Two phase medium identification using ultrasonic tomography technique
The use of tomographic techniques has been widely used in pipeline and oil industry. These techniques have potential applications for flow visualization and measurement in producing wells. One of the important processes is in multiphase characterization; that serve in monitoring, measuring or con...
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| Format: | Thesis |
| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/31304/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/31304/2/Full%20text.pdf |
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| Summary: | The use of tomographic techniques has been widely used in pipeline and oil
industry. These techniques have potential applications for flow visualization and
measurement in producing wells. One of the important processes is in multiphase
characterization; that serve in monitoring, measuring or controlling industrial processes.
Multiphase represents the condition of more than one medium phase. The identification for two phase medium is carried out in this research. Research on industrial tomography process revolved in obtaining estimated images in cross section of a pipe or vessel containing or carrying the substances in the process. Ultrasonic tomography technique is
one of the categories in process tomography. A simple tomography system can be built by
mounting a number of sensors around the circumference of a horizontal pipe. In this
research, sixteen pairs of 40 kHz ultrasonic sensor have been non-invasively mounted
around the pipe. The characteristic of the sensor is an important factor that needs to be
considered. Grease was used as the coupling material to mount these ultrasonic sensors.
The output data from the sensors were processed to obtain the information of the spatial
distributions of liquid and gas in an experimental column. Time of Flag (TOF) method has
been chosen to extract the data from the ultrasonic signals. Analysis on the transducers’
signals has been carried out to distinguish the observation time between the longitunal
(straight) propagation waves and the Lamb waves. The information obtained from the
observation time is useful for further development of the images. The Linear Back
Projection (LBP) algorithm has been applied to obtain concentration profiles or also called
tomograms. The results obtained through LBP were filtered using Gaussian Filter and
Enhancement Filter Technique. From the filtered images, further development was made
by extracting features information such as mean, standard deviation, skewness, kurtosis,
energy and entropy. Two approaches were applied for classification purposes using single
and combination of features. Comparison between K-Nearest Neighbor (k-NN) and Linear
Discriminant Analysis (LDA) classifiers have been made. From the observation, non-linear
classifier (k-NN) produced a better result over linear classifier (LDA). Furthermore, it has
been found that combination of features gives better performance over single feature
classification. |
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