Number Of Dust Particles Research Articles

Shear rheology of confined double rings of dust particles in a dusty plasma

Abstract Shear rheology is a fundamental property of soft matter, which can be deformed. Although the shear rheology of fluids has been well studied at the macroscopic scale, understanding the microscopic processes of rheology at the single-particle level remains a challenging issue. Dusty plasma serves as an ideal platform for exploring microscopic dynamics of system at the individual particle level. Here, we study the shear rheology of confined double rings of strongly coupled dust particles in a dusty plasma. The outer ring is actively driven to rotate using laser illumination. Depending on the particle number, the inner ring may passively rotate following the outer ring at different angular speeds, resulting in shear rheology. The number of dust particles influences particle arrangement, which is characterized by the pair correlation function, bond-orientational order parameter, and triangle skewness. That further alters structural stability, significantly affecting the shear rheology.

Fuzzy Evaluation Model for Operational Performance of Air Cleaning Equipment

Global warming has led to the continuous deterioration of the living environment, in which air quality directly affects human health. In addition, the severity of the COVID-19 pandemic has further increased the attention to indoor air quality. Indoor clean air quality is not only related to human health but also related to the quality of the manufacturing environment of clean rooms for numerous high-tech processes, such as semiconductors and packaging. This paper proposes a comprehensive model for evaluating, analyzing, and improving the operational performance of air cleaning equipment. Firstly, three operational performance evaluation indexes, such as the number of dust particles, the number of colonies, and microorganisms, were established. Secondly, the 100(1− α)% upper confidence limits of these three operational performance evaluation indexes were deduced to construct a fuzzy testing model. Meanwhile, the accumulated value of ϕ was used to derive the evaluation decision-making value. The proposed model can help companies identify the key quality characteristics that need to be improved. Furthermore, the competitiveness of cooperative enterprises towards smart manufacturing can be strengthened, so that enterprises can not only fulfill their social responsibilities while developing the economy but also take into account the sustainable development of enterprises and the environment.

Parameters of dust particle chains levitated vertically in a gas discharge plasma

The structural parameters of the dust particle chains suspended vertically in the electric field of a gas discharge are studied here. The investigations are performed by a numerical multi-block model based on a mean field approximation. The model describes the movement of ions and dust particles under the action of an external electric field, the electric field (Coulomb) of each charged dust particle, and the field of bulk plasma charge (ions and electrons) that screens the charges of dust particles. The gravity and the ion drag forces acting on the dust particles are also taken into account. Self-consistent chain parameters are calculated and compared for different number (1, 3, 5, and 7) and two different diameters (3.4 and 8.94 mcm) of dust particles in the chains. It is shown that an “ion wake” is formed behind the dust structures, and it grows with the number of dust particles and their size. With an increase in the number of dust particles in the chain, the charge of the first (top) dust particle increases. In the case of small dust particles, with an addition of new particles into the chain, the centers of the chains almost remain at the position of a single particle in the vertical direction. The chains of big dust particles move as a whole down in the direction of gravity with an increase in the number of particles.

Dust-gas coupling in turbulence- and MHD wind-driven protoplanetary disks: Implications for rocky planet formation

