This paper presents a method of measuring the particle mean size and dust concentration by small angle near forward light scattering optics and the extinction theory. Its theory is based on Fraunhofer diffraction the...This paper presents a method of measuring the particle mean size and dust concentration by small angle near forward light scattering optics and the extinction theory. Its theory is based on Fraunhofer diffraction theory which is the approximation of Mie scattering within the forward Fraunhofer diffraction lobe, and Rosin Rammler function is introduced to describe the particle size distribution in two phase flow in advance. Compared with the values by the sample weight method, the measurement results have a reasonable agreement. The present work has demonstrated that this method will be probably used to monitor the parameters of two phase flow.展开更多
The investigation of dust particle characteristics in fusion devices has become more and more imperative.In the HL-2A tokamak,the morphologies and compositions of dust particles are analyzed by using scanning electron...The investigation of dust particle characteristics in fusion devices has become more and more imperative.In the HL-2A tokamak,the morphologies and compositions of dust particles are analyzed by using scanning electron microscopy（SEM） and energy dispersive x-ray spectroscopy（EDX） with mapping.The results indicate that the sizes of dust particles are in a range from 1 μm to 1 mm.Surprisingly,stainless steel spheres with a diameter of 2.5μm-30 μm are obtained.The production mechanisms of dust particles include flaking,disintegration,agglomeration,and arcing.In addition,dynamic characteristics of the flaking dust particles are observed by a CMOS fast framing camera and simulated by a computer program.Both of the results display that the ion friction force is dominant in the toroidal direction,while the centrifugal force is crucial in the radial direction.Therefore,the visible dust particles are accelerated toriodally by the ion friction force and migrated radially by the centrifugal force.The averaged velocity of the grain is on the order of^100 m/s.These results provide an additional supplement for one of critical plasma-wall interaction（PWI） issues in the framework of the International Thermonuclear Experimental Reactor（ITER） programme.展开更多
The effect of dust particles on electric contacts and a hazardous size range of hard dust particles using a rigid model were discussed before. As further research, elastic-plastic model of finite element analysis was ...The effect of dust particles on electric contacts and a hazardous size range of hard dust particles using a rigid model were discussed before. As further research, elastic-plastic model of finite element analysis was established in this work, which is closer to real condition. In this work, the behavior of large size and small size particles, and the influence of particles hardness were investigated. The calculating result of small-size particles presents a general hazardous size coefficient for different contact surface morphology; for large-size particles, it presents a hazardous size coefficient for complicated composition of the dust. And the effect of the dust shape is also discussed.展开更多
Despite international efforts to limit worker exposure to coal dust,it continues to impact the health of thousands of miners across Europe.Airborne coal dust has been studied to improve risk models and its control to ...Despite international efforts to limit worker exposure to coal dust,it continues to impact the health of thousands of miners across Europe.Airborne coal dust has been studied to improve risk models and its control to protect workers.Particle size distribution analyses shows that using spraying systems to suppress airborne dusts can reduce particulate matter concentrations and that coals with higher ash yields produce finer dust.There are marked chemical differences between parent coals and relatively coarse deposited dusts(up to _(500)μm,DD_(500)).Enrichments in Ca,K,Ba,Se,Pb,Cr,Mo,Ni and especially As,Sn,Cu,Zn and Sb in the finest respirable dust fractions could originate from:(i)mechanical machinery wear;(ii)variations in coal mineralogy;(iii)coal fly ash used in shotcrete,and carbonates used to reduce the risk of explosions.Unusual enrichments in Ca in mine dusts are attributed to the use of such concrete,and elevated K to raised levels of phyllosilicate mineral matter.Sulphur concentrations are higher in the parent coal than in the DD_(500),probably due to relatively lower levels of organic matter.Mass concentrations of all elements observed in this study remained below occupational exposure limits.展开更多
Charged photovoltaic glass produces an electrostatic field.The electrostatic field exerts an electrostatic force on dust particles,thus making more dust particles deposited on the glass.In this paper,the contact elect...Charged photovoltaic glass produces an electrostatic field.The electrostatic field exerts an electrostatic force on dust particles,thus making more dust particles deposited on the glass.In this paper,the contact electrification between the deposited dust particles and the photovoltaic glass is studied.Meanwhile,the surface charge density model of the photovoltaic glass and the electrostatic force of charged particles are analyzed.The results show that with the increasing of the particle impact speed and the inclination angle of the photovoltaic panel,the charges on particles increase to different degrees.Under a given condition,the electrostatic forces acting on the charged particles at different positions above the glass plate form a bell-shaped distribution at a macro level,and present a maximum value in the center of the plate.As the distance between the particle and the charged glass decreases,the electrostatic force exerted on the particle increases significantly and fluctuates greatly.However,its mean value is still higher than the force caused by gravity and the adhesion force,reported by some studies.Therefore,we suggest that photovoltaic glass panels used in the severe wind-sand environment should be made of an anti-static transparent material,which can lessen the dust particles accumulated on the panels.展开更多
