Particle Separation Efficiency Research Articles

Mechanisms of seed harvest by heteromyid rodents: soil texture effects on harvest rate and seed size selection.

Several lines of evidence show that soil texture plays an important role in the distribution of desert-dwelling heteromyid rodents. This is not surprising, since texture influences the energetic cost of digging burrows and of scratching at the soil surface to harvest buried seeds. Texture also may influence the efficiency with which seeds can be separated from the soil particles with which they are mixed. To explore mechanisms of "particle separation" by foraging heteromyids we measured seed harvest rates and size selection in the laboratory for a variety of seed sizes and soil textures. Harvest rate declined with increasing soil coarseness, and the preference for seeds of intermediate size that was apparent in fine soil disappeared when seeds were mixed with soil slightly coarser than the preferred seed size. In addition, there was evidence that particle separation efficiency is sensitive to the relative sizes of seeds and soil. A discontinity in the function relating harvest rate to soil texture occurred at finer soil textures for small seeds than for large seeds, suggesting that harvest techniques change once soil particle diameter equals or exceeds that of seeds. These results are consistent with the hypothesis that heteromyids use a combination of gravity-and rake-sorting mechanisms for particle separation.

Separation of Alfalfa Silage Into Stem and Leaf Fractions in a Horizontal Airstream

ABSTRACT Aerodynamic drag coefficient was used as the differentiating characteristic in the separation of alfalfa haylage into leaf and stem fractions in a horizontal wind tunnel. The effects of air velocity, moisture content, feed rate, and air stream height on particle distribution and separation efficiency were investigated. To evaluate the separator a protein improvement index and separation efficiency were calculated. Results indicated that both increased airstream height and air velocities (up to 8 m/s) improved separation efficiency. An increase in either moisture content or feed rate resulted in a decrease in separation efficiency. Regression equations were developed to estimate protein improvement and separation efficiency as functions of airstream velocity, moisture content, and feed rate.

Effects of a high-velocity jet on fundamental particle-separation characteristics

The high velocity jet region of a jetted fluidized bed plays an important role in momentum, mass, and heat transfer in the bed. A two-dimensional, fluidized-bed cold model equipped with a high-velocity jet was constructed to study the role of this high-velocity region. Glass beads were used to simulate ash agglomerates, and millet and catalyst powder were used to simulate coal and char, respectively. The effect on particle separation of various operating parameters including jet geometry, jet velocity, and particle size and density was studied. From these experiments, some important information on particle separation was obtained. An optimal, jet-zone, geometric configuration was identified for efficient particle separation. A graphical representation of the particle-separation process for heterogeneous solids was developed. Also, empirical equations were developed to calculate initial-separation velocity and critical-separation velocity.

Effect of diet on composition of cecal contents and on excretion and composition of soft and hard feces of rabbits.

A total of 260 New Zealand White growing rabbits were used to study the effect of diet on chemical composition of cecal contents and on production and composition of soft and hard feces. Eight diets varying in their acid detergent fiber (9.8% to 32.7%) and starch (13% to 30%) levels were evaluated. The diet affected (P less than .01) all the variables studied, except dry matter (DM) and molar proportions of volatile fatty acids on cecal contents. An increase of dietary crude fiber increased crude fiber level in cecal contents (from 11.58% to 26.53%). However, a relatively lower proportion of fibrous material was found in the cecal contents when rabbits were fed the more fibrous diets. This suggests that dietary fiber has a direct influence on the efficiency of particle separation in the digestive tract. Crude protein and volatile fatty acid concentrations of cecal contents decreased (from 30.14% to 19.65% and from 47.8 to 36.7 mmol/liter, respectively) when dietary crude fiber increased. This could be related to availability of energy to cecal microorganisms. Ammonia concentration of cecal contents was not affected by dietary crude fiber. Daily production of soft feces varied from 14.98 to 29.59 g DM/d, and the contribution of soft feces to total DM and to crude protein intake ranged from 10.6% to 15.0% and from 12.8% to 20.5%, respectively; these values were the smallest and the largest for the least and the most fibrous diets, respectively. From this study we conclude that dietary fiber has a major effect on the digestive processes in the rabbit and that dietary starch level has no influence on any of the variables studied.

Similarity solutions for flow in hydrocyclones

Analytical and numerical solutions of similarity form are obtained for (assumed) inviscid flow in the generating plane of an axi-symmetric conical hydrocyclone below the level of the vortex finder. Results are compared with those based on corresponding approximate solutions derived using the methods of Bloor and Ingham, and differences from the original Bloor and Ingham solution are highlighted. Solutions are found which, if realised physically, would lead to greater separation efficiency of particles with density greater than the fluid. Such solutions are characterised by vertical velocity profiles at a given height which are flatter, and inward radial velocities which are smaller, in a region away from the cyclone wall and the axis of symmetry. However, entry conditions under which these solutions can occur are not known.

