The paper proposes the method of reduced matrix D-trees, which is an improved version of the method of matrix d-trees. This method is a further development of the application of one of the subcircuit methods, the so-called d-tree method, to the symbolic analysis of linear circuits with constant parameters The method of reduced matrix D-trees, like the d-tree method, provides a significant reduction in the required computer time for modeling circuits, which has a mathematical meaning, consisting in the bringing out of similar terms in the formed complex symbolic expressions. Since there are, in fact, many symbolic terms in such expressions, this reduction in time is due to such factoring. The method is illustrated using a model of a long line consisting of a cascade connection of a large number of elementary links. The results of the computer simulation are also presented.

In this paper on a basis of functional analysis methods we justified theoretically the possibility of different orders root-polynomial functions application for interpolation and approximation of the boundary trajectory of an electron beam in case of its propagation in ionized gas with compensation of the space charge of the beam electrons. It is shown, that the root-polynomial functions satisfy to the second-order differential equation, describing the boundary trajectory of the beam electrons under such physical conditions. The results of interpolation and approximation of the boundary trajectory of the electron beam by root-polynomial functions from the second to the fifth order under the following physical conditions are presented. The interpolation results are compared with the corresponded results of the differential equation solution for the boundary trajectory of the electron beam using Runge-Kutta numerical method of the fourth order. These results are considered as reference ones for the interpolation task. To solve the approximation problem, in this paper an iterative algorithm based on the calculation of both values of the function and its derivatives at reference points is proposed. The approximation task is solved for a sample of numerical data obtained by experimental electron-beam equipment for real processes of current electron-beam technologies, which led to a rather large value of the experimental measurement error due to the effect of random factors associated with thermal treatment of products with electron beam. Test calculations show that the error of interpolation and approximation of numerical data, describing the boundary trajectory of electron beam in case of its propagation in ionized gas, does not exceed a few percent. The theoretical and practical results obtained in this paper are interesting for a wide range of specialists who are engaged in the physics of electron beams, the development of electron-beam technological equipment and implementation of current electron-beam technologies into industry.

In the article, the substantiated proposals for the use of YOLO family neural networks to detect the underwater undetonated munitions are proposed. At the same time, the YOLO3, YOLO4 and YOLO5 neural networks previously trained on the MS COCO dataset are used. The retraining of YOLO3 and YOLO4 neural networks is carried out on the modified Trash-ICRA19 underwater trash dataset, with the number of object classes equal to 13 and 2 of them are fictitious. The average class detection accuracy of 13 object classes using YOLO4 in the mAP50 metric is equal to 75.2 or 88.9% taking into account fictitious classes. The images obtained from video recordings of the demining reservoirs process with the help of remotely operated underwater vehicles (ROV) are used to test neural networks. The improved neural network as a cascade of several serially connected YOLO-segments with multi-pass image processing and tensor-matrix description of the attention mechanism are proposed. The recommendations for further increasing the efficiency of the neural network method of underwater munition selection are developed.

The paper describes methods for obtaining nanocellulose from miscanthus stalks in an environmentally friendly way using the hydrolysis method. The nanocellulose parameters were investigated for applying the nanocellulose in capacitive and resistive humidity sensors. The influence of electrode system parameters and the operating frequency on sensor characteristics was investigated. It was established that the device sensitivity increases with the reduction of distance between electrodes and the operating frequency. Two models of sorption processes at the gas–solid interface were applied, namely, the Freundlich isotherm and Langmuir isotherm, for describing the mechanism of water adsorption by nanocellulose-based humidity sensors. The long-term operation stability of such devices was also investigated.

The Dowell and Ferreira calculation methods for the loss resistance of choke windings are analyzed in this paper. We determine that the neglect of the winding geometry influence is the cause of their error, because the problem is solved on a plane. The influence of winding geometrical parameters on current distribution in conductors is investigated for verification. The influence of single layer winding geometry on loss resistance for conductors of different diameters is considered. It is determined that the influence of winding geometry on the loss resistance is significant (up to 40%), and it increases with increasing conductor diameter and frequency, and decreasing coil diameter. There is non-uniformity in current distribution of coiled into a ring conductor caused by proximity effect. The influence of inter-winding distance for a single layer winding on its loss resistance is studied. The influence of interturn proximity effect is significant and increases with decreasing inter-winding distance. The reason for discrepancy with known methods is the non-uniformity of current distribution in the outer and inner turns. The peculiarities of current distribution in square cross-section conductors and equivalent in area cylindrical conductors presented as straight single conductors, single turns, and single layer windings are considered. The influence of the conductor shape on current distribution and its density are determined.

