Distribution Of Dust Particles Research Articles

A self-consistent model for dust settling and the vertical shear instability in protoplanetary disks

Abstract The spatial distribution of dust particles in protoplanetary disks affects dust evolution and planetesimal formation processes. The vertical shear instability (VSI) is one of the candidate hydrodynamic mechanisms that can generate turbulence in the outer disk region and affect dust diffusion. Turbulence driven by the VSI has a predominant vertical motion that can prevent dust settling. On the other hand, the dust distribution controls the spatial distribution of the gas cooling rate, thereby affecting the strength of VSI-driven turbulence. Here, we present a semi-analytic model that determines the vertical dust distribution and the strength of VSI-driven turbulence in a self-consistent manner. The model uses an empirical formula for the vertical diffusion coefficient in VSI-driven turbulence obtained from our recent hydrodynamical simulations. The formula returns the vertical diffusion coefficient as a function of the vertical profile of the cooling rate, which is determined by the vertical dust distribution. We use this model to search for an equilibrium vertical dust profile where settling balances with turbulent diffusion for a given maximum grain size. We find that if the grains are sufficiently small, there exists a stable equilibrium dust distribution where VSI-driven turbulence is sustained at a level of αz ∼ 10−3, where αz is the dimensionless vertical diffusion coefficient. However, as the maximum grain size increases, the equilibrium solution vanishes because the VSI can no longer stop the settling of the grains. This runaway settling may explain highly settled dust rings found in the outer part of some protoplanetary disks.

Simulation and synoptic investigation of a severe dust storm originated from the Urmia Lake in the Middle East

Dried lake beds are one of the largest sources of dust in the world, causing environmental problems in the surrounding areas. In this study, the desiccated Urmia Lake was the primary source of dust for all nearby synoptic stations during the April 24-25, 2017 dust episode. Synoptic analysis revealed that the heavy dust storm was triggered by a strong Black Sea cyclone and a low-pressure system over central Iraq in conjunction with a vast high-pressure system. HYSPLIT-based trajectory analysis showed that high PM10 recorded over the Urmia Lake region on April 23-26, 2017, influenced western Azerbaijan, the south of the Caspian Sea, southwestern Kazakhstan, northwestern Uzbekistan, and western Turkmenistan. The dustiest air masses (PM10 > 400 µg m–3) affected the south of the Caspian Sea and western Azerbaijan. Furthermore, the WRF-Chem model was run to evaluate the spatial distribution of dust particles in the study region. The vertical profile revealed that the simulated dust concentration ascended to 5 km from the lake. The WRF-Chem dust schemes accurately simulated dust propagation and the vertical dust profile over Urmia Lake; however, the AFWA and GOCART dust schemes showed that PM10 fluctuating changes were earlier than the measured surface PM10 at five stations around Urmia Lake on April 23-26, 2017. Furthermore, the maximum amount anticipated by the model simulation was 12 h earlier than the maximum surface mass concentration of measured PM10 at the stations throughout the period.

Granulometric characterization of Arctic driftwood sawdust from frame sawing process

Arctic driftwood can be used as an alternative source of wood as construction timber and furniture material, especially in Iceland and Greenland. The use of Arctic driftwood can help in the fight against climate change, by developing land reforestation processes and reducing the volume harvested wood from forests and sustainability of harvesting processes. In this paper the results of an analysis of the effect of long-term residence of pine (Pinus sylvestris L.) and larch wood (Larix sibirica L.) stay in Arctic ice and seawater on the granulation of wood sawdust and the distribution of fine wood dust particles during the frame sawing process are presented. The distribution of wood chips and dust was analysed using sieve and laser diffraction methods. The results confirmed that Arctic driftwood, compared to normal wood for both analysed species, generate slightly more fine wood dust particles during the frame sawing process, which can be harmful to human health. However, these differences are not significant, indicating that the same dust extraction systems can be used for both sawing processes.

