Estimation of particle size distribution from cross-sectional particle diameter on the cutting plane

To control highly functional sintered materials, it is necessary to evaluate particle size segregation within materials. In the present study, a new method for estimating particle size distribution is proposed; this method considers the occurrence probability of the cutting diameter. The proper particle size distribution in a particle bed was estimated by calculating a matrix consisting of the occurrence probability and the distribution of particle diameters measured on a cutting plane. The estimated particle size distribution was smoothed using the Phillips–Twomey method. A cavity-filling simulation was carried out to verify the validity of the proposed method using the Distinct Element Method. The particle size distribution estimated by this method correlated well with the actual particle size distribution. The effect of particle size distributions with various geometrical standard deviations on the accuracy of estimated values was also investigated. The accuracy increased as the geometric standard deviation increased, and there was an optimum particle size bin number for a specific particle distribution. It was found that a large bin number and a large number of measured particles were required to obtain a higher accuracy for narrow size distributions.     

EARLY-STAGE EVOLUTION OF PARTICLE SIZE DISTRIBUTION DUE TO GRAVITATIONAL COAGULATION

Evolution of the particle size distribution of an aerosol undergoing gravitational coagulation in early time stages was numerically investigated. The moment method was also applied in initiating a simple approach to the changes of particle size distribution parameters. Finally, an analytical solution was developed approximating the collision kernel into a form suitable for the analysis. The results underwent analysis by comparison. The derived analytical solution was found to be in good agreement with the numerical moment method. However, the results of the moment method do not exactly coincide with the results of the direct numerical integration because the particle size distribution does not attain the log-normal size distribution form.     

EARLY-STAGE EVOLUTION OF PARTICLE SIZE DISTRIBUTION DUE TO GRAVITATIONAL COAGULATION

ABSTRACT

Evolution of the particle size distribution of an aerosol undergoing gravitational coagulation in early time stages was numerically investigated. The moment method was also applied in initiating a simple approach to the changes of particle size distribution parameters. Finally, an analytical solution was developed approximating the collision kernel into a form suitable for the analysis. The results underwent analysis by comparison. The derived analytical solution was found to be in good agreement with the numerical moment method. However, the results of the moment method do not exactly coincide with the results of the direct numerical integration because the particle size distribution does not attain the log-normal size distribution form.     

水泥粉体粒度分布分维与其流动性的关系研究

为研究水泥粉体粒度分布分维与流动性的相关性,本文中将粒度分布分维作为表征水泥粉体的粒度分布特征,用图像分析法测算了5种水泥颗粒样品的粒度分布分维,5种水泥样品粒度分布分维值处于2.1006～2.2931之间;并用卡尔指数法测量了水泥样品的流动系数,考察了水泥粉体粒度分布分维及其与粉体流动性的关系,研究表明:水泥粉体粒度分布分维与其流动性呈线性负相关性。     

Application of dynamic light scattering to the study of small marine particles

Small particles ranging from approximately 0.1 μm to several micrometers in size, which include detrital material, bacteria, and other planktonic microorganisms, make a significant contribution to light scattering in the upper ocean. The scattering properties of these particles are strongly dependent on their size, which is difficult to measure in the submicrometer range with commonly used electronic resistive counters and microscopic techniques. We examined the size of small marine particles by application of the dynamic light scattering (DLS) method. In this method the time-dependent autocorrelation function of scattered intensity by particles undergoing Brownian motion provides information about the size of particles. The samples were collected in clear oceanic waters off the coast of Southern California. The mean hydrodynamic diameter of particles, determined from the DLS measurements at a scattering angle of 45°, was 0.54μ m. This indicates that the major contribution to scattering at this angle comes rom submicrometer particles. We also described an inverse method for estimating the general slope of the size distribution of small marine particles from the mean hydrodynamic diameter. This method is based on calculations of the size distribution weighted by distribution from Mie theory and assumes that a power-law approximation represents the actual particle scattered intensity. These calculations suggested that particulate assemblage in our seawater samples was best characterized by a differential size distribution with a slope of -4.35. This estimation was supported by independent measurements of particle size distribution and the spectral beam attenuation coefficient taken from the same samples as those used for the DLS measurements. We also demonstrated that multiangle DLS measurements may be used to determine the representative value of the refractive index of particles.     

