Abstract: A method for analysing a dynamic scene partitioned into cells which involves determining a probability of occupancy of a cell and a probability or probabilities of movement of the cell by solving the equation P(OV|ZC)=?AO?1 V-1P(CAOO?1VV?1Z)/?AOO?1VV?1P(CAOO?VV?1Z) comprising the determination of the speeds and positions of dummy particles in the grid depending on those determined at the (k?1)th iteration and the probability P(VFV-1); the determination of the particles located in each cell depending on the determined positions, and the solving of the equation, for a cell, is split into the solving of a static part corresponding to P(O=empty, V=O|ZC) and P(O=occupied, V=O|ZC) and the solving of a dynamic part corresponding to P(O=occ, V=vkl,|ZC), i=32 1 to nk, in which nk is the number of particles determined in cell C for the kth iteration.

Abstract: In a very high voltage electrostatic generator, the electrostatic charges are conveyed by a belt which rotates in a closed circuit between the earthed zone and the high voltage zone of the generator. According to the invention, a structure (6) offering a flat surface (60) to the belt section (5) is provided opposite the belt section (5). A gap (50) containing sulphur hexafluoride is thus formed between the structure (6) and the belt section (5). The structure (6) is made of a dielectric material (61) such as an epoxy resin which preferably contains conductive elements (62). The structure (6) is in addition traversed by tubules (63) opening on to the surface (60) so as to enable a cushion of sulphur hexafluoride to be formed in the space (50). This arrangement can operate under higher electric charge outputs than has hitherto been possible.