This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densitie...This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densities,and identified the levels and sources of heavy metal contamination.The concentrations of Zn,Cu,Pb,Sb,and Cd except Mn in airborne particles,road dusts and soils were all in direct proportion to traffic volume.Cd concentrations were low compared with other metals.For instance,the concentrations of Zn,Cu,Pb,Sb,Mn and Cd were 6.6,0.7,2.2,0.1,0.1 and 0.1μg·m-3in PM10along the Changjiu Expressway,792.8,241.4,248.3,9.6,340.5and 8.0 mg·kg-1in road dusts,and 201.1,143.2,59.5,9.5,338.9 and 2.3 mg·kg-1in soils,respectively,but in the case of the ratio of concentration to the environmental background value,most serious contamination was caused by Cd.The sources of the heavy metals were judged by comparisons of the chemical forms of the heavy metals in different environmental media.Pb and Mn in airborne particles were both derived from traffic;Pb in road dusts and soils resulted mainly from the use of leaded gasoline in the past;and Mn in road dusts and soils was derived from parent rocks.Zn,Cu,Sb and Cd in airborne particles,road dusts and soils were derived primarily from traffic,and differences in chemical forms of the heavy metals in different media were due to the interaction between heavy metals in airborne particles and organic matter and other surfaces in road dusts and soils.We also discussed the change of chemical forms of heavy metals in particles of different sizes and under different weather conditions.Bioavailability of heavy metals in airborne particles was much higher than that in road dusts and soils,especially Pb(0.676 in airborne particles,0.159 in road dusts and 0.095 in soils).展开更多
An intense Asian dust storm invadedQinhuangdao,a coastal city ofNorth China on April 11-14,2023.We analyzed the bulk water-soluble inorganic ions(WSII)of PM_(10)and PM_(2.5)using an Ion Chromatograph and investigated ...An intense Asian dust storm invadedQinhuangdao,a coastal city ofNorth China on April 11-14,2023.We analyzed the bulk water-soluble inorganic ions(WSII)of PM_(10)and PM_(2.5)using an Ion Chromatograph and investigated individual particlemorphology and elemental composition using a scanning electron microscope coupled with energy dispersive X-ray.The results showed when the dust was directly transported to the sampling site from northwestern China(direct transport stages),the PM_(10)mass concentrations were high(675.0μg/m^(3))but the relative humidity(RH)was low.Total WSII were 19.54μg/m^(3)and 11.17μg/m^(3),accounting for 2.90%and 7.25%of the PM_(10)and PM_(2.5),respectively.In addition,the proportion of S-containing individual mineral dust was low(28.7%-35.3%).The results suggested there were limited secondary inorganic aerosol formation.However,when the dust was transported back to the sampling site across the Bohai Sea in the following days(reverse transport stages),both the PM_(10)mass concentrations(462.3μg/m^(3))and RH were high.Total WSII were 43.75μg/m^(3)and 18.71μg/m^(3),accounting for 9.62%and 14.45%of the total PM_(10)and PM_(2.5),respectively.The proportion of S-containing particles was 51.5%-72.5%.In addition,the concentration of NO_(3)^(−)was much higher than that of SO_(4)^(2−).The results suggested both the sulfate and nitrate formation occurred on coarse mineral dust but the nitrate formation exceeded sulfate formation.Interestingly,mostmineral dust,including Sirich particles contained Cl when they passed through the marine atmosphere.The results highlighted the heterogeneous reactions of dust varied in different transport stages.展开更多
Stationary electrostatic-potential formation in plasma with immovable dustparticles was investigated by using one-dimensional kinetic analysis. It is clarified that thedensity of negatively charged dust particles belo...Stationary electrostatic-potential formation in plasma with immovable dustparticles was investigated by using one-dimensional kinetic analysis. It is clarified that thedensity of negatively charged dust particles below the threshold value makes the potential decreasemonoton-ically. When the dust densities are above the threshold, there appears the stationaryoscillation in an electrostatic potential due to the streaming plasma. It is found that thewavelength of this mode is of the order of Debye length. These phenomena are different from those ofthe conventional dust ion-acoustic waves in plasma, where the effect of dust-charging is not takeninto account.展开更多
A large number of cosmic dust particles, micrometeorites and volcanic dust bands have been found and collected in Antarctic ice, snow and glacial sediments, especially in meteorite concentrated regions. Extraterrestri...A large number of cosmic dust particles, micrometeorites and volcanic dust bands have been found and collected in Antarctic ice, snow and glacial sediments, especially in meteorite concentrated regions. Extraterrestrial spherules also have been discovered from the stratosphere and deep-sea sediments. On the basis of their distributive characteristics the cosmic dust particles are classified into interplanetary dust particles and interstellar dust particles. According to their origins cosmic dust particles can be divided into cometary origin particles, asteroidal origin particles, ablation particles from meteorites and interstellar origin particles. The criteria for identifying cosmic dust particles have been established and the origins of cosmic dust particles are also discussed in aegis paper.展开更多
The seasonal transport of the Saharan dust to the West African region, near the Gulf of Guinea, during northem winter has been studied over 12 years. Using an optical particle counter, the dust aerosols in the diamete...The seasonal transport of the Saharan dust to the West African region, near the Gulf of Guinea, during northem winter has been studied over 12 years. Using an optical particle counter, the dust aerosols in the diameter range 0.5-25 μm have been sampled at Kumasi （6040＇ N, l°34＇ W） in Ghana during the winter months of January-February from 1997 to 2009. The settling atmospheric dust particles observed during the peak Harmattan and the background Harmattan periods are analysed for the mean particle size, number and mass concentrations as well as the particle size-frequency. It is shown that the average daily particle diameter, number and mass concentrations obtained in the peak Harmattan periods are 1.57 ± 0.54 μm, 50 ± 25 particles/cm3 and 1,130 ± 994 μg/m3, respectively, while for the background Harmattan these values are correspondingly, 1.31 ±0.31 μm, 32 ±12 particles/cm3 and 576 ±429 μg/m3, respectively. These experimental results will be useful for the design of ambient air-filters and for understanding the West African climate change.展开更多
