Abstract: A respirator has one or more electrodes of e.g. conductive elastomer disposed on the surface of a face sealing member opposite to the surface which seals against the user's face. In use the integrity of the seal formed between the sealing member and the user's face is monitored by monitoring the electrical capacitance across that member between the electrode(s) and the user's face.

Abstract: A drive configuration for a skid steered vehicle comprises a pair of electric motors for propulsion of the vehicle, one each coupled to drive a respective track on a respective side of the vehicle, and one or more electric steer motors coupled through a differential gear mechanism to impose a speed difference between the tracks. An associated control system controls the current to each motor so that substantial contributions to the differential torque to turn the vehicle are made both by the steer motors and by the propulsion motors, in variable proportions preferably as a function of the vehicle speed.

Abstract: A method of detecting a target in a scene is described that comprises the step of taking one or more data sets, each data set comprising a plurality of normalized data elements, each normalized data element corresponding to the return from a part of the scene normalized to a reference return for the same part of the scene. The method then involves thresholding (16) at least one of the normalized data elements of each of said one or more data sets. The thresholding step (16) comprises comparing each of the normalized data elements to at least first and second thresholds, wherein the first threshold is greater than the second threshold. The use of one or more confirmation scans (18) in combination with the thresholding step is also described. A radar system is also described that uses the method to detect foreign object debris (FOD) on a surface such as an airport runway.

Abstract: A semiconductor device comprising a plurality of regions of semiconductor material forming a junction at an interface there-between, the junction including a depletion region having a width which varies spatially in at least one direction along the depletion region. Without limitation, the spatial variation in depletion region width is provided by ionised dopants having a concentration which varies spatially along said at least one direction. Alternatively, or in addition, the spatial variation in depletion region width is achieved by varying the thickness of the region(s) of semiconductor spatially along said at least one direction, for example by creating a plurality of cells within said region(s) devoid of said semiconductor material. A method of fabricating a semiconductor device comprising the step of varying the width of the depletion region spatially there-within in at least one direction along the depletion region.

Abstract: A method for providing correction values for phase based measurements. Where averaging techniques are employed for exploiting redundancy in multiple measurements, by constraining the phase ambiguity in a correction value to be an integer multiple of the carrier wavelength, carrier phase based measurements can be used.

Abstract: Range-finding apparatus comprises a source of pulsed radiation of variable repetition rate and a beam-splitter for dividing the pulsed radiation into two portions which are directed respectively to a local retro-reflector and to a retro-reflector co-located with a remote target the range of which is to be determined. The source, beam-splitter and retro-reflectors are arranged in the form of Michelson interferometer together with a detector. The repetition rate of the source is tuned to frequencies f such that round-trip distance to the remote target is mc/f where m is an integer, this condition being detected by observing a heterodyne signal at the detector. Two such frequencies enable range to be determined. The precision with which range is determined may be increased by carrying out interferometry using the two portions. The accuracy of the method does not depend on absolute range (as with triangulation) and is not limited by the speed of timing electronics, as is the case for time-of-flight techniques.

Abstract: This invention relates to the field of an electromagnetic (EM) field shielding paint compositions, in particular, those capable of providing substantially non metallic finish. The paint composition finds particular use in attenuating EM signals that may be used to carry data between communication devices, especially mobile phone and wi-fi devices. EM field shielding paints are typically available in jet-black or bright metallic finishes and usually possess limited scratch & abrasion resistance. The paint composition provides a one-pot solution to furnish a composition which has the visual appearance of a domestic type paint i.e. one with a non-metallic finish, with the ability to shield electromagnetic radiation. The composition comprises a supported metallic flake and a pigment, which have been provided in a narrowly defined range to furnish a desirable non-metallic appearance and possess electromagnetic shielding properties.

Abstract: An oil and gas well shaped charge perforator capable of providing an exothermic reaction after detonation is provided, comprising a housing (2), a high explosive (3), and a reactive liner (6) where the high explosive is positioned between the reactive liner and the housing. The reactive liner (6) is produced from a reactive composition which is capable of sustaining an exothermic reaction during the formation of the cutting jet. The composition is a pressed i.e. compacted particulate composition comprising at least two metals, wherein one of the metals is present as spherical particulate, and the other metal is present as a non-spherical particulate. There may also be at least one further metal, which is not capable of an exothermic reaction with the reactive composition, present in an amount greater than 10% w/w of the liner. To aid consolidation a binder may also be added.

Abstract: A method for the alignment of pairs of complex images of a region, such as may be produced by separate passes of a synthetic aperture radar, is disclosed. The method selects a subset of each image in the form of a plurality of tiles, and calculates a correlation value between corresponding pairs of tiles. Shifts in x and y for each pair where the correlation value exceeds a threshold are then used to calculate values for overall shift, stretch and shear to be applied to one of the images to align it with the other. An iterative least squares approach may be used. As both phase and amplitude information is used in the correlation the technique is suitable for aligning images having little intensity variation. The invention may be used to align images prior to coherent change detection analysis of the images.

