Field Structure Research Articles

Dynamic characterization of the flow field of air classifier disturbed structures and application to efficient separation of fly ash

Classification is crucial for the resource utilization of fly ash, impacting both utilization rates and product quality. This study introduces an enhanced flow field structure in a perturbed rotating centrifugal air classifier by optimizing toothed and tail blade designs for efficient fly ash classification. Using numerical simulations and experiments, we examine the flow field performance and separation efficacy at various speeds, and employ Dynamic Mode Decomposition (DMD) for modal analysis. Results show the toothed blade, angled at 35°, produces small-scale turbulence with high pressure and velocity, while the tail blade’s rightward bend induces large-scale vortices, aiding flow control. Modal analysis highlights that both Drs-types 1 and 2 predominantly exhibit weakly attenuated modes. Optimal classification occurs at Rs = 950rpm and fv = 0.3kg/s, with both Drs-types surpassing the original structure in effectiveness and pressure. These findings provide new directions for industrial applications and the design of cyclone air classifiers.

Numerical study on dynamic response characteristics of proton exchange membrane water electrolyzer under transient loading

Under dynamic operating conditions, the proton exchange membrane water electrolyzers are prone to voltage overshoot, resulting in fluctuations under transient operation. In this paper, a three-dimensional, two-phase, non-isothermal model is developed to investigate the role of various factors on the dynamic response characteristics of electrolyzers. The results demonstrate that the overshoot phenomenon can be significantly mitigated by using a linear loading strategy and a multi-step loading strategy compared to a step loading strategy. Meanwhile, the effect of the flow field structure was examined, revealing that single-serpentine flow field exhibited excellent dynamic response performance. Additionally, calculated through multiple evaluation methods, it was found that the effect of loading magnitude was significantly greater than that of the other factors, including temperature, flow field structure and anode porous transport layer porosity. Finally, under combined variable load conditions, research revealed that whereas single-serpentine flow field shown benefits regarding dynamic response and energy dissipation.

Perspectives on Northern Gulf of Alaska salinity field structure, freshwater pathways, and controlling mechanisms

The biologically productive Northern Gulf of Alaska (NGA) continental shelf receives large inputs of freshwater from surrounding glaciated and non-glaciated watersheds, and a better characterization of the regional salinity spatiotemporal variability is important for understanding its fate and ecological roles. We here assess synoptic to seasonal distributions of freshwater pathways of the Copper River discharge plume and the greater NGA continental shelf and slope using observations from ship-based and towed undulating conductivity-temperature-depth (CTD) instruments, satellite imagery, and satellite-tracked drifters. On the NGA continental shelf and slope we find low salinities not only nearshore but also 100-150 km from the coast (i.e. average 0–50 m salinities less than 31.9, 31.3, and 30.8 in spring, summer, and fall respectively) indicating recurring mid-shelf and shelf-break freshwater pathways. Close to the Copper River, the shelf bathymetry decouples the spreading river plume from the direct effects of seafloor-induced steering and mixing, allowing iron- and silicic acid-rich river outflow to propagate offshore within a surface-trapped plume. Self-organized mapping analysis applied to true color satellite imagery reveals common patterns of the turbid river plume. We show that the Copper River plume is sensitive to local wind forcing and exerts control over water column stratification up to ∼100 km from the river mouth. Upwelling-favorable wind stress modifies plume entrainment and density anomalies and plume width. Baroclinic transport of surface waters west of the river mouth closely follow the influence of alongshore wind stress, while baroclinic transport east of the river mouth is additionally modified by a recurring or persistent gyre. Our results provide context for considering the oceanic fate of terrestrial discharges in the Gulf of Alaska.

