, which prevented
their components from being accessed statically. The technique presented in this paper effectively allows data structures
to be lifted which was prohibited in the conventional partial evaluators. The binding-time analysis is formalized as a type
system and the solution is obtained by solving constraints generated by the type system. We prove the correctness of the constraint
solving algorithm and show that the algorithm runs efficiently in almost linear time.
Kenichi Asai, Ph.D.: He is a research associate at the Department of Computer Science, Faculty of Science, the University of Tokyo. He obtained
his bachelors degree, masters degree, and doctor of Science from the University of Tokyo in 1990, 1992, and 1997, respectively.
His research interests are in Programming Languages in general, in Partial Evaluation and Reflection in particular. He is
a member of ACM, IPSJ, and JSSST. 相似文献
110.
Dynamically-Stable Motion Planning for Humanoid Robots 总被引:9,自引:0,他引:9
James J. Kuffner Jr. Satoshi Kagami Koichi Nishiwaki Masayuki Inaba Hirochika Inoue 《Autonomous Robots》2002,12(1):105-118
We present an approach to path planning for humanoid robots that computes dynamically-stable, collision-free trajectories from full-body posture goals. Given a geometric model of the environment and a statically-stable desired posture, we search the configuration space of the robot for a collision-free path that simultaneously satisfies dynamic balance constraints. We adapt existing randomized path planning techniques by imposing balance constraints on incremental search motions in order to maintain the overall dynamic stability of the final path. A dynamics filtering function that constrains the ZMP (zero moment point) trajectory is used as a post-processing step to transform statically-stable, collision-free paths into dynamically-stable, collision-free trajectories for the entire body. Although we have focused our experiments on biped robots with a humanoid shape, the method generally applies to any robot subject to balance constraints (legged or not). The algorithm is presented along with computed examples using both simulated and real humanoid robots. 相似文献