Optoelectronics, Instrumentation and Data Processing (v.52, #3)

An algorithm is proposed for estimating the coordinates of nodes of deformed lattices of quasiperiodic textures without preliminary detection of typical texture elements. Examples are provided to demonstrate high accuracy of the algorithm on the basis of real grayscale images containing quasiperiodic textures.
Keywords: estimation algorithm; quasiperiodic texture; lattice nodes; texture element; local twodimensional spectrum; Bravais lattice

A wavelet in the form of the first odd prolate spheroidal wave function is proposed for the wavelet transform of a non-uniform 2D image and the formation of clusters of wavelet coefficients in it. Methods for calculating the wavelet function, clustering the field of wavelet coefficients, and constructing their corresponding optimal rectangular windows in an image are described. Modeling has shown the high efficiency of the methods and the algorithm implementing them under various real operating conditions of the optoelectronic device..
Keywords: wavelet; prolate spheroidal wave function; non-uniform image; algorithm; cluster of wavelet coefficients; dynamic object

The problem of classification of space multispectral images of forest vegetation is considered. Features based on the wavelet transform and a classification method involving consideration of the importance of each feature are investigated. Dependence of the classification results on the wavelet function, the level of the transform, and the parameter of the classification method — the number of segments of the range of features — is given. Results of classification of multispectral images of six classes of forest vegetation in images obtained by a Rapid Eye shooting system are presented.
Keywords: multispectral images; classification method; wavelet transform; feature importance

Identification potential of online handwritten signature verification by B. N. Epifantsev; P. S. Lozhnikov; A. E. Sulavko; S. S. Zhumazhanova (238-244).
This paper presents a comparison of natural and artificial intelligences in identifying operators of information-processing systems and their functional state based on handwriting. The cause of the large scatter in the person identification error probability is determined. It is concluded that at the present level of knowledge, the best result achieved in solving the problem by artificial intelligence systems is close to that potentially possible. It is substantiated that online handwritten signature verification is suitable for identifying the functional state of operators of human-machine systems in professional activities.
Keywords: information security; subconscious movements; signer identification; artificial intelligence; natural intelligence; intelligence comparison; human state identification

New type of polarization signature for radar images of the Earth cover with fractal properties by A. V. Dmitriev; T. N. Chimitdorzhiev; P. N. Dagurov (245-251).
A new type of the polarization signature is proposed for estimating the anisotropy of spatial inhomogeneities of the Earth cover with the use of polarimetric radar images taken from space. The case of radar imaging of a pine forest in a decimeter band of wavelengths at different azimuthal angles is considered.
Keywords: remote sensing; synthetic aperture radars; fractal dimension; image processing

Simulation of visual instrumental observations of the Earth from the International Space Station by V. S. Bartosh; I. V. Belago; M. S. D’yakov; S. A. Kuzikovskii; A. S. Pereverzev (252-258).
This paper discusses the features of training simulation for solving problems of visual and instrumental observation and observation of the Earth from the Russian Segment of the International Space Station (ISS). Approaches satisfying the requirement of real-time rendering of the digital visual Earth model with a resolution of up to 15 m/texel with viewing angles of 2 to 110° in a simulation of ISS flight are described. A solution is presented which allows simulating camera observations using a positioning system. The characteristics of the developed software and hardware are given.
Keywords: training simulation; visual and instrumental observations; digital visual Earth model; positioning system; space-filling curves; virtual reality system

The problem of reconstruction of the sound speed profile in the water column in a shallowsea waveguide by means of geoacoustic inversion from single-hydrophone recording of a pulse signal is considered. A method for solving this problem with the use of high-performance computer systems is developed and implemented. Numerical experiments performed by using this algorithm show that the sound speed profile in the water column can be reconstructed on the basis of some very rough estimates for geoacoustic parameters of the bottom. The use of these rough estimates does not affect the accuracy of sound speed profile reconstruction provided that the signal spectrum contains some components of sufficiently high frequency.
Keywords: sound speed velocity; modal dispersion; inverse problem of geoacoustics; computational cluster; parallel computations

Initialization method for fuzzy Takagi–Sugeno systems by I. A. Hodashinsky; K. S. Sarin; S. A. Cherepanov (266-273).
This paper presents a method for initializing Takagi–Sugeno fuzzy systems in which the initial values of fuzzy antecedents are obtained by dynamic decomposition of the input space while the consequent values are obtained by the recursive least squares method. The results of experiments on 13 datasets from the KEEL repository are described. The results of approximating these datasets by the proposed method are compared with those obtained by five well-known identification algorithms..
Keywords: initialization; fuzzy systems; dynamic partitioning; recursive least squares method

This paper considers the use of a cascade compensator embedded in a Smith predictor in the forward path of a system being designed, which is an effective way to solve two problems: providing the desired process performance in the system and placing the dead-time element outside the closed loop so that it only increases the transient time by the value of the time delay and does not affect the overshoot value. It is shown that the Smith predictor should be used with caution because, being based on an additive signal compensation scheme, it may be not robust and may require accurate knowledge of the time-delay value for robust implementation. The problem of sensitivity analysis of the system to dead-time variation is stated and solved.
Keywords: continuous plant; dead-time element; cascade compensator; Smith predictor; sensitivity to dead-time variation

