Rough Particle Research Articles

Lithium ion conductivity of the B-site substitution in Li3xLa0.67−xRE y III Ti1−2yPyO3 system (REIII=Sc3+, Y3+, Nd3+, Sm3+, Eu3+, Yb3+)

The B-site substituted perovskite solid solution systems Li3xLa0.67−xREyTi1−2yPyO3 (RE=Sc, Y, Nd, Sm, Eu, Yb) have been investigated. Perovskite solid solutions formed in the range of x=0.10, y<0.10 for RE=Sc3+, Y3+, Yb3+, x=0.10, y≤0.05 for RE=Nd3+, Sm3+, Eu3+. Li0.3La0.57Nd0.05Ti0.9P0.05O3 has the highest bulk conductivity of 4.31×10−4 S·cm−1 and the highest total conductivity of 2.52×10−4 S·cm−1 at room temperature in all prepared compositions. The compositions have low activation energies of about 24–30 kJ/mol in the temperature ranges of 298–523 K. SEM studies showed that the sample made by solid-state reaction has a sphere-like morphology and a rough particle with particle size of about 50 µm. The research results also indicated that the reaction temperature decreases and the electrochemical stabilities of the titanate-based perovskite-type solid solutions are improved by using RE3+ and P5+ replaced Ti4+ on B-site in the Li3xLa0.67−xTiO3 parent.

Particle Trajectory in Turbulent Boundary Layer at High Particle Reynolds Number

Particle Trajectory in Turbulent Boundary Layer at High Particle Reynolds Number

A comparison of the flotation of ore from the Merensky Reef after wet and dry grinding

The effect of dry and wet grinding on the flotation of complex sulfide ores from the Merensky Reef in South Africa was investigated. Topographical examination of the ground particle surfaces by scanning electron and atomic force microscopy showed that the dry ground samples had relatively rough particle surfaces with a high concentration of microstructural defects, while the wet ground samples had smoother, cleaner surfaces. As a result, the activated particle surfaces from the dry ground ore accelerated the dissolution of the particles, as well as the adsorption of reagents onto the particle surfaces. The dry ground samples exhibited more stable, higher loaded froths and faster flotation kinetics, owing to the activated particle surfaces. High intensity conditioning of the dry ground ores prior to flotation could improve flotation by cleaning the particle surfaces through high shear force fields in the pulp. Moreover, by combining dry and wet grinding, the kinetics, as well as the final grades and recoveries of the sulfides, could be improved.

Modeling of the Dispersion Force and Experimental Study of Influence of Dispersion Stress

The dry dispersion is the deglomeration of fine aggregate particles in an air stream. It is necessary for deglomeration that the existing van der Waals adhesive forces are smaller than the dispersion force. The angle-dependent dispersion force on a model aggregate particle was theoretically analyzed for the acceleration in an air stream. The stress by the angle-dependent dispersion force and the centrifugal force is compared with the mean adhesive force of the agglomerate. The derived dispersion model is able to give a decision whether the model agglomerate can be dispersed due to the stress in the flow. The theoretical results were checked and proved by experiments with three materials. A high stress and a real rough particle surface is the prerequisite for dispersion of fine particles.

10.1109/ICCMS.2010.188

The evaluation of intelligent decision making is a key quagmire. Given the current status of intelligent decision making archetypes, analysts clearly desire the rough sets and particle swarm optimization, which embodies the practical principles of cryptography. Our focus in our research is not on whether the intelligent decision making problem and the rough sets are rarely incompatible, but rather on proposing an analysis of optimal method for intelligent decision making.

The Effect of Nanoscale Roughness on Long Range Interaction Forces

A model was developed to calculate the long range van der Waals and electrostatic energies between a rough colloidal particle and a smooth solid plate in aqueous solutions. The particle roughness was modeled as hemispherical asperities distributed uniformly over the surface. Because of the assumption of additive potentials used in calculating the electrostatic force, the model is most accurate when the particle/plate separation is larger than several Debye screening lengths, such as near the location of the secondary minimum. The model predicts that such roughness reduces the depth of the secondary minimum and pushes it to larger separation distances. The model also predicts that the height of the primary energy barrier, which controls the dispersion stability, is substantially lowered by the asperities.

Coherent detection of enhanced back-scatter from rough surfaces and particle suspensions

Abstract Coherent detection has been used to measure enhanced back-scatter from a range of rough surfaces and particle suspensions. Strong enhancement peaks have been observed from suspensions of monodisperse spheres at concentrations as low as 0.2%. This low-density regime has not been accessible to earlier (direct-detection) techniques. The possibility of using measurements of the enhancement peak to characterize rough surfaces or to size particles is discussed and the cross-polar returns from a tutorial target are also measured.

