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 ground pressure detonation device includes a housing, a foot coupled to the housing, and an oscillation subsystem associated with the housing configured to oscillate the housing such that the foot impacts the ground with sufficient oscillating force to ensure detonation of one or more pressure sensitive explosive devices in and/or on the ground.

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: A computer system for providing security in a computer network includes: a global sensor device configured to determine potential threats to the computer network; a global threat manager device configured to determine identification information associated with the potential threats; and a local security device configured to detect the existence of the potential threats based on the identification information and to take remedial action in response to the potential threats. The system also provides for responding to network attacks in a sufficiently granular method that is optimized according to the current state of the network by maintaining a virtual model of the network; detecting a network attack; generating a plurality of alternative candidate remedial responses to the network attack; and determining a potential network impact of each candidate remedial response using the virtual model of the network.

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, 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: 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.

Abstract: A terrain disruption device includes an air or gas flow generation device mounted on a remote operated vehicle having an extendible arm, wherein the air or gas flow generation device includes an elongate (optionally detachable) ducting arrangement to direct the air or gas flow and an optional nozzle. The air or gas flow generation device and/or the elongate ducting arrangement may be mounted on the extendible arm. Preferably, the air or gas flow generation device is powered by a fan, more preferably an electric ducted fan.

Abstract: An optical clock comprises a laser oscillator and modulating means arranged to cooperate with the laser oscillator to produce a series a series of phase-modulated optical pulses. The optical clock further comprises an optical fiber arranged to provide compression of the optical pulses, and may also comprise a step-recovery diode arranged to pulse-pick pulses output from the fiber to produce a series of optical clock pulses, depending on the mode of operation of the modulating means. Phase-modulation is carried out a frequency which provides sufficient linewidth broadening to inhibit stimulated Brillouin scattering within the optical fiber. An optical clock of the invention provides a robust and reliable alternative to clocks based on modelocked lasers, and may be assembled from inexpensive, commonly-available components. The repetition rate of a clock of the invention may easily be adjusted by electronic means. Unlike many modelocked lasers, a clock of the invention does not require precise optical alignment.

Abstract: This invention relates to a novel munition (1) comprising a controllable output warhead and also munitions comprising one or more of said warheads. There are further provided methods of preparing the warheads of the invention, methods of controllably detonating the warheads and a kit suitable for preparing such a warhead. The warhead comprises an inner and outer portion of high explosive (3, 4) co-axially located and separated by a non-detonative material (5), such that in use at least two output modes are possible, by either simultaneous detonation of both the inner and outer portion high explo-sives (3, 4) or selective detonation of the inner high explosive portion (3).

Abstract: An infrared detector comprising a plurality of bolometer detectors, bias circuitry for applying a bias to the bolometer detectors, and connectors for connecting the bolometer detectors together to form a network, wherein the bolometer detectors are arranged in an environment at substantially atmospheric pressure. A method for increasing the sensitivity of an infrared detector, having a plurality of bolometer detectors arranged in an environment at substantially atmospheric pressure so as to at least partly compensate for a reduction in the sensitivity of the infrared detector due to conduction of thermal energy from the bolometer detectors through the environment, the method comprising at least one of the steps of connecting the bolometer detectors together in at least one of series and parallel, and operating the bolometer detectors at a DC bias current.

Abstract: An optical fiber sensor assembly comprises a source of a plurality of different frequency substantially monochromatic signals (1, 2, 3, 4); a modulator connected to the output of the source to produce a train of output pulses of the monochromatic signals; a plurality of sensor sub-assemblies connected to the output of the modulator, each sub-assembly comprising an optical drop multiplexer (ODM) (13), a sensor array (14) comprising a plurality of sensor elements and an optical add multiplexer (OAM) (15); a wavelength demultiplexer (WDM), having an input coupled to the sub-assemblies output; a plurality of detectors, each detector having an input connected to receive a respective output of the WDM and providing at an output thereof a signal corresponding to a respective frequency of the modulated monochromatic signals; and an interrogation system, having a plurality of inputs connected such that each input receives the output signal from a respective detector.

Abstract: The invention relates to devices incorporating thin, lightweight electrochemical cells and their method of manufacture, whereby a thin flexible pouch-type cell (1) comprises at least one pair of overlying electrode layers separated from one another by an intermediate electrolyte layer (13), the cell exterior being defined by first and second laminated sheets (3, 9) sealed together, wherein each laminated sheet (3, 9) has an outermost layer (3a, 9a) forming a respective external face of the cell (1) and a coextensive, innermost, conductive layer (3b, 9b) that acts as a current collector layer (3b, 9b) and which supports an electrode layer (5, 11), although the conductive layer may also itself act as the active electrode layer.

Abstract: A generally planar, conformable evaporative structure, particularly for incorporation in a garment or an item of personal protective equipment as part of a system to cool the wearer's body, includes an envelope of substantially impermeable, flexible material containing: a layer of flexible wick material disposed adjacent to a major face of the envelope and adapted to hold a working fluid in liquid phase for evaporation by heat conducted through the envelope; a layer of flexible, breathable fabric in parallel with the layer of wick material; and an array of flexible ribs such as open helical coils within the layer of breathable fabric adapted to maintain pathways for the flow of working fluid in vapour phase towards a condensation zone.