Spatial structure of light fields at Gaussian beams transmission through multilayer dielectrics under the total internal reflection and waveguide excitation

Spatial structure of light fields at Gaussian beams transmission through multilayer dielectrics under the total internal reflection and waveguide excitation

Cosmological implications of the minimum viscosity principle

It is shown that black holes in a quark gluon plasma (QGP) obeying minimum viscosity bounds exhibit a Schwarzschild radius in close match with the range of interaction of the strong force. For such black holes, an evaporation time of about [Formula: see text] s is estimated, indicating that they would survive by far the quark-gluon plasma era, namely between [Formula: see text] and [Formula: see text] s after the big bang. On the assumption that the big-bang generated unequal amounts of quark and antiquarks, this suggests that such unbalance might have survived to this day in the form of excess antiquark nuggets hidden to all but gravitational interactions. A connection with the saturon picture, whereby minimum viscosity regimes would associate with the onset coherent quantum field structures with maximum storage properties, is also established.

Interacting Kerr-Newman electromagnetic fields

In this paper, we study some of the properties of the G→0 limit of the Kerr-Newman solution of Einstein-Maxwell equations. Carter noted the near equality between the gyromagnetic ratio, or g-factor, of the Kerr-Newman solution and of the electron. This observation is a consequence of the multipole structure of the Kerr-Newman field. We discuss additional coincidences between the Kerr-Newman multipole structure and the properties of the electron. In contrast to the Coulomb field, this spinning Maxwell field has a finite Lagrangian. Moreover, by evaluating the Lagrangian for the superposition of two such Kerr-Newman electromagnetic fields on a flat background, we are able to find their interaction potential. This yields a correction to the Coulomb interaction due to the spin of the field. Published by the American Physical Society 2024

Wind tunnel experimental study on the influence of super-large natural ventilation cooling tower on the flow and diffusion of pollutants

ABSTRACT In this paper, a wind tunnel experiment was carried out to study the atmospheric flow and pollutant diffusion around a super-large natural ventilation cooling tower of a nuclear power plant. Considering the effect of the natural ventilation of the cooling tower, with the chimney as the center, X-type hot-wire probes were used to measure the average flow field and turbulence structure of the atmosphere around the cooling tower and other complexes, and pollutant diffusion studies were carried out by tracer experiments. The results show that the super-large natural ventilation cooling tower and its thermal plume emission have a significant effect on pollutant flow and diffusion, changing the trajectory of the plume. When the chimney is located upwind of the cooling tower, some pollutants are emitted secondly due to the entrainment effect through the cooling tower when the plume passes through the natural ventilation cooling tower, regardless of whether or not the cooling tower is operating. Compared with the cooling tower that does not operate, the thermal plume and natural ventilation effects generated by the cooling tower during operation cause the plume dispersion range to widen, the maximum concentration to decrease, and the impact on vertical diffusion to be more significant than that on horizontal diffusion.

Investigating the Dynamics of a Unidirectional Wave Model: Soliton Solutions, Bifurcation, and Chaos Analysis

The current work investigates a recently introduced unidirectional wave model, applicable in science and engineering to understand complex systems and phenomena. This investigation has two primary aims. First, it employs a novel modified Sardar sub-equation method, not yet explored in the literature, to derive new solutions for the governing model. Second, it analyzes the complex dynamical structure of the governing model using bifurcation, chaos, and sensitivity analyses. To provide a more accurate depiction of the underlying dynamics, they use quantum mechanics to explain the intricate behavior of the system. To illustrate the physical behavior of the obtained solutions, 2D and 3D plots, along with a phase plane analysis, are presented using appropriate parameter values. These results validate the effectiveness of the employed method, providing thorough and consistent solutions with significant computational efficiency. The investigated soliton solutions will be valuable in understanding complex physical structures in various scientific fields, including ferromagnetic dynamics, nonlinear optics, soliton wave theory, and fiber optics. This approach proves highly effective in handling the complexities inherent in engineering and mathematical problems, especially those involving fractional-order systems.