Experimental analysis of dust composition impact on Photovoltaic panel Performance: A case study

Solar Photovoltaic systems are greatly influenced by meteorological conditions of the surrounding area, dust is the most influencing one. Dust deposition on the surface of photovoltaic (PV) panel hinder the penetration of solar radiation to PV cells and eventually reduce the power production of PV system. To overcome dust-based power losses, frequent cleaning is required depending on geographical location, PV integration scheme and size of the PV power plant. In this manuscript, consequences of dust deposition on photovoltaic systems such as drop in radiation and output power operating are studied, and the optimal time interval for cleaning is determined. Airborne dust particles were collected for a month for morphological and meteorological characterization. The average mass concentrations of the sample are 187.63 μgm-3, showcasing an irregular distribution of dust particles having unlike shapes and sizes. In this study, the influence of dust deposition is quantified using temperature and insolation for clean and dirty PV panels. The overall performance of the PV system is studied based on a comparison of quantified and recorded data. Lastly, different cleaning methodologies are studied to procure the best ones. Power losses were brought down to 7% when PV panels were cleaned fortnightly, which is the most feasible interval in terms of balance between cleaning cost and energy wasted due to soiling.

Exploring the potential of heat transfer and entropy generation of generalized dusty tetra hybrid nanofluid in a microchannel

Caputo–Fabrizio time-fractional derivatives are the subject of this paper. This article generalizes the concept of dusty Tetra hybrid nanofluid moving freely via convection between infinite vertical parallel static plates. Free convection and buoyant force cause the flow and transmit the heat. In addition, there is a consistent distribution of spherical dust particles over the whole flow. It is the temperature difference between the two regions that sets off free convection. Free convection takes heat transfer into account. The dust Tetra hybrid nanofluid classical model employs non-dimensional variables to achieve a dimensionless form. We also convert the dimensionally-free model into a fractional generalized dusty Tetra hybrid nanofluid model. In this paper, we use the finite sine approach to analytically solve the governing equations of the generalized Dusty Tetra hybrid nanofluid model. In this article, we generalize the concept of a dust-filled Tetra hybrid nanofluid freely flowing between infinite vertical parallel plates. We found an analytical solution to the governing equations for the generalized dusty Tetra hybrid nanofluid by combining the Finite Sine Fourier and Laplace transforms. Understanding the mechanics of velocity and temperature profiles requires the use of numerical computation for a variety of embedded factors. In-depth statistical analysis and charting of data are features of this investigation. Using Mathcad-15, we plot the profiles of the Tetra hybrid nanofluid, dust particles, and temperatures to see the findings physically. Also determined are the skin friction and Nusselt number. The rate of heat transfer decreases with time, as seen in Table 1. Similarly, as seen in Table 2, raising the fractional parameter results in a higher skin friction. In addition, the energy profile of both velocities increases with increasing tetra hybrid nano fluid volume percent, albeit the fraction's contribution decreases with time. Since the fractional models are more accurate, they also provide more potential outcomes. When all the facts are considered, these choices may out to be the best.

Design and comparison of a suitable dust separation technique during the machining process in a CNC machining center

Design and comparison of a suitable separation technique during the machining process in a CNC machining center. The paper deals with the issue of chip extraction from the milling process in a CNC machining center. The paper aimed to compare the particle size distribution of dust generated in the milling process of natural wood (beech, oak, and spruce) and MDF on a 5-axis CNC machining center. The particle size distribution was evaluated using sieve analysis of samples from the total weight of the captured dust. The results showed that the processing of natural wood is mainly characterized by the formation of coarse dust fractions (2 mm - 1 mm sieves), while the processing of MDF was associated with the formation of fine dust fractions with a size below 100 μm. Another of the objectives was to compare the separation values on the fractional separation curves of selected mechanical separators and filters with the size distribution of dust particles and to propose a suitable separation technique that meets the criteria of "best available technique" (BAT) in the processing of natural wood and MDF, as well as to point out the creation of and the production of harmful dust fractions, which arise mainly during the processing of MDF. We intended to assess whether the introduction of the given technology with the given material mix will also require modifications on the side of the extraction device.

