Abstract: A handheld probe comprises means for sensing a physical property such as current, voltage, temperature and pressure by locating the probe in contact with an article or in close proximity to an article, a battery for alimenting the probe, and means for wirelessly transmitting sensed data from the probe to a display unit spaced from the probe.

Abstract: A method of comparing two nominally identical entities each of which can be represented by an assembly of arcs, comprising the operations of producing images of the entities, analysing each of the images into an assembly of arcs, producing respective data sets representative of the arcs in the assemblies, using the data sets to map one assembly of arcs onto the other, determining differences in the mapping related to differences between the images, comparing the determined differences in the mapping between the images with statistically determined differences in the mapping between a plurality of authentic images to establish a criterion of an acceptable level of probability of identity between the said two entities and providing an indication of the acceptance or rejection of the proposition that the two entities are identical.

Abstract: An aerosol generator (10) includes a plate (18) defining an orifice (20) through which a jet of liquid is projected, which breaks up into droplets. The plate (18) is vibrated to control the droplet size, and the size distribution. The droplet size distribution is monitored, and this information is used to control the vibration to ensure the droplets are monodisperse and of the correct size. This can be achieved as follows: the droplets are diverted by a transverse air stream, and an optical image is obtained of the diverted jet (28) onto a linear array of photodetectors (34). The signals from the photodetectors represent the particle size distribution, and are supplied as input to a computer (36) whose output is used to control the vibration of the plate (18).

Abstract: An electrochemical cell (50) for deionizsation utilizes electrochemical ion-exchange to remove ions from a feed solution. Under the influence of an electric field, ions are adsorbed into, are scored within and pass through a permeable layer (54, 64) of particulate ion-absorbing material and binder, the sheet being several millimeters thick. Water from the feed solution also permeates through the layer (54, 64), so a concentrated solution of the ions emerges from the rear (58) of the layer. The cell does not require separate sources of feed and eluant solutions and can be operated substantially continuously. In a modified cell (70) the flow path for the feed solution passes through a highly porous ion exchanger structure (77), which may be located between two such microporous layers (54, 64). Absorption in such a cell may be effective in the absence of an electric field, elution requiring the periodic application of the electric field.

Abstract: A light source including a gaseous medium which is excited to a light-emitting state by means of a microwave electromagnetic field, wherein the electromagnetic field is generated by circularly polarised microwave radiation. A preferred form of the invention is a laser.

Abstract: An electrically conducting filter medium (20) is cleaned in situ by applying, at intervals, a brief voltage pulse between the medium (20) and a counter electrode (18) so the process liquid undergoes electrolysis. The cleaning process is significantly improved by occasionally applying a voltage of reverse polarity. For example a 5 second cleaning pulse making the filter medium (20) cathodic might be applied every quarter of an hour, and a reverse polarity pulse of similar duration applied every two hours. This process can significantly increase permeation rates.

Abstract: Effluent streams from photographic processes contain both silver and thiosulphate ions, and because of the formation of complex anions it is difficult to remove the silver. The silver may be removed using a cell (12) with a cathode (24) exposed to the effluent liquid, and an anode (25) separated from the liquid by a barrier (22) permeable at least to anions. Some silver sulphide is formed electrochemically at the cathode (24); at the anode (25) water is electrolysed and becomes acidic, so the complex anions migrating through the barrier (22) generate silver sulphide chemically. The resulting silver sulphide precipitate is separated from the liquid by a filter (14).

Abstract: A method of sterilising objects including the operations of activating a gaseous medium, ensuring that the activated medium is substantially free of charged species and exposing the object to be sterilised to the activated gaseous medium for a period sufficient to ensure that the object is sterilised.

Abstract: An apparatus for producing chemically active species by passing a precursor gaseous medium through a plasma at pressures of at least 50 millibars is described.

