Abstract: A low magnetic signature motor system (1) comprises a plurality of electric motors (2), a first shield (9) and a second shield (13). The electric motors are arranged with their associated magnetic moments (6, 7) forming a closed loop such that their net external magnetic field (5) is minimized The first shield comprises a material with a high electrical conductivity and substantially surrounds the electric motors such that the a.c. component of the magnetic field is reduced; and the second shield comprises a material with a high magnetic permeability and substantially surrounds the first shield such that the d.c. magnetic field is reduced.

Abstract: A fibre-optic surveillance system (10) includes a fibre-optic sensor (15) comprising a serial array (15) of fibre-optic point-sensors (16), successive point-sensors being linked by a distributed fibre-optic sensor (18). The system allows the location of intruder events along the sensor to be determined, and provides a reduction in the incidence of false-alarms compared to prior art systems.

Abstract: A focal plane detector adapted to be calibrated using an image of part of the human body. Further, a method of calibrating a focal plane detector having a plurality of detector elements, comprising the steps of presenting a first and a second image to the focal plane detector array, measuring the output from each detector during each first and second image, analysing the outputs and compensating for errors in the output of each detector element such that the outputs from the detector elements are substantially equal when illuminated with electromagnetic radiation of a given intensity. The first and second images have substantially no discernible features therein, and one of the first and second images comprises an image of part of the human body. The apparatus and method are particularly applicable to focal plane detectors sensitive to infrared radiation.

Abstract: A Mach-Zehnder type electro-optic modulator based, for example, on GaAs/GaAlAs of InP/InGaAsP comprises coplanar stripline (CPS) electrodes, and optical waveguides, disposed on a conducting substrate or a conducting epitaxial layer, wherein the regions underlying the CPS electrodes are selectively rendered insulating by ion implantation to electrically isolate the CPS electrodes.

Abstract: A micro-electromechanical system (MEMS) comprises a substrate incorporating an oscillatory ring, forcing electrodes for driving the ring into resonance, and sensing electrodes providing an electrical output signal dependent on oscillation of the ring as a result of such forcing and any externally applied force. A positive feedback circuit is provided for feeding back a signal dependent on the output signal of the sensing electrodes to the forcing electrodes in order to sustain oscillation of the ring. The use of positive feedback to drive the forcing electrodes in order to sustain oscillation of the ring is highly advantageous in such an application since it produces a system which exhibits very low phase noise of a magnitude considerably less than the phase noise experienced in use of a phase-lock loop circuit to sustain oscillation.

Abstract: The present invention relates to data mapping and involves the mapping of at least one feature from one data set to a corresponding feature in a second data set. Individual points of the features are initially mapped and an transformation for mapping the entire feature is derived from the individual mappings. The feature mapping may be used to enhance vehicle navigation, in feature tracking algorithms, and in image processing systems.

Abstract: Conventional analog loudspeakers have a limited dynamic range as compared to the available dynamic range of digital recordings. Digital recordings use up to 24 bits and this implies a dynamic range of 141 dB. Digital loudspeakers, involving 2N single bit devices (with N=24, this number is 1.7×107) have been proposed. The present improvement is the provision of at least one loudspeaker, a plurality of analog drivers and the audio input supplied to a control processor which in turn drives one or more of the plurality of independent analog drivers. The number of drivers in operation at any one time is determined by the amplitude of the input audio signal to the control processor.

Abstract: An apparatus for detecting ferromagnetic objects in the vicinity of a magnetic resonance imaging scanner. The apparatus comprises primary sensor means adapted to measure a magnetic field, arranged in communication with signal processing means configured to identify temporal variations in the measured magnetic field due to the movement of a ferromagnetic object within an ambient magnetic field and to provide an output indicative of the presence of a ferromagnetic object in the vicinity of the primary sensor means. The apparatus further comprises secondary, non-magnetic, sensor means adapted to detect the movement of objects in the vicinity of the primary sensor means in order to reduce false alarms. The output from the signal processing means may be used to operate an audible alarm, a visual alarm, an automatic door lock or a physical barrier.

Abstract: A method and apparatus for the spatial distribution of a filler component within the matrix of a composite material. An electric field is applied to a mixture consisting of two or more components that have different dielectric permittivities, at least one of which is initially in the form of a liquid polymer or pre-polymer. An alternating electric field is established between a pair of electrical conductors or electrodes that are moved relative to each other, so as to alter the spatial intensity of the electric field in a controlled manner. Polarized particles or elements of the filler component that are coupled to a moving electrode by a dielectrophoretic force can consequently be dragged into a predetermined spatial configuration. As the size of the inter-electrode gap is changed, the applied voltage can be adjusted in order to maintain electrically induced polarization of the filler component.

Abstract: A copolymer containing repeat units formed from the monomers (I) and (II), wherein each R1, if present, is independently hydrogen or hydrocarbyl; r is 0, 1 or 2; s is either 2 or 3; R2–R4 are each independently hydrogen or hydrocarbyl; R5 and R6 are each independently hydrogen, halo or hydrocarbyl; Pd? is the anion formed by loss of a proton from a proton donating group Pd—H; Z is either a bond or hydrocarbyl; R7 and R8 are each independently hydrogen, halo or hydrocarbyl; and either (a) A is an electron accepting group and W is either hydrogen or hydrocarbyl, (b) W is an electron accepting group and A is either a bond or hydrocarbyl or (c) both A and W are electron accepting groups. The invention also provides a method for preparing the copolymer by polymerising a mixture of (I) and (II) or their non-ionised precursors, preferably by exposure to ultraviolet radiation.

