Number Of Dust Particles Research Articles

Dynamical states in two-dimensional charged dust particle clusters in plasma medium.

The formation of dynamical states for a collection of dust particles in two dimensions is shown using molecular dynamics simulations. The charged dust particles interact with each other with a Yukawa pair potential mimicking the screening due to plasma. An external radial confining force has also been applied to the dust particles to keep them radially confined. When the particle number is low (say, a few), they get arranged on the radial locations corresponding to multiple rings or shells. For specific numbers, such an arrangement of particles is stationary. However, for several cases, the cluster of dust particles relaxes to a state for which the dust particles on rings display intershell rotation. For a larger number of dust particles (a few hundred, for instance), an equilibrium state with a coherent rigid body displaying angular oscillation of the entire cluster is observed. A detailed characterization of the formation of these states in terms of particle number, coupling parameter, etc., is provided.

Evaluation of WRF-Chem Predictions for Dust Deposition in Southwestern Iran

The relationships between monthly recorded ground deposition rates (GDRs) and the spatiotemporal characteristics of dust concentrations in southwest Iran were investigated. A simulation by the Weather Research and Forecasting Model coupled with the Chemistry modeling system (WRF-Chem) was conducted for dust deposition during 2014–2015. The monthly dust deposition values observed at 10 different gauge sites (G01–G10) were mapped to show the seasonal and spatial variations in dust episodes at each location. An analysis of the dust deposition samples, however, confirmed that the region along the deposition sites is exposed to the highest monthly dust load, which has a mean value of 2.4 mg cm−2. In addition, the study area is subjected to seasonally varying deposition, which follows the trend: spring > summer > winter > fall. The modeling results further demonstrate that the increase in dust emissions is followed by a windward convergence over the region (particularly in the spring and summer). Based on the maximum likelihood classification of land use land cover, the modeling results are consistent with observation data at gauge sites for three scenarios [S.I, S.II, and S.III]. The WRF model, in contrast with the corresponding observation data, reveals that the rate factor decreases from the southern [S.III—G08, G09, and G10] through [S.II—G04, G05, G06, and G07] to the northern points [S.I—G01, G02, and G03]. A narrower gap between the modeling results and GDRs is indicated if there is an increase in the number of dust particles moving to lower altitudes or an increase in the dust resident time at high altitudes. The quality of the model forecast is altered by the deposition rate and is sensitive to land surface properties and interactions among land and climate patterns.

Electrostatic interactions and stability of dusty plasmas and the multicomponent Ornstein–Zernike equation

Using the Ornstein–Zernike integral fluid equation for multi-component plasma, the dielectric properties and thermodynamical stability of dusty plasmas are studied. For the most non-ideal dust plasma subsystem, a transition to the one-component approximation is carried out. It is shown that the effective pseudopotential for determining the correlation functions in the selected subsystem should not include the contribution of this subsystem to the screening constant but also take into account the condition of total plasma quasineutrality. It is demonstrated that when the coupling parameter of the dust subsystem is smaller than unity, Γ00 < 1, the interaction potential between the charged plasma particles is fairly well described by the Debye potential with a full screening constant. For Γ00 > 1, the static dielectric function in the long wavelength domain becomes negative, and this domain expands when Γ00 increases. This leads to the appearance of attraction of particles with charges of the same sign and repulsion of particles with charges of the opposite sign. In this case, both the total pressure and the isothermal compressibility in the entire studied range of the coupling parameter Γ00 < 250 remain positive, but the isothermal compressibility of the dust subsystem becomes negative at Γ00 ≈ 2 within the studied range of variation of the plasma parameters. The sign of the derivative of the chemical potential with respect to the total number of dust particles, the positiveness of which is the third condition for the thermodynamic stability, is shown to coincide with the sign of the isothermal compressibility of the dust subsystem. Therefore, it is concluded that the equilibrium dusty plasma at Γ00 > 2 is thermodynamically unstable.

