Optical Modeling of Sea Salt Aerosols Using in situ Measured Size Distributions and the Impact of Larger Size Particles

Sea salt aerosols play a critical role in regulating the global climate through their interactions with solar radiation.The size distribution of these particles is crucial in determining their bulk optical properties.In this study,we analyzed in situ measured size distributions of sea salt aerosols from four field campaigns and used multi-mode lognormal size distributions to fit the data.We employed super-spheroids and coated super-spheroids to account for the particles’non-sphericity,inhomogeneity,and hysteresis effect during the deliquescence and crystallization processes.To compute the singlescattering properties of sea salt aerosols,we used the state-of-the-art invariant imbedding T-matrix method,which allows us to obtain accurate optical properties for sea salt aerosols with a maximum volume-equivalent diameter of 12μm at a wavelength of 532 nm.Our results demonstrated that the particle models developed in this study were successful in replicating both the measured depolarization and lidar ratios at various relative humidity(RH)levels.Importantly,we observed that large-size particles with diameters larger than 4μm had a substantial impact on the optical properties of sea salt aerosols,which has not been accounted for in previous studies.Specifically,excluding particles with diameters larger than 4μm led to underestimating the scattering and backscattering coefficients by 27%−38%and 43%−60%,respectively,for the ACE-Asia field campaign.Additionally,the depolarization ratios were underestimated by 0.15 within the 50%−70%RH range.These findings emphasize the necessity of considering large particle sizes for optical modeling of sea salt aerosols.

Extended wet sieving method for determination of complete particle size distribution of general soils

The traditional standard wet sieving method uses steel sieves with aperture?0.063 mm and can only determine the particle size distribution(PSD)of gravel and sand in general soil.This paper extends the traditional method and presents an extended wet sieving method.The extended method uses both the steel sieves and the nylon filter cloth sieves.The apertures of the cloth sieves are smaller than 0.063 mm and equal 0.048 mm,0.038 mm,0.014 mm,0.012 mm,0.0063 mm,0.004 mm,0.003 mm,0.002 mm,and 0.001 mm,respectively.The extended method uses five steps to separate the general soil into many material sub-groups of gravel,sand,silt and clay with known particle size ranges.The complete PSD of the general soil is then calculated from the dry masses of the individual material sub-groups.The extended method is demonstrated with a general soil of completely decomposed granite(CDG)in Hong Kong,China.The silt and clay materials with different particle size ranges are further examined,checked and verified using stereomicroscopic observation,physical and chemical property tests.The results further confirm the correctness of the extended wet sieving method.

Particle size spatial distribution in landslide dams

The particle composition and spatial distribution of landslide-induced dam bodies are critical geotechnical parameters for studying the hazards of dam-break floods.However,current research often neglects the influence of the initial particle composition and spatial distribution of the landslide on the particle composition and spatial distribution of the landslide dam.This study investigated the impact of initial particle size distribution,volume,and sliding length on the energy and velocity changes of characteristic particles during the sliding process and the spatial distribution of particle sizes in the landslide dam body.Numerical simulations and physical models were employed to examine the effects of sequential gradient arrangements(where particle sizes decrease from top to bottom)and four other different initial particle arrangements on the energy and velocity changes of particles and the spatial distribution of particle sizes in the dam body.The study reveals the characteristics of translational and rotational energy of different particles and the laws of mechanical energy conversion,obtaining the spatial distribution patterns of particle sizes in landslide-induced dams.The results show that under the sequential gradient arrangement,the energy dissipation of the landslide movement is lower,with larger particles mainly distributed at the distal end and smaller particles at the proximal end of the landslide dam.In contrast,under the reverse gradient arrangement,the energy dissipation of the landslide movement is higher,and the distribution pattern of the dam particles is opposite to that of the sequential gradient arrangement.For the other arrangement modes,the spatial distribution of dam particles falls between the aforementioned two.There is a positive correlation between particle size and translational kinetic energy within the particle flow during the landslide process,and rotational motion increases energy dissipation.Under constant slope conditions,sliding length does not affect the movement pattern of the particle flow or the spatial distribution of particles in the dam body.The findings of this study provide a scientific basis for the accurate simulation and prediction of dam-break flood processes.

