bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Characterisation of Particles Using the Settling Rate dependent movement in two phase flows
Authors: Leschonski Kurt 
Published: December 2004

AbstractThe drawback of conventional sedimentation methods, mainly their extremely long sedimentation time for small particles, can be overcome in two phase flow systems. In this paper several principles which permit the rapid determination of settling rate distributions are discussed. Settling rate distributions can be determined from the accelerated particle movement in a flow of constant velocity at low and high solids concentrations. Another system uses accelerated flow at low solids concentrations. The best utilisation of settling rate applications have socalled cross flow systems as set up in a stagnation point flow, in a flow round a bend, or in the decelerated particle movement perpendicular to a flow of constant velocity.
Dense Monolayers of Monodisperse Opaque Spheres: Transmission and diffraction in the fraunhofer domain
Authors: Riebel Ulrich , Hickl Peter 
Published: December 2004

AbstractThe transmission and diffraction of radiation through dense monolayers of monodisperse opaque spheres were studied for the Fraunhofer domain. Theoretical considerations, numerical calculations and experiments on ultrasonic transmission and on laser light transmission and diffraction yielded corresponding results. Complementary studies included the cases of sterically non‐interacting particles (by numerical simulation) and of small particle size parameters (by ultrasonic extinction). Transmission was found to be, in general, a non‐linear function of the monolayer density. Secondary effects on the transmission can be attributed to the effect of the monolayer structure (characterized by the pair correlation function) on the angular distribution of diffracted intensity. The results were found to be in accordance with experimental results on extinction in three‐dimensional systems.
Neural Networks for Flow Regime Identification with dry particulate flow
Authors: Bidin Abdul Rahman , Green Robert G. , Shackleton Mary E. , Taylor Richard W. 
Published: December 2004

AbstractThis work on imaging of particulate processes using electrical charge tomography uses two basic techniques: the multi‐sensing of electrical charge in a cross‐section of the flow pipe and a neural network based flow regime identification system to aid in the image reconstruction process.A measurement system, consisting of sixteen sensors, placed at equal distance from each other around the boundary of a circular 100 mm bore pipe, is used to determine the voltage profile of the flow for several artificially produced flow regimes: full, annular, core, half and stratified. A sand flow system is used to produce these different flow regimes, which are created artificially by using baffles of different shapes that obstruct the sand flow.The voltage profile from the sixteen sensors gives spatial information of the flow regime. These profiles are normalised and formed into patterns that are presented to a Kohonen neural network for classification. Two regime classification between clearly distinct regimes gives an accuracy of identification of 85%. Classification of closely similar patterns show much less accuracy of 30%.
Ensemble and Single Particle Laser probe sizing results for gas atomized zinc powders
Authors: Boyko Christina M. , Le Tuyet H. , Henein Hani 
Published: December 2004

AbstractOn‐line characterization of powder and droplets during gas atomization of molten metals and alloys offers extensive opportunities for real‐time process monitoring and control. The capability to make on‐line measurements can significantly reduce tedious and costly powder classification, which, currently, is always carried out subsequent to the atomization process. Two laser‐based particle sizing instruments, the EPCS (ensemble instrument) and PCSV (single particle instrument), were used during gas atomization of zinc with a double Coanda nozzle configuration. The laser instruments were positioned in the duct leading from the bottom of the atomization tower to the powder collection cyclone. The effect of gas to metal ratio on particle size was studied by varying the atomization gas pressure from 0.69 MPa to 1.03 MPa. Air was used as the atomizing gas for some of the 0.69 MPa runs, while nitrogen was used for all of the higher‐pressure runs. Experimental apparatus and procedures for atomization and on‐line powder sizing with the EPCS and PCSV are described. EPCS and PCSV measurements, which were compared with standard sieve analyses, indicate that the ensemble instrument is a good candidate for on‐line process monitoring and control.
Generalized lorenz‐mie theory and applications
Authors: Gouesbet Gérard 
Published: December 2004

AbstractMany optical sizing techniques rely on particle/laser interactions. The classical Lorenz‐Mie theory describing sphere/plane wave interactions is therefore misleading when designing instruments and processing data when the particle size is not small enough with respect to beam diameters. In such cases the use of the generalized Lorenz‐Mie theory is required. After summarizing essential features of the generalized Lorenz‐Mie theory for sphere/arbitray wave interactions, this paper describes applications of the theory with some emphasis on the analysis of phase‐Doppler anemometers.
Coherent Scattering by Multiple Particles in Phase Doppler Interferometry
Authors: Sankar Subramanian V. , Ibrahim Khalid M. , Bachalo William D. 
Published: December 2004

