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Today, the analysis and synthesis methods of electro-pneumatic systems with position control actuated by pneumatic artificial muscles (PAMs) are quite well known. In these methods, pneumatic artificial muscle is considered as an object with lumped parameters. However, the PAM is an object with distributed parameters, where the pressure, density, and mass flow rate of gas are varied along the bladder length. Thus, in the case of certain design parameters of the pneumatic artificial muscle and certain frequencies of the supply pressure, resonant gas oscillations affected by the wave processes in the bladder may occur. Thereby, in the PWM-driven PAM-actuated system, certain operation frequencies of the control pneumatic valve can cause oscillations of gas in the bladder and in the connected pipeline. These processes could lead to vibrations of the executive device. To solve this practical problem, a distributed parameter model of the PAM that takes into account the pressure fluctuations in the bladder and in the pipeline was elaborated. Also, in this work, a new method in which the wave processes are described by ordinary differential equations instead of partial differential equations was proposed. [ABSTRACT FROM AUTHOR]

A fundamentally new possibility of obtaining additional information about the state of objects and processes of the subject area is considered. It is shown that wave processes can be investigated and analyzed through additional information obtained from the parameters of the functioning of the hardware elements of a computer information system. A method of revealing wave processes in a computer system is described. Experiments confirm the possibility of obtaining and using additional information from a secondary source for the information system to perform its regular functions. [ABSTRACT FROM AUTHOR]

The thermal processes involved in the recrystallization within porous ultrapure iron compacts heated after cold pressing in a steel die were experimentally studied. The temperatures of recrystallization stages were shown to correspond to the heating behavior of metals and alloys. Depending on the heating rate of compacted powdered iron, various types of thermokinetic behavior were identified, indicating the nonlinear nature of interactions within the deformed powder body. Stages with both nonlinear and linear thermal behavior were present, as evidenced by the competition between several processes leading to the emergence of wave-like transfer of energy, accumulated while powdered iron deformed during cold pressing. The thermokinetic patterns observed in the heating of compacts, especially those made of pure iron, allowed all stages of relaxation in the deformed metal to be identified. The temperature profile in the heating process generally reflects the thermal state of the powdered metal, influenced by the additional release of energy accumulated in deformation. At some stages, heat release led to nonlinear processes, resulting in the occurrence of thermal waves. Both asynchronous and synchronous temperature changes were observed. In asynchronous behavior, nonlinear waves emerged. The superposition of relaxation processes in the generation of thermal waves is possible. At specific heating rates, the maximum amount of energy is simultaneously released in the relaxation and recrystallization processes, as testified by an increase in temperature to 550°C. The relaxation processes involve less energy compared to the recrystallization processes and the transition to the annealed state. In addition, after complete recrystallization, the onset of the sintering process was observed under temperature oscillations with damping. [ABSTRACT FROM AUTHOR]

The paper considers the problem of unsteady wave propagation in the cross section of an infinite hollow cylinder made of a viscoelastic functionally graded material with nonmonotonically varying properties along the radius. The cylinder is replaced by a piecewise-homogeneous one with a large number of coaxial homogeneous layers approximating the properties of the source material. Based on the previously constructed solution for a layered cylinder, wave processes in a cylinder made of a viscoelastic functionally graded material with different types of nonmonotonic inhomogeneities are studied. [ABSTRACT FROM AUTHOR]