The degree of coupling between dust particles and their surrounding gas in protoplanetary disks is quantified by the dimensionless Stokes number. The Stokes number (St) governs particle size and spatial distributions, in turn establishing the dominant mode of planetary accretion in different disk regions. In this paper, we model the characteristic St of particles across time in disks evolving under both turbulent viscosity and magnetohydrodynamic (MHD) disk winds. In both turbulence- and wind-dominated disks, we find that collisional fragmentation is the limiting mechanism of particle growth. The water-ice sublimation line constitutes a critical transition point in dust settling, drift, and size regimes. For a fiducial disk evolution parameter α̃≃10−3, silicate particles inteior to the ice-line are characterized by low St (≲10−2) and sizes in the sub-mm- to 1cm-scale. Icy particles/boulders beyond the ice-line are characterized by high St (≳10−2) and sizes in the cm to dm size range. Hence, icy particles settle into a thin layer at the outer disk midplane and drift inward at velocities exceeding the gaseous accretionary flow due to substantial headwind drag. Silicate particles in the inner disk remain relatively well dispersed and are to a large extent advected inward with their surrounding gas.The St dichotomy across the ice-line translates to distinct planet formation pathways between the inner and outer disk. While pebble accretion proceeds slowly for rocky embryos within the ice-line (across most of parameter space), it does so rapidly for volatile-rich embryos beyond it, allowing for the growth of giant planet cores before disk dissipation. Through simulations of rocky planet growth, we evaluate the competition between pebble accretion and classical pairwise collisions between planetesimals. We conclude that the dominance of pebble accretion can only be realized in disks that are driven by MHD winds, slow-evolving (α̃≲10−3.5), and devoid of pressure maxima that may concentrate solids and give rise of planetesimal rings in which classical growth is enhanced. Such disks are extremely quiescent, with Shakura-Sunyaev turbulence parameters αν≲10−4. We conclude that for most of parameter space corresponding to values of αν reflected in observations of protoplanetary disks (≳10−4), pairwise planetesimal collisions constitute the dominant pathway of rocky planet accretion. Our results are discussed in the context of super-Earth origins, and lend support to the emerging view that they formed in planetesimal rings. Moreover, these results argue against a significant contribution (≳ 10%) of outer disk, carbonaceous material to the proto-Earth in the form of pebbles, in agreement with chemical and isotopic investigations of Earth’s accretion history.

Long-term dynamics around the Didymos–Dimorphos binary asteroid of boulders ejected after the DART impact

Context. In 2022, the DART mission spacecraft impacted the asteroid Dimorphos, the secondary body of the binary Didymos system, ejecting a large number of dust particles, rocks and boulders. The ESA Hera mission will reach the system in 2026 for post-impact studies and a possible detection of orbiting fragments. Aims. We aim to investigate the long-term dynamics of the large boulders ejected by DART to test if any of these objects survive in orbit until the arrival of the Hera mission. Methods. To model the dynamics of the boulders, we used a numerical model that includes the gravity of non-spherical Didymos and Dimorphos, the solar gravity, and the radiation pressure. The SPICE kernels are used to define the correct reference frame for the integrations. Results. The dynamics of the boulders is highly chaotic, and 1% of the initial boulders survive at least for four years on quasi-stable orbits. These orbits are characterised by wide oscillations in eccentricity in antiphase with those in inclination (including spin flips), a mechanism similar to the Kozai one. This behaviour may protect these bodies from close encounters with both asteroids. We also computed the distribution on the surfaces of the asteroids of sesquinary impacts, which may influence the dust emission (after the initial DART impact) and the surface composition of the asteroids. Conclusions. The probability of observing boulders by the mission Hera is small but non-negligible, and an almost constant flux of escaping boulders is expected in the coming years since their lifetime after the DART impact covers a large time interval. Most re-impacts on Dimorphos occur in the hemisphere opposite the impact site, preferentially close to the equatorial plane.

THRESHOLD EFFECT IN DUSTY CLUSTERS IN A MAGNETIC FIELD

The process of occurrence of rotational motion of dusty plasma in a longitudinal magnetic field was investigated. It was experimentally found that the occurrence of rotation depends on the number of dust particles in the direction perpendicular to the magnetic induction vector, as well as on their vertical position in the dust trap (i.e., the magnitude of the electric field). The value of the threshold for the appearance of rotation in the magnetic field at a constant number of particles depends on the particle size and discharge conditions. The parameters of the experiment are selected, at which the effect manifests itself in detail. It has been established that for stationary rotation, a stable position of dust particles in the cross section is required, which corresponds to the filling of the shells of a rotating dust structure.

