Some investigators have proposed models for large-scale Discrete Element Method (DEM) simulations since the numder of particles is restricted by the limit of computer memories In these models the particle-to-particle contact force was not evaluated accurately. This is due to the fact that the models were developed for fluidized beds where the fluid drag force is dominant. In the present study, Advanced Representative Particle Model (ARPM) is developed to evaluate the contact force accurately in the large-scale DEM simulations. In the ARPM, the original small-size particles are represented by a large-size ARPM particle. The translational and rotational energies are the same for the ARPM particles and the original small-size particles in the interaction. In this study, the ARPM is verfied by numerical examplas. It is clarified that the behavior of the original small-size particles is successfully simulated by using the large-size ARPM particles.

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This paper presents the ralations between the collection efficiency and the flow characteristics in a cylindrical cyclone separator. The experiments on collecting particles and the measurements of velocity in the cyclone were carried out for various sizes of an air hole of the separating plate. As a result, it was clarified that the collection efficiency of cylindrical cyclone is influenced by the air hole size of separating plate. In the case of an air hole size which gives the maximum collection efficiency, the upward flow velocity in the center region of cyclone becomes high and the fluctuation in the flow intensity becomes small. Furthermore, we studied the frequency components of velocity fluctuation by the FFT analysis and found that the low-frequency components decline at the maximum collection efficiency.

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Polyvinyl chloride (PVC) powder was ground with NaOH pellets in air by using a planetary ball mill to cause mechanochemical (MC) dechlorination reaction and the product was subjected to thermogravimetric analysis to investigate its thermal decomposition performance. The dehydrochlorination and thermal decomposition temperatures of the product were lowered by the mechanochemical (MC) treatment.The total electric power consumption (EPC) for the dechlorination and thermal decomposition of product was obtained by summing up the values of EPC for the MC dechlorination reaction and thermal decomposition. The total EPC was reduced by the MC treatment and the MC treatment of PVC sample with NaOH lowered the EPC for the thermal decomposition. The effective MC treatment conditions which minimizes the EPC for the sample mixture in the present work are 12 hours grinding at 600rpm with Na/Cl=1 using a planetary ball mill.

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Ground liquefaction has been paid a great deal of attention to since the Niigata Earthquake in 1964. The event accelerated the research on ground liquefaction, and the outcomes of the researches have been incorporated in earthquake-proof design manuals and the codes for engineering structures. However, the phenomena are not yet well understood, and severe damage have been reported by soil liquefaction in recent earthquakes. In this paper, liquefaction phenomenon is explained in a simple manner to help in the understanding together with the latest analytical methods.

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