The thermal processes of recrystallization in porous copper compacts heated after cold pressing in a steel die were experimentally studied. The recrystallization stages, with temperatures corresponding to data determined with metallographic and other research methods, were identified. Only the first tempering stage was found to occur uniformly throughout the entire volume at a heating temperature of 190°C. Upon further heating, a linear stage ensued, where the temperature remained consistent throughout the entire volume of the material, persisting until the next stage. This was accompanied with energy release, as confirmed by a zero temperature gradient across all regions within the sample. With an increase in temperature to 210–215°C, a thermal surge was observed and visible temperature asynchronization was noted in individual volumes of the sample. However, this was followed by a temperature gradient between individual volumes. At this stage, asynchronized thermal behavior within the sample was observed for the first time, as evidenced by the emergence of thermal waves. Subsequent stages demonstrated nonlinear thermal behavior, evidenced by several competing processes leading to the wave-like transfer of energy accumulated as the copper powders deformed during cold pressing. Like recrystallization processes with first-order reactions in the high-temperature synthesis of intermetallic and other compounds, the emergence of thermal waves was due to several competing processes. Thus, if microplastic deformation processes occurred during recrystallization, then traveling waves could arise in the system, which was actually revealed. This could lead to thermal interference and subsequently to local buildup of thermal energy, potentially causing a sharp increase in temperature in individual areas of the wires deformed during switching and, as a result, their ignition. The temperature surges observed were likely to cause the combustion of insulating materials. Therefore, this can explain the causes of accidents that occur in the operation of complex mechanisms with numerous electrical circuits. [ABSTRACT FROM AUTHOR]

2023 marks the 25th anniversary of the formation of the Department of Nonlinear Physics of Saratov State University. The department has developed and implements training programs on the general course of physics, physics of nonlinear processes, physics of wave processes in magnetic fields and structures.

The present numerical study is aimed at revealing the influence of the nozzle exit-to-resonator edge distance on the gas-dynamic characteristics of the acoustic-convective flow in the flow path of a bichannel system. The aim of the work is the development of a computational technology for describing physical processes in the duct of multichannel systems that generate high-intensity acoustic fields. Five configurations of the bichannel system in which the gap between the nozzle exit and the resonator edge was 0.85, 1.10, 1.35, 1.60, and 1.85 of the resonator diameter, were analyzed. As a result of the study, a complete picture of the gas-dynamic flow formed in the duct of the bichannel system was obtained, including the resonating cavity and the region in between the nozzle and resonator. With the help of numerical simulation, the formation of a flow with high-frequency, low-amplitude oscillations at a small gap between the nozzle exit and the resonator edge, which was observed in experiments, has been demonstrated. Pure-tone oscillations with maximum intensity occur when the resonator is placed in the region of the beginning of the second barrel, this observation being in good agreement with the data obtained by other authors. Subsequent increase in the nozzle-to-resonator distance leads to the emergence of subharmonics and multiple harmonics. Verification of gained numerical results with available experimental data is carried out. [ABSTRACT FROM AUTHOR]

Youm, C.I.; Morales, J.A.; Doumbouya, M.F.; Garcia-Villalba, E.; Sow, I.S., and Sow, E., 2023. Dynamics, evolution, and facies preservation of a microtidal chenier plain, Joal-Fadiouth (Senegal, West Africa). Journal of Coastal Research, 39(2), 257–265. Charlotte (North Carolina), ISSN 0749-0208. Cheniers are coarse sediment ridges formed above finer sediments deposited on a tidal flat, the origin and development of which have traditionally been attributed to storm waves. Joal-Fadiouth is a microtidal system located on the southern coast of Senegal (West Africa). This system presents a succession of sandy and shelly ridges displaying a facies architecture consistent with a chenier plain facies model. This study combines aerial orthophotographs and sediment cores to interpret the sedimentary dynamics and facies of the chenier plain under analysis. The genesis of the last active chenier is related to the arrival of sand from the frontal ebb-tidal delta. Breaching processes occurred in the ebb delta, inducing the abandonment of the frontal lobe by the ebb-tidal currents. Fair-weather waves rework the sand from the frontal lobe, causing a migration of the sand in a manner similar to the formation of a typical nearshore swash bar. In Joal-Fadiouth, these bars soar and migrate over a tidal flat through the action of normal waves during spring high tides. Relict cheniers present shelly gravel sediments coarser than those observed in active cheniers. Thus, the final stage of stabilization of cheniers was attributed to the action of more energetic storm waves. The cheniers that accumulate during the action of ordinary and continuous processes tend not to persist, and only the coarsest cheniers formed during high-energy events finally remain in the sedimentary record. In addition to discussing the preservation of active coastal forms, this work is of regional interest, given that so far there has been only one work on cheniers in West Africa since 1989. [ABSTRACT FROM AUTHOR]

