A mixed dynamic problem of the theory of elasticity for a piecewise homogeneous plane

We study the process of splitting of a compressed piecewise homogeneous medium under high-speed motion of a wedge with the formation of a crack of unknown extent ahead of the wedge. The motion of the wedge occurs along the interface between physico-mechanical properties of the piecewise homogeneous plane. We carry out numerical studies. We obtain asymptotic representations of the elastic potentials at the limiting velocities of motion of the wedge. Two figures. One table. Bibliography: 6 titles. Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 26, 1996, pp. 48–58.     

Effect of electric field on the metal-insulator transition with the formation of superstructure

The mechanism of the effect of an electric field on the metal-insulator transition with the formation of superstructure is considered with allowance for the field modulation of the electronic spectrum. Experimental data on the switching effect in vanadium dioxide are interpreted on the basis of this modified model.     

Nonstationary interaction of a supersonic flying object with extended low-density regions in the atmosphere

A three-dimensional numerical model is developed and the aerodynamic loads are determined for the three-dimensional flow acting on a blunt cone flying in the atmosphere along the boundary of a rarefied region, as functions of the degree of immersion of the surface of the body in low-density air. The nonstationary gas-and aerodynamic processes accompanying the entry and exit of the body from the rarefied region are studied. The aerodynamic coefficients obtained with an approximate model are compared with the three-dimensional calculations and found to be in satisfactory agreement with them. Zh. Tekh. Fiz. 68, 32–37 (November 1998)     

Simulation of silicon diffusion in GaAs

The simulation of coupled diffusion of silicon atoms and point defects in GaAs has been carried out for diffusion at the temperatures of 1000 and 850 °C. The amphoteric behavior of silicon atoms in GaAs has been taken into account in the investigation of high concentration diffusion from silicon layer deposited on GaAs substrate. The calculated dopant profiles agree well with the experimental ones and they confirm the adequacy of the model of silicon diffusion used for simulation. A comparison with the experimental data has enabled this work to obtain the parameters of silicon effective diffusivity and other values describing high concentration silicon diffusion in GaAs.     

Investigation of the closed porosity of functional ceramic materials by spin-echo small-angle neutron scattering

The closed porous structure in ceramic materials is investigated by spin-echo small-angle neutron scattering. A series of ceramic samples of oxygen–ion conductors based on bismuth molybdate with the general formula Bi_12.8 X _0.2Mo₅O_{34 ± δ} (X = Mg, Ba, Ca, Sr) is obtained by powder sintering for 6?45 h at a temperature close to the melting point. The samples are characterized by scanning electron microscopy and X-ray fluorescence analysis. It is found that they had a stoichiometric chemical composition, are singlephase, and contain clean pores between crystal grains. The pore size is determined by spin-echo small-angle neutron scattering and ranges from 2.2 to 3.5 μm. It is demonstrated that longer sintering times correspond to larger pores (the increase in their average diameter is as large as 30%). It is found that the studied materials lack a fractal pore structure.     

Dispersion Forces between Metal and Dielectric Plates Separated by a Magnetic Fluid

Technical Physics - The formalism of the Lifshitz theory has been used for determining the pressure exerted by dispersion forces between metal and dielectric plates separated by a thin layer of a...     

Polarization properties of odd comet 17P/Holmes

We present results of polarimetric observations of comet 17P/Holmes that in 2007 surprised the observers by its outburst that resulted in dramatically increased brightness and unusual shape of the coma. Polarimetric properties of the comet also appeared to be very peculiar. Even though the comet showed negative polarization typical for the small phase angles, its absolute values were much lower than usually observed at these phase angles and the spectral gradient of the polarization was much more pronounced than usually observed for comets (although negative that is typical for other comets too). Both these results are different from the regular trends and indicate some specifics of the comet Holmes dust during the outburst. We discuss how such unusual polarimetric properties of the comet can be explained and show how a peculiar combination of aggregated and compact particles or a composition with a unique ratio of silicates to organics can explain the observational results.     

Investigation of the stability of the direct spectroscopic problem of diatomic molecules with non-Dunham power series representation of the potential

The stability of the direct spectroscopic problem of the CO and HI molecules in the singlet electron ground state has been investigated with the potential represented in the Dunham (D), Ogilivie-Tipping (OT), Simons-Parr-Finlan (SPF), and Thakkar (T) form. Introducing the same relative error in the potential parameters of the various representations, we calculated the errors of the wave numbers of the vibration-rotation transition. The direct problem is most stable for T and SPF expansions. The result obtained is important for direct theoretical calculation of spectrum parameters which do not participate in the fitting.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 58–62, October, 1982.     

Telomerization of acrylonitrile and methyl acrylate with methyl dichloroacetate

Conclusions The telomerization of acrylonitrile and methyl acrylate with methyl dichloroacetate at the C-Cl bond of the latter was accomplished by initiation with iron pentacarbonyl in combination with either DMF ordimethylaniline.Translated from Izvestiya Akademii SSSR, Seriya Khimicheskaya, No. 6, pp. 1410–1412, June, 1973.