Distribution of micro-sized range solid particles in the human airways: field experiment

Introduction. Ambient air pollution is a widespread and pressing issue. This necessitates the development of methods for estimating and predicting progression of pathologies on the base of evolutionary mathematical models. Adaptation of the theoretical model to practice requires identification and verification procedures in real conditions of contamination of inhaled air with dust particles of various compositions.
 The purpose of the work was to investigate regularities of distribution of dust particles with a different disperse, component and morphological structure in the human airways after inhalation from ambient air. The study involved performing a field experiment.
 Materials and methods. We accomplished several investigations in 3 zones with different levels and structures of ambient air pollution. Disperse, component, and morphological structures of particles occurring in ambient (inhaled), deposited in various sections of the human airways, in exhaled air and blood were examined by electronic microscopy.
 Results. Air quality in zones 1 and 2 did not comply with hygienic standards for suspended particles, PM10, PM2.5, metal compounds, etc. (up to 3.29 MPCm.s., 3.2 MPCav.s., 2.91 MPCav.y.) and formed increased hazard quotient for manganese, copper, nickel and their compounds, inorganic fluorides, suspended particles (up to 5.48 HQac, 3.42 HQch), respiratory and other hazard indices (up to 5.48 HIac, 8.59 HIch). The degree of sedimentation of small particles (PM2.5 or less) in different parts of the respiratory tract is uneven, they are able to penetrate into the lower airways and lungs of humans. More than 65% of all the particles deposited in the upper airways had a diameter bigger than 10 µm. PM2.5 accounted for more than 60 % in sputum in the lower airways and the share of PM1.5 reached 46.7 %. Particles smaller than 1.5 μm (90.5%) were predominantly recorded in blood biosubstrates, of which up to 88.1% of the particles had a sphericity of 0.9–1.0.
 Limitations. Limited degree of precision of location of the examined sections in the respiratory system.
 Conclusion. Common deposition regularities are mostly determined by sizes and morphology of dust particles. The component structure of inhaled air has practically no effects on regularities of particle deposition in various sections of the respiratory system; however, it can have substantial influence on types of pathologies progressing in the body. High shares of PM1.5 identified in inhaled air, the lower airways and blood require considering levels of PM1.5 and smaller particles in ambient air in settlements to be covered by hygienic standards. In future, the study results will be used in numeric modelling of accumulation of functional respiratory disorders and associated pathologies of other organs and systems and in predicting development of pathologies based on evolution mathematical models.

Study on dust distribution in a highway tunnel during the full-face excavation with Drilling-Blasting method

Dust problem is serious in a highway tunnel during the full-face excavation, particularly after blasting of tunnel face. In order to solve the problem of dust pollution after blasting effectively, this study investigated the space–time evolution law of dust and inhalable particles within 100 s after blasting under blowing ventilation. First, the Euler-Lagrange method is used to simulate the coupled motion of air and dust. Then, the influences of air velocity on the distribution of dust and inhalable particles are considered, and the simulation results are verified by field measured data. The present study indicated that the heavier particles in the dust produced by blasting of tunnel face are deposited at the bottom of wind-return side in front of duct. The inhalable particles which particle size less than or equal to 10 μm are more uniformly dispersed in the whole tunnel space, and the higher the air velocity, the shorter the time required for the process. In addition, by analyzing and fitting the particle moving distance along the length of tunnel, the approximate time required for dust to migrate to a certain location can be predicted. The prediction of space–time evolution law of dust and inhalable particles in this study can provide some guidance for practical engineering cleaner production.

Experimental study of particle deposition on a solar photovoltaic panel based on the response surface method.

To explore the influence of different factors on particle deposition, four crucial factors, including particle size, wind speed, inclination angle, and wind direction angle (WDA), were considered, and the particle deposition concentration was used as the response variable for experimental research. In this paper, the Box‒Behnken design analysis method in the response surface method was used to conduct experiments. First, the element composition, content, morphology characteristics, and particle size distribution of dust particles were analyzed experimentally. The changes in wind speed and WDA were obtained through a month-long test measurement. Then, the effects of particle size (A), wind speed (B), inclination angle (C), and WDA (D) on the deposition concentration were examined utilizing a test rig. The test data were analyzed by using Design-Expert 10 software, and the results show that four factors have different degrees of influence on the particle deposition concentration, in which the inclination angle effect is the smallest. In the two-factor interaction analysis, the P values of AB, AC, and BC are all less than 5%, indicating that the correlation between the two-factor interaction term and the response variable is acceptable. In contrast, the correlation between the single-factor quadratic term and the response variable is weak. According to the analysis results of single-factor and double-factor interactions, the quadratic fitting formula of particle deposition influencing factors and deposition concentration was obtained, which could quickly and accurately calculate the variation trend of particle deposition concentration under different environmental conditions.

