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# Amplitude spectrum of a signal of free oscillations of a zone with a defect of 20 mm radius of a cellular panel

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It is proposed to apply the wavelet transform to localize in time the frequency components of the information signals in this article. The wavelet transform allows to fulfil time-frequency analysis of signals, which is very important for studying the structure of a composite material from the mode composition of free oscillations. The proposed appr...

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## Citations

... Streaming data is transmitted between the nodes of the superimposed network along the routes selected by the underlying protocols [19,20]. Controlling the data transmission process will avoid congested areas in the network, increase the throughput and improve the reliability of the network as a whole [2,3,24,43,60,62]. Overlay networks rely on tree and multi-link structures [12,16,71]. ...

Wireless Touch Networks (WTN) have become increasingly important with the emergence of the Internet of Things (IoT) and are regarded as a class of self-organizing networks. This article presents an overview of the construction principles, routing protocols, quality of service parameters, traffic models, and characteristics of WTN. The article also explores the application of dynamic routing protocols for constructing a self-organizing network of autonomous IoT systems. Known dynamic routing protocols for mobile radio networks are reviewed and the advantages and disadvantages of proactive and reactive approaches are discussed.

... coefficients in Hartley bases and cosine functions. Similar results are characteristic in the case of the use of discrete Fourier transforms, Haar and discrete sine transforms [15,16]. The spectral alignment is performed by a signal that is obtained by averaging 500 realizations for each of the sample zones studied. ...

... Systems of linear equations that need to be solved to construct splines are well conditioned, which allows to obtain the coefficients of polynomials with high accuracy. There are many types of interpolation splines [15]. The paper proposes and studies a method for constructing approximations of dependencies of scheduling coefficients on the degree of impact damage using Hermite cubic splines and quadratic splines [21,22]. ...

The article describes the approach to the formation of a simulation model of information signals, which are typical for objects with different types of defects. The dispersive analysis of the signal spectrum components in the bases of the discrete Hartley transform and the discrete cosine transform is carried out. The analysis of the form of the reconstructed information signal is carried out depending on the number of coefficients of the spectral alignment in Hartley bases and cosine functions. The basis of orthogonal functions of a discrete argument is obtained, which can be used for the spectral transformation of information signals of a flaw detector. A method of simulation of information signals has been developed and experimentally investigated, which allows taking into account the deterministic and random components of the characteristics of real information signals. References 24, figures 13, tables 3.

... A significant impact on the results of diagnostics of EM nodes is exerted by their operating conditions and operating modes. So, for aviation applications [28,29], the essential requirement is failure-free operation, that is, a low probability of accidental malfunctions; for power machines [30]-a significant resource, durability. ...

... Therefore, an essential point in diagnosing a particular EM unit is the choice of accelerometer locations. So, for example, in the case of diagnosis of rolling bearings, accelerometers are usually located on bearing shields, and if the state of pressing of a charged magnetic core is diagnosed-on the stator pressure plate [27][28][29][30][31]. ...

Examples of building models and measures in monitoring and diagnostics of electric power objects are given. It is known that accuracy and reliability of results of diagnostics of technical objects depends on many factors. And, not in the last place, from qualitatively formed training sets which on different parameters and characteristics correspond to certain technical conditions of investigated objects. The questions connected with the appearance of some physical processes and their mathematical models accompanying the work of electric power equipment units are considered. The results of mathematical models formation of training sets (measures) which correspond to different technical conditions and modes of robots of the investigated electric power equipment are given. The choice of diagnostic spaces, the coordinates of which are the estimates of parameters or functional characteristics of diagnostic signals, is justified. Known in statistics scattering ellipses are used as learning sets, the boundaries of which with a certain probability cover the data of the results of experiments obtained on real power equipment. A scheme and an algorithm implementing it are proposed, which allow to form learning sets that take into account both possible types of defects in individual nodes of electrical power equipment and their modes of operation (rotor speed of the electric machine, temperature of the diagnosed node, various degrees of electrodynamic and mechanical loading, etc.). This approach allows to use monitoring and diagnostics systems within the Smart Grid technology, which provides the possibility to diagnose power equipment in real time. For building training sets that correspond to both certain types of defects and modes of operation of power equipment units, the results of experimental studies obtained at the laboratory stands of the Institute of Electrodynamics of the National Academy of Sciences of Ukraine were used. As an example of practical application of the proposed models, the problem of constructing solving rules at vibrodiagnostics of rolling bearings of electric machines has been considered.

