| Summary: | Increasing applications of Pe's in industry has led to the concept of the Virtual Instrument (VI), allowing greater flexibility and ease of modification for different situations, making Virtual Instrumentation increasingly favourable over traditional standalone instruments. This thesis provides insight into the uses of VI techniques for tomographic imaging, using proprietary hardware and software, applied to a pneumatic polypropylene transportation system. The VI based tomographic imaging system is used as part of a flow control mechanism and is used for mass-flow measurement and analysis. The thesis presents an introduction to Electrical Capacitance Tomography and its applications for process monitoring in particular, for use with the MMU flow rig, which emulates the pneumatic conveyance of solids for ~ typical industrial system. An argument for the selection of Virtual Instrumentati~n for tomographic imaging is . presented and the benefits and limitations discussed. An overview of tomographic imaging is presented, from basic electrical field concepts and their associated' data normalisations techniques for the generation of permittivity images to various reconstruction methods. Details -of proprietary and application specific hardware is given, two distinct ECT imaging systems using the AC-bridge capacitance detection technique have been developed. An 8-electrode serial capacitance data acquisition system and a higher performance 8/12-electrode parallel data acquisition system. Both ECT imaging systems utilise a National Instruments based PXI instrumentation platform and LabVIE\y graphical programming environment. A discussion on the implementation of the software developed for both ECT systems, highlighting some of the software optimisation strategies employed and an evaluation of the ECT systems is presented. The performance of each tomographic system in terms of image accuracy and speed and the differences between an 8electrode and a higher resolution 12-electrode imaging system is analysed. The applications of the VI based tomographic imaging systems are discussed, both the serial and parallel 8-electrode being successfully applied to flow control using Artificial Neural Networks. The dual-plane imaging capability of the parallel system has allowed accurate measurement of terminal velocities for vertical pellet flow and is used for mass-flow measurement using cross-correlation. A Virtual Instrument, incorporating a Tomographic system capable of imaging pneumatically conveyed pellets in the MMU flow rig, has been designed and built using LabVIEW software running on an embedded Pentium-4 PXI controller. This has resulted in a system which is independent of the standard PC platform and is a robust system, capable of use in an industrial environment. Advantages of using the PXI system include having an imaging system that uses proprietary interchangeable hardware, that can be easily modified. In addition it lends itself to a platform that can be used for developing powerful tools using LabVIEW and Matlab. The VI Measurement System VIMS has shown distinct advantages for applications where fast frame rates are not critical but design flexibility and low development costs are required.
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