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排序方式: 共有1176条查询结果,搜索用时 21 毫秒
1.
Sh ichi sawa Eiji sawa Yü ji Hirose 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(5):565-585
Initial steps of thermal transformation from doubly bonded [2+2] (1) and [4+4] (2) dimers of C60 have been analyzed on the basis of computed structural features and Pople's energy partition scheme. Completely conjugated C120 structures 3 and 4 are found to be considerably stable and proposed to be important intermediates. The linkage patterns in 3 and 4 are also likely to appear in the repeating units of the metastable dimer and polymer phases of A1 crystals. 相似文献
2.
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
3.
Amorphous specimens of Fe100–x
B
x
were prepared in the range 10 × 35 at % B by a single-roller method. The crystallization process and the boron concentration dependence of the Curie temperature were examined by differential scanning calorimetry, X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. Two-step crystallization was observed in specimens with× < 17: amorphous amorphous + boron-supersaturated b c c phase (-Fe(B)) t-Fe3B +-Fe. A single-Fe(B) phase was not observed. The transition temperature from t-Fe3B to stable (-Fe + t-Fe2B) sensitively depends on the boron content in the alloys. The crystallization temperature (T
x) of the amorphous alloys was almost unchanged for 17 × 31, but increased remarkably at high boron concentrations of× 33, where the decomposition products consisted of t-Fe2B and o-FeB. The Curie temperature (T
c) of the amorphous phase was as low as 480 K at× = 10, increased with increasing boron content up to 820 K and then decreased in the high boron concentration alloys of× > 28. A single-Fe(B) phase was not detected in the as-quenched specimens of× = 8 and 10. The phase coexisted with the o-Fe3B and amorphous phases. The lattice parameter of the phase was 0.28610 nm which was smaller than that of pure iron by 2/1000, indicating the substitutional occupation of boron atoms in the b c c lattice. 相似文献
4.
5.
In membrane filtration, solution environment factors such as pH and solvent density are important in controlling the filtration
rate and the rejection of the particles and/or the macromolecules. The filtration rate and the rejection in membrane filtration
have been investigated from physicochemical aspects. It was shown that the properties of the filter cake formed on the membrane
surface play a vital role in determining the filtration rate in mem-brane filtration. It was clearly demonstrated that such
filtration behaviors as the filtration rate and the rejection are highly dependent on the electrical nature of the particles
and/or the macromolecules. Furthermore, it was shown that the solvent density ρ has a large effect on the steady filtration
rate in upward ultrafiltration. 相似文献
6.
Hai -Hang Li Masafumi Inoue Hiroyuki Nishimura Junya Mizutani Eiji Tsuzuki 《Journal of chemical ecology》1993,19(8):1775-1787
Phenolic compounds have been identified as the most common allelochemicals produced by higher plants. Inhibitions of cinnamic acid, its related phenolic derivatives, and abscisic acid (ABA) on seedling growth and seed germination of lettuce were studied.trans-Cinnamic acid, ando-,m-, andp-coumaric acids inhibited the growth of etiolated seedlings of lettuce at concentrations higher than 10–4 M and seed germination above 10–3 M. Coumarin inhibited seedling growth and seed germination at 10–5 M or above. Chlorogenic acid inhibited seedling growth above 10–4 M, but did not inhibit seed germination at 10–5–5×10–3 M. Low concentrations (below 10–3 M) of caffeic and ferulic acids promoted the elongation of hypocotyls, but higher concentrations (over 10–3 M) inhibited seedling growth and seed germination. These phenolic compounds and abscisic acid had additive inhibitory effects both on seedling growth and seed germination. The inhibition on lettuce was reversed by caffeic and ferulic acids at concentrations lower than 10–3 M except for the inhibition of germination by coumarin. These results suggest that in naturetrans-cinnamic acid,o-, m-, p-coumaric acids, coumarin, and chlorogenic acid inhibit plant growth regardless of their concentration. However, caffeic and ferulic acids can either promote or inhibit plant growth according to their concentration. 相似文献
7.