Magnetic interaction of stellar coronal mass ejections with close-in exoplanets: implication on planetary mass loss and Ly-α transits

Abstract Coronal Mass Ejections (CMEs) erupting from the host star are expected to affect the atmospheric erosion processes of planets. For planets with a magnetosphere, the embedded magnetic field in the CMEs is thought to be the most important parameter to affect planetary mass loss. In this work, we investigate the effect of different magnetic field structures of stellar CMEs on the atmosphere of a hot Jupiter with a dipolar magnetosphere. We use a time-dependent 3D radiative magnetohydrodynamics (MHD) atmospheric escape model that self-consistently models the outflow from hot Jupiter’s magnetosphere and its interaction with stellar CMEs. For our study, we consider three configurations of magnetic field embedded in CMEs - (a) northward Bz component, (b) southward Bz component, and (c) radial component. We find that both the CMEs with northward Bz and southward Bz increase the planetary mass-loss rate when the CME arrives from the stellar side, with the mass-loss rate remaining higher for the CME with northward Bz until it arrives on the opposite side. The largest magnetopause is found for the CME with a southward Bz component. During the passage of a CME, the planetary magnetosphere goes through three distinct changes - (1) compressed magnetosphere, (2) enlarged magnetosphere and (3) relaxed magnetosphere for all three CME configurations. The computed synthetic Ly-α transit absorption generally increases when the CME is in interaction with the planet for all magnetic configurations but the maximum Ly-α absorption is found for the case of radial CME with the most compressed magnetosphere.

Hyperon Production in Bi + Bi Collisions at the Nuclotron-Based Ion Collider Facility and Angular Dependence of Hyperon Spin Polarization

The strange baryon production in Bi + Bi collisions at sNN=9.0 GeV is studied using the PHSD transport model. Hyperon and anti-hyperon yields, transverse momentum spectra, and rapidity spectra are calculated, and their centrality dependence and the effect of rapidity and transverse momentum cuts are studied. The rapidity distributions for Λ¯, Ξ, Ξ¯ baryons are found to be systematically narrower than for Λs. The pT slope parameters for anti-hyperons vary more with centrality than those for hyperons. Restricting the accepted rapidity range to |y|<1 increases the slope parameters by 13–30 MeV, depending on the centrality class and the hyperon mass. Hydrodynamic velocity and vorticity fields are calculated, and the formation of two oppositely rotating vortex rings moving in opposite directions along the collision axis is found. The hyperon spin polarization induced by the medium vorticity within the thermodynamic approach is calculated, and the dependence of the polarization on the transverse momentum and rapidity cuts and on the centrality selection is analyzed. The cuts have stronger effect on the polarization of Λ and Ξ hyperons than on the corresponding anti-hyperons. The polarization signal is maximal for the centrality class, 60–70%. We show that, for the considered hyperon polarization mechanism, the structure of the vorticity field makes an imprint on the polarization signal as a function of the azimuthal angle in the transverse momentum plane, ϕH, cosϕH=px/pT. For particles with positive longitudinal momentum, pz>0, the polarization increases with cosϕH, while for particles with pz<0 it decreases.

Evaluating the Conceptual Development of Healthcare Leadership Literature with a Network Approach

Analysis of co-word networks can be used in discovering themes that reflect both the cognitive structure of the scientific field and the gap in the field, besides following the conceptual change in the scientific field. This study aims to reveal the development of the "healthcare leadership" literature, which started to attract more attention with the COVID-19 Pandemic. The authors searched for all articles written in English between 2020 and 2023 in Web of Science Core Collection and Scopus databases with the key phrases “healthcare leadership”, “healthcare leader”, “health care leadership” or “health care leader” as the query to search the following fields within a record: Title, Abstract, and Author Keywords. 134 articles in the Web of Science database and 585 articles in the Scopus database were reached. Duplicate articles (271) were first eliminated, then articles with one keyword (12) were excluded since one keyword is not appropriate for network analysis. Consequently, 1,360 unique keywords of 2,372 keywords from 436 articles were entered into the analysis scope. A network of whole years was constructed based on word frequency co-occurrence matrices with keywords from all years included, besides a network for each year. Descriptive statistics such as network density, connected components, and total number of ties were calculated for the whole network. Centrality measures were calculated for the network of whole years and each year. Network density and number of the connected components were found as 0.012 and 27 respectively. Leadership, COVID-19/Pandemic, healthcare, healthcare leadership, qualitative research, and nurse were the first six concepts with the highest degree centrality, betweenness centrality, and eigenvector centrality for the network of whole years. Thus, it was possible to see both the general view of the cognitive structure of the healthcare leadership literature and conceptual change in the literature over the years. The findings have the potential to provide important clues for trends and future research directions in this field.