... Using a digital oscilloscope (FAS) allows to record and save information about the instantaneous values of currents and voltages in three phases of all lines suitable for the substation. Further processing of instantaneous values by the ANFAS device gives the desired set of mode parameters at the measurement point [1][2][3][4][5]. The high information content of this approach for obtaining EMP and the lack of the need for real-time operation make it possible to use new algorithms to determine the LoD that are inaccessible to microprocessor technology [6,7]. ...

... 4. In the absence of an earth SC (Y2 = 0), it can be determined the type of interphase SC and a special phase, if there is a two-phase SC (K (2) ). Checking for asymmetry can be performed with the condition: ...

Automation of damage location is based on the device and a set of algorithms. The device is built on the basis of a digital oscilloscope based on a computer (alarm recording). It allows to record and store information about the instantaneous values of currents and voltages in three phases of all lines suitable for the substation. Further processing of instantaneous values, performed by the device—analyzer of fixed alarms, gives the desired set of mode parameters at the measurement point. The chapter provides a block diagram of the device. The choice of the moment of the beginning and the duration of the emergency analysis interval is described. The section shows the difference between the developed device and analogs. The main advantage of the developed device is the ability to analyze the modes according to secondary informative parameters obtained after processing the instantaneous values of currents and voltages in the interval of analysis of the emergency mode. In this case, it becomes possible to use the criteria for determining the type of short circuit and the special phase. The block diagrams of algorithms of types of short circuits and a special phase are given. Also given the principles by which the location of a short circuit is determined.

... Improving the efficiency of the heat power equipment by increasing the technical level of automatic control systems is possible in two directions: (1) the use of modern technical means (computerized control complexes with high-precision, reliable, lowinertia sensors of technological parameters); (2) improvement of automatic control 1.13 The generalized block diagram of the automatic combustion process control system of a boiler unit (1-setpoint adjuster, 2-regulator, 3-sensor, 4-feedback unit, 5-executing mechanism, 6-regulator) system circuits (as a rule, due to the introduction of additional information signals into the control loop, indicating a change in process parameters, the use of more complex cascade control algorithms [24][25][26][27][28]). ...

The main factors affecting on the efficiency of the boiler are investigated. The influence of the excess air coefficient on the composition of the products of fuel combustion and heat loss with flue gases is analyzed. The necessity of forming a stoichiometric air-fuel mixture to ensure an energy-efficient mode of fuel combustion is shown. The analysis of modern types of burner devices with various types of fuel combustion schemes is carried out. A burner of the PBGM type was selected as a device for conducting experimental studies, which is suitable for use on low and medium power boiler units. The methods for monitoring the composition of the exhaust gases are analyzed. Modern systems for monitoring and controlling the process of fuel combustion in boiler units are considered. Among the main disadvantages of such systems: the availability of sampling and sample preparation systems; lack of frequency regulation of fans and smoke exhausters; long time system installation; a relatively significant payback period; appointments exclusively for large power boilers. The current state of the fleet of boiler units for communal and industrial heat power was studied. It is shown that the majority of small and medium-sized boilers do not meet the specified thermal characteristics, in particular, the efficiency of most boilers does not exceed 70%.

... At the beginning of network operation and formation of a new neuron (in case of a new class formation), corresponding weighted coefficients values are initialized by the initial values: In order to increase efficiency of ART-2 network and clustering reliability, a new network architecture, algorithm for its operation and learning was developed [11]. Figure 3.12 shows the developed ART-2 network structural scheme, where blocks, modified and supplemented in relation to classical ART-2 network, are selected. ...

