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Showing papers by "Volga State University of Water Transport published in 2019"


Journal ArticleDOI
08 Oct 2019-Chaos
TL;DR: A simple piecewise-smooth model which switches between three three-dimensional linear systems that yield a singular hyperbolic attractor whose structure and bifurcations are similar to those of the celebrated Lorenz attractor is constructed.
Abstract: Chaotic attractors appear in various physical and biological models; however, rigorous proofs of their existence and bifurcations are rare. In this paper, we construct a simple piecewise-smooth model which switches between three three-dimensional linear systems that yield a singular hyperbolic attractor whose structure and bifurcations are similar to those of the celebrated Lorenz attractor. Due to integrability of the linear systems composing the model, we derive a Poincare return map to rigorously prove the existence of the Lorenz-type attractor and explicitly characterize bifurcations that lead to its birth, structural changes, and disappearance. In particular, we analytically calculate a bifurcation curve explicit in the model's parameters that corresponds to the formation of homoclinic orbits of a saddle, often referred to as a "homoclinic butterfly." We explicitly indicate the system's parameters that yield a bifurcation of two heteroclinic orbits connecting the saddle fixed point and two symmetrical saddle periodic orbits that gives birth to the chaotic attractor as in the Lorenz system. These analytical tasks are out of reach for the original nonintegrable Lorenz system. Our approach to designing piecewise-smooth dynamical systems with a predefined chaotic attractor and exact solutions may open the door to the synthesis and rigorous analysis of hyperbolic attractors.

23 citations


Journal ArticleDOI
TL;DR: In this paper, a simplified model of the particle transport in an evaporating droplet with a contact line pinned to a hydrophilic substrate was developed, which allows us to perform computer simulations of the particles transport.
Abstract: A simplified model is developed, which allows us to perform computer simulations of the particles transport in an evaporating droplet with a contact line pinned to a hydrophilic substrate. The model accounts for advection in the droplet, diffusion, and particle attraction by capillary forces. On the basis of the simulations, we analyze the physical mechanisms of forming of individual chains of particles inside the annular sediment. The parameters chosen correspond to the experiments of Park and Moon [Langmuir 22, 3506 (2006)LANGD50743-746310.1021/la053450j], where an annular deposition and snakelike chains of colloid particles have been identified. The annular sediment is formed by advection and diffusion transport. We find that the close packing of the particles in the sediment is possible if the evaporation time exceeds the characteristic time of diffusion-based ordering. We show that the chains are formed by the end of the evaporation process due to capillary attraction of particles in the region bounded by a fixing radius, where the local droplet height is comparable to the particle size. At the beginning of the evaporation, the annular deposition is shown to expand faster than the fixing radius moves. However, by the end of the process, the fixing radius rapidly outreaches the expanding inner front of the ring. The snakelike chains are formed at this final stage when the fixing radius moves toward the symmetry axis.

13 citations


Book ChapterDOI
23 May 2019
TL;DR: Analysis of scientific literature on the processes of informatization of social space shows that the categorical apparatus that determines the essence of the information society remains not yet fully developed, and researchers can not clearly dissociate such concepts as “social reality’ and “virtual reality”.
Abstract: Relevance. In conditions of modern development of information in society, the problem of studying processes of informatization of social space becomes relevant for the methodology of philosophical, humanitarian and social knowledge. However, as shown by analysis of scientific literature on this issue, the categorical apparatus that determines the essence of the information society remains not yet fully developed. In particular, both in foreign and domestic scientific literature introduced the concepts of “virtualization”, “virtual reality” and “internetization”. However, introduced concepts do not have their own clear meaning, which leads to the identification of concepts “social” and “virtual”. As a result, when analyzing the processes of Internet social space, researchers can not clearly dissociate such concepts as “social reality” and “virtual reality”.

8 citations



Journal ArticleDOI
TL;DR: In this paper, the temperature dependence of microwave absorption in powders of various metal oxides was studied and the results obtained may be of both fundamental and applied interest for researchers engaged in microwave heating of materials.
Abstract: In this paper, the temperature dependence of microwave absorption in powders of various metal oxides was studied. The powders of aluminum oxide Al2O3, zinc oxide ZnO, tungsten trioxide WO3, and titanium dioxide TiO2 were the test substances. A subterahertz gyrotron setup with a frequency of 263 GHz and an adjustable output power level from watts to 1 kW was used as a radiation source. In the experiments, the samples of the powders were heated by the radiation of the gyrotron, and at the same time, the temperature of the sample was recorded and the power absorbed in the sample was measured by the calorimetric method. The measurements were carried out in a wide range of temperatures: from several tens up to 1200 °C. The results obtained may be of both fundamental and applied interest for researchers engaged in microwave heating of materials.