Abstract: A process analysis system for analyzing the efficiency of industrial processes includes a first radio system (104) associated with an input part of a processing system, and a second radio system (105) associated with an output part of a processing system, and a Radio Frequency Identification (RFID) tag associated with an item (103) to be processed, wherein the first and second radio systems are able to communicate with the RFID tag as it and its associated item pass through the processing system, and data associated therewith is stored on a data logging system. The system may be employed to check the time taken to process the item, or to check other parameters of the process, such as sorting accuracy for a sorting process. The system is particularly suited to use in waste product sorting and filtration systems, where RFID tags can be placed on a sample basis on items to be sorted, but may be applied to other suitable processes.

Abstract: A mineplough which is designed to be resilient to exploding mines comprises one or more blades set at an angle to the general direction of movement of the plough so as to deflect lifted earth to one or both sides of the plough and having tines arranged so as to lift earth ahead of the blade in the direction of travel thereof, depth control means for controlling the depth of cut of the tines and at least two linkages to connect the blade to a suitable carrier vehicle for the mineplough. The blade is comprised of a number of intersecting strong metal plates whose planes lie substantially parallel to the direction of travel of the mineplough and which define relatively narrow open channels therebetween so as to allow venting of any explosion caused by a mine exploding in contact with the blade.

Abstract: The use of a compound of formula (I) wherein R1 is an alkyl or alkenyl group, either of which may be optionally interposed with one or more oxygen or sulphur atoms, R2 is an alkyl or alkenyl group, Y? and Y? are independently selected from oxygen or sulphur, n is an integer from 1 to 5, X is a direct bond or a C1-4alkylene or C2-4alkenylene chain, and A is group comprising one or two rings which are independently selected from aryl, heterocylic or cycloalkyl rings, and when there are two rings, they are bonded together directly or by way of a C1-4alkylene or C2-4alkenylene group, for increasing the u.v. stability of a liquid crystal mixture. The compounds of formula (I) are u.v. stable and are useful in liquid crystal devices which are exposed to high levels of u.v. light such as phosphor display cells. Certain compounds are novel and these form a further aspect of the invention.

Abstract: A panel form loudspeaker comprises a resonant multi-mode radiator (11) which in turn comprises a plurality of substantially concentric sub-panels (20, 21, 22, 23). A plurality of analogue drivers (10) drive the radiator (11), one or more of the drivers being operational at any time. A signal level measured at the input to the loudspeaker determines the operational state of each of the drivers (10). The concentric sub-panels may take various shapes and have different areas.

Abstract: A reflective type liquid crystal optically addressed spatial light modulator has a first transparent substrate (1b), a first transparent electrode (2b) formed on the first transparent substrate (1b) and a photosensitive layer (3) formed on the first transparent electrode, formed from materials including hydrogenated amorphous silicon carbide (a-Si:C:H). A read-out light-blocking layer (4) is formed on top of the photosensor layer (3) and is formed from amorphous hydrogenated carbon (a-C:H). The high reflectance dielectric multilayer mirror (5) is formed on top of the light-blocking layer (4) and can be made of alternating the a-Si:C:H layers with a higher refractive index and the a-C:H layers with lower reflective index. The modulator also has a second transparent substrate (1a), a second transparent electrode (2a) formed on the second transparent substrate (1a), and a liquid crystal layer (8) disposed between the dielectric mirror (5) and the second transparent electrode (2a).

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 recogniser trained according to the method.

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: This invention relates to a proximity sensor. An illumination means (2) projects an array of spots (40) towards a scene. Detector (8) looks towards the scene through a mask (6). The mask (6) is arranged such that light from a target at a certain range, for instance far object (14) is not transmitted to the detector. Light reflected from a close object (16) however passes through the mask (6) and is incident on the detector (8). A rise in the intensity of incident light at the detector (8) is determined by threshold detector (10) and used to operate an alarm (12).

Abstract: A system and method for gathering and displaying information in data intensive environments. It is particularly concerned with data analysis in a critical care environment to provide a graphical display of derived information, comprising a series of bar charts representative of a corresponding series of functions. Each bar chart comprises a linear series of time-divided segments wherein each segment of each bar chart is assigned a colour corresponding to the status of that function. The status of each function is derived by scoring contributory data indicators in accordance with pre-set threshold values, and logically combining to produce a status score for each function. Interventions that affect particular functions may also be recorded and displayed against those functions so that their effect is readily discernible.

Abstract: Materials suitable for use in non-linear optical devices comprise morpholinium or thiomorpholinium salts of hydroxy-substituted aliphatic or aromatic carboxylic acids selected from tartaric acid and hydroxy-substituted benzoic and cinnamic acids, which salts have a non-centrosymmetric crystalline form. Preferred salts include morpholinium 3-hydroxybenzoate, morpholinium 4-hydroxybenzoate, morpholinium 3,5-dihydroxybenzoate, morpholinium 3-fluoro-4-hydroxybenzoate, dimorpholinium 2,3,5,6-tetrafluoro-4-hydroxybenzoate, morpholinium 4-(4-hydroxyphenyl)benzoate, morpholinium tartrate, morpholinium 4-hydroxycinnamate, thiomorpholinium 4-hydroxy-benzoate and thiomorpholinium 3,5-hydroxybenzoate.