Microfluidic preparation of surfactant-free ultrafine DAAF with tunable particle size for insensitive initiator explosives

High purity and ultrafine DAAF(u-DAAF)is an emerging insensitive charge in initiators.Although there are many ways to obtain u-DAAF,developing a preparation method with stable operation,accurate control,good quality consistency,equipment miniaturization,and minimum manpower is an inevitable requirement to adapt to the current social technology development trend.Here reported is the microfluidic preparation of u-DAAF with tunable particle size by a passive swirling microreactor.Under the guidance of recrystallization growth kinetics and mixing behavior of fluids in the swirling microreactor,the key parameters(liquid flow rate,explosive concentration and crystallization temperature)were screened and optimized through screening experiments.Under the condition that no surfactant is added and only experimental parameters are controlled,the particle size of recrystallized DAAF can be adjusted from 98 nm to 785 nm,and the corresponding specific surface area is 8.45 m^(2)·g^(-1)to 1.33 m^(2)·g^(-1).In addition,the preparation method has good batch stability,high yield(90.8%-92.6%)and high purity(99.0%-99.4%),indicating a high practical application potential.Electric explosion derived flyer initiation tests demonstrate that the u-DAAF shows an initiation sensitivity much lower than that of the raw DAAF,and comparable to that of the refined DAAF by conventional spraying crystallization method.This study provides an efficient method to fabricate u-DAAF with narrow particle size distribution and high reproducibility as well as a theoretical reference for fabrication of other ultrafine explosives.

DETERMINATION OF SIZE DISTRIBUTION OF THE CRYSTALLINE PARTICLE IN AGED METALLIC GLASS BY SMALL ANGLE X-RAY SCATTERING

Ⅰ. INTRODUCTIONAlthough many authors have investigated the structure of annealed metallic glass by means of small angle X-ray scattering (SAXS), there has been no report in which size distribution of the crystalline particle in aged metallic glass is determined. Determining size distribution of the crystalline particle will be beneficial to understanding the nucleation and growth process of the crystalline particle. In this note, size distribution of the crystalline parti-

Measuring particle size distribution and total number in the activation chamber of desulfurization system by PIV

Application of particle image velocity (PIV) techniques for measuringparticle size distribution and total number in an activation chamber of desulfurization system isintroduced. Watersheld algorithm is used to choose the suitable initial gray level threshold whichis used to change the gray level images taken by PIV to black and white ones, then every particle inan image is isolated totally. For every isolating particle, its contour is tracked by the edgeenhancement filter function and kept by Freeman s chain code. Based on a set of particle s chincode, its size and size distribution are calculated and sorted. Finally, the experimental data ofcalcium particles and water drops, separately injected into the activation chamber, and the erroranalysis of data are given out.

Preparation of crystalline rare earth carbonates with large particle size from the lixivium of weathered crust elution-deposited rare earth ores

Crystalline rare-earth(RE)carbonates having large particle size were prepared from the lixivium of weathered crust elution-deposited rare-earth ores using the precipitation method with ammonium bicarbonate as the precipitant.Their chemical composition was studied using elemental and thermogravimetric analyses(TGA),and their structure and morphology were characterized using Fourier transform infrared(FTIR)spectroscopy,X-ray diffraction(XRD),and scanning electron microscopy(SEM).The results demonstrate that the crystalline rareearth carbonate is a hydrated basic carbonate or oxycarbonate and not astable intermediate carbonate in the process of thermal decomposition.The particle size of crystalline rare-earth carbonates with large particle size is in the range of 50–200μm.With an RE2O3 content of up to 95wt%,the quality of crystalline rare-earth carbonates is higher compared to the Chinese National Standard(GB/T 28882–2012).The quality of the product is superior to the Chinese National Standard.

Stability of the Dividing Distribution Function Method for ParticleSize Distribution Analysis in Small Angle X－Ray Scattering

The Dividing Distribution Function (DDF) method is one of the methods by which the particle size distribution of ultrafine powder can be evaluated from its small angle X-ray scattering data. In this paper, the stability of the solution obtained from DDF method has been investigated through optimizing the coefficient matrix, introducing a damping factor and a least square treatment. All calculations were accomplished with a microcomputer. It was shown that the average deviations of the size distribution obtained are not larger than the assigned random errors to the scattering intensities as long as the corresponding requirements are satisfied.

