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排序方式: 共有4044条查询结果,搜索用时 15 毫秒
31.
32.
Eiji Hoashi Takehiko Yokomine Tomoaki Kunugi 《International Journal of Heat and Mass Transfer》2003,46(21):4083-4095
This paper presents a numerical simulation of wave-type heat transfer phenomena propagating in an aluminum thin foil irradiated by a pulsed laser using the cubic interpolated propagation method coupled with a thermo-convective model. We did not use the two-step model and dual-phase lag model, which are generally known as the non-Fourier heat conduction law, but wave-type heat transfer phenomena could be observed by our method. The main characteristic of the method is to solve the governing equation including the equation of continuity, the equation of motion, the equation of energy and the equation of state. It is found that when the pulse duration is under the order of picosecond, the pure heat conduction is hardly observed and heat transfer toward the inside of materials occurs only by a thermal shock wave. The heat conduction mode after pulse laser irradiation is strongly dependent upon the value of total incident laser energy density Ein and the threshold value for pure heat conduction is 5.0 × 104 J/m2 for an aluminum. 相似文献
33.
Keiji Itabashi Takuji Ikeda Akihiko Matsumoto Kunikazu Kamioka Masanao Kato Kazuo Tsutsumi 《Microporous and mesoporous materials》2008,114(1-3):495-506
Four types of Rb-aluminosilicate zeolites were hydrothermally synthesized in pure phase for the first time from Rb-aluminosilicate gels without using any organic structure-directing agent (SDA) under stirring conditions. The crystal structure of each zeolite was refined by Rietveld analysis of the X-ray diffraction (XRD) data. These crystal structures were confirmed to be Rb-mordenite, Rb-merlinoite, a new aluminosilicate zeolite with an ATT framework topology, and Rb-offretite denoted by RMA-1, RMA-2, RMA-3, and RMA-4, respectively. The Si/Al ratio of RMA-1 with an MOR topology varied from 5.3 to 8.0; however, the variation of the Si/Al ratios of the other zeolites was rather small. The crystal system of RMA-2 was tetragonal with space group I4/mmm, where two Rb sites were distributed at the center of an 8-membered ring (MR). On the other hand, two Rb sites in RMA-3 were located at the center of the 8-MR in small two cages. The structure of RMA-4 was identified as the OFF type with a local disorder or defect, which included a small amount of an intergrown ERI phase. 相似文献
34.
Kazuhiko Honda Eiji ૿ sawa Zdenek Slanina Takatoshi Matsumoto 《Fullerenes, Nanotubes and Carbon Nanostructures》1996,4(5):819-834
As a continuation of the studies on thermal transformation of the [2+2] C60 dimer (1), the consequence of the pyracylene-rearrangement-like valence isomerization of the fulvalene partial structure at the bridge of the ring-opened product from 1, namely 2, was searched by dynamic reaction coordinate /AM1 semiempirical MO calculations. It is predicted that the fulvalene bridge of 2 rearranges into naphthalene partial structure by the concerted 'in-plane' mechanism to give a wide-bridged C120 intermediate having twenty five-membered rings and two ten-membered rings (3). The computed energy of activation (145 kcal/mol) is 40 kcal/mol lower than those computed for pyracylene rearrangements. In contrast, the recently reported analogous rearrangement of indigo (13) to dibenzonaphthyridindione (14) is computed to occur by the stepwise 'sp3' mechanism. 相似文献
35.
T. Shimada M. Mizuno K. Kurachi N. Kato O. Sakurada M. Hashiba Y. Nurishi 《Journal of Materials Science》1996,31(14):3691-3695
Low thermal expansion coefficient and high mechanical strength have been attained simultaneously in a composite with microstructures in which the low thermal expansion grains are surrounded by a continuous texture of the grains with high strength. Alloying eucryptite with yttria-stabilized PSZ (partially stabilized zirconia) simultaneously achieved the low thermal expansion coefficient, 1.45 × 10–6, and the high bending strength, 220 MPa, by adjusting the composition and controlling the microstructures by changing the starting powders and the milling durations. Grain size and reactions between the coupled materials determined the critical processing conditions. 相似文献
36.