6 citations


Journal ArticleDOI
30 Dec 2019
TL;DR: In this paper, the authors consider blinking systems, i.e., the systems randomly changing its structure in each sequential fixed period of time, and find ghost attractors which arise in a blinking system being unexpectively different with respect to the attractors of composing systems.
Abstract: In this paper we consider blinking systems, i.e. the systems randomly changing its structure in each sequential fixed period of time. Our goal is to find ghost attractors which arise in a blinking system being unexpectively different with respect to the attractors of composing systems. We study two blinking systems. One of them is a nonlinear rotator with switching torque and another is a blinking piecewise-linear Lorenz-type system. We prove the existence of ghost attractors in both cases for certain parameter ranges.

4 citations


Journal ArticleDOI
TL;DR: In this article, the results of the first experiments demonstrating the possibility of wireless data transmission using a subterahertz band gyrotron signal as a carrier were presented, where the output power of the gyroscope was modulated by a rapid change in the potential of the currentless anode, and the resulting amplitude modulated (AM) signal with the medium power of about 50 W was received by the ultrafast THz detector.
Abstract: This paper presents the results of the first experiments demonstrating the possibility of wireless data transmission using a subterahertz band gyrotron signal as a carrier. The output power of the subterahertz gyrotron was modulated by a rapid change in the potential of the currentless anode. The resulting amplitude modulated (AM) signal with the medium power of about 50 W was received by the ultrafast THz detector. Successful transmission of an analog sound signal and transmission of a digital signal at a rate up to 1.5 Mbps over a distance of about 2 m was demonstrated. The investigated approach confirms its potential for data transmission using gyrotron in any frequency band without loss of generality.

4 citations


Journal ArticleDOI
TL;DR: In this paper, a mathematical model describing the viscoplastic deformation and damage accumulation in polycrystalline structural alloys in creep was developed using the equations of the mechanics of damaged media.
Abstract: The main regularities of the degradation of structural materials (metals and alloys) resulting in a decrease in creep-rupture strength were investigated. A mathematical model describing the viscoplastic deformation and damage accumulation in polycrystalline structural alloys in creep was developed using the equations of the mechanics of damaged media. The paper presents the results of experimental studies of the short-term creep of 12Kh18N9 steel and VZh-159 high-temperature alloy at constant temperature and different stresses set in the samples and the results of experimental studies of creep recovery in some structural steels. Deformation and damage accumulation were studied numerically and the results were compared with the data of full-scale experiments.

2 citations


Journal ArticleDOI
TL;DR: In this paper, a mathematical model is developed, which describes processes of plastic deformation and fatigue damage accumulation in polycrystalline structural alloys under a combined effect of low and high-cycle fatigue.
Abstract: Processes of fatigue life of polycrystalline structural alloys under a combined effect of low- and high-cycle fatigue are considered. In the framework of mechanics of damaged media (MDM), a mathematical model is developed, which describes processes of plastic deformation and fatigue damage accumulation. The MDM model consists of three interrelated parts: relations defining cyclic elastoplastic behavior of the material, accounting for its dependence on the failure process; equations describing fatigue damage accumulation kinetics; a strength criterion of the damaged material. The version of defining relations of elastoplasticity is based on the notion of yield surface and the principle of orthogonality of the plastic strain rate vector to the yield surface at the loading point. This version of equations of state reflects the main effects of the cyclic plastic deformation process of the material for arbitrarily complex loading trajectories. The version of kinetic equations of damage accumulation is based on introducing a scalar parameter of damage degree. The construction uses energy-based principles and accounts for the main effects of the process of nucleation, growth and merging of microdefects under arbitrarily complex multiaxial loading regimes. A combined form of the evolutionary equation of fatigue damage accumulation in the regions of low-cycle (LCF) and high-cycle (HCF) fatigue is proposed. It is shown that, under regular cyclic loading of the material, the stress amplitude of the cycle decreases by degrees during the transition from LCF to HCF and depends on the physical interaction of these mechanisms in the transition zone. The condition when the damage degree attains its critical value is taken as the strength criterion of the damaged material. A methodology of numerically determining parameters of the evolutionary equation of fatigue damage accumulation in the conditions of HCF is presented. To assess the reliability and the limits of applicability of the defining relations of MDM, processes of plastic deformation and fatigue damage accumulation in a number of structural alloys in cyclic tests have been numerically studied, and the obtained numerical results have been compared with the data of full-scale experiments. The results of comparison of the numerical and experimental data reveal that the developed model of mechanics of damaged media adequately describes durability of structures subjected to a combined effect of low- and high-cycle fatigue mechanisms. It is shown that the introduced MDM model qualitatively and, accurately enough for practical engineering purposes, quantitatively describes the main effects of the processes of plastic deformation and fatigue damage accumulation in structural alloys under cyclic loading.

