Formation Of Dissipative Structures Research Articles

Hybrid Patterns and Solitonic Frequency Combs in Non-Hermitian Kerr Cavities.

We unveil a new scenario for the formation of dissipative localized structures in nonlinear systems. Commonly, the formation of such structures arises from the connection of a homogeneous steady state with either another homogeneous solution or a pattern. Both scenarios, typically found in cavities with normal and anomalous dispersion, respectively, exhibit unique fingerprints and particular features that characterize their behavior. However, we show that the introduction of a periodic non-Hermitian modulation in Kerr cavities hybridizes the two established soliton formation mechanisms, embodying the particular fingerprints of both. In the resulting novel scenario, the stationary states acquire a dual behavior, playing the role that was unambiguously attributed to either homogeneous states or patterns. These fundamental findings have profound practical implications for frequency comb generation, introducing unprecedented reversible mechanisms for real-time manipulation.

Evolution of current- and pressure-driven instabilities in relativistic jets

ABSTRACT Instabilities in relativistic magnetized jets are thought to be deeply connected to their energy dissipation properties and to the consequent acceleration of the non-thermal emitting relativistic particles. Instabilities lead to the development of small-scale dissipative structures, in which magnetic energy is converted in other forms. In this paper we present three-dimensional numerical simulations of the instability evolution in highly magnetized plasma columns, considering different kinds of equilibria. In fact, the hoop stresses related to the azimuthal component of magnetic field can be balanced either by the magnetic pressure gradient (force-free equilibria, FF) or by the thermal pressure gradient (pressure-balanced equilibria, PB) or by a combination of the two. FF equilibria are prone to current-driven instabilities (CDI), while PB equilibria are prone to pressure-driven instabilities (PDI). We perform a global linear stability analysis, from which we derive the different instability properties in the two regimes, showing that PDI have larger growth rates and are also unstable for high wavenumbers. The numerical simulations of the non-linear instability evolution show similar phases of evolution in which the formation of strong current sheets is followed by a turbulent quasi-steady state. PDI are however characterized by a faster evolution, by the formation of smaller scale dissipative structures and larger magnetic energy dissipation.

Mechanisms of formation of wear-resistant dissipative structures in non-stationary lubrication conditions

The work aimed to determine the influence of the processes of supramolecular self-organization in the lubricating layer on the patterns of wear of friction pairs. The mechanisms of structural adaptability of tribocoupler elements were analyzed, and the regularities of the manifestation of a large-scale and energy jump, which characterizes the transition of the tribosystem to a metastable state, were determined. An evaluation of the tribotechnical characteristics of commercial transmission oils was carried out on a software-hardware complex that, using a roller analogy, simulates the operation of gears in conditions of rolling with slipping. It was established that the activation of contact surfaces in the mode of frequent starts and stops leads to active interaction of the lubricant's components and the metal's surface layers with the gradual formation of boundary adsorption layers. For transmission oil 'Bora B' T-Shyp, an increase in anti-friction properties has been established due to the effective lubricating ability of the oil when forming the hydro- and non-hydrodynamic components of the lubricating layer thickness. The effect of the chemical activity of the zinc dialkyl dithiophosphate antiwear additive and the hydrocarbon components of the base of transmission oils on the effectiveness of the formation of boundary films is considered. It was determined that the formation of stable boundary films of the lubricant is the leading process in manifesting their damping properties concerning the localization of elastic-plastic deformation along the depth of the metal. When boundary films are formed on 90-95% of the contact area, the change in the microstructure of the near-surface layers is fixed at a depth of up to 20 microns; when boundary films are formed on 20...50% of the surface area, the spread of elastic-plastic deformation reaches a depth of up to 50 microns. The kinetics of the formation of boundary films by the lubricant and the indicators of the specific work of friction in contact are correlated with the intensity of wear of the contact surfaces

The Conditions Necessary for the Formation of Dissipative Structures in Tribo-Films on Friction Surfaces That Decrease the Wear Rate.