In this article the methods and algorithms for simulation of noise and rhythm signals in the diagnostic systems are analyzed. Values of theoretical and experimental moments of studied models and their estimates are obtained. Also the realizations of simulated processes (stationary and periodically correlated), their correlation functions estimates and spectral densities estimates are obtained. The general structure of diagnostic systems software are proposed. Software structure of the block of functional load of statistical data processing is realized. The architecture of user interface formation, necessary settings installation, operating modes selection and indication of results are shown for control unit. Features of the use of neural networks in diagnostic systems based on ART-2 are considered.

... There are many systems for diagnosing heating equipment. Some of them are given in [11][12][13][14]. Further thermal imaging of pipelines will be considered. ...

The article presents the causes of defects in pipelines of the centralized heat supply. The possibilities of thermal aerial photography for detecting different types of defects on pipelines in a functioning state are explored. The characteristics and capabilities of the proposed set of devices for monitoring thermal losses in pipelines based on quadrocopters are considered. A method for monitoring the technical condition of pipelines using UAVs is presented. A method for processing thermal images for highlighting anomalous areas is presented. The created hardware-software complex for monitoring the state of trunk pipelines of heat networks based on the UAV is considered. Experiments on the use of UAVs for monitoring heating networks have been conducted. The obtained experimental results, confirming the possibility of differences in the technical condition of pipelines.

Small-aperture transducers based on the magnetostrictive effect for the emission and reception of signals in the ultrasonic range in solid materials have been developed. The article discusses their design features and specifications. Attention is paid to the features of the choice of materials, shapes, and geometrical dimensions of the excitation coil, damper, and magnet. Structural and electrical circuits of the developed transducers are given. Some design and technological solutions have been proposed that can increase the radiation power by 10 times, and resolution by 2-3 times, compared with existing analogs. The area of the radiating part of the sensor is from 0.07 to 0.2 mm 2. Such transducers can be used in various diagnostic systems to detect defects in power equipment, aircraft products, industrial equipment, etc. References 22, figures 10, tables 4.

Examples of using the developed models and measures on the circle for the study of cyclic signals in various subject areas are given. The object of study is the phase shift between cyclic signals. The limiting case of cyclic signals are periodic signals, in particular harmonious signals. The solutions to the problems of precision ultrasonic echo-pulse thickness measurement of products from materials with significant attenuation are considered. A high probability of detecting information signals against additive noise is achieved through the use of selective circular statistics - the resulting vector length. These statistics are determined during processing phase measurement data in a sliding mode. A method for processing the results of multi-scale phase measurements based on numerical systems of residual classes in phase range finders and direction finders is considered. The method is different in that it allows to control the correctness of eliminating the ambiguity of phase measurements. The features of statistical data processing in environmental monitoring systems based on unmanned aerial systems during the flight of objects of increased environmental hazard are analyzed. The given examples testify to the powerful methodological potential of using the developed models and circle measures for use in precision phase measuring systems.

The models and measures for measuring random angular quantities (plane angles and phase shifts of cyclic signals) are considered, the basic concepts, terms, definitions and characteristics that are used in the statistical analysis of angular data are given. The definitions and characteristics of the integral probability distribution function (PDF) of random angles and the density of their distribution are given. A probabilistic model of a random angle on a unit circle is developed. Probabilistic measures of angular quantities are also determined. The most characteristic probability distributions of random angles are analyzed—von Mises, wrapped normal distribution, cardioid, triangular, wrapped Cauchy. The numerical characteristics of random angles are given—the characteristic function, the circular mean, circular dispersion, standard deviation and median. A comparative analysis of the numerical characteristics of random variables and random angles is performed. Definitions and analytical expressions are given for selective circular characteristics—trigonometric moments, mean, resulting vector length, dispersion, etc. The basic information about the models developed by the authors and measures of random phase shifts of cyclic signals for phase measurements are presented.