Oscillation-like diffusion of two-dimensional liquid dusty plasmas on one-dimensional periodic substrates with varied widths

The long-time diffusion of two-dimensional dusty plasmas on a one-dimensional periodic substrate with varying widths is investigated using Langevin dynamical simulations. When the substrate is narrow and the dust particles form a single row, the diffusion is the smallest in both directions. We find that as the substrate width gradually increases to twice its initial value, the long-time diffusion of the two-dimensional dusty plasmas first increases, then decreases, and finally increases again, giving an oscillation-like diffusion with varying substrate widths. When the width increases to a specific value, the dust particles within each potential well arrange themselves in a stable zigzag pattern, greatly reducing the diffusion and leading to the observed oscillation in the diffusion with the increase in the width. In addition, the long-time oscillation-like diffusion is consistent with the number of dust particles that are hopping across the potential wells of the substrate.

Catastrophic Events in Protoplanetary Disks and Their Observational Manifestations

Abstract Observations of protoplanetary disks with high angular resolution using an ALMA interferometer showed that ring-shaped structures are often visible in their images, indicating strong disturbances in the disks. The mechanisms of their formation are vividly discussed in the literature. This article shows that the formation of such structures can be the result of destructive collisions of large bodies (planetesimals and planetary embryos) accompanied by the formation of a large number of dust particles, and the subsequent evolution of a cloud of dust formed in this way.

Seasonal Variations and Long‐Term Trend of Dust Particle Number Concentration Over the Northeastern United States

AbstractMineral dust is known to affect cloud and precipitation by serving as ice nuclei, and an increasing number of modeling studies have explicitly related ice nucleation with the dust number concentrations. We examine the seasonal variations and the long‐term trend of dust number concentrations over the northeastern United States (NEUS) during 2000–2017, based on results from a global chemical transport model with size‐resolved particle microphysics (GEOS‐Chem/APM). Comparisons with observations show that GEOS‐Chem/APM can capture most of the strong dust events in the NEUS. The model results indicate that mineral dusts over the NEUS are dominated by dust transported in the lower and middle troposphere (from 2 to 6 km). The number concentrations of dust larger than 500 nm (ND,d > 500nm) vary by over 2 orders of magnitude from nondust‐transport days to event days, and ND,d > 500nm in different seasons can vary by 1 order of magnitude. The frequencies of dust events also show seasonal variation, with most annually top 50% dust events in spring and early summer (March–June) and in fall and early winter (September–December), and stronger dust events mainly in March–June. From 2000 to 2017, the springtime dust event days decrease by about 50% (above‐average dust events), 76% (top 10% events), and 85% (top 5% events), and ND,d > 500nm of strong events decreases by about 50%. Our analysis indicates that these decrease trends are caused by the declining Asian dust loading. The frequencies of dust events in summer have a weaker decreasing trend, and there is no obvious tendency in other seasons.

Absolute magnitude of small cosmic dust particles

ABSTRACT Agglomerated debris particles are realistic model cosmic dust particles that reproduce their highly irregular and fluffy morphology. We compute the absolute magnitude of these model particles in the broad-band filters B, V, R, and I from the widely used Johnson–Cousins photometric system. These data are aimed at providing simple quantitative interpretation of brightness of a cloud of cosmic dust, such as cometary coma, zodiacal light, lunar horizon glow, etc. Using this information, number of dust particles can be estimated from the apparent magnitude of the cloud and therefore the total volume of dust. It is significant that the smallest volume of dust is achieved using submicron particles.

Comparison of Dust Particle Dynamics Under Different Electrode Shapes at the Early Stage of Negative Corona Discharge

Electrode shape plays an important role in collecting efficiency of the arista electrode in electrostatic precipitation (ESP). Using hydrodynamic model coupled with Poisson’s equation and applying finite element method, the characteristics of Trichel pulse under hyperboloid electrode and hemispherical electrode were compared. The numerical model is established in dry air at atmospheric pressure, using a traditional needle-to-plane configuration, which is simplified from the model of arista electrode and a plate in ESP. Combined with the motion equation of dust particle, the motion characteristics of the dust particles at different positions in negative corona discharge with different electrode shapes are studied. Under the same average power, the anode of the hemispherical electrode collects more than twice as many dust particles as the hyperboloid electrode, and the number of dust particles attached to the cathode is a little less than that of the hyperboloid electrode, in the early stage of ESP.