AbstractA theoretical model has been developed for studying the response of the phase Doppler interferometer when multiple particles are simultaneously present within the measurement probe volume. The developed model incorporates the geometrical optics theory for describing the coherent interaction between the scattered light signals of multiple particles, eachhaving different size, velocity, trajectory, and arrival time. The resulting Doppler signal is processed by a theoretical signal processor which can simulate the performance characteristic of different signal processing schemes that are widely used in phase Doppler interferometry, namely, zero‐crossing counter, covariance, autocorrelation and DFT parocessors. The application of the developed model for studying the coherent scattering by two particles has been specifically addressed in this paper. It has been shown that a DFT processor can be used to simultaneously measure the size and velocity of the two particles in most instances. However, for more than two particles, the signal processing scheme becomes more complex because of a quadratic increase in the beat frequency components.
Particle Image Velocimetry Applied to a Spray Jet
Authors: Brandt Andreas , Merzkirch Wolfgang 
Published: December 2004

AbstractExperiments are described in which particle image velocimetry (PIV) is applied to the measurement of liquid droplets in a spray jet. The two velocity components in planes formed by the light sheet originating from a double‐pulsed ruby laser are determined. The PIV records are evaluated with the method of Young's fringes. It is shown that this procedure allows the simultaneous measurement of the droplet size within a certain size range.
Design and Performance of an Ultrasonic Atomization System for experimental combustion applications
Authors: Lacas François , Versaevel Philippe , Scouflaire Philippe , Coeur‐Joly Gérard 
Published: December 2004

AbstractAlthough common atomizing systems efficiently produce sprays, a range of droplet sizes is generally obtained and the distribution is often difficult to control in terms of liquid or gaseous flow rates. It is shown that an alternative system, based on ultrasonic surface instabilities, is well suited for experimental applications where all parameters have to be controlled. Technological aspects of ultrasonic atomization are described and the droplet spray produced by an ultrasonic atomizer is characterized experimentally.
Particle size Effects on Optical Transport through strongly scattering media
Authors: Dogariu Aristide , Uozumi Jun , Asakura Toshimitsu 
Published: December 2004

AbstractMeasurements of transmission and enhanced backscattering from powder beds of α‐AI 2O3 consisting of particles with different average sizes are reported. The values of the mean free path and the absorption length, as inferred from these measurements, are compared and good agreement between the two measurement is found when the internal reflections are properly taken into account. A particle size measurement method is suggested on the basis of the linear dependence found experimentally between the transport mean free path and the mean particle size.
A Light Scattering Study of Coal Combustion in a Drop Tube Furnace
Authors: Card Jacqueline B. A. , Jones Alan R. 
Published: December 2004

AbstractA light scattering method has been devised to discriminates between coal and fly ash and measure particle size. Sizing was performed by the measurement of forward scattered intensity, and discrimination was displayed by the ratio of the intensities of crossed to parallel polarisations at a scattering angle of 160°. The technique has been applied to a study of coal combustion in a variable length drop tube furnace. It has been demonstrated that the development of the size distribution can be followed as a function of residence time. Further, it is indicated that there is a simple correlation between the polarisation ratio and the carbon content of the ash. This leads to the possibility of monitoring combustion efficiency in industrial furnaces.
Computerised Perimeter Mapping and the Measurement of Fractal Dimensions
Authors: Adler Jeremy 
Published: December 2004

AbstractA method is described for mapping the perimeter of shapes as a sequence of connected X & Y coordinates. It operates by tracking, in tandem, along a dilated outline of the shape and the true outline, maintaining contact between both tracks. This combination permits the complete mapping of binary shapes regardless of their complexity. The resulting sequence of X & Y coordinates form an 8‐connected map of the outline, which can then be used to obtain fractal dimensions using structured walks. The method requires a digitised image that has been converted into a binary form and the ability to read the values of individual pixels from the digitised binary image. In addition a number of approaches for increasing the efficiency of the twin tracking algorithm are outlined.Obtaining fractal dimensions from a structured walk based on a fully mapped perimeter increases the accuracy of the measured fractal dimensions, extends the range of step sizes over which measurements can be made and permits a highly detailed examination of the perimeter.
Continuous Mixing of Fine Particles
Authors: Weinekötter Ralf , Reh Lothar 
Published: December 2004

AbstractThe efficiency of reactors fed with particulate mixtures is often reduced by segregation of solids. Placing continuous mixers directly ahead of a reactor may be a solution to this problem. The performance of such mixers can be monitored for appropriate binary solids systems with an optical in‐line measuring system. The tracer concentration (SiC or Irgalite) in Al(OH)3 was registered with high time resolution, thus making possible an extended statistical analysis of mixing processes using the power density spectrum. Experimental mixers with a maximum ‐throughput of 300 kg/h were fed with a fluctuating tracer concentration and the variance reduction ratios were determined. A model was developed that takes into account feeding constancy, residence time distribution and the limited homogeneity of particulate mixtures. Diagrams for continuous solids mixing processes are derived therefrom. They demonstrate the importance of high‐accuracy feed‐rate control.
Analysis of sequence–reactivity space for protein–protein interactions
Authors: Li Jiangtian , Yi ZhengPing , Laskowski Michael C. , Laskowski Michael , Bailey‐Kellogg Chris 
Published: December 2004