Propagation characteristics of nonlinear dust acoustic solitary waves in complex plasma with nonthermal electrons and trapped ions

The propagation characteristics of nonlinear dust acoustic solitary waves in a complex plasma system with nonthermal electrons and trapped ions are investigate in this work. The nonlinear dispersion relation of dust acoustic waves is obtained by using the linear method, and the two-dimensional autonomous system governing the motion of nonlinear dust acoustic waves is derived by using the Sagdeev potential method. At the same time, the specific expression of the Sagdeev potential function is obtained based on the Sagdeev potential equation. The numerical simulations are used to analyze the phase portraits of the two-dimensional autonomous system, revealing the linear periodic wave orbits, nonlinear periodic wave orbits, and homoclinic orbits co-existing in the complex dusty plasma system with nonthermal electrons and trapped ions. Furthermore, from the variations of the Sagdeev potential function with different system parameters it follows that only the compressive solitary waves exist in this complex plasma system. The significant influences of various system parameters on the amplitude, width, and waveform of the nonlinear dust acoustic solitary wave in the complex plasma system are discussed in detail. The results demonstrate that the Mach number, the nonthermal electrons and trapped ions, undisturbed dust particle number density, temperature, and charge have important effects on the propagating characteristics of the nonlinear dust acoustic solitary waves in a complex plasma with nonthermal electrons and trapped ions.

Quantification of Dust Accumulation on Solar Panels Using the Contact-Characteristics-Based Discrete Element Method

Dust comprises particles usually present in the atmosphere. The deposition of dust on the surface of the solar panel seriously affects the light transmittance, resulting in lower pow-er generation efficiency and shortening the service life of the solar panel. Therefore, it is important to understand the dust distribution on the surface of solar panels and discuss the influence of dust on the power generation efficiency of solar panels for the efficient prevention of dust deposition on the panel. In this study, to analyze the dust distribution on the surface of the solar panel, the discrete element method was used to establish the contact mechanics model between dust particles and the solar panel. The number of dust particles on the surface of solar panels was calculated at different solar panel inclination angles, wind speeds, and wind directions. The wind speed of 1 and 3 m/s did not affect the dust deposition significantly but the speed over 5 m/s reduced the dust particles from the surface of the solar panel. The inclination angle of 23° influenced dust deposition on the surface of the solar panel. Wind direction did not show a significant effect on dust deposition. The longer the deposition time, the more particles remained on the surface due to the increased force between the particles and the surface of the solar panel. The results from calculation and measurement from transmittance were similar with a different rate of 3.41%. Thus, the result of the proposed calculation in this study provides a basis for de-signing the solar power generation plant and decision-making on the maintenance of the solar panel.

Spectral Simulation and Error Analysis of Dusty Leaves by Fusing the Hapke Two-Layer Medium Model and the Linear Spectral Mixing Model

The Hapke two-layer medium model is an efficient way of simulating the spectra of dusty leaves. However, the simulation accuracy is low when the amount of dustfall is small. To solve this problem, we introduced the dust coverage factor and the linear spectral mixing model, to improve the accuracy of the Hapke two-layer medium model. Firstly, based on the assumption of spherical dust particles, the arrangement and accumulation mode of the particles were set, and the coverage factor and accumulation thickness of particles in the leaf area were calculated. Then, the coverage factor was used as an abundance. Endmembers were the spectra of dust-free leaves (measured) and dust-covered leaves (simulated by model), and the final simulated spectra were calculated using linear spectral mixing theory. This study presents the following findings: (1) When the coverage factor was calculated using the exponential model, the maximum difference between the corrected simulated spectra and the measured spectra was 3.4%, and the maximum difference between the original simulated spectra and the measured spectra was 15.2%. The accuracy of the corrected spectra is much higher than that of the original simulated spectra. (2) In this study, the physical thickness and optical thickness calculated by the Hapke two-layer medium model are equivalent, which is quite different from the actual dust accumulation. When the linear spectral mixing model is introduced, to modify the simulation value when the number of dust particles accumulated is less than one layer, the spectral endmember value of the simulated dust leaf is replaced by the simulation spectrum when the number of dust particles accumulated is exactly one layer. The calculated cor-rection spectrum has high rationality and credibility. This finding may be beneficial for monitoring amounts of dustfall accurately using remote sensing in mining areas.