Abstract: An eddy current testing system consists of a multi-sensor probe, a computer and a special expansion card and software for data collection and analysis. The probe incorporates an excitation coil, and sensor coils; at least one sensor coil is a lateral current-normal coil and at least one is a current perturbation coil.

Abstract: The movement of particles carried along with a fluid is detected by isonifying a region of the fluid with pulses of ultrasound, and detecting pulses of ultrasound scattered by an individual particle from successive transmitted pulses. The difference in arrival times of successive detected pulses is simply related to the speed of the particle. Use of suitable gates (A, B) enables successive reflections from a particle to be tracked while reflections from other particles are rejected.

Abstract: Electrochemical insertion of lithium into titanium dioxide initially in its rutile form, the insertion being performed at an elevated temperature (for example 120.degree. C.), produces a material Li.sub.x TiO.sub.2 with x between 0.5 and 1.0. This material is suitable as an active cathode material in a secondary cell as it can be repeatedly recycled. The material has a crystal struture, different from that of the initial rutile titania, which is believed to be hexagonal.

Abstract: A secondary cell includes as its active cathode material a first insertion material, such as V.sub.6 O.sub.13, into which ions are inserted during discharge. To prevent irreversible lattice changes leading to a decline in capacity the discharge should be terminated before a threshold cell voltage is crossed. Such irreversible changes are suppressed by including in a surface coating of the cathode a minor proportion of a second insertion material, such as a titanium oxide, whose discharge commences before the threshold cell voltage is reached.

Abstract: A method of removing particulate and other materials from the exhaust gases from an internal combustion engine in which the exhaust gas is passed through a bed of charged ferro-electric materials. Three forms of apparatus for carrying out the method are described.

Abstract: A hard-wired circuit (25) is provided for controlling or for monitoring a plant or process (12). The circuit incorporates means (14) to sense the current state of the process, an input encoder (16) to generate multi-digit binary coded signals representing that sensed state, and an output encoder (18) to generate multi-digit binary output coded signals corresponding to the signals from the input encoder (16), which output signals can be used to control process or plant actuators. Both the input encoder (16) and the output encoder (18) may be PROMs. A complement modulator (20) activated by an oscillator (24) may be used to provide dynamic output signals; and by means of appropriate comparators (26, 38) and watchdogs (28, 40) the input and output coded signals may be verified.

Abstract: A microwave plasma generator including a chamber within which there is a pair of opposed field-enhancing electrodes one of which has an axial hole through which gas which has been activated into a plasma state in the region between the electrodes can be extracted from the chamber.

Abstract: A processing vessel (10) for a liquid includes an impeller (32) in an open-ended shroud (30) to cause circulation. The base of the vessel (10) communicates with a short duct (18) closed at its lower end, and the shroud (30) is shaped to ensure circulation into this dead-end duct (18). The duct is provided with ultrasonic modules (24) so that its contents are subjected to intense insonation. The insonation of the liquid can lead to improvements in the product of processes such as crystallization.

Abstract: A joint of a hydraulic manipulator connects two hollow arm members and includes two indirect linkage members arranged to provide increased scope for the joint. Hydraulic hoses or cables extend through the hollow arm members, so as to be protected, and along a route which intersects the centre axis of the joint so they are not stretched as the joint bends.

Abstract: A pressure transducer comprises a polycrystalline diamond diaphragm (39), produced by use of a chemical vapour deposition technique, on a support (33). The diaphragm (39) can deflect in response to variations in pressure. A single optical fibre interferometer (36, 32) is used for detecting and measuring the deflection of the diaphragm (39) (FIG. 3).

Abstract: A fluid flow control system in which a vortex valve is combined in series with a non-fluidic control valve. The non-fluidic control valve is upstream of the vortex valve and is so arranged that small changes in its state control the operation of the vortex valve, which provides the major control over the flow of the fluid. Erosion in the non-fluidic valve due to abrasion or cavitation in the non-fluidic valve is thereby reduced.