Microstructure and Orientation of TiSi2Layers on (111) Si

The microstructure and orientation of TiSi₂films produced by pulsed illumination of Ti layers on (111) Si with incoherent light and by vacuum evaporation of Ti onto heated (111) Si substrates were studied by transmission electron microscopy. Both theC49- and C54-TiSi₂grains were found to have a number of orientations satisfying the basic crystallographic rules: a high density of coinciding sites at the interface and continuity of high-density planes across the interface. The TiSi₂/Si interfaces studied were shown to be incoherent. The major structural defects in TiSi₂layers were identified.     

Application of MIMO technology in wideband millimeter range wireless communications systems

A concept of using MIMO technology in millimeter range wireless communications systems with orthogonal frequency division multiplexing is considered. The concept is based on dividing transmitting and receiving multi-element antenna arrays into separate sub-arrays with analogue radiation pattern shaping and on using two most powerful space sub-channels for information transmission. Sequence and structure of transmitted packets between transceivers are suggested that allow for obtaining information on communications channel based on additional training sequences without feedback channel. Modeling results of communications system’s operation in conditions of multipath frequency-selective fading channel are presented.     

Factors in Phase Formation in the Heterogeneous Chain Oxidation of Dichlorosilane at Low Pressures

Dichlorosilane oxidation, a heterogeneous branching-chain reaction, is considered in terms of unsteady-state nucleation theory taking into account the condensation growth of nuclei, and the following observations are interpreted: the crossover between the homogeneous and heterogeneous phase formation; the dependence of the amount of aerosol on the initial temperature, pressure, and admixture concentration; and the kinetics of phase formation and of the disappearance of the original substance. Introducing an inhibitor is found to reduce the mean size of aerosol particles. This result is in qualitative agreement with experimental data. It is found that it is because of the growing equilibrium vapor pressure of the new phase that the amount of aerosol formed decreases with increasing initial temperature, including when an active admixture is present. The reactivity of the silicon dioxide aerosol obtained in the presence of Freon-12 varies reversibly. The role of surface diffusion and surface nucleation in the deposition of thin films is discussed.     

Self-propagating chain combustion with formation of ultradispersed powders

We have investigated the possibility of realizing the self-propagating combustion regime for a gaseous mixture of SiH₄–NH₃–O₂ and SiH₄-2 with an oxygen content of 0–2%. Calculation of the equilibrium composition indicates the possibility that the target products Si and Si₃N₄ are formed. We have established experimentally that propagation of the chemical reaction front in the self-sustaining regime with formation of the above-indicated products occurs only in the presence of oxygen. We show that chemical induction, leading to consumption of up to 60% of the initial monosilane, is a chain reaction.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka 142432. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 4, pp. 85–91, July–August, 1994.     

A physical model of an induction electric heater for cryogenic control devices

A physical model of an induction electric heater for cryogenic control devices has been proposed. The chosen method of research has been justified. The scheme of the model, the structure of the measuring equipment, and a research technique that determines the energy characteristics of the induction heater have been considered, and recommendations on its design have been made. It is shown that it is advisable to use a three-leg laminated core with the winding located in the middle core as a basic element. Such a structure of the induction heater allows one to carry out research varying the material and shapes of the heated object. A microprocessor measuring complex that allows one to control and record up to six electric signals with an error no higher than 2% has been proposed.     

On the use of fuzzy logic in control systems for technological equipment

The possibilities and prospects of using fuzzy logic in control systems for electro-technological equipment are analyzed based on a comparative study of standard temperature controllers of resistance furnaces and fuzzy logic controllers. It is shown that it is effective to use fuzzy logic control systems for different kinds of technological equipment. The development of fuzzy logic control systems and characteristics of their application are analyzed. The basic structures of systems constructed using fuzzy logic control are considered, is the way in which they are classified. The simulation models of temperature controllers for resistance furnaces are studied using the Matlab/Simulink software including the Fuzzy Logic Toolbox application. It is shown that a use of fuzzy controllers for simple deterministic control systems like temperature controllers of resistance furnaces does not lead to any substantial improvement in accuracy and control quality, but needs a sophisticated algorithm for control and response speed of the control system. It is assumed that a use of fuzzy logic controllers to control more sophisticated equipment characterized by the multifactor processes with a high degree of uncertainty and difficulties in determination of output parameters will allow one to obtain better results than do conventional systems.