Serum rheumatoid factor (RF) level and peritoneal and splenic CD5+B (B-1) cells in mice were examined after intraperitoneal administration of purified lipopoly-saccharides (LPS) from oral periodontopathic bacteria; Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum and Capnocytophaga ochracea. F. nucleatum and C. ochracea LPS induced higher levels of serum IgM- and IgG-RF, while P. gingivalis LPS showed the least induction. In addition, wet weights of spleen and serum IgM and IgG concentration were markedly increased in F. nucleatum LPS injected group. On the other hand, the proportion of CD5+ B cells to lymphocytes in the peritoneal cavity and spleen did not increase. The reason for this was not clear but conventional B cells (CD5- B cells) might increase more rapidly with splenic enlargement than CD5+ B cells. These results suggested that RF induced by bacterial LPS may modulate immune responses against bacteria and plays an important role for defence and destruction of periodontal tissue. 相似文献
37.
Manabu Ishitobi Takeshi Myoi Koji Soshin Eiji Hiraki Mutsuo Nakaoka 《Electrical Engineering in Japan》2005,153(3):79-87
This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126 相似文献
38.
S Suzuki M Saito N Suzuki H Kato N Nagaoka S Yoshitake Y Yui C Kawai 《Canadian Metallurgical Quarterly》1993,22(6):834-840
We examined the thrombolytic properties of a novel modified human tissue plasminogen activator (PA) (E6010), in which cysteine 84 is replaced by serine, and which has a prolonged biologic half-life (t1/2). We compared the thrombolytic efficacy of continuous intracoronary (i.c.) infusion of E6010 with that of recombinant human tissue PA (rt-PA) in a canine model with copper coil-induced 1-h-old coronary artery thrombi and also compared the relation between thrombolytic efficacy and plasma clearance represented by pharmacokinetic parameters of i.c.-infused E6010 and rt-PA. Sixty-minute E6010 and rt-PA i.c. infusions were compared. The thrombolytic effects of i.c.-infused E6010 and rt-PA, represented by time to reperfusion (TR), reperfusion rate at 60 min (RR), and reocclusion rates at 60 min after reperfusion (OR) were as follows. E6010: Dose 0.06, 0.15, 0.3 (mg/kg/h); TR 25 +/- 10, 15 +/- 10, 13 +/- 5 (min); RR 100, 100, 100 (%); and OR 0, 0, 17 (%), respectively. Recombinant t-PA: Dose 0.06, 0.15, 0.3 (mg/kg/h); TR 47 +/- 12, 18 +/- 17, 14 +/- 4 (min); RR 50, 75, 100 (%); and OR 100, 33, 33 (%), respectively. These findings indicate that E6010 has more potent thrombolytic activity than rt-PA.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
39.
We developed a noble technique for the fine-particle handling in plasmas. In this method a pair of point electrodes are introduced in the plasma, to which positive pulses are applied alternatively. When the pulse repetition period is shorter than the particle response time, the particles feel only time-averaged force because of their large mass. Spatial profile of the equivalent potential of the time-averaged force varies from a circle to an ellipse with an increase in the local discharge at the electrodes. The particles are eventually transported toward a middle point between two point-electrodes, being almost independent of their initial positions. This method is quite effective for converging fine particles in the plasma. 相似文献
40.
Kubota S. Dobashi A. Suzuki M. Hasumi T. Kato S. 《Vehicular Technology, IEEE Transactions on》1997,46(1):108-113
In personal communication systems, better voice quality and lower terminal price are essential requirements, and adaptive differential pulse-code modulation (ADPCM) codecs are one of the voice codec candidates that have good voice quality and reasonable cost. However, in slow fading environments, burst errors induce click noise in ADPCM voice signal transmission. This paper proposes a novel error-concealment scheme to improve the ADPCM voice signal transmission quality of time division multiple access time division duplex (TDMA-TDD) personal communication systems in slow fading environments. The proposed scheme employs an improved error-detection technique with PCM differential detection and overflow detection coupled with a cyclic redundancy check (CRC) code. To compensate for residual click noise, an expanded CRC error-detection signal is used. Erroneous PCM signals are adaptively suppressed according to the click-noise detection information. Hardware simulation results show that these techniques significantly improve ADPCM voice signal transmission quality by 0.5 points and 1.0 compared to that of the conventional ADPCM muting scheme and no processing, respectively, with the mean opinion scoring (MOS) test in the slow fading environments typical of personal communication systems 相似文献