Abstract: A "digital" valve comprises a plurality of shutters (46) connected in parallel between an inlet duct (2) and an outlet duct (42) of the digital valve, with each shutter (46) being constituted by an elementary spherical plug valve (50) capable of transmitting an individual flow rate. These shutters are distributed angularly around the axis of the digital valve and each of them is incorporated in a module (24) received in a standard seating (14, 18), thereby making it easy to remove any of the modules. The invention is particularly applicable to rapidly changing over between different flow rates of a liquid or a gas under the control of a digital electronic system (70).

Abstract: This casing voussoir is of the type comprising a metallic frame 1, 2, 3.sup.a, 3.sup.b, 9 and a mass 12 of concrete or other like material strong in compression and anchored to that frame, the assembly having the shape of a cylindrical ring sector, characterized in that the frame 1, 2, 3.sup.a, 3.sup.b, 9 comprises two plates 1, 2, arranged along radial faces of the voussoir and interconnected by bars 3.sup.a, 3.sup.b, constituted by distinct parts of these plates 1, 2 and fixed to these latter by means of a filler material 8. A particular applications can be found for this voussoir in the lining of tunnels or similar underground works.