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& Considering the influence of the limited measurement data on the effectiveness of the image reconstruction algorithms in industrial multiphase flow tomography, an iterative filtering reconstruction algorithm is proposed by redefining inverse problem in this article. In order to improve the image quality in iterative reconstruction algorithm, Wiener filter and soft-threshold algorithm are employed as constraints for the reconstructed image. The developed algorithm is applied to gamma-CT based two-phase flow measurements, both simulated and experimental. The results demonstrate that the proposed method cannot only realize the flow regime identification on horizontal pipe, but also improve the iterative reconstruction process, i.e., the reconstructed image quality is enhanced and the iteration number is reduced.

This paper describes the application of a lowenergy γ-ray computed tomography (CT) system to twophase flow measurement. A 241 m A (59.5 KeV) γ-ray source is used to penetrate a 82 mm i.d. pipe, an array of 17 detector elements is utilized to measure the projection data, and a rotating mechanism is employed to get 3 to 11 projections with the single source. Because this system offers only 3 to 11 projections, and the detector elements are sparsely arranged, conventional reconstruction algorithms are ineffective, thus improvement based on matrix completion algorithm has been developed to improve the imaging quality. Reconstructed results from measurement data demonstrate the effectiveness of this technique. Dynamic experiment result of a horizontally moving Perspex model are also presented, which clearly show the shape and size of the model.

A new file detection system based on FPGA and TDLAS technology is proposed to solves the shortcomings of traditional fire detection sensors in airplane cabins, such as poor reaction time, high false alarm rate, and limited sensitivity. First, an FPGA-centered system architecture is constructed using gas molecule spectrum absorption theory. The FPGA is used to create a laser wavelength modulation signal generating module, as well as a high-speed data transmission module, a FIR digital low-pass filter module, and a digital phase-sensitive detector module. The system was used to evaluate the strength of gas absorption peaks at different concentrations. The second harmonic was extracted from the data while measuring and removing the interference from the external environment. The relative error of the final fitting results was less than 0.04%, which proves the feasibility of the design.

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