Study of heat transfer in the separation zones formed in front of supersonic jets in a subsonic carrier flow

The heat transfer taking place between the gas and the surface of the plate in the zone of three-dimensional separation of the turbulent boundary layer in front of a set of supersonic jets injected perpendicularly to a subsonic carrier flow is considered. The aim of this investigation is to establish the main physical characteristics of heat transfer in the separation zones in front of jet obstacles and to obtain the distributions of the local heat-transfer coefficients and the temperature of the thermally insulating wall as functions of the parameters of the carrier flow and the injected jets. Analysis of the experimental results yields certain approximating relationships for the distribution of the local heat-transfer coefficients as functions of the Mach number of the carrier flow M, the Mach number of the jet M_j, the relative boundary-layer displacement thickness _s= _s ^* /d, and the degree of jet superheating T_ojT_o relative to the separation zones in front of supersonic jet obstacles.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 68–72, July–August, 1975.     

Luminescence properties of oxide coatings on aluminum alloys

This is a study of the luminescence properties of coatings formed on aluminum alloys by anodizing in electrolytic solutions based on oxalic, sulfuric, and tartaric-sulfonic acids. At least two emission centers, with band maxima in the ranges of 390–410 and 470–510 nm, can be reliably identified in the photoluminescence spectra. The first type of center is characterized by single-band photoluminescence excitation spectra and the second, by two-band spectra. An analysis of the two-band photoluminescence excitation (PLE) spectra in the range of 470–510 nm shows that the position of the narrow short-wavelength PLE spectrum near 272 nm is independent of the type of acid used in the anodization process. The position and shape of the other PLE spectral bands depend both on the type of acid used and on the processing of the alloy or alumina surfaces. It is assumed that defect-free alumina centers are responsible for the 272 nm PLE band, while the other photoluminescence bands are caused primarily by different divacancies of oxygen (F₂⁺ {F_2^+} , F ₂, and F₂⁺² {F_2^{+2}} centers) whose origin is governed by the type of electrolyte.     

On the <Emphasis Type="Italic">σ</Emphasis>-countable compactness of spaces of continuous functions with the set-open topology

For a Tychonoff space X, we obtain a criterion of the σ-countable compactness of the space of continuous functions C(X) with the set-open topology. In particular, for the class of extremally disconnected spaces X, we prove that the space C _λ(X) is σ-countably compact if and only if X is a pseudocompact space, the set X(P) of all P-points of the space X is dense in X, and the family λ consists of finite subsets of the set X(P).     

Influence of the Characteristics of Impact Excitation on the Parameters of Electromagnetic Response from Dielectric Materials

The influence of the energy and duration of impact excitation on the parameters of electromagnetic response from structural dielectric materials is investigated. It is established that the first pulse of electromagnetic response is due to the electrization of the material at the impact point, and the pulse duration determines the active impact excitation phase. The transformation of the amplitude-frequency characteristics of the electromagnetic response attendant to changes of the impact excitation parameters is observed, which testifies to the linearity of mechanoelectric transformations for impact excitation energy of the order of 3·10^–2 J.     

Discrete analog of the Korteweg-de vries (KDV) equation: Integration by the method of the inverse problem

Scientific-Research Institute of Systems Research of the Russian Academy of Sciences. Translated from Matematicheskie Zametki, Vol. 56, No. 6, pp. 141–144. December, 1994.     

Current switching in bistable structures: Heavily doped n +-polysilicon-tunnel-oxide layer-n-silicon

Switching from a state with a steady-state nonequilibrium depletion and low current into the “on” state with a high current and low voltage drop on the structure is observed in highly doped n ⁺-polysilicon-tunnel-oxide-n-silicon structures. The structures were prepared on n-silicon substrates with a resistivity of 25 Ω·cm. A structure with an oxide thickness of 23 Å can be switched on both by a radiation pulse with small reverse bias on the structure (50 V) and under dark conditions by increasing the reverse bias to 250–300 V. In the “on” state Auger carrier production is the internal source of minority carriers that is required for compensating tunnel leakage of holes into the n ⁺-polysilicon and for maintaining a quasiequilibrium inversion layer of holes at the n-Si-SiO₂ boundary.     

Numerical integration of the landau-lifshits-gilbert equation

An efficient projection-difference method is proposed for numerical integration of the equation of motion of magnetization, based on the weak form of the equation.Translated from Metody Matematicheskogo Modelirovaniya, Avtomatizatsiya Obrabotki Nablyudenii i Ikh Primeneniya, pp. 155–159, 1986.