Abstract: An aircraft fuel quantity gauging system has a number of probes within a tank to measure the height of fuel at different locations. Each probe includes a still well and an ultrasonic transducer mounted at the top and bottom of the still well. The lower transducer transmits pulses of acoustic energy upwardly through the fuel to its surface and measures the time of travel back of the reflected pulse back to the transducer. This is used to derive a first, bottom-up measure of fuel height. Similarly, the upper transducer transmits pulses down through air to the fuel surface to derive a second, top-down measurement. These are compared to check for correct operation of the probes.

Abstract: A syringe pump has a drive mechanism for moving the plunger of a syringe along a barrel. Ears at the rear of the barrel engage against a wall on the pump and an L shape clamp arm is urged against the ears by a spring. The clamp arm is mounted about an axis at right-angles to the syringe and is articulated at a point along its length. A lever having a flag at one end is pivoted about a horizontal axis by movement of the arm and moves relative to an optical sensor so that the output of the sensor indicates whether the syringe is correctly loaded in the pump. The clamp arm is rotated away from the barrel by the drive mechanism during loading of the syringe.

Abstract: A seal arrangement provides a seal between a bore and a rod movable in the bore with a gap formed between the bore and the rod. The seal arrangement includes a floating elastomeric sealing ring which is accommodated in a circumferential groove around the rod. The sealing ring sealingly engages the wall of the bore. An annular resilient biasing device is also accommodated in the groove. The biasing device acts between one wall of the groove and the sealing ring to urge the sealing ring against an opposing wall of the groove. In addition, the biasing device is configured to allow passage of fluid past the biasing device between a region of the groove disposed radially inwardly of the sealing ring and the gap between the rod and the bore on the side of the sealing ring opposite the opposing wall. The biasing device has, at least at some circumferential positions therearound, a cross-sectional profile that reduces in radial width towards one wall of the groove.

Abstract: A marine radar antenna has a single dielectric plate mounted in front of the waveguide polarisation 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: A syringe pump has a plunger head retainer with two retainer arms mounted on shafts extending parallel to the syringe axis. Each shaft carries a gear, which is engaged by common gear wheel mounted on a threaded shaft. Initially, the shaft is rotated to displaces the gear and hence the retainer arms axially forwardly, and thereafter swing the retainer arms outwardly to an open position. After the syringe has been loaded in the pump, the plunger head retainer is driven forwards until a pad coupled with a force sensor detects contact with the head. This causes the retainer arms to be swung in across the forward side of the plunger head and to be pulled rearwardly against the plunger head. The pump then reduces the force applied by the retainer arms to ensure that the force sensor can respond to force on the plunger during expulsion of liquid from the syringe.

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 aircraft ultrasonic fuel-gauging system has a processing unit that energizes probes and receives signals from transducers arising from energy reflected back from the fuel surface. In addition to determining the time between transmission of a signal from the transducer and reception of its reflection from the fuel surface, the processing unit also determines the time of reception of subsequent reflections caused by reflection back from the lower end of the probe. The processing unit determines whether the subsequent reflected signals are within predetermined limits of the time interval between transmission and reception of the first reflected signal in order to confirm the validity of the first signal. The processing unit also counts the number of subsequent reflected signals received within predetermined time intervals to assign a confidence level and this used to select between different incompatible signals, such as signals from that probe at different times or signals from different probes.

Abstract: An electron emitter, such as for a display, has a substrate and regions of n-type material and p-type material on the substrate arranged such that there is an interface junction between the regions exposed directly to vacuum for the liberation of electrons. The p-type region may be a thin layer on top of the n-type region or the two regions may be layers on adjacent parts of the substrate with adjacent edges forming the interface junction. Alternatively, there many be multiple interface junctions formed by p-type particles or by both p-type and n-type particles. The particles may be deposited on the substrate by an ink-jet printing technique. The p-type material is preferably diamond, which may be activated to exhibit negative electron affinity.

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 processing system has a processor with a memory map identifying locations in a memory where data are stored, data associated with an application being stored at the same location every time an application is run. The processor runs each application during specified processing time slots. A monitor contains information as to the memory locations associated with each application and the time slots during which each application should be run. The monitor also has a register containing a keyword, which is compared with a keyword supplied by the processor 1 when it switches between user mode and supervisory mode so that the monitor denies access to memory locations associated with the other mode.