Cometary dust collected by MIDAS on board Rosetta

Context. The Micro-Imaging Dust Analysis System (MIDAS) atomic force microscope (AFM) on board the Rosetta comet orbiter has been dedicated to the collection and 3D topographical investigation of cometary dust in the size range of a few hundreds of nanometers to tens of micrometers with a resolution down to a few nanometers. Aims. We aim to catalog all dust particles collected and analyzed by MIDAS, together with their main statistical properties such as size, height, basic shape descriptors, and collection time. Furthermore, we aim to present the scientific results that can be extracted from the catalog, such as the size distribution and statistical characteristics of cometary dust particles. Methods. Through a careful re-analysis of MIDAS AFM images, we make a significant update and improvement to the existing MIDAS particle catalog, resulting in the addition of more particles and newly developed shape descriptors. The final product is a comprehensive list of all possible cometary dust particles detected by MIDAS. The catalog documents all images of identified dust particles and includes a variety of derived information tabulated one record per particle. Furthermore, the best image of each particle was chosen for subsequent studies. Finally, we created dust coverage maps and clustering maps of the MIDAS collection targets and traced any possible fragmentation of collected particles with a detailed algorithm. Results. The revised MIDAS catalog includes 3523 MIDAS particles in total, where 1857 particles are expected to be usable for further analysis (418 scans of particles before perihelion + 1439 scans of particles after perihelion, both after the removal of duplicates), ranging from about 40 nm to about 8 μm in size. The mean value of the equivalent radius derived from the 2D projection of the particles is 0.91 ± 0.79 μm. A slightly improved equivalent radius based on the particle’s volume coincides in the range of uncertainties with a value of 0.56 ± 0.45 μm. We note that those sizes and all following MIDAS particle size distributions are expected to be influenced by the fragmentation of MIDAS particles upon impact on the collection targets. Furthermore, fitting the slope of the MIDAS particle size distribution with a power law of a · rb yields an index b of ~−1.67 to −1.88. Lastly, based on the created dust coverage maps and clustering maps of the MIDAS collection targets, we determined the particle fragmentation ratio of 4.09 for nominal activity and 11.8 for the outburst, which underlines that parent particles with faster impact velocity are more likely to be fragmented during dust collection.

Analysis of Size Distribution, Chemical Composition, and Optical Properties of Mineral Dust Particles from Dry Deposition Measurement in Tenerife: Determined by Single-Particle Characterization

In this paper, individual particle analysis by automated scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) was used to assess the size-resolved information of composition, size distribution, complex refractive index, and mixing state of mineral dust aerosol particles collected using different passive and active samplers. In the study, over 120,000 particles from 53 samples were analyzed. Results show that dust particles are the dominating mineral particle type during this campaign, comprising different classes of silicates, Si-rich (quartz-like), Ca-rich (calcite-like), CaMg-rich (dolomite-like), and CaS-rich (gypsum-like). The results also show that there is no significant difference in composition between suspended and deposited dust particles. By using the particle composition, the size-resolved complex refractive index of dust particles was calculated. The real part of the refractive index varied between 1.71 and 1.53 for wavelengths in the range of 370 to 950 nm. The imaginary part of the refractive index, determined mostly by iron oxide, varied between 3.28×10−4 and 7.11×10−5 for wavelengths ranging from 250 nm to 1640 nm. In addition, the refractive index values showed a slight decrease with increasing particle size. We also analyzed the potential for buffering of the acid mobilization of iron by other dust compounds. For particles which contain both iron (Fe) and (unprocessed) calcium (Ca), acids that are able to dissolve insoluble Fe particles can react with the Ca particles before reacting with Fe, but eventually, with longer processing time, the Fe particles could be processed. By analyzing the ratio of sulfate mass to the total aerosol mass of individual particles, the mixing state of sulfate particles to the total dust particles was investigated. The analysis showed that the finer dust particles were associated with higher content of sulfate, while the coarse dust particles correspond to lower sulfate contents, revealing that only fine mode sulfate is more internally mixed with mineral dust aerosol particles.