AbstractSequence–reactivity space is defined by the relationships between amino acid type choices at some residue positions in a protein and the reactivities of the resulting variants. We are studying Kazal superfamily serine proteinase inhibitors, under substitution of any combination of residue types at 10 binding‐region positions. Reactivities are defined by the standard free energy of association for an inhibitor against an enzyme, and we are interested in both the strength (the free energy value) and specificity (relative free energy values for one inhibitor against different enzymes). Characterizing the structure of such a space poses several interesting questions: (1) How many sequences achieve particular strength and specificity characteristics? (2) What is the best such sequence? (3) What are some nearly‐as‐good alternatives? (4) What are their common residue type characteristics (e.g., conservation and correlation)? Although these problems are all highly combinatorial in nature, this article develops an efficient, integrated mechanism to address them under a data‐driven model that predicts reactivity for given sequences. We employ sampling and a novel deterministic distribution propagation algorithm, in order to determine both the reactivity distribution and sequence composition statistics; integer programming and a novel branch‐and‐bound search algorithm, in order to optimize sequences and enumerate near‐optimal sequences; and correlation‐based sequence decomposition, in order to identify sequence motifs. We demonstrate the value of our mechanism in analyzing the Kazal superfamily sequence–reactivity space, providing insights into the underlying biochemistry and suggesting hypotheses for further experimental consideration. In general, our mechanism offers a valuable tool for investigating the available degrees of freedom in protein design within a combined computational–experimental framework. Proteins 2005. © 2004 Wiley‐Liss, Inc.
Refinement of X‐ray data on dual cosubstrate specificity of CK2 kinase by free energy calculations based on molecular dynamics simulation
Authors: Setny Piotr , Geller Maciej 
Published: December 2004

AbstractFree energy differences of binding of adenosine triphosphate (ATP) and guanine triphosphate (GTP) to the protein kinase CK2 (casein kinase 2) were calculated, using molecular dynamics (MD) simulations and the thermodynamic cycle approach. Good agreement with experimental data was obtained. Simulations confirm observations based on crystallographic data that specifically interacting water molecules in the binding site region of CK2 kinase play a key role in its ability to use ATP or GTP as equally efficient phosphate donors. We point out that to obtain quantitatively reasonable results, it was necessary to modify original X‐ray data by assuming the presence of an additional water molecule in the CK2 binding site structure with GTP. Proteins 2005. © 2004 Wiley‐Liss, Inc.
Chemisorption of sulfur dioxide on tungsten and platinum surfaces
Authors: Wu Owen K. T. , Burns Richard P. 
Published: December 2004

AbstractThe chemisorption of SO2 on a W and a Pt surface has been investigated by flash desorption mass spectrometry (FDMS) and AES. AES data indicate that the chemisorbed sulfur dioxide molecules oxidized the W surface, and produced a stable tungsten oxide during the heating (up to 1400 K) process. FDMS data indicate that the decomposition of SO2 yielded elemental and molecular sulfur during the desorption process. FDMS data show that SO2 exists in four binding states (α1, α2, α3 and α4) on a clean Pt surface and in three binding states (α5, α6 and α7) on an oxidized Pt surface. In addition, the coadsorption of SO2 and O2 was carried out on a Pt surface. The coadsorption process can produce SO3 which exists in two different binding states on a Pt surface. The data indicate that the oxidation of SO2 to form SO3 on a Pt surface occurs by means of a Langmuir–Hinshelwood mechanism.
The surface analysis of insulators by SIMS: Charge neutralization and stabilization of the surface potential
Authors: Hunt C. P. , Stoddart C. T. H. , Seah M. P. 
Published: December 2004

AbstractAs part of an ongoing programme of reference work for surface analysis at the NPL, the problem of surface charging when analysing insulators by static SIMS is discussed. Meaningful analysis requires stabilization of the surface potential to a defined reference point, here taken as the potential that would exist if the insulator was a conductor. In SIMS spectra it is shown that both the absolute and relative intensities of peaks depend on the surface potential. It is also shown that, only by the correct design of an electron flood source, can the surface be stabilized to a given constant reference potential. The relevant design principles are illustrated by measurements on isolated targets which define the characteristics of the flood source. Stabilization is effected to within the ±0.5 eV required for static SIMS.
Quantitative auger electron spectroscopy of metal monolayers on metals: Evidence for adsorbate/substrate interface effects
Authors: Rhead G. E. , Argile C. , Barthès M.‐G. 
Published: December 2004