The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characteriz...The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characterized by particle distribution, nearest neighbor configuration and pair correlation function. The current autocorrelation function, the dispersion relation and sound speed are used to represent the wave properties. The wave propagation of the dust lattice closely relates to the lattice structure. It shows that the number of defect particles can affect the dust lattice local structure and then affect the dispersion relations of waves propagating in it. The presence of defect particles has a greater effect on the transverse waves than on the longitudinal waves of the dust lattice. The appropriate number of defect particles can weaken the anisotropy property of the lattice.展开更多
The structure of the sheath in the presence of energetic particles is investigated in the multi-fluid framework. Based on the orbital motion limited（OML） theory, the dust grain charging inside the sheath of plasma c...The structure of the sheath in the presence of energetic particles is investigated in the multi-fluid framework. Based on the orbital motion limited（OML） theory, the dust grain charging inside the sheath of plasma containing energetic particles is examined for the carbon wall, and then the effect of the energetic particles on the stationary dust particle inside the sheath is discussed through the trapping potential energy. It is found that with the increase of energetic ion concentration or energy,the size of dust staying in levitation equilibrium decreases and the levitating position is much closer to the wall. In the case of deuterium ions as energetic ions, the bigger dust particle can be trapped by the sheath than in the case of hydrogen ions as energetic ions. When the energetic electron component is present, the levitating position of dust particle in the sheath depends strongly on the energetic electron. The levitating dust particle is closer to the wall as the energetic electron energy or concentration is increased. In addition, with the increase of temperature of thermal background ion, the size of dust particle trapped by the sheath decreases and the levitating positions of dust particles with the same size radius inside the sheath move toward the wall. Our results can be helpful in investigating the property of the sheath where the energetic particle component is present.展开更多
Fine particulates instead of others create particulate pollution and they are easier to escape from almost all conventional collectors of low- or medium-efficiency. It is of practical significance to take full advanta...Fine particulates instead of others create particulate pollution and they are easier to escape from almost all conventional collectors of low- or medium-efficiency. It is of practical significance to take full advantages of particle coagulation by electrostatic forces to upgrade the collertors' performance. This paper investigates the main mechanisms of coagulation, all possible electrostatic forces existing in the collectors and their effects on the particle coagulation. To make particle kinetic coagulation electrostatically enhanced be a step of the conventional collectors. operations,certain conditions should be created through some medifications of the collectors. Based on that ,the authors suggest that a precharger electro-cyclone technique be applied to improve the performance of common cyclones still widely used in many places. And a preliminary semi-industrial test has been carried out at Jiawang Power Station, Xuzhou, Jiangsu Province, and the results show that the modified cyclone increases its efficiency from about 80% to 92~94%.展开更多
The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffrac...The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The results show that the HBD particles can be classified into three types based on their particle size(PS):larger particles(PS>10μm),medium particles(1μm≤PS≤10μm),and nanoparticles(PS<1μm).The cumulative volume of respirable dust(PS≤10μm)was 84.45%.In addition,three shapes of HBD were observed by SEM:prism,flake,and bulk.In particular,the small particles were mostly flaky,with a greater possibility of being inhaled.Furthermore,the body and surface chemical compounds of HBD were determined by XRD and XPS,respectively.Ammonium adipate(C6H16N2O4)was the only organic compound in the body of HBD,but its mass fraction was only 13.4%.However,the content of organic C on the surface of HBD was 85.35%.This study demonstrated that the small-particle size and large amount of organic matter on the surface of HBD are the main reasons for its hydrophobicity,which can provide important guidance for controlling respirable dust in iron mines.展开更多
Particles of dust washed off streets by stormwater are an important pathway of polyaromatic hydrocarbons （PAHs） into urban streams. This article presented a comprehensive assessment of the size distribution of PAHs ...Particles of dust washed off streets by stormwater are an important pathway of polyaromatic hydrocarbons （PAHs） into urban streams. This article presented a comprehensive assessment of the size distribution of PAHs in street dust particles, the potential risks of the particles in urban streams, and the sources and sinks of PAHs in the stream network. This assessment was based on measurements of 16 PAHs from the USEPA priority list in street dust particles and river sediments in Xincheng, China. The content of total PAHs ranged from 1629 to 8986 Dg/kg in street dust particles, where smaller particles have a higher concentrations. Approximately 55% of the total PAHs were associated with particles less than 250 μm which accounted for 40% of the total mass of street dust. The PAH quantities increased from 2.41 to 46.86 μg/m2 in the sequence of new residential, rising through main roads, old town residential, commercial and industrial areas. The sediments in stream reaches in town were found to be sinks for street dust particle PAHs. The research findings suggested that particle size, land use and the hydrological conditions in the stream network were the factors which most influenced the total loads of PAH in the receiving water bodies.展开更多
