A Review of Process Tomography Application in Inspection System

Abstract

The inspection system is crucial to ensure the system is always in a good condition. A technique that can be used for inspection system is process tomography. By promising non-destructive approach; various types of process tomography applied in civil, manufacturing and electrical applications. The purpose of this paper is to review the types of process tomography such as ultrasonic tomography, x-ray tomography, optical tomography, electrical resistance tomography, and electrical impedance tomography that had been applied to the inspection system. Variety techniques of inspection based on those sensors briefly discussed in this paper. The result showed that the process tomography expanded tremendously in the inspection system. Finally, a potential future research on the inspection system in the civil application proposed in this paper.

Thermal imaging based pre-diagnostics tool for Graves’ disease

“…Several other modalities are under development to fill the remaining gaps and reduce usage's side effects. Electrical impedance tomography (EIT), Infrared thermography (IRT), and LASER-based imaging methods are just a few of them [6][7][8][9][10]. EIT provides 2D images with a poor spatial resolution of the order of millimeters [11] but offers a relatively faster temporal resolution.…”

Multi-frequency fusion ultrasonic tomography for gas–liquid two-phase distribution imaging

“…Regarding bubble distribution imaging, the majority of UT approaches are in transmission mode, using single-frequency time-difference (SFTD) amplitude data [17]. It estimates the change of attenuation coefficient from the signal amplitude difference between two measured states under the same frequency, through which reduced artifact and improved robustness are achieved to some extent [18]. However, with different gas bubble sizes, the excitation frequency of conventional SFTD UT is empirically selected among low frequencies [19], resulting in acoustic diffraction/scattering, low spatial resolution and large reconstruction error.…”

“…In this paper, we demonstrate the feasibility of multifrequency excitation in UT by proposing a novel strategy of multi-frequency fusion UT (MFFUT), which manages the comprehensive modeling of transmissive attenuation and selfadaptive fusion of multi-frequency reconstruction through processing the measurement data with a frequency-dependent forward model and a metric-weighted fusion algorithm. The contributions of this work compared with other UT studies are threefold: (1) multi-frequency UT has a potential of characterizing bubble size and distribution from spectrum information, which is fundamentally different from the existing single-frequency UT approaches [17,18]; (2) the frequencydependent forward model quantitatively describes the absorption attenuation of the medium and suppresses the sensing signal of the multi-scattering wave; and (3) instead of using frequency-difference measurement data like FDEIT, we present an image fusion method by calculating the synthetic weight operator and adaptively select fusing images to achieve a more accurate result. The proposed MFFUT approach is qualitatively and quantitatively evaluated with different types of reconstruction algorithms for different gas bubble distributions, through which higher reconstruction accuracy versus SFTD UT approaches is achieved.…”

Fixed-point Sensitivity Maps for Image Reconstruction in Tomography

“…Tomography systems that use computers to reconstruct the images are called Computed Tomography (CT). This is because the tomography systems developed are using computers to reconstruct the images [2][3][4][5][6][7] . The hardware designs developed are call Data Acquisition Systems (DAS) that can be connected to the computers for data processing of image reconstruction.…”