Effect of Granulating Method on Particle Size Distribution of Granules and Disintegrated Tablets. I

The average particle size and distribution of granules were found to be dependent on the granulating method. The slugging method produced the widest particle size distribution and the largest average particle size, while the microgranulating method produced the narrowest distribution and the smallest average particle size. The average particle size of dexamethasone granules produced by wet granulating, microgranulating and slugging methods, were reduced on compaction by fragmentation. Of the three, the granules prepared by the slugging method, exhibited maximal average size reduction on compaction. On the other hand, the average particle size of sulfadiazine microgranulates and sulfadiazine slugs were enlarged by consolidation during compaction.     

Prospective Validation of High-Shear Wet Granulation Process by Wet Granule Sieving Method. I. Selection and Characterization of Sieving Parameters for Wet Granules

To characterize the progression of high-shear wet granulation for various drugs and formulations based on the particle size distribution of wet granules during granulation, a general sieving method for wet granules was investigated. Wet granulation was conducted in a 25-liter high-shear mixer using four model drugs with different solubilities and particle sizes (ethenzamide, unmilled and milled acetaminophen, and antipyrine). Because of its small size and efficient sifting mechanism, a sonic sifter was used to determine the wet granulation particle size distribution. From the good correlation of particle size distribution between wet granules and dry-sized granules, an intensity of 80% of full-scale amplitude and a sieving time of 3 min were selected as wet granule sieving parameters. 7% general sieving method showed good measurement precision as long as the determination was completed within 20 min after sampling, Further, the method was independent of sampling position within the mixer chamber.     

Formulation optimization for thermoplastic sizing polyetherimide dispersion by quantitative structure–property relationship: experiments and artificial neural networks

The main function of a sizing in a composite is to fill interface between fibre and polymer matrix. This coating process contributes to increase adhesion between fibre and matrix, and therefore improve mechanical properties of the composites. The aim of this study was to optimize sizing formulations by identifying the experimental parameters influencing the particle size, distribution size and stability of various aqueous emulsions, used in the coating process of carbon fibres with polyetherimide as thermoplastic sizing polymer. A quantitative structure–property relationship (QSPR) method with artificial neural networks was used to determine the main parameters involved in the different formulation steps. The results indicated three recurrent parameters: stirring speed, surfactant concentration and type of reactor which control the particle size, stability and distribution size of the dispersions. With a reduced dataset constituted of 36 entries, this QSPR method was able to predict the stability of the aqueous dispersion of polymer and the particle size with an accuracy of 200 nm for an average diameter ranging from 330 to 2700 nm. The distribution size could be predicted with an accuracy of 0.047 for an experimental size distribution of 0.2.     

高固含量乳液(St/BA/AA)的合成、乳胶粒径及其分布

采用滴加预乳化液的半连续乳液聚合方法,合成了固含量高达65%的苯乙烯/丙烯酸丁酯/丙烯酸(St/BA/AA)共聚物乳液,并系统研究了乳化剂含量、固含量、单体配比、功能单体浓度对乳胶粒大小及分布的影响,利用透射电子显微镜对乳胶粒子的微观形态进行了表征.结果表明,乳化剂及功能单体浓度增加,乳胶粒粒径减小,分布变窄;增加固含量、单体BA用量,乳胶粒径增大,分布加宽.高固含量(St/BA/AA)乳液的平均粒径在150 nm～500 nm范围内,粒径分散系数为1.06～2.5,乳胶粒子呈多分散分布.     

Size distribution measurement of floating particles in the Allen region by a buoyancy weighing-bar method

The particle size distributions of spherical or cylindrical solid particles in the Allen region were measured using a buoyancy weighing-bar method. The particle size distribution obtained in the buoyancy weighing-bar method agrees with those measured by a laser diffraction/scattering method and a sieving method. The present study demonstrates that a buoyancy weighing-bar method is suitable for measuring the particle size distribution of a floating solid in the Allen region.     

