Influence of intermolecular hydrogen bonds on the luminescence properties of α-substituted cinnamonitriles

In view of the dramatic difference in the spectral-luminescence properties of α-(p-chlorobenzoyl)-4-diethylaminocinnamonitrile and α-ethoxycarbonyl-4-diethylaminocinnamonitrile in solutions and in the crystalline state, X-ray diffraction analysis has been applied to study crystals of these compounds. The intermolecular C-H...N and C-H...O hydrogen bonds are found to contribute to the quinoidization of molecules, which leads to a bathochromic shift in the absorption and fluorescence spectra. A spectral-luminescence study of the aforementioned compounds has revealed that the solvent temperature and polarity affect the position of absorption and luminescence peaks: a decrease in these parameters causes a hypsochromic shift.     

Equivalence of Differential Operators in Spaces of Analytic Functions over the Tate Field

We obtain conditions for the equivalence of certain differential operators in spaces of analytic functions over the Tate field.     

Uniqueness theorems for multiple lacunary trigonometric series

In a many-dimensional space, we study some properties of functions with lacunary Fourier series depending only on the values of these functions in a neighborhood of a certain point. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 11, pp. 1477–1481, November, 1998.     

Film cooling by injection into a turbulent boundary layer

Most papers on film cooling concern injection of a homogeneous gas. Stollery et al. [1] examined the case of tangential injection of gas into a boundary layer, the specific heat_63-01 differing little from that of the main flow,_63-02.Here we examine the effectiveness of film cooling of a thermally isolated planar wall by local supply to a turbulent boundary layer.     

Effect of compressibility and nonisothermicity on the efficiency of film cooling in a turbulent boundary layer

Most studies of film cooling deal with the analysis of the thermal shielding efficiency in an incompressible gas flow with constant physical properties. In practice, however, film cooling is used for machine elements exposed to high-speed, high-temperature gas flows. These conditions have received relatively little attention [1–3]. In this paper the influence of these factors on thermal shielding efficiency is analyzed by the method proposed in [4]. It is shown that the effect of compressibility and nonisothermicity on the thermal shielding efficiency is not very great.     

Heat transfer in a turbulent boundary layer with stepped injection

The asymptotic theory of a turbulent boundary layer has been applied to derive relationships for the heat and mass transfer when there is injection and consequent nonuniformity in the gas composition. Experimental studies are reported on heat and mass transfer with stepped injection of homogeneous and inhomogeneous gases; the results confirm the equations for the heat and mass transfer at a permeable surface when a foreign gas is blown in.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 124–129, July–August, 1973.     

Low-density jets beyond a sonic nozzle at large pressure drops

The gas-dynamical structure of jets of a low-density diatomic gas beyond a sonic nozzle at large pressure drops under conditions of a transition from continuous medium processes to rarefied gas processes is examined on the basis of experimental data obtained in low-density gas-dynamical tubes using electron-beam diagnostics and the Pitot tube method. Isomorphism is shown in the density distribution and total pressure in all cross sections of the jet with respect to pressures at a constant value of the complex R_L=R_*/N^1/2(R_* is the Reynolds number in the critical cross section of the nozzle, and N is the ratio of the Pitot pressure and the pressure in the discharge chamber). It is shown on the basis of a comparison of local Reynolds numbers for all zones of the jet that this is an analog complex. The experimental data on the variation in the jet structure are presented as a function of the number R_L in the range of 5–600. For R_L> 100 the flow in the jet can be considered as continuous; for R_L< 5–10 the flow corresponds to a scattering process; the range of 5–10< R_L< 100 corresponds to a transitional state. Ranges of isomorphism of the jet with respect to R_* and N are indicated. Based on the results of the measurements, it is shown that the flow behind a Mach disk for R_L> 200 remains subsonic on the axis to a distance of several lengths of the primary cycle. A transition to supersonic velocity on the jet axis can occur with a decrease in the numbers R_L owing to ejection acceleration by the supersonic ring-shaped compressed layer.This word is apparently interchangeable with self-similarity-Translator.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 64–73, March–April, 1973.