Jet noise control using the dielectric barrier discharge plasma actuators

We study experimentally how plasma actuators operating on the basis of surface barrier high-frequency discharge affect jet noise characteristics. The results of investigations of air jets (100?C200 m/s) have demonstrated that the studied plasma actuators have control authority over the noise characteristics of these jets. An actuator??s effect on the jet in the applied configuration is related to acoustic discharge excitation and to a large extent is similar to the well-known Vlasov-Ginevsky effect. It has been shown that jet excitation in the case of St ?? 0.5 using the barrier-discharge plasma actuator leads to broadband amplification of jet sound radiation. The jet excitation in the case of St > 2 leads to broadband noise reduction if the action is sufficiently intensive.     

Stressed state near a wedge‐shaped twin with a disbalance of densities of twinning dislocations

The influence of disbalance of densities of twinning dislocations at the boundaries on the stressed state inside a wedgeshaped twin, near its top, and in external regions adjoining the twinning boundary is studied using a dislocation model.     

Twinning in boron-ion-irradiated bismuth single crystals subjected to mutually orthogonal electric and magnetic fields

The effect of electric pulses (duration 10⁻⁵ s and current density up to 60 A/mm²) and an external magnetic field (0.2 T) on the behavior of wedgelike twin ensembles in boron-irradiated bismuth single crystals was studied. The irradiation energy and dose were, respectively, 25 keV and 10¹⁷ ion/cm². When the crystals were exposed to the magnetic field, both irradiation and pulse application enhanced the mobility of twinning dislocations. An equilibrium condition for twinning dislocations in the irradiated material simultaneously subjected to the electric and magnetic fields was derived.     

Generation of the third harmonic of a surface wave in a semiconductor-metal delay structure

Khar'kov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiiofizika, Vol. 34, No. 6, pp. 724–728, June, 1991.     

Nonlinear interactions of azimuthal surface waves in a magnetoactive plasma waveguide

Several possible three-wave and four-wave interactions, namely decay and modulational instabilities of a specific type of surface waves-azimuthal sufaces waves (ASW)-in a magnetoactive plasma waveguide are considered. The studied ASW propagate in the azimuthal direction at the cylindrical waveguide wall-plasma interface.     

Effect of the loading rate on the mechanism of plastic deformation in bismuth

Mechanisms of plastic deformation of bismuth single crystals that are operative upon the deformation of the (111) plane using a Berkovich indenter at a loading rate of 1–10 mN/s were studied. The plastic deformation in the range of the loading rates studied was established to occur mainly by pyramidal slip.     

Measuring the Impulse Response of an Acoustic MLS Signal in a Moving Medium

Acoustical Physics - The paper presents the results of an experiment that uses the MLS technique to measure the impulse response when a signal passes through an air jet. The data are compared with...     

Entropy-driven triple point wetting in hard-rod mixtures

We theoretically study binary mixtures of thin and thick hard rods with diameter ratio more extreme than 1:4. The bulk phase diagram of these systems exhibits a triple point, where an isotropic (I) phase coexists with two nematic phases ( N1 and N2) of different composition. Using density functional theory, we predict that the I-N2 interface is completely wet by N1 upon approach of the the I-N1-N2 triple point. This entropic triple point wetting should be experimentally observable in colloidal suspensions of rodlike particles.