On the Results of a Special Experiment on the Registration of Traveling Ionospheric Disturbances by a System of Synchronously Operating Chirp Ionosondes

We present the results of observations of traveling ionospheric disturbances (TIDs) based on the data of the operation of the network of chirp oblique sounding stations of the ionosphere on 18–19 December 2019. For observations, four stations of the same type located in Vasilsursk (56.3° N; 46.08° E), Yoshkar-Ola (56.62° N; 47.87° E), Kazan (55.8° N; 49.12° E), and Nizhny Novgorod (56.32° N; 44.02° E) were used. They formed six synchronous sounding paths with lengths from 120 km to 320 km. The registration of the amplitude-frequency and distance-frequency characteristics (AFC and DFC) by the chirp oblique sounding stations was carried out every minute. Additionally, two vertical sounding stations of the ionosphere as ionosondes CADI and Cyclone (Vasilsursk and Kazan) were used. The passage of several types of TIDs has been observed. Based on the measurements of the DFC of the ionosphere, as obtained on different paths by simultaneously operated chirp stations, and ionograms obtained by vertical ionosondes, estimates of the spatial dimensions and TID velocity were made, and their direction was identified.

Analysis of the frequency characteristics of the control system for the processes of fuel supply to the cylinders of the power unit

The idea of monitoring the identity of the cylinder capacities of an internal combustion engine under conditions of incomplete information is proposed and a computer system is built on its basis. The signal of the instantaneous rotation speed of the crankshaft of the power unit was used as input information. In the development of the hardware architecture, injectors with piezoelectric actuators, the principle of direct digital control, and the principle of control with feedback on the state of fluctuations of the crankshaft rotation speed were used. The Laplace transform was used as a mathematical apparatus for analyzing the structural diagram of a computer system for programmed control of the processes of supplying fuel and air to the cylinders of the power unit. Mathematical models of the components of the hardware for controlling the processes of supplying the fuel-air mixture were constructed, and as a result of the analysis of the structural diagram of the computer system, the transfer function was obtained. Using the capabilities of the Matlab software environment, the transient and impulse transient characteristics of the system are obtained, the Nyquist hodograph is constructed, and the logarithmic amplitude-frequency characteristics of the hardware are established. It was found that the frequency characteristics of the mathematical model of a computer system have the necessary dynamic characteristics. Using the method of expansion into simple fractions, an expression is obtained for a discrete transfer function, the coefficients of the power polynomials of which are established using the method of determinants and computational capabilities of the Mathcad software environment. On the basis of a discrete transfer function, a scheme for computer modeling of the process of processing the signal of the instantaneous speed of rotation of the crankshaft by hardware is constructed. The output signal was obtained by computer simulation, as a result of the analysis of which the speed of the hardware for processing the input information was established.

Optimizing the Design of Surface-Acoustic-Wave Ring Resonator by Changing the Interdigitated Transducer Topology

Introduction. Previous works considered the frequency characteristics and methods for fixing sensitive elements in the form of a wave ring resonator on surface acoustic waves in a housing made of various materials, as well as the influence of external factors on sensitive elements. It was found that the passband in such a case is sufficiently wide, which can affect adversely signal detection when measuring acceleration using the sensitive element under development. Therefore, it has become relevant to reduce the sensitive element’s bandwidth by changing the design of the interdigitated transducer (IDT).Aim. To demonstrate an optimal topology for an IDT with a low bandwidth, leading to improved signal detection when acceleration affects the sensitive element.Materials and methods. The finite element method and mathematical processing in AutoCAD and in COMSOL Multiphysics.Results. Nine topologies of IDT are proposed. All these types were investigated using the COMSOL Multiphysics software on lithium niobate substrates, which material acts as a sensitive element. The frequency characteristics are presented. The data obtained allowed an optimal design of the ring resonator to be proposed: an IDT with rectangular pins without selective withdrawal.Conclusion. Self-generation in a ring resonator can be performed by withdrawing no more than one pair of IDTs for 10 or more periods. In this case, the withdrawal of IDTs should be uniform. With an increase in the number of IDT withdrawals, the geometry of the ring resonator is violated, and the wave leaves the structure. The presence of a shared bus keeps the surface acoustic wave inside the IDT structure, and the narrowing of the periods towards the inner part of the structure makes it possible to improve the frequency characteristics of the ring resonator on surface acoustic waves.

Parametrical Synthesis of Radio Devices with the Set Quantity of Identical Cascades for Inclusion Variants of Jet Two-port Networks between a Nonlinear Part and Loading

Introduction. The ability to analytically determine some parameters of various radio devices, which are optimal according to the criterion of providing the set values of the modules and phases of transfer functions at the required number of frequencies, significantly reduces the time for numerical optimization of the rest of the parameters according to the criterion of forming the required frequency response and frequency response in the frequency band. Until now, such problems with respect to radio devices have been solved only for one stage of the "nonlinear part – matching device" or "matching device – nonlinear part" type. As a matching device, reactive, resistive, complex, or mixed quad-poles were used.Aim. Development of algorithms for parametric synthesis of radio devices with an arbitrary number of identical cascades of the "nonlinear part – matching reactive quadrupole" type according to the criterion of ensuring the specified frequency characteristics. Non-linear parts are represented as a non-linear element and parallel or serial current or voltage feedback.Materials and methods. Four-pole theory, matrix algebra, decomposition method, method of synthesis of microwave control devices, numerical optimization methods.Results. Systems of algebraic equations are formed and solved. Models of optimal quadrupole conductors are obtained in the form of mathematical expressions for determining the relationships between the elements of their classical transmission matrix and for finding the frequency dependences of the resistances of two-pole conductors.Conclusion. It is shown that the frequency characteristics of the studied radio devices from the same stages are identical or similar to the frequency characteristics of radio devices from the same stage, but with the signal source and load resistances changed in a certain way. Such schemes are called equivalent. A comparative analysis of the theoretical results (frequency response and frequency response of radio devices) obtained by mathematical modeling in the "MathCad" system, and the experimental results obtained by circuit modeling in the "OrCAD" and "MicroCap" systems, shows their satisfactory agreement.

