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"Particle dynamics"
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Influence of Liquid on Particle Dynamics in a Rotary Fluidized Bed
In this work, the particle dynamics within a rotary granulator will be investigated using a novel measurement technique that allows the tracking of magnetic tracer particles. In particular, the influence of liquid on the dynamics will be investigated, since rotary granulators are often used for the production of agglomerates or for spheronization, where a binder liquid is used in these processes. The particle dynamics are defined by means of 2D cross-sectional diagrams and distributions of the particle velocities. In addition, models for the evaluation of the particle dynamics are applied and compared. Apart from the influence of the liquid, whereby the influence of the volume ratio and the viscosity is examined, operating parameters of the rotary granulator are varied as well.
eBook
Dust Complex for Studying the Dust Particle Dynamics in the Near-Surface Atmosphere of Mars
The Dust Complex (DC) instrument was designed to be installed on the landing platform of the ExoMars project. The purpose of the experiment is to study the dynamics of dust particles in the near-surface atmosphere of Mars and to evaluate the main characteristics of the near-surface medium that determine their dynamics. The device makes it possible to register dust particles in the near-surface atmosphere of Mars, determine the main parameters and measure some characteristics of the plasma-dust medium related to the dynamics of dust particles near the Martian surface. The article provides a description of the device, its blocks and sensors, the main elements of the measurement program and characteristics of the measured parameters.
Journal Article
Enhancement of Compatibility of SBS Modified Asphalt by CNTs: Interpretation from Dissipative Particle Dynamics Simulations
The compatibility of styrene-butadiene-styrene (SBS) with base asphalt is known to restrict the application of SBS modified asphalt. In this study, carbon nanotubes (CNT) were used to enhance the compatibility between SBS and base asphalt. The effect of CNTs on the compatibility of SBS modified asphalt was investigated by dynamic mechanics analysis (DMA), and the micro-mechanism of CNTs enhancing the compatibility of SBS modified asphalt was studied by using dissipative particle dynamics (DPD) simulation. The results show that CNTs can significantly improve the compatibility between SBS and base asphalt, and the microscopic mechanism is that CNTs can change the distribution morphology of SBS in base asphalt, making the distribution of SBS modified asphalt more uniform, which promotes the development of polymer-rich phase in SBS modified asphalt. This study can provide theoretical guidance for the practical application of SBS modified asphalt.
Journal Article
SARS-CoV-2 Dynamics in the Mucus Layer of the Human Upper Respiratory Tract Based on Host–Cell Dynamics
A thorough understanding of the inhalation dynamics of infectious aerosols indoors and infection dynamics within the host by inhaled viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays an important role in the assessment and control of infection risks indoors. Here, by combining computational fluid–particle dynamics (CFPD) and host–cell dynamics (HCD), SARS-CoV-2 infection dynamics in the mucus layer of the human upper airway were studied. To reproduce the diffusive and convective transport of the virus in the nasal cavity–nasopharynx by mucociliary motion, a three-dimensional (3D)-shell model with a mucus layer was developed. The initial virus concentrations for HCD calculation were estimated based on the deposition distribution of droplets with representative sizes analyzed by CFPD. To develop a new HCD model, the target-cell-limited model was integrated with the convection–diffusion equation. Additionally, the sensitivity of the infection rate β to the infection dynamics was systematically investigated. The results showed that the time series of SARS-CoV-2 concentration in the mucus layer strongly depended on diffusion, convection, and β. Although the SARS-CoV-2 dynamics obtained here have not been verified by corresponding clinical data, they can preliminarily reveal its transmission mode in the upper airway, which will contribute to the prevention and treatment of coronavirus disease 2019.
Journal Article
3D theory of microscopic instabilities driven by space-charge forces
Microscopic, or short-wavelength, instabilities are known for a drastic reduction of the beam quality and strong amplification of the noise in a beam. Space charge and coherent synchrotron radiation are known to be the leading causes of such instabilities. In this paper, we present a rigorous 3D theory of such instabilities driven by the space-charge forces. We define the condition when our theory is applicable to an arbitrary accelerator system with 3D coupling. Finally, we derive a linear integral equation describing such instability and identify conditions when it can be reduced to an ordinary second-order differential equation.