Abstract: A retro-reflective identification tag capable of modulating an optical signal whereby to support bi-directional communication with an associated remote optical interrogation device. The tag comprises a MOEMS modulating layer over a retro-reflective substrate, giving the tag a wide angle of effective operation. The tag modulator may optionally be switched on only responsive to detection of a precursor beam from the interrogation system in order to save power. The interrogation device may make use of multiple optical wavelengths for communicating with the tag.

Abstract: The invention relates to processes for the preparation of electrode compositions, especially those intended for use in supercapacitors. A process is provided for preparing lithium sulphite comprising the steps of:—a) introducing H2SO3 (aq) into a reaction vessel; b) reacting the H2SO3 (aq) with an aqueous suspension of Li2CO3 in the vessel to form an aqueous solution of Li2—CO3; and c) evaporating the solution to recover Li2CO3(s), wherein at least steps a) and b) are conducted under an inert atmosphere. Preferably, in step b) H2SO3 (aq) and Li2CO3 (aq) are reacted with each other in substantially equimolar amounts. There is also provided a process for forming an electrode material comprising a complexing step of causing lithium sulphite to form SO3 complexes at active N sites of a nitrogen-carbon structure, in the presence of a selected amount of a sink that absorbs the liberated lithium, so as to form the N:SO3 complexed electrode material.

Abstract: A one-way valve for use in the inhalation and/or exhalation flowpath of respiratory protection equipment comprises a housing 1 defining a conduit and a circumferential array of three flexible flaps 2 each extending inwards from the conduit wall and in the direction away from the inlet end I of the valve. Under a pressure differential in the opening direction of the valve each flap is adapted to flex outwards towards the conduit wall and under a reverse pressure differential the free edge 5,5 of each flap is adapted to press in sealing contact with respective portions of the free edges of the neighbouring flaps.

Abstract: An unmanned aerial vehicle (UAV) in the form of a “tail sitter” flying wing adapted for vertical take off and landing and transitions between flight as a helicopter and wing-borne flight. The vehicle is electrically powered from onboard batteries and equipped with rotors on miniature helicopter rotor heads at the tips of the wing for both lift, during take off and landing, and forward thrust. In planform the wing comprises, to each side of its longitudinal axis, an inner section with swept back leading and trailing edges, and an outer section with a leading edge more perpendicular to the longitudinal axis, being only mildly swept back or substantially unswept, and a swept forward trailing edge.

Abstract: A bistatic laser radar (lidar) device is described that comprises a transmit channel (60) for forming a focused transmit beam, and a receive channel (62) for forming a focused receive beam. The device is arranged such that the focus of the transmit beam and the focus of the receive beam fall on a common axis when focused to a distance within the operable distance range of the device. The device may be used for vibrometry, wind speed measurements and the like. Implementation of such a device using optical fiber based components is described.

Abstract: An improved photocell offering efficient power generation from broadband incident radiation, the photocell includes a first diode formed in single crystal silicon and one or more further diodes each formed in a single crystal Group II-VI semiconductor. In a preferred embodiment, a tandem photocell is provided that incorporates a first diode formed in single crystal silicon, a second diode formed in a Group II-VI semiconductor, an optional buffer layer and a highly doped layer of silicon acting as an optional tunnel junction between the two diodes. The device can additionally include a layer of silicon deposited at the rear of the structure to maximise current collection of longer wavelength light, and top and bottom (front and back) electrical contacts. In use, light impinges on the top (front) surface of the photocell and is absorbed (in turn) by diodes.

Abstract: A method of measuring the reflectivity of a region of an article to electromagnetic radiation, in particular for the characterisation of the radio-frequency (RF) properties of wind turbine blades. The article (10) is arranged in the near-field of a transceiver antenna (4), which performs both illumination and measurement of reflected radiation from the region of the article the article undergoing measurement. The method is beneficial in that it can be used with an antenna in close proximity (or in contact) to the article to be measured, for example for use in on site measurement of specific regions of a turbine blade.

Abstract: Methods, apparatus, and programs for a computer for network security content checking: in particular ones which simplify the critical element of a content checker so it can be trusted and implemented in logic.

Abstract: The invention enables thin film particles of a controlled shape and size to be generated directly upon release of a thin film coating from a textured Substrate upon which they are grown directly. The substrate comprises an array of discrete, steep sided plateaus of a selected size and shape, from which discrete particles of a corresponding shape and size are releasable usually by means of an intermediate release layer coating on the plateaus. The process is readily scalable for high volume production and permits monomodal or multimodal particle size distributions. Such particles may be used as specialised pigments in the security, anti-counterfeiting, defence and cosmetics industries.

Abstract: Methods and apparatus for network security content-checking, in particular simplifying the critical element of a content-checker so that it can be trusted and implemented in hardware logic. A method comprises determining whether a digitally encoded document contains any embedded documents; content-checking, by means of at least one hard-ware-implemented content-checker, at least one of the embedded documents separately from those parts of the digitally encoded document within which it was embedded; and releasing a version of the digitally encoded document responsive to the content-checking.

Abstract: Isopotential heaters used in the preconcentration stage of sample detection systems are described. The heaters have at least two electrically conducting paths of which the resistances of the electrically conducting baths are substantially equal such that in use uniform heat distribution is achieved.