Multifractal characteristics and spatial variability of soil particle-size distribution in different land use patterns in a small catchment of the Three Gorges Reservoir Region,China

Characterizing soil particle-size distribution is a key measure towards soil property.The purpose of this study was to evaluate the multifractal characteristics of soil particle-size distribution among different land-use from a purple soil catchment and to generalize the spatial variation trend of multifractal parameters across the catchment.A total of 84 soil samples were collected from four kinds of land use patterns(dry land,orchard,paddy,and forest)in an agricultural catchment in the Three Gorges Reservoir Region,China.The multifractal analysis method was applied to quantitatively characterize the soil particle size distribution.Six soil particle size distribution(PSD)multifractal parameters(D(0),D(1),D(2),(35)a(q),(35)f[a(q)],α(0))were computed.Additionally,a geostatistical analysis was employed to reveal the spatial differentiation and map the spatial distribution of these parameters.Evident multifractal characteristics were found.The trend of generalized dimension spectrum of four land use patterns was basically consistent with the range of 0.8 to 2.0.However,orchard showed the largest monotonic decline,while the forest demonstrated the smallest decrease.D(0)of the four land use patterns were ranked as:dry land<orchard<forest<paddy,the order of D(1)was:dry land<paddy<orchard<forest,D(2)presented a rand-size relationship as dry land<forest<paddy<orchard.Furthermore,all land-use patterns presented asΔf[α(q)]<0.The rand-size relationship ofα(0)was same as D(0).The best-fitting model for D(0),D(1),D(2)andΔf[α(q)]was spherical model,forΔα(q)was gaussian model,and forα(0)was exponential model with structure variance ratio was 1.03%,49.83%,0.84%,1.48%,22.20%and 10.60%,respectively.The results showed that soil particles of each land use pattern were distributed unevenly.The multifractal parameters under different land use have significant differences,except forΔα(q).Differences in the composition of soil particles lead to differences in the multifractal properties even though they belong to the same soil texture.Farming behavior may refine particles and enhance the heterogeneity of soil particle distribution.Our results provide an effective reference for quantifying the impact of human activities on soil system in the Three Gorges Reservoir region.

Particle Size Distribution,Powder Agglomerates and Their Effects on Sinterability of Ultrafine Alumina Powders

An intensive study of the particle size distribution of four commercial ultrafine alumina powders to obtain information about the powder agglomeration and relate them to the compactibility and the sinterability has been made.

Study by Inverse Method the Size Distribution of the Particle of Carbonaceous Generated in RF Discharge

One of the difficulties encountered in the study of dusty plasmas is related to the knowledge of the size of the dust particles present. A variety of sources, physical and chemical mechanisms of formation, causes a wide variety of sizes and morphologies of dust. The diameter of a dust will not be unique but spread over several orders of magnitude. Its distribution in number, surface, mass or volume is called distribution. It is important to know this distribution in particle size because it strongly impacts the physical and radiative processes. To have a dust distribution in situ is very difficult;the reverse method can identify the particle populations from light extinction measures. In this study, we present an inversion procedure with a Tikhonov regularization dedicated to the determination of volume size distribution (V-PSD) from extinction measurements corresponding to the different wavelengths obtained by the Extinction Spectrometry technique.

Effect of nano-particle size on product distribution and kinetic parameters of Fe/Cu/La catalyst in Fischer-Tropsch synthesis

Effects of nano-particle size on hydrocarbon production rates and distributions for precipitated Fe/Cu/La catalysts in Fischer-Tropsch synthesis were investigated.Nano-structured iron catalyst was prepared by micro-emulsion method.The concept of two superimposed AndersonSchulz-Flory （ASF） distributions has been applied for the representation of the effects of reaction conditions and nano-particles size on kinetics parameters and product distributions.These results reveal that by reducing the particle size of catalyst,the break in ASF distributions was decreased.Also useful different kinetics equations for synthesis of C3 to C9 and C10 to C22 were determined by using α1 and α2 chain growth probabilities.