Recent observations of Asian dust storms show an eastern expansion of the source area to degraded lands, where dust emissions have been little studied. The dust concentrations over the saline land of the western Songn...Recent observations of Asian dust storms show an eastern expansion of the source area to degraded lands, where dust emissions have been little studied. The dust concentrations over the saline land of the western Songnen Plain （SSL）, Northeastern China, are circumstantially higher than those from the northwestern Chinese deserts. These concentrations are sensitive to the surface soil conditions and wind velocity on the ground. The dust samples collected during dust storm events on the SSL contain abundant Na, Mg, A1, K, Ca, Fe and Ti, as well as toxic elements such as Cu, V, Zn and Ba. Individual particle analysis reveals that fine saline particles （〈 10 μm in diameter） on the saline land, consisting largely of carbonate, halite and sulfate together with lithogenic minerals such as SiO2 and aluminosilicate, are eventually uplifted during the interval from spring to autuum. The predominantly fine saline particles uplifted from the SSL are likely transported eastward by the winter monsoon circulation and westerlies. Recent degradation of saline lands in Northeastern China would not only increase the frequency of dust storm events in the downwind area, but also might change the chemical composition of the Asian dust emissions.展开更多
Assuming spheroidal and spherical particle shapes for mineral dust aerosols,the effect of particle shape on dust aerosol optical depth retrievals,and subsequently on instantaneous shortwave direct radiative forcing（S...Assuming spheroidal and spherical particle shapes for mineral dust aerosols,the effect of particle shape on dust aerosol optical depth retrievals,and subsequently on instantaneous shortwave direct radiative forcing（SWDRF） at the top of the atmosphere（TOA）,is assessed based on Moderate Resolution Imaging Spectroradiometer（MODIS） data for a case study.Specifically,a simplified aerosol retrieval algorithm based on the principle of the Deep Blue aerosol retrieval method is employed to retrieve dust aerosol optical depths,and the Fu–Liou radiative transfer model is used to derive the instantaneous SWDRF of dust at the TOA for cloud-free conditions.Without considering the effect of particle shape on dust aerosol optical depth retrievals,the effect of particle shape on the scattering properties of dust aerosols（e.g.,extinction efficiency,single scattering albedo and asymmetry factor） is negligible,which can lead to a relative difference of at most 5% for the SWDRF at the TOA.However,the effect of particle shape on the SWDRF cannot be neglected provided that the effect of particle shape on dust aerosol optical depth retrievals is also taken into account for SWDRF calculations.The corresponding results in an instantaneous case study show that the relative differences of the SWDRF at the TOA between spheroids and spheres depend critically on the scattering angles at which dust aerosol optical depths are retrieved,and can be up to 40% for low dust-loading conditions.展开更多
The paper presents data on the modern state of some important botanical territories of the Ustyurt plateau. Materials on the effect of dust rising from the main highway of the oil and gas sector on the vegetation cove...The paper presents data on the modern state of some important botanical territories of the Ustyurt plateau. Materials on the effect of dust rising from the main highway of the oil and gas sector on the vegetation cover of the adjacent areas studied are considered. The results of the analysis showed that the vitality of dominants and rare species along the road and closer to it is low, the projective coverage does not exceed 8%. Starting from 100 to 200 m, the vitality of the dominants improves. With a distance of 500 m from the roads, the species composition increases, the projective coverage reaches 12%. The evaluation of the vitality of dominant and/or endemic species, the comparison of the projective cover and the species diversity of the pilot site with the control plot, and also the method of weighing the annual shoots of dominant and/or rare species with all vegetative and generative elements in a comparative aspect give reliable results in determining the degree Anthropogenic impact on the vegetation cover of Ustyurt. Inclusion of dominants the restoration of vegetation by phytoremediation of the study area gives promising results.展开更多
Fibrous-type flters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods.Dust cleansing devices including fooded-bed dust scrubbers use these mesh-type m...Fibrous-type flters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods.Dust cleansing devices including fooded-bed dust scrubbers use these mesh-type multi-layered flters.These flters trap dust particles efciently on their surface and inside their mesh.However,their continued operation leads to dust build-up and clogging.This results in increased resistance of the flter and lowered airfow rate through the scrubber.This could potentially enhance the exposure of the miners.A non-clogging self-cleaning impingement screen type dust flter was designed by the authors for use in mining and industrial dust cleansing applications.The flter guides dirt-laden air through rapidly turning paths which forces it to shed heavier particles.The particles impact one of the impermeable solid metallic flter surfaces and are removed from the airstream.A full cone water spray installed upstream prevents any surface buildup of dust.This paper summaried the computer models generated to show the flter operations and laboratory experiments including optical particle counting to establish the cleaning efciency.展开更多
