Радиотехника и электроника

Abstract—The editing problem in clustering (deletion and addition of edges and/or vertices in an initial graph for building a cluster structure), including various options of the problem (edge cluster editing, vertex cluster editing, etc.) is studied. A literature survey on the problems (problem types and solving approaches) is presented. The cluster edge editing problem is in focus. Several mathematical optimization models for the problem are described: (i) the basic edge editing problem with minimization of the general number of added edges and the number of deleted edges, (ii) the option of the above-mentioned problem with weights of all vertex pairs (including the bi-criteria problem case), and (iii) a multi-criteria problem with vector weights of the vertex pairs. In addition, some other editing problems are briefly described: (a) the edge deletion editing problem, (b) edge editing problem with several vertex types, and (c) vertex deletion editing problem. The problems discussed are illustrated by numerical examples. Some future research directions are pointed out.

Abstract—An estimation problem distributionally robust with respect to random noise is considered for a signal with the bounded second-order derivative on a finite number of observations. The objective functional is the probability that the L2-norm of the estimation error will exceed a pre-specified threshold. Its worst-case value on the set of all signals with the bounded second-order derivative and arbitrary distributions of the noise vector with fixed mean and covariance is to be minimized over the finite-dimensional class of spline estimators. The optimization problem is solved using the methods of convex programming by representing the objective functional in terms of the mean square bound following Markov’s inequality and the tight bound in the form of the multivariate Selberg inequality. A numerical experiment is carried out to compare the obtained solutions to the problem of restoration of the trajectory of a target with bounded acceleration.

Abstract—Problems of image smoothing and segmentation are among the most important directions of processing and analysis of video information, which have much in common in their formulation, final goals, and solution methods. The similarities and differences of the problems are shown on the base of the image model using the analysis and comparison of known smoothing and segmentation algorithms.

Abstract

A comprehensive approach to the analysis of electroencephalographic (EEG) signals obtained from human brain and artificially synthesized using machine learning methods is presented. The main focus is on data preprocessing, including signal normalization and filtering, as well as application of various feature extraction methods, in particular, Fast Fourier Transform and Mel-Frequency Cepstral Coefficients. A comparative analysis of classification accuracy using logistic regression, random forest, gradient boosting, and recurrent neural network LSTM is performed. Special attention is given to the effect of filtering parameters on classification accuracy. The results show that filtering and proper tuning of model parameters significantly improve the accuracy of EEG signal classification, ensuring separation of real and synthetic EEG pools. The results and discussion may serve as a basis for further research in the field of biomedical signal analysis and processing.

Abstract

The process of forming edge metallization on input windows (germanium, silicon, and other discs) used for introducing the received light flux into a photodetector housed in a protective hermetic casing is being investigated. This work presents the results of an experimental study on the dependence of the edge metallization profile of Ge discs, formed by magnetron sputtering, on the design parameters of the loading device. Various designs of loading devices are presented. The experimental results demonstrate the influence of thickness on the edge metallization profiles of the components of the loading device that mask the discs during sputtering.

Abstract

Methods to solve the problem of traceability and reproducibility for the measurement of parameters of second-generation photodetectors are proposed. An improved block diagram of the measurement methods and division into groups of the methods for measurement of second-generation photodetector devices and monitoring of auxiliary equipment is presented.

Abstract

Effect of illumination distribution in the circle of confusion on the measurement of the photoelectric coupling coefficient of the second-generation photodetector devices is studied. A theoretical study is carried out using mathematical modeling for illumination patterns of different structure and several ratios of photodetector pitch to the effective size of the photosensitive area. A formula is derived for calculation of the photoelectric coupling coefficient for a known distribution of photodetector sensitivity. The main conditions that affect the reliability of the results on the simulated measurement process are presented.

Abstract

Distributions of dark currents, lifetimes of minority carrier, and microdefects revealed by selective etching are compared. The main reason for increased dark currents and decreased photosensitivity in silicon photodiodes fabricated on n-type silicon using the Czochralski method are the generation–recombination processes on fine oxide precipitates.

Abstract

The results of the development of a recursive algorithm for temporal noise reduction with an adaptive threshold for thermal imaging systems are presented. This algorithm is designed to reduce the level of temporal noise based on the results of analyzing a sequence of images obtained using a thermal imaging channel. A mathematical model of the algorithm is provided, as well as the required amount of computing resources needed for its hardware implementation in field programmable gate arrays (FPGAs). Several characteristics of the thermal imaging system with the developed algorithm were measured and conclusions were made about the positive influence of the algorithm on its noise equivalent temperature difference (NETD).