MEASUREMENTS OF PARTICLE NUMBER SIZE DISTRIBUTIONS AND NEW PARTICLE FORMATION EVENTS DURING WINTER IN THE PEARL RIVER DELTA REGION,CHINA

Particle number size distribution(PNSD) between 10 nm and 20 μm were measured in the Pearl River Delta(PRD) region in winter 2011.The average particle number concentration of the nucleation mode(10-20 nm),Aitken mode(20-100 nm),accumulation mode(100 nm-1μm) and coarse mode(1-20 μm) particles were 1 552,7 470,4 012,and 19 cm-3,respectively.The volume concentration of accumulation mode particles with peak at 300 nm accounted for over 70% of the total volume concentration.Diurnal variations and dependencies on meteorological parameters of PNSD were investigated.The diurnal variation of nucleation mode particles was mainly influenced by new particle formation events,while the diurnal variation of Aitken mode particles correlated to the traffic emission and the growth process of nucleation mode particles.When the PRD region was controlled by a cold high pressure,conditions of low relative humidity,high wind speed and strong radiation are favorable for the occurrence of new particle formation(NPF) events.The frequency of occurrence of NPF events was 21.3% during the whole measurement period.Parameters describing NPF events,including growth rate(GR) and source rate of condensable vapor(Q),were slightly larger than those in previous literature.This suggests that intense photochemical and biological activities may be the source of condensable vapor for particle growth,even during winter in the PRD.

Particle Size Distributions and Organic-Inorganic Compositions of Suspended Particulate Matters Around the Bohai Strait

Laser in situ scattering and transmissometry(LISST) significantly improves our ability to assess particle size distribu-tion(PSD) in seawater, while wide-ranging measurements of the organic-inorganic compositions of suspended particulate matters(SPM) are still difficult by using traditional methods such as microscopy. In this study, PSD properties and SPM compositions around the Bohai Strait(China) were investigated based on the measurements by LISST in combination with hydro-biological parameters collected from a field survey in summer 2014. Four typical PSD shapes were found in the region, namely right-peak, left-peak, dou-ble-peak and negative-skew shapes. The double-peak and negative-skew shapes may interconvert into each other along with strong hydrodynamic variation. In the upper layer of the Bohai Sea, organic particles were in the majority, with inorganic particles rarely observed. In the bottom layer, SPM were the mixture of organic and inorganic matters. LISST provided valuable baseline information on size-resolved organic-inorganic compositions of SPM: the size of organic particles mainly ranged from 4 to 20 μm and 40 to 100 μm, while most SPM ranging from 20 to 40 μm were composed of inorganic sediment.

Sampling Surface Particle Size Distributions and Stability Analysis of Deep Channel in the Pearl River Estuary

Particle size distributions （PSDs） of bottom sediments in a coastal zone are generally multimodal due to the complexity of the dynamic environment. In this paper, bottom sediments along the deep channel of the Pearl River Estuary （PRE） are used to understand the multimodal PSDs＇ characteristics and the corresponding depositional environment. The results of curve-fitting analysis indicate that the near-bottom sediments in the deep channel generally have a bimodal distribution with a fine component and a relatively coarse component. The particle size distribution of bimodal sediment samples can be expressed as the sum of two lognormal functions and the parameters for each component can be determined. At each station of the PRE, the fine component makes up less volume of the sediments and is relatively poorly sorted. The relatively coarse component, which is the major component of the sediments, is even more poorly sorted. The interrelations between the dynamics and particle size of the bottom sediment in the deep channel of the PRE have also been investigated by the field measurement and simulated data. The critical shear velocity and the shear velocity are calculated to study the stability of the deep channel. The results indicate that the critical shear velocity has a similar distribution over large part of the deep channel due to the similar particle size distribution of sediments. Based on a comparison between the critical shear velocities derived from sedimentary parameters and the shear velocities obtained by tidal currents, it is likely that the depositional area is mainly distributed in the northern part of the channel, while the southern part of the deep channel has to face higher erosion risk.

Particle Size Distribution of Kaolinite and Halloysite in Weathering Products of Granite and Its Implications for Pedogenesis

The kaolins collected from a profile of weathered granite at Yichun County, Jiangxi Province have been subjected to particle size fractionation by the conventional sedimentation method and examined by XRD,SEM and TEM. All of them exhibit a mixture phase of poorly crystallized kaolinites and halloysites (0.7 nm) occurring as the main clay minerals. Electron micrographs reveal that plate kaolinites are the principal constitution in the coarse fraction, and more tubular and curled halloysite (0.7 nm) in the fine fraction. Both of them show normal probability curves in particle size distributions. The ratios of kaolinite and halloysite (0.7 nm) in different size fractions are examined by X-ray diffraction with a series of X-ray patterns characterized by three main peaks at d(001), d(002) and d(020),varying in intensity. Therefore, an index Qhm, expressed as (Id(001) + Id(002))/(2×Id(020)), is designed to indicate relative ratios of the two clay minerals in a number of mixture phases. Because kaolinite and halloysite (0.7nm) commonly occurred, respectively, in low and medium leaching microenvironment, the index Qhm can be used to indicate weathering and pedogenic.conditions of a weathering crust.