Journal Article
Plasma-cascade instability
In this paper we describe a new microbunching instability occurring in charged particle beams propagating along a straight trajectory. The nature of these exponentially growing plasma oscillations gave the reason for its name: plasma-cascade instability. Such instability can strongly amplify longitudinal microbunching originating from the beam’s shot noise, even to the point of saturation. Resulting random density and energy microstructures can drastically reduce beam quality. Conversely, such instability can drive novel high-power sources of broadband radiation or can be used as a broadband amplifier. We discovered this phenomenon in a search for such amplifier in the coherent electron cooling scheme without separation of electron and hadron beams. In this paper we present a brief analytical theory of this new phenomenon, detailed numerical studies, the results of experimental demonstration as well as control of the longitudinal plasma-cascade instability.
Journal Article
Plasma-cascade instability
In this paper we describe a new microbunching instability occurring in charged particle beams propagating along a straight trajectory. The nature of these exponentially growing plasma oscillations gave the reason for its name: plasma-cascade instability. Such instability can strongly amplify longitudinal microbunching originating from the beam’s shot noise, even to the point of saturation. Resulting random density and energy microstructures can drastically reduce beam quality. Conversely, such instability can drive novel high-power sources of broadband radiation or can be used as a broadband amplifier. We discovered this phenomenon in a search for such amplifier in the coherent electron cooling scheme [Phys. Rev. Lett. 102, 114801 (2009)] without separation of electron and hadron beams. In this paper we present a brief analytical theory of this new phenomenon, detailed numerical studies, the results of experimental demonstration as well as control of the longitudinal plasma-cascade instability.
Journal Article
Rapidly converging chaos indicator for studying dynamic aperture in a storage ring with space charge
The determination of dynamic aperture in storage rings and colliders is a numerically intensive procedure. When realistic space-charge forces come into consideration, the numerical load becomes even heavier. Furthermore, dynamic aperture estimation using chaos indicators like frequency map analysis (FMA) raises reliability issues when the dynamical system has a time-dependent perturbation like the space-charge force. In this article, we apply a rapidly converging chaos indicator called reversibility error method (REM) to study the space-charge contribution to the dynamic aperture of the integrable optics test accelerator (IOTA) storage ring at a small value of the space charge tune shift. The strength of REM is addressed through examples, including a particle-core model of halo formation. We also develop a toy model of the IOTA lattice to further reduce the computing time required to estimate the dynamic aperture, and we compare this model with a realistic space-charge simulation for verification.
Journal Article
Lorentz Violation by the Preferred Frame Effects and Cosmic and Gamma Ray Propagation
The ‘relativity with a preferred frame’, designed to reconcile the relativity principle with the existence of the cosmological preferred frame, incorporates the preferred frame at the level of special relativity (SR) while retaining the fundamental spacetime symmetry, which, in the standard SR, manifests itself as Lorentz invariance. In this paper, the processes, accompanying the propagation of cosmic rays and gamma rays through the background radiation from distant sources to Earth, are considered on the basis of particle dynamics and electromagnetic field dynamics developed within the framework of the ‘relativity with a preferred frame’. Applying the theory to the photopion-production and pair-production processes shows that the modified particle dynamics and electrodynamics lead to measurable signatures in the observed cosmic and gamma-ray spectra which can provide an interpretation of some puzzling features found in the observational data. Other processes responsible for gamma-ray attenuation are considered. It is found, in particular, that electromagnetic cascades, developing on cosmic microwave background and extragalactic background light, may be reduced or suppressed due to the preferred frame effects which should influence the shape of the very high-energy gamma-ray spectra. Other possible observational consequences of the theory, such as the birefringence of light propagating in vacuo and dispersion, are discussed.
Journal Article