Effect of Low-Thermal Treatment on the Particle Size Distribution in Wood Dust after Milling.

The thermal treatment of wood can improve the appearance of the wood product's surface, its dimensional stability, and resistance to fungal attacks. However, the heat treatment changes the technological properties of wood, making it a new engineering material. This work investigates the effect of the low-thermal treatment of birch wood (Betula pendula Roth.), European beech wood (Fagus sylvatica L.), and alder wood (Alnus glutinosa L.) on the fine dust particles creation during woodworking. The samples of thermally treated wood with temperatures commonly used for the change of wood colour (105, 125, and 135 °C) were compared with reference samples made of natural wood. All 12 variants of the tested woods were milled using the 5-axis CNC machining center (20 mm diamond cutter, rotational speed 18,000 rev·min-1, the depth of cut 3 mm, feed rates of 2, 4 and 6 m∙min-1). A sieving analysis method allowed measuring the dust particle size distributions in all dust samples. The experiment's result analysis points out that wood type, thermal treatment, and feed rate meaningfully affect the size distribution of dust particles. Compared to birch wood and beech wood, the milling of alder wood samples created a much higher content of the finest dust particles, with particle sizes smaller than 0.032 mm. Increased temperatures in thermal treatment increase the share of fine dust particles with sizes smaller than 0.125 mm, compared to wood in its natural state. Milling with a lower feed rate (2 m·min-1) creates finer dust than processing with higher feed rates (4 and 6 m·min-1). Generally, the milling of alder in a natural or thermally treated state is a source of fine dust particles, particularly at low feed speed-rate milling, compared to birch and beech wood. In general, these results indicate that the low temperature thermal treatment parameters attribute new technological properties to all thermally modified types of wood tested.

Two-dimensional fluid simulation of spatial distribution of dust particles in a capacitively coupled silane plasma

In this work, we develop a two-dimensional fluid model to study the spatial density distributions of dust particles in a radio frequency capacitively coupled silane plasma. Unlike those scenarios based on the one-dimensional fluid model, in this work, the nonuniformity of the radial density distributions of dust particles is attributed mainly to the radial components of the electric field force and the ion drag force acting on the dust particles, leading to the two local density peaks near the electrode edges. It seems that dust particles tend to overcome the support of the electric field force and move much closer to the electrodes, as one of the density peaks indicates. Moreover, with the decrease of the radii of the discharge electrodes or the distance between them, the radial component of the ion drag force is enhanced, resulting in more dust particles gathering near the electrode edge region, and forming a ring-shaped particle density distribution. In the case of the discharge electrodes wrapped with dielectric materials, the uniformity of the radial density distributions of dust particles between the two electrodes is improved. Finally, the vortex motion of a single dust particle near the electrode edge region is also simulated in this work.

Modeling the dynamics of fine dust fraction in the surface layer of the atmosphere

We investigated the operating conditions of excavator equipment, leading to unsteady dynamics of dust far from the pollution source. Wind transport of dust takes into account the non-uniform vertical wind profile. Diffusion movement is also determined by the inhomogeneous coefficient of turbulent diffusion with a nonmonotonic dependence on height. The Earth’s surface is given by a digital elevation model, which allows calculations for a specific area with complex topography. Vertical inhomogeneities of wind and turbulence significantly change the nature of the spatial distributions of dust particles. Our approach makes it possible to determine changes in the disperse composition of particles with distance from the dust source.

