bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Particle Shape and Particle Size Distribution on fluidisation behaviour of granular activated carbon in the aqueous phase
Authors: van Lier Willem C. 
Published: May 2005

AbstractThis paper deals with the influence of particle shape and particle size distribution on the fluidisation behaviour of granular activated carbon in the aqueous phase. Methods for relating the degree of expansion, as a function of liquid velocity, to particle shape and particle size distribution are discussed and tested. Two different types of activated carbon, both containing irregularly shaped particles but with differences in shape, are used to test the models discussed. A tentative method which takes into account the influence of water temperature on fluidisation behaviour is proposed.
Data Reduction in Fluid Classification Methods
Authors: Svarovsky Ladislav , Mehrgan Hamid Reza 
Published: May 2005

AbstractFluid classification methods for particle size analysis are based on the concept of cut size. The particles suspended in a fluid are passed through several separation stages, of progressively finer cut‐size, so that each stage collects a fraction of the feed solids in the same way as each screen in a stack of sieves.There is an inherent error involved in the data reduction, which often leads to a poor comparison between the results of fluid classification and sedimentation, although both in principle measure the equivalent Stokes' diameter.This paper investigates the problem and attributes the above mentioned error to the difference between the equiprobable size and the analytical cut size. The paper presents a simple correlation which relates the analytical cut size and the equiprobable size if both the measured size distribution and the grade efficiency curve of the separator follow, approximately, log‐normal functions. The usefulness of the correlation is exemplified in the case of the Bahco analyser. Measured grade efficiency curves for each separation stage provide the necessary data for the above mentioned correction and this is then applied to examples of practical particle size analysis.
Particle Size Distribution Measurement by Automated Dual Wavelength Turbidimetry
Authors: Haseler Simon C. 
Published: May 2005

AbstractNumerous methods have been reported in the literature for the measurement of (submicron) particle size distribution by turbidimetry. Attempts to apply some of these to coupler dispersions (oil‐in‐water emulsions of importance in the photographic industry) have not in general proved satisfactory, however, because small experimental errors lead to relatively large errors in the calculated distribution. In order to reduce this problem a turbidimetric technique involving measurements at two widely separated wavelengths, 400 nm and 2.22 μm, has been developed. Its accuracy has been demonstrated using polydisperse polystyrene latexes of known size distribution. With the aid of simple, purpose‐built equipment, linked to a desktop computer, the technique has been largely automated so that it is suitable for use by an unskilled operator working in a factory environment.
The Fractal Nature of Dendrites Formed by the Collection of Particles on Fibers
Authors: Ensor David S. , Mullins Michael E. 
Published: May 2005

AbstractAerosols or particles suspended in air are often filtered by pads of fibers. The particles collect on the surface of the fibers in chain‐like structures called dendrites. An example scanning electron micrograph of 4.1 μm diameter particles captured on a 25‐m̈m fiber was analyzed by a Richardson plot. The Richardson plot is the measured perimeter of an image as a function of the length of measure or stride length. Three distinct regions were identified. For long and short stride lengths, the linear fiber and spherical particles were Euclidean. In the intermediate stride length region, the dendrite was fractal with a dimension of 1.36. The fractal nature of dendrites results from the random position of particles approaching the fiber and the shadowing effect of collected particles. Fractal geometry is potentially a useful approach for describing the morphology of the dendritic structures.
Photometric On‐line Measurement of Surface Area of Powders
Authors: Leschonski Kurt , Boeck Thomas 
Published: May 2005

AbstractAmongst the well known methods to measure surface area of particulate matter, preferably dry powders, only photometric methods can be used on‐line.The basic equation for the photometric measurement of surface area is Lambert‐Beer's law, which describes the attenuation of light (extinction) due to the presence of particles in a light beam. The attenuation being dependent not only on the size distribution of the particles in the light beam but also on their volume concentration. Since both effects alter the attenuation simultaneously the solids volume concentration has to be measured independently of the attenuation in a true on‐line system. The instrument developed combines the extinction of white light with the absorption of γ‐rays.Since the absorption of γ‐rays demands more particles in the measuring zone than the attenuation of light, an aerosol stream of rectangular cross section has been used which allows the simultaneous measurement of extinction and γ‐ray absorption.Apart from a brief description of the theoretical background of the instrument experimental evidence will be given of its suitability for on‐line application [1, 2].
Applications of Recent Advances in Fineparticle Characterization to mineral processing
Authors: Kaye Brian H. 
Published: May 2005