1 citations


Journal ArticleDOI
25 Aug 2019
TL;DR: In this paper, an algorithm for smooth control of the rotational speed of the internal combustion engine using the setting mechanism of suspend mode was proposed. And the proposed algorithm (gradient descent method) is borrowed from the neural network technologies and allows calculating the rotation frequency of the engine shaft corresponding to the minimum specific fuel consumption when operating at the current fractional load.
Abstract: The variants of transformerless power topologies of ship diesel generator sets of variable rotational speed are considered. A power circuit of a diesel generator set of variable rotational speed on the basis of an active voltage rectifier and a buffer energy store, which has the highest efficiency in terms of weight and size and performance, is proposed. A block diagram of a control system for semiconductor converters as part of a diesel generator set of variable rotational speed is presented. The control system of the active voltage rectifier is implemented upon the principle of regulation according to the position of the generalized voltage vector of the network. In order to increase the energy efficiency of the inverter diesel generator set there has been developed the algorithm for smooth control of the rotational speed of the internal combustion engine using setting mechanism of suspend mode. The proposed algorithm (gradient descent method) is borrowed from the neural network technologies and allows calculating the rotation frequency of the internal combustion engine shaft corresponding to the minimum specific fuel consumption when operating at the current fractional load. In MatLab Simulink computer environment a simulation model of a variable-frequency diesel generator set based on active voltage rectifier was developed and transients were studied. The results of simulation modeling of the dynamic modes of the load switching have been presented, taking into account its size and nature; the indicators of the specific fuel consumption of the internal combustion engine as part of a diesel generator set of variable rotational speed are presented, as well. Using a variable-speed diesel generator set based on an active voltage rectifier has been proved to allow ensuring the required quality indicators of the generated electricity when the internal combustion engine is operating at lower energy-efficient rotation frequencies in the fractional load mode.

1 citations


Proceedings ArticleDOI
14 Oct 2019
TL;DR: In this paper, a series of laboratory experiments was carried out, in which the structure of average flows in the water column created by bubble flows with different gas flow rates was obtained.
Abstract: One of the urgent problems of gas pipeline transport today is the detection of gas leaks in underwater sections of gas pipelines and reducing their negative impact on the environment. This paper is devoted to the development of remote detection methods of gas leaks from underwater gas pipelines by images of slicks above them. A series of laboratory experiments was carried out, in which the structure of average flows in the water column created by bubble flows with different gas flow rates was obtained. The simulation of surfactant removal to the water surface by bubbles was performed by adding sodium dodecyl sulfate (SDS) to the laboratory cuvette at the concentration of 0.5 mg/l. For the surfactant film on the water surface, experimental dependences of its characteristics on the operation time of the "bubble pump", such as the surface tension coefficient, elasticity and the relative damping coefficient of small- scale waves under the film, were obtained. It was shown that there are flow convergence zones at some distance from the gas outlet area, which vary depending on the intensity of the gas flow. Surfactant film samples taken in these areas confirmed that over time, the accumulation of surfactants occurs on the water surface. Field experiment conducted in one of the backwaters of the Oka river in the city of Nizhny Novgorod allowed to spot and evaluate the size and shape of the film slick formed around the gas outlet area. The conducted experiments confirmed the formation of a surfactant film spot near the removal area, which indicates the possibility of its remote detection in full-scale conditions, provided the wind near water surface is not more than 2-10 m/s. The obtained data made it possible to get a general idea of the morphology and characteristics of the surfactant spot around the gas outlet from the water.

Proceedings ArticleDOI
01 Jul 2019
TL;DR: The main results contain the new method for operational management establishing, taking into account nonlinear distortions in communication channels, which satisfies the modern requirements for its use in the systems of dynamic allocation of frequency resources.
Abstract: In this article is considered the problem of operational frequency management in terms of its dynamic use, taking into account non-linear distortion in high cascades transceivers. Main results contain the new method for operational management establishing, taking into account nonlinear distortions in communication channels. This method satisfies the modern requirements for its use in the systems of dynamic allocation of frequency resources. The method improves the use of communication channels efficiency.