Determination of the lifting height of dust particles after a mass explosion in an iron ore open pit

Open pit mining is accompanied by emissions of fine dust and hazardous gases into the atmosphere. This is related to the operation of open pit transport, drilling and blasting operations. The release of harmful components into the quarry space and the increase in their concentrations has a negative impact on the health of working personnel and leads to pollution of the environment. In doing so, the nature of fine dust and gases pollution depends on the mining technology and meteorological factors. The problem of reduced effectiveness of dust suppression methods after mass explosions in open pits is relate to insufficient research into the formation of dust and gas cloud. Additional theoretical and experimental research into the dust dynamics of blasting operations is therefore need. The article discusses the stages of formation of the dust and gas cloud after a mass explosion in an iron ore open pit. The results of experimental studies of the evolution of the dust and gas cloud at different points in time after the detonation of borehole charges are presented. Relations for determination of density and dynamic viscosity of gases, gas mixture and gas-dust aerosol are given. A formula for determining the time and height of ascent of spherical dust particles at the dynamic stage of dust and gas cloud formation is obtain. In this case, the assumption is madid that there is no mutual influence of the dynamic and thermal factors after detonation of the charges. The elevation of dust particles due to temperature differences during the heat stage of dust and gas cloud formation is determined. Based on the analysis of the calculation results, the duration of the dynamic stage of cloud formation is determined. It is established that, following the release of solid and gaseous detonation products into the atmosphere, a height distribution of dust particles is observed as a function of their diameter. That said during, the dynamic stage of dust and gas cloud formation, the height of dust particle lift is directly proportional to their diameter, while during the heat stage the inverse relationship is observe. That at the beginning of the thermal stage the deposition of coarse dust particles takes place are established. In this process, fine dust particles rise to a maximum height and are then carried outside the open pit by the airflow.

Mathematical modeling of the laws of airborne distribution of dust particles generated in manufacturing plants

In this article was given ideas on mathematical modeling of the laws of airborne distribution of dust particles generated in primary cotton processing plants, the laws of airborne distribution of various chemically harmful dust particles, as well as the physical variables of the air environment views on the modeling of dust particle dispersion processes in the working zone, such as stability, air flow rate, numerical values of indicators

Evaluation of aerosol optical depths and clear-sky radiative fluxes of the CERES Edition 4.1 SYN1deg data product

Abstract. Aerosol optical depths (AODs) used for the Edition 4.1 Clouds and the Earth's Radiant Energy System (CERES) Synoptic 1∘ (SYN1deg) product are evaluated. AODs are derived from Moderate Resolution Imaging Spectroradiometer (MODIS) observations and assimilated by an aerosol transport model (the Model for Atmospheric Transport and Chemistry – MATCH). As a consequence, clear-sky AODs closely match with those derived from MODIS instruments. AODs under all-sky conditions are larger than AODs under clear-sky conditions, which is supported by ground-based AErosol RObotic NETwork (AERONET) observations. When all-sky MATCH AODs are compared with Modern-Era Retrospective analysis for Research and Applications (Version 2; MERRA-2) AODs, MATCH AODs are generally larger than MERRA-2 AODs, especially over convective regions (e.g., the Amazon, central Africa, and eastern Asia). This variation is largely due to the differing methods of assimilating the MODIS AOD data product and the use of quality flags in our assimilation. Including AODs with larger retrieval uncertainty makes AODs over the convective regions larger. When AODs are used for clear-sky irradiance computations and computed downward shortwave irradiances are compared with ground-based observations, the computed instantaneous irradiances are 1 %–2 % larger than observed irradiances. The comparison of top-of-atmosphere clear-sky irradiances with those derived from CERES observations suggests that AODs used for surface radiation observation sites are 0.01–0.03 larger, which is within the uncertainty of instantaneous MODIS AODs. However, the comparison with AERONET AODs suggests that AODs used for computations over desert sites are 0.08 larger. The cause of positive biases in downward shortwave irradiance and in AOD for the desert sites is possibly due to the dust particle size and distribution, as defined by the MATCH transport model, and the transfer of that information into the radiative transfer model.

