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81.
The paper proposes a new approach to estimate the lower bounds of critical loads for circular cylindrical shells. These bounds
are compared with the ordinary lower bound of critical load under which a shell with initial deflections loses stability.
The lower bound produced by the approach is higher than the ordinary bound and can be used in design
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 10, pp. 78–85, October 2006. 相似文献
82.
Physical principles, design and operation characteristics of a negative mass cyclotron resonance maser inp-type germanium are considered in this paper. The formation of anisotropic inverted distributions of negative effective mass heavy holes in strong electric and magnetic fieldsE H [001], resulting in negative conductivity in the millimetre and submillimetre wavelength ranges, is discussed. The generation is observed at 0.9 to 8mm in low compensated germanium samples with the hole concentration rangeN
0 2×1012 to 2×1014 cm–3 at low temperaturesT 25 K in electric fieldsE 40 to 350Vcm–1. The maser frequency is tuned by the magnetic field corresponding to a cyclotron resonance frequency of carriers with an effective mass ofm
c 0.4m
0. The spectral width of the emission in single mode operation does not exceed several megahertz. A pulse duration of 1 to 200 s and a repetition rate off
rep 1 to 200 Hz has been obtained limited by sample heating. Possibilities of improving the maser characteristics inp-Ge as well as in other AIII Bv semiconductors and the perspectives of new frequency tuning methods due to the application of uniaxial stress and magnetic field are demonstrated. 相似文献
83.
84.
G. R. Kosmambetova P. E. Strizhak K. S. Gavrilenko V. I. Gritsenko 《Theoretical and Experimental Chemistry》2006,42(5):308-313
The catalytic characteristics of systems prepared by mechanically mixing iron oxide nanoparticles, produced in the thermolysis
of carboxylate complexes at 300–750°C, with aluminum oxide in the oxidation of CO were studied. It was shown that increase
in the size of the iron oxide nanoparticles leads to decrease in the catalytic activity of the samples as a result of their
different structural and textural characteristics, which change in relation to the synthesis conditions.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 300–305, September–October, 2006. 相似文献
85.
V. A. Yakovlev I. F. Gavrilenko G. N. Bondarenko O. V. Chausova 《Polymer Science Series B》2006,48(4):203-205
The suspension polymerization of butadiene in hexane and toluene in the presence of catalysts composed of organoaluminum compounds and neodymium versatate applied on oxides (Al2O3, aluminum silicate A-14, Aerosil A-300, and white soot BS-200) has been studied. Triisobutylaluminum and its combination with ethylaluminum sesquichloride are used as organoaluminum compounds. The activity and stereospecificity of the catalysts has been found to depend strongly on the nature of supports. Catalysts based on Aerosil and white soot appear to be the most active. With the use of these catalysts, polybutadiene containing up to 97.5% 1,4-cis-units has been synthesized. 相似文献
86.
Photoelectric characteristics of materials Pb1-xSnxTe?In? subject to microwave and infrared emission
Yu. A. Abrahamian V. I. Gavrilenko Z. F. Krasylnick V. V. Nickonorov K. Z. Papazian S. L. Smirnov V. I. Stafeyev 《International Journal of Infrared and Millimeter Waves》1993,14(8):1667-1678
Current/voltage (CV) characteristics of solid solutions Pb1–xSnxTeln (with D. 22x3. 24 and 0.2NIn1.0 atomic percent) were studied at He temperatures, in presence of background at 300K. Also the photoconductivity of these materials was measured in conditions of background screening and illumination at wavelengths 100µm and 2mm.CV-characteristics are interpreted within a model of two-electron capturing by Jahn-Teller centers. Photoconductivity in millimeter and submillimeter wavebands, having relaxation times less than 10–5 sec, is related with heating of electronic gas in process of electromagnetic power absorption by the free carriers. 相似文献
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