Abstract: An optical wavelength division multiplexer/demultiplexer device is described that comprises a substrate having a plurality of wavelength selecting filters. The filters are arranged to provide conversion between a combined beam comprising a plurality of wavelength channels and a plurality of separate beams each comprising a subset of said plurality of wavelength channels. Hollow core waveguides are formed in said substrate to guide light between the wavelength selecting filters. An add/drop multiplexer is also described.

Abstract: An electric drive transmission for a skid steered vehicle has a central casing housing a pair of propulsion motors comprising respective stators and rotors, each rotor being coupled to drive a respective through shaft via a respective epicyclic gear change mechanism. The through shafts are coupled at their inboard ends to a controlled differential with an input from a steer motor, and are coupled at their outboard ends to respective epicyclic gear reduction mechanisms. The through shafts are supported in the casing by respective bearings and the propulsion motor rotors are supported on the through shafts by respective bearings. By supporting the rotors on the through shafts rather than in separate bearings to the casing the diameter and speed rating of the requisite rotor bearings can be reduced.

Abstract: A high pressure pump for use in the injection of liquid chemicals into subsea oil or gas wells, and intended to be positioned in the subsea environment adjacent to the wellhead, comprises a piezoelectric actuator (19) for reciprocating a plunger (22) which acts to compress and expand the effective volume of a pumping chamber (29) having a valved inlet (15) connected to a source of the liquid and a valved outlet (16) to lead the liquid to the well. The device has a minimum of moving parts and in particular avoids the need for any rotating parts and attendant high performance bearings and seals.

Abstract: A man portable hydrogen source, the source comprising one or more hydrogen generating elements, an ignition control system and a pressure vessel. Each hydrogen generating element comprises a pellet holder provided with one or more recesses and a thermal insulation layer to reduce heat transfer to adjacent hydrogen generating elements; wherein at least one recess contains a pellet of a chemical mixture which on thermal decomposition evolves hydrogen gas; wherein the ignition control system comprises one or more igniters, associated with an individual pellet, and activation means to activate the igniters; and wherein the evolved hydrogen and hydrogen generating elements are contained within the pressure vessel.

Abstract: This invention relates to a pattern recognition correlator implemented entirely in the electronic domain. The correlator has a serial to parallel conversion means to convert input serial binary data into at least one input parallel binary electrical signal and a comparator to compare the or each input parallel data signal with a reference parallel binary data signal. The serial to parallel conversion means may comprises a demultiplexer to effectively slow the data update rate and a series of latch circuits to provide the parallel data signal. The comparator may be arranged to perform bit addition and may be arranged such that a zero total sum is an indication of correlation. The bit addition may be performed b an array of logic gates.

Abstract: A single sided RF tag suitable for use for electronic article surveillance comprises a tuned circuit formed on one side of a substrate. Provided by a deposited first conducting layer which comprises an inductive coil, which behaves as an antenna and is electrically connected to a first capacitor plate and a connection means to connect to a second conducting layer. A low dissipation factor dielectric layer is deposited onto said first conducting layer. A second conducting layer comprising at least one capacitor and a connection means to electrically connect to the first conducting layer is deposited on the dielectric layer. The second capacitor plate is substantially co-located above the first capacitor plate, to form the capacitor. The capacitor and coil together form a resonant circuit.

Abstract: An antenna system having a transmissive surface and an antenna arranged to transmit or receive radiation through the transmissive surface via a radiation lobe of the antenna. The system further includes a displacing arrangement to displace the radiation lobe of the antenna relative to the transmissive surface as necessary so as to reduce a change in one or more characteristics of the radiation on passing through the transmissive surface. A corresponding method is additionally described.

Abstract: A method for the automated analysis of digital images, particularly for the purpose of assessing nuclear pleomorphism from images of histological slides for prognostication of breast cancer. The method includes the steps of identifying the locations of objects within the image which have intensity and size characteristics consistent with epithelial cell nuclei and deriving boundaries for those objects. Statistics concerning at least the shapes of the derived boundaries are calculated and clutter is rejected on the basis of those statistics and/or they are used to assign probabilities that the respective objects are epithelial cell nuclei, and a measure of the variability of at least the areas enclosed by such boundaries is then calculated.

Abstract: The biasing spring of a valve is excited and the response detected to determine valve characteristics. Excitation is typically longitudinal oscillation applied by a vibrator connected in series with the spring. By performing a frequency sweep, resonance can be detected, and excitation can usefully be applied at the resonant frequency to produce valve lift. Testing can be performed in-situ, and maintenance of a plurality of valves is possible by collecting characteristic data for each valve and comparing against stored values.

Abstract: Apparatus for scanning a moving object includes a visible waveband sensor 12 oriented to collect a series of images of the object as it passes through a field of view 16. An image processor 14 uses the series of images to form a composite image. The image processor 14 stores image pixel data for a current image and a predecessor image in the series. It uses information in the current image and its predecessor to analyse images and derive likelihood measures indicating probabilities that current image pixels correspond to parts of the object. The image processor 14 estimates motion between the current image and its predecessor from likelihood weighted pixels. It generates the composite image from frames positioned according to respective estimates of object image motion. Image motion may alternatively be detected by a speed sensor such as a Doppler radar 200 sensing object motion directly and providing image timing signals.