EVALUATION OF THE EFFICIENCY OF A MULTI-CHANNEL DUST COLLECTOR USING NUMERICAL SIMULATION

Multi-channel dust collectors are based on previously known designs of vortex dryers for bulk products. However, their use for air dust removal is promising. In earlier studies of these devices using numerical simulations, the dust capture coefficient was not evaluated, although it is the most important indicator of their efficiency. In this article, the numerical simulation of MCDC is carried out. The first stage of modeling is the calculation of the gas flow velocity and pressure fields in the device under study. At the second stage, a large number of trajectories of dust particles of different diameters were calculated with subsequent statistical processing. Dust capture coefficients and hydraulic loss coefficients were calculated. It is shown that for the reliability of the results of the numerical experiment, the number of dust particles should be at least 2000. To determine the effect of the outer half-shells on the efficiency of the device, these half-shells were discarded, as a result of which the multi-channel dust collector turned into a cyclone. The comparison of characteristics showed that, other things being equal, the devices being investigated have some advantages over cyclones in capturing of small fractions of dust. The hypothesis that the capture of particles in curved channels occurs mainly due to particle collisions with the front edges of metal half-shells was put forward and refuted. The results of numerical modeling do not support the hypothesis that some dust particles rotate along closed trajectories and form a filter for other particles. The formulas of other authors, which do not take into account the parameters of dust particles, are recognized as unworkable. The speculations of some authors about the influence of the Ranque-Hilsch vortex effect on the process of dust capture cannot be taken into account due to the low subsonic air velocities under the operating conditions of the apparatus.

Effects of dust particle number on the structure and dynamics in a binary complex plasma system by Langevin dynamics simulation

In this paper, Langevin dynamics simulation is used to study the influence of particle number on the structures and dynamics of a binary complex plasma, in which two kinds of particles with different masses are considered. The structures of the binary system are characterized by particle distribution, nearest-neighbor, and pair correlation function. The dynamics of the system are characterized by the evolution of average speed and kinetic energy as time, the mean square displacement (MSD) and self-diffusion coefficient of the binary particles. The lattice structures and the dynamics evolution of binary particles versus the particle number are investigated in detail in this paper. The space distribution shows that the binary particles easily fully separate themselves for a small particle number. The dynamics evolutions indicate that small particles reach the system center first, and then are pushed out by the later reached large particles. As the number of particles increases, the system becomes more ordered and the kinetic energy difference between the two kinds of particles becomes smaller. This study shows that the structure and dynamics of a binary complex plasma can be affected by dust particle number.

Weyl cosmology

The homogeneous and isotropic cosmological model in the Weyl conformal geometry is considered. We showed that, despite the conformal invariance, the dust matter is allowed in such a universe. It is shown that the number of dust particles is not conserved, i.e. they are continuously produced. The general form of the law for their creation is found.

An Enhanced VLC Channel Model for Underground Mining Environments Considering a 3D Dust Particle Distribution Model.

Underground Mining (UM) is a hostile industry that generally requires a wireless communication system as a cross-cutting axis for its optimal operation. Therefore, in the last five years, it has been shown that, in addition to radio-frequency-based communication links, wireless optical communications, such as Visible Light Communication (VLC), can be applied to UM environments. The application of VLC systems in underground mines, known as UM-VLC, must take into account the unique physical features of underground mines. Among the physical phenomena found in underground mines, the most important ones are the positioning of optical transmitters and receivers, irregular walls, shadowing, and a typical phenomenon found in tunnels known as scattering, which is caused by the atmosphere and dust particles. Consequently, it is necessary to use proper dust particle distribution models consistent with these scenarios to describe the scattering phenomenon in a coherent way in order to design realistic UM-VLC systems with better performance. Therefore, in this article, we present an in-depth study of the interaction of optical links with dust particles suspended in the UM environment and the atmosphere. In addition, we analytically derived a hemispherical 3D dust particle distribution model, along with its main statistical parameters. This analysis allows to develop a more realistic scattering channel component and presents an enhanced UM-VLC channel model. The performance of the proposed UM-VLC system is evaluated using computational numerical simulations following the IEEE 802.1.5.7 standard in terms of Channel Impulse Response (CIR), received power, Signal-to-Noise-Ratio (SNR), Root Mean Square (RMS) delay spread, and Bit Error Rate (BER). The results demonstrate that the hemispherical dust particle distribution model is more accurate and realistic in terms of the metrics evaluated compared to other models found in the literature. Furthermore, the performance of the UM-VLC system is negatively affected when the number of dust particles suspended in the environment increases.

