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Study on image reconstruction of capacitively coupled electrical impedance tomography (CCEIT)

MEASUREMENT SCIENCE AND TECHNOLOGY 2019年第9期30卷 094002-094002页

作者： Wang, Yuxin Ji, Haifeng Huang, Zhiyao Wang, Baoliang Li, Haiqing Zhejiang Univ State Key Lab Ind Control Tech Coll Control Sci & Engn Hangzhou 310027 Zhejiang Peoples R China

The aim of this work is to study the image reconstruction of capacitively coupled electrical impedance tomography (CCEIT) by using total impedance of a gas-liquid two-phase flow. The results of image reconstruction that utilise the real part, the imaginary part, the amplitude of the impedance, and the image reconstruction results by making use of different parts of the total impedance are investigated and discussed. By combining a linear back projection (LBP) algorithm and a K-means clustering algorithm, a new image reconstruction algorithm for CCEIT is proposed. The LBP is used to obtain the original reconstructed image. The K-means is adopted to automatically obtain the gray level threshold. The final reconstructed image is acquired with an established gray level threshold filter. With the new algorithm (LBP + K-means), the images reconstructed by using different parts of the impedance are obtained. To make full use of total impedance information, an image fusion method based on the weighted combination method is presented. With a developed 12-electrode CCEIT prototype, the image reconstruction experiments are conducted. Experimental results show that all three parts of the impedance can reflect the phase distribution characteristics of the gas-liquid two-phase flow from different aspects. image fusion results indicate that making full use of the different parts of the total impedance of the gas-liquid two-phase flow can effectively improve the quality of the image reconstruction. The experimental results also verify the feasibility and the effectiveness of the proposed new image reconstruction algorithm. Compared with conventional algorithms, the proposed image reconstruction method can obtain comparable/better image reconstruction results with less prior knowledge. The influence of manual intervention on the image reconstruction results can be effectively avoided.

关键词： gas-liquid two-phase flow electrical tomography impedance image reconstruction algorithm K-means image fusion

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A heterogeneous hardware scheme for accelerating the image reconstruction process of electrical tomography

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MEASUREMENT SCIENCE AND TECHNOLOGY 2023年第10期34卷 105902-105902页

作者： Cui, Ziqiang Sun, Can Yang, Pengyu Wang, Huaxiang Tianjin Univ Sch Elect & Informat Engn Tianjin 300072 Peoples R China

Currently, most of the electrical tomography measurement systems are developed on microcontroller units, digital signal processors, or field programmable gate arrays, whereas image reconstruction and display functions are implemented in a separate host computer. Therefore, the complete hardware usually comprises a measurement system and an image reconstruction computer. The current trend is to develop industrial standard electrical tomography systems, which can implement the image reconstruction and measurement functions into an integrated processor/chip. However, most of the above mentioned processors do not provide the necessary computational resources as required by the computationally intensive image reconstruction function. This paper describes a hardware scheme for implementing image reconstruction functions on a heterogeneous hardware platform, wherein the processor system and programmable logics (PLs) are tightly coupled and can achieve better resource utilization and overall system performance. By adopting a high-level synthesis method, the image reconstruction algorithms can be realized jointly by the PLs and processor system. In this hardware scheme, the algorithms are properly optimized to achieve better data throughput and execution efficiency, that is, by utilizing parallel computation in PLs. Details of the hardware scheme and method of accelerating the image reconstruction process are presented in this paper. Implementation results show that the proposed heterogeneous hardware scheme can achieve the image reconstruction rates of 24 and 1700 frames per second while employing the iterative and non-iterative algorithms, respectively.

关键词： electrical tomography high-level synthesis image reconstruction algorithm electrical capacitance tomography hardware accelerator heterogeneous platform

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Three-dimensional photoacoustic imaging by sparsearray detection and iterative image reconstruction

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JOURNAL OF BIOMEDICAL OPTICS 2008年第5期13卷 54052-54052页

作者： Ephrat, Pinhas Keenliside, Lynn Seabrook, Adam Prato, Frank S. Carson, Jeffrey J. L. Imaging Program Lawson Hlth Res Inst London ON N6A 4V2 Canada Univ Western Ontario Dept Med Biophys London ON N6A 5C1 Canada St Joseph Hlth Care Dept Med Imaging London ON N6A 4V2 Canada

Photoacoustic imaging (PAI) has the potential to acquire 3-D optical images at high speed. Attempts at 3-D photoacoustic imaging have used a dense 2-D array of ultrasound detectors or have densely scanned a single detector on a 2-D surface. The former approach is costly and complicated to realize, while the latter is inherently slow. We present a different approach based on a sparse 2-D array of detector elements and an iterative reconstruction algorithm. This approach has the potential for fast image acquisition, since no mechanical scanning is required, and for simple and compact construction due to the smaller number of detector elements. We obtained spatial sensitivity maps of the sparse array and used them to optimize the image reconstruction algorithm. We then validated the method on phantoms containing 3-D distributions of optically absorbing point sources. reconstruction of the point sources from the time-domain signals resulted in images with good contrast and accurate localization (<= 1 mm error). image acquisition time was 1 s. The results suggest that 3-D PAI with a sparse array of detector elements is a viable approach. Furthermore, the rapid acquisition speed indicates the possibility of high frame rate 3-D PAI. (C) 2008 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.2992131]

