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Many plastic balls, made from PolyOxyMethylene (POM) and of three different diameters 2, 3 and 4 mm, were used to observe the formation and stability of the structure in ball beds when, after pouring into a plexiglass cylinder, they were subjected to long-term vertical vibrations with frequency 100 Hz. The vibration table Vibrax (Renfert GmbH, Germany), used in the experiment and shown in Fig. 1, can function in two modes: sinusoidal (s) and nonsinusoidal (ns). The vibration table can act at four power levels of the vibrations, selected by an operator using the right knob of the table (see Fig. 1). In the presented series of 43 vibration experiments, always the highest power level was used.
Locations of surface balls on all sides of a vibrated cylindrical bed were simultaneously recorded on one video frame thanks to the use of two perpendicular mirrors (see Fig. 1), which enables observation of four images: one of the real cylinder and three of its mirror reflections. An explanation of the scene, as seen by the recording camera, is given in the scheme in Fig. 2. Video names were given in a standard form to inform the user about the most important parameters (more in README.txt).
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