Stablization of tahe viscose in the manufacture of artificial fibres

Conclusions A structure and algorithm have been developed for fan adaptive system for stabilizing the composition of viscose in the manufacture of artificial fibres.This system has been introduced into the ACS TP for the manufacture of viscose tire cord at the Svetlogordsk Khimvolokno PO.Translated from Khimicheskie Volokna, No. 5, pp. 25–26, September–October, 1986.     

Damping of bloch oscillations in one-, two-, and three-dimensional quantum-dot superlattices

In the preceding paper by the same authors, the density-matrix formalism was used to derive a quantum kinetic equation describing the damping of Bloch oscillations (BOs) in perfect one-, two-, and three-dimensional quantum-dot superlattices (QDSLs) and the conditions were determined under which the only process of the charge-carrier scattering by phonons in 2D and 3D QDSLs that contributes to the BO damping is the acoustic-phonon scattering within the transverse minibands of the Stark ladder of the carrier states. In this paper, the possibilities of suppressing this remaining scattering channel are analyzed. It is shown that the BO damping time in 2D and 3D QDSLs at room temperature may exceed the oscillation period by a factor of several hundreds and the conditions necessary for such strong suppression of the scattering are revealed. This makes a considerable difference between the QDSLs and the quantum-well superlattices, where, in reality, the BOs damping over a single oscillation period at room temperature.     

The simplest electron-hole complexes localized at longitudinal fluctuations in quantum wires

The variational method is used to study how the states of electron-hole complexes in the quantum wires of a semiconductor are influenced by extra localization along the axis of the structure. Simple trial functions involving a small number of physically substantiated adjustable parameters are suggested, which provides reasonable accuracy in calculating the binding energies of ground states of the complexes in a wide range of parameters of the system. The general form of the trial functions is independent of the specific shape of the irregularity potential. The applicability of the method is demonstrated by the examples of excitons and X ⁺ and X ⁻ trions localized at an irregularity described by a parabolic potential. The error of the method developed here to describe localization of the complexes at arbitrarily shaped potential irregularities is estimated. The accuracy of the variational calculations of the binding energy of localized excitons is estimated by comparing the results with those obtained by direct diagonalization of the Hamiltonian.     

Nonequilibrium population of charge carriers in structures with InGaN deep quantum dots

Electronic and optical properties of ensembles of quantum dots with various energies of activation from the ground-state level to the continuous-spectrum region were studied theoretically and experimentally with the InGaN quantum dots as an example. It is shown that, depending on the activation energy, both the quasi-equilibrium statistic of charge carriers at the levels of quantum dots and nonequilibrium statistic at room temperature are possible. In the latter case, the position of the maximum in the emission spectrum is governed by the value of the demarcation transition: the quantum dots with the transition energy higher than this value feature the quasi-equilibrium population of charge carriers, while the quantum dots with the transition energy lower than the demarcation-transition energy feature the nonequilibrium population. A model based on kinetic equations was used in the theoretical analysis. The key parameters determining the statistic are the parameters of thermal ejection of charge carriers; these parameters depend exponentially on the activation energy. It is shown experimentally that the use of stimulated phase decomposition makes it possible to appreciably increase the activation energy. In this case, the thermal-activation time is found to be much longer than the recombination time for an electron-hole pair, which suppresses the redistribution of charge carriers between the quantum dots and gives rise to the nonequilibrium population. The effect of nonequilibrium population on the luminescent properties of the structures with quantum dots is studied in detail.     

Heat exchange in a plasma chemical reactor with multijet mixing chamber

The article presents the results of the investigation of the heat exchange in a multijet plasma chemical reactor in dependence on the hydrodynamic conditions and design dimensions of the conical mixing chamber.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 1, pp. 128–132, July, 1985.