AbstractFineparticle Science is the study of the production and the behavior of finely divided material. In recent years the technology of fineparticle science has expanded rapidly. Many of the new innovations in that science have important applications in mineral processing. An important recent development in the mathematics of fineparticle science is the use of fractal descriptors to describe rugged boundries. In this communication the use of fractals to describe cracks in N dimensional space and potential applications of fractal descriptions in liberation kinetics are discussed. Fractals can also be used to describe the progress of a water front in a secondary oil recovery system. The use of divers to study concentration gradients in settling suspensions (tailing ponds) are described. New studies aimed at the optimization of on‐line quality control of grinding circuits are reviewed.
The Measurement of Spatial Aerosol Distributions in Enclosures by Means of computed tomography
Authors: Luck Heinz O. , Siemund Bernd , Lorbeer Gerhard 
Published: May 2005

AbstractA measurement method that approximates the spatial distribution of inhomogeneously distributed aerosols in a limited measurement plane is described. It is based on the evaluation of a comparably small number of infrared extinction measurements taken from the measurement plane boundary. The measured data are processed by means of computed tomography. The results are displayed on a monitor in a colour‐coded picture of the aerosol‐“density”‐pattern. The basic design and the principal characteristics of the method are mathematically described and verified by simulation tests and practical results which are obtained from an experimental set up using smoldering wood as an aerosol source.
Fractal Description of Extra Terrestrial Fineparticles
Authors: Kaye Brian H. , Clark Garry G. 
Published: May 2005

AbstractA technique for measuring the fractal structure of the rugged boundaries exhibited by lunar dust and a cosmic dust fineparticle captured at the outer limits of earth's atmosphere are measured using a equipaced polygon construction measurement procedure. The measurement procedure is described and data illustrating the precision and accuracy of the method are presented. The technique can be automated using inexpensive equipment and is suitable for use in teaching laboratories. Comparative data is presented establishing that the equipaced polygon procedure generates data comparable to that generated by the structured walk exploration technique. It is suggested that the fractal structure of extra terrestrial fineparticles may be of interest not only to the cosmologist but to the mining engineer since lunar dust represents fractured material not subjected to attrition polishing. Models used to simulate the generation of soot in combustion processes are discussed and it is demonstrated that diffusion limited aggregation Monte Carlo routines generate an agglomerate that appears to have similar fractal structure to the cosmic dust fineparticle collected by Brownlee. The data presented also indicates that one should use caution when relating the fractal dimension of a projected perimeter profile in two dimensions to the three dimensional structure of a rugged fineparticle.
Pore Structure Analysis of Porous Particles by Modelless and Micropore Method
Authors: Yan Ji‐min , Zhang Qi‐yuan 
Published: May 2005

AbstractThe modelless (ML) and micropore (MP) methods for the pore structure analysis of porous particles have been studied. Concerning the ML method, it has been shown that the Kiselev equation can only be used to describe condensation and evaporation in capillaries, but cannot be used to describe the increase and decrease of the thickness of the adsorption layer. Strictly speaking, therefore, the ML method is not modelless even for the pore core size distribution. A comparison between the ML method and methods using an equivalent pore model is given. The results of using the ML method in conjunction with a certain pore model are little less accurate than those obtained by adopting the equivalent pore model straightaway. The parameters required for the calculation of both the pore core size and the pore size distribution as well as the conversion between these two calculations are given.Concerning the MP method, it has been shown that the three types of v‐t curves, the theoretical foundation of the MP method, are not in one to one correspondance to the three kinds of adsorption mechanism. From the viewpoint of accuracy, the MP method has no advantage over the methods which are based on the condensation mechanism, both have their own merits.
Applications of Nuclear Magnetic Resonance Imaging in Particle Technology
Authors: Gladden Lynn F. 
Published: May 2005

AbstractDuring the past decade, the application of Nuclear Magnetic Resonance (NMR) imaging techniques to problems of relevance to the process industries has been identified. In the context of particle technology, NMR imaging, in addition to the more routinely used techniques of Pulsed Gradient Spin Echo (PGSE) NMR and NMR spectroscopy, offer new methods of characterising pore structure, adsorption and diffusion processes within particles and packed beds of particles, as well as enabling time‐resolved in‐situ study of processes such as twophase flow, aggregation, polymerisation, crystallisation and phase separation phenomena. This paper reviews recent work in these areas, and also highlights the new insights NMR imaging can give us regarding the characterisation of porous materials, and the influence of the structure of the pore space on the transport processes occuring within a given porous solid.
Particle Manipulation by Ultrasonic Standing Wave Fields to complement dynamic light scattering experiments
Authors: Holwill Ian L. , Davies Gareth B. , Titchener‐Hooker Nigel J. , Hoare Michael 
Published: May 2005