Radial distribution of the carbonaceous nano-grains in the protoplanetary disk around HD 169142

Context. HD 169142 is part of the class of (pre-)transitional protoplanetary disks showing multiple carbon nanodust spectroscopic signatures (aromatic, aliphatic) dominating the infrared spectrum. Precise constraints on the spatial distribution and properties of carbonaceous dust particles are essential to understanding the physics, radiative transfer processes, and chemistry of the disk. The HD 169142 disk is seen almost face-on and thus it offers a unique opportunity to study the dust radial evolution in disks. Aims. We investigate the spatial distribution of the carriers of several dust aromatic emission features of the disk across a broad spatial range (10–200 AU) as well as their properties. Methods. We analysed imaging and spectroscopic observations in the 8–12 µm range from the VLT Imager and Spectrometer for mid-Infrared (VISIR) at the Very Large Telescope (VLT), as well as adaptive optics spectroscopic observations in the 3–4 µm range from the Nasmyth Adaptive Optics System – Near-Infrared Imager and Spectrograph (NACO) at VLT. The data probe the spatial variation of the flux in the 3.3 µm, 8.6 µm, and 11.3 µm aromatic bands. To constrain the radial distribution of carbonaceous nano-grains, the observations were compared to model predictions using The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS), which is integrated into the POLARIS radiative transfer code by calculating the thermal and stochastic heating of micro-and nanometer-sized dust grains for a given disk structure. Results. Our data show predominant nano-particle emission at all radii (accessible with our resolution of about 0.1″ or ~12 AU at 3 µm and ~0.3″, 35 AU at 10 µm) in the HD 169142 disk. This unambiguously shows that carbonaceous nano-grains dominate radiatively the infrared spectrum in most of the disk, a finding that has been suggested in previous studies. In order to account for both VISIR and NACO emission maps, we show the need for aromatic particles distributed within the disk from the outermost regions to a radius of 20 AU, corresponding to the outer limit of the inner cavity derived from previous observations. In the inner cavity, these aromatic particles might be present but their abundance would then be significantly decreased.

Review of research on lunar dust dynamics

Lunar dust particles are generated by hypervelocity impacts of interplanetary micrometer meteoroids onto the surface of the Moon, which seriously threatens the security of explorations. Studying the lunar dust dynamics helps to understand the origin and migration mechanism of lunar dust, and to provide the theoretical guidelines for the orbital design of lunar space missions. This paper reviews previous research on the lunar dust dynamics, including the interplanetary impactor environment of the Earth–Moon system, the mass production rate, the initial mass, speed and ejecta angle distributions, the related space exploration missions, the dynamical model, and spatial distribution of dust particles originating from the lunar surface in the whole Earth–Moon system.

Spatial distribution of aerosol and dust man-made emissions in external influence zone of metallurgical enterprises

The study presents the method for calculating the distribution of dust and aerosol particles entering the external air environment as a result of man-made emissions of metallurgical cycle enterprises. The paper proposes the method for predicting the degree of pollution of the enterprises influence zones by constructing geographical maps-schemes of industrial regions with application of the areas with a high content of dust particles on them. This method is based on determination of the sedimentation time of dust particles of different fractions in atmospheric air using Stokes’ law (motion of solid particles in liquid or gaseous media), the height of dust particles departure from the chimney and the speed of prevailing wind over the studied period of time. The data necessary for the analysis (wind direction, amount of dust emitted, its fractional and chemical compositions) were found in open sources, reports of the enterprise, statistical data of the region and the metallurgical industry. An estimated calculation of the spread of dust emissions was carried out on the example of the Magnitogorsk Iron and Steel Works PJSC (MMK) during various annual seasons. It was found that the influence of activity of a metallurgical enterprise in Russia can adversely affect cities and residents of neighboring states that are located in the sedimentation zone of solid dust particles. The issue of transfer of sulfuric and nitric acids by dust particles formed in the pores of aerosol particles is considered. The authors calculated the amount of acid that can be carried into the zones of influence of the enterprise in the pores of solid dust particles. The considered calculation model makes it relatively quick and easy to assess the influence zone of the enterprise, assess risks and take measures to modernize, optimize the production process or aspiration systems.