Convergence of strong shock waves in an ideal gas with dust particles

In this paper, the authors study the problem of an imploding strong cylindrical/spherical shock wave collapsing at the axis/center of a cylindrical/spherical piston that is filled with a dusty gas of uniform density. The dusty gas is assumed to be a mixture of an ideal gas and a large number of dust particles. The dust particles are of a micrometric size and uniformly distributed in the mixture. A mathematical model using a system of hyperbolic partial differential equations is presented for the considered problem. The perturbation series method is used to solve the implosion problem, providing a global solution and yielding accurately the results of Guderley's local similarity solution, which holds only in the neighborhood of the axis/center of implosion. The values of all possible real similarity exponents and the corresponding amplitudes are determined in the vicinity of the shock collapse by extending the flow variables and shock location in the Taylor series in time t. Furthermore, the obtained values of similarity exponents have been compared with the existing results and numerical results obtained by the other methods. The effects of the adiabatic exponent γ, the wavefront curvature α, and various dusty gas parameters such as σ, Kp, and G0 on the shock trajectory and flow variables have been graphically analyzed.

Technical and technological foundations of soil cultivation in conditions of climate change

Purpose. To determine promising directions for the development of the technical and technological foundations of soil cultivation in the conditions of climate change. Methods. Monographic, abstract-logical, graph-analytical, induction and deduction, regression analysis of results. Results. Modern soil cultivation technologies are considered, their advantages and disadvantages, development trends are defined. It has been established that climate change will significantly affect the terms of execution of works, the conditions of interaction of working bodies of technical means with the soil environment. The parabolic relationship between traction resistance and soil moisture means that climate change will increase fuel costs for tillage. Therefore, the further search for new technical and technological solutions should be aimed at reducing energy consumption and preventing physical degradation of soils, substantiating structural and functional schemes of technical means for soil cultivation, parameters of working bodies and modes of operation, under which the number of dust particles in the surface layer of the soil will be minimal. Conclusions. The main direction of the development of the technical and technological base for the production of plant products in the conditions of climate change is the harmonization of the interaction of the working bodies of tillage machines with the soil, which will ensure the reduction of physical soil degradation and energy consumption to create a favorable environment for plant development and crop formation. In the conditions of global climate change, agricultural production is being reoriented towards precision farming systems, therefore, crop production technologies should be based on targeted tillage with the simultaneous introduction of a full dose of mineral nutrition into the seed sowing area for the planned harvest, sowing of seeds and preservation of plant residues on the surface of the soil for protection it from overheating and loss of moisture. Keywords: technical means, soil cultivation technologies, interaction of working bodies with the soil, soil moisture, soil resistance, energy consumption, physical soil degradation.

Control of dusty nanofluid due to the interaction on dust particles in a conducting medium: Numerical investigation

With ultra-high thermal significances, the nano-materials present some fundamental applications in many thermal engineering eras, mechanical and chemical engineering and modern technology. For sustainable development of industrial growth of a country, the enhancement in energy production and resources become one of the most fundamental challenges for scientists. This analysis presents the thermal aspects of dust nanoparticles in a dusty nano-material for the interaction of transverse magnetic field come across an expanding surface. The conjunction of Maxwell model thermal conductivity influences the characteristic of thermal properties that is helpful to enrich the heat transport phenomena. A mathematical model is prepared by considering metal nano-material (copper and silver) in association with the conventional fluid water. The numerical treatment is deployed for the solution of the complex nonlinear problem characterized by dust phase material and fluid transformed governing equations. The transport of heat energy is affected by the transient behavior of the volume fraction, dust particle number density in conjunction with magnetic field. However, the key features of the outcomes for the characterizing parameters are lubricated through graphs and simulated numerical values for the rate coefficients are presented in table that leads to the validation work with the earlier investigation. An increment in heat transfer rate is noted with suspension of copper nanoparticles in the dusty fluid while heat transfer reduces in case of silver nanoparticles. The nanoparticles temperature enhanced with interaction parameter and specific heat ratio. The current analysis has a greater impact in bio-medical since i.e. the blood flow within the artery as well as several industrial and engineering applications. All these aspects depend upon the nanoparticles particle size therefore the dust and nanoparticles proposed here are spherical.