Takamasa Ishigaki Ya-Li Li Eiji Kataoka 《Journal of the American Ceramic Society》2003,86(9):1456-1463
The phase formation and microstructure of titanium oxides and composites produced by Ar–O2 thermal plasma oxidation of titanium carbide powders were investigated in detail by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Relationships between the phase compositions and microstructures of the oxides were established by combined structural and phase analyses, in correlation with synthesis conditions and phase formation mechanisms. It is revealed that vapor condensation favored the formation of anatase, which existed as smaller particles, while liquid/solid oxidation favored the formation of rutile, which appeared as larger particles or composites. A higher oxygen input in the plasma gases (Ar + O2 ) enhanced the formation of anatase due to impeded oxidation and evaporation. A small amount of Ti4 O7 and Ti3 O5 was detected in the larger particles coexisting with rutile or TiC. These suboxides were formed as intermediates in solid oxidation of TiC or precipitated from the Ti–C–O melt during cooling. Furthermore, extensive cracks, dislocations and stresses were observed in the monolithic rutile and composites, in association with the rapid quenching in this high-temperature in-flight oxidation process. 相似文献
8.
Katsuhiro Inomata Daisuke NakanishiAi Banno Eiji NakanishiYosuke Abe Ryuta KuriharaKentaro Fujimoto Takuhei Nose 《Polymer》2003,44(18):5303-5310
Association behavior and physical gelation mechanism of ABA triblock copolymer dissolved in B-selective solvent have been studied systematically from dilute to moderately concentrated solutions. Static and dynamic light scattering and nuclear magnetic resonance measurements for dilute solutions of poly(methyl methacrylate)-block-poly(tert-butyl acrylate)-block-poly(methyl methacrylate) (PMMA-PtBuA-PMMA) in 1-butanol (PtBuA selective solvent) indicated that PMMA-PtBuA-PMMA chains are molecularly dissolved above 50 °C. With decreasing temperature, the triblock copolymers form associated micelles consisting PMMA associated core and PtBuA shell. Linear dynamic viscoelastic measurements for solutions with moderate concentration (3.9-12.0 wt%) revealed that the system was viscous sol state at 60 °C. Drastic increase of shear storage modulus (G′) occurred with decreasing temperature, and at 25 °C, G′ showed rubbery plateau with weak frequency dependency, means the formation of elastic physical gel. The consistency between the temperature for micelle formation and that at the increase in G′ indicates that the physical gelation is owing to the network formation as the result of the association of PMMA chains and the bridging PtBuA chains connecting the PMMA cores. Master curves for the dynamic moduli were derived by time-temperature superposition along the frequency axis. Just above sol-gel transition concentration (Cgel), the master curves suggest the existence of fairy amount of aggregate that is not incorporated in the macroscopic network. With the increase in polymer concentration, the master curves become to reveal Maxwell-type viscoelasticity with narrow relaxation time distribution, suggesting the formation of transient network with easily generation and destruction of crosslinks. Concentration dependency of the plateau modulus is stronger than the theoretically expected, means the macroscopic transient network grows with polymer concentration by increasing the fraction of elastically effective bridging PtBuA chain above Cgel. 相似文献
9.
Fumitaka Tsukihashi Toshiyuki Hatta Eiji Tawara 《Metallurgical and Materials Transactions B》1996,27(6):967-972
The deoxidation equilibrium of molten titanium and titanium-aluminum alloys saturated with solid CaO has been measured in the temperature range from 1823 to 2023 K. The equilibrium constant of reaction CaO (s)=Ca (mass pct in Ti,Ti-Al)+O (mass pct in Ti,Ti-Al) and the interaction parameter between calcium and oxygen were determined for Ti, TiAl, and TiAl3. The standard Gibbs energy of reaction for TiAl was obtained as follows: $$\Delta G^\circ = 279,000 - 103TJ/mol$$ The possibilities for the deoxidation of titanium and titanium-aluminum alloys by using calcium-based fluxes are discussed. 相似文献
10.
Since the control methods of a transport system between processing machines are specialized for each layout of the system,
it is difficult to design prompt schedules and control logic for new complicated systems, especially in cases of machine faults
or restructuring the system to modify the layout. In this article, we describe a multiagent transport control system which
utilizes pheromone information. Each element of the system acts as an agent and estimates the appropriate path and time to
drive out the products using information obtained by communication with other elements as well as pheromone information deposited
on the tracks of the products. 相似文献