The article presents the results of processing non-emergency pressure measurements that are transmitted via the SCADA hardware and software system to the control center of the main gas pipeline. SCADA is widely used for real-time control of the modes of gas transmission systems. However, the data provided by SCADA contain some information that is not fully analyzed. The performed processing of pressure measurements is a passive experiment aimed at a deeper understanding of the flow processes that occur during the flow of gas in industrial pipelines of high power. As a result of the experiment, four types of wave phenomena were found: single waves of (a) compression and (b) decompression that were both damped as they moved along the pipe, (c) oscillations with an amplitude and frequency practically unchanged in a fixed section within a period of about 2 h, and (d) wave phenomena with a sharply changing amplitude and frequency within a period of several minutes. The characteristics of wave processes, such as the speed of movement and the decreasing or attenuating amplitude of oscillations, were evaluated. For evaluation, models were built that take into account the specifics of information transfer procedures, namely, SCADA's representation of continuous functions in a discrete form. The results obtained can be used as an additional tool for searching for leaks, such as in fistulas and unauthorized tie-ins, allowing us to more accurately separate the useful signal from the noise. The question is raised about the adequacy of the one-dimensional model for describing the flow processes in the zones of large gradients of regime parameters. The reasons for possible inadequacy and ways to overcome it are indicated. [ABSTRACT FROM AUTHOR]

Transient wave processes in viscoelastic structures built from functionally graded material (FGM) still remain almost unexplored. In this article, the problem of the propagation of nonstationary longitudinal waves in an infinite viscoelastic layer of a FGM with plane–parallel boundaries is considered. The physical and mechanical parameters of the FGM depend continuously on the transverse coordinate, while the wave process propagates along the same coordinate. The viscoelastic properties of the material are taken into account employing the linear integral Boltzmann–Volterra relations. The viscoelastic layer of the FGM is replaced by a piecewise-homogeneous layer consisting of a large number of sub-layers (a package of homogeneous layers), thus approximating the continuous inhomogeneity of the FGM. A solution of a non-stationary dynamic problem for a piecewise-homogeneous layer is constructed and, using a specific example, the convergence of the results with an increase in the number of sub-layers in the approximating piecewise-homogeneous layer is shown. Furthermore, the problem of the propagation of nonstationary longitudinal waves in the cross section of an infinitely long viscoelastic hollow FGM cylinder, whose material properties continuously change along the radius, is also considered. The cylinder composed of the FGM is replaced by a piecewise-homogeneous one, consisting of a large number of coaxial layers, for which the solution of the non-stationary dynamic problem is constructed. For both the layer and the cylinder composed of a viscoelastic FGM, the results of calculating the characteristic parameters of the wave processes for the various initial data are presented. The influence of the viscosity and inhomogeneity of the material on the dynamic processes is demonstrated. [ABSTRACT FROM AUTHOR]

Today, the exact determination of the parameters of the fracturing of oil and gas fields is of great practical importance. Therefore, an important role is played by computer modeling of the seismic responses from cracks, which correspond to fractured zones actually occurring in nature in terms of the distribution of fracture lengths, positions and rotation angles. Thus, the development of an algorithm aimed at solving this problem plays an important role. In this paper, we have presented the developed algorithm for the placement of cracks in a fractured zone with given geological parameters, such as distribution of lengths, opening, angle of inclination of cracks. The application of this algorithm makes it possible to use in further calculations a geological fractured zone model that is as close as possible to real oil and gas-filled reservoirs. The paper presents the results of test calculations using the grid-characteristic computational method to model wave field scattered on the fractured zone. [ABSTRACT FROM AUTHOR]

The results of experimental research into the influence of the geometry of the flow part of the working chamber and the pressure at the inlet and outlet of a vortex-type generator on the intensity and character of nonlinear wave and hydrodynamic processes, the flow pattern, and the magnitude and nature of distribution of pressure in the generator chamber are presented. [ABSTRACT FROM AUTHOR]

