Effects of Material Properties on Granular Flow in a Silo Using DEM Simulation

In order to test the effect of material properties on flowability of particulate materials, discharge procedures of spherical particles within a flat-bottomed model silo with three sets of material properties, i.e., soft and hard without adhesion and adhesive hard, were simulated using the Discrete Element Method. For each system, three particles on the center line were selected and their instant vertical velocity components were traced. In addition, both discharge and the rate were recorded throughout the procedure. The predicted results show that, for both the systems without adhesion, though the soft has a material modulus only 1/1000 of the hard, there are no significant differences in f low pattern and discharge rate. This suggests that a soft system can be used to predict the behavior of a hard one to save CPU time in a gravity-driven granular flow. On the other hand, comparison between both hard systems shows that adhesion can significantly reduce the flowability in granular flow. By analyzing the velocity plot for the traced particles, free fall was clearly detected above the decompression zone, indicating the motion of a particle in a granular flow can be resolved as free fall together with the movement due to particle collision. In addition, select dynamic behavior related to the kinetic fluctuations affecting flow was observed.

discrete element method silo granule flow particulate material     

Meta-analysis of assessment center validity.

Meta-analysis (Hunter, Schmidt, & Jackson, 1982) of 50 assessment center studies containing 107 validity coefficients revealed a corrected mean and variance of .37 and .017, respectively. Validities were sorted into five categories of criteria and four categories of assessment purpose. Higher validities were found in studies in which potential ratings were the criterion, and lower validities were found in promotion studies. Sufficient variance remained after correcting for artifacts to justify searching for moderators. Validities were higher when the percentage of female assessees was high, when several evaluation devices were used, when assessors were psychologists rather than managers, when peer evaluation was used, and when the study was methodologically sound. Age of assessees, whether feedback was given, days of assessor training, days of observation, percentages of minority assessees, and criterion contamination did not moderate assessment center validities. The findings suggest that assessment centers show both validity generalization and situational specificity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of dark-rearing, strobe-rearing and acute visual cortex removal on the visual responses in the superficial superior colliculus of the guinea-pig

The interaction of zinc and vitamin A in rats receiving a regional diet of Manaus, supplemented with vitamin A, zinc and zinc and vitamin A was studied. The regional diet was elaborated according to data of Shrimpton and Giugliano (6), for families receiving less than two minimum salaries. The biological test to study the interaction was based on the depletion of zinc and vitamin A in rats in the period of lactation, and a period of repletion where supplements of zinc (0.82 mg%) and vitamin A (94.2 micrograms %) were given, either separately or together, according to the recommendations of the Committee on Laboratory Animal Diets (7). From the results, it was concluded that there was an interaction of these nutrients in terms of mobilization of hepatic vitamin A. Although the regional diet of Manaus did not meet the zinc RDA, the amount present was enough to utilize the available vitamin A. Although the amount of zinc present in the diet, as determined by parameters of bioavilability, such as growth, concentration in organs and zinc-dependent enzymes, was adequately used by the animals, probably due to promoting factors in the diet. The Manaus regional diet needs to be supplemented with vitamin A in order to maintain the hepatic reserves, and with zinc, to maintain the normal levels of vitamin A in plasma.     

Two-phase micropipeline control wrapper with early evaluation

A two-phase control wrapper for a micropipeline is presented. The wrapper is implemented in an Artisan 0.13/spl mu/ standard cell library that has not been augmented with any special cells for asynchronous design. The wrapper supports early evaluation allowing the output to be updated after a subset of the inputs have arrived, thus improving the throughput of the micropipeline.     

Central venous line sepsis in the intensive care unit. A study comparing antibiotic coated catheters with plain catheters

A randomized controlled clinical trial was undertaken to evaluate the efficacy of antibiotic bonded lines in the reduction of central venous catheter infection. One hundred and seventy-six plain and bonded catheters were inserted into one hundred and ten patients in an intensive care unit, many of whom were admitted with evidence of sepsis. The catheters used in the study group, which had been pre-treated by the manufacturers with the cationic surfactant tridodecylmethylammonium chloride, were bonded with vancomycin 1 g made up in 10 ml of water immediately prior to insertion. The catheters used in the control group were neither pre-treated nor bonded with vancomycin. Eighty percent of control group catheters were infected compared with 62% of study catheters (p = 0.01). The most common organism isolated was coagulase negative staphylococcus. We conclude that antibiotic bonding can reduce central venous catheter infection even in a patient population with a high incidence of sepsis.     

Independently addressable VCSEL arrays on 3-μm pitch

We present an exceedingly dense linear vertical-cavity surface-emitting laser (VCSEL) array with independently addressable elements on a staggered 3-μm pitch. Our devices utilize an all-epitaxial structure and operate at a wavelength of 813 mm with threshold currents below 400 μA. The high-packing density is enabled by combining transparent contact technology with a planar laterally oxidized device architecture. The array exhibits low interelement thermal crosstalk and has electrical resistances of 3 MΩ between adjacent array elements