## Low-temperature surface piezoelectricity in strontium titanate ceramics via piezoresponse force microscopy

Published in category «Condensed matter physics»

SrH0[3] ceramics has been investigated by piezoresponse force microscopy at low temperatures. Interesting behavior of ferroelectric properties was observed at temperature of antiferrodistortive phase transition and in the range of temperatures where Muller phase exists.

## The model of simultaneous double-state losing in semiconductor QD lasers

Published in category «Condensed matter physics»

We have provided theoretical investigation of the double-state lasing phenomena in InAs/InGaAs self-assembled quantum dot lasers. It is shown that the difference between electron and hole capture rates leads to decrease of output lasing power via QD ground states with increasing current. Taking into account this effect makes it possible to describe observed watt-ampere characteristic and its spectral components both qualitatively and quantitatively.

## The influence of structural factor on the configuration of linear vortex in the 3D-ordered Josephson medium

Published in category «Simulation of physical processes»

The systems of difference equations describing two possible current configurations of linear vortex in the 3D ordered Josephson medium based on the conditions of fluxoid quantization in the cells are obtained. The theoretical investigation was realized on the assumption that magnetic field in a cell is not homogeneous.

A method of exact solutions of the systems in case of both configurations of linear vortex for all values of parameters is proposed. The current configurations for linear vortex as well as the values of full energies of both configurations are calculated.

## Embedded large eddy simulation with the use of a volume source of turbulent fluctuations

Published in category «Simulation of physical processes»

A simple and effective method for computation of turbulent flows within the Embedded LES framework is proposed. The method is implemented in general purpose FLUENT code and its tests show that both attached and separated flows are predicted by the proposed method with a high accuracy.

## Calculation of the micro-XRF spectrometer scheme geometry

Published in category «Devices, Information-measuring Systems»

This paper is devoted to optimization of the micro-XRF geometry scheme using a Monte-Carlo simulation. A brief description of the simulation algorithm is given, calculation of the metrological parameters of the microanalysis shows the optimization efficiency

## Calculation of a primary X-ray radiation focusing system in the micro-XRF spectrometer

Published in category «Experimental technique and devices»

This work is devoted to optimization of a primary X-ray radiation formation system in the micro-XRF spectrometer. Some theoretical results are given. Calculations made it possible to simulate work of the X-ray tube — polycapillary X-ray lens system and to define parameters of the combination.

## An estimation of photon beams parameters in the remote radiation treatment from ionization matrices

Published in category «Experimental technique and devices»

A comparative estimation for inaccuracy in profile dependency of photon beams with the energy of 6 MeV has been considered using experimental data from ionization matrices and water phantom with ionization chambers. The regions of practicality for a matrix to test the photon 6 MeV beams quality under the clinical conditions were analyzed. The practical recommendations are given how to carry out the optimizing procedure of dosimetric experimental data during the analysis of therapeutic beam fields.

## The determination of ground ultraviolet radiation intensity from COME data

Published in category «Experimental technique and devices»

The authors propose a method for correction of the function of absorption of the solar energy stream (the ultraviolet) by ozone on the terrestrial surface and a method for the cloud cover account in the Bird's model used for reconstruction of biologically active ultraviolet radiation in the vicinity of the Earth surface from GOME data.

## Technique of digital signal processing of Raman spectra for hydrocarbon lubricants condition diagnostics based on viscosity estimation

Published in category «Experimental technique and devices»

In the presented paper an ability of application of Raman spectroscopy and modern signal processing methods for hydrocarbon lubricants quality estimation has been considered. Principal component analysis and wavelet filtering methods were used for complex signal processing. On the basis of experimental spectra an ability of lubrication oils viscosity estimation was demonstrated.

## econstruction of energy spectra of electrons bombarding a solid target

Published in category «Physical electronics»

A diagnostical method for reconstruction of electron energy distributions on the basis of bremsstrahlung X-ray spectra from electron beam device collector were tested in simulations and experiments. Applicability of the universal Kramers'es law for reconstruction of electron energy distributions has been numerically estimated for different data acquisition layout conditions.

