Abstract: A security system of the bridge circuit type has in one of its arms a conducting element whose impedance is to be monitored and in its other arms reference and/or compensating elements, for detecting an unbalance of the bridge resulting from a sudden change in the impedance of the conducting element. At least one of the reference elements has a variable impedance. The phase shift of the signal obtained at the output of the bridge circuit is detected, due to the drift of the bridge circuit, with respect to the A.C. supply frequency. The detection signal is then used for compensating the drift by acting on the reference element having a variable impedance in order to bring the bridge circuit back to balanced condition.

Abstract: Descaling apparatus for steel rod wherein the rod is first bent by two sets of rollers oriented perpendicular to each other to initially dislodge the scale from the surface of the rod. The scale is collected in a hopper then conveyed to a tank where it is mixed with and suspended in water. The scale and water mixture is pumped out of the tank then projected against the surface of the wire as it passes through a descaling chamber by a series of nozzles staggered angularly and longitudinally through the chamber. The mixture following the descaling operation is collected and conveyed to a hydrocyclone and separator which recycles the larger scale particles and water while disposing of the finer scale particles which are too small for use in the descaling operation.

Abstract: Descaling of metal wire by bending is followed by projection of the scale from the wire. The scale, projected by nozzles in a descaling device, is a mixture of new scale coming directly from the wire undergoing the bendings and scale recycled several times by a recycle feedback path. This application is applicable to the treatment of steel wire known as "rod" coming from hot rolling.

Abstract: A method of producing a tubular lattice reinforced concrete pipe having a socket at one end including first providing a flat rectangular lattice of longitudinal and transverse members connected at their crossing points, and then forming the flat lattice into a tube; the transverse members are highly ductile and stretchable adjacent one end and this end is expanded to form the socket portion of the reinforcement.