Abstract: A cable clamp has two identical moulded components that can be clamped together about a cable. Each component has a yoke with a ratchet bar at one end and two short arms at its opposite end spaced by a gap and having ratchet teeth on their inner faces. The ratchet bars on each component extend in the gap between the arms on the other component and the cable extends through the aperture between the two yokes and between the two ratchet bars. The yokes can be squeezed together about the cable, causing the ratchet bars to slide over the engaging teeth, which prevents the two components being subsequently separated.

Abstract: A syringe pump has an arm swung against the barrel of the syringe. The arm is coupled to a strip mask having a row of transparent apertures of differing length. The mask extends above a CCD array of sensing elements and below a concave mirror, which produces a collimated beam of radiation on the mask from an LED. The length of sensing elements exposed to radiation through an aperture in the mask gives an approximate indication of barrel size; the position of an edge of the aperture gives an accurate indication. The pump compares the barrel size with information relating size to syringe type and produces an indication of syringe type on a display.

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 guide for an endotracheal tube has an outer sheath of a flexible plastics within which is embedded a bendable rod. The rod is of a metal, such as a copper-plated, zinc-iron alloy and is crimped with a series of indentations along opposite sides so as to give it a preferential plane of bending including the center lines of the indentations. The sheath is a hollow tube opening at both ends through hollow plugs.

Abstract: A hyperboloid electrical socket contact has a tubular ferrule with several oblique slots extend along its length. Resilient contact wires extend along the slots so that they project inwardly into the bore through the ferrule midway along their length to form a contact region for an inserted male pin. The ends of the wires are bent into locating notches in the ferrule where they are welded.

Abstract: Parallel cathode electrodes extend across the base plate of a display. Each electrode has teeth projecting from both sides, the teeth of adjacent electrodes being closely spaced from one another by a gap that is bridged by a dot of an electron emitter material. A glass screen spaced by a vacuum gap above the base plate carries transparent anode stripes extending transversely of the cathode electrodes and a fluorescent layer of colored phosphors on the anode stripes. A voltage applied between adjacent cathode electrodes and gates conduction via each electron emitter dot. A voltage applied to an anode stripe causes a part of the current from the emitter directly below the stripe to be directed towards the anode, thereby illuminating the phosphor pixel above the emitter.

Abstract: A heat-recovery unit includes an outer housing and a heat-recovery cell with two separate air passages therethrough opening on faces of the cell. The upstream face of each passage is adjacent and inclined at 90° to the downstream face of the other passage. A turret on the housing at each inlet and outlet is rotatable about its axis and has an angled coupling rotatable on the turret about an axis at right-angles to the axis of the turret. The inlet, upstream turrets each contain a filter and the outlet, downstream turrets each contain a centrifugal fan.

Abstract: An epidural catheter retainer has an integral base and hinged lid. The base is attached to the skin and has a side opening through which the catheter can be inserted sideways into the retainer. A channel extends laterally across the base and has protrusions to grip the catheter. When the lid is closed, it covers the side opening and is held down by a catch. The underside of the lid has teeth or the like to grip the upper side of the catheter so that the retainer isolates that part of the catheter in the body from force exerted on its other end.

Abstract: The current and voltage in an electrical system are monitored to detect an occurrence of an arc. The location of the arc is determined by propagating a pulse signal on the system in response to detection of the arc and timing the interval between reception of a portion of the signal reflected back from the location of the arc.

Abstract: A backshell 2 of an electrical connector has an outer nut 20 screwed onto the rear of the connector front assembly 1, which is formed with triangular locking teeth 13. An internal assembly 50 within the nut 20 prevents rotation of the backshell 2 on the connector when locked in position. The internal assembly 50 includes a rear cylinder 70 and a forward annular member 80 located between the cylinder and the front assembly 1. The cylinder 70 is of metal-plated plastics, which makes electrical connection at its rear end with screens 5 of cables 3 within the connector. The annular member 80 is of a metal and at its forward end has triangular teeth 85 that engage the teeth 13 at the rear of the front assembly 1. The rear of the annular member 80 and the forward end of the cylinder 70 both have rounded teeth 82 and 74 that engage with one another so as to avoid sharp edges on the cylinder that could lead to damage to its plating 170 caused by electrical transients.