Abstract

The resonant scattering spectra by the main magnetic mode of a subwavelength linear structure consisting of two dielectric flat thin rings located along the wave vector and excited by the displacement currents of the incident plane electromagnetic wave of the microwave range are investigated experimentally and using computer modeling. As distinct from a single ring, splitting of the resonant frequency is observed in the scattering spectra of the magnetic field in the far wave zone, near wave zone, and near the centers of the rings. The measured spectra coincide with the spectra resulting from computer calculations at all measurement points.

Abstract

For the task of Earth remote sensing (ERS) in the short-wave infrared (IR) range of the spectrum, the most promising are matrix and multi-row photodetector modules of the short-wave infrared (IR) range of the spectrum based on heteroepitaxial structures of materials of the ternary solution of cadmium-mercury-tellurium (HgCdTe) and the ternary solution of indium-gallium-arsenide (InGaAs), sensitive in the spectral range from 1 to 2.5 μm. Possible architectures of photosensitive elements that provide reduced dark currents and noise are analyzed. Ways of improvement are considered and dark currents and parameters of n-on-p-type heterostructures based on HgCdTe in a wide temperature range, as well as the parameters of p+-B–n-N+-type barrier structures based on InGaAs are investigated.

Abstract

An overview of various sensor designs for recording the parameters of microparticles in the accelerator path is provided, which are used to simulate the impact of micrometeoroids and space debris particles on structural elements of a spacecraft. A model of a cylindrical induction sensor (a Faraday cup) and a possible modification of its design for measuring the microparticle distribution in the accelerator path are considered in more detail.

Abstract

The parameters of photodetectors based on photosensitive barrier structures and photodiodes with absorbing layers of InAs1–xSbx and In1–xGaxSb ternary solutions of the mid-wave infrared spectrum range are studied. Temperature dependences of lifetime and dark current in InAs1–xSbx and In1–xGaxSb layers have been calculated. The signal-to-noise ratio in the operating temperature range was determined. Parameter modeling has shown that for photodetectors based on InAs0.8Sb0.2 with a cutoff wavelength λ0.5 ∼ 4.8 µm the detectability at T = 100 K will be D* ≈ 1012 cm W–1 Hz1/2; for photodiodes based on In0.7Ga0.3Sb with cutoff wavelength λ0.5 ∼ 5.2 µm the detectability at T = 100 K will be D* ≈ 1011 cm W–1 Hz1/2, which is suitable for high temperature applications.

Abstract

A new deselection method has been developed for detecting defects in infrared photomodules (IR PMs) with time delay and accumulation mode (TDM). The developed method is used to detect and deselect defective photosensitive elements (PSEs), which most reduce the signal-to-noise ratio (SNR) in IR PM channels. This method increases the SNR of IR PM channels, which improves the ability of IR PMs to detect low-power infrared optical signals. This result is ensured by the fact that the detection of defective PSEs is achieved by processing the signals and noise of all PSEs using the detection criterion of PSEs that most reduce the SNR of the IR PM channels. This method is a general rule for detecting defective PSEs, since the criterion analyzes the influence of all PSEs on the SNR of IR PM channels, including the noisiest elements.

Abstract

The electric field on the surface of a metal electrode immersed in plasma with an electron temperature of Te ∼ 10 eV and plasma density ne from 1010 to 1013 cm−3 has been calculated under negative electric potential Ψ0 of the electrode and large values of parameter |eΨ0|/Te  \( \gg \)  1. The obtained asymptotic formula for the field strength at |eΨ0|/Te  \( \gg \)   1 differs significantly from the classical formulas for calculating the electric field and the Debye length of field screening near the electrode surface in plasma, which are valid under condition |eΨ0|/Te  \( \ll \)  1. It has been shown that, at |eΨ0|/Te  \( \gg \)  1, near the electrode in a plasma, a modified Debye layer can exceed the classical Debye length by two orders of magnitude. To calculate the electric field on the electrode surface in plasma, a generalized formula has been proposed in the explicit form, which is valid in a wide range of parameter 0 < |eΨ0|/Te < 104 at negative electrode potentials of up to 10 kV.

Abstract

The electrostatic reflection method is formulated and proven for a point charge located near a plane-layered medium consisting of two films on a dielectric half-space. The method is generalized to the case of an arbitrary system of charges and is used to solve mathematically similar problems of electrostatics and the stationary thermal conductivity of plane-layered media. The problem of finding the electrostatic potential distributions around a conducting sphere located near a plane-layered structure consisting of two dielectric films on a dielectric half-space is solved. Solutions to similar problems of finding the temperature distribution of uniformly heated bodies located near a heat-conducting plane-layered structure of two heat-conducting films on a heat-conducting half-space are discussed.

An Erratum to this paper has been published: https://doi.org/10.1134/S1064226924550023

An Erratum to this paper has been published: https://doi.org/10.1134/S106422692456002X

An Erratum to this paper has been published: https://doi.org/10.1134/S1064226924570014

An Erratum to this paper has been published: https://doi.org/10.1134/S1064226924560018