A charge coupled device based optical tomographic instrumentation system for particle sizing.

This research investigates the use of charge coupled device (abbreviated as CCD) linear image sensors in an optical tomographic instrumentation system used for sizing particles. Four CCD linear image sensors are configured around an octagonal shaped flow pipe for a four projections system. The measurement system is explained and uses four CCD linear image sensors consisting of 2048 pixels with a pixel size of 14 micron by 14 micron. Hence, a high-resolution system is produced.Three main mathematical models based on the effects due to particles, light sources and diffraction are discussed. The models simulate the actual process in order to understand the limitations of the designed system.Detailed design of the optical tomography system is described, starting from the fabrication of the 'raybox 'of the lighting system, the design of the driving circuit in the detection system, the timing and synchronisation in the triggering system based on the PIC microcontroller and the data acquisition system.Image reconstruction for a four-projection optical tomography system is also discussed, where a simple optical model is used to relate attenuation due to variations in optical density, [R], within the measurement section. Expressed in matrix form this represents the forward problem in tomography [S][R]=[M] In practice, measurements [M] are used to estimate the optical density distribution by solving the inverse problem [R]=[S]-1[M]. Direct inversion of the sensitivity matrix, [S], is not possible and two approximations are considered and compared - the transpose and the pseudo inverse sensitivity matrices.The designed instrumentation system is calibrated using known test pieces and tested for accuracy, repeatability and consistency among measurements from different projections. The accuracy of the particle size measurement using the system is within 1 pixel i.e. + 14 micron (the maximum absolute error of 8.5 micron), with the maximum percentage error of 1.46%. Moreover, the system has a good repeatability and consistency - within 1.25 pixel. The range of particle size that has been tested using the system is between 0.18 mm up to 11 mm diameter. A spherical shaped and an irregular shaped particle are tested on the designed system to complete analysis of the overall performance of the system.This thesis is concluded with achievements of objectives of the research, followed with suggestions for future work

Hardware development of reflection mode ultrasonic tomography system for monitoring flaws on pipeline

The pipeline inspection is a key requirement to maintain structural health and pipeline integrity for oil and gas transportation over countries. Pipe failure is a critical problem that needs to be endured within the operational work. The defects or flaws existence on pipeline surface is one of the most leading factors to pipe failures. A new approach of non-destructive technique is implemented to monitor flaws on pipeline by using reflection-mode ultrasonic tomography system. This paper details on the hardware development of ultrasonic tomography system based on reflection mode detection. The system consists of ultrasonic transceiver sensors mounted circularly and contactless to the pipe surface. The modeling work described the ultrasonic ring configuration, ultrasonic signal behavior, sensors arrangement and image grid estimation. The developed instrumentation system is used to detect external and internal flaws on pipe surface. The results show that the reflection-mode ultrasonic tomography is capable to differentiate flaws detected based on the calculated depth verified from the distance measured and through the reconstructed image

The use of reflection mode ultrasonic transceiver sensor in pipeline inspection guage to monitor pipeline internal corrosion

Aging gas transmission pipelines are prone to internal corrosion due to the presence of carbon dioxide and hydrogen sulphide in the natural gas constituents. Commonly, the in-line inspection tool known as Pipeline Inspection Gauge (PIG) is applied to perform the corrosion inspection of the pipeline. This paper describes an ultrasonic instrumentation system for PIG to monitor internal corrosion of pipeline. The system consists of ultrasonic transceiver sensor, ultrasonic driving circuitry and data acquisition system. The hardware is equipped with a sensor carrier which is propelled along the test pipeline. The time of flight (TOF) of the ultrasonic wave is measured and was used to evaluate the internal corrosion of pipeline. An initial experimental instrument was set up to perform the distance measurement test at a frequency of 390 kHz, to simulate the changes of pipe wall thickness due to corrosion effect. Surface anomalies were created at different positions to simulate the changes of pipe wall thickness due to the corrosion effect. Variation in measured distances implied the existence of the surface anomalies. The results of the simulated surface anomalies showed that the percentage error was less than + 5%. The large value of average DC voltage gave indication of distance increment due to the depth of the surface anomalies. The developed ultrasonic instrumentation system is capable to monitor the internal corrosion of pipeline

