Abstract: In one aspect, a protective headwear is provided and includes a headgear, an outer shell, a duct and a manifold. The headgear is configured to engage a wearer's head and at least partially support the protective headwear on a wearer's head. The headgear includes a front, a rear opposite the front, a right side, and a left side opposite the right side. The outer shell is coupled to the headgear at a coupling location and includes a shield positioned to the front of the headgear. The duct is at least partially coupled to and at least partially positioned in an interior of the outer shell. The duct is located below the coupling location.

Abstract: A selectively densified composite sealant includes a porous layer having a first major surface and an opposing second major surface. The porous layer is formed of a porous membrane and having alternating first densified portions and second undensified portions that form respective valleys and peaks in the porous layer. An elastomeric layer is disposed on the first major planar surface of the porous layer and is formed of an elastomeric material that fills the valleys between the undensified portions.

Abstract: A high power, low frequency flextensional transducer (50) for underwater use comprises a number of spaced piezo-electric element stacks (53) between opposed inserts (51, 52). A Kevlar (registered trademark) compression band (54) is wound around the stacks and inserts and then partly elliptical plaster formers (56) are attached. A filament wound elliptical GRP flexural shell (57) is then wound around the assembly while controlling the tension so as to provide the required pre-stress on the piezo-electric stacks (53) when cured. After curing the plaster formers (56) are removed. End-plates (16) are attached to the elliptical shell (57) to complete the transducer; the shell (11) having a compression bonded layer (61) of neoprene applied, including a peripheral serrated lip seal (62) to seal against the end-plate (16) while permitting flexing of the shell. A device to provide wide bandwidth performance is also disclosed.

Abstract: A high power, low frequency flextensional transducer for underwater use comprises a number of spaced piezo-electric element stacks between opposed inserts. The stacks are placed on the plane through the major axis of an elliptical flexural shell and the inserts are shaped to conform with the elliptical shape. The stacks are assembled with first tapered supports and complementary tapered slides are wedged between the shell inserts and the tapered supports until a required pre-stress is exerted by the shell on the piezo-electric stacks. End-plates are attached to the elliptical shell to complete the transducer; the shell having a compression bonded layer of neoprene applied, including a peripheral serrated lip seal to seal against the end-plate while permitting flexing of the shell. A means to provide wide band-width performance is also disclosed. To extend the range of operational depths the cavity within the transducer is filled with a gas whose vapor pressure can be temperature-controlled.

Abstract: A high power, low frequency flextensional transducer for underwater use comprises a number of spaced piezo-electric element stacks between opposed inserts. The stacks are placed on the plane through the major axis of an elliptical flexural shell and the inserts are shaped to conform with the elliptical shape. The stacks are assembled with first tapered supports and complementary tapered slides are wedged between the shell inserts and the tapered supports until a required pre-stress is exerted by the shell on the piezo-electrical stacks. End-plates are attached to the elliptical shell to complete the transducer; the shell having a compression bonded layer of neoprene applied, including a peripheral serrated lip seal to seal against the end-plate while permitting flexing of the shell. A means to provide wide band-width performance is also disclosed. To extend the range of operational depths the cavity within the transducer is filled with a gas whose vapour pressure can be temperature-controlled.