| abstract |
An aerosol hazard classification and early warning network is composed of a large number of detector and analysis units, called "detector stations," which are deployed throughout a region to be warned of a potentially hazardous aerosol intrusion. Such aerosol threats may originate from fires, volcanic eruptions, or overt releases of biological and chemical agents dispersed in aerosol form. Among the former are the characteristic toxic aerosols released during refinery fires or explosions. The latter biological agents include bacterial spores, lyophilized bacterial cells, and virus preparations, whereas chemical agents might include various forms of nerve gasses and other anti-personnel gasses such as mustard, all commonly deployed in aerosol form. Each detector station contains an aerosol handling unit that samples and transfers ambient aerosol particles one-at-a-time through a light scattering chamber where each such particle is constrained to pass through a fine laser beam producing, thereby, an outgoing scattered light wave. The scattering chamber contains a plurality of scattered light detectors arranged to accept light scattered into different angular locations. The signals detected at each detector position are processed by a corresponding digital signal processing chip with the resulting set of digitized signals being transferred to an on-board central processing unit. The CPU analyzes the set of light scattering signals and identifies or otherwise characterizes each particle. The classification/identification data are then stored and, on preprogrammed command, telemetered to a remote "central station" by means of an on-board telemetry unit. The central station analyzes the sets of data received from all the detector stations and then instructs, as necessary, selected detector stations via telemetric means to change their sampling and telemetry rates. As soon as sufficient data are available, the central determines the presence, threat, extent, and progress of the aerosol cloud. These factors are then telemetrically transmitted by means of alarms and warnings sent to potentially threatened regions. |