Characterization of dust collected in EAST after 2019 campaign

Dust presented in experimental advanced superconducting tokamak (EAST) with mixed plasma-facing materials has been collected and characterized for the first time. Dust at different positions in the vessel was collected by vacuum cleaner after the first experimental campaign in 2019. The shape, composition, and size of dust particles have been analyzed using different methods. About 80% of the total number of dust particles have size between 20 and 80 μm, and most of dust particles are spherical, while schistose shape, columnar and irregular shape were also found. With the help of energy-dispersive x-ray spectroscopy different elements of dust have been identified, which is generally consistent with the different plasma-facing components in EAST. Both x-ray fluorescence and inductively coupled plasma emission spectrometer are complementary methods for measuring the dust composition quantitatively. It was found that the major components of dust were lithium dust in the form of lithium carbonate and lithium hydroxide, which is due to the routine lithium wall conditioning during EAST operation.

Surface tension of Coulomb balls

Herein, we have calculated plasma parameters corresponding to those of a dc discharge in neon at 77 K temperature at self-organization of dense Coulomb balls with a dust particle number density of more than 4×1011m−3. To calculate the plasma parameters, we employed the fluid model of the positive column of the glow discharge with dust particles. The potential energy of the dust particle and the analogue of the surface tension coefficient of the Coulomb ball at neon pressures from 20 to 160 Pa have been obtained. For the obtained values of the surface tension coefficient analogue, a comparison with data obtained by other authors has been carried out.

On the Possibility of Dust Acoustic Perturbations in Martian Ionosphere

It is shown that the horizontal winds in Martian ionosphere, at the initial stage of their interaction with dusty plasma clouds at altitudes of about 100 km, can cause conditions for the excitation of dust acoustic waves due to the development of kinetic instability. The dispersion relationship of the dust acoustic waves is determined as well as their growth rate in the conditions under study. It is noted that the generation time of the dust acoustic wave is substantially long to allow the formation of nonlinear plasma wave structures, e.g., solitons. Dust acoustic solitons that propagate in Martian ionosphere in the dusty plasma clouds at altitudes of about 100 km are studied. It is shown that the increase in dust particle number density or decrease in electron number density by one order of magnitude leads to the increase of the amplitude of dust acoustic solitons by one order of magnitude. The possibility of generation of dust acoustic perturbations in Martian ionosphere should be taken into account during processing and interpretation of observation data.

Configuration of the Martian dust rings: shapes, densities, and size distributions from direct integrations of particle trajectories

ABSTRACTIt is expected since the early 1970s that tenuous dust rings are formed by grains ejected from the Martian moons Phobos and Deimos by impacts of hypervelocity interplanetary projectiles. In this paper, we perform direct numerical integrations of a large number of dust particles originating from Phobos and Deimos. In the numerical simulations, the most relevant forces acting on the dust are included: Martian gravity with spherical harmonics up to fifth degree and fifth order, gravitational perturbations from the Sun, Phobos, and Deimos, solar radiation pressure, as well as the Poynting–Robertson drag. In order to obtain the ring configuration, simulation results of various grain sizes ranging from submicrometres to 100 μm are averaged over a specified initial mass distribution of ejecta. We find that for the Phobos ring grains smaller than about 2 μm are dominant; while the Deimos ring is dominated by dust in the size range of about 5–20 μm. The asymmetries, number densities, and geometric optical depths of the rings are quantified from simulations. The results are compared with the upper limits of the optical depth inferred from Hubble observations. We compare to previous work and discuss the uncertainties of the models.