Home – Home – Jornals – Avtometriya 2018 number 4

An algorithm for estimating the node coordinates of deformed lattices of quasiperiodic textures with subpixel accuracy is proposed. The algorithm consists of two steps. In the first step, the vectors of the frequencies and initial phases of a polyharmonic brightness function model are calculated from the characteristics of spectral outliers of image fragments. The obtained estimates are used to determine the coordinates of the nodes of local lattices. In the second stage, the local lattices are combined into a global lattice for the entire image of the quasi-periodic texture. Using high-accuracy estimates of model parameters from small image fragments ensures stable operation of the algorithm for significant deformations of the lattice and sub-pixel accuracy in estimating the coordinates of its nodes. Results of computer simulation and processing of real halftone images of quasiperiodic textures are given demonstrating the effectiveness of the proposed algorithm.

The errors of estimates of the size, depth, and magnetization of a local source of a simply shaped magnetic anomaly are studied by means of a comprehensive analysis of the magnetic survey performed at different altitudes. Numerical simulations show that the values of magnetic induction induced by the presence of a magnetic source measured at different altitudes provide a more accurate estimate of some parameters of this source than the measurements performed at one altitude.

This paper touches upon the problem of a compact polygonal description of objects. A method of lossless compression of geometric data based on perturbation functions is proposed. Advantages of this approach over the known algorithms of transformation of three-dimensional models for fast transmission of information and its compact storage are demonstrated.

A selective segmentation method is developed that correctly recovers the boundaries of an object in the plan and estimates the depth range of its location. This method assumes the processing of electrical profiling data: shallow electrical profiling and vector patterns of dominant directions of changes in the medium resistance. The boundary of the object is estimated on the basis of using a fuzzy c-means clustering algorithm, adapted to analyze the multidimensional electrical profiling data. The depth range of the object location in the soil is estimated on the basis of using the scalar product function with respect to the vector patterns of dominant directions, adjacent in depth. The effectiveness of the method is confirmed by the computer simulation results and the example of processing of the full-scale experiment on an archaeological site, which is a medieval fortified settlement.

This paper describes the concept and methods of space-time processing of radio images of small objects in a multi-position system of radiometers, which make it possible to increase the performance of this system. The spatial processing is carried out in each overlook cycle of scanning radiometers in order to determine the spatial coordinates of objects and mutual orientation of coordinate systems. The time processing is carried out in a sequence of overlook cycles of radiometers for determining the trajectory parameters of the objects that change mutual positions.

When it comes to a two-position system detecting the amplitude and difference of instances at which a wave arrives at receiving positions, there is a new method for determining the range and location of radiation sources. This paper presents equations that make it possible to study the procedural error and accuracy characteristics of the method for various observation conditions and the results of a computational experiment. Recommendations on the application of the method are given.

A model of simultaneous tonal masking that isolates speech signal components perceived by a human's auditory system is under study. An algorithm of simultaneous masking on the basis of this model. It is shown that, after simultaneous masking, a signal is represented by a binary structure reflecting the harmonic structure of a vocalized sequence. It is experimentally proved that this structure can be used to isolate key (in terms of perception of the auditory system) speech sections. This structure serves as a basis for the algorithm of high-quality speech signal division into vocalized and unvocalized sections, which does not require training before use. According to the results of testing of the joint use of algorithms for simultaneous masking and division of speech signals, the quality of their performance is obtained.

This paper proposes and theoretically justifies a method for noncontact operational measurement of specific electric conductivity and dielectric and magnetic permeabilities of materials via pulse sensing of the controlled surface. An electromagnetic pulse reflected from a controlled object carries information in its spectral composition about measured parameters that can be calculated by the proposed technique.

A tunable (in terms of the angle of convergence of intersecting light beams) two-beam interferometer with fixed mirrors and a fixed photosensitive element is considered. The photosensitive element is based on a symmetric beam-splitter block where tuning of the interference pattern period is ensured by only one type of motion: interferometer rotation with respect to the motionless source of the collimating light beam. It is demonstrated that the period can be controlled in this way for convergence angles from 30 to 180º; the beam diameter should be at least 10 % of the beam-splitter block length. In this region, the greatest width of the range of convergence angle tuning can exceed 40º, and the admissible beam diameter approaches 40 % of the beam-splitter block length. Comparisons with a similar interferometer based on a beam-splitter cube are performed, and possible areas of application of the considered interferometer are determined.

This paper presents the results of development and investigation of compact waveguide electro-optical modulators using original synthesized chromophore-containing polyimides with covalently attached commercial DR-13 dye. Fully polymer electro-optical planar structures with phase-polarization and amplitude modulators in the form of a Mach - Zehnder interferometer were developed and implemented. The characteristics of the developed modulators at a wavelength of 1.3 μm were investigated, and a half-wave voltage of 24 B for the active part of the modulator 1.3 cm long was achieved.

A method used for calibration of scanning modules on the basis of galvanometric deflectors is considered. The method is based on an iterative two-step algorithm of processing of the profilometry map of the test recording of the calibrated module. It is demonstrated that high accuracy and robustness of determining the coordinates of the reference points of the test recording can be obtained by means of finding the approximate positions of such points and identifying the fragment in the vicinity of these points at the first step and searching for the exact values of the coordinates by the correlation method at the second step. The use of this method and a simple algorithm of piecewise-planar interpolation offers a possibility of laser beam positioning with a relative error of 10^-5 from the recording field.

An experimental structure of an optoelectronic system for contactless measurements of micro- and nanodisplacements of moving MEMS elements is considered.The system is based on a heterodyne interferometer with a frequency-stabilized He-Ne laser and an acousto-optical modulator of laser radiation. A resolution of less than 1 nm in terms of the moving element displacement is reached in experiments by applying voltage pulses with amplitudes up to 1 V on the MEMS structure; moreover, the displacement amplitude is found to be a linear function of the control voltage with sensitivity of 100-200 nm/V. No hysteresis is observed on the curve plotted in the coordinates of the element location and control voltage.

The photoextraction of rubidium atoms from the volume of a photonic crystal has been investigated. It has been found that in the case of crystal irradiation in the stop zone where the desorbing light does not penetrate deeply, the separation of atoms occurs practically from its surface, so that the density of desorbed atoms in the cell decreases only exponentially. In the case of irradiation of the crystal outside the stop zone, the volume of the crystal is irradiated almost completely. In this connection, the exponential decrease in the density of atoms in the cell is replaced by its relatively slow reduction of diffusion nature. The volume diffusion coefficient rubidium atoms in the photonic crystal was measured to be 2 x 10^-8 sm²/s.

Channels with and without memory in the simplest Gaussian noise distribution model are compared. It is shown that both channels have similar dependences of the capacity on the average signal power. At the same time, the optimal input alphabet for the channel with memory changes. The applicability of the model with nonlinear memory to the QPSK communication line with a periodic dispersion compensation is demonstrated numerically.

The formation and dynamics of excitations in an atomic or molecular nano chain of a helical shape is studied. The dipole-dipole interaction of the circular polarizations of optical transitions of neighboring molecules is taken into account. The derived Bloch equations are solved in a continuum approximation using the Frenet - Serret coordinate system. Solutions that describe the formation of stable localized structures, solitons, due to the curvature of the chain, which can have a critical influence on the luminescent properties of the chiral medium.