Melting of strongly coupled, negatively charged, two‐dimensional dust cluster: The role of charge fluctuation amplitude

AbstractStructural and melting characteristics are investigated for negatively charged dust particles in the presence of a two‐dimensional electrostatic parabolic confinement potential. For a restricted number of dust particles that are subject to the permanent flow of electrons and ions, numerical simulation is conducted taking into account the random charge fluctuation. The amplitude of the charge fluctuation affects the ground‐state configuration and melting characteristics of a finite number of particles interacting through Coulomb potential. The melting temperature decreases when the amplitude of the charge fluctuation increases as a result of particles' strong repulsive interaction.

Electrical properties of cometary dust particles derived from line shapes of TOF-SIMS spectra measured by the ROSETTA/COSIMA instrument

Between Aug. 2014 and Sept. 2016, while ESA’s cornerstone mission Rosetta was operating in the vicinity of the nucleus and in the coma of comet 67P/Churyumov-Gerasimenko, the COSIMA instrument collected a large number of dust particles with diameters up to a millimeter. Positive or negative ions were detected by a time-of-flight secondary ion mass spectrometer (TOF-SIMS) and the composition of selected particles was deduced. Many of the negative ion mass spectra show, besides mass peaks at the correct position, an additional, extended contribution at the lower mass side caused by partial charging of the dust. This effect, usually avoided in SIMS applications, can in our case be used to obtain information on the electrical properties of the collected cometary dust particles, such as the specific resistivity (ρr>1.2⋅1010Ωm) and the real part of the relative electrical permittivity (εr<1.2). From these values a lower limit for the porosity is derived (P>0.8).

Health risk assessment for exposure to fine dust in production conditions

Introduction.The results of the study of the working area air during thermal insulation works are presented.The aim of the studywas to assess the health risk of workers in the construction industry and exposed to fine dust.Materials and methods.The number of dust particles of different dispersion in the air of the working area in the implementation of thermal insulation works is determined.Results.It is established that the working conditions during the thermal insulation works in accordance with the current regulatory documentation are classified as harmful 3 class 2 degree. Harmful factor of the production environment is dust (including PM10and fine PM2,5) in air of working zone (3.2). The air quality of the working area indicates a long stay of fine dust in the air over the territory of the construction site. Dust of different dispersed composition was found in the air of the working area during thermal insulation works. Th e dust concentration is more than 10 μm was 8.2±1.3 mg/m3, PM10and 1.8±0.4 mg/m3, PM2,5–1,25±0,2 mg/m3.Conclusions.The results obtained in the experiment make it possible to determine the safe duration of the working experience underthe influence of a harmful factor of the working environment (in terms of the permissible health risk) with different duration ofcontact with it during the day.

Evaluation of the ef ectiveness of alimentary correction of pathological changes in hepatic tissue under the inf uence of industrial copper-containing dust in the experiment

The results of comparative studies of the long-term ef ect (dynamics) of polymetallic dust containing 0.6% copper in the shops of Balkhash mining and metallurgical combine on the liver of rats are presented. These data on the action of dust with a predominant copper content of 0.6% give reason to assert that in the liver for 30 days there were changes in the structure, which were ref ected by metabolic rearrangements and are characterized as a failure of adaptation. The phenomena of hepatitis also took place on day 90, but these changes led to a decrease in the rate of metabolic processes. Microscopic examination showed that long-term exposure to polymetallic dust with a copper concentration of 0.6% in the body leads to signif cant changes in the liver reactive character, followed by transformation into hepatitis portal type. There is an accumulation of copper in the cytoplasm of hepatocytes; on day 90, the number of dust particles in rat hepatocytes increases by 2.25 times compared to 30 days of the experiment. T is can be explained by the inhibition of the phagocytic function of liver macrophages and ways to eliminate dust from the body. The lat er, in turn, leads to functional and metabolic damage to the structural component of the organ. It should be noted that an important role in the neutralization and removal of copper from the cell belongs to lysosomes. T ere is an assumption that copper damages lysosomal membranes and stimulates the release of enzymes from lysosomes due to a decrease in the number of mitochondria in the cell or inhibition of their enzymes. Thus, the ef ects of polymetallic dust with a copper concentration of 0.6% in the body in the early stages leads to changes in the liver, in the form of reactive hepatitis with subsequent transformation into portal-type hepatitis. The use of alimentary corrections slows down the development of post-necrotic f brosis in the liver, and there was a signif cant decrease in the volume fraction of f brotic liver tissue.

