Temperature dependence of the effective coefficient of Auger recombination in 1.3 μm InAs/GaAs QD lasers

Semiconductor laser heterostructures containing five and ten sheets of InAs/GaAs QDs on GaAs substrates, with an emission wavelength of ～1.3 μm, have been studied. Dependences of the nonradiative lifetime and effective Auger coefficient in QDs are obtained from an analysis of temperature and current dependences of the efficiency of spontaneous radiative recombination. The zero-threshold Auger recombination channel in QDs is shown to dominate at low (below 200 K) temperature, whereas at higher temperatures the quasithreshold channel becomes dominant. The effective 3D Auger coefficient is estimated in the approximation of a spherical QD, and a good agreement with the experimental data is obtained.     

Effect of stationary ionization of traps near the midgap on the spectrum of thermally stimulated capacitance of semiconductor devices

An algorithm for calculating the parameters of deep-level centers in the space-charge region of semiconductor devices on the basis of an analysis of the curves of thermally stimulated capacitance in the presence of recombination centers with the levels located near the midgap is suggested. The method is tested using the commercial AL-107 GaAs-based light-emitting diodes. The results of calculations of the deep-center parameters in the materials under study are consistent with the results of other methods of analysis.     

Error-free 10 Gbit/s transmission using individual Fabry-Perot modes of low-noise quantum-dot laser

A comb-generating laser suitable for DWDM application is demonstrated on the basis of a multimode quantum-dot laser. Bit error rate < 10^-13 at 10 Gbit/s external modulation was measured for 10 longitudinal modes owing to low (<0.3% over 0.001-10 GHz) relative intensity noise of each individual mode.     

Explosion-resistance of the cylindrical part of a fast-reactor vessel

All-Russia Scientific-Research Institute of Electrophysical Apparatus. Special Office of Machine Design. Institute of High Temperatures, Russian Academy of Sciences. Translated from Atomnaya énergiya, Vol. 79, No. 3, pp. 178–188, September, 1995.     

Operating characteristics and their anisotropy in a high-power laser (1.5 W, 300 K) with a quantum-dot active region

Continuous-wave lasing has been demonstrated in a vertically coupled quantum-dot laser with a high output power (1.5 W) at room temperature. It was shown that anisotropy of the quantum dot profile leads to anisotropy of the laser operating characteristics. Pis’ma Zh. Tekh. Fiz. 24, 50–55 (May 12, 1998)     

Thermophysical properties of polyamide yarn-air composite systems

Conclusions By use of methods of nonstationary heat flow, thermophysical characteristics (thermal conductivity, , thermal diffusivity,a, and specific heat capacity, C) have been obtained and the character of the temperature dependence, =f(T), has been established for a yarn-air composite system with a parallel disposition of elementary filaments.The character of the temperature dependence, =f(T), is supported by the results of studies of PA yarn-air composite systems having an unordered disposition of the elementary filaments, which were obtained by the method of a stationary heat flux.The dependence of the change in specific heat capacity coefficient of a composite system with an unordered disposition of elementary filaments on temperature, C = f(T), has been determined by the nonstationary heat flux method.Equations for the temperature dependences of the coefficient of specific heat capacity and the thermal conductivity coefficient of PA complex yarns have been obtained in the temperature range from 300 to 423 K.Translated from Khimicheskie Volokna, No. 4, pp. 46–48, July–August, 1987.     

Production and use of periclase-chromite concrete parts for the linings of high temperature ladles

Conclusions A method has been developed for production of standard periclase-chromite concrete parts for the linings of high temperature ladles for teeming steel and ferroalloys. The parts have high strength and low porosity and are practically shrinkage-free.The life of periclase-chromite concrete parts in the steel teeming ladles of Chelyabinsk Metallurgical Plant is about four times greater than that of fireclay parts, in Red October Plant practically the same as that observed with the use of high alumina parts, and at Chelyabinsk Electrometallurgical Plant it was higher only in the upper portion of ladles in comparison with that obtained with the normally used fired periclase parts.During service in ladles the parts do not spall, become encrusted at a metal temperature of 1620 °C, do not become encrusted at 1790°C, and at 2200°C are eroded by slag.Translated from Ogneupory, No. 7, pp. 16–20, July, 1982.     

Effectiveness and prospectives for making new refractories for heating units in mining-beneficiating combines

Conclusions The East Institute of Refractories (VostIO) has carried out research on the basis of which, taking into account foreign experience, they determined the best compositions for refractory concretes for use in calcination machines for the mining-beneficiation combines; they developed a production method and a repair procedure for linings made of concretes by guncreting.Data on the resistance of these concretes in the linings of OK-306 machines at the Northern Combine (GOK) and two OK-I-520 machines operated at the Mikhailovsk Combine since 1977 indicate that the concretes satisfy modern requirements.The approximate demand for guncrete-concretes recommended for calcination machines by 1985 will be about 25,000 tons. A large proportion of the concretes will be required primarily for conveyer machines and RPO units in which the replacement of presently imported materials by Soviet is now specified.The final decision on the matter of organizing the production of the new materials will be taken by the corresponding planning and economic committees after completion of industrial trials of the concretes in the firing zone of conveyerized and shaft furnaces and in the hearths of agglomeration machines.Translated from Ogneupory, No. 8, pp. 20–25, August, 1981.     

Separation of mixtures and distribution of a liquid on a structured packing in a large-scale model of a distillation column

A large-scale experimental setup is designed to study the hydrodynamic parameters and the mass-transfer efficiency in a countercurrent flow of mixtures of Freon R21 and Freon R114 on structured packings in a column 0.9 m in diameter. The study deals with the local and integral parameters of separation of the mixture, the degrees of nonuniformity of the flow rates and concentration distributions of the liquid and vapor phases over a cross section and on the column wall, and the pressure difference while varying the number of packing layers and their rotation angle. The mass-transfer processes while independently varying the liquid and vapor flow rates over wide ranges are also investigated. Experimental data are presented to illustrate the effect of the operating parameters on the height of an equivalent theoretical plate, the relative pressure difference, and the distributions of the local parameters of the flows.     

Guidance in the main deceleration section during a lunar landing of a spacecraft with an integrated propulsion system

An algorithm is developed for terminal guidance during the main deceleration section of the lunar landing trajectory of a spacecraft with an integrated propulsion system, which has a main engine with variable thrust and four auxiliary nonthrottleable engines. A method of guidance adaptation to the actual motion conditions by measuring the thrust acceleration with jumps in time is proposed.