Coherent detection of enhanced back-scatter from rough surfaces and particle suspensions

Coherent detection has been used to measure enhanced back-scatter from a range of rough surfaces and particle suspensions. Strong enhancement peaks have been observed from suspensions of monodisperse spheres at concentrations as low as 0.2%. This low-density regime has not been accessible to earlier (direct-detection) techniques. The possibility of using measurements of the enhancement peak to characterize rough surfaces or to size particles is discussed and the cross-polar returns from a tutorial target are also measured.

Influence of surface roughness of conducting spheres on the response of a phase-doppler anemometer

The influence of the surface roughness of solid conducting spheres calculations of the PDA phase difference. The numerical on the response of a phase-Doppler anemometer (PDA) is simulations are accompanied and supported by experimental described by using a ray theory model. A rough particle surface results. Single rough Sn spheres are captured inside an electrois modeled as an ensemble of distorted spheres. First- and second- dynamic trap and investigated with a standard phase-Doppler order reflection and diffraction are considered for far-field system.

Automated high-speed Mueller matrix scatterometer

A new scatterometer-polarimeter is described. It measures the angular distribution of intensity and of the complete Mueller matrix of light scattered by rough surfaces and particle suspensions. The measurement time is 1 s/scattering angle in the present configuration but can be reduced to a few milliseconds with modified electronics. The instrument uses polarization modulation and a Fourier analysis of four detected signals to obtain the 16 Mueller matrix elements. This method is particularly well suited to online, real time, industrial process control involving rough surfaces and large particle suspensions (an arithmetic roughness or particle diameter of >1 microm). Some results are given.

Complete high-frequency measurement of Mueller matrices based on a new coupled-phase modulator

A new polarization modulator is presented. It uses two phase-locked identical electro-optic phase modulators at 50 kHz. Thanks to a coupling object introduced between the two phase modulators, the four Stokes parameters of the light beam are independently modulated on the basis of the first and second complex harmonics of the modulation signal. A Mueller matrix ellipsometer (MME) using this new modulation and a multichannel polarimeter are also described. The data processing and the feedback control of Pockels cells is based on a numerical Fourier transform system. It allows one to measure simultaneously, in one modulation period (20 μs), the 16 coefficients of any Mueller matrix. This MME takes advantage of an easy-to-operate calibration method. The high-frequency modulation of the four parameters of the polarization enables low-light-level measurements (without any chopper and lock-in) and presents spectroscopic capabilities. It provides a promising tool for the study of many subjects of growing interest like, for example, rough surfaces treatment or particle characterization.

Histochemical and Cytochemical Studies on Newt Lung Mast Cells.

Mast cells which show metachromasia with toluidine blue were observed in newt (Cynops pyrrhogaster) lung connective tissue. The mast cells showed strange granules in their cytoplasm. In this study, we examined the characteristics of the mast cells by using histochemical and cytochemical methods.The mast cells were positive for PAS reaction and Alcian blue (pH 1.0). Electron microscopy showed that the mast cells stretched their cytoplasm into the collagen layer. The cytoplasm was filled with various types of granules, some homogeneous throughout, others heterogeneous, and were classified as follows: high and low electron density amorphous structure, straight lamella structure, and rough particle structure. These granules were irregular in size. They were stained by alkaline bismuth and dialyzed iron. The rough particle structure granules in particular showed stronger staining than others.In order to determine which sulfated polysaccharide was contained in the granules, we performed enzyme treatment using two enzymes chondroitinase ABC (pH 8.0) and heparinase. Our results indicated that the granules contained heparin.

Experiments on particle—turbulence interactions in the near–wall region of an open channel flow: implications for sediment transport

A high-speed video system was used to study the interaction between sediment particles and turbulence in the wall region of an open channel flow with both smooth and transitionally rough beds. In smooth flows, particles immersed within the viscous sublayer were seen to accumulate along low-speed wall streaks; apparently due to the presence of quasi-streamwise vortices in the wall region. Larger particles did not tend to group along streaks, however their velocity was observed to respond to the streaky structure of the flow velocity in the wall region. In transitionally rough flows particle sorting was not observed. Coherent flow structures in the form of shear layers typically observed in the near-wall region interacted with sediment particles lying on the channel bottom, resulting in the particles being entrained into suspension. Although there has been some speculation that this process would not be effective in entraining particles totally immersed in the viscous sublayer, the results obtained demonstrate the opposite. The entrainment mechanism appears to be the same independent of the roughness condition of the bottom wall, smooth or transitionally rough. In the latter case, however, hiding effects tend to preclude the entrainment of particles with sizes finer than that of the roughness elements. The analysis of particle velocity during entrainment shows that the streamwise component tends to be much smaller than the local mean flow velocity, while the vertical component tends to be much larger than the local standard deviation of the vertical flow velocity fluctuations, which would indicate that such particles are responding to rather extreme flow ejection events.

