Abstract: Two face-to-face metal sheets, one or each of which is superplastically deformable, are subjected to a bonding and pressure deformation process in which the sheets are bonded together at a series of spaced positions thereon and the areas of the or each superplastically deformable sheet between these positions move away from the other sheet so that there is formed a series of cavities between the sheets, the sides of neighboring cavities being substantially adjacent to one another over substantial parts of their areas. These sides of the cavities, which are preferably substantially rectangular may come directly into contact with one another and be diffusion bonded together either directly or via reinforcing members.

Abstract: Continuity detector apparatus is coupled into duplicate conductors connected in parallel between each rail of a track section and an energy source or occupancy receiver of an associated track circuit to detect and register a fault in either parallel conductor and to indicate need for corrective action to restore the operational security provided by the duplicate circuit paths. In one form, each detector is a two-winding relay with one winding inserted in series in each of the duplicate circuit paths so poled that equal track current flows in opposite directions in the winding, when both conductors are unbroken to hold the relay released. Any interruption of either parallel conductor causes the relay to pick up to register the fault and transmit a corresponding indication. In a second form, a different transformer winding is connected with each conductor.

Abstract: This disclosure is concerned with reducing blade-generated cavitation and accompanying noise in systems such as marine ducted reversible thrusters and the like, by novel techniques including a skew-forward blade configuration at the outer radii and particular blade thickness/chord length ratios associated therewith.

Abstract: The molecular weight of a liquid, linear dead polymer terminated with an alpha-alkoxyalkyl ether group, is increased by heating with an acid catalyst in the absence of a solvent.