In this paper, the time of solving such SSLAR was reduced by using one of subcircuit methods, namely, topological d-tree method. The existing d-tree method is used for circuits with constant parameters; therefore, this paper proposes its modification under the name Matrix d-tree method that is extended to circuits with variable parameters. This involves the use of the notion of parametric matrix model y = 1/r, g = 1/L, and C of variables and constant elements of parametric circuit. The d-tree method, both ordinary and matrix, provide a near-optimal taking out of similar terms in formed expressions. This result in a significant reduction of time required for their formation, decrease of the memory size required and the high operation speed of symbolic d-tree method as a whole. This leads to a significant extension of circuits admissible for analysis in terms of their complexity. The analysis of simulation of periodically time-variable ladder circuits presented in this paper has shown a significant increase of admissible complexity of circuits using the matrix d-tree method as compared with the use of standard tools of MATLAB. This fact makes it possible to materially extend the application scope of FS-method in problems of statistical investigations or optimization of electronic devices that are simulated by linear periodically time-variable circuits.

Users in the common corner of a three-cell downlink multi-user MIMO system suffer from low signal strength from their own cell as well as equal strength interference signal from their neighbour two cells. The schemes for interference mitigation are adopted to improve system sum-rate performance in this scenario. Further, the full CSI feedback by users to their base station puts high burden on the reverse feedback channel. Quantized reduced channel information feedback with interference alignment technique and suitable precoding can reduce the burden on the reverse channel as well as they can improve the system sum-rates. The LTE code book based precoding techniques provide improvements in the sum-rate. We design precoding using singular value decomposition (SVD) on the selected code vectors based on maximization of Equivalent Channel-Code vector (SVD-ECC) and maximization of SINR-Code vector (SVD-SINRC). Both these techniques show system sum-rate improvement over ZF based precoding technique, SVD-ECC providing more improvements than SVD-SINRC. We also experiment with users with orthogonal equivalent channels and the subsequent SVD on the selected users channel (SVD-ORT). We show results varying user SNR, number of selected user K and the total number of active user L in a cell.

The paper proposes a method for estimating the speed of broadband Internet access using information transmission systems (ITS) via xDSL technology and utilizing the vectoring system of crosstalk compensation between ITS when operating via access networks. The estimation accounts for additive interference, uncompensated crosstalk between interdependent ITS caused by using the vectoring system. The attainable access speed using the G.fast protocol was estimated depending on specifications of transmission lines, the number of ITS in operation, and the use of vectoring system.

The problem of object perimeter protection by human steps detection using autonomous seismic activity sensors is solved in this paper. The results of the CME (consecutive mean excision) and FCME (forward consecutive mean excision) algorithms to calculate these sensors threshold level are presented. The algorithms are tested on real experimental data. The number of false alarms for CME and FCME algorithms is equal to 23% 10%, respectively, operating with the envelope of seismic signal. The possibilities to reduce the number of false alarms for algorithms are explored. The signal trend neutralization allows us to reduce the probability of false alarms to 16% and 7% for the CME and FCME algorithms, respectively. The signal amplitude normalization in the analysis interval makes it possible to reduce the number of false alarms to a negligible value. The results allow us to choose the algorithm depending on the input data specifics. The CME algorithm with preliminary normalization of the signal amplitude is the most appropriate to solve the problem of human steps detection by autonomous sensor due to less computational complexity.

This paper addresses the problem of displacement measurement by a three-probe implementation of microwave interferometry in cases where the reflection coefficients of the object under measurement (target) and the antenna are comparable. The paper presents a three-probe displacement measurement method that accounts for the antenna reflection coefficient. In this method, the target displacement is determined from two quadrature signals using a phase unwrapping technique. The expressions for the quadrature signals include the unknown magnitude of the target reflection coefficient. To determine this quantity, an equation that relates it to the detector currents and the antenna reflection coefficient is derived. It is shown that the magnitude of the target reflection coefficient is given by the smaller positive root of this equation provided that the sum of the target and the antenna reflection coefficient magnitudes is no greater than one. Because of the smallness of the antenna reflection coefficient, this condition is almost always met in free-space measurements. To verify the proposed method, determining the displacement of a target executing a sine vibratory motion was simulated. The simulation showed that if the target and the antenna reflection coefficients are comparable, the method offers a several-fold reduction in the displacement determination error in comparison with the case where the antenna reflection coefficient is ignored even in the presence of a marked noise component in the detector currents. The proposed method may be used in the development of microwave displacement sensors.