Earlier, the authors formulated and proved interval and point criteria for the existence of moving singular points of a third-degree nonlinear differential equation with a polynomial seventh-degree right-hand side for a real domain. For the complex domain, these criteria are associated with specificity of transition to phase spaces. Necessary as well as necessary and sufficient conditions for the existence of moving singular points are obtained. The results of these studies are the basis of the algorithm for obtaining moving singular points of nonlinear differential equations in the complex domain. The results of this paper allow us to expand the classes of the studied nonlinear differential equations with moving peculiarities. [ABSTRACT FROM AUTHOR]

The paper considers the specifics of nonlinear differential equations that have applications in different areas. Earlier, the authors proved the existence and uniqueness theorem for a solution to a class of non-linear differential equations in a neighborhood of a moving singular point. In this paper, we consider the first problem of studying a third-order nonlinear differential equation in the domain of analyticity. An analytical approximate solution is built, taking into account the solution search area. A priori estimates of the analytical approximate solution are obtained, and the technology of their optimization using a posteriori ones is illustrated. The result of a numerical experiment is presented. The presented results allow to expand the class of nonlinear differential equations for describing various phenomena and processes. [ABSTRACT FROM AUTHOR]

This research belongs to the field of rock physics. In recent years, in solid state physics and materials science, new knowledge has emerged about microplastic strain of various materials, including rocks. These data were obtained using high-precision micro- and nanoscale strain measurements. The very fact of the existence of the poorly studied rock property in the earth sciences requires the study of the possible influence of the rock microplasticity on the propagation of seismic and acoustic waves. The studies were carried out using three alternative methods and under different observation conditions. The field measurements were carried out in the zone of low velocities in crosshole space with transmitted waves of frequency of 240–850 Hz. The laboratory measurements were carried out on sandstone samples with transmitted (6.8 kHz) and reflected (1 MHz) waves at the strain of 10−8–10−6. The manifestations of microplasticity were recorded using high-resolution recording of signals with discretization time tdiscret = 1 μs – 40 μs and 32.5 ns. The wave amplitude variation was provided in a closed cycle: discrete increasing the amplitude from minimum to maximum and return to the initial value (A1+ → A2+ → … Amax … → А2– → A1–). In this amplitude range, an amplitude hysteresis was observed, a sign of which was the inequality of wave velocities on the upward and downward amplitude courses. This effect was recorded for all three measurement methods at different frequencies. However, the amplitude hysteresis of the wave velocity was not observed only in the measurements at full water saturation of loam. The largest amplitude-dependent change in the wave velocity reached 2% (at the accuracy of 0.02%), and the change in the attenuation value amounted to 5%. The reason for this effect could be microplastic inelasticity, which manifested itself by amplitude plateaus located within the waveform. The amplitude microhysteresis forms overall picture of the amplitude dependence of the wave velocity in wide amplitude range. Proposals for the potential use of the obtained data for solving some applied problems have been presented.

Synchronization of traveling waves in two rings of FitzHugh–Nagumo neurons is studied. Coupling between neurons within each ring is dissipative, while one between rings is memristive. Complete synchronization of waves in identical rings in the presence of an initial phase shift between wave processes and partial synchronization of waves in the case of different coupling strengths inside the rings are considered. The influence of the initial states of memristive coupling on the synchronization of wave processes in the case of memristors with an infinitely long memory and with the forgetting effect is investigated.