Turbulent plasma flow, its energies, and structures: Velocity vortices, magnetic field cocoons, and plasmoids

Turbulent flows are believed to be present in the solar corona, especially in connection with solar flares and coronal mass ejections. They are supposed to be very effective processes in energy transportation and can contribute to the heating of the solar corona. We study turbulence in reconnection outflows associated with flares and coronal mass ejections. We simulated the generation and evolution of the turbulent plasma flow and investigated its energies and formed plasma velocity and magnetic field structures. For the numerical simulations, we adopted a three-dimensional (3D) magnetohydrodynamic (MHD) model, in which we solved a full set of the 3D time-dependent resistive and compressible MHD equations using the Lare3d numerical code. We numerically studied turbulence in the plasma flow in the model with the plasma parameters that could simulate processes in the magnetic reconnection outflows in solar flares. Starting from a non-turbulent plasma flow in the energetically closed system, we studied the evolution of the kinetic, internal, and magnetic energies during the turbulence generation. We found that most of the kinetic energy is transformed into the plasma heating (about $95 <!PCT!>$) and only a small part to the magnetic energy (about $5 <!PCT!>$). The turbulence in the system evolves to the saturation stage with the power-law index of the kinetic density spectrum, $-5/3$. Magnetic energy is also saturated due to its dissipation and reconnection in small and complex magnetic field structures. We show examples of the structures formed in studied turbulent flow: velocity vortices, magnetic field cocoons, and plasmoids.

Bidirectional propagating brightenings in arch filament systems observed by Solar Orbiter/EUI

Arch filament systems (AFSs) are chromospheric and coronal manifestations of emerging magnetic flux. Using high spatial resolution observations taken at a high cadence by the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter, we identified small-scale elongated brightenings within the AFSs. These brightenings appear as bidirectional flows along the threads of AFSs. For our study, we investigated the coordinated observations of the AFSs acquired by the EUI instrument and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) on 2022 March 4 and 17. We analyzed 15 bidirectional propagating brightenings from EUI 174 AA images. These brightenings reached propagating speeds of 100--150 km s$^ $. The event observed on March 17 exhibits blob-like structures, which may be signatures of plasmoids and due to magnetic reconnection. In this case, we also observed counterparts in the running difference slit-jaw images in the 1400 AA passbands taken by the Interface Region Imaging Spectrograph (IRIS). Most events show co-temporal intensity variations in all AIA EUV passbands. Together, this implies that these brightenings in the AFSs are dominated by emission from cool plasma with temperatures well below 1 MK. The Polarimetric and Helioseismic Imager (PHI) on board Solar Orbiter provides photospheric magnetograms at a similar spatial resolution as EUI and from the same viewing angle. The magnetograms taken by PHI show signatures of flux emergence beneath the brightenings. This suggests that the events in the AFSs are triggered by magnetic reconnection that may occur between the newly emerging magnetic flux and the preexisting magnetic field structures in the middle of the AFSs. This would also give a natural explanation for the bidirectional propagation of the brightenings near the apex of the AFSs. The interaction of the preexisting field and the emerging flux may be important for mass and energy transfer within the AFSs.

