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41.
SHAO Jun Shanghai University of Science Technology Shanghai ChinaXU Hua CHEN Nianyi Shanghai Institute of Metallurgy Academia Sinica Shanghai China SHAO Jun Associate Professor Dept.of Chemistry Shanghai University of Science Technology Shanghai China 《金属学报(英文版)》1990,3(10):221-225
The structure and properties of molten salt solution o J Li,K|F,Cl system have been investigedby computerized simulation of molecular dynamic method.The partial RDF,the partial molarenergy of mixing and the diffusion coeffients of Li~+,K~+,F~- and Cl~- have been calculated.The results are in agreement with the experimental values.The regularities of the distributionof ions and mieroscopic holes are discussed based on the results of computerized simulation. 相似文献
42.
F. H. Spedding A. H. Daane K. W. Herrmann 《JOM Journal of the Minerals, Metals and Materials Society》1957,9(7):895-897
The electrical resistivities of high purity lanthanum, cerium, praseodymium, and neodymium were investigated as a function of temperature over the range from room temperature to near the melting points of the metals. Transformation temperatures were observed in these metals which were confirmed by supplementary X-ray diffraction studies. 相似文献
43.
We report here for the first time, on the comparative studies of the photophysical and optical limiting behavior of our two novel phthalocyanines namely 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyanines 2, and 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyaninato zinc (II) (3) in solution and thin films. Nonlinear optical (NLO) properties of the samples in solution and contained in polysulfone (PSU) thin films were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. Effects of aggregation and disaggregation on the NLO performance of metal-free phthalocyanine are reported in detail. Our findings showed that the prepared Pcs show larger nonlinear absorption coefficient and lower limiting thresholds when embedded in polysulfone films compared to in solutions. The values of nonlinear susceptibility and hyperpolarizability recorded for 3-PSU in this work are respectively, ∼2.09 × 10−8 esu and ∼1.02 × 10−26 esu. These values are among the largest values reported for phthalocyanines and other macrocycles doped on polymer matrices. 相似文献
44.
J. L. Tallon C. Bernhard Ch. Niedermayer J. Shimoyama S. Hahakura K. Yamaura Z. Hiroi M. Takano K. Kishio 《Journal of Low Temperature Physics》1996,105(5-6):1379-1384
We show from muon spin relaxation (SR) studies on mercury HTS superconductors that a 50-fold increase in irreversibility field obtained by partial substitution of Re for Hg is due to metallisation of the Hg/Re layer. Induced superconductivity on this metallic layer doubles the overall superfluid density. This suggests a new approach to the design of high performance HTS materials: metallising one of the non-CuO2 interlayers and thereby greatly enhancing the superconducting properties. 相似文献
45.
Ricardo Soto Hakan Kjellerstrand Orlando Durán Broderick Crawford Eric Monfroy Fernando Paredes 《Expert systems with applications》2012,39(13):11423-11427
Cell formation consists in organizing a plant as a set of cells, each of them containing machines that process similar types or families of parts. The idea is to minimize the part flow among cells in order to reduce costs and increase productivity. The literature presents different approaches devoted to solve this problem, which are mainly based on mathematical programming and on evolutionary computing. Mathematical programming can guarantee a global optimal solution, however at a higher computational cost than an evolutionary algorithm, which can assure a good enough optimum in a fixed amount of time. In this paper, we model and solve this problem by using state-of-the-art constraint programming (CP) techniques and Boolean satisfiability (SAT) technology. We present different experimental results that demonstrate the efficiency of the proposed optimization models. Indeed, CP and SAT implementations are able to reach the global optima in all tested instances and in competitive runtime. 相似文献
46.
《Electric Power Systems Research》2006,76(5):293-301
This work proposes a methodology to generalize the Y-connections for 12- and 18-pulse autotransformers. A single mathematical expression, obtained through simple trigonometric operations, represents all the connections. The proposed methodology allows choosing any ratio between the input and the output voltages. The converters can operate either as step-up or as step-down voltage. To simplify the design of the windings, graphics are generated to calculate the turn-ratio and the polarity of each secondary winding, with respect to the primary winding. A design example, followed by digital simulations, illustrates the presented steps. Experimental results of two prototypes (12 and 18 pulses) are presented. The results also show that high power factor is an inherent characteristic of multi-pulse converters, without any active or passive power factor pre-regulators needs. 相似文献
47.
Silica-embedded nanocrystalline TiO2 powders were synthesized by sol-hydrothermal process. The influence of the composition of the solvent and the embedded silica
content on the phase transition, grain growth and subsequently, on the photoactivity of TiO2 were investigated. The volume ratio of ethanol to water for the solvent composition was varied from 0.125 to 8 and the mole
fraction of silica content was changed from 0 to 0.4, while the condition for hydrothermal reaction was fixed at 250∘C for 2 hour. With an increase in ethanol content in solvent composition, the crystallite sizes of pure TiO2 particles decreased from 15 nm to 6 nm and crystal phase changed from rutile/anatase mixed phase to pure anatase phase.
Addition of silica to TiO2 brought about an increase in the photocatalytic activity by suppressing the phase transition from anatase to rutile. Judging
from the result of the decomposition of 1, 4-dichlorobenzene, the most efficient catalyst was found to be 0.2 mole fraction
SiO2 embedded TiO2 prepared with ethanol-rich solvent (the volume ratio of ethanol to water is 4). 相似文献
48.
采用香兰素法合成药物中间体3,4,5-三甲氧基苯甲醛,总收率为71%.以香兰素为原料,采用溴素为溴代试剂制备5-溴香兰素,收率达96%以上.甲氧基化反应以氯化亚铜作为催化剂,DMF为溶剂,甲醇钠为甲氧基化试剂制得丁香醛,收率为90%.以碳酸二甲酯为甲基化试剂使丁香醛发生甲基化反应制得3,4,5-三甲氧基苯甲醛,收率为82%. 相似文献
49.
《Materials Research Bulletin》2006,41(5):1015-1021
Thermochromic VO2 nanorods were prepared via thermal conversion of the metastable VO2–B phase synthesized by hydrothermal methods. We observe an increased thermochromic transition temperature to ∼75–80 °C by variable-temperature infrared spectroscopy. Nano- and sub-micron structures of other vanadium oxides (V3O7, (NH4)0.5V2O5, and V2O5) were obtained simply by varying the starting materials in the hydrothermal synthesis. We also obtained nanostructures of the high temperature tetragonal rutile phase of VO2 by thermolysis of single-source vanadium (IV) precursors. 相似文献
50.
《Materials Letters》2005,59(24-25):3054-3058
Fluoride-substituted hydroxyapatite (FHAp) nanorods have been successfully prepared by adding Tween80. As compared to the spheroidal morphology without any surfactant, the FHAp nanorods prepared with Tween80 were elongated along the c-axis. The reason was attributable to the enlarged difference between the growth rates of crystal surfaces due to the adsorption of Tween80. The effects of the pH value on the apatite formation were investigated by calculating the solubility isotherms of the Ca2+–PO43−–F−–H2O system in conjunction with experimental results, and it was found that acidic solutions were unfavorable to FHAp preparation and the proper pH should be controlled at about 9 when preparing the FHAp nanorods with the addition of Tween80. 相似文献