Ionization equation of state for the dusty plasma including the effect of ion–atom collisions

The ionization equation of state (IEOS) for a cloud of dust particles in the low-pressure gas discharge under microgravity conditions is proposed. IEOS relates pairs of the parameters specific for the charged components of dusty plasma. It is based on the modified collision enhance collection model adapted for the Wigner–Seitz cell model of the dust cloud. This model takes into account the effect of ion–atom collisions on the ion current to the dust particles and assumes that the screening length for the ion–particle interaction is on the same order of magnitude as the radius of the Wigner–Seitz cell. The included effect leads to a noticeable decrease of the particle charge as compared to the previously developed IEOS based on the orbital motion limited model. Assuming that the Havnes parameter of the dusty plasma is moderate, one can reproduce the dust particle number density measured in experiments and, in particular, its dependence on the gas pressure. Although IEOS includes no fitting parameters, it can ensure a satisfactory precision in a wide range of dusty plasma parameters. Based on the developed IEOS, the threshold relation between the dusty plasma parameters for onset of the lane formation in binary dusty plasmas is deduced.

Divergence of dust particles trajectories in dusty plasma model

The description of the properties of the plasma–dust system can be improved by using elements of thermodynamics. Divergence of the dusty particles trajectories allows us to estimate Krylov–Kolmogorov–Sinai entropy for a system of dust particles in plasma. In this way, we can verify if the behavior of the K-entropy of the dusty plasma subsystem in the partial equilibrium is close to the physical entropy. A picture of the divergence of trajectories for the dusty plasma model is obtained. The memory time of the model is estimated. The dependence of K-entropy on the number of dust particles and on the average kinetic energy of the dust particles are presented. The similarity of the behavior of the K-entropy parameter in the plasma–dust system and in the classical molecular-dynamic gas model is shown. The possibility of using this parameter for the description of dusty plasma is discussed.

Particle Growth in an Experimental Dusty Plasma System☆☆Supported by the National Natural Science Foundation of China under Grant No 11675261.

The coagulation and growth process of dust particles is investigated through laboratory experiment in a plasma system. A large number of dust particles with different sizes and shapes are formed. The growth process is characterized by the scattering laser intensity and fractal dimension. The comparisons of dust particles and scattering laser intensity obtained at different rf powers are presented. The three-dimensional distribution of dust particles is also given. These results provide an experimental basis for dust growth investigation.

Convective heat transfer in a dusty ferromagnetic fluid over a stretching surface with prescribed surface temperature/heat flux including heat source/sink

The aim of the present paper was to investigate the boundary layer flow and heat transfer in a dusty fluid with ferromagnetic particles over a flat stretching sheet including the effect of magnetic dipole. By using suitable similarity transformations, the governing partial differential equations of momentum and energy were reduced into non-linear ordinary differential equations. The resulting differential equations with corresponding boundary conditions were solved numerically by employing shooting based fourth order Runge-Kutta method. The effect of controlling parameters such as ferromagnetic interaction parameter, mixed convection parameter, Eckert number, Prandtl number, the number of dust particles and heat generation/absorption parameter on the temperature and velocity profiles are considered graphically for two types of heating processes, namely, the prescribed surface temperature (PST) and the prescribed heat flux (PHF). The value of skin friction coefficient and Nusselt number are presented in tabular form for different values of the governing parameters. It is found that the value of local Nusselt number increases with an increase of the value of heat source/sink parameter for both PST and PHF cases. The present results were compared with previously published data for a special case and an excellent agreement was found.

Compressed Air Quality, A Case Study In Paiton Coal Fired Power Plant Unit 1 And 2