AbstractA critical appraisal is made of quantitative AES data obtained for some 30 metal monolayer on metal systems, and in particular for lead and tin monolayers on four substrate elements that have Auger emissions in the energy range 62–72 eV: Ni, Cu, Al, Au. The general agreement for a particular set of data tends to confirm the values of various monolayer densities from LEED but there are very significant differences between the attenuation (of the emissions close in energy) produced by the same overlayer on the different substrates. The emissivity of the overlayer metal may also depend on the nature of the substrate. It is concluded that several factors may affect the detected Auger emissions, including the influence of the absorbate/substrate interface on electron scattering and in particular on the back‐emission into the crystal. As a consequence it appears that quantitative analyses via the use of elemental AES emissivities and attenuation factors may be unreliable.
A modulation technique for discrimination against ion induced auger electrons in micro‐area AES
Authors: Ward I. D. , Blattner R. J. 
Published: December 2004

AbstractBeam brightness modulation Auger spectrometry is shown to be an effective means of eliminating ion induced Auger electrons from Auger electron energy spectra. Modulating the incident electron beam intensity causes the true electron induced Auger electron emission to be modulated at the beam modulation frequency which can be easily separated from the unmodulated ion induced Auger electrons by means of frequency sensitive detection using a lock‐in amplifier. This technique is particularly useful when depth profiling with a high energy ion beam (∼5 kV) and a low current (small spot) electron beam (<100 nA).
Quantitative Auger electron spectroscopy for refractory metal silicides
Authors: Wirth Th. , Procop M. , Lange H. 
Published: December 2004

AbstractQuantitative AES analysis is carried out on Cr–Si and Mo–Si systems. The treatment is based on the introduction of matrix and sputter correction factors. The matrix correction factors are calculated along the lines outlined in literature and proved to be weakly dependent on composition. Comparison with experimental data obtained on scratched surfaces of MoSi2 and Cr3Si bulk samples showed good agreement between experimental and nominal composition ratios. The sputter correction factors were found to be strongly dependent on composition for both systems. Comparison with theory for the case of preferential sputtering as the dominant ejection mechanism yields agreement with the experiment only for samples with low Si content. This is believed to be due to superposition with recoil location of the heavier component.
A quantification and investigation of surface microporosity in carbon fibres using labelling and XPS
Authors: Dension P. , Jones F. R. , Watts J. F. 
Published: December 2004

AbstractAn investigation is presented into the surface microporosity of Type 1 carbon fibres, with a range of oxidative treatment levels, and in which trichloromethane labelling and XPS analysis is used. Detection of the halogen atoms in molecules retained in the micropores shows that the oxidation‐dependent micropore volume is 2–13 × 10−5 cm3 per gram of fibre, which is in the expected range from results given in the literature. The model of the carbon fibre surface previously reported has been extended and it is proposed that the functional groups are bound to edge carbon atoms in the micropores. This is shown to be consistent with structures given by other workers, from x‐ray diffraction and electron microscopy.
Identification of synthetic metals from the shape of the carbon KLL spectra by the pattern recognition method
Authors: Lesiak B. , Jablonski A. , Zagorska M. , Jozwik A. 
Published: December 2004

AbstractThe aim of the work was to verify the possibility of application of Auger electron spectroscopy in connection with the pattern recognition method to study the polymer surfaces. Synthetic metals were chosen for investigation. The carbon KLL spectra were analysed using the so‐called k‐nearest neighbour rule. Analysis was performed for polyacetylene and polypyrrole doped with Fe(CN) and FeCl4− ions. On the basis of the standard spectra recorded for all polymers the effective recognizing procedure was developed. Noticeable changes of spectra were observed on electrochemical removal of dopants. The analysis made after 90 days of ageing in vacuum revealed some spectra changes in doped polymers. These change may be due to the disappearance of dopants or to the deposition of contaminants. An electron beam of 300 nA at 1000 eV was found to affect the surface of polyacetylene.
Evaluating precursor processing of Ba2 YCu3O7 – y Compounds Using High‐Resolution Scanning Auger Microscopy
Authors: Moore Richard L. 
Published: December 2004

AbstractSuperconducting materials, particularly the rare earth perovskite compounds have been shown recently to be the most promising materials for high Tc applications. Numerous techniques have been utilized to study the composition and structure of these materials. Of particular interest is the microstructure and grain boundaries. Consequently, the analytical technique must have sufficient spatial resolution to distinguish grain boundaries and the ability to characterize those grain boundaries, as well as the adjacent microstructure.This work will present a study in microstructure and grain boundary composition using high resolution scanning Auger microscopy. Electron‐beam degradation of these compounds was evident. However, using cation ratios circumvented this problem in the scope of this investigation. By correlating electronic properties to a specific microstructure and composition, we can prescribe processing which optimizes the formation of the preferred crystal structure or phase.