## A simple model of facilitated field-induced electron emission from nanomaterials

Published in category «Physical electronics»

A simple numerical model is proposed to describe the complex of phenomena associated with field-induced electron emission from nanostractured materials. The performed simulations demonstrated that many of the features of experimentally observed emission behavior of nanocarbonic films may be explained in the assumption of indirect (two-stage) mechanism of electron transfer to vacuum via intermediary states located by the emitter surface.

## The electro-optical control of nonmonochromatic light in a system of two anisotropic crystals

Published in category «Physical optics»

The spectral characteristics of emission transmitted through a system of two anisotropic crystals and three polarizers are given. The emission in the system has been demonstrated to be modulated spectrally (it passed through maxima and minima alternating over a wavelength). Resiting maxima and minima in one crystal somebody can get the effective emission intensity modulation at the output of such an optical system. The electro-optical modulator using a light diode of more than ten nanometers spectral wide as a radiation source had a modulation index beyond 80 percent.

## The formation of medium with artificial optical activity

Published in category «Physical optics»

For the purpose of the formation of local chiral surrounding of a given medium point the orbit method of symmetry group is proposed. Gyration tensor is calculated by Discrete Dipole Approximation (DDA) method. The dependence of gyration tensor on cross dipole-toroidal polarizability tensor is established. Examples of computation of the rotation polarization angle which is considered as a function of local environment structure parameters are given.

## Electrical phenomena at interfaces in heterogeneous poly mineral systems dispersed

Published in category «Physical materials technology»

The problems of phenomena taking place in electrically active heterogenious systems dispersed have been considered. The presence of electric forces which cause the self-potential gradients of the internal electric field was revealed at the interface of liquid and solid phases. That field is able to maintain the circulation of currents in such systems. The influence of the double electric layer typical for such systems on forming structure was registered experimentally. The mechanism for electric processing at interfaces of two different polar dielectrics was established.

## New segmented cross-linked poly(esterurethansiloxane) elastomers for medical implants

Published in category «Physical materials technology»

New cross-linked segmented poly(esterurethansiloxane) elastomers have been synthesized for implants of increased strength and durability. It is possible to change the cross-linking density in elastomers by varying of chain segments molecular mass and ratio and chemical structure of a hardening agent.

## Typical limiting problems for the Crocco equation

Published in category «Mathematics»

It is proved that monotone solutions of the limiting problem for the Crocco equation are tantamount to the Cauchy problem with delta-parameter that controls the transport on the left border of an interval of integration.

## The problem of construction of controls over a mechanical system controlled

Published in category «Mathematics»

The paper is devoted to investigation of a guided mechanical goulonom system described by a set of Lagrange's equations of the first kind. The theorems of construction of control over this system are given. They make it possible to construct controls in such a way that the system is asymptotically robust integral manifold.

## The calculation of spin-dependent structure function of a deuteron in a formal description of the light cone

Published in category «Theoretical physics»

The paper views a relativistic deuteron as a system of two intensively interacting nucleons (a dinucleon approach) in a formal description of the light cone. A procedure for consistent calculation of relativistic nuclear corrections to the mean helicity of the proton in the deuteron and the spin-dependent structure g[1]{D}(x,Q{2}) function of the deuteron is shown.

## Quantum mechanics for a vector particle in the magnetic field on four-dimensional sphere

Published in category «Theoretical physics»

Quantum-mechanical wave equation for a particle with spin 1 is investigated in presence of external magnetic field in spaces with non-Euclidean geometry with constant positive curvature. The separation of the t, r, cp, z variables is performed; differential equations in the r variable are solved in hypergeometric functions. The study of z-dependence of the wave function has been reduced to a system of three linked ordinary differential 2-nd order equations; till now the system is not solved.

