Abstract: The application describes methods and apparatus for distributed fibre sensing, especially distributed acoustic/strain sensing. The method involves launching at least first and second pulse pairs into an optical fibre, the first and second pulse pairs having the same frequency configuration as one another and being generated such that the phase relationship of the pulses of the first pulse pair has a predetermined relative phase difference to the phase relationship of the pulses of the second pulse pair. In one embodiment there is a frequency difference between the pulses in a pulse pair which is related to the launch rate of the pulse pairs. In another embodiment the phase difference between the pulses in a pair is varied between successive launches. In this way an analytic version of the backscatter interference signal can be generated within the baseband of the sensor.

Abstract: A controlled differential, particularly for exercising steering control of skid steered vehicles, having a compound planetary gear set coupling two shafts. Respective ring gears turn with the shafts and mesh with a compound planet gear in a planet carrier, the ratios of the number of gear teeth between each ring gear and the respective gear of the compound planet being unequal so that when the planet carrier is stationary the two shafts are coupled through the differential to turn together in the same sense but with a speed difference, and controlled rotation of the planet carrier varies the speed difference between the shafts in accordance with the sense and speed of rotation of the planet carrier.

Abstract: The application describes methods and apparatus for distributed fibre sensing, especially distributed acoustic/strain sensing. The method involves launching interrogating radiation in to an optical fibre and sampling radiation backscattered from within said fibre at a rate so as to acquire a plurality of samples corresponding to each sensing portion of interest. The plurality of samples are divided into separate processing channels and processed to determine a phase value for that channel. A quality metric is then applied to the processed phase data and the data combined to provide an overall phase value for the sensing portion based on the quality metric. The quality metric may be a measure of the degree of similarity of the processed data from the channels. The interrogating radiation may comprise two relatively narrow pulses separated by a relatively wide gap and the sampling rate may be set such that a plurality of substantially independent diversity samples are acquired.

Abstract: The present invention relates to an improved sensor arrangement, a system and method for determining the rate of ice formation and how close conditions are to those at which ice will form on a surface, and to an improved sensor arrangement for use therein. The sensor arrangement comprises a means (11,12,14) for measuring the thermal lag, heating and cooling of a thermally conductive element, which is comprised of a first and second surface (15a, 15b), said first surface exposed to the environment, wherein the surface area of said first surface is smaller than the second surface. The step of ice detection may be performed by either a passive measuring system wherein the latent heat of ice formation is measured via the temperature differential across a Peltier element.

Abstract: An optical correlation apparatus is described which forms first and second parallel optical signals in response to a serial input data stream. The first parallel optical signal is arranged to have bright pulses represent binary 1 and the second parallel optical signal is arranged to have bright pulses represent binary 0. A channel select means, such as an optical switch or amplitude modulator, deselects or blocks channels in the first parallel optical signal which correspond to binary 1 in a reference data string and also deselects or blocks channels in the second parallel optical signal which correspond to binary 0 in the reference data string. The remaining optical signals are combined at one or more detectors. Where the input data matches the reference data string each bright pulse in the first and second parallel optical signals is deselected and the detector registers zero intensity. However when there is any mismatch at least one channel will pass a bright pulse to the detector.

Abstract: A load-limiting device is formed from a length of wire with a coil at each end defining eyes by which the device can be connected into a system adapted to be loaded in tension. The coils are of different diameter and the larger diameter coil is adapted to unwind by plastic deformation of the wire when the device is subject to a tensile load of a predetermined magnitude. The use of such devices in a system for deploying a vehicle arresting device across a roadway is also described.

Abstract: A respirator assembly e.g. for NBC protection is formed from two separate sub-assemblies. The first sub-assembly comprises a flexible hood (or other suitable headgear), a rigid mounting ring and a peripheral face seal. The second sub-assembly comprise a face plate with lens, oronasal mask and inlet and outlet valves, and is demountably attachable to the ring. The first sub-assembly can be worn on its own with the user breathing ambient air through the front end, the second sub-assembly being added if and when a hazard is encountered. The positioning of the face seal in the first sub-assembly means that a comfortable and reliable fit can be ensured when the sub-assembly is donned prior to a mission, but the user is relieved of the physiological burden of wearing the complete respirator unless and until protection is required.

Abstract: Ranging apparatus capable of projecting patterns of structured light tailored for use at particular ranges or depth regimes. Detected light points in a scene can be compared to pre-determined pattern templates to provide a simple and low cost gesture recognition system, for example as an interface to a smartphone or PDA. A structured light generator can be adapted to switch back and forth between said first and second structured patterns, either automatically according to a timing control, or adaptively in response to sensed information from the illuminated scene. Alternatively the structured light generator can be adapted to project the first and second patterns simultaneously. Separate light generators may be employed for the different patterns, or alternatively components can be shared.

Abstract: A method of target recognition performs a 3D comparison of target and reference data. Translation invariant signatures are derived from the two data sets, and an estimate of the orientation of the target with respect to the reference is obtained. Rotational alignment and comparison can then be achieved. The 3D data sets can be represented on an axi-symmetric surface such as a sphere and rotational convolution, over a discrete set of selected rotation angles can be performed. Optic flow can be used to derive the estimate of orientation or the target relative to the reference, in terms of a displacement field.