Tribo-films form on surfaces as a result of friction and wear. The wear rate is dependent on the frictional processes, which develop within these tribo-films. Physical-chemical processes with negative entropy production enhance reduction in the wear rate. Such processes intensively develop once self-organization with dissipative structure formation is initiated. This process leads to significant wear rate reduction. Self-organization can only occur after the system loses thermodynamic stability. This article investigates the behavior of entropy production that results in the loss of thermodynamic stability in order to establish the prevalence of friction modes required for self-organization. Tribo-films with dissipative structures form on the friction surface as a consequence of a self-organization process, resulting in an overall wear rate reduction. It has been demonstrated that a tribo-system begins to lose its thermodynamic stability once it reaches the point of maximum entropy production during the running-in stage.

ANALYSIS OF THE SINKHOLE FORMATION MECHANISM IN PERMAFROST ROCKS IN THE SITE OF INTRAPERMAFROST GROUNDWATER DEVELOPMENT WITH REGARDS OF DISSIPATIVE GEOLOGICAL STRUCTURES

The paper considers hazardous phenomena on the Earth’s surface such as sinkholes within the Lena River floodplain terrace, the Central Yakutia, in the areas of intrapermafrost groundwater development. Possible mechanisms for the formation of a dip based on thermosuffusion and the mechanism of formation of dissipative geological structures are investigated. The materials of monitoring and geophysical works in the areas of manifestation of failures are analyzed.

Dissipative Solitons and Switching Waves in Dispersion-Modulated Kerr Cavities

We theoretically and experimentally investigate the formation of dissipative coherent structures in Kerr nonlinear optical microresonators, whose spectrum encompasses an integrated dispersion that exceeds the cavity free-spectral range. We are able to access this regime in low-dispersion photonic chip-based microresonators by employing synchronous pulse driving, which increases the peak power over the continuous-wave-driving regime. Exploring this dispersion-folded regime, we demonstrate that the presence of periodically varying dispersion can excite higher-order comb structures, which we explore in both the normal and anomalous dispersion regimes. In the former, we observe the coexistence of switching wave fronts with Faraday instability-induced period-doubling patterns. They manifest as strong satellite microcombs highly separated either side of the core microcomb, at an offset close to half the repetition rate but while sharing the same repetition rate. In the latter, for dissipative Kerr solitons in anomalous dispersion, we observe the formation of higher-order phase-matched dispersive waves (“Kelly-like” sidebands), where the folded dispersion crosses the frequency comb grid. We observe up to the fifth higher-order dispersive wave in our experiments and show that these higher-order dispersive waves coherently extend the soliton frequency comb bandwidth significantly. For both cases, we show that our results can be understood by considering four-wave mixing in a two-dimensional Fourier transform representation. The results demonstrate the rich novel nonlinear dynamics of driven dissipative nonlinear cavities with periodically varying dispersion in the dispersion-folded pumping regime.2 MoreReceived 19 June 2022Accepted 14 February 2023DOI:https://doi.org/10.1103/PhysRevX.13.011040Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasPattern formationSpatiotemporal chaosPhysical SystemsCoherent structuresFloquet systemsFront propagationNonlinear wavesSolitonsSynchronizationNonlinear Dynamics

Dynamic Processes of Self-Organization in Nonstationary Conditions of Friction

Self-organization mechanisms of metastable dissipative structures during friction depending on base and oil functional additives for hypoid gears are considered. Research was conducted on a software-hardware complex with simulation of gears’ operation in rolling with slipping conditions in start-stop mode. Indicators of formation of wear-resistant dissipative structures include the following: improvement of antifriction characteristics, lubricant boundary layers’ formation, contact surfaces’ strengthening, and formation of heterogeneous deformation microrelief with a fine-grained structure. The formation of chemically modified boundary layers on 90% of the contact area of tribo-coupling elements ensures an increase in the wear resistance of leading and lagging surfaces by 2 and 1.4 times, respectively. The sclerometry method was used to establish that the formation of dissipative structures when lubricating tribo-coupling elements with various transmission oils can reduce deformation processes in metal near-surface layers by 23%. Highly viscous flavored lubricant with distillate oil and additive composition ensures wear-resistant dissipative structures with active components, including oxygen, sulfur, and phosphorus.