The compressed air system becomes part of a very important utility system in a Plant, including the Steam Power Plant. In PLN’S coal fired power plant, Paiton units 1 and 2, there are four Centrifugal air compressor types, which produce compressed air as much as 5.652 cfm and with electric power capacity of 1200 kW. Electricity consumption to operate centrifugal compressor is 7.104.117 kWh per year. Compressed air generation is not only sufficient in quantity (flow rate) but also meets the required air quality standards. compressed air at Steam Power Plant is used for; service air, Instrument air, and for fly Ash. This study aims to measure some important parameters related to air quality, followed by potential disturbance analysis, equipment breakdown or reduction of energy consumption from existing compressed air conditions. These measurements include counting the number of dust particles, moisture content, relative humidity, and also compressed air pressure. From the measurements, the compressed air pressure generated by the compressor is about 8.4 barg and decreased to 7.7 barg at the furthest point, so the pressure drop is 0.63 barg, this number satisfies the needs in the end user. The measurement of the number of particles contained in compressed air, for particle of 0.3 micron reaches 170,752 particles, while for the particle size 0.5 micron reaches 45,245 particles. Measurements of particles conducted at several points of measurement. For some point measurements the number of dust particle exceeds the standard set by ISO 8573.1-2010 and also NACE Code, so it needs to be improved on the air treatment process. To see the amount of moisture content in compressed air, it is done by measuring pressure dew point temperature (PDP). Measurements were made at several points with results ranging from -28.4 to 30.9 °C. The recommendation of improving compressed air quality in steam power plant, Paiton unit 1 and 2 has the potential to extend the life of instrumentation equipment, improve the reliability of equipment, and reduce the amount of energy consumption up to 502,579 kWh per year.

Two-dimensional positive column structure with dust cloud: Experiment and nonlocal kinetic simulation

The influence of a dust cloud on the structure of the positive column of a direct current gas discharge in a cylindrical glass tube under milligravity conditions has been studied both experimentally and numerically. The discharge was produced in neon at 60 Pa in a glass tube with a diameter of 30 mm at a discharge current 1 mA. Spherical monodisperse melamine formaldehyde dust particles with a diameter of 6.86 μm were injected into the positive column and formed there a uniform dust cloud with a maximum diameter of 14.4 mm. The shape of the cloud and the dust particle number density were measured. The cloud was stationary in the radial direction and slowly drifted in the axial direction. It was found that in the presence of the dust cloud, the intensity of the neon spectral line with a wavelength by 585.25 nm emitted by the discharge plasma increased by 2.3 times and 2 striations appeared on the anode side of the cloud. A numerical simulation of the discharge was performed using the 2D (quasi-3D) nonlocal self-consistent kinetic model of a longitudinally inhomogeneous axially symmetric positive column [Zobnin et al., Phys. Plasmas 21, 113503 (2014)], which was supplemented by a program module performing a self-consistent calculation of dust particle charges, the plasma recombination rate on dust particles, and ion scattering on dust particles. A new approach to the calculation of particle charges and the screening radius in dense dust clouds is proposed. The results of the simulation are presented, compared with experimental data and discussed. It is demonstrated that for the best agreement between simulated and experimental data, it is necessary to take into account the reflection of electrons from the dust particle surface in order to correctly describe the recombination rate in the cloud, its radial stability, and the dust particle charges.

Attenuation characteristics of electromagnetic waves in a weak collisional and fully ionized dusty plasma

The expression of complex dielectric permittivity for non-magnetized fully ionized dusty plasma is obtained based on the kinetic equation in the Fokker–Planck–Landau collision model and the charging equation of the statistical theory. The influences of density, average size of dust grains, and balanced charging of the charge number of dust particles on the attenuation properties of electromagnetic waves in fully ionized dusty plasma are investigated by calculating the attenuation constant. In addition, the attenuation characteristics of weakly ionized and fully ionized dusty plasmas are compared. Results enriched the physical mechanisms of microwave attenuation for fully ionized dusty plasma and provide a theoretical basis for future studies.

Characteristics of traffic-induced fugitive dust from unpaved roads

ABSTRACTThe characteristics of fugitive dust emitted from vehicles traveling on unpaved dirt roads were measured using a suite of instruments including a real-time fugitive dust sampler. The fugitive dust sampler is formed from a combination of a large particle inlet and an optical particle spectrometer that reports particle sizes from 6 to 75 µm. The large particle inlet permits the sampling of particles up to 75 µm with only a moderate dependence of sampling efficiency on wind-speed. Measurements made with the sampler showed that particles as large as ∼50 µm were suspended from vehicular movement on the dirt roads, with the mode of the fugitive dust particle number size distribution ∼2 µm, while the mass distribution mode was ∼7 µm. A comparison of the fugitive dust sampler measurements with those made using standard PM instruments showed that the conventional instruments have a wind-direction bias that can result in under-sampling of large particles. The current measurements suggest that particles susp...