While wave processes on shore platforms have been recently advanced by a number of field‐based studies, few attention has been paid to the role of bed roughness on wave dissipation and wave setup dynamics in these environments. This study reports on a new field experiment conducted under storm wave conditions on a gently sloping shore platform which was instrumented from 10 m water depth up to the shoreline. Data analyses are complemented with numerical simulations performed with a 3D fully coupled modeling system using a vortex force formalism to represent the effects of short waves on the mean circulation. An accurate representation of wave dissipation by both depth‐induced breaking and bottom friction is found essential to reproduce the transformation of short waves across the platform and the resulting wave setup. Wave energy dissipation by bottom friction is dominant in the subtidal part of the platform and contributes to about 40% of the total wave energy dissipation. The enhanced wave bottom friction on the platform decreases the wave height before breaking, which reduces the contribution of wave forces to the wave setup compared to a smooth bottom (mechanism 1). Conversely, an idealized analysis of the cross‐shore momentum balance reveals that the wave‐induced circulation increases the wave setup, this process being enhanced on a rough bottom (mechanism 2). The contribution of mechanism 2 increases with the bottom slope, accounting for up to 26% of the wave setup for a 1:20 sloping shore platform, and overcoming mechanism 1. Plain Language Summary: In the nearshore, the dissipation of short waves controls the mean circulation by generating currents but also a rise of the mean water level along the shoreline, a process known as the wave setup. Waves and wave‐induced processes on shore platforms can be different from that on sandy beaches, principally due to a higher bed roughness. This study reports on a new field experiment conducted under storm wave conditions (short waves reaching 6 m at 50 m depth) on a gently sloping shore platform which was instrumented from 10 m water depth up to the shoreline. Data analyses are complemented with numerical simulations performed with a three‐dimensional modeling system coupling a wave and circulation models. The results show that wave bottom friction occurring on the platform explains 40% of the total wave energy dissipation, which reduces the contribution of wave dissipation to the wave setup (mechanism 1). Conversely, further analysis reveals that depth‐varying currents forced by waves increase the wave setup, the rough bottom making this mechanism stronger (mechanism 2). Mechanism 2 counteracts mechanism 1 and becomes even dominant as the bottom slope increases, accounting for up to 26% of the wave setup for a 1:20 sloping shore platform. Key Points: A new field data set collected during storm wave conditions on a shore platform instrumented from 10 m water depth up to the shorelineWave bottom friction explains about 40% of the total wave energy dissipation across the shore platform and reduces the wave setupThe contribution of the wave‐induced circulation to the wave setup is enhanced on the rough bottom and increases with the bed slope [ABSTRACT FROM AUTHOR]

Copyright of Agricultural Engineering is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The results of numerical simulation of gas-dynamic flow in the channel of a technical device with a resonant cavity are presented. One period of gas-dynamic loading of structural elements of the resonant cavity has been studied in detail. A complete picture of pressure and temperature field distribution along the resonant cavity channel has been obtained. The maximum and minimum values of pressure and temperature, achieved when the gas flow moves along the resonator channel, have been determined. [ABSTRACT FROM AUTHOR]

The article presents the results of processing non-emergency pressure measurements that are transmitted via the SCADA hardware and software system to the control center of the main gas pipeline. SCADA is widely used for real-time control of the modes of gas transmission systems. However, the data provided by SCADA contain some information that is not fully analyzed. The performed processing of pressure measurements is a passive experiment aimed at a deeper understanding of the flow processes that occur during the flow of gas in industrial pipelines of high power. As a result of the experiment, four types of wave phenomena were found: single waves of (a) compression and (b) decompression that were both damped as they moved along the pipe, (c) oscillations with an amplitude and frequency practically unchanged in a fixed section within a period of about 2 h, and (d) wave phenomena with a sharply changing amplitude and frequency within a period of several minutes. The characteristics of wave processes, such as the speed of movement and the decreasing or attenuating amplitude of oscillations, were evaluated. For evaluation, models were built that take into account the specifics of information transfer procedures, namely, SCADA’s representation of continuous functions in a discrete form. The results obtained can be used as an additional tool for searching for leaks, such as in fistulas and unauthorized tie-ins, allowing us to more accurately separate the useful signal from the noise. The question is raised about the adequacy of the one-dimensional model for describing the flow processes in the zones of large gradients of regime parameters. The reasons for possible inadequacy and ways to overcome it are indicated.