关键词： photoacoustic imaging (PAI) optical absorption three-dimensional imaging ultrasound array image reconstruction algorithm iterative back-projection

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ITERATIVE FILTERING reconstruction algorithm FOR GAMMA COMPUTERIZED TOMOGRAPHY: APPLICATION TO TWO-PHASE FLOW VISUALIZATION

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INSTRUMENTATION SCIENCE & TECHNOLOGY 2012年第1期40卷 1-16页

作者： Xue, Qian Wang, Huaxiang Hao, Kuihong Xin, Shan Tianjin Univ Sch Elect Engn & Automat Tianjin 300072 Peoples R China Civil Aviat Univ China Mech & Elect Engn Coll Tianjin Peoples R China

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.

关键词： computerized tomography (CT) image reconstruction algorithm two-phase flow

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Acoustic tomography system for online monitoring of temperature fields

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IET SCIENCE MEASUREMENT & TECHNOLOGY 2017年第5期11卷 623-630页

作者： Yan, Hua Ma, Zhao Zhou, Ying Gang Shenyang Univ Technol Sch Informat Sci & Engn Shenyang 110870 Liaoning Peoples R China

For online monitoring of complex temperature distributions, an acoustic tomography system based on sound travel-time measurement is developed. For coping with the reverberation phenomenon in actual measurement, an anti-reflection interference measurement method for sound travel-time is proposed based on cross-correlation and peak recognition. In view of the fact the pixel number provided by commonly used reconstruction algorithms, such as least-squares methods, is very limited, radial basis function approximation and regularisation technique are used, which leads to the pixel number of the reconstruction image increasing dramatically. Mixed programming with LabVIEW and MATLAB is used. Queue structure is adopted to make data acquiring program and data processing program parallel. Test results show that the system can run normally as designed. The measurement values of sound travel-time acquired by the proposed method are stable even in strong reflection interference. Test results show that the system can run normally as designed. The measurement values of sound travel-time acquired by the proposed method are stable even in strong reflection interference. The temperature fields reconstructed are coincided with actual fields, and correctly reflect the temperature changes in the measured area with the heater number, heater location and heating time.

关键词： temperature measurement acoustic tomography temperature distribution acoustic variables measurement time measurement reverberation acoustic wave interference acoustic correlation least squares approximations approximation theory image recognition image reconstruction virtual instrumentation mathematics computing data acquisition acoustic tomography system complex temperature distribution monitoring sound traveltime measurement reverberation phenomenon antireflection interference measurement method cross-correlation peak recognition image reconstruction algorithm least-square method radial basis function approximation regularisation technique LabVIEW programming data processing program data acquiring program queue structure MATLAB programming

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Efficient Phase Shift Migration for MIMO 2-D Imaging in Millimeter-Wave Band

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IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS 2021年第2期31卷 215-218页

作者： Yang, Guan Li, Chao Gao, Hang Li, Hongwei Zheng, Shen Fang, Guangyou Chinese Acad Sci Aerosp Informat Res Inst Beijing 100190 Peoples R China Chinese Acad Sci Key Lab Electromagnet Radiat & Sensing Technol Beijing 100190 Peoples R China Univ Chinese Acad Sci Sch Elect Elect & Commun Engn Beijing 100049 Peoples R China

The real-time capability becomes more and more important for the millimeter-wave imaging systems in variety of applications. To achieve this purpose, the imaging scheme with multiple-input-multiple-output (MIMO) is one of the potential ways, while still limited by the high computational complexity of the conventional MIMO image reconstruction algorithm, which is commonly based on the back-projection theorem. In this letter, an efficient phase shift migration (PSM) image reconstruction algorithm was proposed to improve the computation efficiency for MIMO systems 2-D imaging. By decomposing and approximating the PSM operator reasonably, only complex multiplication and Fourier transform (FT) operations are employed which can be easily carried out to reduce computation cost. An MIMO side-looking prototype system was designed for proof experiments in the 100-GHz band. Although the proposed algorithm introduces a negligible phase error, the experimental results show that the error can be ignored and the algorithm can achieve high-precision real-time imaging.

关键词： Imaging MIMO communication image reconstruction Approximation algorithms Real-time systems Radar imaging Microwave imaging image reconstruction algorithm millimeter-wave (MMW) multiple-input– multiple-output (MIMO) radar phase shift migration (PSM)

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Implementation of Step-Frequency Continuous-Wave Scheme in Millimeter-Wave Inline Holography for Interferences Elimination

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IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 2013年 12卷 1176-1179页

作者： Gao, Xiang Li, Chao Sun, Zhaoyang Fang, Guangyou Chinese Acad Sci Key Lab Electromagnet Radiat & Sensing Technol Inst Elect Beijing 100190 Peoples R China

A millimeter-wave (MMW) inline holographic imaging method based on step-frequency continuous-wave (SFCW) scheme is presented in this letter. By analyzing and decomposing the received SFCW power in range domain, it is found that the background and twin-image interferences can be well separated from the image-related term, and therefore can be removed with appropriate range windows. Moreover, a corresponding mathematical algorithm is developed to reconstruct the image from the inline hologram. To validate the effectiveness of the presented approach, a 200-GHz prototype system is designed and fabricated. Experimental results demonstrate the good performance of the imaging system and its potential application in high-resolution target detection.