AbstractDynamic light scattering is a widely used technique for the sizing of colloidal suspensions. It is capable of measuring particles across the size range from approximately 1 nm to several microns. However the larger particle sizes tend to pose problems for the interpretation of the scattered light signal either by virtue of their light scattering efficiency relative to the smaller species present or the departure of the scattered light signal from Gaussian statistics. Rapid removal of such particles in‐situ could extend the use of dynamic light scattering particularly in on‐line analysis or laboratory automated measurement. In this paper a method is demonstrated for the in‐situ removal of larger particles in suspension by means of ultrasonic standing waves and concurrent dynamic light scattering measurement. The theory behind ultrasonic particle manipulation and its effect on the motion of the particles is discussed. Data from a scattering cell designed to incorporate the ultrasonic technology is presented showing that dynamic light scattering measurements may be carried out under such conditions. Varying the energy density of the ultrasonic field allows particles greater than a defined cut‐off diameter to be removed from the measurement region. Theory shows that the minimum cut‐off size may be as small as 100 nm. Results presented here demonstrate complete removal at a lower diameter threshold of approximately 2000 nm.
Comparative Test of Methods to Determine Particle Size and Particle Size Distribution in the Submicron Range
Authors: Lange Heinz 
Published: May 2005

AbstractAmong the most important characteristic properties of disperse systems such as latices, pigments, ceramic materials or drug formulations are the particle size and the particle size distribution. To measure these quantities, several methods and measuring instruments based on different physical principles are available. These include turbidimetry, dynamic and static light scattering, electron microscopy with image analysis, ultra‐ and disc centrifugation, light diffraction and the electrical sensing zone method. All these measuring techniques are doubtless necessary because of the large product variety and the broad particle size range. However, some problems arise if different techniques are used and the results are compared uncritically without considering to the application range and the resolution of the methods. An extensive comparative test was therefore carried out using seven latices in the submicron range with defined monomodal, bimodal and hexamodal particle size distributions. The most important methods of determining average particle size values and particle size distributions were tested and compared. Of the methods to determine only average particle sizes, turbidimetry is the most efficient, followed by dynamic light scattering with cumulants evaluation. Static light scattering only yields accurate results for small particles with narrow particle size distributions. Of the methods to determine particle size distributions, ultracentrifugation and, somewhat less, disc centrifugation and electron microscopy with image analysis are the most efficient. Dynamic light scattering only yields reliable results in the case of small particles with narrow distribution curves. Light diffraction and the electrical sensing zone method are less suitable for the submicron range.
Characterising the Dynamic Shape and Transport Behaviour of Coarse Particles
Authors: Brown Gareth J. , Miles Nick J. 
Published: May 2005

AbstractThe dynamic shape of coarse particles was determined by catastrophic tumbling studies performed in a rotating cylinder. Here, the dynamic shape was defined as the deviation from ideally regular and predictable tumbling behaviour.The data suggested that even with a comprehensive description of a static particle its transport properties cannot be accurately predicted.The fractal dimension in data space of the time series of events presents a method that can identify limits of predictability, and thus show regions that should be avoided to‐ minimise the emergence of chaotic behaviour.
Inlet Efficiency Study for the TSI Aerodynamic Particle Sizer
Authors: Kinney Patrick D. , Pui David Y. H. 
Published: May 2005

AbstractThe paper reports on the particle. sampling efficiency of the inlet system for the Aerodynamic Particle Sizer (TSI, Inc., St. Paul MN). Large particles are depleted from the sampled aerosol by two mechanisms: super‐isokinetic sampling at the entrance of the inlet, and inertial impaction on the inner nozzle. A fluorometric technique was used to separately characterize these mechanisms. Numerical studies were also performed. The experimental results show that the inlet's overall efficiency drops from around 90% for 3 μm particles to less than 45% for particles larger than 10 gm. Several high efficiency inlets were developed and tested. These inlets provide higher sampling efficiencies, but reduce the instrument's sizing resolution. Measurements of 7.3 μm oleic acid particles with a high efficiency inlet showed a 5% spread in measured diameter at 50% count, while less than a 1076 spread was observed using the standard inlet. It was also found that the super‐isokinetic condition reduces particle losses on the inner nozzle. The standard inlet is recommended for verifying test aerosol monodispersity. An alternative to the standard inlet is suggested for measurement of size distributions.
Particle Size Analysis: A comparative study of various methods
Authors: Etzler Frank M. , Sanderson Marie S. 
Published: May 2005

AbstractThe particle size distribution of component materials can be important parameter governing the proper function of many industrial products. At present, accurate determination of particle size by currently available methods is difficult for both theoretical and practical reasons. In this paper, some elementary notions regarding particle sizing are reviewed as is the relative performance of commercially available particle sizing instrumentation which could be used for particle size analysis of dry powders. Our results indicate that various particle size instruments yield significantly (even vastly) different particle size distributions for the same material. Without great care on the part of the investigator, the results obtained from any given instrument may not accurately describe the powder in question and thus may cause incorrect technical recommendations. The use of Fraunhofer diffraction instruments on samples containing irregularly shaped small ( < 10 μm) particles of low refractive index requires considerable caution.
Internal‐Field Characteristics of Spherical Particles
Authors: Kai Li , D'Alessio Antonio 
Published: May 2005