Transient wave processes in viscoelastic structures built from functionally graded material (FGM) still remain almost unexplored. In this article, the problem of the propagation of nonstationary longitudinal waves in an infinite viscoelastic layer of a FGM with plane–parallel boundaries is considered. The physical and mechanical parameters of the FGM depend continuously on the transverse coordinate, while the wave process propagates along the same coordinate. The viscoelastic properties of the material are taken into account employing the linear integral Boltzmann–Volterra relations. The viscoelastic layer of the FGM is replaced by a piecewise-homogeneous layer consisting of a large number of sub-layers (a package of homogeneous layers), thus approximating the continuous inhomogeneity of the FGM. A solution of a non-stationary dynamic problem for a piecewise-homogeneous layer is constructed and, using a specific example, the convergence of the results with an increase in the number of sub-layers in the approximating piecewise-homogeneous layer is shown. Furthermore, the problem of the propagation of nonstationary longitudinal waves in the cross section of an infinitely long viscoelastic hollow FGM cylinder, whose material properties continuously change along the radius, is also considered. The cylinder composed of the FGM is replaced by a piecewise-homogeneous one, consisting of a large number of coaxial layers, for which the solution of the non-stationary dynamic problem is constructed. For both the layer and the cylinder composed of a viscoelastic FGM, the results of calculating the characteristic parameters of the wave processes for the various initial data are presented. The influence of the viscosity and inhomogeneity of the material on the dynamic processes is demonstrated.

The study discusses an electrical device (appliance) that determines the location of damage to the insulation material and power cable line sheaths in 6 – 20-kV distribution networks. The proposed device can determine the localization of any types of faults (FLs) with a high transition resistance at the insulation failure (floating breakdown) site with an accuracy of at least 0.2% of the total cable length. The device can determine the location of damage to the insulation of a controlled cable line during the high-voltage tests of about 10,000-m long single- and three-phase cable lines without changing the test scheme or needing additional connecting devices, while excluding the labor-intensive process of "burning" the insulation. The device can improve the reliability of operation of the integrated power grid, reduce the time of emergency and restoration work in distribution networks, and extract additional economic benefits by reducing the undersupply of energy. [ABSTRACT FROM AUTHOR]

Coastal depositional systems are commonly classified in terms of the relative interaction of wave, tide and fluvial processes. The La Anita Formation represents the opportunity to study and better understand coastal sedimentary systems. It is a poorly studied prograding siliciclastic deltaic-coastal wedge accumulated in the Campanian during the foreland stage of the Austral-Magallanes Basin. A detailed depositional process-based facies analysis have allowed the definition of 13 sedimentary facies and 9 facies associations for the La Anita Formation, ranging from prodelta to interdistributary delta-channel deposits. According to the spatial distribution of these facies associations, the La Anita Formation was divided into two informal units bounded by a regional erosion surface. The lower unit shows abundant hummocky cross-bedded and bioturbated sandstones, coarsening-upward trends and mainly aggradational to progradational vertical stacking pattern, and it was interpreted as a wave-dominated fluvial-influenced delta. The upper unit is characterized by unidirectional dune cross-bedding, coarsening-upward trend and a progradational vertical stacking pattern, and was interpreted as a fluvio-dominated delta with no evidence of tide or wave influence. These two units represent two genetically unrelated depositional sequences bounded by a regional erosion surface, which is interpreted as a sequence boundary triggered by a relative sea-level fall. The lower unit is part of a progradational highstand systems tract which involves the underlying deep-marine Alta Vista Formation. The upper unit deposits reflect a complete relative sea-level cycle which includes an undifferentiated lowstand and transgressive systems tracts and, toward the top, highstand systems tract.

Earlier, the authors formulated and proved interval and point criteria for the existence of moving singular points of a third-degree nonlinear differential equation with a polynomial seventh-degree right-hand side for a real domain. For the complex domain, these criteria are associated with specificity of transition to phase spaces. Necessary as well as necessary and sufficient conditions for the existence of moving singular points are obtained. The results of these studies are the basis of the algorithm for obtaining moving singular points of nonlinear differential equations in the complex domain. The results of this paper allow us to expand the classes of the studied nonlinear differential equations with moving peculiarities.

