Home – Home – Jornals – Avtometriya 2012 number 1

A method of constructing optimal mask differentiating filters minimizing the level of the root-mean-square or systematic error of estimation of the anisotropic structure orientation observed in the presence of additive white noise is proposed. Results of a comparative analysis of the accuracy of gradient algorithms are presented. It is demonstrated that the use of optimal differentiating filters substantially increases the accuracy of the orientation estimation algorithm.

A class of wavelet filtration algorithms with two-parameter threshold functions is considered. An algorithm is proposed for solving the problem of choosing two threshold values, which allows estimating their optimal values with acceptable accuracy.

The use of the algorithm of real-time determination of local displacements of fragments (blocks) with due allowance for spatial and temporal coupling of motion is proposed for estimating the background component during detecting small-size dynamic objects (in the case of unknown motion of the observation system). The efficiency of this method is compared with that of the methods based on affine transformations of the image as a whole. It is demonstrated that this method is more efficient and ensures background suppression in the difference frame under the condition that it is presented by large zones deforming or displacing relative to each other.

For information generated by an unknown memoryless source, a compression method using nonequivalent symbols is proposed and its optimality is proved.

A possibility of using nonparametric algorithms of pattern recognition in the problem of comparing empirical and theoretical distribution functions of random variables is considered. Results of computational experiments are analyzed.

A method that ensures superresolution in terms of angular coordinates in surveillance systems with a flat antenna array during synthesis of radio-location and radio-thermal-location images of the Earth surface with the help of an airborne station in the real beam mode is proposed. This method is based on reconstruction of reflection and emission fields.

The problem of constructing linear regression models in the presence of errors in input and output data is considered. A statistical test for detecting measurement errors in input data is proposed that does not require a preliminary consistent estimation of the coefficients under the assumption of the presence of errors. The test is validated by Monte-Carlo statistical simulation.

A continuous ant colony algorithm is first proposed to identify fuzzy systems. It is used to construct five fuzzy systems to approximate nonlinear functions of one, two, and three variables. The effect of algorithm parameters on the approximation error is studied. A comparative analysis with other identification algorithms showed an advantage of the proposed algorithm.

Algorithms were developed for the tomographic reconstruction of structure from microscopic images using graphics processors of general application. The effect of noise and the choice of reconstruction filters for tomographic problems in materials science is investigated. It is shown that the use of ρ-filtration in reconstruction allows one to estimate the geometrical characteristics of threedimensional microstructures in amorphous metal alloys.

One possible variant of solving the problem of guidance of an autonomous unmanned underwater vehicle to a given target is considered. At large distances, navigation is based on measuring the time of propagation of acoustic signals. Short-range positioning is ensured by processing images taken by an optical camera. PID control is applied as an algorithm controlling the vehicle position and attitude in space. The proposed algorithm is implemented as a computer code and tested in a series of numerical experiments.

An optical method for measuring the geometric radius and velocity of slip of a wheel rolling on a rail is discussed.

This paper presents the results of experimental studies of staring infrared photodetector arrays (PDAs) designed for use in object recognition systems. A special bench was developed to determine the threshold sensitivity of PDAs to spot irradiation, i.e., the minimum excess of the signal power over the background with allowance for the measuring path and its performance. Estimations were made of the root-mean-square (RMS) noise of the PDA element which determines the detection threshold of the excess of the radiation power of an object over the background in the plane of the entrance pupil.

The use of a diffractive optical element (DOE) in the optical scheme of a laser illuminator of a shooting simulator exposing the target is studied. It is proposed to use the DOE in the optical projection system to form a laser beam with a special intensity profile. The use of the DOE with binary amplitude transmission allows simplification of the manufacture of this block with simultaneous improvement of its performance. The DOE is used as a diffraction attenuator of laser radiation with a period of 2.5 µm and a minimum bandwidth of about 0.8 µm. Results of an experimental study of the laser radiation distribution generated using the DOE and its comparison with distribution of radiation obtained in the usual way are presented.

A method for controlling the asymmetry sign of the spectral intensity of light reflected from a narrow-band filter by fitting the dielectric layer thickness adjacent to the thin metal layer is proposed.

The geometry of anisotropic light diffraction in ultrasound waves excited by a multi-element converter in an optically uniaxial negative crystal of lithium niobate is analyzed. An expression for the refractive index of a diffracted wave was found on the basis of a study of the optical indicatrices of the refractive indices of ordinary and extraordinary light waves in the crystal. A method for calculating the angular frequency characteristics of anisotropic acousto-optic Bragg cells with multi-element converters is proposed.

Two copper mirrors with different surface roughness are studied by means of spectroscopic ellipsometry. It is established that spectral dependences of optical conductivity are qualitatively similar, but shifted along the ordinate, and some of their peaks may be related to light absorption by the surface oxide layer.

Gallium arsenide ion-doped field-effect transistors with a Schottky barrier and various doping profiles are modeled. Dependences of static transistor characteristics on doping profile parameters are calculated and analyzed. The physical processes that determine the transistor characteristics with variation in doping profile parameters are studied.