Given the wide ranging concern about air pollution by particulates of sizes 2 to 10 µm, there is a need for a cost-effective, easily deployed, portable system of moderate accuracy (rather than high precision) for temporary use on sites or on board vehicles to monitor such particulate concentrations. This paper describes such a system, which is based upon a chromatic modulation technique. A brief explanation of the chromatic approach is given followed by a description of the particulate monitoring unit. The performance of this unit has been established via various calibration tests and the instrument has been deployed for real life use at a number of sites. Some preliminary results are presented from a city centre bus terminus, the depot of a major bus operator and a site close to an official monitoring station.

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One method for the identification of incipient transformer failures due to partial discharges involves measuring the concentration of dissolved gases in the transformer oil. The number of gases monitored is often considerable (⩾10), and there is a problem in tracking time varying patterns of the concentration of these gases to yield meaningful prognostic information. This contribution describes the use of chromatic processing techniques in the gas identification domain for yielding conveniently assimilable information in the form of chromatic maps for prognostic purposes. Such maps take the form of polar diagrams of various chromatic parameters such as hue (dominant species), saturation (breadth of gases per cent) and lightness (the overall concentration of gaseous species). Three categories of transformer working conditions (safe, alert and faulty) have been established based on such chromatic signatures. A simple probabilistic model, which can facilitate examination of the implication of future data gathered online, has been assembled.

The problem of extracting quantified information from physiological and physical indicators of the fatigue level of a vehicle driver is addressed. A chromatic approach has been used for processing the physiological and physical outputs from a driver fatigue monitoring system, the physical indicator being in the form of gyroscopic signals produced by the lateral movements of a vehicle. Some preliminary results are presented which show how the chromatic signatures of the physiological and physical indicators can be used to identify fatigue thresholds and provide a more optimized estimate of tiredness.

A technique is proposed for determining the location of an arc-discharge filament in a circuit breaker or a plasma torch utilizing only three photo-detectors, with the same spectral sensitivity, to observe the optical radiation emitted from the arc. The three detectors are placed at different azimuthal positions perpendicular to the central axis of the arc filament and are arranged symmetrically with respect to the central axis of the arc chamber and with their angular responses non-orthogonal. Outputs from the photo-detectors are analytically processed to yield two chromatic parameters, (the nominal radial mode) and (the dominant azimuthal mode), which define the arc location in the laboratory frame (, ). and are defined by algorithms used in chromatic processing. As an illustration, the technique has been applied to interpret some experimental results for determining the location of an arc filament lying within the nozzle of a gas-blast circuit breaker.