文摘This paper presents a method of measuring the particle mean size and dust concentration by small angle near forward light scattering optics and the extinction theory. Its theory is based on Fraunhofer diffraction theory which is the approximation of Mie scattering within the forward Fraunhofer diffraction lobe, and Rosin Rammler function is introduced to describe the particle size distribution in two phase flow in advance. Compared with the values by the sample weight method, the measurement results have a reasonable agreement. The present work has demonstrated that this method will be probably used to monitor the parameters of two phase flow.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Grant Nos.2014GB107000 and 2013GB112008)the National Natural Science Foundation of China(Grant Nos.11320101005,11175060,11375054,and 11075046)the China-Korean Joint Foundation(Grant No.2012DFG02230)
文摘The investigation of dust particle characteristics in fusion devices has become more and more imperative.In the HL-2A tokamak,the morphologies and compositions of dust particles are analyzed by using scanning electron microscopy（SEM） and energy dispersive x-ray spectroscopy（EDX） with mapping.The results indicate that the sizes of dust particles are in a range from 1 μm to 1 mm.Surprisingly,stainless steel spheres with a diameter of 2.5μm-30 μm are obtained.The production mechanisms of dust particles include flaking,disintegration,agglomeration,and arcing.In addition,dynamic characteristics of the flaking dust particles are observed by a CMOS fast framing camera and simulated by a computer program.Both of the results display that the ion friction force is dominant in the toroidal direction,while the centrifugal force is crucial in the radial direction.Therefore,the visible dust particles are accelerated toriodally by the ion friction force and migrated radially by the centrifugal force.The averaged velocity of the grain is on the order of^100 m/s.These results provide an additional supplement for one of critical plasma-wall interaction（PWI） issues in the framework of the International Thermonuclear Experimental Reactor（ITER） programme.
文摘The effect of dust particles on electric contacts and a hazardous size range of hard dust particles using a rigid model were discussed before. As further research, elastic-plastic model of finite element analysis was established in this work, which is closer to real condition. In this work, the behavior of large size and small size particles, and the influence of particles hardness were investigated. The calculating result of small-size particles presents a general hazardous size coefficient for different contact surface morphology; for large-size particles, it presents a hazardous size coefficient for complicated composition of the dust. And the effect of the dust shape is also discussed.
基金European Commission Research Fund for Coal and Steel(Grant Agreement Number–754205)Generalitat de Catalunya(SGR41).Centre of Excellence Severo Ochoa—Spanish Ministry of Science and Innovation(Project CEX2018-000794-S).
文摘Despite international efforts to limit worker exposure to coal dust,it continues to impact the health of thousands of miners across Europe.Airborne coal dust has been studied to improve risk models and its control to protect workers.Particle size distribution analyses shows that using spraying systems to suppress airborne dusts can reduce particulate matter concentrations and that coals with higher ash yields produce finer dust.There are marked chemical differences between parent coals and relatively coarse deposited dusts(up to _(500)μm,DD_(500)).Enrichments in Ca,K,Ba,Se,Pb,Cr,Mo,Ni and especially As,Sn,Cu,Zn and Sb in the finest respirable dust fractions could originate from:(i)mechanical machinery wear;(ii)variations in coal mineralogy;(iii)coal fly ash used in shotcrete,and carbonates used to reduce the risk of explosions.Unusual enrichments in Ca in mine dusts are attributed to the use of such concrete,and elevated K to raised levels of phyllosilicate mineral matter.Sulphur concentrations are higher in the parent coal than in the DD_(500),probably due to relatively lower levels of organic matter.Mass concentrations of all elements observed in this study remained below occupational exposure limits.
基金supported by the National Natural Science Foundation of China(Grant Nos.12064034 and 11562017)the Leading Talents Program of Science and Technology Innovation in Ningxia Hui Autonomous Region,China(Grant No.2020GKLRLX08)+1 种基金the CAS Light of West China Program(Grant No.XAB2017AW03)the Key Research and Development Program of Ningxia Hui Autonomous Region,China(Grant No.2018BFH03004).
文摘Charged photovoltaic glass produces an electrostatic field.The electrostatic field exerts an electrostatic force on dust particles,thus making more dust particles deposited on the glass.In this paper,the contact electrification between the deposited dust particles and the photovoltaic glass is studied.Meanwhile,the surface charge density model of the photovoltaic glass and the electrostatic force of charged particles are analyzed.The results show that with the increasing of the particle impact speed and the inclination angle of the photovoltaic panel,the charges on particles increase to different degrees.Under a given condition,the electrostatic forces acting on the charged particles at different positions above the glass plate form a bell-shaped distribution at a macro level,and present a maximum value in the center of the plate.As the distance between the particle and the charged glass decreases,the electrostatic force exerted on the particle increases significantly and fluctuates greatly.However,its mean value is still higher than the force caused by gravity and the adhesion force,reported by some studies.Therefore,we suggest that photovoltaic glass panels used in the severe wind-sand environment should be made of an anti-static transparent material,which can lessen the dust particles accumulated on the panels.
