A new method of representing non‐spherical, smooth‐surfaced, axi‐symmetrical particles in discrete element (DE) simulation using model particles comprising overlapping spheres of arbitrary size whose centres are fixed in position relative to each other along the major axis of symmetry of the particle is presented. Contact detection and calculation of force‐deformation and particle movement is achieved using standard DE techniques modified to integrate the behaviour of each element sphere with that of the multi‐element particle to which it belongs. The method enables the dynamic behaviour of particles of high aspect ratio and irregular curvature (in two dimensions) to be modelled. The use of spheres to represent a particle takes advantage of the computational speed and accuracy of contact detection for spheres, which should make the method comparable in computational efficiency to alternative schemes for representing non‐spherical particles.

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ZnO nanoparticles were synthesized by the sol-gel method. The nanoparticles were added to polyvinyl alcohol (PVA) biopolymer to compare the microstructural, mechanical, antibacterial and physical properties of bionanocomposite films reinforced with various loading contents (1, 3 and 5 wt %) and thicknesses (70, 100 and 130 μm). Results showed that with increasing ZnO content to 3 wt %, the tensile strength and Young's modulus increased by 64 and 72%, respectively. The least amount of water vapor permeability was also observed in the sample containing 5 wt % ZnO nanoparticles. Moreover, the antibacterial properties of the films improved with ZnO addition and increased by increasing nanoparticle content up to 5 wt %. However, the transparency of the PVA-based films decreased by ZnO addition.

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A b s t r a c t. Some moisture-dependent physical properties of Christmas Lima were investigated. Results of experiments on rewetted Christmas Lima bean seed showed increasing in length, width, thickness, geometric mean diameter, volume, sphericity, mass, 1 000 seeds mass, projected area and terminal velocity. A decreasing trend for bulk density and true density was observed. Both static and dynamic coefficients of friction increased as the moisture content increased. The highest static (0.59) and dynamic coefficients of friction (0.34) were found on the rubber surface. The average rupture force, rupture deformation and rupture energy were investigated under compression loading. These characteristics were determined as functions of moisture content, compression orientations and deformation rates. At all deformation rates, rupture deformation and rupture energy of the Christmas Lima bean generally increased with increase of moisture content. Moreover, rupture force decreased for compression along the X-and Y-axis.K e y w o r d s: Christmas Lima bean, moisture content, physical properties

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