Hot-wire anemometer measurement of local skin friction coefficient

Based on fine measurement of time-averaged data of hot-wire anemometer we have developed the method determining local values of skin-friction coefficient in the vicinity of the wall on the planar porous surface at the flow past which the noncanonical turbulent boundary layer is formed. The method may be applied at investigation of the efficiency of various effects on the incompressible boundary layer, in particular, with microblowing of air where usage of direct methods of friction determination is complicated.     

Experimental study of the elements of acoustic screens made of rubber with cylindrical voids

Acoustical Physics - For samples of screens made in the form of a steel layer with an overlying stack of rubber layers with cylindrical voids, the reflection and transmission coefficients are...     

Influence of vacuum annealing on the asymmetry of the electrical conductivity of tantalum pentoxide films

In this work we demonstrate the influence of interphase interaction processes, taking place at the layer boundaries during vacuum annealing of Ta-Ta₂O₅ sandwiches, on the asymmetry of the electrical conductivity of Ta₂O₅ films. These processes are demonstrated to be local in nature.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 46–50, January, 1991.     

Physicochemical properties of membranes based on MSC-H and purolite CT-275 sulfocation-exchange resins

Various methods for synthesis of heterogeneous membranes based on MSC-H and Purolite CT-275 sulfocation-exchange resins were considered. The efficiency of a combined method for fabrication of membranes, based on casting followed by rolling, was analyzed.     

On the study of artificial ionospheric turbulence by means of stimulated electromagnetic emission

Results of measurements of the characteristics of stimulated electromagnetic emission induced in ionospheric plasma by pulsed high-power radio waves (diagnostic emission) presented. The dependences of the properties of diagnostic emission on the parameters of the diagnostic wave, ionospheric conditions, and the level of development of artificial ionospheric turbulence are determined, and criteria are given for selection of optimal diagnostic conditions for ionospheric-plasma sounding. Results of experiments on the sounding of artificial ionospheric turbulence by means of diagnostic emission are provided. It is established that with transition from daytime to evening conditions, the characteristic times of emission decay are sharply increased. This is attributed to an increase in the natural perturbation of the F-region.Scientific-Research Radio-Physics Institute, Nizhny Novgord. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 7, pp. 909–928, July, 1994.     

Swept-Wing Boundary Layer Receptivity to a Steady Free-Stream Vortex Disturbance

A single trailing vortex developed behind a micro-wing immersed in a free stream was used to study the vortex receptivity of a swept-wing boundary layer. As a result of the interaction, longitudinal-velocity disturbances develop in the boundary layer. On the swept wing, disturbance transformation occurs near the leading edge and is accompanied by the formation of a wave packet consisting of waves typical of cross-flow instability. Disturbances with other characteristics are also detected. These disturbances may be attributable to distributed boundary-layer receptivity to the free-stream vortex disturbance considered.     

Self-organization of amphiphilic liquid-crystalline dendrimers in bulk and at the interface

A comparative analysis of the structure and phase behavior of synthesized carbosilane amphiphilic LC dendrimers of the third generation containing mesogenic phenyl and oligo(ethylene glycol) fragments is performed. When phenol groups are replaced with oligo(ethylene glycol) moieties, the temperature interval of the existence of the LC phase in the mesogen-containing dendrimers decreases. The chemical nature of hydrophilic terminal groups is found to control the organization of dendrimers in the smectic mesophase. Structural models for their packing are proposed. Amphiphilic dendrimers are shown to form stable Langmuir films at the water/air interface. Surface-pressure-surface area-isotherms are constructed. The effect of the chemical nature of hydrophilic groups on the formation of a monolayer at the interface and on the packing density of dendrimer molecules in the monolayer is discussed.     

Orientational optical nonlinearity of nematic liquid crystals induced by high-molecular-mass azo-containing compounds

Processes of light-induced reorientation of nematic liquid-crystalline molecules induced by the addition of low concentrations (0.1–2.0 wt %) of comb-shaped polymers and carbosilane dendrimers containing azobenzene fragments are studied. When the molecular structure of the above compounds becomes more complicated, the induced orientational nonlinearity increases. The introduction of 2G and 3G dendrimers into a nematic has for the first time made it possible to visualize and study a purely optical first-order Freedericksz transition in the field of a linearly polarized wave.