A diffuse-interface method for simulating wave fields in saturated elastic porous media is addressed. Wave processes are described by a hyperbolic system of first-order differential equations derived from the theory of thermodynamically consistent systems of conservation laws of continuum mechanics. This unified system of governing equations provides a universal way for the simulation of wave fields in rock samples with sharp interfaces between layers with different elastic/poroelastic petrophysical properties. A good qualitative agreement of numerical calculations with the classical theory of elasticity and Biot's model is shown. [ABSTRACT FROM AUTHOR]

The paper considers the specifics of nonlinear differential equations that have applications in different areas. Earlier, the authors proved the existence and uniqueness theorem for a solution to a class of non-linear differential equations in a neighborhood of a moving singular point. In this paper, we consider the first problem of studying a third-order nonlinear differential equation in the domain of analyticity. An analytical approximate solution is built, taking into account the solution search area. A priori estimates of the analytical approximate solution are obtained, and the technology of their optimization using a posteriori ones is illustrated. The result of a numerical experiment is presented. The presented results allow to expand the class of nonlinear differential equations for describing various phenomena and processes.

This paper presents the results of experimental studies of the influence of the geometry of the flow part of the chamber and the pressure at the inlet and outlet of the vortex-type generator on the intensity and nature of the occurrence of nonlinear wave and hydrodynamic processes. [ABSTRACT FROM AUTHOR]

Copyright of Technical Electrodynamics / Tekhnichna Elektrodynamika is the property of National Academy of Sciences of Ukraine, Institute of Electrodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Relevance of the work is caused by the need of localize the defects of the transformer windings at diagnosis. It is possible to determine the spatial location of the defects along the transformer winding only if the transformer is considered as a system with distributed parameters. The main aim of the study is to present the transformer winding in the form of distributed electric circuit and to study the transients of such a circuit in two cases, at grounded winding end and at open winding end; to determine primary and steady voltage distribution along the transformer windings at the grounded winding end and open winding end; to search for possible ways to overcome the overvoltage arising along the transformer winding. The aim of the work is to obtain as well the transitional function caused by a unit action, in order to use subsequently the Duhamel integral which allows obtaining the transients in the transformer winding at an arbitrary external action. The methods used in the study are based on equations solution in partial derivatives using Laplace transform and transfer functions. It uses the initial conditions along the transformer winding and the boundary conditions at the ends of the windings. The final solution of partial differential equations is represented as a series, that is in the form of wave superposition with different frequencies. The results. The obtained transfer function of the voltage distribution along transformer windings allows determining: primary and steady stress distribution; over-voltage transient conditions; optimal values of distributed capacitance, and minimizing overvoltage along the winding.

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The problem of establishing the temperature profile in a radiatively cooling-down disperse flow in the presence of external thermal radiation is considered. A comparison of the obtained analytical estimates of the speed of establishment of an equilibrium profile with the results of numerical solution is made. The amplitude of the wave phenomena accompanying the establishment of temperature has been calculated. [ABSTRACT FROM AUTHOR]

The process of wave propagation in a two-layer media is studied numerically using a model of nonlinear liquid three-component medium. The cases of cylindrical and spherical symmetries are considered. For description of wave propagation, the equations of continuum mechanics are used. The propagation of a pressure wave in the radial direction in a two-layer soil medium is described. The results are analyzed depending on layer parameters for both cases of symmetry. [ABSTRACT FROM AUTHOR]

The article gives information on the impact of the process of highland seepage from the base of the Shamkir water reservoir. The method of determining the consequences of seepage on the coastal slopes of the Shamkir HES is studied in the article. In the article the scheme of probable layer- by-layer slip of the geological section of the soil massif of the left bank slope of the Shamkir reservoir is determined, two ways of stability of the slopes of natural rocks with different stratified deposits and rocks with artificially deposited layers were calculated. [ABSTRACT FROM AUTHOR]