Piezoelectric Sensing Element-Assisted Ceramic Art Process Optimization and Visual Quantitative Characterization

In this paper, piezoelectric sensing elements are used to assist in the study and analysis of ceramic art process optimization and visual quantization characteristics. A series piezoelectric element impedance sensor is designed based on the resonant frequency characteristics of the series piezoelectric element. Combining the resonant frequency characteristics of the series piezoelectric element and the basic principle of the impedance method, a multisensing impedance method based on the series piezoelectric element impedance sensor is proposed. The feasibility of the multisensing impedance method for monitoring the grout compactness was verified experimentally, and the basic principle of the method was further investigated by finite element simulation. The vase-type porcelain vessels were classified according to symmetry elements to find the characteristic points, the abdominal morphology was used as the basis for classification, and the screened samples were extracted from the contours to exclude the influence of other factors on the vessel shape. By the symmetrical elements of each type of ware, the classification principle of the ware type was designed and divided into six types, and each type was further subdivided into various types to establish a typological map of Qing dynasty bottle porcelain. The information entropy redundancy that describes the uniformity of the code appearance probability and the visual redundancy that describes the human eye’s sensitivity to image content or details are all entry points that can be considered for image coding. The experimental results show that the LBP-HOG fusion features can digitally express the information of ancient ceramic ornamentation and dig and verify the evolution of ceramic ornamentation with the times from the digital quantity. The GRNN model has an excellent performance in processing small samples of ancient ceramic data.

Towards dynamic property control of bridge spans

Regulation of the dynamic properties of bridge spans is a priority field of this research, which solves the problem of increasing the obsolescence and physical periods of bridge structures manifested both at the design stage of the load redistribution in the load bearing and during long-term operation.Over the past 40 years, technical bridge diagnostics has shown that the durability and safe long-term operation can be ensured by the improved calculations, operation and stress and strain control under the excess and over-calculated live loads.The aim of this work is to control the dynamic deformation and amplitude-frequency characteristics of bridge spans under harmonic random (non-stationary) oscillations of the span-vehicle system due to changes in the energy and stress state of the structure. The dynamic behavior of the span-vehicle system is based on the control for the amplitude-frequency characteristics of random oscillations by averaged values, the required spectral density being provided.The use of dynamic dampers for the system element control and the rigidity of junctions provide antiphase oscillations of the bridge span elements such as beams and decks, that leads to the unaccounted inertial forces.Another important element of the joint work imbalance of the bridge span elements during the dynamic load, are various defects, both in the deck design and load-bearing elements. It is assumed that the deck is a transfer layer (element) of vibrations induced by a vehicle in the beams. It is shown that the control for the dynamic properties is required in the case of a coincidence between the vehicle and beam stiffness and mass at the center of the system rigidity.The attention is paid to the conditions and dependencies between the dynamic load parameters and the stress-strain state of the bridge beams at the elastic and elastoplastic stages, with respect to the additional inertia of the system. This approach is the pilot in the Russian and foreign bridge construction in terms of experimental studies and testing of bridges for continuous random traffic.The dynamic testing of bridge spans for random traffic flow contributes to the creation of vibration diagnostic express laboratories necessary for the operation and maintenance of bridges.

DEVELOPMENT OF BEHAVIORAL MODEL FOR SWITCHING VOLTAGE REGULATOR MICROCIRCUIT 1290EF1

The issue of developing a behavioral model of pulse voltage converter IC is considered on the example of a microcircuit of domestic production 1290EF1. In order to verify the adequacy of the model, taking into account its frequency characteristics, recommendations and basic requirements are given when performing a full-scale and numerical experiment to determine the frequency characteristics of such type of nonlinear dynamic objects.

OBTAINING CONDITIONS FOR TECHNOLOGY NEUTRALITY OF COMMUNICATION SYSTEMS WITH MINIMUM COUPLING LOSS METHOD

Background. Technology neutrality is widely used in frequency bands, where communication systems are evolving, but there are strict restrictions on the parameters and deployment of base stations of different technologies using adjacent channels. Ways to mitigate this effect have not been sufficiently studied and require further analysis and development. Objective. The purpose of this article is to investigate the methodology for obtaining technical conditions of technological neutrality with minimum coupling loss method to determine the value of additional filtering requirements and present the results of practical implementation of this technique. Methods. The method of detailed power analysis of frequency characteristics of filters for base stations’ transmitter and receiver is applied. Results. The article presents the results of obtaining minimal guard band and additional filtering requirements in the adjacent channels of transmitter and receiver belonging to different technologies. Examples of practical implementation of the minimum guard band and frequency characteristics of additional filters are given. Conclusions. The general method of determining the technical conditions for ensuring technology neutrality is presented and the value of the minimal required guard band between the adjacent transmitter and receiver channels is obtained.