Pressure Dependence of the Relativistic Rise in Neon and Highest Attainable Ionization Sampling Resolution in Neon, Argon, Ethylene and Propane

A full-scale detector segment with 128 samples of 2 cm and a 50 cm drift space was used to measure precisely the relativistic rise of ionization from 5 to 70 GeV/c in Ne at 1, 2 and 4 atm. The pressure dependence of dE/dx resolution and of particle separation efficiency was determined at 15 GeV/c in several Ne/CnHm mixtures, in Ar/CH4, pure C2H4 and pure C3H8. The results are used for optimization of parameters of a compact colliding beam detector suitable for particle identification up to the 30-50 GeV/c momentum range. The ?/K/p separation is found to be better in Ne, but extends to higher momenta in Ar. Ar is more efficient for e/? separation. The gain in resolution at higher pressures is to certain extent compensated by reduction of the relativistic rise slope, so that the separation efficiency is reduced when the detector dimensions are scaled down with pressure. At 4-5 atm. we obtained slightly better resolution than the 6.0% FWHM (? = 2.5%) record performance of the EPI. In pure C3H8 a resolution below ? = 2.0% was reached. Measurements of drift velocities in various Ne mixtures are presented, showing saturated behaviour already at low E/p values.

Longitudinal Drift and Fine dE/dx Sampling in Various Gas Mixtures

Results of measurements realized at 15 GeV/c in a tagged e/?/p beam are presented. A longitudinal drift detector of 88 cm total length consisting of 16 stages of 4.7 cm drift each was used. Fast shaped signals from the detector were processed in a set of Flash ADC's with 25 ns sampling interval, corresponding to 0.3 - 2.6 mm distance in the drift space. Resolution and particle separation efficiency obtained in mixtures of Ne + 10% C3H8, Ar + 5% C3H8, Ar + 20% CO2, C3H8 + 20% C2H6 and in pure CH4 are compared to the performance of a classical method of charge integration over large samples.

磁性流体による比重選別 (第2報)

Two ferrite permanent magnets fixed on an iron yoke were arranged with suitable distance and angle. A nonmagnetic body placed in a magnetic fluid between these magnets receives a magnetic levitation force towards a minimum point of magnetic field. Thus the magnetic fluid could be regarded as dense medium suspension of high specific gravity.We reported about the separation of glass and porcelain in the first paper “Sink and Float Separation with Magnetic Fluid”. However, ceramic particles smaller than 5mm in diameter couldn't be separated satisfactory. Here, the relation between particle size and separation efficiency was investigated. Sphalerite, Pyrite and Galena whose size was from 3 to 100 mesh were used. Specific gravities are about 4.5 and 7.5 respectively. A water-base magnetic fluid was used as a medium.When put into this fluid, the mixture of those nonmagnetic minerals separated, except for particles smaller than a certain size. It was found that the lowest limit of the separation size depended upon the difference of specific gravity of them. And the smaller the difference was, the larger the limit size was. The principal reason for nonseparation of fine particles is that each nonmagnetic particle in the magnetic fluid under a magnetic field adheres to each other in the direction of the line of magnetic force. However, they repulse each other when positioned along the vertical direction of the line of magnetic force. In order to use this repulse force, we therefore constructed trial equipment to separate adhered particles by turning the cylinder in which the particles were placed in the magnetic fluid. As a result, we were able to separate the major portions of Pyrite and Sphalerite particles larger than 100 mesh size.

Separation of particles according to shape

Vibration sorting is a common means in separating non-spherical particles from spherical particles. In this paper, the discrete element method (DEM) is applied to simulate the behavior of spherical particles and non-spherical particles motion on an inclined vibrating plate (IVP), and the influence of different operating parameters on the separation performance of the mixed particles is investigated. In the DEM simulations, both the spherical and non-spherical particles are modeled by super-ellipsoids. The simulation results show that the optimal vibration amplitude and frequency exist for the high separation efficiency of the mixed particles. The separation efficiency can also be enhanced by properly increasing the friction coefficient or decreasing the restitution coefficient between particles and plate. It is easier to separate the non-spherical particles from the spherical particles by diminishing the sphericity of particles. Besides, as long as the inclination angle of the plate is set at appropriate range and the feed rate of the mixed particles is moderate, the non-spherical particles can be separated effectively from the spherical particles. This research could be helpful for the understanding and optimal design of vibration sorting device.