文摘This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densities,and identified the levels and sources of heavy metal contamination.The concentrations of Zn,Cu,Pb,Sb,and Cd except Mn in airborne particles,road dusts and soils were all in direct proportion to traffic volume.Cd concentrations were low compared with other metals.For instance,the concentrations of Zn,Cu,Pb,Sb,Mn and Cd were 6.6,0.7,2.2,0.1,0.1 and 0.1μg·m-3in PM10along the Changjiu Expressway,792.8,241.4,248.3,9.6,340.5and 8.0 mg·kg-1in road dusts,and 201.1,143.2,59.5,9.5,338.9 and 2.3 mg·kg-1in soils,respectively,but in the case of the ratio of concentration to the environmental background value,most serious contamination was caused by Cd.The sources of the heavy metals were judged by comparisons of the chemical forms of the heavy metals in different environmental media.Pb and Mn in airborne particles were both derived from traffic;Pb in road dusts and soils resulted mainly from the use of leaded gasoline in the past;and Mn in road dusts and soils was derived from parent rocks.Zn,Cu,Sb and Cd in airborne particles,road dusts and soils were derived primarily from traffic,and differences in chemical forms of the heavy metals in different media were due to the interaction between heavy metals in airborne particles and organic matter and other surfaces in road dusts and soils.We also discussed the change of chemical forms of heavy metals in particles of different sizes and under different weather conditions.Bioavailability of heavy metals in airborne particles was much higher than that in road dusts and soils,especially Pb(0.676 in airborne particles,0.159 in road dusts and 0.095 in soils).
基金supported by the Natural Science Foundation of Hebei Province(Nos.B2022407001 and D2021501004)the National Natural Science Foundation of China(No.42075107)the Fundamental Research Funds for the Central Universities(No.N2223011).
文摘An intense Asian dust storm invadedQinhuangdao,a coastal city ofNorth China on April 11-14,2023.We analyzed the bulk water-soluble inorganic ions(WSII)of PM_(10)and PM_(2.5)using an Ion Chromatograph and investigated individual particlemorphology and elemental composition using a scanning electron microscope coupled with energy dispersive X-ray.The results showed when the dust was directly transported to the sampling site from northwestern China(direct transport stages),the PM_(10)mass concentrations were high(675.0μg/m^(3))but the relative humidity(RH)was low.Total WSII were 19.54μg/m^(3)and 11.17μg/m^(3),accounting for 2.90%and 7.25%of the PM_(10)and PM_(2.5),respectively.In addition,the proportion of S-containing individual mineral dust was low(28.7%-35.3%).The results suggested there were limited secondary inorganic aerosol formation.However,when the dust was transported back to the sampling site across the Bohai Sea in the following days(reverse transport stages),both the PM_(10)mass concentrations(462.3μg/m^(3))and RH were high.Total WSII were 43.75μg/m^(3)and 18.71μg/m^(3),accounting for 9.62%and 14.45%of the total PM_(10)and PM_(2.5),respectively.The proportion of S-containing particles was 51.5%-72.5%.In addition,the concentration of NO_(3)^(−)was much higher than that of SO_(4)^(2−).The results suggested both the sulfate and nitrate formation occurred on coarse mineral dust but the nitrate formation exceeded sulfate formation.Interestingly,mostmineral dust,including Sirich particles contained Cl when they passed through the marine atmosphere.The results highlighted the heterogeneous reactions of dust varied in different transport stages.
文摘Stationary electrostatic-potential formation in plasma with immovable dustparticles was investigated by using one-dimensional kinetic analysis. It is clarified that thedensity of negatively charged dust particles below the threshold value makes the potential decreasemonoton-ically. When the dust densities are above the threshold, there appears the stationaryoscillation in an electrostatic potential due to the streaming plasma. It is found that thewavelength of this mode is of the order of Debye length. These phenomena are different from those ofthe conventional dust ion-acoustic waves in plasma, where the effect of dust-charging is not takeninto account.
文摘A large number of cosmic dust particles, micrometeorites and volcanic dust bands have been found and collected in Antarctic ice, snow and glacial sediments, especially in meteorite concentrated regions. Extraterrestrial spherules also have been discovered from the stratosphere and deep-sea sediments. On the basis of their distributive characteristics the cosmic dust particles are classified into interplanetary dust particles and interstellar dust particles. According to their origins cosmic dust particles can be divided into cometary origin particles, asteroidal origin particles, ablation particles from meteorites and interstellar origin particles. The criteria for identifying cosmic dust particles have been established and the origins of cosmic dust particles are also discussed in aegis paper.