ГЕОЛОГИЧЕСКИЕ ОСНОВЫ РАСЧЕТА ОСАДОК ГРУНТОВЫХ ОСНОВАНИЙ

The article discusses the geological regularities of the transformation of the stress-strain state of the soil foundation through the formation of dissipative geological structures that interact between the geological environment and the foundation. The technology of calculation of the ground base settlement is presented. A specific example of estimation of strip foundation settlement shows that the proposed technology is efficient and can be further used for practical purposes

Formation of dissipative structures in microscopic models of mixtures with species interconversion

The separation of substances into different phases is ubiquitous in nature and important scientifically and technologically. This phenomenon may become drastically different if the species involved, whether molecules or supramolecular assemblies, interconvert. In the presence of an external force large enough to overcome energetic differences between the interconvertible species (forced interconversion), the two alternative species will be present in equal amounts, and the striking phenomenon of steady-state, restricted phase separation into mesoscales is observed. Such microphase separation is one of the simplest examples of dissipative structures in condensed matter. In this work, we investigate the formation of such mesoscale steady-state structures through Monte Carlo and molecular dynamics simulations of three physically distinct microscopic models of binary mixtures that exhibit both equilibrium (natural) interconversion and a nonequilibrium source of forced interconversion. We show that this source can be introduced through an internal imbalance of intermolecular forces or an external flux of energy that promotes molecular interconversion, possible manifestations of which could include the internal nonequilibrium environment of living cells or a flux of photons. The main trends and observations from the simulations are well captured by a nonequilibrium thermodynamic theory of phase transitions affected by interconversion. We show how a nonequilibrium bicontinuous microemulsion or a spatially modulated state may be generated depending on the interplay between diffusion, natural interconversion, and forced interconversion.

An empirical analysis of social public resources digital sharing system: Dissipative structure theory.

The development of the social public resource digital sharing system (SPRDSS) has been accelerated with the evolution of digital information and communication technologies (ICTs). This paper analyzes the dissipative structure features and formation process of SPRDSS in China. Combined with the Brusselator model and its transformation, this paper empirically analyzes the dissipative structure of SPRDSS using panel data collected from 30 Chinese provinces (excluding Tibet, Hong Kong, Macao, and Taiwan) from 2015 to 2019. The results show that the SPRDSS in China has pre-conditions to form a dissipative structure. At present, the SPRDSSs in most Chinese provinces have not yet formed the dissipative structure, but they are gradually evolving into it. The global orderliness of the sharing system is greater in eastern China than in central China and greater in central China than in western China. The potential for improving global orderliness is greater in western China than in central China and is greater in central China than in eastern China. Therefore, proper policies and measures should be adopted to accelerate the construction of SPRDSS based on the evolution of dissipative structure and to promote the sustainable development of the digital sharing economy.

Formation of dissipative structures in a three-dimensional electro-thermo-convective flow

Three-dimensional electro-thermo-convective flow between two parallel plates under a simultaneously applied voltage and temperature difference is studied with linear stability analysis, direct numerical simulations, and computation of local entropy generation. An infinitesimal random perturbation is found to grow into a rolls pattern, then partially break up into polygons, and finally evolve into hexagons. The rolls pattern always has a larger total entropy generation and mean-square temperature gradient than the hexagon pattern, indicating that the rolls pattern is relatively more stable under these conditions.

Physico-chemical properties of perturbed water: facts and enigmas

Physico-chemical properties of perturbed water: facts and enigmas

Функциональные возможности электромагнитно-акустических преобразований в токовом режиме в металлическом расплаве

The paper deals with a symmetric problem on the base of physically substantiated estimates of the processes of electromagnetic-acoustic transformations (EMAT) of energy during the flow of an electric current through a melt, the key parameters of the open problem of the system "Power source parameters – Parameters of the magnetic field and magnetic pressure of the skin layer – Parameters of acoustic disturbances". It was shown that the key parameter when formulating the EMAT problem in technological applications is the geometry of the container with the object of processing and the material of the form. And when solving the problem, they are the parameter of the skin layer and the time dependence of the discharge current. It was established that a part of energy during the formation of the magnetic pressure in the skin layer from the amount of the energy stored in the capacitor bank of the pulse current generator is on the order of 10-4–10-2. The value of this part depends on the period of the discharge current and is proportional to the T1/2. When acoustic disturbances propagate in a melt, the main share of energy losses is determined by the difference in the acoustic stiffness of the melt and the shape of materials. The frequency spectra of the pressure of sound waves at the parameters selected for the analysis can cover the range of up to hundreds kHz, which is a good reason for the realization of resonance effects and the active formation of dissipative structures. Attention is focused on the fact that EMAT effects are manifested in the melt not only under the influence of an acoustic field, but also under that of an electromagnetic one in the skin layer. They are separated in time, but the acoustic field can occupy the entire volume of the melt and its effect is longer in time.

