Abstract: A face mask is provided in two parts. One part is an adhesive ring that is secured around the nose and mouth of the user. The other part is a transparent canopy with a gas port that is a removable clip fit with the ring. When ventilation is not required, the canopy is removed, leaving the ring in position. The canopy can be clipped back onto the ring when ventilation is required.

Abstract: A marine radar antenna has a single dielectric plate mounted in front of the waveguide polarization grid between two horn plates. A strip of dielectric material is secured to the upper and lower surfaces of the plate to form a forwardly and rearwardly facing step on each surface. The steps are located forwardly of the ends of the horn plates and are positioned to produce reflections substantially 180° out of phase with extraneous energy within the antenna. The dielectric plate is supported by a foamed plastics material within an outer radome.

Abstract: An electrical socket has resilient wires extending together in a hyperboloid arrangement between retaining rings at opposite ends of the socket to which they are welded. The wires are grouped together in pairs and the pairs are spaced from one another around the socket. The socket is assembled by loading pairs of wires into respective slots extending along a mandrel.

Abstract: A laryngeal mask airway has a main tubular shaft (1) with a channel (2) of part circular section opening along its external surface. A mask portion (5) is attached to the patient end of the shaft, including a mount (50) and a cuff (60) attached to the mount. A channel (55) extends along the mount (50) from the channel (2) in the shaft (1) to the cuff (60). A small-diameter tube (70) opens at one end into the cuff (60) and extends along the channels (55 and 2) in the mount (50) and in the shaft (1). The channel (2) in the shaft (1) mechanically retains the small-diameter tube (70), the tube extending out of the channel through one of several notches (20) spaced along the channel. The tube (70) can be peeled away from the shaft (1) to extend out of one of the other notches (20), so that the shaft can be cut shorter.

Abstract: A tracheostomy tube has a sealing cuff inflated by an inflation tube extending in a channel along one side of the tracheostomy tube. A suction tube extends in a channel along the opposite side of the tracheostomy tube. The suction tube extends to the upper end of the sealing cuff and opens into a recess on the outside of the tracheostomy tube through a side opening oriented at right angles to the radius of the tracheostomy tube. The recess extends around about 90° of the tube towards its outer curve so that secretions collecting in this region can be removed.

Abstract: A microwave antenna has a rectangular section waveguide with two narrow walls and and two broad walls. Towards one end, the waveguide is coupled with a microwave transition by which a coaxial connector can be coupled to the waveguide. The transition has a conductor extending through a narrow wall and connected internally with a transition plate. The transition plate extends longitudinally, centrally along the waveguide and is stepped to provide a quarter wave section.

Abstract: A power amplifier has a pair of FETs of opposite kinds connected together to form a source/drain circuit connected with an output. A second pair of high speed transistors is connected to the input and forms a collector/emitter circuit connected to the gates of the FETs. Capacitors are connected across the second pair of transistors and the pair of FETs respectively. Opposing current sources connect with the bases of the second pair of transistors via a resistor divider.

Abstract: An avionics housing has electrical connectors mounted centrally on a front face. Transient voltage suppressors are located in an array of holes in a metal plate to each side of the connectors, beneath removable panels so that they are accessible on the front face after removal of the panels. The suppressors extend through the plate to connect with circuit boards on the opposite side that have tracks connecting with the connectors. A filter module is secured behind the circuit boards and supports filters that connect with connections on the boards. A rear connection assembly carries connectors on its rear surface by which connection is made to circuits within the unit. Flexi-rigid circuits interconnect the rear connectors with socket array boards on the front of the rear connection assembly and these, in turn, connect with contacts on the filter module.

Abstract: A capacitance fuel-gauging system has a capacitive probe and a reference capacitor charged in opposite senses from respective dc voltage sources via switches operated in antiphase. Two further switches alternately discharge the capacitors to a 0 volts rail. The outputs of the probe and the reference capacitor are connected to a summing node, which is connected to an amplifier via a pair of switches operated in antiphase to rectify the output. The amplifier connects to a processor, which controls the relative outputs of the voltage sources and provides an output indicating the value of the probe.