文摘The seasonal transport of the Saharan dust to the West African region, near the Gulf of Guinea, during northem winter has been studied over 12 years. Using an optical particle counter, the dust aerosols in the diameter range 0.5-25 μm have been sampled at Kumasi （6040＇ N, l°34＇ W） in Ghana during the winter months of January-February from 1997 to 2009. The settling atmospheric dust particles observed during the peak Harmattan and the background Harmattan periods are analysed for the mean particle size, number and mass concentrations as well as the particle size-frequency. It is shown that the average daily particle diameter, number and mass concentrations obtained in the peak Harmattan periods are 1.57 ± 0.54 μm, 50 ± 25 particles/cm3 and 1,130 ± 994 μg/m3, respectively, while for the background Harmattan these values are correspondingly, 1.31 ±0.31 μm, 32 ±12 particles/cm3 and 576 ±429 μg/m3, respectively. These experimental results will be useful for the design of ambient air-filters and for understanding the West African climate change.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12075315 and 11675261)。
文摘The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characterized by particle distribution, nearest neighbor configuration and pair correlation function. The current autocorrelation function, the dispersion relation and sound speed are used to represent the wave properties. The wave propagation of the dust lattice closely relates to the lattice structure. It shows that the number of defect particles can affect the dust lattice local structure and then affect the dispersion relations of waves propagating in it. The presence of defect particles has a greater effect on the transverse waves than on the longitudinal waves of the dust lattice. The appropriate number of defect particles can weaken the anisotropy property of the lattice.
基金Project supported by the National Natural Science Foundation of China(Grant No.11475223)the National Magnetic Confinement Fusion Science Program of China(Grant No.2015GB101003)the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics(Grant Nos.11261140328 and2012K2A2A6000443)
文摘The structure of the sheath in the presence of energetic particles is investigated in the multi-fluid framework. Based on the orbital motion limited（OML） theory, the dust grain charging inside the sheath of plasma containing energetic particles is examined for the carbon wall, and then the effect of the energetic particles on the stationary dust particle inside the sheath is discussed through the trapping potential energy. It is found that with the increase of energetic ion concentration or energy,the size of dust staying in levitation equilibrium decreases and the levitating position is much closer to the wall. In the case of deuterium ions as energetic ions, the bigger dust particle can be trapped by the sheath than in the case of hydrogen ions as energetic ions. When the energetic electron component is present, the levitating position of dust particle in the sheath depends strongly on the energetic electron. The levitating dust particle is closer to the wall as the energetic electron energy or concentration is increased. In addition, with the increase of temperature of thermal background ion, the size of dust particle trapped by the sheath decreases and the levitating positions of dust particles with the same size radius inside the sheath move toward the wall. Our results can be helpful in investigating the property of the sheath where the energetic particle component is present.
文摘Fine particulates instead of others create particulate pollution and they are easier to escape from almost all conventional collectors of low- or medium-efficiency. It is of practical significance to take full advantages of particle coagulation by electrostatic forces to upgrade the collertors' performance. This paper investigates the main mechanisms of coagulation, all possible electrostatic forces existing in the collectors and their effects on the particle coagulation. To make particle kinetic coagulation electrostatically enhanced be a step of the conventional collectors. operations,certain conditions should be created through some medifications of the collectors. Based on that ,the authors suggest that a precharger electro-cyclone technique be applied to improve the performance of common cyclones still widely used in many places. And a preliminary semi-industrial test has been carried out at Jiawang Power Station, Xuzhou, Jiangsu Province, and the results show that the modified cyclone increases its efficiency from about 80% to 92~94%.
基金financially supported by the National Key Research and Development Program of China(No.SQ2017YFSF060069)the National Natural Science Foundation of China(No.51574017)
文摘The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The results show that the HBD particles can be classified into three types based on their particle size(PS):larger particles(PS>10μm),medium particles(1μm≤PS≤10μm),and nanoparticles(PS<1μm).The cumulative volume of respirable dust(PS≤10μm)was 84.45%.In addition,three shapes of HBD were observed by SEM:prism,flake,and bulk.In particular,the small particles were mostly flaky,with a greater possibility of being inhaled.Furthermore,the body and surface chemical compounds of HBD were determined by XRD and XPS,respectively.Ammonium adipate(C6H16N2O4)was the only organic compound in the body of HBD,but its mass fraction was only 13.4%.However,the content of organic C on the surface of HBD was 85.35%.This study demonstrated that the small-particle size and large amount of organic matter on the surface of HBD are the main reasons for its hydrophobicity,which can provide important guidance for controlling respirable dust in iron mines.
基金supported by the Key Project of Zhe-jiang Province (No. 2006C13057)the CAS Program(No. KZCX1-YW-06-02)the Jiaxing City Project(No. 2005AZ3040).
