Home – Home – Jornals – Avtometriya 2011 number 6

An approximate method is developed for calculating the systematic and root-mean-square errors of the algorithm for estimating the anisotropic texture orientation on the basis of a gradient structure tensor. It is demonstrated that the method is highly accurate and computationally efficient, as compared to the method of computer modeling.

The notion of the Catalan numerical sequence is extended. Problems leading to generalized Catalan numbers are formulated and solved.

A solution of the problem of reconstructing the coordinates of a 3D-object from parallel projections in the form of its shadows is considered. It is shown that the conjugate points required for the reconstruction are located on the extreme line which passes through these projections the line. An algorithm is developed to detect conjugate points lying on the contours of shadows.

This paper considers the problem of obtaining the shape of spatial group point objects using the principal component method, which allows one to find a rotation-invariant representation of quaternion signals defining spatial group point objects. An advantage of this approach is the possibility of estimating rotation parameters in the absence of information on the numbering of points in the object.

Devices used for testing of infrared imaging systems are briefly reviewed. Popular methods of dynamic scene generation in the infrared range, which are used in testing systems, and their basic parameters are presented. Approximate schemes of constructing such testing systems, based on arrays of controlled micromirrors and emitting elements, are described. A comparative analysis of the most popular testing systems is performed.

This paper presents a mathematical description of the dynamic properties of nonlinear random physical signals, i.e., signals modeled by random functions of time (processes and sequences) with a nonlinear the regression. It is shown that traditional methods of correlation and spectral analyses are poorly suitable or not at all for representing their dynamics. As an alternative, the paper gives a description and analysis of such signals using time (concorrelation functions) and frequency (conspectral density) concors. They exist for all random functions and the modulus of their values re invariant to any instantaneous one-to-one monotonic transformations of signals.

A model of parallel queueing of requests is developed for a queueing system consisting of two units with an unlimited number of servers in each unit and with retrial queueing in the units. An analytic expression is obtained for the generating function of the multi-dimensional state probability distribution of the random vector which characterizes the number of requests in each unit and the number of repeated calls to each unit in a nonstationary mode.

Results of an analytical study of the properties of a diffraction interferometer with the general path of noninverted wavefronts are presented. The interferometer is based on the Fresnel zone plate and designed to control the shapes of surfaces and second-order mirrors. It is shown that application of the theory of pupils and windows allows an essential simplification of consideration of optical systems, visual analysis of the shape of interference fringes, and calculation of the optimum design of an interferometer. The obtained formulas, which relate the positions of pupils and windows (entrance, intermediate, and exit ones) to the zone plate focus and the mirror curvature radius, can be useful in the development of diffraction interferometers of various designs.

Results of a study of elements of solid-state electronics by holographic interferometry are presented. Examples of measurement of thermal strains of real products and control of engineering processes in the production of static induction transistors (SITs) and ultra-high frequency hybrid integrated circuits are given.

A new approach to the wavefront (phase) reconstruction from interferograms is proposed based on the classical method of fringe tracing using a sample of interferograms with different numbers and orientations of interference fringes. Wavefronts reconstructed from individual interferograms are averaged, and the test surface quality is judged by the data obtained. Averaging the phase by several interferograms makes it possible to reduce the variance of the phase reconstruction error caused by random noise and inhomogeneities in aperture illumination and interference fringe distribution, as well as to reduce the effect of instability of external conditions.

The interaction of ultrashort pulses and their bound states in fiber lasers with a saturable absorber are analyzed by numerical simulation. It is shown that the distance between two interacting pulses in the lasing mode established after a transient process can take a set of quantized values in which neighboring pulse separations correspond to steady bound states of opposite parity. Characteristic changes in the established states with a change in the parameters of the laser system are demonstrated. The developed model of passive laser mode locking and the results presented in the paper can be used to describe and interpret the lasing modes of fiber lasers with nonlinear losses due to different nanomaterials (media with quanta wells, nanotubes, graphene, etc.).

Specific features of operation of a two-capacitor generator based on overflow of the charge accumulated in capacitors through a load resistance between two capacitors with antiphase modulated capacitances by means of a lateral or planar shift of the electrode plates by applying a mechanical force to moving electrodes are analyzed. Numerical solutions for all generator operation modes are obtained, and they are found to be universal. Analytical estimates of the maximum power of the generator as a function of the capacitance modulation factor are derived. Experimental investigations of a twocapacitor rotor generator show that its characteristics are consistent with the analysis performed and that this analysis can be used to describe all specific features of operation of particular generators.