Effect of Granulating Method on Particle Size Distribution of Granules and Disintegrated Tablets. I

Abstract

The average particle size and distribution of granules were found to be dependent on the granulating method. The slugging method produced the widest particle size distribution and the largest average particle size, while the microgranulating method produced the narrowest distribution and the smallest average particle size. The average particle size of dexamethasone granules produced by wet granulating, microgranulating and slugging methods, were reduced on compaction by fragmentation. Of the three, the granules prepared by the slugging method, exhibited maximal average size reduction on compaction. On the other hand, the average particle size of sulfadiazine microgranulates and sulfadiazine slugs were enlarged by consolidation during compaction.     

Alternative approach for defining the particle population requirements for static image analysis based particle characterization methods

For image based particle characterisation approaches one of the most common discussion points is determining the number of particles required to have statistical confidence that the measurement is able to adequately describe the distribution of the sample. This topic becomes significantly more challenging when applied to the extraction of single component size distributions from multi-component samples.The aim of this work was to propose a means to accurately assess the particle number requirements using a method specific approach. The method applies a sub-sampling method to the original imaged dataset in order to provide an understanding of the impact of sub-sampling on the ability to accurately reproduce the original distribution.The method was applied to understand the particle number requirements for two batches of theophylline anhydrous with varied particle size distributions, using the input size distribution to guide the requirements for the subsequent multi-component samples of both materials.The results demonstrate the utility of the method to determine the appropriate number of particles required to recreate the size distributions. Whilst the minimum number of particles required to be sampled can be estimated, how those particles are sampled can also affect the validity of the measurement and must be taken into consideration.     

基于改进R-R分布的现场激光粒度仪反演算法

针对现场激光粒度仪中颗粒粒径分布的反演计算方法,对非独立模式法中的R-R分布法进行了研究.同时设定多组R-R分布的尺寸参数X和分布参数M,采用多个线程同时反演计算目标函数(拟合误差).经过最后比较,找出函数值最小的目标函数,即认为现场颗粒的粒径分布服从该目标函数对应的R-R分布.现场激光粒度仪的实验结果表明,在使用5个线程时,每反演一次的平均时间小于1 min.该改进方法的原理简单,准确度和重复性高,计算速度快,能够满足现场颗粒粒径的实时测量要求.     

On-line Nonintrusive Measurement of Particle Size Distribution Through Digital Imaging

This paper presents the further development in the design and implementation of an innovative optical instrumentation system that can measure the size distribution of particles in a pneumatic suspension. A low-cost charge-coupled device (CCD) camera is used to capture the images of the particulate flow field, which is illuminated by a low-cost laser sheet generator. The particle size distribution is then determined by processing the particle images through the use of novel processing algorithms. Experimental results obtained on a small scale particle flow test rig have demonstrated that the system is capable of measuring the size distribution of pneumatically conveyed particles with repeatability better than 1% for a volumetric concentration up to 2%. A relative comparison is made between the on-line imaging technique and the widely accepted laser diffraction based particle sizing method. In addition to laboratory scale testing, results obtained in an industrial setting are presented and compared favorably with off-line reference values     

Particle Size Determination of a Three-Component Suspension Using a Laser-Scattering Particle Size Distribution Analyzer

In this study, a rapid and accurate particle size determination method using a light-scattering particle size analyzer was developed to measure the particle size and size distribution of a suspension containing three solid components: clotrimazole, triamcinolone, and sarafloxacin, which have different refractive indices. To ensure that data represent the size distribution of the primary particles of the suspension, the optimal sonication prior to and during measurement was detemined. It was found that the results obtained using the average relative refractive index (RRI) of the three components agreed with the results obtained using three individual RRIs. In addition, the results from two analysts demonstrated good reproducibility of this method. The size distribution data of the suspension were also compared to those of the bulk drugs. The results showed that the median particle size of this three-component suspension is relatively close to that of clotrimazole, which accounts for 80% of solid particles in the suspension. Furthermore, the results obtained using the light-scattering technique were comparable to those obtained using a polarized light microscope equipped with an image analyzer, indicating acceptable accuracy of this technique.     