Abstract: A laryngeal mask assembly has a tube with a mask at one end defining a cavity surrounded by a sealing cuff. A blocker is operable to prevent entry of the epiglottis into the cavity during insertion of the assembly but does not hinder gas passage along the assembly after insertion. The blocker may be a ballon that is inflated during insertion and is then deflated. Alternatively, the blocker may be a web attached to the patient end of the assembly by a rupturable joint. In another arrangement the blocker is an insert with an end that expands to fill the cavity but that is compressible to allow the insert to be pulled out from the machine end of the assembly.

Abstract: A percutaneous tracheostomy assembly has a hollow needle carrying a cannula with a hub at its rear end abutting a hub on the needle. A channel-shape stop is clipped onto the cannula and needle so that its rear end abuts the hub of the cannula. The stop has a laterally-extending flange at its forward end. The length of the stop is such that the tip of the needle and the forward end of the cannula are positioned within the trachea when the flange abuts the skin of the neck, without the risk of the needle contacting the posterior wall of the trachea.

Abstract: An aircraft fuel-gauging system has multiple ultrasonic gauging probes providing fuel height outputs at several locations within a tank. The output of an inertial sensor is used to compute the attitude of the fuel surface with respect to the tank. The system uses the attitude information to determine whether outputs from a group of two or more probes are compatible with one another. Where a probe is identified as having an output incompatible with the fuel surface attitude and the outputs of other probes its output is excluded from the computation of the fuel quantity.

Abstract: A laryngeal mask has a blocker at its patient end to prevent entry of the epiglottis during insertion. The blocker has a tear-drop shape plate retained around its edge in grooves in the mask and attached to a flexible strip extending along the outside of the assembly.

Abstract: A multi-plate dual flow path heat exchanger includes a plurality of stacked plates 70 each having a central section 71 provided with a number of longitudinal channels 72 separated by upstanding zig-zag walls 75, the channels 72 being provided on their floors 72A with ridges 74, the floors and the ridges being of undulating form along the flow paths. Shallow ribs 75 extend laterally across the flow paths and in combination with the undulations assist in disruption of boundary layer flow.

Abstract: Sound attenuating ducting has an inner, helical wire supporting an inner and outer layer formed by strips of a foamed thermoplastic rubber material. Axial and helical reinforcing yarns extend along the ducting between the layers. The two strips are applied from extruders, the extrusion rate of the inner strip being set to be less than that of the outer strip so that the inner strip is stretched to produce a more porous structure than in the outer strip. In this way, the inner layer is efficient in absorbing orifice noise within the ducting and the outer layer contains radiated noise.

Abstract: An epidural catheter with a soft tip is formed by extruding a two-layer tube where the inner layer is stiffer than the outer layer. The inner layer is then removed, such as by machining, from a short length at the tip, which is subsequently end-formed closed and a side opening cut into it.

Abstract: An aircraft fuel-gauging system has flowmeters at the inlet and outlet of a fuel tank. The output of the flowmeters is used to compute the height and volume either of a localised elevated region above the inlet, where fuel flows into the tank, or of a localised depressed region above the outlet where fuel flows out of the tank. Where the gauging probes are located away from the region of the inlet or outlet, the volume derived from the probes is corrected by adding the volume of the elevated region or by subtracting the volume of the depressed region. Where the gauging probes are located in the region of the inlet or outlet, the height output of the probe is corrected either by subtracting the height of the elevated region or by adding the height of the depressed region. The volume is computed from these corrected heights and further corrected by adding the volume of the elevated region or by subtracting the volume of the depressed region.

Abstract: Sound attenuating ducting has an inner, helical wire supporting an inner and outer layer formed by strips of a foamed thermoplastic rubber material. Axial and helical reinforcing yams extend along the ducting between the layers. The two strips are applied from extruders, the extrusion rate of the inner strip being set to be less than that of the outer strip so that the inner strip is stretched to produce a more porous structure than in the outer strip. In this way, the inner layer is efficient in absorbing orifice noise within the ducting and the outer layer contains radiated noise.

Abstract: The mask of a laryngeal mask assembly has a mount and an integral cuff at the patient end of a tube. The mount is of a thermoplastic material and the cuff is made by blow moulding from the material of the mount. A separate retaining plate seals an edge of the cuff with the mount and traps an inflation tube extending from the cuff to the inflation line of the tube.