Absolute Asymmetric Catalysis, from Concept to Experiment: A Narrative

AbstractThe generally accepted hypothesis to explain the origin of biological homochirality (that is to say, the fact that proteinogenic amino acids are left-handed, and carbohydrates right-handed, in all living beings) is to assume, in the course of prebiotic chemical evolution, the appearance of an initial enantiomeric excess in a set of chiral molecular entities by spontaneous mirror-symmetry breaking (SMSB), together with suitable amplification and replication mechanisms that overcome the thermodynamic drive to racemization. However, the achievement of SMSB in chemical reactions taking place in solution requires highly specific reaction networks showing nonlinear dynamics based on enantioselective autocatalysis, and examples of its experimental realization are very rare. On the other hand, emergence of net supramolecular chirality by SMSB in the self-assembly of achiral molecules has been seen to occur in several instances, and the chirality sign of the resulting supramolecular system can be controlled by the action of macroscopic chiral forces. These considerations led us to propose a new mechanism for the generation of net chirality in molecular systems, in which the SMSB takes place in the formation of chiral supramolecular dissipative structures from achiral monomers, leading to asymmetric imbalances in their composition that are subsequently transferred to a standard enantioselective catalytic reaction, dodging in this way the highly limiting requirement of finding suitable reactions in solution that show enantio­selective autocatalysis. We propose the name ‘absolute asymmetric catalysis’ for this approach, in which an achiral monomer is converted into a nonracemic chiral aggregate that is generated with SMSB and that is catalytically active.Our aim in this Account is to present a step-by-step narrative of the conceptual and experimental development of this hitherto unregarded, but prebiotically plausible, mechanism for the emergence of net chirality in molecular reactions.1 Introduction: The Origin of Biological Homochirality and Spontaneous Mirror-Symmetry Breaking2 Experimental Chemical Models for Spontaneous Mirror-Symmetry Breaking: The Soai Reaction and Beyond3 Spontaneous Mirror-Symmetry Breaking in Supramolecular Chemistry: Plenty of Room at the Top4 Absolute Asymmetric Catalysis: An Alternative Mechanism for the Emergence of Net Chirality in Molecular Systems 5 Experimental Realization of Top-Down Chirality Transfer to the Molecular Level6 Conclusions and Outlook

The Formation of the Electronic Tornado is the Basis of Superconductivity

The space-time ladder theory reveals that the formation of electronic tornadoes, or the formation of electronic dissipative structures, to be precise, the enhancement of electronic Energy Qi field is the basis of superconductivity. The surrounding area of the electronic tornado is expanding, which is the basis of the Meissner effect, and the center is contracting, which is the basis of the pinning force. When the attractive force of the Energy Qi field is greater than the Coulomb repulsive force, the electrons form a Cooper pair and release dark energy into virtual space-time. When the dark energy increases to a certain extent, the virtual space-time frees the Cooper pair and forms an electron-virtual space-time wave, which fluctuates freely in the superconducting material, which is the basis for the superconducting resistance to be zero. This is similar to the principle of a hot air balloon. The virtual space-time is hot air and the electron pair is a hot air balloon device. Conductor electrons are free and easy to emit dark energy, resulting in insufficient dark energy, and it is not easy to form electron-pair virtual space-time waves, so the superconducting critical temperature is very low. This is because the emission coefficient of the conductor is too high. Insulator electrons are not easy to emit dark energy and easily form electron-pair virtual space-time waves. Therefore, the superconducting critical temperature is slightly higher because of the low emission coefficient of the insulator. The solution of the Qi-space-time wave equation, that is, the coherence coefficient, is an important factor in superconductivity. In addition, the conditions under which tornadoes form are also an important basis for superconductivity. Finally, it is emphasized that the coherence coefficient and prevention of dark energy emission are the two most important elements for preparing superconducting materials.

Formation of Dissipative Structures in the Straight Segment of Electrospinning Jets

Accurate jet diameters have been experimentally obtained during electrospinning by the light-scattering technique together with the Mie theory for cylinder scattering. Afterward, the fluid velocity...