The thrust balance model during the dragonfly hovering flight

In recent years, the micro air vehicle (MAV) oscillations caused by thrust imbalances have received more attention. This paper proposes a dual-wing thrust balance model (DTBM) that can solve the above problem by iterating the modified rotation angle formula. The core control parameter of the DTBM model is the au angle, which refers to the angle between the wing surface and the stroke plane at the mid-stroke position during the upstroke. For each degree change in the au angle, the range of variation in the dimensionless average thrust coefficient is between 0.0225-0.0268. A thrust coefficient of 0.0225 causes the dragonfly to move forward by 9.037 cm in one second, which is equivalent to 1.29 times its body length. By using DTBM, the average thrust coefficient can be reduced to below 0.001 in just a few iterations. No matter how complex the motion pattern is, the DTBM can achieve thrust balance within 0.278 s. Through our research, when selecting the deviation angle motion of real dragonflies, the dual-wing au angles exhibit a highly linear correlation with wing spacing, called linear motion. In contrast, the nonlinear variation of the au angle appears in the hindwing of the no-deviation motion and the forewing of the elliptical deviation motion. All of the nonlinear changes are referred to as nonlinear motion. Nonlinear variation of the au angle arises from larger disturbances of the lateral force during the upstroke. The stronger lateral force is closely related to the flapping trajectory. When the flapping trajectory causes the dual-wing to closely approach each other in the mid-stroke, a continuous positive pressure zone forms between the dual-wing. The collision of the leading-edge vortex and the shedding of the trailing-edge vortex is the special flow field structure in the nonlinear motion. Guided by the DTBM, future designs of MAVs will be able to better achieve thrust balance during hovering flight, requiring only the embedding of the iteration algorithm and prediction function of the DTBM in the internal chip.

Interplay between Dynamic Phase and Geometric Phase Determines the Circular Dichroism and Helical Dichroism.

Understanding the interaction between light and chiral nanostructures is of fundamental importance, yet the principles governing chiral interactions have remained largely phenomenological. In this work, we present a chiral field-mode (FM) matching model to quantify the circular dichroism (CD) and helical dichroism (HD) of chiral plasmonic nanostructures interacting with beams of different spin-orbit states. The chiral FM matching model posits that among the inherent resonance modes within the nanostructure, the most efficiently excited mode is the one that matches the external field structure by possessing one more node along the vibration direction, with the field structure itself being determined by the interaction between the geometric phase and dynamic phase through a Doppler-like effect. The geometric phase in this model is well-defined by the product of the winding angle of the nanohelix and the angular momenta of light, including both its spin and orbital components. Thus, the beams of different spin-orbit states excite the specific resonance mode possessing one more node compared with the field structure, resulting in the spin-related CD and orbit-related HD. This model is extended to various chiral nanocomplexes, demonstrating how the field structure determines mode excitation and offering a comprehensive explanation for the CD and HD observed in various experimental setups. This model offers insights into the CD and HD microscopy in chiral nanostructures, contributing to the advancement of the fundamental theory of chiral nanophotonics.

Discovery of the preferred direction of electric vector position angle rotations in blazars

Blazars are a subclass of active galactic nuclei (AGNs) with a high optical linear polarization that originates in relativistic jets. Polarization parameters such as the degree of polarization (PD) and the electric vector position angle (EVPA) are directly related to the properties of the magnetic field in the jets. A study of the optical polarization of blazars allows conclusions to be drawn about the field geometry, its evolution, and its relation to the emission properties of the blazars. The periods of ordered changes in the electric vector position angle, so-called rotations, are of particular interest. We used a new method to determine EVPA rotations and to estimate their statistical significance with the aim to analyze long-term polarimetric observations of five blazars: OJ 287, S5 0716+71, 3C 454.3, CTA 102, and PG 1553+113. This resultes in the identification of 256 EVPA rotations. We found possible tendencies for the EVPA rotations to occur in a preferred direction in each of these sources: clockwise for OJ 287 and CTA 102, and counterclockwise for the others. The EVPA rotations can be explained by the spiral structure of the magnetic field in the jet. In this case, the observed preferred direction of rotations reflects the global structure of the magnetic field, which can be associated with the direction of rotation of either the black hole ergosphere or the accretion disk.

