Том 61, № 7 (2016)

The 3D vector problem concerned with the diffraction of the horizontal half-wave vibrator field by a perfectly conducting and infinitely thin rectangular screen is solved during observations at a finite distance from the vibrator. The technique for calculating the diffracted field, which is based on the laws of geometric diffraction theory and uniform diffraction coefficients obtained from the rigorous solution to the problem of the diffraction of the field of a Hertzian electric dipole at the edge of a perfectly conducting semiplane, is proposed. Fast-acting programs for calculating and analyzing the amplitudes and phases of the components of diffracted and complete vibrator fields in the entire space of observation angles at the set distance of the observation point from a rectangular screen and along the normal to the screen under changes in the distance between the screen and the observation point are developed. The character of the transformation of the spatial amplitude distribution of three field components depending on removal of observation point from an antenna is studied. It is shown that the distance to the far field zone of the investigated radiating system exceeds two wave lengths.

Far-field patterns of the external Sestroretskii cube with the edge size of 1 mm for the frequencies of 1, 150, and 300 GHz are presented. The paradox of the external Sestroretskii cube and its relation to the paradox of the external Huygens cube are revealed.

A nonlinear regression model on the basis of the covariance approximation of a multidimensional probability distribution is constructed. The model is represented by an expansion in the basis functions in the form of partial derivatives of the logarithm of the joint factor probability distribution. The weight coefficients of the expansion are the covariances of the resulting and explanatory variables. On particular examples, the efficiency of the Bayesian approximation of the proposed regression model in which the factor distribution is described by a finite mixture of ellipsoidally symmetric densities is demonstrated.

A numerical analysis of the liquid motion in a spherical capacitor under the applied voltage pulse with a duration of several nanoseconds and a peak value to 300 kV is performed. A system of hydrodynamics equations written in the general form in the spherical coordinate system and the Tait equation of state are used to simulate the liquid motion. The electrostrictive pressure is calculated for a liquid in the form of a dipole dielectric.

A model of the electron-optical system with straight axis and a finite-width ribbon beam is constructed on the basis of exact solution of partial differential equations describing a narrow relativistic beam in axisymmetric external magnetic field in the case when the initial rectangular contour is approximated by an ellipse. Rotating and nonrotating beams and curved or planar cathode in the case of emission in the T mode are considered.

Burnout of silicon transistors under the action of a periodic train of electric pulses is experimentally studied. A numerical model and a more physically demonstrative analytical model of the pulse-to-pulse heat accumulation are in qualitative and, to a certain extent, quantitative agreement with the measured results. It is demonstrated that catastrophic failure takes place at a melting point of silicon but additional heat is needed for melting of low-temperature eutectics.

An original technique for manufacturing quartz optical fibers with an elliptical light-guiding core is proposed and tested. The dependences of the ellipticity of the light-guiding core on parameters of the manufacturing process—the temperature of the heating element of the high-temperature furnace and rarefaction inside the cylindrical tube preform—are studied. Test fiber samples are drawn and their optical properties are investigated.