Abstract: The need to have a large single crystal of photorefractive material for devices such as optical limiters, optical memory, and beam couplers, is avoided by providing a photorefractive body (42) comprising small photorefractive particles (44) coupled by a couplant (43), for example glass, which is refractive index-matched to the particles. Such a body may comprise a fiber (42), or a bulk body (80). For many uses it will be necessary to align the photorefractive particles in the body and this can be achieved using fluid flows or electrostatically. Methods of making the particles, and of making photorefractive bodies are disclosed. Devices incorporating particle-couplant matrix bodies are disclosed.

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 modulators 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 signal processing system is disclosed which is implemented using Gaussian Mixture Model (GMM) based Hidden Markov Model (HMM), or a GMM alone, parameters of which are constrained during its optimization procedure. Also disclosed is a constraint system applied to input vectors representing the input signal to the system. The invention is particularly, but not exclusively, related to speech recognition systems. The invention reduces the tendency, common in prior art systems, to get caught in local minima associated with highly anisotropic Gaussian components—which reduces the recognizer performance—by employing the constraint system as above whereby the anisotropy of such components are minimized. The invention also covers a method of processing a signal, and a speech recognizer trained according to the method.

Abstract: An optical correlation apparatus is taught which provides a parallel optical signal having a phase modulation representing input data to which a parallel phase modulation based on reference data is applied. In the event of correlation the resulting wavefront is planar and can be interferometrically coupled to give a high intensity signal. The invention involves use of parallel amplitude modulation means for selectively blocking the optical signal in one or more of the channels of the parallel optical signal which allows different sized reference data strings to be searched more easily and also aids in calibration.

Abstract: An antenna system comprising an array of antenna elements, the array comprising a plurality of groups of antenna elements wherein each group comprises one or more antenna elements arranged in series, and wherein the system further comprises first phase-control means for performing the function of introducing respective phase-shifts to transmitted or received signals passed to or received from each of said groups to provide beamforming and second phase-control means for performing said function with respect to a sub-set of said groups. An antenna system of the invention allows two radar beam patterns having different spatial characteristics to be generated using a single antenna system. The invention also provides a radar system incorporating an antenna system of the invention.

Abstract: Inflatable members for incorporation into a fascine are linked together at their ends by chains or other such flexible tension members, the tension in which is such as to cause at least local compression and flattening of the inflatable members where they are in contact with adjacent members. The forces so generated between adjacent members can prevent their tendency to rotate under the action of traffic crossing the fascine.

Abstract: Traffic sensing and monitoring apparatus (100) comprises a length of optical fiber (112), means (102, 103, 104, 106, 107, 109, 119) arranged to introduce a series of pulse pairs into an input end of the length, each of the pulse pairs comprising first and second pulses of radiation having a frequency difference ? and the second pulse being delayed with respect to the first by a delay ?, and the apparatus further comprising a photodetector arranged to detect radiation which is Rayleigh-backscattered within the length of fiber towards the input end to generate an output signal in response thereto. Apparatus of the invention allows sensing and monitoring of traffic at any position along a long length of road (e.g. 5 km) with lower installation and maintenance costs per unit length compared to prior art systems providing the same spatial resolution.

Abstract: An imaging spectrometer is disclosed that comprises imaging means for dividing a received image into two or more spatially separated images and means for detecting each spectral image, and is characterized in that the imaging means comprises at least one polarizing beam splitter. The polarizing beam splitter may be a Wollaston prism. In one embodiment of the invention, the imaging means comprises image replication means to produce two or more spatially separated images, and one or more filter elements such as dichroic filters which act to alter the spectral characteristics of one or more of the spatially separated images. In a further embodiment of the invention the imaging means comprises one or more spectral replication means arranged in optical series, each spectral replication means comprising an optical retardation element and a polarizing beam splitter.

Abstract: A method of detecting a target in a scene comprises the steps of generating a comparison of the value of data elements in first and second data sets, the data elements corresponding to returns from the same part of the scene and setting a detection threshold value for the comparison so as to detect targets entering said that part of scene The method provides improved target detection in the presence of clutter.

Abstract: A method of scoring Oestrogen and Progesterone Receptors expression (ER and PR) from histological images determines the percentage of brown image blob area in total blob area and derives percentage thresholds to quantify scoring. Brown blob area proportion is then compared with the thresholds to provide a first contribution to scoring of ER or PR. The number of relatively dark pixels is then counted, pixel number thresholds are determined to quantify scoring, and the number of relatively dark pixels is compared with the thresholds to provide a second contribution scoring of ER or PR. The two contributions are then added to provide an overall scoring in the range 0 to 8 which may be taken as a final score or it may be scaled to a conventional range 0 to 3.