Analysis on the Distribution Characteristics of Atmospheric Aerosol Particles in Hebei Area in the Cloudy Day Condition

By using the probe data of two sorties airplane in the middle and southern parts of Hebei Province in 2007 spring,the characteristics of atmospheric aerosol particles concentration and size distribution in the area in the cloudy day situation were analyzed.The results showed that the overall trend of aerosol particles concentration in the weather systems which included the south branch trough and North China low vortex was the decrease as the height increased.However,if the cirrostratus was in the high altitude,it increased as the height increased.In the bottom of inversion layer,there existed the obvious accumulation of aerosol and cloud droplet.Affected by the complex weather systems,the aerosol particle size distribution presented the multi-peak type for the disturbance of updraft or turbulence.

Simulating the particle size distribution of rockfill materials based on its statistical regularity

The particle size distribution of rockfill is studied by using granular mechanics, mesomechanics and probability statistics to reveal the relationship of the distribution of particle size to that of the potential energy intensity before fragmentation, which finds out that the potential energy density has a linear relation to the logarithm of particle size and deduces that the distribution of the logarithm of particle size conforms to normal distribution because the distribution of the potential energy density does so. Based on this finding and by including the energy principle of rock fragmentation, the logarithm distribution model of particle size is formulated, which uncovers the natural characteristics of particle sizes on statistical distribution. Exploring the properties of the average value, the expectation, and the unbiased variance of particle size indicates that the expectation does notequal to the average value, but increases with increasing particle size and its ununiformity, and is always larger than the average value, and the unbiased variance increases as the ununiformity and geometric average value increase. A case study proves that the simulated results by the proposed logarithm distribution model accord with the actual data. It is concluded that the logarithm distribution model and Kuz-Ram model can be used to forecast the particle-size distribution of inartificial rockfill while for blasted rockfill, Kuz-Ram model is an option, and in combined application of the two models, it is necessary to do field tests to adjust some parameters of the model.

Experimental study for the particle size distribution of mine spoil pile cross section

The aim of the experiment is to analyze and view the distribution of gangue withdifferent particle sizes in mine spoil pile cross section.According to the Dimensionalmethod,'Pi'theorem was employed first to abbreviate ten physical and mechanical parametersto three dimensionless groups, and then the similarity criterion and coefficient ofthe experiment were determined and calculated based on particle size distribution curve.The similarity model was designed and constructed to represent the process of the minespoil pile.The profile of the final model shows that the small sized particles mainly composethe upper zone of the mine spoil pile, while the bottom of the pile is dominated bybigger sized particles, and the intermediate section presents a zigzag stripe cross-beddingstructure which is composed by small-medium scale particles and medium-large scaleparticles.Each stripe has two critical angles: one is the angle in which gangue particlescan maintain their stability condition, with approximate range from 24° to 26°; and theother is the angle in which particles can stop gliding downwards, approximately varyingfrom 34° to 36°.

Particle size distribution of the organic matters in the treated leachate using aged-refuse-bioreactor

Micro-filtration membrane （1.2 μm）, hyper-filtration membrane （0.45 μm） and nano-filtration membrane （1000 Dalton） were used to characterize the particle size distribution of the organic matters in effluent leachate treated by the aged-refuse-bioreactor（ARB） installed at Laogang Refuse Landfill, Shanghai. The results showed that the particle size distribution of the treated fresh and aged leachate using the ARB were quite consistent. The organic matter with particle size below 1000 Dalton accounted for about 90%, balanced with the suspended （〉1.2 μm） and colloidal （1000 Dalton-l.2μm） matters. Hence, it is proposed that coagulation, nano-filtration and electrically chemical oxidation may be not applicable for the advanced treatment for the effluents to reach the discharge standard limit value defined in Chinese national Standard for Pollution Control on the Landfill Site of Municipal Solid Wastes （GB16889-2008）, CODCr〈100 mg/L. Aged refuse bioreactor combined reverse osmosis was suggested as an economically and technically feasible technology to treat sanitary landfill leachate.