## New problems in quantum mechanics and the Heun equation

Published in category «Theoretical physics»

The system of equations for electromagnetic field in the Lobachevsky space is transformed into a single equation which formally coincides with an 1-dimensional Schrodinger equation with an effective potential; on this base, analysis of ideal mirror properties of the medium sumulated by the Lobachevsky geometry is performed. The problem of a spin 1 particle in the Coulomb field is reduced to the Heun equation and to a special class of the Heun functions.

## Continuous wavelet transformation

Published in category «Radiophysics»

An annalytical expression of continuous wavelet-transformation for the elementary nonstationary signal which represents work bending around Gauss forms on sine wave function is found. The complex nonstationary signal is represented in the form of superposition of the elementary nonstationary signals. The formula for restoration of a signal on known value of continuous wavelet transformation is resulted, as well as expressions for local density of a spectrum of energy of a signal and spectral integrals are obtained.

## Orientation light shift suppression in alkali atoms microwave standards with laser pumping

Published in category «Radiophysics»

This work presents analytical studies of the orientation and light frequency shifts in microwave standards with regard to tensor component. It was shown that modulation technique application not only allows eliminating light shift but also provides significant reduction of the frequency errors introduced by external magnetic field orientation fluctuations while pumping alkali atoms with either D, or D[2] line.

## Radio-optical resonance frequency light shift in selective optical pumped rubidium vapor

Published in category «Radiophysics»

Theoretical research results of alternative selective optical pumped absorption cell with Rb85 and filter cell containing atoms of Rb87 are presented. And the calculated light frequency shifts for lamp- and laser-pumping are compared.

## Diffraction attenuation of the ultrasonic ray of the cylindrical waveguide created by the end face

Published in category «Radiophysics»

The calculation of diffraction attenuation of an ultrasonic ray in "a piston radiator — a cylindrical waveguide — the investigated environment" system is carried out. It is shown that spatial dispersion presence in an acoustic waveguide leads to the considerable oscillations of diffraction attenuation unlike a field of a piston radiator and also to origin of areas with the negative value of diffraction attenuation.

## Diffraction of electromagnetic waves by heterogeneity of the plasma waveguide

Published in category «Radiophysics»

The analytical model of the processes accompanying dispersion of electromagnetic waves by heterogeneity of a semi-infinite plasma waveguide has been considered. The electromagnetic field extending along a plasma waveguide was led to a system of the pair equations integrated which was transformed to a boundary problem for functions, analytical in planes of the complex variable. Results of the simulation performed have shown a possibility of the account of the contribution of various types of waves in a resultant absent-minded field. Dispersive characteristics for different types of waves were calculated. The expressions were obtained, allowing to estimate a radiation field in a distant zone on the basis of a stationary phase method.

## The excitation of surface waves by an elementary dipole

Published in category «Radiophysics»

The problem of excitation of surface waves by elementary dipole disposed on metallized dielectric slab has been solved. It was shown that dipole radiates surface waves most effectively in the direction along the dipole axis. If electric thickness of dielectric slab is large then the major portion of power is radiated in the form of surface wave.

## The Xlllth All-Russian Young-People Conference on Semiconductor Physics and Nanostructures, Semiconductor Opto- and Nanoelectronics

Published in category «Chronicle»

The article reviews the work of 'The XHIth All- Russian Young-People Conference on Semiconductor Physics and Nano-stractures, Semiconductor Opto- and Nanoelectronics' held in Saint-Petersburg, on November 21 — 25, 2011. The titles of students' and post-graduate students' reports diplomaed at the conference are presented.

## The scientific conference of Russian undergraduates specializing in radiophysics

Published in category «Chronicle»

The information on 'The XVth All-Russian Conference of Undergraduates Specializing in Radiophysics' held in Pet-rodvoretz, on December 6 — 7,2011, at educational center of Saint-Petersburg State University has been represented. The students' and post-graduate students' reports diplomaed and awarded by prizes at the conference were outlined. The contents of three reports were briefly described.