Abstract: An eye tracking apparatus and method of eye monitoring, comprising a target display adapted to project a moveable image of a target into a user's field of vision, an illumination source adapted to project a reference point onto a user's eye, a sensor adapted to monitor a user's eye, and a processor adapted to determine the position of a feature of a user's eye relative to the reference point, wherein the apparatus is arranged such that said determined position provides a direct indication of eye direction relative to the target direction.

Abstract: A method for automated selection of image regions (“tiles”) in an overall image includes computing a gray-level co-occurrence matrix and entropy of a green plane of the overall image, applying morphological closing to the matrix and thresholding the matrix and entropy image to provide binary masks. The matrix and entropy masks are combined with a vignette mask, the combination indicating areas of acceptable tissue from which tiles are selected randomly. For cancer grading; image data is transformed to Hue, Saturation and Value; for steroid/protein expression analysis it is transformed to cyan and a Sobel of cyan is computed. A feature measure is computed for each tile based on color and texture, and is carried out randomly but influenced by feature measure. Finally, from the further selection, tiles are chosen which combine high feature measure with low overlap.

Abstract: A system for automated checking of data content includes content checkers (208) to (214) arranged in parallel and connected between an input sub-system (204) and an output sub-system (216). The content checkers (208) to (214) check different data formats. Incoming data from an external computer system (202) is passed by the input sub-system (204) to the checkers (208) to (214), which report check results to both input and output sub-systems (204) and (216). From the four check results, the input sub-system (204) judges the data's acceptability for forwarding to a sensitive computer system (218). Unacceptable data is discarded; acceptable data passes to the output sub-system (216), which also judges the data's acceptability from the four check results.

Abstract: A data content checker arrangement for protecting communication between a sensitive computer system (102) and an external computer system (104). The arrangement includes a store (108) connected to input and output sub-systems (106) and (114) and to content checkers (110) and (112) arranged in parallel. The input and output sub-systems (106) and (114) are connected to the external computer system (104) and the sensitive computer system (102) respectively. Data received from the external computer system (104) is encrypted by the input sub-system (106) using an encryption key to which the content checkers (110) and (112) have access. The content checkers (110) and (112) can therefore decrypt, read and check the data. If the data passes a content checker's checks, the checker digitally signs and stores it, decrypted, in the store (108); if the checks are not passed, the checker discards the data.

Abstract: This invention relates to a novel insensitive munition comprising one warhead and also munitions comprising one or more warheads. In particular, the invention lies in the field of insensitive munition 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 at least two portions of high explosive separated by a non-detonative material, wherein each portion has a cross section below its critical detonation cross section, and wherein the at least two portions are arranged such that the total cross section of the at least two portions exceeds the critical detonation cross section of said high explosive, such that in use only simultaneous detonation of the at least two high explosives causes detonation to occur.

Abstract: A multistage flextensional transducer includes at least one inner elongate driver member within and mechanically coupled to an inner shell that is nested within an outer shell; the inner shell comprising a pair of contact portions abutting the driver member and a pair of transmission portions on opposite sides of the inner shell between the contact portions; the outer shell being arranged so that the transmission portions act as bridging driver members between the said inner and outer shells, flexure of the outer shell being driven, on actuation of the transducer, by movement of the bridging driver members. The transducer may act as a push or pull actuator or sensor, may magnify displacement and may employ smart materials as driver members. Also cylindrical modules containing thin flextensional actuators may provide axial displacement in a downhole environment and may move a device axially along a downhole pipe or close a valve opening or inch along the pipe.

Abstract: The present invention relates to the formation of electron spin EPR pairs and manipulation of such entangled electrons. The invention comprises a static quantum dot located part way along a quantum wire with means for adjusting the confining potential of the quantum dot. The quantum wire may for instance be formed by gate electrode (4, 6) with the quantum dot formed by a further gate electrode (8). The invention also comprises means for generating a electrostatic wave propagating along the wire, such as a surface acoustic wave transducer (10). In use a pair of electrons may be loaded into the static quantum dot and allowed to relax to a singlet ground state, in which the electrons are spin entangled. The propagating electrostatic wave acts as a series of quantum dots moving along the quantum wire.

Abstract: Apparatus comprising an optical fiber laser having at least two laser cores and means arranged to combine laser output from the at least two laser cores at a first end of the optical fiber laser to produce a combined laser output having one or more beat signals.

Abstract: A method of interrogating a phase based transducer by providing a pulsed input including two different wavelengths in which the different wavelength components can be used to derive a phase change experienced by a synthetic wavelength, and by arranging for the synthetic wavelength to be significantly greater that the component wavelengths, the phase so detected has a reduced sensitivity, and is less susceptible to overscaling effects.

Abstract: A wind turbine blade includes a multilayer composite structure including a first reflective layer, and a second layer including a plurality of resistive circuit analogue (CA) elements. The CA elements are tuned so as to interact with said first layer to provide absorption of electromagnetic (EM) energy over a desired frequency range. The parameters of the CA elements can be varied to provide for frequency tuning and to maintain absorption at a specific frequency range despite varying layer separation, while at the same time ensuring that the mechanical properties of the CA layer are compatible with integration into the turbine blade.

Abstract: A method of distributed acoustic sensing (DAS) whereby the derivative or rate of change of a signal backscatted from a fibre is measured. The change, or derivative of the phase measured in this way has a much smaller amplitude than the signal itself if the difference between the two times at which the signal is measured is much less than the period of the signal being measured, resulting in lower sensitivity. Frequency shifts can be applied to temporally displaced return signals to compare the rate of change, for example by employing an output interferometer arranged to modulate the signal in each arm by a different frequency shift.