Determination of Parameters of the Europium Ion Crystal Field by the Luminescence Spectra Obtained by Means of an Acousto-Optical Spectrometer

The parameters of the europium ion crystal field in dipic acid salts have been determined by their luminescence spectra. The sample preparation procedure and the luminescence-measuring technique using an original spectrometer based on an acousto-optical tunable filter have been described. It has been shown that the methods and equipment used permit reliable proximate analysis of the quality of compounds of this type.     

Complex noise suppression using a sparse representation and 3D filtering of images

A novel method for the filtering of images corrupted by complex noise composed of randomly distributed impulses and additive Gaussian noise has been substantiated for the first time. The method consists of three main stages: the detection and filtering of pixels corrupted by impulsive noise, the subsequent image processing to suppress the additive noise based on 3D filtering and a sparse representation of signals in a basis of wavelets, and the concluding image processing procedure to clean the final image of the errors emerged at the previous stages. A physical interpretation of the filtering method under complex noise conditions is given. A filtering block diagram has been developed in accordance with the novel approach. Simulations of the novel image filtering method have shown an advantage of the proposed filtering scheme in terms of generally recognized criteria, such as the structural similarity index measure and the peak signal-to-noise ratio, and when visually comparing the filtered images.     

Analytical theory of hysteresis in ion channels: two-state model

Channel-forming proteins in a lipid bilayer of a biological membrane usually respond to variation of external voltage by changing their conformations. Periodic voltages with frequency comparable with the inverse relaxation time of the protein produce hysteresis in the occupancies of the protein conformations. If the channel conductance changes when the protein jumps between these conformations, hysteresis in occupancies is observed as hysteresis in ion current through the channel. We develop an analytical theory of this phenomenon assuming that the channel conformational dynamics can be described in terms of a two-state model. The theory describes transient behavior of the channel after the periodic voltage is switched on as well as the shape and area of the hysteretic loop as functions of the frequency and amplitude of the applied voltage. The area vanishes as the voltage period T tends to zero and infinity. Asymptotic behaviors of the loop area A in the high- and low-frequency regimes, respectively, are A approximately T and A approximately T(-1).     

Improvement in image resolution based on dispersive representation of data

A method for reconstructing the resolution of images, based on selection and optimization of significant local features and sparse representation of processed-image blocks (using optimized low- and high-resolution dictionaries), has been substantiated for the first time. This method, making it possible to improve significantly the resolution of images of various nature, is interpreted physically. A block diagram of the processing system corresponding to the new approach to image reconstruction has been developed. A simulation of the new method for reconstructing images of different physical natures and known algorithms showed an advantage of the new scheme for reconstructing resolution in terms of universally recognized criteria (peak signal-to-noise ratio, mean absolute error, and structural similarity index measure) and in visual comparison of the processed images.     

Analysis of nonstationary signals and fields with the use of enclosed semi-Markov processes

In this study, the possibility to describe the signals scattered by various physical objects such as underlying surfaces of land and sea, the segments of “clear sky,” and processes of various physical natures, such as fluctuations of the refractive index of the troposphere and electromagnetic and acoustic radiation of a lithospheric nature, by enclosed semi-Markov processes is investigated. This approach makes it possible to construct statistic models for a broad class of signals and processes. In some cases, statistics based on atomic functions and WA systems of the Kravchenko-Rvachev functions show the best results.     

Statistical synthesis of radiometric imaging formation in scanning radiometers with signal weight processing by Kravchenko windows

Statistical optimization of the radiometric images (RMIs) algorithms formation in scanning radiometers with weight correction of the antenna amplitude-phase distribution and synchronous sliding strobing of the received noise-like signal by a function describing the antenna pattern corrected by temporal Kravchenko windows is performed for the first time. The ambiguity function (AF) of the scanning radiometer, which determines the RMI quality, is found. It is established that the AF shape substantially depends on the amplitude field distribution (AFD) in the antenna. It is shown that the use of the AFD in the antenna in the form of weight functions (classic and Kravchenko) makes it possible to correct the AF shape and to increase the RMI quality. A simulation of the RMI formation algorithm is performed. It follows from the analysis of simulation data that the use of the weight Kravchenko functions provides higher accuracy of the RMI restoration compared with classic weight functions.     

A new class of weight and WA systems of the Kravchenko-Kaiser functions

A new class of weight and WA-systems of the Kravchenko-Kaiser functions which showed its efficiency in various physical applications is proposed and substantiated. This publication consists of three parts. In the first the Kravchenko-Kaiser weight functions are constructed on basis of the theory of atomic functions (AFs) and the Kaiser windows for the first time. In the second part new constructions of analytic WA-systems of the Kravchenko-Kaiser functions are costructed. In the third part their applications to problems of weight averaging of the difference frequency signals are considered. The numerical experiment and the physical analysis of the results for concrete physical models confirmed their efficiency. This class of functions can find wide physical applications in problems of digital signal processing, restoration of images, radar, radiometry, radio astronomy, remote sensing, etc.