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Volume 29, Issue 2
Displaying 1-9 of 9 articles from this issue
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Jun YOSHIDA1992 Volume 29 Issue 2 Pages 86-94
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSThe inside pressure of a silo, especially the dynamic pressure during discharge is a very important factor in its structural design. However, numerical simulations of this problem have seldom been performed because of its complicated behaviors. In this report, the distinct element method (DEM) which is suitable for discontinuous media is used for analysis of the static state of granular materials in silos, and the possibility of its use to analyze the silo problem is indicated. Also, the characteristic distribution of pressures on walls are studied using the DEM simulation, and the influence of friction coefficients and particle arrangement are examined. The result of this study is that the pressure distributions from the DEM simulation are similar to the theoretical or experimental ones. This result of static analysis is used for the initial condition of dynamic analysis, and it is expected to simulate the complicated behaviors of granular materials during discharge in silos.View full abstractDownload PDF (3155K) -
Akira SHIMIZU, Yu-Jun HAO, Hirofumi SASAKI1992 Volume 29 Issue 2 Pages 95-101
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSFor the solid state reaction proceeded by a unidirectional diffusing process, the growing rate of the product layer is estimated based on the assumption that the rate is determined by the formation of the solid solution followed by the product phase. The role of the diffusing component in the solid solution can be considered analogously to Hatta's theory quantitatively describing two processes of the diffusion and of the chemical reaction in the minute region of the reacting area.
The reaction rate of the V2O5-MoO3 diffusion couple is analyzed by the use of the present result. The growing rate of the V9Mo6O40 layer can be represented well by this model, and the calculated diffusivity of the MoO3 component in the V2O5ss layer is found to be 8.8×10-15m2s-1 at 600°C.View full abstractDownload PDF (1639K) -
Toyokazu YOKOYAMA, Teruo KUBOTA, Genji JIMBO1992 Volume 29 Issue 2 Pages 102-109
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSThe effects of mechanical grinding conditions on the limit of grinding of alumina powder in water was investigated using a planetary ball mill. The evaluation of ground particles was done based on the specific surface area by the BET method and by pore distribution with mercury porosimetry, as well as being based on particle size analysis by the laser scattering-diffraction method and by observation with a microscope.
Negative grinding phenomena were confirmed also in the wet grinding of alumina, and its grinding equilibrium size was well correlated with the maximum force exerting on a single ball when the product fineness was evaluated by the laser scattering-diffraction method. However, a decrease in the specific surface area by the BET method was not obtained, though it approached a certain value independent of the mechanical grinding conditions. It was found that the grinding equilibrium size was hardly influenced at all by the feed size, but it was influenced by the solid concentration to some extent.View full abstractDownload PDF (2618K) -
Shuji MATSUSAKA, Yasutaka NAKAMURA, Hiroaki MASUDA1992 Volume 29 Issue 2 Pages 110-115
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSParticle reentrainment from a fine powder layer was investigated both theoretically and experimentally by use of an accelerated air flow. Reentrainment fluxes and critical reentrainment velocities were calculated under several conditions by the previously reported reentrainment model. The model is based on the adhesive strength distribution of particles, the surface renewal of the powder layer, and the time dependent reentrainment rate.
It is found that the reentrainment flux increases with increasing average air velocity, and the reentrainment flux is approximately proportional to the air acceleration. It is also found that the critical reentrainment velocity decreases as the acceleration increases. This tendency becomes more prominent for smaller acceleration. These theoretically estimated phenomena are well supported by the experimental data on the reentrainment flux and critical reentrainment velocity.View full abstractDownload PDF (791K) -
Tatsuo TANAKA1992 Volume 29 Issue 2 Pages 116-117
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
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Mitsutaka KITAMURA1992 Volume 29 Issue 2 Pages 118-123
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
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Hiroshi IWANAMI1992 Volume 29 Issue 2 Pages 124-128
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
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Keijiro TERASHITA1992 Volume 29 Issue 2 Pages 139-142
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
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1992 Volume 29 Issue 2 Pages 143-146
Published: February 10, 1992
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (3605K)
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