Seismic structure of the Wudalianchi volcanic field in Northeast China: insights into magma reservoir and crustal magmatic plumbing systems

Seismic structure of the Wudalianchi volcanic field in Northeast China: insights into magma reservoir and crustal magmatic plumbing systems

RESEARCH ON THE ISSUES OF DIGITAL TRANSFORMATION: BIBLIOMETRIC ANALYSIS

Due to the capabilities offered by automation of management processes, the scope of application for information systems and technologies (IST) as a research subject is expanding exponentially, covering a wide range of related topics, fields of knowledge, and areas of activity. This expansion highlights the importance of studying the conceptual framework and trends in digital transformation. The purpose of this article is to examine the quantitative and qualitative structure of scientific publications on digitalization, key research directions, and to identify prospects for further developments in digital transformation. The article presents results of a bibliometric analysis of scientific publications on digitalization issues indexed in the SCOPUS scientometric database. The embedded analytical tools in SCOPUS were used to analyze the selected publications sample. Bibliometric indicators included: annual publication dynamics and the structure of scientific fields associated with these publications. An important part of the study is an analysis of the content of the most-cited publications in the sample. Keyword analysis revealed that the most commonly used keywords by authors are "digitalization," "transformation," and "innovation." It was found that digital transformation in scholarly work generally focuses on two areas: (1) digitalization as a product and outcome of IST application, aimed at meeting the needs of various stakeholders, and (2) digitalization as the process of IST creation. This result confirms the close link between digital transformation and innovative activities, highlighting two types of innovations: product-innovation and process-innovation. It was found that the relevance and continuous development of IST research are influenced by highly cited publications from researchers primarily affiliated with universities in developed countries. Bibliometric analysis of publications related to digital transformation has demonstrated a growing interest among researchers in this topic. Over the past decade, there has been a steady increase in the number of scientific articles dedicated to this issue, and the context in which the topic of digitalization is considered has proven to be quite diverse. Researchers from various countries are studying the impact of digitalization on the economy and social processes as a whole. Conclusions are drawn regarding the identified trends, and the potential for future research topics is summarized.

The Phase Structure of Wave Disturbances Excited by a Pulsating Source at the Interface of a Liquid Flow of Finite Depth and an Ice Sheet

The floating ice sheet determines the dynamic interaction between the ocean and the atmosphere, affects the dynamics of the sea surface and subsurface waters, since the ice sheet and the entire mass of liquid under it participate in the general vertical movement. The paper investigates the phase structure of wave fields arising at the interface between ice and a flow of homogeneous liquid of finite thickness when flowing around a localized pulsating source of disturbances. The ice sheet is modeled by a thin elastic plate, the deformations of which are small, and the plate is physically linear. An integral representation of the solution is obtained, and the results of calculations of dispersion dependencies and phase patterns for various parameters of wave generation are presented. It is shown that the main parameters determining the characteristics of the amplitude-phase structure of wave disturbances of the ice sheet surface are ice thickness, flow velocity, and pulsation frequency. Numerical calculations demonstrate that when the flow velocities, ice thickness, and frequency change, there is a noticeable qualitative restructuring of the phase patterns of the excited long-range wave fields at the ice-liquid interface.

Depolarization and Faraday effects in AGN Jets

ABSTRACT Radio interferometric observations of active galactic nuclei (AGN) jets reveal the significant linear polarization of their synchrotron radiation that changes with frequency due to the Faraday rotation. It is generally assumed that such depolarization could be a powerful tool for studying the magnetized plasma in the vicinity of the jet. However, depolarization could also occur within the jet if the emitting and rotating plasma are cospatial (i.e. the internal Faraday rotation). Burn obtained very simple dependence of the polarization on the wavelength squared for the discrete source and resolved slab that is widely used for interpreting the depolarization of AGN jets. However, it ignores the influence of the non-uniform large-scale magnetic field of the jet on the depolarization. Under the simple assumptions about the possible jet magnetic field structures, we obtain the corresponding generalizations of Burn’s relation widely used for galaxies analysis. We show that the frequency dependences of the Faraday rotation measure and polarization angle in some cases allow to estimate the structures of the jets magnetic fields.