AbstractThe finely stratified sphere model was used to calculate electromagnetic fields inside homogeneous and radially inhomogeneous spheres which are illuminated by electromagnetic plane waves. A complete picture of the internal fields is given for spheres whose diameters are comparable to the wavelength (α = 1.5 and 5, where α = 2 πa/γs is the size parameter of the sphere) and spheres whose diameters are much larger than the, wavelength (α as high as 150), for coated spheres (spheres composed of a homogeneous core and a homogeneous shell) and gradient‐index spheres (spheres with a continuous of refractive index), for spheres at states of morphology‐dependent resonances (MDRs) and those at non‐resonant states.
Ultrasonic Measurement of Sub‐Micron Particles
Authors: Scott David M. , Boxman Arthur , Edwin Jochen C. 
Published: May 2005

AbstractBased on technology described in a Du Pont patent for an offline system, we have developed a prototype in‐line ultrasonic cell for measuring particle size distribution. We have used this cell to verify the Allegra‐Hawley model of ultrasonic attenuation in dilute (< 5 % vol) slurries of sub‐micron ceramic particles, and we are developing a model that can cope with the multiple scattering effects occuring at higher concentrations.In this paper we present the results of attenuation measurements for ultrasound (2–50 MHz) in slurries with concentrations ranging from 0.5 010 to 38 010 (vol). The attenuation is proportional to slurry concentration up to 5 010 (vol) and is predicted by single scattering models. Above approximately 100% concentration, the attenuation is actually lower than expected. For the dilute slurries we find excellent agreement between our measurements and the Allegra‐Hawley calculations, and the effects of the particle size distribution are evident in the ultrasonic attenuation spectrum. These ultrasonic data can be inverted to determine the particle size and concentration in aqueous slurries of sub‐micron particles.
The Use of Small Angle Light Scattering to Study Structure of Flocs
Authors: Jung Suk‐Jo , Amal Rose , Raper Judy A. 
Published: May 2005

AbstractIn this paper, a new approach using small angle light scattering to study the structure of large micron sized flocs is described. The flocs were made up from uniformly sized, approximately spherical hematite particles, induced to aggregate using 250 mM KCl to ensure that growth was governed by diffusion limited aggregation alone. The fractal dimensions of the hematite aggregates changed from 1.73 to 2.23 ± 0.05 as the aggregation proceeded, indicating that restructuring occurred during aggregation. The fractal dimensions obtained from the small angle light scattering technique are compared with those obtained from the combination of volume fraction and floc size measurement. The steady state fractal dimensions (2.23 ± 0.05) obtained by small angle light scattering are comparable to the fractal dimensions obtained from determining the slope of the relationship between floc volume fraction and floc size (2.09 and 2.14 ± 0.05). The discrepancy between the fractal dimensions obtained by these techniques during the initial stages of aggregation is due to the fact that the latter method measures the average fractal dimensions, whilst the former method measures the fractal dimensions at any particular instant.
On‐Line Simulation as a Methodology to Recover Size Distributions from dynamic light scattering experiments
Authors: van Criekinge Wim , van der Meeren Paul , Vanderdeelen Jan , Baert Leon 
Published: May 2005

AbstractIt is generally recognized that fundamental limitations make data analysis for dynamic light scattering (DLS) not straightforward. In addition to experimental problems such as multiple scattering, number fluctuation and noise, there are intrinsic problems. Data analysis is a so‐called reverse problem which, owing to the mathematical equations, becomes “allergic” to noise (an ill‐posed inverted problem). In an attempt to overcome at least some of these limitations, a software solution was developed. This mainly aimed to implement a tool that makes it easy to evaluate physically plausible solutions, rather than to determine many (less accurate) parameters related to the size distribution. One of the major goals was to create a “white‐box” program. The software is in essence an easy‐to‐use graphical interface between user and computer. The most important motivation to apply the concept of on‐line simulation is the limited information content of DLS autocorrelation functions. In the present approach, the user, rather than the software, has to evaluate the physically plausible solutions and select the most appropriate one. The computer becomes a mirror that calculates but leaves the decision making to the user. Using this software environment, the resolving power of the technique in ideal and noisy conditions was investigated. Results were obtained for monomodal samples where the mean diameter seems to be far more reliable than the polydispersity. For bimodal samples, the convergence of the solution to a monomodal distribution was observed when the noise level increased. The goal is to put into perspective the results as obtained in most “black‐box” software without having to use heavy mathematical approaches. One of the major applications is the use of the program as an interactive introductory tool to become acquainted with the power and, above all, with the limitations of DLS.