Effect of Surface Roughness on the Interaction Energy between a Colloidal Sphere and a Flat Plate

A set of analytical equations are developed for calculating the van der Waals and electrostatic interaction energies between a rough spherical particle and a smooth plate. The particle roughness is modeled as hemispherical asperities of fixed radius, in agreement with SEM micrographs of polystyrene latex spheres. The van der Waals energy is calculated using a pairwise summation technique for both nonretarded and retarded cases. The electrostatic energy is calculated using the linear superposition approximation and assuming the asperity-plate and particle-plate interactions are additive. We find that at large separations, the increased electrostatic repulsion produced by the roughness results in a shallower secondary potential well. At closer separations, however, the increased van der Waals attraction produces a dramatically lower repulsive barrier (as much as two orders of magnitude smaller in the example presented). This lower barrier would yield much larger capture rates than predicted by DLVO theory for smooth surfaces, in qualitative agreement with experimental observations.

Electric dipole absorption by ballistic electrons in small metal spheres

We describe a semiclassical approach to estimating the absorption of electromagnetic radiation by small conducting spheres, in which the motion of the charge carriers is ballistic. The results are strikingly different between the cases of rough and smooth walled particles. For a rough walled particle the absorption coefficient is proportional to omega 2 in the low-frequency limit. For a smooth walled sphere the absorption coefficient has a low-frequency cut-off at omega c, the angular frequency of a circumferential 'whispering gallery' classical orbit of a carrier at the Fermi surface. At frequencies above omega c the spectrum consists of a sequence of overlapping resonance bands which combine to give an absorption coefficient proportional to omega 2 only for omega >> omega c.

Simultaneous ozone and polar stratospheric cloud observations at South Pole station during winter and spring 1991

Simultaneous polar stratospheric cloud (PSC) and ozone measurements were made over South Pole Station using a two‐wavelength backscattersonde. This instrument produces aerosol profiles similar to those obtained with a ground‐based lidar system but with higher vertical resolution. In one sounding, depolarization of the PSCs was also measured. The backscattersondes were supplemented with occasional frost point soundings. The measurements made before the appearance of PSCs do not show clear evidence of particle deliquescence, suggesting that the background sulfate particles may be frozen solids rather than liquids. PSCs began appearing at ∼20 km when the temperature at that altitude dropped to −80°C (193 K). Initially, there was apparent evidence of supersaturation (with respect to nitric acid trihydrate) associated with some type I PSCs, while other examples indicated that the condensation of nitric acid was in quantitative agreement with that expected from the saturation vapor pressure and available nitric acid vapor. The apparent supersaturated layers (which occurred within the first 2 weeks of the onset of PSCs) can alternatively be interpreted as denitrified regions. The wavelength dependence of the backscatter is used to deduce rough particle sizes, and in particular, type Ia and Ib population types can be readily identified by the backscattersonde when not occurring as mixed systems. The mode radius of the first observed PSCs of the season was ∼0.5 μm. In the polarization sensitive sounding, two varieties of type I PSCs were observed, one of which exhibited significant depolarization and another which produced very little depolarization. This observation would be consistent with the classification of types Ia and Ib, respectively. At the precise time that sunlight was returning to the stratosphere near South Pole Station, a strong inverse correlation in the structure of PSCs and ozone mixing ratio was observed. Using trajectory analysis, it is argued that the effect is probably the result of chemical depletion rather than transport processes. This chance observation is consistent with enhanced ozone depletion occurring in association with sunlit PSCs during the early spring.

Burning Rate Prediction of Composite Solid Propellants Using Fractal Geometry

Abstract An investigation of the effects of Ammonium Perchlorate (AP) surface “roughness” on the burning rate predictability of the “Petite Ensemble Model” (PEM) has been undertaken. By using fractal geometry, it is possible to compensate for the surface roughness of AP in the surface area relations of the PEM burning rate model of composite solid propellants. This fractal geometry approach required an estimate of the fractal dimension or the interface between the oxidizer (AP) and the binder. With the use of this dimension, the surface area relations developed for a spherical oxidizer were then generalized for a rough particle. This generalization was implemented in the PEM burning rate model, which was executed for a series of bimodal and trimodal AP/HTPB propellants. The burning rate predictions as well as pressure exponent and temperature sensitivity results are presented.

Rotational relaxation for a rough particle model

Angular momentum and rotational kinetic energy relaxation for a simple model due to Widom is studied. Averages and correlation functions decay strictly exponentially, while distributions can exhibit two peak structures absent in approximate treatments but observed experimentally.