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891.
L. Ya. Karachinsky T. Kettler N. Yu. Gordeev I. I. Novikov M. V. Maximov Yu. M. Shernyakov N. V. Kryzhanovskaya A. E. Zhukov E. S. Semenova A. P. Vasil’ev V. M. Ustinov N. N. Ledentsov A. R. Kovsh V. A. Shchukin S. S. Mikhrin A. Lochmann O. Schulz L. Reissmann D. Bimberg 《Semiconductors》2005,39(12):1415-1419
Lasers based on InAs/InGaAs quantum dots grown on metamorphic (In,Ga,Al)As layers deposited by MBE on GaAs substrates exhibited emission near 1.5 μm with a differential quantum efficiency of about 50%. The narrow-stripe lasers operate in a single transverse mode and withstand continuous current density above 20 kA cm?2 without significant degradation. A maximum continuous-wave output power of 220 mW is obtained. Neither current nor beam filamentation was observed up to the highest pumping levels. 相似文献
892.
The convexity and continuity of fuzzy mappings are defined through a linear ordering and a metric on the set of fuzzy numbers. The local-global minimum property of real-valued convex functions is extended to convex fuzzy mappings. It is proved that a strict local minimizer of a quasiconvex fuzzy mapping is also a strict global minimizer. Characterizations for convex fuzzy mappings and quasiconvex fuzzy mappings are given. In addition, the Weirstrass theorem is extended from real-valued functions to fuzzy mappings. 相似文献
893.
N. N. Belov Yu. A. Biryukov A. T. Roslyak N. T. Yugov S. A. Afanas’eva 《Theoretical Foundations of Chemical Engineering》2005,39(3):307-312
A new circulation pneumatic crusher capable of producing submicron powders of refractory materials is presented. A mathematical model is constructed for the dynamic breaking of ceramic macroparticles. This model allows the basic laws of shock-wave crushing in the circulation pneumatic apparatus to be analyzed.__________Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 3, 2005, pp. 327–333.Original Russian Text Copyright © 2005 by Belov, Biryukov, Roslyak, Yugov, Afanas’ev. 相似文献
894.
V.L. Varentsov V.L. Ryabov V.V. Yaschuk S.N. Andrianov A.A. Matyshev 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,228(2-3):343-348
A focusing magnetic resonance system (MRS) with a new type of supersonic atomic - and molecular - beam source is suggested. The beam sources used in the MRS are discussed and the main operation principles of the suggested supersonic beam source as well as the advantages of this type of source over the rest are shown. An optimization procedure for the magnetic resonance system with the effect of the finite source size taken into account is considered. Numerical results are given and analyzed. The MRS with the new type of beam source possesses higher transmission with low background and is simpler and cheeper in construction as compared to the conventional systems. 相似文献
895.
The composition of the Co-Cr-Mo alloy has been modified by additions of nickel and some trace elements aluminium, titanium and boron. In this paper, the first part of the present study, the effects of alloy additions on the microstructures and tensile properties of the as-cast Co-Cr-Mo alloy are discussed. The effects of alloy additions on the fatigue behaviour of the alloy will be discussed in the second part of the present study. It is found that alloy additions do not seem to result in changes in the nature of the casting structure. A directional, coarse dendritic cast structure is produced in the modified alloys as in the base alloY. However, the alloy additions affect the carbide precipitations and the formation of some fine details of the microstructure such as dislocations, stacking faults and twins produced during the solidification. A considerable improvement in the transient mechanical properties, especially in the tensile ductility, is achieved by modifying the base alloy with alloy additions. 相似文献
896.
P. Papet N. Le Bars J. F. Baumard A. Lecomte A. Dauger 《Journal of Materials Science》1989,24(11):3850-3854
Transparent yttria-stabilized zirconia monolithic gels were synthesized under controlled conditions for hydrolysis and chemical polymerization. The influence of acetylacetone on the previous chemical reactions was explored, and a plausible explanation was proposed concerning the outstanding role of this additive during the gelation process. Small-angle X-ray scattering was used to estimate the size of the polymeric species and to investigate the influence of acetylacetone on the structure of the gels prepared. 相似文献
897.
898.
Translated from Izmeritel'naya Tekhnika, No. 6, pp. 19–20, June, 1989. 相似文献
899.
900.
The change in polystyrene (PS) layer thickness, which has been simultaneously determined during post-yield deformation, shows
that crazing is the basic mechanism of toughening in all laminated films, and that shear deformation supplements the contribution
of crazing especially for samples with high polyethylene (PE) volume fractions. Crazes formed in PS layers in the laminated
films are slender and regular compared with the short and lenticular crazes formed in bulk PS film. When PE volume fraction
increased, craze advance speed decreased because of the reduction of the stress concentration effect at craze tips. The life-time
of the first mature craze to be formed at a given strain rate increased with PE volume fraction because the PE supporting
the mature crazes could effectively inhibit craze rupture and blunt out the propagating crack by absorbing the stored elastic
energy in the PS layer that would have been dissipated as fracture surface energy. 相似文献