Design and development of a CCD based optical tomography measuring system for particle sizing identification

This research investigates the use of charge coupled device (abbreviated as CCD) linear image sensors in an optical tomographic instrumentation system used for sizing particles. Four CCD linear image sensors are configured around an octagonal shaped flow pipe for a four projections system. The measurement system is explained and uses four CCD linear image sensors consisting of 2048 pixels with a pixel size of 14µm by 14µm. Hence, a high-resolution system is produced. The designed instrumentation system is calibrated using known test pieces. Spherical shaped and irregular shaped particles are tested on the designed system to complete analysis of the overall performance of the system

Image Reconstruction of a Charge Coupled Device Based Optical Tomographic Instrumentation System for Particle Sizing

This research investigates the use of charge coupled device (abbreviated as CCD) linear image sensors in an optical tomographic instrumentation system used for sizing particles. The measurement system, consisting of four CCD linear image sensors are configured around an octagonal shaped flow pipe for a four projections system is explained. The four linear image sensors provide 2,048 pixel imaging with a pixel size of 14 micron × 14 micron, hence constituting a high-resolution system. Image reconstruction for a four-projection optical tomography system is also discussed, where a simple optical model is used to relate attenuation due to variations in optical density, [R], within the measurement section. Expressed in matrix form this represents the forward problem in tomography [S] [R] = [M]. In practice, measurements [M] are used to estimate the optical density distribution by solving the inverse problem [R] = [S]−1[M]. Direct inversion of the sensitivity matrix, [S], is not possible and two approximations are considered and compared—the transpose and the pseudo inverse sensitivity matrices

MyDWP: A new digital wave processor for satellite onboard data processing

Scientific communities nowadays benefit a lot from studies of data gathered from space through satellites [Jilla and Miller, 1997]. For instance, the main goal of the Cluster II mission is to study the small-scale plasma structures in the key plasma regions: solar wind and bow shock, magnetopause, polar cusps, magneto-tail and auroral zone [Escoubet and Schmidt, 2000]. The information helps meteorologists to understand various weather phenomena that occur at many places around the world [Escoubet et al., 1997]. Monitoring the effect of the Sun on the Earth environment through the satellite data enables us to understand several events such as disruption of power line, interference in long distance radio communications and thunderstorms that cause great impacts on human life and economy

Image Reconstruction of a Charge Coupled Device Based Optical Tomographic Instrumentation System for Particle Sizing

This research investigates the use of charge coupled device (abbreviated as CCD) linear image sensors in an optical tomographic instrumentation system used for sizing particles. The measurement system, consisting of four CCD linear image sensors are configured around an octagonal shaped flow pipe for a four projections system is explained. The four linear image sensors provide 2,048 pixel imaging with a pixel size of 14 micron × 14 micron, hence constituting a high-resolution system. Image reconstruction for a four-projection optical tomography system is also discussed, where a simple optical model is used to relate attenuation due to variations in optical density, [R], within the measurement section. Expressed in matrix form this represents the forward problem in tomography [S] [R] = [M]. In practice, measurements [M] are used to estimate the optical density distribution by solving the inverse problem [R] = [S]−1[M]. Direct inversion of the sensitivity matrix, [S], is not possible and two approximations are considered and compared—the transpose and the pseudo inverse sensitivity matrices

Optical tomography system based on charges-coupled device linear image sensors

Industrial processes are often controlled using process measurements at one or more points. The amount of information contained in such measurements is often minimal, and in some cases (multiphase flow) there are no adequate sensors [1]. To understand better certain chemical processes, a more sophisticated approach is needed. Process tomography is a means of visualising the internal behaviour of industrial processes, where tomographic images provide valuable information about the process for assessment of equipment designs and on-line monitoring [2]