Formation of Dissipative Structure of Metastable Austenite for Raising the Abrasive Wear Resistance of Steels of Pearlitic and Ledeburitic Classes

The structure of retained austenite in wear-resistant steels 150KhNML and Kh12MFL of pearlitic and ledeburitic classes is studied under the conditions of abrasive wear after different variants of heat treatment. The working surfaces of the steels are subjected to electron microscope transmission analysis. It is shown that the retained austenite formed as a result of high-temperature quenching (1100 – 1170°C) is metastable and transforms in the wear process into fine- and nanocrystalline strain martensite with regular periodic arrangement of crystals in addition to slip and twinning. This provides a high capacity of the working surface for friction hardening. The optimum mode of heat treatment for formation of a dissipative structure with high abrasive wear resistance is chosen.

Dehydrogenation of a mixture of light alkanes on supported platinum metals in a reducing atmosphere

A mixture of light alkanes simulates associated gas of oil production, the growth of oil and gas production in the world, and especially in Kazakhstan, leads to the fact that associated gases of oil production continue to be flared, causing significant harm to the environment, at a time when they are a valuable petrochemical feedstock. Active and selective catalysts are needed to convert inert alkanes to olefins. We prepared 3% Pt, Pd, Ru on γ – Al2O3 by the incipient wetness impregnation method. The transformation of a mixture of light alkanes C1-C4 has been carried out on a laboratory flow-bench apparatus in four modes at atmospheric pressure and temperatures of 350-500oC. The freshly prepared and spent catalysts were investigated by physicochemical methods TEM, SEM and BET. The maximum yield is formed for 3% Ru / γ – Al2O3 when a mixture of light alkanes with water is fed together at 500 ° C. We assume that water shifts the equilibrium in the system, resulting in the formation of dissipative structures that affect the activity of catalysts.

Variation of Relief Topography and Hardness of Surface Layers of Materials Due to Impact-Oscillatory Loading

It was shown previously that cyclic loading can be used to extend the fatigue life of sheet plastic materials subjected to the preliminary impact-oscillatory loading. This type of loading causes dynamic non-equilibrium processes (DNP) in materials, which lead to the formation of dissipative structures in materials and on their surface. The density of these dissipative structures is less than that of the base metal. In this paper, the results of investigations into the relief and hardness of surface layers modified by impact-oscillatory loading are analyzed on the example of five structural materials. The signs of a regular, orderly system of microextrusions formed on flat surfaces of all materials due to DNP are considered along with the alignment of roughness parameters Rz and Ra of relief profiles. The effect of impact-oscillatory loading is one of the main causes that lead to the extension of the fatigue life of materials.

Dissipative effect in liquid under exposure to low-frequency sound vibrations

The article describes the formation of dissipative structures in a liquid in a metal bowl when exposed to lowfrequency sound vibrations. The fluctuating volumes in a thick layer of liquid, that is, clusters of molecules, which make an oscillatory motion and with a loss of stability occupying a new position in the liquid, are investigated. An external synchronous effect on a group of molecules can lead to increasing oscillations and loss of stability not only inside the liquid, but these groups of molecules can leave the liquid through the free surface.Friction on the outer surface of a bowl made of a conductive bronze-containing alloy, which initiates the occurrence of sound vibrations, gives rise to the appearance of new structures in the fluid inside the bowl. The thickness of the liquid layer is about 50 mm. The coordinated addition of energy to the oscillating microvolumes of water allows them to release their potential energy and turn it into kinetic. Water droplets ejected vertically indicate the existence of intense vertical movement of individual volumes of fluid which create new structures and cells, like Benard cells, resulting from heating and vertical convection, but smaller sizes. The observed phenomenon is similar to “cold boiling”. Here, probably, the potential energy of the compressed water particles is released under the influence of external sound vibrations. Sound analysis was performed using an audio editor for several experiments of various lengths.In this work, the dissipative effect in a thick layer of liquid when exposed to low-frequency sound vibrations and the appearance of structures identical to Benard cells in limited volumes of water (and not in a thin layer) is first investigated. It should be assumed that the effect of sound vibrations can lead to blood turbulization and a change in the physical state of living organisms, which in terms of physical effect can be similar to the state of blood boiling with a rapid rise from the depth of the sea. The phenomenon can be used for the intensification of heat and mass transfer in heat exchange installations.