Particle size determination of a three-component suspension using a laser-scattering particle size distribution analyzer

In this study, a rapid and accurate particle size determination method using a light-scattering particle size analyzer was developed to measure the particle size and size distribution of a suspension containing three solid components: clotrimazole, triamcinolone, and sarafloxacin, which have different refractive indices. To ensure that data represent the size distribution of the primary particles of the suspension, the optimal sonication prior to and during measurement was determined. It was found that the results obtained using the average relative refractive index (RRI) of the three components agreed with the results obtained using three individual RRIs. In addition, the results from two analysts demonstrated good reproducibility of this method. The size distribution data of the suspension were also compared to those of the bulk drugs. The results showed that the median particle size of this three-component suspension is relatively close to that of clotrimazole, which accounts for 80% of solid particles in the suspension. Furthermore, the results obtained using the light-scattering technique were comparable to those obtained using a polarized light microscope equipped with an image analyzer, indicating acceptable accuracy of this technique.     

多输出回归算法在超声粒径分布反演中的研究

悬移质粒径分布作为研究水体运动规律和水利建设中的关键参数,通过对Epstein-Carhart-Allegra-Hawley(ECAH)模型和超声衰减实验这类先验信息的研究,结合机器学习算法对悬移质颗粒粒径进行预测.根据超声衰减实验和其他相关物性参数提取特征,结合筛分法确定的粒径分布种类制作训练数据集和验证数据集,通过...     

多输出回归算法在超声粒径分布反演中的研究

悬移质粒径分布作为研究水体运动规律和水利建设中的关键参数,通过对Epstein-Carhart-Allegra-Hawley(ECAH)模型和超声衰减实验这类先验信息的研究,结合机器学习算法对悬移质颗粒粒径进行预测。根据超声衰减实验和其他相关物性参数提取特征,结合筛分法确定的粒径分布种类制作训练数据集和验证数据集,通过对单种粒径预测的梯度提升决策树(Gradient Boosting Decision Tree,GBDT)算法进行组合构建多输出回归算法对粒径分布进行预测。结果表明:三种样品单种粒径的最大相对误差在±10%以内,中位径误差分别为0.07%、?0.10%和?2.20%;在实验范围内,预测分布结果与筛分法结果一致,有较高的可行性和准确度,可为粒径分布测量提供一种新的思路。     

由 Mie 散射光强反演颗粒粒度分布的一种改进正则化法

基于Mie散射的激光粒度仪广泛地应用在颗粒粒度测量中,其中由光强分布演算出粒度分布的计算方法一直是关注的热点。此反演问题属于第一类Fredholm算子方程,具有不适定性,难以得出准确的稳定解,需要用高效的数值算法。本文提出一种应用于该类仪器颗粒粒度分布反演问题的改进正则化法,采用广义交叉验证法(GCV)来选择正则参数,并引入松弛技术,将迭代值加工成一种松弛值以改善精度,得出了稳定的正则拟解(近似解)。经标准颗粒的验证和计算机模拟证实,此算法是可行和有效的。     

Inverse scattering problem for mixed-phase and ice clouds. I. Numerical simulation of particle sizing from phase-function measurements

We propose a new method of particle size retrieval for mixed-phase and ice crystal clouds. The method enables us to identify each component of a bicomponent cloud composed of water droplets and ice crystals and to retrieve a size distribution separately for each cloud component. We explore the method's capability by using sythetic multiangular data of scattered-light intensity. We model cloud microphysical characteristics by assuming two noninteracting cloud components, such as liquid or supercooled droplets and cubic or hexagonal ice crystals, with regular simple geometrical shapes as first approximation. The sensitivity of the method is tested for different relative concentrations of the cloud components that are varied over a wide range. First, we investigate the applicability limit of the single-component cloud approximation in retrieving particle size distributions of a bicomponent cloud. Second, we test the method to retrieve size distributions simultaneously for both components in mixed-phase clouds, and we discuss the conditions of its applicability.