Abstract: A method for obtaining a model of a surface including the steps of obtaining measurements of geometrical data concerning specific points on the surface, making a grid of the surface, with the grid passing through said points, memorizing, at an address which is specific to each node of the grid, the coordinates of the node, the number of satellites of the node, information for access to the addresses of said satellites and thereafter to information which relates to them, and geometrical data which may be associated with said node; for each node, defining a local roughness index obtained from a weighted sum of the current coordinates of the node and its satellites, defining the sum of an overall roughness index representing the sum of all the local roughness indices, and of an overall index of the infringement of said geometrical data, iteratively adjusting the coordinates of indefinite nodes, by using at each adjustment the sum of a weighted combination of current node neighbor coordinates and of a combination

Abstract: The invention relates to recovery of an aprotic polar solvent from a saline aqueous solution of this solvent, by a process which consists in desalting the said solution by electrodialysis then in distilling the desalted solution.To avoid precipitation of metal hydroxides during the electrodialysis, the brine is kept at an acidic pH.

Abstract: An enclosure 1 has a measurably variable volume chamber 2, a control for controlling the temperature of the fluid contained therein and apparatus for measuring the pressure of the fluid. The chamber is selectively connectable, on the one hand, to a filling device 6, for introducing the sample, and on the other hand to a fluid extraction apparatus 7, 8. The enclosure 1 is selectively connectable to a tubular loop 9 having a circulation pump 10 and apparatus 11 for measuring the density of the sample of circulating fluid. By varying the volume of chamber 2, the thermodynamic characteristics of monophase and diphase fluids can be accurately determined. The apparatus is especially useful for the study of fluid of hydrocarbon deposits.

Abstract: New application of microemulsions as buffers between the slurry and the cement in the cementation of oil wells. The microemulsions contain an amphoteric surfactant selected from the group of alkyl dimethyl betaines.

Abstract: A method of making homogeneous particulate compositions for use as heat-fusible adhesives which include a thermoplastic polymer and a gluing agent. The method includes the steps of preparing a mixture of water, the gluing agent, and a suspension agent, heating the mixture to the fusing temperature of the polymer, stirring in such a way that the molten mass is broken up into particles of about 0.005 to about 5 mm, cooling while stirring, and separating the particles from the aqueous phase.