文摘Particles of dust washed off streets by stormwater are an important pathway of polyaromatic hydrocarbons （PAHs） into urban streams. This article presented a comprehensive assessment of the size distribution of PAHs in street dust particles, the potential risks of the particles in urban streams, and the sources and sinks of PAHs in the stream network. This assessment was based on measurements of 16 PAHs from the USEPA priority list in street dust particles and river sediments in Xincheng, China. The content of total PAHs ranged from 1629 to 8986 Dg/kg in street dust particles, where smaller particles have a higher concentrations. Approximately 55% of the total PAHs were associated with particles less than 250 μm which accounted for 40% of the total mass of street dust. The PAH quantities increased from 2.41 to 46.86 μg/m2 in the sequence of new residential, rising through main roads, old town residential, commercial and industrial areas. The sediments in stream reaches in town were found to be sinks for street dust particle PAHs. The research findings suggested that particle size, land use and the hydrological conditions in the stream network were the factors which most influenced the total loads of PAH in the receiving water bodies.
基金supported in a part by Chinese National Key Project of Basic Research (No G2000048703)the Grant-in-Aid for Scientific Research (No 16310008,18403002) from the Ministry of Education, Culture,Sports, Science and Technology, Japan
文摘Recent observations of Asian dust storms show an eastern expansion of the source area to degraded lands, where dust emissions have been little studied. The dust concentrations over the saline land of the western Songnen Plain （SSL）, Northeastern China, are circumstantially higher than those from the northwestern Chinese deserts. These concentrations are sensitive to the surface soil conditions and wind velocity on the ground. The dust samples collected during dust storm events on the SSL contain abundant Na, Mg, A1, K, Ca, Fe and Ti, as well as toxic elements such as Cu, V, Zn and Ba. Individual particle analysis reveals that fine saline particles （〈 10 μm in diameter） on the saline land, consisting largely of carbonate, halite and sulfate together with lithogenic minerals such as SiO2 and aluminosilicate, are eventually uplifted during the interval from spring to autuum. The predominantly fine saline particles uplifted from the SSL are likely transported eastward by the winter monsoon circulation and westerlies. Recent degradation of saline lands in Northeastern China would not only increase the frequency of dust storm events in the downwind area, but also might change the chemical composition of the Asian dust emissions.
基金supported by the National Natural Science Foundation of China(Grant No.41276181)
文摘Assuming spheroidal and spherical particle shapes for mineral dust aerosols,the effect of particle shape on dust aerosol optical depth retrievals,and subsequently on instantaneous shortwave direct radiative forcing（SWDRF） at the top of the atmosphere（TOA）,is assessed based on Moderate Resolution Imaging Spectroradiometer（MODIS） data for a case study.Specifically,a simplified aerosol retrieval algorithm based on the principle of the Deep Blue aerosol retrieval method is employed to retrieve dust aerosol optical depths,and the Fu–Liou radiative transfer model is used to derive the instantaneous SWDRF of dust at the TOA for cloud-free conditions.Without considering the effect of particle shape on dust aerosol optical depth retrievals,the effect of particle shape on the scattering properties of dust aerosols（e.g.,extinction efficiency,single scattering albedo and asymmetry factor） is negligible,which can lead to a relative difference of at most 5% for the SWDRF at the TOA.However,the effect of particle shape on the SWDRF cannot be neglected provided that the effect of particle shape on dust aerosol optical depth retrievals is also taken into account for SWDRF calculations.The corresponding results in an instantaneous case study show that the relative differences of the SWDRF at the TOA between spheroids and spheres depend critically on the scattering angles at which dust aerosol optical depths are retrieved,and can be up to 40% for low dust-loading conditions.
文摘The paper presents data on the modern state of some important botanical territories of the Ustyurt plateau. Materials on the effect of dust rising from the main highway of the oil and gas sector on the vegetation cover of the adjacent areas studied are considered. The results of the analysis showed that the vitality of dominants and rare species along the road and closer to it is low, the projective coverage does not exceed 8%. Starting from 100 to 200 m, the vitality of the dominants improves. With a distance of 500 m from the roads, the species composition increases, the projective coverage reaches 12%. The evaluation of the vitality of dominant and/or endemic species, the comparison of the projective cover and the species diversity of the pilot site with the control plot, and also the method of weighing the annual shoots of dominant and/or rare species with all vegetative and generative elements in a comparative aspect give reliable results in determining the degree Anthropogenic impact on the vegetation cover of Ustyurt. Inclusion of dominants the restoration of vegetation by phytoremediation of the study area gives promising results.
基金Funding The authors acknowledge the National Institute for Occupational Safety and Health(NIOSH)for funding this research project.
文摘Fibrous-type flters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods.Dust cleansing devices including fooded-bed dust scrubbers use these mesh-type multi-layered flters.These flters trap dust particles efciently on their surface and inside their mesh.However,their continued operation leads to dust build-up and clogging.This results in increased resistance of the flter and lowered airfow rate through the scrubber.This could potentially enhance the exposure of the miners.A non-clogging self-cleaning impingement screen type dust flter was designed by the authors for use in mining and industrial dust cleansing applications.The flter guides dirt-laden air through rapidly turning paths which forces it to shed heavier particles.The particles impact one of the impermeable solid metallic flter surfaces and are removed from the airstream.A full cone water spray installed upstream prevents any surface buildup of dust.This paper summaried the computer models generated to show the flter operations and laboratory experiments including optical particle counting to establish the cleaning efciency.