关键词： image reconstruction algorithm interferences elimination millimeter-wave (MMW) inline holography range domain decomposition step-frequency continuous-wave (SFCW)

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Improvement of signal-to-noise ratio and image stability in magnetic inductance tomography by exploiting transient response analysis

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IET image PROCESSING 2011年第5期5卷 508-512页

作者： Yin, W. Peyton, A. J. Shanghai Maritime Univ Sch Logist Engn Shanghai 200135 Peoples R China Univ Manchester Sch Elect & Elect Engn Manchester Lancs England

This study presents a method to increase the signal-to-noise ratio (SNR) and image stability in magnetic inductance tomography (MIT) data acquisition by exploiting transient response analysis. In front-end circuits for inductance measurements in MIT, a critical step is the phase sensitive demodulation, which includes a low pass filter. When the excitation source is switched from one coil to the next, a transient response occurs as the received voltage level changes. Normally, data acquisition takes place after the transient response finishes and the voltage level becomes nearly constant. In this study, a method is proposed to increase the SNR by exploiting the information embedded in the transient response. Simulation and experimental tests have confirmed the validity of the method;standard deviations of the measured inductance decrease more than 50%. The impact of improvement in SNR in raw inductance measurement on image stability is considered with different image reconstruction algorithms. The error propagation in the image reconstruction process is discussed.

关键词： low pass filter Measurement and error theory inductance measurements measurement errors image reconstruction magnetic inductance tomography image stability detector circuits inductive sensors Optical, image and video signal processing error propagation Impedance and admittance measurement electromagnetic induction image reconstruction algorithm signal-to-noise ratio low-pass filters image processing and restoration transient response analysis tomography inductance measurement phase sensitive demodulation Electrical instruments and techniques Measurement theory Sensing devices and transducers Sensing and detecting devices MIT data acquisition

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Application of ultrasonic tomography to monitoring gas/liquid flow

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CHEMICAL ENGINEERING SCIENCE 1997年第13期52卷 2171-2183页

作者： Xu, LJ Han, YT Xu, LA Yang, JS TIANJIN UNIV DEPT APPL PHYSTIANJIN 300072PEOPLES R CHINA

On the basis that a gas/liquid two-phase flow was considered as a strongly inhomogeneous medium due to the high contrast in acoustic impedance distribution, the authors analysed the inherent dependency of the incomplete tomographic projections on the distribution of bubbles in liquid when using transmission-mode (TM) ultrasound computerized tomography (UCT). A mathematical model describing the acoustic characteristics of this flow was established. A transmission-mode ultrasonic system for tomographic imaging of gas/liquid flow was designed based upon a fast binary back-projection image reconstruction algorithm. Emphasis was made on the evaluation of its performance and its application to flow regime identification. Several flow pattern models were made and the corresponding monitoring results were given. Finally, limitations and possible future implementations of the system are discussed. (C) 1997 Elsevier Science Ltd. All rights reserved.

关键词： gas/liquid two-phase fluid ultrasound transmission-mode (TM) tomography image reconstruction algorithm

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An endoscopic diffuse optical tomographic method based on the effective detection range

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JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2013年第4期21卷 527-543页

作者： Qin, Zhuanping Cui, Shanshan Zhao, Huijuan Zhou, Xiaoqing Jia, Mengyu Yang, Yanshuang Fan, Ying Gao, Feng Tianjin Univ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China Tianjin Key Lab Biomed Detecting Tech & Instrumen Tianjin Peoples R China

Endoscopic diffuse optical tomography (DOT) is a new medical imaging modality with the potential applications in functional imaging of the internal organs. To cut down the measurement time and the computation burden of image reconstruction, in this paper, we developed the image reconstruction algorithm with the partial measurement in the effective detection range (EDR) of a tubular tissue and the corresponding endoscopic imaging system with a novel endoscopic probe for flexibly selecting the detection sites. For a typical inner size and optical properties of the cervix, it is found that EDR is less than half of the inner circumference. Comparing to the traditional method, the adoption of EDR results in a reduction of more than a factor of two in the time cost for a measurement cycle and for the total iteration reconstruction. images reconstructed from the simulation data demonstrate that the proposed method achieves equivalent image quality to that obtained from the complete data set. The images reconstructed from the EDR measurements on cervix-like solid phantoms show that both the location and size of the targets are reconstructed correctly. The proposed method will be useful to the development of endoscopic DOT technologies for cancer detection in tubular organs including cervix.

关键词： Endoscopic diffuse optical tomography partial measurement effective detection range frequency-domain image reconstruction algorithm

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