Journal ArticleDOI
TL;DR: The saturation magnetization of single-crystalline garnet ferrite films of different compositions is calculated on the basis of the familiar relations of the Neel model on the sublattice structure of ferrimagnetic compounds.
Abstract: The saturation magnetization of single-crystalline garnet ferrite films of different compositions is calculated on the basis of the familiar relations of the Neel model on the sublattice structure of ferrimagnetic compounds. Other parameters of the films are calculated using the theory of strip domains and the stability theory of cylindrical magnetic domains. The presented material is educational and intended for use in practical exercises in the study of magnetism. The problem is given to students of specialties 22.03.01, Materials Science and Materials Technology (when studying the discipline of Physics of Magnetic Materials); 03.03.02, Physics (when studying the disciplines of General Physics, in the section on Electricity and Magnetism and the disciplines of the Magnetic Properties of Matter); and to students of specialty 13.03.02, Electric Power Engineering and Electrical Engineering (when studying the discipline of Magnetic Measurements) at Astrakhan State University.

Proceedings ArticleDOI
14 Oct 2019
TL;DR: In this paper, the authors present some new results on the Volga/Oka rivers confluence based on both in situ measurements of hydrological characteristics in the mixing zone and on satellite observations.
Abstract: River confluence is a ubiquitous phenomenon which plays an important role in river dynamics, mixing processes, pollution transport etc. It can be often visually observed that two converging rivers continue to flow as two parallel weakly mixing streams separated by a relatively thin transition region – a mixing zone (MZ), which can reach out for some distance downstream the junction apex. A typical example of a river confluence is the merging of the Volga and Oka rivers (Russia). This paper presents some new results on the Volga/Oka rivers confluence based on both ‘in situ’ measurements of hydrological characteristics in the MZ and on satellite observations. During the ‘in situ’ measurements a large set of data regarding velocity fields, chlorophyll-a concentration, water temperature, turbidity, parameters of organic surface films etc. was obtained. It is found that significant differences between the hydrological characteristics of the Volga and Oka flows are observed at sufficiently large distances downstream the junction apex (about 10 river widths or more); and the mixing zone remains quite narrow. Film sampling and further analysis of the surfactant films in the MZ were carried out. It is shown that the surface tension decreases and the film elasticity grows in the foam/slick bands separating the Volga and Oka flows thus indicating the increased concentration of surfactants in the bands. Satellite images of the Volga-Oka MZ are collected indicating that the confluence area is clearly seen in satellite optical imagery (MSI Sentinel-2 satellite) due to strong difference in color between the flows. The radar imagery shows the mixing zone in the form of a slick/foam band (SAR Sentinel-1) which manifests on the water surface due to enhanced damping of short wind waves.

Journal ArticleDOI
01 Jan 2019
TL;DR: In this paper, a model of the A. Smith economic person and its analysis is presented, which is a tool for describing and searching for a consensus of people interests employed in the field of industrial relations, outside whose development it is impossible to talk about enriching the nation both then and today.
Abstract: The paper presents a model of the A. Smith economic person and its analysis. The relevance of the study and the author’s interest in the topic is dictated by the desire to contribute in the development of a promising tool for studying the economic behavior of individuals of the economic person concept, as well as the absence, especially in Russia, of works devoted to examining A. Smith’s work from the angle of his teachings about economic person. The purpose of the work is to identify and show the features of A. Smith economic model. The main part of the study presents the basic principles that determine the approach of A. Smith to an economic person. In the section, the results of the study disclose the content of the A. Smith economic model. The characteristic is given to each of the elements developing this model. The specific features of A. Smith economic model are highlighted. The conclusions section provides a general description of A. Smith economic model. It emphasizes its qualitative difference from other, later models of an economic person, which stems from the dominance of an ethical and anthropic component, which implies the priority of the public good over individual gain. In the conclusion section, a result is drawn about the underestimated potential of A. Smith’s model about an economic person, which is a tool for describing and searching for a consensus of people interests employed in the field of industrial relations, outside whose development it is impossible to talk about enriching the nation both then and today.

Journal ArticleDOI
01 Feb 2019
TL;DR: The suggested model of loads calculation allows to improve accuracy of Load calculation, affecting the pipe-layer during the technological process which, in its turn, allows both to select appropriate vehicles for linear pipeline section repair and to increase operational safety by forecasting possible conditions of pipe-layers rollover.
Abstract: This article is devoted to modelling results of pipe-layers loading during the major overhaul of main pipeline linear sections. Basic loads affecting the pipe-layer in operation are considered in this research. The results obtained prove that at the major overhaul of the main pipeline linear section, efforts of hoisting the pipe constitute only 60% of overall process duty, 20-40% are variable and depend on the weight of technological vehicles in operation. The suggested model of loads calculation allows to improve accuracy of loads calculation, affecting the pipe-layer during the technological process which, in its turn, allows both to select appropriate vehicles for linear pipeline section repair and to increase operational safety by forecasting possible conditions of pipe-layers rollover.