A method of real-time reconstruction of the useful signal and its lower derivatives on the basis of a recurrent smoothing spline is presented. A calculation technique for a spline with the number of measurements at each segment greater than the number of nodes is given, and the spline coefficients are found by the variational approach.
Keywords: reconstruction of the function and its derivatives; recurrent algorithm; variational smoothing spline

Nucleation of two-dimensional Si islands near a monatomic step on an atomically clean Si(111)-(7×7) surface by D. I. Rogilo; N. E. Rybin; S. S. Kosolobov; L. I. Fedina; A. V. Latyshev (286-291).
The process of nucleation of 2D islands near a monatomic step at the initial stage of growing of a silicon film on the Si(111)-(7 × 7) surface is studied by means of in situ ultrahighvacuum reflection electron microscopy. The dependence of the depletion region width W near the step, where no islands are formed, on the deposition rate R is described by the expression W 2R with the exponent χ = 1.18 and χ = 0.63 at temperatures of 650 and 680 °C, respectively. It is demonstrated that the change in χ is associated with the step structure, which provides the transformation from the growth kinetics limited by attachment of adatoms to the step to that limited by diffusion of adatoms. A competition of the processes of nucleation and attachment to the step leads to an increase in the critical size of the island nucleus from i = 1 far from the step to i = 3–5 near the step and to i = 6–8 on the terrace of critical width for 2D nucleation.
Keywords: silicon; epitaxial growth; two-dimensional islands; atomic steps; critical nucleus; surface diffusion; reflection electron microscopy

Proximity effects in formation of photonic crystals by lithographic methods by E. E. Rodyakina; K. A. Konfederatova (292-297).
Proximity effects in formation of photonic crystals in the form of ordered arrays of holes of similar radii close to 100 nm by methods of electron beam lithography are considered. The coefficients of the proximity function characterizing the contribution of back-scattered and secondary electrons to the exposure dose are experimentally determined. It is demonstrated that the minimum standard deviation from the mean radius of the elements in the array is provided by means of the proximity effect correction with the use of experimentally obtained coefficients and an iterative equation with an increased contribution of back-scattered electrons.
Keywords: photonic crystals; electron beam lithography; nanostructuring

Deaccelerating films for picosecond new generation dissectors by N. V. Ageeva; S. R. Ivanova; A. S. Komel’kov; G. P. Levina; V. A. Makushina; Y. M. Mikhal’kov; T. A. Skaballanovich (298-303).
This paper describes the selection of deaccelerating films made of aluminum of various thicknesses (300–500 nm) and intended for deacceleration of electrons (with an energy of tens of kiloelectron volts to tens of electron volts) in the developed new generation picosecond dissectors. The designed dissectors should be different by a higher temporal resolution as compared to the maximum reached (~20 ps) in LI-602 dissecting image-tube converters used for diagnosing synchrotron radiation. This paper also presents the results of comparative measurements of emission characteristics of manufactured films in the models of image-tube converters similar in design to a PIF-01/S1 device, which is the basis of the developed dissectors and which provides the maximum temporal resolution of up to 1 ps in the streak mode with the streak speed of ~1010 cm/s. It is established that, when the energy of the incident electron beam equals 10 to 12 keV, the optimum thickness of the deaccelerating aluminum film is 400 nm with the effective secondary emission coefficient equal to 0.7.
Keywords: image-tube converters and dissectors; deaccelerating films; secondary emission; synchrotron radiation

Calibration of an image-tube picosecond dissector by O. V. Anchugov; V. L. Dorokhov; G. Ya. Kurkin; E. I. Zinin; P. A. Molyavin; O. I. Meshkov; D. A. Shvedov; A. V. Petrozhitskii; P. B. Gornostaev; A. I. Zarovskii; E. V. Shashkoff; A. V. Smirnov; M. Ya. Shchelev (304-310).
This paper describes a new image-tube dissector based on a PIF-01 chronographic image-tube device developed and manufactured at the Prokhorov General Physics Institute of the Russian Academy of Sciences (PGPI RAS). The results of the static measurements of the instrumental function of the dissector showing that its temporal resolution can be higher than 4 ps are given. These data are confirmed by direct measurements on the bench of the PGPI RAS with the use of a femtosecond titanium-sapphire laser.
Keywords: streak camera; dissector; picosecond; titanium-sapphire laser; optical diagnostics; cyclic accelerator

This paper describes a fiber-optic transmission system for access networks with frequency division of channels formed in optical, microwave, and radio-frequency bands. The single side band optical modulation and different modulation formats of subcarrier channels are studied. The estimated relationships for estimating the number of spectral and subcarrier channels are given with account for the effect of stimulated Raman scattering and optical preamplifier noise.
Keywords: fiber-optic transmission system; single side band optical modulation; dense wavelengths division multiplexing; subcarrier multiplexing